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27 October 2020 Palynology of the Mount Johnstone Formation (Mississippian), Southern New England Orogen, New South Wales, Australia
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Abstract

This renewed palynological study of the Mount Johnstone Formation, at Balickera in the Hunter Valley region of New South Wales (eastern Australia), discloses a considerably more diverse palynoflora – termed the Grandispora maculosa Assemblage – than was reported in 1968. Represented are some 51 species of palynomorphs, comprising 46 species of trilete spores (distributed among 27 genera), three species of monolete spores (three genera), one species of hilate spores, and a single algal-cyst species. The following species are newly instituted: Verrucosisporites adgeratus, V. johnstonense, V. pavimentatus, Anapiculatisporites robertsii, Convolutispora perplicata, Knoxisporites balickeraensis, Densoisporites argutus, Laevigatosporites demutabilis, and Latosporites durabilis. Quantitatively important and/or consistently represented species include Reticulatisporites magnidictyus (particularly), Punctatisporites spp., Verrucosisporites spp., Rattiganispora apiculata, Grandispora maculosa, Indotriradites kuttungensis, Velamisporites australiensis, Laevigatosporites demutabilis, and Psomospora detecta. The absence of marine palynomorphs supports the previously envisaged, predominantly fluvial deposition of the Mount Johnstone Formation. Key palynostratigraphic indices, in conjunction with absolute-age determinations obtained from sub- and suprajacent rocks, indicate that the G. maculosa palynoflora and its hosting Mount Johnstone strata are Mississippian – specifically middle–late Visean – in age. This dating also applies to similarly palyniferous deposits in the northern Perth and Carnarvon basins of Western Australia. Beyond Eastern Gondwana, equivalents of the G. maculosa association have been reported from Western Gondwana (Brazil and Argentina in particular) and, to a lesser extent, from Northern Gondwana, thus attesting to its wide distribution and chronostratigraphic significance within the supercontinent and its distinctiveness vis-à-vis Euramerican regions.

1. Introduction

Palynological studies of largely nonmarine Mississippian successions in Gondwana have increased considerably in recent years, with emphasis on the stratigraphic and palaeogeographic significance of the palynofloras, underpinned by detailed taxonomic analyses. This applies mainly to Western Gondwana (principally Brazil and Argentina: Melo and Loboziak 2003; Playford and Melo 2012; Melo and Playford 2012; Césari et al. 2011; di Pasquo and Iannuzzi 2014; and references cited therein) and Eastern Gondwana (Australia: Jones and Truswell 1992; Playford 2015, 2017; Playford and Mory 2017).

Many of the species constituting the Grandispora maculosa miospore association – as described initially by Playford and Helby (1968) from the Italia Road Formation (now Mount Johnstone Formation) of the Hunter Valley region of New South Wales – have subsequently been identified in Middle to Upper Mississippian deposits elsewhere in Gondwana, thus enhancing chronostratigraphic correlations and palaeogeographic inferences over much of the supercontinent and, more particularly, between Eastern and Western Gondwana.

The Playford and Helby paper can be viewed essentially as an interim or reconnaissance study. Subsequent detailed palynological investigations of coeval or near-coeval strata elsewhere in Gondwana have provided the impetus and raison dtre for the current, more comprehensive examination of the Mount Johnstone Formation's palynoflora, thereby enhancing and strengthening its Gondwanan stratigraphic and other potentialities.

2. Geological setting, stratigraphy, and sampled section

The rural settlement of Balickera, New South Wales (Figure 1), whence the study samples derive, is located in the Lower Hunter Valley region, which lies within the southern part of the Devonian–Triassic New England Orogen (NEO; see, inter alia, Roberts et al. 2006; Rosenbaum 2012, fig. 1b). The orogen includes a Devonian–Carboniferous forearc basin: a curving, auriform, oroclinal structure (Shaanan et al. 2014, fig. 1c). The southernmost part of the NEO within the orocline comprises three blocks that are segregated by meridionally striking, syn-depositional faults (Roberts and Engel 1987). From west to east these are the Rouchel, Gresford, and Myall blocks, the Gresford being bounded by the Karakurra and Williams River faults to the west and east, respectively (Phillips et al. 2016, fig. 1).

Figure 1.

Locality map, New South Wales, with inset of Balickera area. Adapted from Playford and Helby (1968, fig. 1).

img-z2-1_621.jpg

The Mount Johnstone Formation is exposed principally in the Rouchel and Gresford blocks (Geeve et al. 2002, fig. 2), and its 650-m-thick type section is located within the latter (Hamilton et al. 1974, p. 83; Roberts et al. 1991, p. 94). The Italia Road Formation and the conformably underlying Balickera Conglomerate – q.v. Rattigan (1967a, 1967b, 1967c) and adopted by Playford and Helby (1968) – are developed in the westernmost Myall Block immediately to the east of the aforementioned Williams River Fault (Rattigan 1967a, fig. 1). On lithostratigraphic grounds, these two formations were jointly subsumed nomenclaturally into the Mount Johnstone Formation (Roberts et al. 1991, p. 94–95), with the former Balickera Conglomerate termed informally the lower member of the Mount Johnstone Formation. Moreover, Rattigan's (1967a) Grahamstown Lake Formation, succeeding his Italia Road Formation, apparently conformably, was regarded by Roberts et al. (1991, p. 94) as being synonymous with the previously established Seaham Formation. These nomenclatural changes are followed here.

The Balickera section of the Mount Johnstone Formation (Rattigan 1967a, figs 1, 4; Figures 1, 2 herein) is more complete and informative than the type section. It was exposed as a continuous succession – transverse to the strike and dipping relatively steeply (30–55°) – during the 1958–early 1960s excavation of a canal, 8 km long, connecting the Williams River near Seaham to the Grahamstown Lake (aka Grahamstown Dam: a potable water reservoir serving the Lower Hunter region). Here, the Mount Johnstone Formation comprises 417 m of polymictic boulder conglomerates with interbeds of massive grey tuffs and ignimbrites (corresponding to Rattigan's Balickera Conglomerate), succeeded conformably by a rhythmic/cyclical unit (Rattigan's Italia Road Formation) comprising 360 m of mostly fine- to coarse-grained lithic sandstones and interbedded, variably carbonaceous shales and siltstones, and poor coal, together with minor tuffs, bentonites, and cherts. Note that Rattigan's (1967a, 1967b) usage of the term ‘cyclothem’ is at variance with accepted terminology: e.g. ‘cyclothems result from repeated alternations of deposition in marine and nonmarine environments’, as exemplified by the Pennsylvanian of the Illinois Basin (Wicander and Monroe 2014, p. 225). According to Roberts et al. (1991, p. 98), the Mount Johnstone Formation accumulated in a wholly nonmarine fluvial environment, the conglomeratic lower part signifying a fan deposit from an uplifted source area, and the succeeding sandy, silty, carbonaceous sediments representing cyclically repetitive beds regarded as ‘lateral accretionary units (deposited) by streams'. Earlier, Rattigan (1967b, p. 127) had envisaged that the cycles resulted from episodic flash-flooding generated by melted glaciers. Moreover, there is clear evidence of glacigene deposition in the overlying Seaham Formation (e.g. Süssmilch and David 1920; Roberts and Engel 1987; Fielding et al. 2008).

Figure 2.

Stratigraphic section of the formerly named Italia Road Formation – now included with the underlying Balickera Conglomerate in the Mount Johnstone Formation – as exposed and measured (i.e. before flooding) in the Balickera canal excavation, whence the samples studied herein, as originally by Playford and Helby (1968), were collected. Based on Rattigan (1967a, fig. 4), but see text (section 2) regarding inapt usage of ‘cyclothem'.

img-z3-1_621.jpg

The samples studied herein, collected from levels indicated in Figure 2, are those investigated initially by Playford and Helby (1968). They represent the finer and palyniferous lithologies in the now-flooded Balickera excavation: mostly pale grey to black, carbonaceous siltstones, poor coal, and fine-grained sandstones.

3. Laboratory preparation, microscopy, and repository

Conventional palynological laboratory procedures were applied in the extraction and concentration of the palynomorphs from the samples (q.v. Playford and Helby, 1968, p. 105–106). The samples proved abundantly palyniferous, yielding spores in a very good to excellent state of preservation, as evidenced by Plates 1–11 herein.

The palynomorphs figured in the plates were captured as high-resolution (TIFF) images with an Olympus BH2 binocular microscope, using either a 40× or a 60× oil-immersion objective, with attached Olympus DP26 digital camera. The images were acquired via Olympus cellSensVR software, and the plates were assembled by means of CorelDRAWVR graphics suite.

All 168 palynomorphs figured herein are preserved in slides housed permanently in the Palaeontological Type Collection maintained by the Geological Survey of New South Wales, W.B. Clarke Geoscience Centre, 947–953 Londonderry Road, Londonderry, NSW 2753, Australia. Curatorial details are provided in Appendix 1.

4. Systematic palaeontology

Riding et al. (2018) have provided a useful and opportune commentary on the taxonomic-citation consequences of online vs. print publication (the latter, of course, normally post-dating the former). Providing that the online version is identical with the printed version (aside from differences in pagination), its date of issuance is accepted as the date of effective publication. This complies with the International Code of Nomenclature for algae, fungi, and plants (ICN; Turland et al. 2018, article 29) and had been followed earlier by Playford and Mory (2017, p. 280). Reference listings should, as they do herein, cite both modes of publication (where such exist).

4.1. Taxonomic inventory

The species identified in this study are listed below and arranged in accordance with the systematic order adopted in the ensuing descriptive section. Square-bracketed plate/figure citations refer to photomicrographs in the present paper. Asterisks denote species described by Playford and Helby (1968).

Calamospora spp. [Plate 1, figures 3, 4]

Leiotriletes ornatus Ishchenko, 1956 [Plate 1, figure 1]

Phyllothecotriletes golatensis Staplin, 1960 [Plate 1, figure 2]

*Punctatisporites lucidulus Playford & Helby, 1968 [Plate 1, figures 9, 10]

*Punctatisporites subtritus Playford & Helby, 1968 [Plate 1, figures 11–14]

Retusotriletes separatus Playford, 2015 [Plate 1, figure 5]

Cyclogranisporites firmus Jones & Truswell, 1992 [Plate 1, figures 6–8]

Verrucosisporites adgeratus sp. nov. [Plate 2, figures 1a, b–5a, b]

*Verrucosisporites aspratilis Playford & Helby, 1968 [Plate 2, figures 6–8]

Verrucosisporites basiliscutis Jones & Truswell, 1992 [Plate 2, figure 9a, b]

Verrucosisporites gregatus Playford & Melo, 2012 [Plate 2, figures 10, 11]

Verrucosisporites iannuzzii di Pasquo in di Pasquo & Iannuzzi, 2014 [Plate 2, figures 12–15; Plate 3, figures 1a, b–3]

*Verrucosisporites italiaensis Playford & Helby, 1968 [Plate 4, figures 13–15]

Verrucosisporites johnstonense sp. nov. [Plate 3, figures 12–15]

Verrucosisporites pavimentatus sp. nov. [Plate 3, figures 8–11]

*Verrucosisporites quasigobbettii Jones & Truswell, 1992 [Plate 4, figures 1a, b–12a, b]

Verrucosisporites souzai di Pasquo in di Pasquo & Iannuzzi, 2014 [Plate 3, figures 4–7]

Anapiculatisporites amplus Playford & Powis, 1979 [Plate 5, figures 14–16]

Anapiculatisporites concinnus Playford, 1962 [Plate 5, figures 10–13]

Anapiculatisporites hispidus Butterworth & Williams, 1958 [Plate 5, figures 8, 9]

Anapiculatisporites robertsii sp. nov. [Plate 5, figures 1a, b–5]

Dibolisporites disfacies Jones & Truswell, 1992 [Plate 5, figures 6, 7]

*Raistrickia accincta Playford & Helby, 1968 [Plate 7, figures 1–4]

*Raistrickia corymbiata Playford in Playford & Mory, 2017 [Plate 7, figures 5, 6]

*Raistrickia radiosa Playford & Helby, 1968 [Plate 7, figures 7, 8]

Brochotriletes diversifoveatus Playford & Satterthwait, 1985 [Plate 6, figure 9a, b]

Convolutispora perplicata sp. nov. [Plate 7, figures 16–18]

*Cordylosporites asperidictyus (Playford & Helby, 1968) Dino & Playford, 2002 [Plate 6, figures 15–17]

*Foveosporites pellucidus Playford & Helby, 1968 [Plate 6, figures 10–14a, b]

Microreticulatisporites sp. A [Plate 7, figures 13–15]

*Rattiganispora apiculata Playford & Helby, 1968 emend. Playford, 1986 [Plate 7, figures 9a, b–12]

*Reticulatisporites magnidictyus Playford & Helby, 1968 emend. Playford, 2017 [Plate 6, figures 1–8]

Diatomozonotriletes sp. A [Plate 9, figure 1]

Knoxisporites balickeraensis sp. nov. [Plate 8, figures 3a, b–8]

Knoxisporites sp. A [Plate 8, figure 1a, b]

Knoxisporites sp. B [Plate 8, figure 2a, b]

Densoisporites argutus sp. nov. [Plate 9, figures 5, 6]

Densosporites infacetus Daemon, 1974 [Plate 9, figures 7, 8]

Densosporites sp. A [Plate 9, figures 9a, b, 10]

*Indotriradites kuttungensis (Playford & Helby, 1968) Playford, 1991 [Plate 9, figures 2–4]

Radiizonates arcuatus Loboziak, Playford & Melo, 2000 [Plate 9, figure 12a, b]

Vallatisporites sp. cf. V. hystricosus (Winslow, 1962) Wicander & Playford, 2013 [Plate 9, figure 13]

Diaphanospora sp. A [Plate 9, figure 11]

*Grandispora maculosa Playford & Helby, 1968 [Plate 9, figures 14, 15]

*Velamisporites australiensis (Playford & Helby, 1968) di Pasquo, Azcuy & Souza, 2003 [Plate 9, figures 16–18]

Velamisporites cortaderensis (Césari & Limarino, 1987) Playford, 2015 [Plate 10, figures 1–4]

Aratrisporites saharaensis Loboziak, Clayton & Owens, 1986 [Plate 11, figures 12, 13]

Laevigatosporites demutabilis sp. nov. [Plate 10, figures 5–12]

Latosporites durabilis sp. nov. [Plate 10, figures 13–18]

*Psomospora detecta Playford & Helby, 1968 [Plate 11, figures 1a, b–11]

Tetraporina horologia (Staplin, 1960) Playford, 1963 [Plate 11, figure 14]

Plate 1.

1, Leiotriletes ornatus Ishchenko, 1958, median focus. 2, Phyllothecotriletes golatensis Staplin, 1960, proximal focus. 3, 4, Calamospora spp., medial foci. 5, Retusotriletes separatus Playford, 2015, medial focus. 6–8, Cyclogranisporites firmus Jones & Truswell, 1992; 6, proximal focus; 7, medial focus; 8, equatorial aspect. 9, 10, Punctatisporites lucidulus Playford & Helby, 1968; 9, tetrad; 10, medial focus. 11–14, Punctatisporites subtritus Playford & Helby, 1968; 11, proximal focus; 12, equatorial aspect; 13, proximo-equatorial aspect; 14, proximal focus. Scale bars = 20 µm. For slide locations and other curatorial details see Appendix 1.

img-z5-1_621.jpg

Plate 2.

1a, b–5a, b, Verrucosisporites adgeratus sp. nov.; 1a, b, holotype, proximal and distal foci; 2a, b, proximal and distal foci; 3, medial focus; 4, near-distal focus; 5a, b, proximal and distal foci. 6–8, Verrucosisporites aspratilis Playford & Helby, 1968; 6, proximal focus; 7, distal focus; 8, equatorial aspect. 9a, b, Verrucosisporites basiliscutus Jones & Truswell, 1992, proximal and distal foci. 10, 11, Verrucosisporites gregatus Playford & Melo, 2012; 10, equatorial aspect; 11, proximal focus. 12–15, Verrucosisporites iannuzzii di Pasquo in di Pasquo & Iannuzzi, 2014; 12, equatorial aspect; 13a, b, proximal-equatorial and distal-equatorial foci; 14, proximal focus; 15, distal focus. Scale bars = 20 µm. For slide locations and other curatorial details see Appendix 1.

img-z6-1_621.jpg

Plate 3.

1a, b–3. Verrucosisporites iannuzzii di Pasquo in di Pasquo & Iannuzzi, 2014; 1a, b, proximal and distal foci; 2, equatorial aspect; 3, equatorial aspect. 4–7, Verrucosisporites souzai di Pasquo in di Pasquo & Iannuzzi, 2014; 4, proximal focus; 5, medial focus; 6, proximal focus; 7, proximal focus. 8–11, Verrucosisporites pavimentatus sp. nov.; 8, holotype, medial focus; 9, proximal focus; 10, proximal focus; 11, distal focus. 12–15, Verrucosisporites johnstonense sp. nov.; 12, holotype, medial focus; 13, distal focus; 14, medial focus; 15, proximal focus. Scale bars = 20 µm. For slide locations and other curatorial details see Appendix 1.

img-z7-1_621.jpg

4.2. Descriptive systematics

The ‘Turma’ form-classificatory scheme for fossil spores and pollen grains (collectively, miospores) was initiated by Potonié and Kremp (1954). This scheme, including modifications by later authors, is followed in the systematics section below. The form genera and species of palynomorphs are subject to provisions of the ICN (Turland et al. 2018).

Plate 4.

1a, b–12a, b, Verrucosisporites quasigobbettii Jones & Truswell, 1992; 1a, b, proximal and distal foci; 2, medial focus; 3, medial focus; 4, proximal focus; 5, proximal focus; 6, distal focus; 7, proximal-equatorial focus; 8a, b, proximal and distal foci; 9a, b, medial and distal foci; 10, distal focus; 11, medial focus; 12a, b, proximal and distal foci. 13–15, Verrucosisporites italiaensis Playford & Helby, 1968; 13, proximal focus; 14, distal focus; 15, medial focus. Scale bars = 20 µm. For slide locations and other curatorial details see Appendix 1.

img-z8-1_621.jpg

Plate 5.

1a, b–5, Anapiculatisporites robertsii sp. nov.; 1a, b, proximal and distal foci; 2a, b, distal and medial foci; 3a, b, holotype, proximal and distal foci; 4, proximal focus; 5, near-proximal focus. 6, 7, Dibolisporites disfacies Jones & Truswell, 1992; 6, medial focus; 7, distal focus of deformed specimen. 8, 9, Anapiculatisporites hispidus Butterworth & Williams, 1958; equatorial aspects. 10–13, Anapiculatisporites concinnus Playford, 1962; 10, medial focus; 11, distal focus; 12, equatorial aspect; 13, proximal focus. 14–16, Anapiculatisporites amplus Playford & Powis, 1979; 14, 15, equatorial aspects; 16, medial focus. Scale bars = 20 µm. For slide locations and other curatorial details see Appendix 1.

img-z9-1_621.jpg

Plate 6.

1–8, Reticulatisporites magnidictyus Playford & Helby, 1968 emend. Playford, 2017; 1, proximal focus; 2, distal focus; 3, proximal-equatorial aspect; 4, medial focus; 5, proximal focus; 6, proximal focus; 7, equatorial aspect; 8, equatorial aspect. 9a, b, Brochotriletes diversifoveatus Playford & Satterthwait, 1985, proximal and distal foci. 10–14a, b, Foveosporites pellucidus Playford & Helby, 1968; 10, proximal focus; 11, equatorial aspect; 12, medial focus; 13, equatorial aspect; 14a, b, proximal and distal foci. 15–17, Cordylosporites asperidictyus (Playford & Helby, 1968) Dino & Playford, 2002; 15, near-proximal focus; 16, medial focus; 17, distal focus. Scale bars = 20 µm. For slide locations and other curatorial details see Appendix 1.

img-z10-1_621.jpg

Plate 7.

1–4, Raistrickia accincta Playford & Helby, 1968; 1, medial focus; 2, medial focus; 3, proximal focus; 4, distal focus. 5, 6, Raistrickia corymbiata Playford in Playford & Mory, 2017, proximal and distal foci. 7, 8, Raistrickia radiosa Playford & Helby, 1968, distal and proximal foci. 9a, b–12, Rattiganispora apiculata Playford & Helby, 1968 emend. Playford, 1986; 9a, b, proximal and distal foci; 10, medial focus; 11, proximal focus; 12, medial focus. 13–15, Microreticulatisporites sp. A; 13, medial focus; 14, distal focus; 15, proximal-equatorial aspect. 16–18, Convolutispora perplicata sp. nov.; 16, two conjoined specimens, distal aspect; 17, holotype, proximal focus; 18, distal focus. Scale bars = 20 µm. For slide locations and other curatorial details see Appendix 1.

img-z11-1_621.jpg

Plate 8.

1a, b, Knoxisporites sp. A, proximal and distal foci. 2a, b, Knoxisporites sp. B, proximal and distal foci. 3a, b–8, Knoxisporites balickeraensis sp. nov.; 3a, b, holotype, proximal and distal foci; 4a, b, proximal and distal foci; 5–8, medial foci. Scale bars = 20 µm. For slide locations and other curatorial details see Appendix 1.

img-z12-1_621.jpg

The basionym is cited for all previously instituted species, followed where appropriate either by synonyms and generic re-combinations or by direct reference (cum syn.) to synonymy listings in prior publications. Whereas most of the species identified are described in detail, some species that have been satisfactorily circumscribed in published accounts are documented without comprehensive descriptions. In many such cases, supplementary morphological information is included, based on specimens observed during the present study.

Descriptive terminology follows definitions furnished by such authors as Kremp (1965), Smith and Butterworth (1967), Playford and Dettmann (1996), Punt et al. (2007), and Traverse (2007). Exinal sculptural elements termed ‘minute’ are appreciably less than 1 µm in height, thus making their precise form difficult to determine precisely. Equatorial diameters are specified by lowest and highest values, in most cases with intervening bracketed arithmetic mean – e.g. 45 (59) 72 µm. Type-species designations are abbreviated as follows: OD, original designation; SD, subsequent designation; and M, monotypy. Appendix 1 provides curatorial details pertaining to each species identified herein.

4.2.1. Miospores

Anteturma PROXIMEGERMINANTES R. Potonié, 1970
Turma TRILETES Reinsch, 1881 emend. Dettmann, 1963
Suprasubturma ACAVATITRILETES Dettmann, 1963
Subturma AZONOTRILETES Luber, 1935 emend. Dettmann, 1963
Infraturma LAEVIGATI Bennie & Kidston, 1886 emend. R. Potonié, 1956
Genus Calamospora Schopf, Wilson & Bentall, 1944

  • Type species. Calamospora hartungiana Schopf in Schopf, Wilson & Bentall, 1944 [OD].

  • Calamospora spp.
    Plate 1, figures 3, 4

  • Remarks. Representatives of this genus are only minor elements in the palynoflora and are of negligible stratigraphic import.

  • Genus Leiotriletes Naumova, 1939 ex Ishchenko, 1952
    emend. R. Potonié & Kremp, 1954

  • Type species. Leiotriletes sphaerotriangulus (Loose, 1932) R. Potonié & Kremp, 1955 [SD; Potonié & Kremp 1954, p. 120].

  • Plate 9.

    1, Diatomozonotriletes sp. A, medial focus. 2–4, Indotriradites kuttungensis (Playford & Helby, 1968) Playford, 1991; 2, distal focus; 3, 4, medial foci. 5, 6, Densoisporites argutus sp. nov.; 5, medial focus; 6, holotype, medial focus. 7, 8, Densosporites infacetus Daemon, 1974, medial foci. 10a, b, 11, Densosporites sp. A; 9a, b, proximal and distal foci; 10, medial focus. 11, Diaphanospora sp. A, medial focus. 12a, b, Radiizonates arcuatus Loboziak, Playford & Melo, 2000, proximal and distal foci. 13, Vallatisporites sp. cf. V. hystricosus (Winslow, 1962) Wicander & Playford, 2013, distal focus. 14, 15, Grandispora maculosa Playford & Helby, 1968, distal and proximal foci. 16–18, Velamisporites australiensis (Playford & Helby, 1968) di Pasquo, Azcuy & Souza, 2003; 16, proximal focus; 17, medial focus; 18, proximal focus. Scale bars = 20 µm. For slide locations and other curatorial details see Appendix 1.

    img-z13-1_621.jpg

    Plate 10.

    1–4, Velamisporites cortaderensis (Césari & Limarino, 1987) Playford, 2015; 1, medial focus; 2, distal focus; 3, 4, medial foci. 5–12, Laevigatosporites demutabilis sp. nov.; 5, holotype, medial focus; 6, medial focus; 7, equatorial aspect; 8, proximal focus; 9, medial focus; 10, equatorial aspect; 11, proximal focus; 12, equatorial aspect. 13–18, Latosporites durabilis sp. nov.; 13, holotype, proximo-equatorial aspect; 14, medial focus; 15, 16, proximal foci; 17, medial focus; 18, proximal focus. Scale bars = 20 µm. For slide locations and other curatorial details see Appendix 1.

    img-z14-1_621.jpg

    Plate 11.

    1a, b–11, Psomospora detecta Playford & Helby, 1968; 1a, b, proximal and distal foci; 2, medial focus; 3, proximal focus; 4, medial focus; 5–7, proximal foci; 8, equatorial aspect; 9, medial focus; 10, 11, proximal foci. 12, 13, Aratrisporites saharaensis Loboziak, Clayton & Owens, 1986, medial foci. 14, Tetraporina horologia (Staplin, 1960) Playford, 1963. Scale bars = 20 µm. For slide locations and other curatorial details see Appendix 1.

    img-z15-1_621.jpg

    Leiotriletes ornatus Ishchenko, 1956
    Plate 1, figure 1

  • Synonymy.

  • 1956 Leiotriletes ornatus Ishchenko, p. 22, pl. 2, figs 18–21. For other synonymy see Playford and Melo (2012, p. 13).

  • Remarks. The few specimens encountered herein accord with those described by previous authors, most recently by Playford (2015, p. 6).

  • Previous records. Essentially cosmopolitan in rocks of late Palaeozoic, commonly Mississippian, age.

  • Genus Phyllothecotriletes Luber, 1955 ex R.
    Potonié, 1958

  • Type species. Phyllothecotriletes nigritellus (Luber in Luber & Waltz, 1941) Luber, 1955 [SD; Potonié 1958, p. 17].

  • Phyllothecotriletes golatensis Staplin, 1960
    Plate 1, figure 2

  • Synonymy.

  • 1960 Phyllothecotriletes golatensis Staplin, p. 9, pl. 1, fig. 27. 2015 Phyllothecotriletes sp. A Playford, p. 6, fig. 2N.

  • Remarks. Very rare in the present palynoflora; the specimens observed closely resemble those described previously (e.g. Playford and Mory 2017, p. 281, pl. 1, figs 7, 8).

  • Previous records. From the Upper Mississippian of Alberta, Canada (Staplin 1960); and recorded by Playford (2015) and Playford and Mory (2017) from Western Australian strata of the northern Perth Basin and contiguous Carnarvon Basin in strata containing the Grandispora maculosa Assemblage.

  • Genus Punctatisporites Ibrahim, 1933 emend. R. Potonié & Kremp, 1954

  • Type species. Punctatisporites punctatus (Ibrahim, 1932) Ibrahim, 1933 [OD].

  • Punctatisporites lucidulus Playford & Helby, 1968
    Plate 1, figures 9, 10

  • Synonymy.

  • 1968 Punctatisporites lucidulus Playford & Helby, p. 107, pl. 9, figs 1, 2.

  • Remarks. This species is relatively abundant, including as tetrads, in the Mount Johnstone Formation samples. Present specimens accord with those described originally (Playford and Helby 1968) and subsequently (Playford 2015, p. 6, fig. 2L, M).

  • Dimensions (37 specimens). Equatorial diameter 39 (52) 63µm.

  • Previous records. Reported widely from middle Visean–Upper Mississippian successions of Eastern and Western Gondwana (Playford and Melo 2012, p. 14; Playford 2015; Playford and Mory 2017). Jones and Truswell (1992) indicated a range extension into the Pennsylvanian–?Lower Permian of Queensland's Galilee Basin, but they neither described nor illustrated any specimens they considered referable to the species.

  • Punctatisporites subtritus Playford & Helby, 1968
    Plate 1, figures 11–14

  • Synonymy.

  • 1968 Punctatisporites subtritus Playford & Helby, p. 107, pl. 9, figs 11, 12.

  • 1992 Punctatisporites gretensis auct. non Balme & Hennelly, 1956; Jones & Truswell, partim, p. 160, fig. 8O.

  • Remarks and comparison. Punctatisporites subtritus Playford & Helby, 1968 is a conspicuous component of the palynoflora and is distinguishable from the accompanying P. lucidulus Playford & Helby, 1968 by its generally much larger size and thicker, intragranulate/ intrapunctate exine. It is commonly preserved as off-polar compressions.

  • Dimensions (32 specimens). Equatorial diameter 57 (88) 112µm.

  • Previous records. Punctatisporites subtritus and P. lucidulus share closely comparable stratigraphic and palaeogeographic distributions (q.v. Playford and Mory 2017, p. 281).

  • Infraturma RETUSOTRILETI Streel in Becker, Bless, Streel & Thorez, 1974
    Genus Retusotriletes Naumova, 1953 emend. Streel, 1964

  • Type species. Retusotriletes simplex Naumova, 1953 [SD; Potonié 1958, p. 13].

  • Retusotriletes separatus Playford, 2015
    Plate 1, figure 5

  • Synonymy.

  • 2015 Retusotriletes separatus Playford, p. 7, fig. 3A–K.

  • Remarks. The few specimens encountered conform with the specific diagnosis as per above synonymy.

  • Dimensions (two specimens). Equatorial diameter 49, 56µm.

  • Previous records. From Western Australian sediments bearing the Grandispora maculosa Assemblage (Playford 2015; Playford and Mory 2017), hence correlative with the Mount Johnstone Formation of the present study.

  • Infraturma APICULATI Bennie & Kidston, 1886 emend. R. Potonié, 1956
    Subinfraturma GRANULATI Dybová & Jachovicz, 1957
    Genus Cyclogranisporites R. Potonié & Kremp, 1954

  • Type species. Cyclogranisporites leopoldii (Kremp, 1952) R. Potonié & Kremp, 1954 [OD].

  • Cyclogranisporites firmus Jones & Truswell, 1992
    Plate 1, figures 6–8

  • Synonymy.

  • 1992 Cyclogranisporites firmus Jones & Truswell, p. 163, figs 8S, 9K, L, O–V.

  • Remarks. The numerous specimens of this study are consonant with those diagnosed by Jones and Truswell (1992) and later described by Playford (2015, p. 10, fig. 4J–N).

  • Dimensions (42 specimens). Equatorial diameter 41 (58) 69µm.

  • Previous records. In the Galilee Basin, Queensland, this species was originally reported (Jones and Truswell 1992) as ranging through zones A–D (Upper Mississippian–Lower Permian). Western Australian occurrences (Playford 2015; Playford and Mory 2017) are from strata hosting the Grandispora maculosa Assemblage and hence coeval with the Mount Johnstone Formation studied here. In Western Gondwana, the possible or likely presence of Cyclogranisporites firmus Jones & Truswell, 1992 in the Argentine Carboniferous was noted by Playford (2015, p. 10).

  • Subinfraturma VERRUCATI Dybová & Jachowicz, 1957
    Genus Verrucosisporites Ibrahim, 1933 emend. Smith & Butterworth, 1957

  • Type species. Verrucosisporites verrucosus (Ibrahim, 1932) Ibrahim, 1933 [OD].

  • Discussion. Quantitatively and qualitatively, this acavate, verrucate genus is conspicuously and diversely represented in the study samples. Main interspecific variables are size, spacing, and distribution of verrucae; haptotypic character; exine thickness; and overall dimensions. In some instances, speciation is not entirely unequivocal insofar as a morpho-continuum could conceivably exist among some species (e.g. Verrucosisporites iannuzzii, V. souzai, and V. roncadorense as described and provisionally maintained separately herein). Conversely, V. quasigobbettii – the most abundant representative of the genus in the Mount Johnstone Formation – incorporates an appreciable range of comprehensively verrucate forms that are demonstrably intergradational.

  • Verrucosisporites adgeratus sp. nov.
    Plate 2, figures 1a, b–5a, b

  • Synonymy.

  • 1992 Verrucosisporites nitidus (Naumova; sic) auct. non Playford, 1964; Jones & Truswell, p. 161, fig. 8I.

  • Diagnosis. Spores radial, trilete; amb circular or nearly so. Laesurae distinct, simple, straight, length two-thirds of to almost equalling spore radius. Exine 1–2 µm thick, sculptured proximally and on marginal distal region with discrete or basally coalescent verrucae up to 6 µm apart. Verrucae circular, subcircular, or roundly polygonal in basal outline; 1.5–6.5 µm broad at base, height 0.8–2 µm. Distinct pole-centred area essentially devoid of sculpture, occupying ca. one-third to three-quarters of distal face, and bordered by circular to subcircular disposition of verrucae.

  • Dimensions (50 specimens). Equatorial diameter 40 (50) 63µm, sculpture excluded.

  • Holotype. Slide K40/33, L30/3 (Plate 2, figure 1a, b). Distal aspect. Amb circular, diameter 46 µm; distinct, simple laesurae, length almost equal to spore radius; exine 1.7 µm thick; verrucate sculpture well developed, excluding unsculptured circular distal polar area, 32 µm in diameter, circumscribed by rampart-like circlet composed of close-spaced to fused verrucae.

  • Type locality. New South Wales, Balickera excavation, sample A720; Mount Johnstone Formation.

  • Etymology. Latin, adger: rampart.

  • Remarks. This species is readily distinguishable from others of the genus in featuring sculpture-free exine of a well-circumscribed area occupying much of its distal face.

  • Previous records. The single specimen recorded by Jones and Truswell (1992, as per above synonymy) was from an unspecified unit in the Galilee Basin, Queensland.

  • Verrucosisporites aspratilis Playford & Helby, 1968
    Plate 2, figures 6–8

  • Synonymy.

  • 1968 Verrucosisporites aspratilis Playford & Helby, p. 108, pl. 9, figs 3–5.

  • non 2012 Verrucosisporites aspratilis Playford & Helby 1968; Playford & Melo, p. 21, pl. 3, figs 8, 9.

  • Description. Spores radial, trilete with circular to very broadly rounded subtriangular amb. Laesurae distinct, simple, straight, length at least two-thirds of spore radius, uncommonly extending almost to equator. Exine 1.5–2.2 µm thick; sculptured comprehensively with mostly discrete verrucae commonly 2–4 µm apart. Verrucae subcircular to roundly or irregularly elongate in basal outline, basal diameter ca. 1–5.5 µm, height 0.5–3 µm. Few grana and minute coni interspersed among verrucae in some specimens.

  • Dimensions (17 specimens). Equatorial diameter, excluding sculptural projections, 40 (55) 66 µm.

  • Previous records. From the Mount Johnstone Formation, New South Wales (Playford and Helby 1968), and to the north in the Galilee Basin (zones A–D, Upper Mississippian through Lower Permian; Jones and Truswell 1992). Playford and Melo (2012, p. 21) noted other records from elsewhere in Gondwana, but the specimen they illustrated reflected a sensu lato perspective of the species; it is here considered probably attributable to Verrucosisporites souzai di Pasquo in di Pasquo and Iannuzzi, 2014 (described below).

  • Verrucosisporites basiliscutis Jones & Truswell, 1992
    Plate 2, figure 9a, b

  • Synonymy.

  • 1992 Verrucosisporites basiliscutis Jones & Truswell, p. 161, fig. 8C, E–H, J–L.

  • Description. Spores radial, trilete. Amb circular to subcircular. Laesurae perceptible to distinct, simple, straight, length one- to two-thirds of spore radius. Exine 1.5–3.5 µm thick, sculptured densely, uniformly, and comprehensively with discrete, close-spaced verrucae ca. 0.5–1 µm apart, thereby defining negative reticulum; basal diameter of verrucae mostly 1.5–2.5 µm, basal outline variable (circular, subcircular, ovaloid, polygonal, irregularly elongate), height 0.5–0.8 µm.

  • Dimensions (12 specimens). Equatorial diameter 39 (50) 61µm.

  • Remarks. See Playford (2015, p. 11).

  • Previous records. Reported initially by Jones and Truswell (1992) from the Upper Mississippian through Lower Permian (zones A–D) of the Galilee Basin, Queensland, and subsequently by Playford (2015) and Playford and Mory (2017) from Western Australian strata of the northern Perth Basin and contiguous Carnarvon Basin containing the Grandispora maculosa Assemblage.

  • Verrucosisporites gregatus Playford & Melo, 2012
    Plate 2, figures 10, 11

  • Synonymy.

  • 2012 Verrucosisporites gregatus Playford & Melo, p. 23, pl. 4, figs 4–11.

  • 2014 Verrucosisporites roncadorense di Pasquo in di Pasquo & Iannuzzi (partim), p. 419, fig. 7.8 (only).

  • Description. Spores radial, trilete, with circular or subcircular amb. Laesurae commonly indistinct, simple, straight, length at least two-thirds of spore radius. Exine sculptured irregularly, on distal surface and less prominently on proximal surface, with variably shaped, mostly discrete verrucae 1–3 µm high; basal outlines of verrucae subcircular to irregularly rounded-polygonal, 2–12 µm in maximum width; height of verrucae 0.8–3 µm, spaced up to 10 µm apart. Unsculptured exine 1.5–3 µm thick.

  • Dimensions (16 specimens). Equatorial diameter 40 (44) 52µm.

  • Remarks. As noted by Playford and Melo (2012) and Playford and Mory (2017), Verrucosisporites gregatus Playford & Melo, 2012 is commonly preserved as partial or complete tetrads.

  • Previous records. This species has been recorded widely from Middle–Upper Mississippian strata of Western, Eastern, and Northern Gondwana (q.v. Playford and Melo 2012, p. 23; Playford 2015, p. 11; Playford and Mory 2017, p. 286).

  • Verrucosisporites iannuzzii di Pasquo in di Pasquo & Iannuzzi, 2014
    Plate 2, figures 12–15; Plate 3, figures 1a, b–3

  • Synonymy.

  • 2014 Verrucosisporites iannuzzii di Pasquo in di Pasquo & Iannuzzi, p. 415, 419, fig. 7.1–4.

  • 2014 Verrucosisporites souzai di Pasquo in di Pasquo & Iannuzzi (partim), p. 419, fig. 7.7 (only).

  • Description. Spores radial, trilete. Amb circular to subcircular. Distinct, simple, straight laesurae extending ca. two-thirds to three-quarters of distance to equator. Exine 1.2–2.5 µm thick, bearing relatively fine and irregular verrucate sculpturing elements both distally and proximally. Verrucae variable in basal outline (subcircular, irregularly elongate, or subpolygonal), maximum width 1.2–3.5 µm, height up to 1.2 µm; mainly discrete, up to ca. 2.5 µm apart.

  • Dimensions (47 specimens). Equatorial diameter 38 (49) 62µm.

  • Remarks and comparison. This species and Verrucosisporites souzai, both instituted by di Pasquo (in di Pasquo and Iannuzzi 2014), are clearly very similar, perhaps conspecific via morphological intergradation. A possible distinction is that the V. iannuzzii is more finely/less obtrusively and more densely verrucate than V. souzai.

  • Previous records. From the Poti Formation (Mag zone; late Visean) in the Parnaíba Basin, north-eastern Brazil (di Pasquo and Iannuzzi 2014).

  • Verrucosisporites italiaensis Playford & Helby, 1968
    Plate 4, figures 13–15

  • Synonymy.

  • 1968 Verrucosisporites italiaensis Playford & Helby, p. 108, pl. 9, figs 15, 16.

  • 2017 Verrucosisporites sp. cf. V. italiaensis Playford & Helby, 1968; Playford & Mory, p. 288, pl. 2, fig. 10.

  • Description. Spores radial, trilete. Amb circular to subcircular (commonly irregularly so due to large-scale exinal folding). Laesurae distinct to perceptible, simple or with minor lip development, length one-half to three-quarters of spore radius. Exine 2–3.5 µm thick, bearing comprehensive, ± uniform, and dense verrucate sculpture. Verrucae rounded in profile; basal outline circular to subcircular, uncommonly lobate; basal diameter 1–4.5 µm; height 1.2–4 µm; mostly discrete and ca. 1–2 µm apart (uncommonly up to 9 µm apart).

  • Dimensions (16 specimens). Equatorial diameter 62 (94) 128µm.

  • Remarks. The specimens figured by Playford and Mory (2017; q.v. above synonymy) were given only a cf. specific designation because the equatorial diameter of their three specimens fell well below the size range stated by Playford and Helby (1968) for Verrucosisporites italiaensis. However, topotypic specimens described above effectively bridge the apparent dimensional disparity.

  • Previous records. Mount Johnstone Formation, New South Wales, and approximately coeval core sample from the Coolcalalaya Sub-basin, Western Australia (Playford and Mory 2017).

  • Verrucosisporites johnstonense sp. nov.
    Plate 3, figures 12–15

  • Diagnosis. Spores radial, trilete, with circular to subcircular amb. Laesurae distinct, simple, straight, extending at least two-thirds of distance to equator. Exine 2.3–3.2 µm thick with comprehensive, somewhat loosely distributed verrucate sculpture. Verrucae 0.5–12 µm apart; basal outlines circular, subcircular, or (much less commonly) rounded-elongate; basal diameter 1.5–6 µm; height 1.3–4 µm. Some specimens with rare grana interspersed among verrucae.

  • Dimensions (20 specimens). Equatorial diameter 62 (69) 78µm (sculpture excluded).

  • Holotype. Slide K40/33, M29/1 (Plate 3, figure 12). Distal aspect. Amb near-circular, diameter 66 µm; laesurae distinct, simple, ± straight, length ca. four-fifths of spore radius; comprehensively distributed, predominantly discrete verrucae 1.5–3 µm high, bases mostly circular to subcircular in outline, diameter 2–4 µm, up to 12 µm apart (mostly ca. 4 µm); exine 2.5 µm thick.

  • Type locality. New South Wales, Balickera excavation, sample A720; Mount Johnstone Formation.

  • Etymology. After the Mount Johnstone Formation.

  • Comparison. Verrucosisporites johnstonense sp. nov. is similar to V. quasigobbettii Jones & Truswell, 1992 (recorded below), but is distinguishable mainly in featuring more uniform, commonly finer, and less crowded verrucae.

  • Verrucosisporites pavimentatus sp. nov.
    Plate 3, figures 8–11

  • Diagnosis. Spores radial, trilete, with circular to subcircular amb. Laesurae distinct, simple, length ca. 0.5–0.7 of spore radius. Exine 1–2 µm thick, bearing comprehensively distributed, closely set, discrete verrucae, broadly rounded in profile to almost flat topped, 1–2 µm high; variably shaped (in plan view: irregularly polygonal, rectangular, elongate, subcircular; ca. 1–10 µm in maximum dimension); negative reticulum resulting from close spacing of verrucae (0.1–3.5 µm apart, commonly ca. 1 µm).

  • Dimensions (21 specimens). Equatorial diameter, excluding sculpture, 45 (52) 59 µm.

  • Holotype. Slide K40/11, W57/3 (Plate 3, figure 8). Proximal aspect. Amb subcircular, 48 µm in diameter; distinct, simple laesurae ca. one-half spore radius in length; exine 1 µm thick, with comprehensive verrucate sculpture; verrucae close-spaced distally, slightly lesser so proximally, defining negative reticulum; verrucae < 1.4 µm apart, very variable basal outline (mostly irregularly polygonal, rectangular, subcircular; maximum breadth 2–8 µm), obtusely rounded in profile, height up to 1.5 µm.

  • Type locality. New South Wales, Balickera excavation, sample A720; Mount Johnstone Formation.

  • Etymology. Latin, pavimentatus: furnished with pavement.

  • Comparison. This species shows scant resemblance to other members of the genus, by reason of the distinctive pavement-like configuration of its sculpturing elements. Verrucosisporites sp. A of Playford and Melo (2012, p. 27, pl. 5, figs 4a, b) has a thicker exine with less variable, more protrusive, and less confined verrucae, particularly in contact areas.

  • Verrucosisporites quasigobbettii Jones & Truswell, 1992
    Plate 4, figures 1a, b–12a, b

  • Synonymy.

  • 1968 Verrucosisporites sp. cf. V. gobbettii Playford & Helby, p. 108–109, pl. 9, figs 6, 7.

  • 1992 Verrucosisporites quasigobbettii Jones & Truswell, p. 161, fig. 8N, P, Q.

  • 1992 Verrucosisporites sp. Jones & Truswell, p. 161, 163, fig. 8M, ?R.

  • 2012 Verrucosisporites quasigobbettii Jones & Truswell, 1992; Playford & Melo, p. 26–27 (cum syn.), pl. 5, figs 7–9.

  • Description. Spores radial, trilete. Amb circular to subcircular or (less frequently) broadly rounded subtriangular; commonly modified irregularly by protrusive verrucae. Laesurae distinct, simple, straight, ca. two-thirds to four-fifths of spore radius in length. Exine 2–4 µm thick, with prominent, well-developed verrucate sculpture borne ± irregularly over proximal and distal surfaces. Verrucae mostly discrete and rounded (less commonly ± pila-like) in profile; basal outline variable, mainly circular, subcircular, or (infrequently) irregularly roundly polygonal, maximum basal width 2.5–14 µm, height 1–6 µm, basal separation commonly 4–8 µm, but may attain as much as 15 µm.

  • Dimensions (100 specimens). Equatorial diameter (excluding sculptural projections) 35 (54) 76 µm.

  • Remarks. The above description, based on the prolific representation of Verrucosisporites quasigobbettii Jones & Truswell, 1992 in the Mount Johnstone Formation samples, essentially replicates that given by Playford (2015, p. 13, fig. 5G–T) from correlative subsurface deposits of the Coolcalalaya Sub-basin, Western Australia. Those accounts together demonstrate the morpho-continuum linking specimens which, if encountered in appreciably lesser abundance, might be (mis)construed as constituting two or even more form species.

  • Previous records. First reported (Playford and Helby 1968) from the Mount Johnstone Formation of the present study, and subsequently by Jones and Truswell (1992) from the Galilee Basin, Queensland, in strata incorporating their zones A–E (uppermost Mississippian through Lower Permian) and by Playford (2015, as cited above). Recorded widely elsewhere in extra-Australian Gondwanan deposits mainly attributed to the Upper Mississippian (Playford and Melo 2012, p. 26–27; Playford 2015, p. 13).

  • Verrucosisporites souzai di Pasquo in di Pasquo & Iannuzzi, 2014
    Plate 3, figures 4–7

  • Synonymy.

  • cf. 2012 Verrucosisporites aspratilis auct. non Playford & Helby, 1968; Playford & Melo, p. 21, pl. 3, figs 8, 9.

  • 2014 Verrucosisporites souzai di Pasquo in di Pasquo & Iannuzzi, p. 419 (partim), fig. 7.5, 6, 11–13 (non fig. 7.7).

  • Description. Spores radial, trilete. Amb circular to subcircular with entire or slightly/irregularly undulating margin. Laesurae distinct, simple, straight, length ca. two-thirds to three-quarters of spore radius. Exine 2–3 µm thick; sculptured comprehensively and somewhat loosely with low verrucae of disparate shape (basal outline pentagonal, triangular, subcircular, elongate) and size (maximum basal diameter mostly 1.5–3.5 µm; height 0.5–2 µm); spacing between verrucae ca. 1–3 µm.

  • Dimensions (25 specimens). Equatorial diameter 33 (51) 62 µm.

  • Remarks. While generally larger (thus extending the size range), these specimens are in close morphological accord with Verrucosisporites souzai di Pasquo in di Pasquo & Iannuzzi, 2014. As mentioned above, this species could conceivably be merged with V. iannuzzii.

  • Previous records. Verrucosisporites souzai was described from the upper Visean Poti Formation, Parnaíba Basin, in Brazil's north-east (di Pasquo and Iannuzzi 2014).

  • Subinfraturma NODATI Dybová & Jachowicz, 1957
    Genus Anapiculatisporites R. Potonié & Kremp, 1954

  • Type species. Anapiculatisporites isselburgensis R. Potonié & Kremp, 1954 [OD].

  • Anapiculatisporites amplus Playford & Powis, 1979
    Plate 5, figures 14–16

  • Synonymy.

  • 1979 Anapiculatisporites amplus Playford & Powis, p. 381–382, pl. I, fig. 8, pl. II, figs 1–5.

  • Remarks. The few specimens recorded here conform to those described by previous authors, most recently Playford and Mory (2017, p. 288, pl. 4, figs 9–12).

  • Dimensions (six specimens). Equatorial diameter, excluding apiculate projections, 60 (88) 113 µm.

  • Previous records. Reported hitherto from Gondwanan strata of Visean through early Pennsylvanian age (Playford and Melo 2012, p. 27; Playford and Mory 2017, p. 288).

  • Anapiculatisporites concinnus Playford, 1962
    Plate 5, figures 10–13

  • Synonymy.

  • 1962 Anapiculatisporites concinnus Playford, p. 587–588, pl. 80, figs 9–12.

  • 2012 Anapiculatisporites concinnus Playford, 1962; Playford & Melo 2012, p. 28–29 (cum syn.), pl. 6, figs 1–4.

  • Description. Spores radial, trilete. Amb subtriangular; apices obtusely (commonly) to acutely rounded, sides nearly straight, slightly concave, or slightly convex. Laesurae distinct, ± straight, extending three-quarters to four-fifths of distance to equator, simple or with slight, narrow lip development. Exine 0.8–1.5 µm thick; entire proximal surface and marginal interradial regions of distal surface laevigate. Remainder (i.e. bulk) of distal surface sculptured with small, discrete, scattered coni, 1–1.5 µm high, bases 1–1.5 µm in diameter and 0.5–2.5 µm apart, ± evenly distributed; uncommonly projecting from equatorial radii (i.e. from amb apices).

  • Dimensions (10 specimens). Equatorial diameter 31 (40) 50 µm.

  • Previous records. As noted by Playford and Melo (2012, p. 29), Anapiculatisporites concinnus Playford, 1962 is widely distributed globally, with first appearances in the Visean and extending, particularly in Gondwanan regions, into the Lower Permian. A recent report of the species is from the Paganzo Basin (Argentina) in strata dated (by U-Pb CA-IDTIMS/Refined Chemical Abrasion-Isotope Dilution Thermal Ionisation Mass Spectrometry) as late Serpukhovian–Bashkirian (Césari et al. 2019).

  • Anapiculatisporites hispidus Butterworth & Williams,1958
    Plate 5, figures 8, 9

  • Synonymy.

  • 1958 Anapiculatisporites hispidus Butterworth & Williams, p. 364, pl. I, figs 30, 31.

  • Description. Spores radial, trilete, with subtriangular amb. Laesurae distinct, simple or flanked by minor marginal folds, length 0.6–0.8 of spore radius. Exine ca. 1 µm thick, proximally laevigate. Distal exine bearing discrete apiculate projections (coni and short spinae), 1.5–3 µm in length, bases 0.8–1.2 µm broad, 1–2 µm apart. Projections shortening towards equator.

  • Dimensions (four specimens). Equatorial diameter, excluding sculptural projections, 35, 38, 40, 45 µm.

  • Remarks. Specimens are commonly preserved as lateral compressions, as in the Scottish type material.

  • Previous records. From the Upper Mississippian–Lower Pennsylvanian of Europe (e.g. Butterworth and Williams 1958; Smith and Butterworth 1967; Jachowicz 1972; Owens et al. 1977, 2004; Kmiecik 1978, 1986) and from an ?upper Visean core sample from the Gulf of Suez region (Sultan 1986).

  • Anapiculatisporites robertsii sp. nov.
    Plate 5, figures 1a, b–5

  • Diagnosis. Spores radial, trilete. Amb roundly subtriangular to subcircular, apices commonly broadly obtuse, sides convex to almost straight. Laesurae perceptible to ± distinct, straight to slightly undulant; with or without narrow lips; commonly extending almost to equatorial margin with ± indistinct curvaturate termini. Exine thin, not exceeding ca. 1 µm in thickness. Distal surface sculptured with very fine, discrete, apiculate elements (minute coni and spinae) 0.5–1.6 µm high, 0.4–0.8 µm in basal diameter, loosely/variably distributed (bases ca. 0.7–4 µm apart). Apices of elements variable when viewed via ×100 oil-immersion objective: acute, slightly expanded (‘knobbly'), uncommonly ± truncate. Proximal surface essentially laevigate, commonly showing slight darkening (polar-centred, indistinctly defined thickening).

  • Dimensions (31 specimens). Equatorial diameter 30 (43) 58µm.

  • Holotype. Slide K30/1, O33 (Plate 5, figure 3a, b). Distal aspect. Amb roundly subtriangular, sides straight to convex, diameter 40µm; very narrowly lipped laesurae extending close to equator with minor, weakly defined curvaturae imperfectae; exine ca. 0.9µm thick; minute apiculate elements (coni, spinae) loosely dispersed over distal surface, very few projecting equatorially.

  • Type locality. New South Wales, Balickera excavation, sample A707; Mount Johnstone Formation.

  • Etymology. In memoriam, Professor Emeritus John Roberts (1938–2018), major contributor to knowledge of Australian Carboniferous stratigraphy and palaeontology, particularly of the southern NEO; q.v. Pickett et al. (2018), Metcalfe (2018).

  • Remarks and comparison. Anapiculatisporites robertsii sp. nov. is distinguished by its minute apiculate elements projecting from the distal surface, and, more sparsely, equatorially; and by the variable nature of the projections' apical termini. The species shows some similarity to Stenozonotriletes coronatus Sullivan & Marshall, 1966 (p. 273, pl. 3, figs 1–5) but differs in being acingulate.

  • Genus Dibolisporites Richardson, 1965 emend. Playford, 1976

  • Type species. Dibolisporites echinaceus (Eisenack, 1944) Richardson, 1965 [OD].

  • Dibolisporites disfacies Jones & Truswell, 1992
    Plate 5, figures 6, 7

  • Synonymy.

  • 1992 Dibolisporites disfacies Jones & Truswell, 1992, p. 167 (partim), fig. 11 A–F, I, J (non fig. 11 G, H, K–M).

  • 2015 Dibolisporites disfacies Jones & Truswell, 1992; Playford, p. 14–15 (cum syn.), fig. 6 A–L.

  • Remarks. Rarely encountered during the present study, this species is characterised by indistinctness or absence of proximal face, together with conspicuous distal sculpture of biform apiculate projections as described by Jones and Truswell (1992) and Playford (2015).

  • Dimensions (seven specimens). Equatorial diameter 46 (49) 56 µm, excluding sculpture.

  • Previous records. As summarised by Playford (2015, p. 15), Dibolisporites disfacies Jones & Truswell, 1992 is known widely and exclusively from Gondwanan strata ranging from Upper Mississippian through Lower Permian.

  • Subinfraturma BACULATI Dybová & Jachowicz, 1957
    Genus Raistrickia Schopf, Wilson & Bentall, 1944
    emend. R. Potonié & Kremp, 1954

  • Type species. Raistrickia grovensis Schopf in Schopf, Wilson & Bentall, 1944 [OD].

  • Raistrickia accincta Playford & Helby, 1968
    Plate 7, figures 1–4

  • Synonymy.

  • 1968 Raistrickia accincta Playford & Helby, p. 109, pl. 9, figs 13, 14.

  • 2017 Raistrickia accincta Playford & Helby, 1968; Playford & Mory, p. 291–292 (cum syn.), pl. 4, fig. 1.

  • Description. Spores radial, trilete, with subcircular to ovaloid amb. Laesurae simple, ± straight, extending two-thirds to four-fifths of distance to equator. Exine 1–2 µm thick; sculptured comprehensively with blunted heterogeneous projections comprising pila (predominantly), together with bacula, coni, and verrucae. Projections having circular to subcircular to rounded-polygonal bases ca. 1–5 µm in diameter, length 1–9 µm, basal separation up to 6 µm (commonly ca. 1–2 µm).

  • Dimensions (16 specimens). Equatorial diameter, excluding sculptural projections, 33 (38) 45 µm.

  • Previous records. Playford and Helby (1968) first described Raistrickia accincta from the Mount Johnstone Formation; it was recently reported from age-equivalent (mid to late Visean) sediments of the northern Perth Basin and the Carnarvon Basin, Western Australia (Playford and Mory 2017). Two specimens figured as R. accincta by Kora (1993, pl. 2, figs 11, 12) from the putative Lower Pennsylvanian of Sinai, Egypt, may be authentic representatives of the species, but the photomicrographs lack clarity. The same would seem applicable to specimens from the Serpukhovian–lower Bashkirian of the Paganzo Basin, Argentina (Césari et al. 2019, fig. 7.12; Colombi et al. 2018, fig. 15, f–h).

  • Raistrickia corymbiata Playford in Playford & Mory, 2017
    Plate 7, figures 5, 6

  • Synonymy.

  • 1968 Raistrickia radiosa Playford & Helby, 1968, p. 109 (partim), pl. 9, fig. 8 (only).

  • 2002 Raistrickia sp. cf. R. accincta Playford & Helby, 1968; Césari & Limarino, p. 166, fig. 5D, G, H.

  • 2017 Raistrickia corymbiata Playford in Playford & Mory, p. 292 (cum syn.), pl. 5, figs 1–5.

  • Description. Spores radial, trilete. Amb circular to subcircular to ovoid or roundly subtriangular. Laesurae distinct to perceptible, simple, straight, extending at least three-quarters of distance to equator. Exine ca. 1.5 µm thick, proximally laevigate or scabrate. Relatively short, squat, terminally expanded projections (pila) distributed over entire distal surface and projecting equatorially. Pila ± uniformly spaced (uncommonly conjoined) on given specimen, but variable among specimens (up to 5 µm apart); height and basal diameter of pila likewise ± uniform on individual specimen but variable among specimens (1.5–4.5 µm); bases circular to subcircular in outline; terminal expansion (caput) 2–4 µm in diameter.

  • Dimensions (32 specimens). Equatorial diameter, excluding sculptural projections, 39 (64) 100 µm.

  • Comparison. See Playford and Mory (2017, p. 292).

  • Previous records. From Australian middle to late Visean sediments containing the Grandispora maculosa palynoflora (Playford and Helby 1968; Playford 2015, misidentified as R. accincta, q.v. Playford & Mory, 2017).

  • Raistrickia radiosa Playford & Helby, 1968
    Plate 7, figures 7, 8

  • Synonymy.

  • 1968 Raistrickia radiosa Playford & Helby, p. 109–110, pl. 9, figs 9, 10 (non fig. 8).

  • Description. Spores radial, trilete with circular to roundly subtriangular amb. Laesurae indistinct to perceptible, simple, two-thirds to three-quarters of spore radius in length. Exine, where unsculptured, 1.5–2.5µm thick. Distal and proximo-equatorial exine bearing sculptural projections – bacula (mainly), also blunted spinae – 1–10µm in length; sides parallel or slightly tapering towards truncate, bluntly rounded, or very weakly expanded tops; bases circular to subcircular in outline, diameter ca. 1–4.5µm. Reduced sculpture on contact faces: commonly low irregular verrucae to almost laevigate or scabrate.

  • Dimensions (27 specimens). Equatorial diameter, excluding sculptural projections, 53 (74) 101 µm.

  • Comparison. See Playford and Helby (1968, p. 109–110) and Playford and Mory (2017, p. 292).

  • Previous records. This species has been identified in strata within the Visean–Pennsylvanian interval of Eastern and Western Gondwana (Playford 2015, p. 16).

  • Infraturma MURORNATI R. Potonié & Kremp, 1954
    Genus Brochotriletes Naumova, 1939 ex Ishchenko, 1952

  • Type species. Brochotriletes magnus Ishchenko, 1952 [M].

  • Brochotriletes diversifoveatus Playford & Satterthwait, 1985
    Plate 6, figure 9a, b

  • Synonymy.

  • 1985 Brochotriletes diversifoveatus Playford & Satterthwait, p. 141, pl. 4, figs 3–5.

  • 2012 Brochotriletes diversifoveatus Playford & Satterthwait, 1985; Playford & Melo, p. 40–41 (cum syn.), pl. 13, fig. 6.

  • Description. Spores radial, trilete, with circular to convexly subtriangular amb. Laesurae ± distinct, simple, straight, length two-thirds to four-fifths of spore radius. Exine 3–4.5 µm thick; comprehensively incised to depths of 2.5–3.5 µm with foveolae (principally) and minor vermiculi. Foveolae of irregular shape in plan view (subcircular to roundly polygonal/elongate), 1–15 µm in maximum dimension, 1–9 µm apart.

  • Dimensions (six specimens). Equatorial diameter 63 (67) 74µm.

  • Previous records. Reported from northern and Western Australian strata of mid Visean–early Serpukhovian age (Playford and Satterthwait 1985; Playford and Mory 2017); from coeval strata of the Amazonas and Parnaíba basins, northern Brazil (Playford and Melo 2012); and likely from the Algerian Sahara (Lanzoni and Magloire 1969, pl. II, figs 4, 5).

  • Genus Convolutispora Hoffmeister, Staplin & Malloy, 1955

  • Type species. Convolutispora florida Hoffmeister, Staplin & Malloy, 1955 [OD].

  • Convolutispora perplicata sp. nov.
    Plate 7, figures 16–18

  • Diagnosis. Spores radial, trilete with circular to subcircular amb. Laesurae perceptible to ± distinct; length ca. two-thirds to three-quarters of spore radius. Exine 1.2–1.8 µm thick where unsculptured. Comprehensive murornate sculpture comprising muri/rugulae 0.5–2.5 µm wide, both freely terminating and anastomosing, 0.7–1.2 µm high, 0.5–5 µm apart.

  • Dimensions (23 specimens). Equatorial diameter 45 (59) 72 µm overall.

  • Holotype. Slide K40/12, D58/1 (Plate 7, figure 17). Proximal aspect. Amb subcircular, diameter 53 µm; laesurae discernible, straight, simple, length ca. 0.7 of spore radius; exine 1.3 µm thick, bearing convolute to rugulate sculpture distally and proximally; muri anastomosing and freely terminating, 0.5–1 µm wide, 0.7–1 µm high, 0.5–3.5 µm apart.

  • Type locality. New South Wales, Balickera excavation, sample A720; Mount Johnstone Formation.

  • Etymology. Latin, perplicatus: intricate, entangled.

  • Comparison. Convolutispora venusta Hoffmeister, Staplin & Malloy, 1955 (p. 385, pl. 38, fig. 11) and C. perplicata sp. nov. are similar, but the latter is differentiable mainly in possessing less crowded and more variable murornate sculpture and probably a somewhat thinner exine. Convolutispora sp. A of Playford (1971, p. 28, pl. 9, fig. 6) is larger and more densely and uniformly rugulate than C. perplicata.

  • Dimensions (23 specimens). Equatorial diameter 45 (59) 72 µm overall.
    Genus Cordylosporites Playford & Satterthwait, 1985

  • Type species. Cordylosporites sepositus Playford & Satterthwait, 1985 [OD].

  • Cordylosporites asperidictyus (Playford & Helby, 1968)
    Dino & Playford, 2002
    Plate 6, figures 15–17

  • Synonymy.

  • 1968 Reticulatisporites asperidictyus Playford & Helby, p. 110, pl. 9, figs 17, 18, pl. 10, fig. 1.

  • 2002 Cordylosporites asperidictyus (Playford & Helby, 1968) Dino & Playford, p. 344–345, pl. 1, figs 8, 9.

  • Description. Spores radial, trilete; amb circular to subcircular. Laesurae perceptible to±distinct, straight, length two-thirds to three-quarters of spore radius. Exine comprehensively reticulate; muri variable in basal width (1.5–4µm) and height (1.5–6.5µm) enclosing subcircular, polygonal, or elliptical lumina 3–20µm in maximum diameter (smaller lumina commonly proximal). Crests of muri fimbriate, being modified by very fine and close-spaced projections (diminutive grana, verrucae, spinae, bacula) < 2µm high). Non-reticulate exine 2–3µm thick.

  • Dimensions (22 specimens). Overall equatorial diameter 55 (65) 75 µm.

  • Previous records. From Eastern Gondwana (Western Australia, New South Wales; Playford and Helby 1968; Playford 2015; Playford and Mory 2017) and Western Gondwana (Brazil, Argentina; q.v. Dino and Playford 2002, p. 345; Perez Loinaze 2009; Perez Loinaze et al. 2010; Perez Loinaze and Césari 2012; Césari et al. 2019; Colombi et al. 2018), in strata mainly of middle Visean–early Serpukhovian age.

  • Genus Foveosporites Balme, 1957

  • Type species. Foveosporites canalis Balme, 1957 [OD].

  • Foveosporites pellucidus Playford & Helby, 1968
    Plate 6, figures 10–14a, b

  • Synonymy.

  • 1968 Foveosporites pellucidus Playford & Helby, p. 111, pl. 10, figs 2–6.

  • Description. Spores radial, trilete, with circular to convexly subtriangular amb. Laesurae simple, straight, ± distinct, extending for two-thirds to four-fifths of distance to equator. Distal and proximo-equatorial exine densely foveo-vermiculate, elements ± regularly/densely distributed, incising exine by ca. 0.5–1.5 µm. Vermiculi simple or branching, non-anastomosing, very narrow (ca. 0.4–0.7 µm wide), up to ca. 10 µm long; foveolae discrete, circular, subcircular, or roundly elongate in outline and 1.5–8.5 µm in maximum diameter. Unsculptured exine 2–3.5 µm thick.

  • Dimensions (39 specimens). Equatorial diameter 50 (64) 80µm.

  • Previous records. Characteristic component of the Grandispora maculosa Assemblage of eastern and Western Australia, and coevally (mid Visean–lower Serpukhovian) in South America (Playford and Melo 2012, p. 49–50).

  • Genus Microreticulatisporites Knox, 1950 emend. R. Potonié & Kremp, 1954 sensu Smith & Butterworth, 1967

  • Type species. Microreticulatisporites lacunosus (Ibrahim, 1933) Knox, 1950 [SD; Potonié & Kremp 1954, p. 143].

  • Microreticulatisporites sp. A Plate 7, figures 13–15

  • Description. Spores radial, trilete; amb circular to subcircular, margin slightly undulant to almost entire. Laesurae perceptible to ± distinct, simple, length two-thirds to three-quarters of spore radius. Exine 1–1.5 µm thick; with fine, comprehensive reticulum perfectum; muri 0.5–1.5 µm wide, 0.5–1.2 µm high, enclosing circular to subcircular lumina 0.7–5 µm in maximum diameter.

  • Dimensions (three specimens). Equatorial diameter 57, 66, 78 µm.

  • Comparison and remarks. Dictyotriletes sp. B of Playford (1978, p. 128, pl. 8, figs 8–10) is smaller than Microreticulatisporites sp. A and its reticulum is vestigial proximally. Microreticulatisporites punctatus Knox, 1950, as described and figured by Perez Loinaze and Césari (2004, p. 420, pl. 3, figs 2, 3), is more finely reticulate than the present form. Although favourably preserved, the three specimens encountered are clearly insufficient for other than informal specific designation.

  • Genus Rattiganispora Playford & Helby, 1968 emend. Playford, 1986

  • Synonymy.

  • 1968 Rattiganispora Playford & Helby, p. 111.

  • 1983 Diademaspora Playford, p. 272–273.

  • 1986 Rattiganispora Playford & Helby, 1968 emend. Playford, p. 85–86.

  • Type species. Rattiganispora apiculata Playford & Helby, 1968 emend. Playford, 1986 [OD; M].

  • Discussion. See Playford (1986, p. 86, 91) and Jones and Truswell (1992, p. 169).

  • Rattiganispora apiculata Playford & Helby, 1968 emend. Playford, 1986
    Plate 7, figures 9a, b–12

  • Synonymy.

  • 1968 Rattiganispora apiculata Playford & Helby, p. 111–112, pl. 11, figs 1–3.

  • 1986 Rattiganispora apiculata Playford & Helby, 1968 emend. Playford, p. 86–91, pl. I, figs 1–9, pl. II, figs 1–7, pl. III, figs 1–6, text-fig. 1a.

  • Description. Spores radial, trilete; amb convexly subtriangular to subcircular. Laesurae perceptible to distinct, ± straight, simple or narrowly lipped, length at least two-thirds of spore radius, commonly extending close to equatorial margin. Contact areas, comprising bulk of proximal face, essentially laevigate. Distal surface featuring (i) a distinct, rounded to somewhat flattened, polar-centred, boss-like prominence, basal outline circular to subcircular, circumscribed by (ii) a continuous, moat-like depression, the latter flanked by (iii) the outer equatorial zone. Depression (ii) laevigate or scabrate; (i) and (iii) finely apiculate, bearing scattered, minute, discrete spinae and coni, 0.5–3 µm long, 0.5–1.2 µm broad basally, 1–10 µm apart. Exine thickness, measured equatorially, 0.6–1.5 µm.

  • Dimensions (40 specimens). Equatorial diameter 32 (39) 46 µm; diameter of distal polar boss 13 (18) 23 µm.

  • Comparison. This species is readily distinguishable from Rattiganispora acuminata (Playford, 1983, p. 273–274, pl. I, figs 1–9, pl. II, figs 1–3) Playford, 1986 (p. 91–92, pl. IV, figs 1–10, text-fig. 1 b) on criteria detailed by Playford (1986).

  • Previous records. In Australia, originally (Playford and Helby 1968) from the Italia Road/Mount Johnstone Formation of this study; subsequently from correlative strata in the Clarke River Basin, Queensland (Playford 1986), and from the Galilee Basin, Queensland, zones C–?E (upper Mississippian–Pennsylvanian: Jones and Truswell 1992). Dino and Playford (2002, p. 345) summarised occurrences reported from Brazil and Argentina. These, together with ensuing South American reports (e.g. Césari and Gutiérrez 2001; Perez Loinaze et al. 2011), signify that Rattiganispora apiculata has a closely comparable chronostratigraphic range in Eastern and Western Gondwana.

  • Genus Reticulatisporites Ibrahim, 1933 emend. R. Potonié & Kremp, 1954

  • Type species. Reticulatisporites reticulatus (Ibrahim, 1932) Ibrahim, 1933 [OD].

  • Reticulatisporites magnidictyus Playford & Helby, 1968 emend. Playford, 2017
    Plate 6, figures 1–8

  • Synonymy.

  • 1968 Reticulatisporites magnidictyus Playford & Helby, p. 110–111, pl. 10, figs 7–10.

  • 2017 Reticulatisporites magnidictyus Playford & Helby, 1968 emend. Playford, p. 5 (cum syn.), fig. 2a, b; pl. 1, figs 1–12; pl. 2, figs 1–11.

  • Remarks. The recent diagnostic emendation (Playford, 2017) is based on many more specimens than originally examined by Playford and Helby (1968). Accordingly, it constitutes an appreciably broader morphological spectrum (Playford 2017, pls 1, 2; pl. 6, figs 1–8 herein). Main variables are overall size; reticulum (strongly developed to, much less commonly, vestigial); and complete absence (commonly) or presence of perceptible to well-developed pronged apical prominence (cf. Playford 2017, pl. 2; pl. 6, figs 7, 8 herein).

  • Dimensions (270 specimens). Equatorial diameter, excluding reticulum, 64 (94) 130µm. Note. This incorporates 200 specimens measured during the present study plus the original 20 specimens (Playford and Helby 1968, p. 110) and the 50 topotypic specimens recorded by Playford (2017, p. 5).

  • Previous records. The exceptionally widespread dissemination of this species in Eastern, Western, and Northern Gondwanan strata of mid Visean through early Serpukhovian age – as a characteristic component of the Grandispora maculosa Assemblage and of Melo and Loboziak's (2003) Mag Zone – was documented in Playford (2017, p. 6–7, figs 1, 3). A subsequent record by Césari et al. (2019) is from the Paganzo Basin (Argentina) in strata attributed to their Stage 5 (dated as Bashkirian).

  • Subturma ZONOTRILETES Waltz in Luber & Waltz, 1938 Infraturma TRICRASSATI Dettmann, 1963
    Genus Diatomozonotriletes Naumova, 1939 emend. Playford, 1963

  • Type species. Diatomozonotriletes saetosus (Hacquebard & Barss, 1957) Hughes & Playford, 1961 [SD; Playford 1963, p. 646].

  • Diatomozonotriletes sp. A Plate 9, figure 1

  • Description. Spore radial, trilete. Amb subtriangular with obtusely rounded apices and straight to slightly concave sides. Laesurae perceptible, straight, extending to near-vicinity of equator, partly flanked by low, narrow, discontinuous exinal folds or thickenings. Exine ca. 1µm thick, proximal surface essentially laevigate. Distal surface sculptured with discrete, minute coni-spinae up to 1.5 µm long, 0.7–1.4 µm broad basally, 1–3 µm apart. Equatorially coronate: each interradial region marked by a single row of discrete spinae up to 3.5 µm long and 1.2 µm broad basally, in central inter-radii, gradually diminishing towards amb apices near or where minute coni (ca. 0.5 µm high) are present.

  • Dimensions (one specimen). Equatorial diameter, excluding corona, 68 µm.

  • Comparison and remarks. This single incomplete but otherwise well-preserved specimen appears to show no close resemblance to previously instituted species of the genus. The clear size distinction between the distal apiculate projections and those of the equatorial corona warrants the generic assignment, rather than to Tricidarisporites Sullivan & Marshall, 1966 emend. Gueinn, Neville & Williams in Neves et al., 1973.

  • Infraturma CINGULATI R. Potonié & Klaus, 1954 emend. Dettmann, 1963
    Genus Knoxisporites R. Potonié & Kremp, 1954 emend. Neves, 1961

  • Type species. Knoxisporites hagenii R. Potonié & Kremp, 1954 [OD].

  • Knoxisporites balickeraensis sp. nov. Plate 8, figures 3a, b–8

  • Diagnosis. Spores radial, trilete. Amb variably triangular, subtriangular, quadrilateral; periphery entire, undulating, or with commonly irregular, broad-based projections. Laesurae distinct, simple, straight, extending for ca. three-quarters of distance to equator. Cingulum of uniform or variable width, within range of 2.5–10 µm. Distal surface bearing a continuous or near-continuous ridge, 2.5–7 µm wide, encompassing a substantial polar region and with outline conforming to equator. Proximal surface largely scabrate or minutely granulate; proximo-equatorial and distal surfaces densely granulate with elements mostly < 1 µm in height and basal diameter.

  • Dimensions (10 specimens). Equatorial diameter 34 (46) 56 µm.

  • Holotype. Slide K40/16, X54/1 (Plate 8, fig. 3a, b). Proximal aspect. Equatorial diameter 36 µm; amb subtriangular with convex to almost straight sides, margin entire; distinct, straight, simple laesurae, three-quarters of spore radius in length; exine laevigate to weakly/indistinctly granulate; cingulum 3.5 µm wide; distal circumpolar ridge 3.5–4 µm wide.

  • Type locality. New South Wales, Balickera excavation, sample A720; Mount Johnstone Formation.

  • Etymology. From the rural settlement of Balickera in the Hunter Valley, New South Wales.

  • Comparison. Three main attributes of Knoxisporites balickeraensis sp. nov., separately and together, serve to distinguish it from previously instituted species of the genus – viz., the variable overall amb configuration; the variable equatorial margin of the cingulum (± coarse projections); and the (predominantly distal) granulate sculpture.

  • Knoxisporites sp. A
    Plate 8, figure 1a, b

  • Description. Spore radial, trilete. Amb circular. Laesurae distinct, straight to curved, extending to cingulum's inner margin, with lips 1–1.6 µm wide overall. Exine laevigate. Cingulum uniformly 4.5 µm wide. Distal surface bearing continuous ring-like thickening 3 µm wide circumscribing polar region 23 µm in diameter.

  • Dimensions (one specimen). Overall equatorial diameter 38 µm.

  • Remarks. Only one, albeit well-preserved, specimen was encountered. It appears consonant with Knoxisporites R. Potonié & Kremp, 1954 emend. Neves, 1961, but shows no clear similarity to established species of the genus.

  • Knoxisporites sp. B
    Plate 8, figure 2a, b

  • Description. Spore radial, trilete, with near-circular amb. Laesurae distinct, simple, straight, attaining cingulum's inner margin. Cingulum uniform, very narrow (1.7 µm wide). Distal polar region, 26 µm in diameter, circumscribed by narrow, continuous ring-like thickening 2.5 µm wide. Cingulum and distal ring laevigate; elsewhere exine laevigate to scabrate.

  • Dimensions (one specimen). Overall equatorial diameter 43µm.

  • Comparison. The sole, well-preserved specimen resembles the widely reported Mississippian species Knoxisporites ruhlandii Doubinger & Rauscher, 1966 (p. 384, 386; pl. VI, figs 4–7; pl. pl. VII, figs 1, 2; text-fig. 3), but differs from the latter chiefly in lacking a distal polar boss, and in having a circular amb and simple (unlipped) laesurae.

  • Suprasubturma LAMINATITRILETES Smith & Butterworth, 1967
    Subturma ZONOLAMINATITRILETES Smith & Butterworth, 1967
    Infraturma CINGULICAVATI Smith & Butterworth, 1967
    Genus Densoisporites Weyland & Krieger, 1953 emend Dettmann, 1963

  • Type species. Densoisporites velatus Weyland & Krieger, 1953 emend. Krasnova in Samoilovitch & Mtchedlishvili, 1961 [OD; M].

  • Densoisporites argutus sp. nov.
    Plate 9, figures 5, 6

  • Diagnosis. Spores radial, trilete, cingulicavate; amb convexly subtriangular. Laesurae distinct, straight to slightly curved, narrowly lipped (1.5–2.5 µm wide overall), extending almost to equator. Intexine laevigate, 1–1.5 µm thick, forming well-defined inner body with or without marginal folding, outline (in polar aspect) conforming to amb and contracted from spore-cavity margin by up to 6 µm. Exoexine laevigate to scabrate, but outer equatorial region (flange) irregularly or somewhat radially dissected-cum-fimbriate (possible corrosion effect in part).

  • Dimensions (10 specimens). Overall equatorial diameter 52 (68) 84µm; diameter of spore cavity, in polar view, 33 (45) 54µm.

  • Holotype. Slide K30/1, V51/3 (Plate 8, figure 6). Distal aspect. Amb 40 µm in diameter, subtriangular with convex sides and obtuse to rounded-acute apices; laesurae distinct, ± straight, narrowly lipped, almost reaching equatorial margin; laevigate intexine ca. 1 µm thick, outline conformable with amb, slightly excentrically disposed, diameter 38 µm; exoexine scabrate, flange 3–9 µm wide.

  • Type locality. New South Wales, Balickera excavation, sample A707; Mount Johnstone Formation.

  • Etymology. Latin, argutus: distinct, clear.

  • Remarks and comparison. Attribution to the genus is perhaps questionable, given that Densoisporites argutus sp. nov. lacks a uniformly thickened equatorial margin. Of the few established Carboniferous species, D. truswelliae Stephenson, Al Rawahi & Casey, 2008 (q.v. Playford 2015, p. 19–20, fig. 9A–I) differs from the present specimens in its shorter laesurae and distinctly cingulate equatorial margin.

  • Genus Densosporites Berry, 1937 emend. R. Potonié & Kremp, 1954

  • Type species. Densosporites covensis Berry, 1937 [OD].

  • Densosporites infacetus Daemon, 1974
    Plate 9, figures 7, 8

  • Synonymy.

  • 1974 Densosporites infacetus Daemon, p. 569–570, pl. VII, figs 6, 7.

  • 2012 Densosporites infacetus Daemon, 1974; Melo & Playford, p. 107–108 (cum syn.), pl. 3, figs 9–12.

  • Description. Spores radial, trilete, cingulicavate. Amb convexly subtriangular. Laesurae perceptible, simple or with very narrow lips, extending to or close to cingulum's inner margin. Intexine very thin and featureless, variably contracted from exoexine by up to ca. 8 µm. Exoexine laevigate proximally, thickened equatorially to form well-defined cingulum. Distal surface sculptured prominently with discrete or basally coalescent coni and spinae that project equatorially, thus producing a coarsely jagged margin. Sculptural elements broad-based (diameter 3–5 µm), height 4–10.5 µm.

  • Dimensions (eight specimens). Equatorial diameter (excluding sculptural projections) 48 (58) 72 µm; spore-cavity diameter (polar view) 35 (43) 54 µm.

  • Previous records. As summarised by Melo and Playford (2012, p. 108), Densosporites infacetus Daemon, 1974 has been reported principally from the uppermost Devonian–Mississippian of the Amazonas Basin, northern Brazil, and from the Strunian of the Algerian Sahara (Lanzoni and Magloire 1969).

  • Densosporites sp. A
    Plate 9, figures 9a, b, 10

  • Description. Spores radial, trilete, cingulicavate. Amb subtriangular with convex sides and obtusely to acutely rounded apices. Laesurae distinct to perceptible, straight or weakly undulant, extending to or just beyond inner margin of cingulum, accompanied by very narrow lips (ca. 1 µm wide overall). Proximal surface essentially laevigate. Distal surface of exoexine apiculate: sculptured with spinae and, much less commonly, coni, loosely and irregularly distributed on non-cingulate (polar/subpolar) region; closer spaced, including some basal coalescence, on cingulum and projecting prominently equatorially. Dimensions of sculptural elements: length 2–6.5 µm, bases 0.5–3.5 µm in diameter, up to 4 µm apart. Distal exoexine showing slight thickening in polar region. Intexine very thin, in contact with or slightly contracted from exoexine.

  • Dimensions (five specimens). Equatorial diameter (excluding sculptural projections) 59 (70) 82 µm; cingulum width 5–11 µm.

  • Comparison. These specimens appear to show no close similarity to previously instituted species of the genus, but their numbers are clearly insufficient for formal designation as new. Densosporites spinosus Dybová & Jachowicz, 1957 (p. 164–166, pl. XLIX, figs 1–4) is smaller with a proportionately wider cingulum and more strongly lipped laesurae.

  • Genus Indotriradites Tiwari, 1964 emend. Foster, 1979

  • Type species. Indotriradites korbaensis Tiwari, 1964 [OD].

  • Indotriradites kuttungensis (Playford & Helby, 1968) Playford, 1991
    Plate 9, figures 2–4

  • Synonymy.

  • 1968 Kraeuselisporites kuttungensis Playford & Helby, p. 112–113, pl. 11, figs 6, 7.

  • 1991 Indotriradites kuttungensis (Playford & Helby, 1968) Playford, p. 104.

  • non 1992 Cristatisporites sp. cf. kuttungensis (Playford & Helby, 1968) Jones & Truswell, p. 171, 173, fig. 14 A–F.

  • Remarks. The species' diagnostic features have been amplified and illustrated in detail by Playford (2015, p. 21, fig. 11A–T) based on its abundant representation in the northern Perth Basin, Western Australia.

  • Dimensions (51 specimens). Overall equatorial diameter, excluding spinose projections, 49 (65) 86 µm; diameter of spore cavity, in polar view, 31 (41) 55 µm.

  • Comparison. From the Agua Colorada Formation (Paganzo Basin, Argentina), dated as late Serpukhovian–Bashkirian, Césari et al. (2019, p. 412–413, fig. 6.8–11) recorded abundant specimens of Indotriradites stellatus (Azcuy, 1975) Césari & Perez Loinaze in Césari et al., 2019. While noting its similarity to I. kuttungensis (Playford & Helby, 1968) Playford, 1991 in terms of preservationally variable distal sculpture, Césari et al. (2019, p. 413) stated that favourably preserved specimens of I. stellatus feature ‘spaced acuminate verrucae and bacula’, whereas I. kuttungensis is characterised by ‘a uniform and predominate [sic] spinose sculpture with subordinate coni …'.

  • Previous records. Originally described from the Mount Johnstone Formation by Playford and Helby (1968), and reported subsequently from age-equivalent (Grandispora maculosa-zonal) deposits of the northern Perth Basin and Carnarvon Basin, Western Australia (Playford 2015; Playford and Mory 2017).

  • Genus Radiizonates Staplin & Jansonius, 1964

  • Type species. Radiizonates aligerens (Knox, 1950) Staplin & Jansonius, 1964 [OD].

  • Radiizonates arcuatus Loboziak, Playford & Melo, 2000
    Plate 9, figure 12a, b

  • Synonymy.

  • 2000 Radiizonates arcuatus Loboziak, Playford & Melo, p. 272, 274 (cum syn.), pl. I, figs 1–18.

  • 2012 Radiizonates arcuatus Loboziak, Playford & Melo, 2000; Melo & Playford, p. 113–114 (cum syn.), pl. 6, figs 15–17.

  • Dimensions (two specimens). Overall equatorial diameter 67, 72 µm; spore-cavity diameter, in polar view, 38, 40 µm.

  • Previous records. The two specimens represent the first Australian report of Radiizonates arcuatus Loboziak, Playford & Melo, 2000, which is well known from the Mississippian of Western and Northern Gondwana (Melo and Playford 2012, p. 113–114).

  • Genus Vallatisporites Hacquebard, 1957

  • Type species. Vallatisporites vallatus Hacquebard, 1957 [OD].

  • Vallatisporites sp. cf. V. hystricosus (Winslow, 1962)
    Wicander & Playford, 2013
    Plate 9, figure 13

  • Synonymy.

  • cf. 1962 Cirratriradites hystricosus Winslow, p. 41–42, pl. 18, fig. 5.

  • cf. 1962 Cirratriradites sp. A Winslow, p. 42, pl. 18, figs 1,? 2.

  • cf. 1988 Vallatisporites hystricosus (Winslow) Byvscheva, 1985 (comb. invalid); Avchimovitch, Byvscheva, Higgs, Streel & Umnova, p. 175 (cum syn.), pl. 5, fig. 14.

  • cf. 2006 Vallatisporites hystricosus (Winslow) Byvscheva, 1985; Dueñas & Césari, p. 33, pl. II, fig. 12. [no description]

  • cf. 2013 Vallatisporites hystricosus (Winslow, 1962) Wicander & Playford, p. 614, pl. 6, fig. 1.

  • Description. Spores radial, trilete, cingulicavate. Amb convexly subtriangular. Laesurae ± distinct, simple, straight, extending four-fifths of distance to equator. Intexine ca. 0.5 µm thick, forming distinct internal body slightly contracted from spore-cavity margin. Exoexine forming zona of ± uniform thickness; inner part, constituting ca. 35–50% of zona width, occupied by uniserially disposed, radially elongate to subcircular vacuoles. Proximal exoexine laevigate to scabrate. Distal exoexine sculptured with discrete apiculate elements (predominantly spinae) 2–10 µm long, tapering regularly from circular bases (diameter 1.2–3.5 µm; mostly 2–8 µm apart) to acutely pointed apices; outer equatorial (non-vacuolate) zonal region bearing diminished, scattered elements (short spinae, coni).

  • Dimensions (two specimens). Equatorial diameter 74, 75 µm; diameter of spore cavity (polar view) 44, 51 µm.

  • Remarks and comparison. Of currently recognised species of Vallatisporites Hacquebard, 1957, these two well-preserved specimens most closely resemble V. hystricosus (Winslow, 1962) Wicander & Playford, 2003, but differ in that the apiculate distal exoexine bears more delicate spinae featuring no or only minor basal expansion (i.e. they are essentially nongaleate). The undescribed spore figured by Dueñas and Césari (2006, as per above synonymy) is sculpturally similar to, and could conceivably be conspecific with, the present specimens. Another illustrated but undescribed specimen (Melo and Loboziak 2003, pl. VIII, fig. 7), labelled Vallatisporites hystricosus (Winslow) Byvscheva, 1985, differs mainly in being less prominently vacuolate.

  • None of the spores figured by Kedo and Golubtsov (1971, pl. III, figs 1–19) as Hymenozonotriletes pusillites Kedo, 1957 sensu lato (i.e. including V. hystricosus as synonym) resembles the present specimens or that illustrated by Dueñas and Césari (2006).

  • Previous record. (possible). Dueñas and Césari's (2006) specimen is from the Lower Mississippian of the Llanos Orientales Basin, Colombia.

  • Suprasubturma PSEUDOSACCITITRILETES Richardson, 1965
    Infraturma MONOPSEUDOSACCITI Smith & Butterworth, 1967
    Genus Diaphanospora Balme and Hassell, 1962

  • Synonymy. See Playford (1976, p. 40).

  • Type species. Diaphanospora riciniata Balme and Hassell, 1962 [OD].

  • Diaphanospora sp. A
    Plate 9, figure 11

  • Description Spores radial, trilete. Amb subcircular to convexly subtriangular. Laesurae simple, straight, extending for ca. one-half to two-thirds of distance to intexinal body margin. Exine two-layered, cavate; intexine periphery ± conformable with amb. Intexine laevigate, darker than enveloping exoexine, thickness 1–1.2 µm. Exoexine very thin, ca. 0.5 µm thick, diaphanous, surface finely rugulate to imperfectly reticulate; muri ca. 0.7 µm wide and high; lumina mostly irregularly polygonal, 3–18 µm in maximum dimension.

  • Dimensions (two specimens). Overall equatorial diameter 79, 86 µm; diameter of intexine (polar view) 64, 76 µm.

  • Comparison. This informally designated species shows some resemblance to Diaphanospora angusta? (Hacquebard, 1957) Playford & McGregor, 1993 (p. 36–37, pl. 16, figs 1, 2) but differs mainly in featuring a more finely wrinkled, quasi-reticulate exoexine.

  • Genus Grandispora Hoffmeister, Staplin & Malloy, 1955
    emend. McGregor, 1973

  • Type species. Grandispora spinosa Hoffmeister, Staplin & Malloy, 1955 [OD; M].

  • Grandispora maculosa Playford & Helby, 1968
    Plate 9, figures 14, 15

  • Synonymy.

  • 1968 Grandispora maculosa Playford & Helby, p. 113, pl. 11, figs 4, 5.

  • non 1997 Grandispora maculosa Playford & Helby; Coquel, Loboziak, Stampfli & Stampfli-Vuille, pl. 3, 3. [no description]

  • Remarks. The present topotypic specimens replicate the morphology of this species as detailed originally (Playford and Helby 1968) and subsequently from age-equivalent Western Australian strata (Playford 2015, p. 24, fig. 12A–C).

  • Dimensions (15 specimens). Overall equatorial diameter 34 (52) 74 µm; diameter of intexine (polar view) 28 (43) 63 µm.

  • Previous records. Reported widely from Eastern and Western Gondwanan sediments dated within the Middle–Late Mississippian interval (Melo and Playford 2012, p. 120–121; di Pasquo and Iannuzzi 2014; Playford 2015; Playford and Mory 2017).

  • Genus Velamisporites Bharadwaj & Venkatachala, 1962

  • Synonymy.

  • 1962 Velamisporites Bharadwaj & Venkatachala, p. 24–25.

  • 2012 Velamisporites Bharadwaj & Venkatachala, 1962; Melo & Playford, p. 125 (cum syn.).

  • Type species. Velamisporites rugosus Bharadwaj & Venkatachala, 1962 [OD].

  • Discussion. As posited by Ravn (1991, p. 95–96), and discussed in some detail by Melo & Playford (2012, p. 125–126), Rugospora Neves & Owens (1966, p. 350, 352) is regarded here as a junior synonym of Velamisporites Bharadwaj & Venkatachala, 1962.

  • Velamisporites australiensis (Playford & Helby, 1968) di
    Pasquo, Azcuy & Souza, 2003
    Plate 9, figures 16–18

  • Synonymy.

  • 1968 Wilsonites australiensis Playford & Helby, p. 114–115, pl. 11, figs 15–19.

  • 1992 Rugospora australiensis (Playford & Helby, 1968) Jones & Truswell, p. 175–176, fig. 10 O–T.

  • 2003 Velamisporites australiensis (Playford & Helby) di Pasquo, Azcuy & Souza, p. 290. [no description or illustration]

  • 2009 Velamisporites australiensis (Playford & Helby) di Pasquo, Azcuy & Souza; di Pasquo, pl. 3, fig. F. [no description]

  • Description. Spores radial, trilete, with circular to subcircular amb, less commonly convexly subtriangular. Laesurae distinct or indistinct, simple, straight, length ca. one-half to two-thirds of spore radius. Intexinal body commonly indistinct, thin, outline ± conformable with equator. Exoexine loosely enveloping intexine; finely, intensely folded and granulate.

  • Dimensions (36 specimens). Overall equatorial diameter 57 (73) 85 µm; diameter of intexine (polar view) 43 (58) 69 µm.

  • Previous records. Mount Johnstone Formation, New South Wales (Playford and Helby 1968); Galilee Basin, Queensland, zones A–E, Upper Mississippian–Lower Permian (Jones and Truswell 1992).

  • Velamisporites cortaderensis (Césari & Limarino, 1987) Playford, 2015
    Plate 10, figures 1–4

  • Synonymy.

  • 1987 Dictyotriletes cortaderensis Césari & Limarino, p. 225, pl. 2, fig. 2.

  • 2015 Velamisporites cortaderensis (Césari & Limarino, 1987) Playford, p. 26 (cum syn.), fig. 13 D–I.

  • Remarks. Specimens encountered herein are fully compatible with those described in detail from Western Australia by Playford (2015) and illustrated by Playford and Mory (2017).

  • Dimensions (15 specimens). Overall equatorial diameter 51 (62) 78 µm; intexine diameter, in polar view, 34 (51) 60 µm.

  • Previous records. Not previously reported from the Mount Johnstone Formation, Velamisporites cortaderensis (Césari & Limarino, 1987) Playford, 2015 is well represented in coeval strata of Western Australia's Perth and Carnarvon basins (Playford 2015; Playford and Mory 2017) and in Western Gondwana with a range of Mississippian through Lower Permian.

  • Turma MONOLETES Ibrahim, 1933
    Genus Aratrisporites Leschik, 1955 emend. Playford & Dettmann, 1965

  • Type species. Aratrisporites parvispinosus Leschik, 1955 [OD].

  • Aratrisporites saharaensis Loboziak, Clayton & Owens, 1986
    Plate 11, figures 12, 13

  • Synonymy.

  • 1986 Aratrisporites saharaensis Loboziak, Clayton & Owens, p. 498–499 (cum syn.), pl. 1, figs 1–20.

  • Dimensions (three specimens in polar aspect). Overall length 56, 66, 80µm; length of intexinal body 46, 55, 62µm. Overall width 44, 62, 70µm; width of intexinal body 37, 49, 52µm.

  • Previous records. The three specimens constitute the first known occurrence of this species in the Mount Johnstone Formation, but it has recently been described from correlative Western Australian deposits (Playford 2015; Playford and Mory 2017). Prior reports – from Northern and Western Gondwana – are extensive, in successions dated within the Tournaisian–?early Serpukhovian interval (Clayton 1996; Melo and Playford 2012, p. 128).

  • Genus Laevigatosporites Ibrahim, 1933

  • Type species. Laevigatosporites vulgaris Ibrahim, 1933 [OD].

  • Laevigatosporites demutabilis sp. nov.
    Plate 10, figures 5–12

  • Diagnosis. Spores bilateral, monolete. Amb oval to elongate-elliptical; plano-convex, strongly arched distally. Laesura distinct, straight; flanked, at least in part, by narrow exinal folds; length ca. four-fifths to nine-tenths of spore length. Exine laevigate, 0.8–1.5 µm thick.

  • Dimensions In polar aspect (61 specimens), length 38 (52) 70 µm; width 21 (36) 48 µm. In equatorial aspect (33 specimens), polar axis 25 (32) 42 µm.

  • Holotype. Slide K40/33, Y61/1 (Plate 10, figure 5). Proximal aspect. Amb oval, 39 × 25 µm; laesura extending close to equator, 33 µm long, margin irregularly folded; laevigate exine 0.9 µm thick.

  • Type locality. New South Wales, Balickera excavation, sample A720; Mount Johnstone Formation.

  • Etymology. Latin, demutabilis: variable, changeable.

  • Remarks. The continuously variable amb configuration characterises this morphologically simple monolete species. It differs from the Permian species Laevigatosporites colliensis (Balme & Hennelly, 1956, p. 55–56, pl. 1, figs 1–5) Venkatachala & Kar, 1968 in being generally smaller with a more variable amb, and in its exinal folding associated with the laesura (see also Backhouse 1991, p. 282, 284, pl. XIII, figs 1–4).

  • Genus Latosporites R. Potonié & Kremp, 1954

  • Type species. Latosporites latus (Kosanke, 1950) R. Potonié & Kremp, 1954 [OD].

  • Discussion. The main distinction from Laevigatosporites Ibrahim, 1933 is that Latosporites R. Potonié & Kremp, 1954 has a circular to oval equatorial outline. Moreover, following Jansonius and Hills (1976, card 1462), the genus is applied here sensu Potonié (1966, p. 98): viz. ‘wall laevigate, but may be minutely granular or punctate'.

  • Latosporites durabilis sp. nov.
    Plate 10, figures 13–18

  • Diagnosis. Spores bilateral, monolete; plano-convex, strongly arched distally. Amb circular or almost so. Laesura distinct, simple, straight, length at least three-quarters of spore length, with or without short bifurcation at one or both ends. Exine 2–3.6 µm thick; laevigate, scabrate, or minutely granulate.

  • Dimensions (12 specimens, polar view). Length 52 (62) 78 µm, width 44 (52) 77 µm.

  • Holotype. Slide K40/32, D16 (Plate 10, figure 13). Proximoequatorial aspect. Amb near-circular, 56 × 46 µm; laesura 37 µm long, with small bifurcation at one end; exine scabrate, 2.3 µm thick.

  • Type locality. New South Wales, Balickera excavation, sample A720; Mount Johnstone Formation.

  • Etymology. Latin, durabilis: strong, durable.

  • Comparison. This species is readily distinguishable from Laevigatosporites demutabilis sp. nov. in being generally larger, thicker walled, and in having an essentially circular amb.

  • Turma HILATES Dettmann, 1963
    Genus Psomospora Playford & Helby, 1968

  • Type species. Psomospora detecta Playford & Helby, 1968 [OD; M].

  • Psomospora detecta Playford & Helby, 1968
    Plate 11, figures 1a, b–11

  • Synonymy.

  • 1968 Psomospora detecta Playford & Helby, p. 114, pl. 11, figs 8–14, text-fig. 3a–d.

  • Description. Spores radial, proximally hilate; plano-convex, strongly arched distally. Tetrahedral tetrad mark perceptible to distinct, manifested by continuous or discontinuous, narrow exinal folds of variable radial extent (reaching one-third to four-fifths of distance to equator). Exine laevigate; thickness 1.4–2.5µm as measured equatorially and distally. Very fine, close-spaced intrastriae, extending radially from hilum margin, evident proximally in well-preserved specimens. Hilum, centred at proximal pole, comprising a triangular to subtriangular area of very thin, hence fragile exine, intact (margin entire) or variously fragmented (margin commonly irregular).

  • Dimensions (44 specimens). Equatorial diameter 32 (48) 76µm; diameter of proximal polar aperture (hilum) 15 (21) 32µm.

  • Previous records. Psomospora detecta Playford & Helby, 1968 is common to the Mount Johnstone Formation and age-equivalent strata in Western Australia (Playford and Helby 1968; Playford 2015; Playford and Mory 2017). Jones and Truswell (1992) reported the species from younger Carboniferous–Early Permian strata in the Galilee Basin, Queensland. Melo and Playford (2012, p. 129) documented the extensive Late Mississippian–Middle Permian distribution of P. detecta in Western and Northern Gondwana, noting its confinement to the supercontinent. Vergel et al. (2015, table 1, fig. 4.7) reported this species from late Serpukhovian–Bashkirian strata of the Calingasta-Uspallata Basin (north-west Argentina), but their illustrated specimen is indifferently preserved such that its identity is problematic.

  • 4.2.2. Algal cysts (zygospores)

    Division CHLOROPHYTA Pascher, 1914
    Class ZYGNEMAPHYCEAE Round, 1971
    Genus Tetraporina Naumova, 1939

  • Type species. Tetraporina antiqua Naumova, 1950 [neotype; OD, Potonié, 1960, p. 130].

  • Discussion. Jansonius and Hills (1976, 1977, 1981; cards 2877, 3416, 3917–3919) systematically elaborated on the convoluted nomenclatural history of this quadrate genus, the scope and status of which still await satisfactory resolution. It was originally regarded (Naumova 1939; Bolkhovitina 1953) as a form of porate angiospermous pollen. However, numerous fossil records dating from the Mississippian onwards are distinctly aporate and are considered representative of the acid-resistant zygospores of freshwater zygnemataceous chlorophytes (e.g. Head 1992; Colbath and Grenfell 1995; van Geel and Grenfell 1996; Worobiec and Worobiec 2008).

  • Tetraporina horologia (Staplin, 1960) Playford, 1963
    Plate 11, figure 14

  • Synonymy.

  • 1960 Azonotetraporina? horologia Staplin, p. 6, pl. 1, figs 4, 6.

  • 1963 Tetraporina horologia (Staplin) Playford, p. 659, pl. 95, figs 14, 15.

  • Description. Cysts inaperturate; quadrangular (approximately square), opposing sides ± straight or concave; corners rounded, unthickened, slightly folded. Wall essentially laevigate or scabrate, 1.2–1.5 µm thick.

  • Dimensions (two specimens). Length of sides 51 × 47 µm, 55 × 49 µm.

  • Remarks. The specimen figured by del Papa and di Pasquo (2007, fig. 9J) as Tetraporina punctata (Tiwar & Navale) Kar & Bose, 1976 could be representative of T. horologia (Staplin, 1960) Playford, 1963.

  • Previous records. Following its description from nonmarine Mississippian rocks of Western Canada and Spitsbergen (Staplin 1960; Playford 1963), the species has been reported elsewhere from Mississippian and later Palaeozoic deposits (e.g. Hemer and Nygreen 1967; Cazzulo-Klepzig et al. 2002, 2005; di Pasquo 2003; Mullins and Servais 2008; Barbolini et al. 2016; Lopes et al. 2016).

  • 5. Composition of palynoflora

    The diverse, well-preserved, and wholly nonmarine palynoflora of the Mount Johnstone Formation comprises predominantly trilete spores (at least 47 species, the number of Calamospora species being undetermined), three species of monolete spores, and one species of hilate spores, together with a single species of algal cysts. Based on systematic counting of 250 specimens in two representative samples, Figure 3 depicts appreciable variation from both qualitative-taxonomic and quantitative perspectives. This accords with Playford and Helby's (1968, p. 115) statement pointing to some inconsistency in species occurrences. The most abundant species in both samples is Reticulatisporites magnidictyus, joined by similar high frequencies of Velamisporites australiensis and Rattiganispora apiculata in A707 and of Psomospora detecta and Laevigatosporites demutabilis in A720. Other species, including Indotriradites kuttungensis, Punctatisporites lucidulus, P. subtritus, Verrucosisporites quasigobbettii, Grandispora maculosa, and Raistrickia spp., are more or less consistently represented, albeit in lesser abundances, in both samples. Detailed examination of the other samples studied here show similar compositional variations. Consistently lacking throughout are any pollen grains or prepollen, a circumstance of chronostratigraphic significance, as discussed below (section 6.1).

    6. Correlation and age of palynoflora

    The distribution of the Grandispora maculosa palynoflora in Australia and elsewhere in Gondwana – particularly in Brazil and Argentina; also in North Africa/the Middle East – is discussed below, followed by a consideration of its age.

    Figure 3.

    Quantitative distribution of palynomorph species in two representative samples of the Mount Johnstone Formation. Relative abundances are based on systematic counts of 250 specimens per strew slide from each sample. Relative abundances are denoted as follows: va, very abundant (> 25% of content); a, abundant (>10–25%); c, common (>5–10%); u, uncommon (1–5%); r (< 1%); ‘x’ indicates observed presence in sample, but not in actual count-traverse.

    img-z31-1_621.jpg

    6.1. Correlation within Australia

    The clear correlation between the Mount Johnstone Formation's Grandispora maculosa Assemblage, as originally reported (Playford and Helby, 1968), and the Western Australian palynofloras from the northern Perth Basin and the Carnarvon Basin described by Playford (2015) and Playford and Mory (2017) was highlighted by the latter authors (p. 28–29 and p. 308 respectively). The current, more detailed Mount Johnstone study reinforces that correlation. The shared species in the Western Australian strata now number 26 out of the 51 recorded herein (cf. section 4.1 Taxonomic inventory and Table 1). This may seem, prima facie, not particularly persuasive from a correlative perspective. However, most of the Western Australian ‘absentees’ – such as Verrucosisporites souzai, V. iannuzzii, Convolutispora perplicata, Radiizonates arcuatus, Aratrisporites saharaensis, Rattiganispora apiculata, and Velamisporites australiensis – are only sparingly and/or very inconsistently represented in the Mount Johnstone Formation.

    Table 1.

    Compendium of miospore species identified in the Mount Johnstone Formation and their reported presence in coeval or near-coeval Mississippian strata from elsewhere in the Gondwana supercontinent. See systematic section for sources of data.

    img-z31-6_621.gif

    From the southern Galilee Basin of Queensland, the lower part of Jones and Truswell's (1992) Carboniferous–Permian palynostratigraphic sequence includes several species in common with the Mount Johnstone Formation, including Verrucosisporites quasigobbettii, Dibolisporites disfacies, and Velamisporites cortaderensis (see Playford 2015, p. 28, table 1). However, the more characteristic components of the Grandispora maculosa Assemblage are notably absent. Moreover, the presence of bilaterally symmetrical monosaccate pollen grains (prepollen) and radially symmetrical monosaccate pollen grains throughout the Galilee Basin succession (zones A–E of Jones and Truswell, 1992), but unrecorded in the Mount Johnstone Formation and its Western Australian correlatives, signifies a younger age, dating from the later Serpukhovian (Playford 2015, p. 33; and references cited therein).

    6.2. Extra-Australian correlation

    With few exceptions, the Mount Johnstone Formation and age-equivalent Western Australian strata share their appreciable cohort of diagnostic spore species with palynofloras reported from South America (Western Gondwana) and from the North African/Middle Eastern region (Northern Gondwana), as summarised in Table 1. This attests to the widespread dispersal of the Grandispora maculosa Assemblage in terrestrial and nearshore marine deposits of Gondwana during mid- to Late Mississippian time, and hence to its efficacy for long-distance chronostratigraphic correlation.

    The present study adds the following four species to the listing (Table 1; cf. Playford 2015; Playford and Mory, 2017) of trilete spores that are shared between Western and Eastern Gondwana: Verrucosisporites iannuzzii, V. souzai, Densosporites infacetus, and Radiizonates arcuatus.

    6.3. Age

    The Mount Johnstone Formation (including Italia Road Formation) was originally dated, somewhat tentatively, as Pennsylvanian (e.g. Rattigan 1967a; Playford and Helby 1968; Roberts and Engel 1987; Hamilton et al. 1974; Roberts et al. 1991). As discussed by Playford (2015) and Playford and Mory (2017), although it has not thus far been possible to date the formation directly with radiometric precision, cogent evidence in that regard has been forthcoming from sub- and suprajacent units since the mid-1990s. These data, based on K-Ar, Sensitive High-Resolution Ion Microprobe (SHRIMP), and U-Pb Refined Chemical Abrasion-Isotope Dilution Thermal Ionisation Mass Spectrometry (U-Pb CA-IDTIMS) analyses, indicate that the Mount Johnstone Formation – and, ipso facto, its northern Perth Basin and Carnarvon Basin palynologically correlative strata – are of middle to late Visean age.

    In Western and Northern Gondwana, the correlatives of the Grandispora maculosa Assemblage are similarly datable, with a possible or likely extension into the early Serpukhovian (Melo and Playford 2012, p. 148, table 1; Playford 2015, p. 33).

    7. Palaeogeographic and palaeobotanical inferences

    The palaeogeographic and palaeofloristic significance of the Grandispora maculosa Assemblage and its widespread Gondwanan distribution have been discussed recently (Playford 2015, p. 29–31, table 1, fig. 15; Playford and Mory, 2017, p. 306–308, fig. 3) and hence require no reiteration here. One especially prominent component of the assemblage – Reticulatisporites magnidictyus – was highlighted by Playford (2017) vis-à-vis its distinctive and variable morphology and its extensive, exclusively Gondwanan palaeogeographic distribution.

    In purely qualitative terms, the Mount Johnstone Formation's palynoflora consists chiefly of variously sculptured, acavate and cavate, trilete spores, associated with some simple monolete and hilate spores. Parental plant sources can be envisaged as a range of cryptogamic land plants – mostly lycopods, ferns, and articulates. Of these, lepidodendrids and ‘Rhacopteris’ (aka Pseudorhacopteris Rigby, 1973, Nothorhacopteris Archangelsky, 1983) are the main megafossils preserved in the formation (Rattigan 1967a; Roberts et al. 1991). As mentioned previously, the absence of megascopic or palynological remains of gymnosperms, such as the walchian conifers, in strata hosting the Grandispora maculosa suite is particularly noteworthy.

    8. Conclusions

    • The Mount Johnstone Formation's well-preserved palynoflora – the Grandispora maculosa Assemblage – is considerably more diverse than originally reported some five decades ago. This applies particularly to its extensive range of trilete miospores; hitherto unreported are its content of two species of monolete spores.

    • Deposition under nonmarine fluvial conditions is supported by the complete absence of marine palynomorphs.

    • Precise intra-Gondwanan correlation is further accentuated by this Eastern Gondwana study, particularly with South America. Key species in that regard are, inter alia, Reticulatisporites magnidictyus, Grandispora maculosa, Verrucosisporites quasigobbettii, Raistrickia radiosa, Cordylosporites asperidictyus, Rattiganispora apiculata, and Psomospora detecta.

    • Based on palynostratigraphic and (indirect) absolute-age determinations, the Mount Johnstone Formation is datable as middle through late Visean, certainly pre-late Serpukhovian as evidenced by the total lack of gymnospermous prepollen.

    Disclosure statement

    No potential conflict of interest was reported by the author.

    Acknowledgements

    Sincere appreciation is expressed to the following: Dr Gideon Rosenbaum and Vikram Neelesh Vakil (both of the School of Earth and Environmental Sciences, The University of Queensland) for the former's expert advice on the New England Orogen, and the latter's drafting of Figures 1 and 2; and Dra Mercedes di Pasquo (Conicet, Diamente, Entre Rios, Argentina) for helpful taxonomic advice. Dr James Riding's editorial advice and expertise are warmly acknowledged as are the helpful comments by the reviewers, Dra Silvia Césari and Dr Duncan McLean.

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    Appendices

    Appendix 1

    Inventory of specimens illustrated in Plates 1–11. Sample numbers are as cited and positioned in Figure 2. Precise locations of individual specimens on numbered slides are specified by EF coordinates secured via a standard England finder gridded slide. Specimen catalogue numbers (MMMC-5382 through MMMC-5549) are those of the permanent repository: Geological Survey of New South Wales, Palaeontological Type Collection, W.B. Clarke Geoscience Centre, 947–953 Londonderry Road, Londonderry, NSW 2753, Australia. In the left-hand column, type categories are parenthesised thus: Ho, holotype; Pa, paratype; To, topotype; Hy, hypotype.

    img-z36-4_621.gif

    Appendix 1.

    Continued.

    img-APNX_621.gif

    Appendix 1.

    Continued.

    img-Axc-_621.gif
    © 2019 AASP – The Palynological Society
    Geoffrey Playford "Palynology of the Mount Johnstone Formation (Mississippian), Southern New England Orogen, New South Wales, Australia," Palynology 44(4), 621-658, (27 October 2020). https://doi.org/10.1080/01916122.2019.1658236
    Published: 27 October 2020
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