Type species.—Hadrodontina anceps Staesche, 1964.

Remarks.—Genus Hadrodontina was established on the basis of disarticulated conodont elements, characterized by a thick base and discrete denticles, from the Lower Triassic Campiller Formation, South Tirol. After that, some researchers reconstructed multielement apparatuses of species of the genus (e.g. Perri and Andraghetti, 1987; Koike, 2016). Koike (2016) established Subfamily Hadrodontinae on the basis of the above-mentioned multielements which consists of angulate (palmate) P₁ and P₂, breviform digyrate M, alate S₀, extensiform digyrate S₁ and S₂, and bipennate S_3/4 elements. According to Koike (2016), Parapachycladina peculiaris (Zhang in Zhang and Yang, 1991) ( = Pachycladina peculiaris Zhang in Zhang and Yang, 1991) corresponds to H. aequabilis which was revised from Ellisonia aff. triassica Müller, 1956 in Koike et al. (2004).

Hadrodontina aequabilis Staesche, 1964, p. 275, figs. 43, 44; Perri, 1991, p. 36, pl. 2, fig. 2a, b.

Neospathodus bicostatus Tian et al., 1983, p. 375, pl. 86, fig. 5, pl. 87, fig. 1.

Pachycladina peculiaris Zhang in Zhang and Yang, 1991, p. 40, pl. 3, figs. 1, 2.

Parachirognathus ethingtoni Clark. Wang and Cao, 1993, p. 265, pl. 57, fig. 2.

Parapachycladina peculiaris (Zhang). Zhang, 1998, pl. 3, figs. 3–5, pl. 4, figs. 1, 7; Chen et al., 2015, fig. 23.

multielement apparatuses, Ellisonia aff. triassica Müller. Koike et al., 2004, p. 247, figs. 8.7, 8.8.

multielement apparatuses, Hadrodontina aequabilis Staesche. Koike, 2016, p. 164–167, figs. 2.1–2.3.

Material examined.—One specimen, MPC-33146, from W01-35, one specimen, MPC-33147, from E01-01, two specimens, MPC-33148, 33149, from E02-06.

Description.—Angulate elements which curve to inner side. Crescent-shape unit bears 8 to 17 discrete denticles, slightly inclined to posterior, increase in size toward middle portion. Cusp undistinguished or situated at center of element. Convex attachment surface makes up-arched basal margin. In lower view, element forms crescent; basal pit, situated halfway along length of element, covered by slightly convex mound; basal groove extending from the pit to both anterior and posterior ends.

Remarks.—Hadrodontina aequabilis was originally described from the Campiller Formation, South Tirol by Staesche (1964). The holotype, a robust angulate element with pole-like denticles inclined posteriorly, was collected from the Induan part of the formation. Neospathodus bicostatus, angulate element which was reported from South China by Tian et al. (1983), probably corresponds to the P₁ element of Hadrodontina aequabilis. Multielement apparatus of Parapachycladina peculiaris corresponds to that of Ellisonia aff. triassica of Koike et al. (2004). The latter species was revised by Koike (2016) as H. aequabilis because of common multielements. P₁ and S₂ elements of Parachirognathus ethingtoni, reported by Wang and Cao (1993), correspond to that of H. aequabilis (Koike, 2016). Koike (2016) also showed Smithian specimens that have slender angulate P₁ elements from the Triassic Taho Formation. Described specimens, collected from the middle to upper Smithian parts of the Tahogawa Member, Taho Formation, contain both robust and slender types.

Occurrence.—According to Staesche (1964) and Koike (2016), the range of Hadrodontina aequabilis starts in the middle Griesbachian (the Isarcicella isarcica Zone) and extends to the late Smithian. The species is reported from the Campiller Formation, southern Alps, Italy (Staesche, 1964; Perri, 1991), and from the Lower Triassic Beisi Formation, western Guangxi, South China as Pachycladina peculiaris (Zhang and Yang, 1991). In this study, the species occurred from the Guangxidella bransoni Subzone to the Scythogondolella milleri Subzone of the Novispathodus ex gr. waageni Zone of the Tahogawa Member, Taho Formation.

Type species.—Ozarkodina breviramulis Tatge, 1956.

Remarks.—Ozarkodina breviramulis, holotype of the genus, is a small angulate P₂ element characterized by a large and prominent medial cusp and very short upturned process (Hirschmann, 1959; Orchard, 2005). Multielements of the genus were reconstructed by two researchers. Orchard (2005), who established the subfamily Cornudininae in the family Gondolellidae, assembled the 15-element apparatus of Cornudina igoi Koike, 1996b (short segminate or segminiplanate P₁, angulate P₂, breviform digyrate S₁, small digyrate S₂, bipennate S_3/4, and breviform digyrate M elements) on the basis of disarticulated elements from South China. Koike (2016) reconstructed the multielement of Cornudina breviramulis (angulate P₁ and P₂, extensiform digyrate S₁ and S₂, bipennate S_3/4, and breviform digyrate M elements) and retained the genus Cornudina in the family Ellisonidae on the basis of disarticulated elements from the Taho Formation, Southwest Japan. In this study, I follow the new classification offered by Koike (2016).

Ozarkodina breviramulis Tatge, 1956, p. 139, pl. 5, fig. 12a, b.

Neospathodus peculiaris Sweet, 1970b. Beyers and Orchard, 1991, pl. 5, fig. 9.

Cornudina breviramulis (Tatge), Hirschmann, 1959, p. 44–46, pl. 4, figs. 3.1–3.21; Koike, 1996b, p. 118, figs. 3.1–3.21.

Cornudina breviramulis a (Tatge), Hirschmann, 1959, p. 46–47, pl. 4, fig. 4.

Cornudina breviramulis b (Tatge), Hirschmann, 1959, p. 47.

Cornudina breviramulis breviramulis (Tatge), Kozur, 1968, pl. 3, fig. 28; Trammer, 1971, pl. 1, fig. 3; Kozur and Mostler, 1972, p. 4, pl. 6, figs. 18, 19, pl. 15, fig. 23; Zawidzka, 1975, pl. 35, fig. 4.

Cornudina breviramulis minor Kozur, 1968, pl. 3, figs. 24, 27, 30; Trammer, 1971, pl. 1, fig. 2; Kozur and Mostler, 1972, p. 4, pl. 1, figs. 15–17, pl. 8, figs. 8, 11–16, 18, 19, pl. 12, fig. 6, pl. 15, figs. 19, 22, 24, 25; Zawidzka, 1975, pl. 35, fig. 6; Mirauta and Gheorghian, 1978, pl. 1, figs. 9, 20; Koike, 1982, p. 19, pl. 9, figs. 3, 5, 7; Ding, 1983, pl. 6, figs. 15, 16; Igo et al., 1988, figs. 3–10.

multielement apparatuses, Cornudina breviramulis (Tatge). Koike, 2016, p. 168–170, figs. 4.1–4.3.

Material examined.—One specimen, MPC-33150, from W01-14, one specimen, MPC-33151 from W01-27, one specimen, MPC-33152, from E01-01.

Description.—Angulate elements which are slightly curved to inner side. Crescent-shaped unit bears five laterally compressed discrete denticles which increase in size toward middle portion, reclined posteriorly. Cusp, two or three times larger than the other denticles, situated at the center of the element and strongly curved posteriorly. Basal margin is straight or slightly arched. In the lower view, element forms a crescent; basal pit surrounded by elliptical pocket; shallow furrow runs from the pit to both anterior and posterior ends.

Remarks.—Cornudina breviramulis, first described from the Lower and Upper Muschelkalk, Germany as Ozarkodina breviramulis by Tatge (1956), was continuously studied by Koike (1982, 1996b, 2016). Koike (1982, 1996b) described abundant specimens of C. breviramulis from the Lower to Upper Triassic formations of Thailand and Japan. Finally, Koike (2016) concluded that the species was a septimembrate apparatus containing 15 elements on the basis of abundant disarticulated elements from the Taho Formation.

According to Koike (2016), P₁ element of Cornudina breviramulis is quite similar to that of Ellisonia triassica, but denticles of the anterior process of C. breviramulis tend to be more in number and less discrete than in E. triassica. The strongly curved cusp is easily able to distinguish the species from E. triassica.

The Smithian specimens described here are similar in number of anterior and posterior denticles which increase in size toward the middle portion. However, Spathian to Norian (Upper Triassic) type specimens described by Koike (1996b) have more anterior denticles.

Occurrence.—Anisian (Middle Triassic) to Ladinian (Middle Triassic) of the Lower and Upper Muschelkalks, Germany (Tatge, 1956; Hirschmann, 1959; Kozur, 1968; Trammer, 1971; Kozur and Mostler, 1972; Zawidzka, 1975), Smithian of Gunong Keriang section, Malaysia (Koike, 1982), Smithian to Norian of the Taho Formation, Southwest Japan (Koike, 1996b, 2016; this study).

Type species.—Ellisonia triassica Müller, 1956.

Remarks.—Ellisonia triassica is named for S₀ elements (holotype) of the species from the Smithian Meekoceras beds, Crittenden Springs, Nevada, USA (Müller, 1956). The S and M elements of the species were reported worldwide and recognized as one of the longer ranging species of the Early Triassic. Koike et al. (2004) reported a natural assemblage of Ellisonia sp. cf. E. triassica Müller, 1956 from the Nabejiriyama section, central Japan and reconstructed a septimembrate apparatus consisting of 15 elements. Besides, Koike et al. (2004) reported multielement apparatuses of E. triassica on the basis of disarticulated elements from the borehole samples of the Taho Formation. The apparatus contains a triramous S₀ element that is similar to the holotype of E. triassica reported by Müller (1956).

multielement apparatuses, Ellisonia triassica Müller, 1956. Koike et al., 2004, p. 250, figs. 7.9, 7.10; Koike, 2016, p. 167, figs. 3.1, 3.2.

Material examined.—One specimen, MPC-33153, from W01-01.

Remarks.—The P₁ element of the species is only reported from the Taho Formation, Southwest Japan (Koike et al., 2004; Koike, 2016). According to those reports, the angulate P₁ element is generally characterized by completely discrete and straight denticles, 5–6 in number, with a large cusp 2–3 times larger than the other denticles, a straight basal margin and deep groove. Described specimen has a straight cusp twice as large as other denticles, a rectangular base with a straight basal margin, a convex pit, and an attachment surface with shallow groove. This type was illustrated by Koike et al. (2004, fig. 7.9, MPC02637). The rectangle base and smaller number of straight denticles of the specimen can serve to distinguish it from P₁ elements of Cornudina breviramulis and Hadrodontina aequabilis. In this study, I treated the described specimen as a P₁ element of E. triassica on the basis of the above-mentioned characters.

Occurrence.—Griesbachian to Smithian from worldwide localities: western USA (Müller, 1956; Mosher, 1968; Solien, 1979), South China (Duan, 1987), Southwest Japan (Koike, 1981, 2016; this study), and central Japan (Koike et al., 2004).

aff. Neospathodus peculiaris Sweet, 1970b, p. 255, pl. 5, fig. 19; Clark et al., 1979, pl. 1, fig. 18.

aff. Ellisonia? cf. peculiaris (Sweet), Igo, 2009, p. 182, fig. 152.22.

Material examined.—One specimen, MPC-33154, from W01-05.

Description.—Short and small sinistral segminate element; 0.32 mm in length; 0.29 mm in height. The cusp is the largest of four laterally compressed denticles which gradually incline to posterior; one large denticle in anterior and two smaller denticles make a reclined posterior margin. Basal margin is straight. Oval basal cavity, 0.14 mm in width, sharpened at both the anterior and posterior ends. Deep pit situated in slightly anterior side of the center of the cavity. Shallow furrow runs at anterior of element.

Remarks.—Lateral form of the small segminate element of the described specimen is very similar to the holotype of Neospathodus peculiaris ( = Ellisonia peculiaris; pl. 5, fig. 19, Sweet, 1970b), except for the expanded basal cavity of the specimen.

Occurrence.—The described specimen was recovered just below the first occurrence of Neospathodus dieneri (W01-05) in the Tahogawa Member.

Material examined.—One specimen, MPC-33155, from W01-20.

Description.—Angulate element; 0.33 mm in length; 0.32 mm in height; 0.08 mm in width. Four completely discrete and straight, finely striated denticles, of which the cusp is the largest, lie on a subrectangular base; strongly reclined to posterior. Anterior margin slanted anteriorly. Basal margin slightly arched. In lower view, lenticular basal cavity concave and slightly flanged at the middle of the element; shallow groove runs from basal pit to anterior end.

Remarks.—Discrete and straight denticles of the described specimen are similar to E. triassica, but the strongly reclined denticulation and lack of a denticle in the anteriormost part of the element differentiate it from the former species. The segminate P₁ element of E. peculiaris is distinguished from that of Ellisonia sp. 1 by the mode of denticulation and lachrymiform outline of the basal cavity.

Occurrence.—The Eurygnathodus costatus Subzone of the Novispathodus ex gr. waageni Zone of the Tahogawa Member.

Type species.—Staeschegnathus perrii Koike, 2016.

Remarks.—Genus Staeschegnathus was newly established in the family Ellisonidae on the basis of a multielement apparatus of Staeschegnathus perrii from the Taho Formation by Koike (2016). The apparatus of the species consists of angulate P₁ and P₂, triramous S₀, extensiform digyrate S₁ and S₂, bipennate S_3/4, and breviform digyrate M elements. According to Koike (2016), the morphological features of the P₂, M, and S₀-4 elements of S. perrii are similar to those of Cornudina breviramulis, and suggest a close relationship between those genera (Koike, 2016).

Neohindeodella? aff. riegeli (Mosher, 1968). Koike, 1981, pl. 1, fig. 9.

multielement apparatuses, Staeschegnathus perrii Koike, 2016, p. 170, figs. 5.1–5.4.

Material examined.—One specimen, MPC-33156, from W01-35, one specimen, MPC-33157, from W01-37, one specimen, MPC-33158, from E01-01.

Description.—Twisted crescent-shaped angulate elements with slightly larger cusp. Arched upper edge bears 11 to 12 pointed denticles which stand perpendicularly on both the anterior and posterior processes. Lower attachment surface is strongly arched and makes a triangularshaped basal margin. Basal pit situated under the cusp or anterior side of the crest of the basal margin. Basal groove runs from pit to both anterior and posterior ends.

Remarks.—P₁ element of Staeschegnathus perrii is characterized by perpendicular denticulation on a twisted crescent-like base. Form of smaller element (Figure 13.13, MPC-33158) is very similar to the holotype of Hadrodontina biserialis Staesche, 1964, except that the latter, which is a form species redescribed as a P₁ element of H. anceps Staesche, 1964, has secondary denticle rows on both the inner and outer sides. However, Koike (2016) pointed out that the multielement apparatus of S. perrii resembles Cornudina breviramulis and is phylogenetically related to C. breviramulis rather than to H. anceps.

Occurrence.—In this study, the species occurred from the Guangxidella bransoni Subzone to the Scythogondolella milleri Subzone of the Novispathodus ex gr. waageni Zone of the Tahogawa Member.

Type species.—Ctenognathus conservativa Müller, 1956.

Remarks.—Ctenognathus conservativa, holotype of the genus, is a carminate P₁ element. Genus Conservatella was established as one of the 15-element apparatuses of the Subfamily Mullerinae (Orchard, 2005). According to Orchard (2005), the apparatus consists of carminate P₁, extensiform digyrate P₂, alate S₀, breviform digyrate S₁ and S₂, bipennate S_3/4, and breviform digyrate M elements.

Ctenognathus conservativa Müller, 1956, p. 821, pl. 95, fig. 25.

Neospathodus conservativa (Müller). Buryi, 1979, p. 50, pl. 9, fig. 1.

Neospathodus conservativus (Müller). Sweet et al., 1971, pl. 1, fig. 10; Solien, 1979, p. 303, pl. 3, figs. 5, 6; Koike, 1982, p. 36, pl. 6, figs. 12–14.

Conservatella conservativa (Müller). Orchard, 2008, p. 402, figs. 8.20, 8.21; Orchard and Zonneveld, 2009, p. 778, fig. 13, parts 31–34; Maekawa and Igo, 2014, p. 191, figs. 138–140, 141.1–141.6.

multielement apparatuses, Conservatella aff. conservativa (Müller). Orchard, 2005, p. 81, text-fig. 7A.

Material examined.—Three specimens, MPC-33159–33161, from E01-01.

Remarks.—Carminate P₁ element of Conservatella conservativa is characterized by a rectangular base with laterally compressed denticles and slightly undulated anterior and upturned posterior basal margins. P₁ element of C. aff. conservativa of Orchard (2005) corresponds to a variant of C. conservativa reported by Maekawa and Igo (2014) from northeastern Vietnam (e.g. MPC25073, 25077 in fig. 139, and MPC25080, 25081 in fig. 140). Those elements are characterized by more discrete erect denticles on a biangular basal margin.

Collected P₁ elements show blade-like form with upturned posterior basal margin, discrete denticles and a narrow triangular-shaped basal cavity. Fine preserved element, MPC-33161, shows biangular basal margin which is similar to a variant of Conservatella conservativa. Undistinguished cusp of Japanese specimens differs from P₁ element of Discretella discreta.

Occurrence.—This species occurs from the middle Smithian of Nevada (Meekoceras beds, Müller, 1956; Sweet et al., 1971), Utah (the Furnishius Zone to the Parachirognathus Zone, Solien, 1979), South Primorye, Russia (the Parachirognathus-Furnishius Zone, Buryi, 1979), Jabra Safra, Oman (Orchard, 2005), Canadian Arctic (the Euflemingites romunderi Zone, Orchard, 2008), northeastern Vietnam (the Flemingites rursiradiatus beds to the Owenites koeneni beds within the Novispathodus ex gr. waageni Zone, Shigeta et al., 2014 and Komatsu et al., 2016), and Southwest Japan (the Guangxidella bransoni Subzone of the Novispathodus ex gr. waageni Zone, this study). Orchard and Zonneveld (2009) reported this species from the middle to upper Smithian in British Columbia, Canada (the Scythogondolella lachrymiformis Zone to the S. mosheri Zone).

Type species.—Ctenognathus discreta Müller, 1956.

Remarks.—The multielement apparatus of genus Discretella, reported by Orchard (2005), is characterized by elements with discrete, widely spaced, peg-like denticles. The apparatus is very similar to that of genus Guangxidella reported by Zhang and Yang (1991) (Orchard, 2005).

Ctenognathus discreta Müller, 1956, p. 821, pl. 95, fig. 28.

Neospathodus discretus (Müller). Tian et al., 1983, p. 376, pl. 95, fig. 1.

Neospathodus aff. cristagalli (Huckriede, 1958). Bui, 1989, p. 404, pl. 30, fig. 1.

Discretella discreta (Müller). Orchard, 2008, p. 402, figs. 8.18, 8.19; Orchard and Zonneveld, 2009, p. 778, fig. 13, parts 35, 36, 45, 46; Beranek et al., 2010, figs. 6.18, 6.19; Maekawa and Igo, 2014, p. 196, figs. 141.13–141.33, 142–145, 146.1–146.30; Chen et al., 2015, figs. 7.24–7.27; Maekawa et al., 2016, p. 197, fig. 5.1.

multielement apparatuses, Discretella sp. A, Orchard, 2005, p. 83, textfig. 8A.

Material examined.—One specimen, MPC-33162, from E01-10.

Description.—Slender segminate element length to height ratio 1.5. Rectangular unit bears five completely discrete and erect denticles of which the cusp lies at posterior end. Straight basal margin gradually upturned anteriorly; upturned beneath the cusp. Obliquely flanged basal cavity has a basal pit which is starting point of anterior groove.

Remarks.—Ctenognathus discreta, holotype of Discretella discreta, is characterized by narrow base with almost all discrete denticles, distinct larger cusp, and upturned posterior basal margin. Maekawa and Igo (2014) recognized two morphotypes (A and B) in the species on the basis of abundant specimens from the Bac Thuy Formation, northeastern Vietnam. D. discreta Morphotype A is corresponds to the holotype of the species, and D. discreta Morphotype B is characterized by triangular larger denticles and upturned posterior basal margin. Described specimen corresponds to D. discreta Morphotype B, whereas the P₁ element of Discretella sp. A of Orchard (2005) is a probable variant of the morphotype. Neospathodus aff. cristagalli reported by Bui (1989) from the formation is synonymized by Maekawa and Igo (2014).

Occurrence.—This species occurs from the middle Smithian of Nevada (Meekoceras beds, Müller, 1956), Gunong Keriang, West Malaysia (Koike, 1982), Tibet (Tian et al., 1983), Jabal Safra, Oman (Orchard, 2005), British Columbia, Canada (Orchard and Zonneveld, 2009; Beranek et al., 2010), Canadian Arctic (the Euflemingtes romunderi Zone, Orchard, 2008), the Bac Thuy Formation, northeastern Vietnam (the Flemingites rursiradiatus beds to the Owenites koeneni beds within the Novispathodus ex gr. waageni Zone, Shigeta et al., 2014 and Komatsu et al., 2016), and the Taho Formation, Southwest Japan (the Neospathodus dieneri-Ns. conservativus Zone, Koike, 1979, 1981; the Guangxidella bransoni Subzone of the Nv. ex gr. waageni Zone, this study).

?Ctenognathus discreta Müller, 1956, p. 821, pl. 95, fig. 24.

Cratognathodus robustus Wang and Wang, 1976, p. 397, pl. 3, figs. 21–25; Tian et al., 1983, p. 347, pl. 88, figs. 8, 9.

Neospathodus discreta (Müller, 1956). Buryi, 1979, p. 52, pl. 7, figs. 2–6.

Guangxidella? robustus (Wang and Wang). Orchard, 2007a, fig. 1.

Discretella robustus (Wang and Wang). Maekawa and Igo, 2014, p. 202, fig. 146.31–146.33, 147–150.

Material examined.—One specimen, MPC-33163, from W01-35, one specimen, MPC-33164, from E02-03.

Description.—Two segminate elements. Crescent-like unit bears triangular-shape denticles which increase in size posteriorly. Smaller specimen (Figure 14.6, MPC-33164) shows a large cusp two times larger than the other denticles. One or two smaller denticles follow the cusp. Basal margin up-arched. Subrounded basal cavity elongate posteriorly and concave with a narrow pit. A groove runs from the pit to the anterior end.

Remarks.—Cratognathus robustus, the holotype of Discretella robusta reported by Wang and Wang (1976), is a segminate P₁ element with a strongly reclined large cusp and exhibits a sigmoidal form in lower view. Maekawa and Igo (2014) showed abundant specimens of Discretella discreta and D. robusta from the Bac Thuy Formation, northeastern Vietnam. The described specimens closely resemble some specimens of D. robusta reported by Maekawa and Igo (2014). Some specimens of D. discreta from Vietnam exhibit a sigmoidal form in lower view (e.g. MPC25132, fig. 145.16–145.18; MPC25141, fig. 146.25–146.27). I interpret these as probably transitional forms from D. discreta to D. robusta, and therefore assign both species to genus Discretella.

Occurrence.—This species occurs from the middle Smithian of Nevada (Meekoceras beds, Müller, 1956), Qomolangma, Tibet (Wang and Wang, 1976; Tian et al., 1983), South Primorye, Russia (the Parachirognathus-Furnishius Zone, Buryi, 1979), northeastern Vietnam (the Flemingites rursiradiatus beds to the Owenites koeneni beds within the Novispathodus ex gr. waageni Zone, Shigeta et al., 2014), and Southwest Japan (the Guangxidella bransoni Subzone of the Nv. ex gr. waageni Zone, this study).

Type species.—Neoprioniodus bransoni Müller, 1956.

Remarks.—Genus Guangxidella was newly named for a seximembrate apparatus by Zhang and Yang (1991) on the basis of disarticulated elements from western Guangxi, South China. Neosprioniodus bransoni Müller (1956), type species of the genus, corresponds to the P₁ element of Guangxidella typica, which is the new name for the above-mentioned apparatus. Orchard (2005) reconstructed the apparatus of Zhang and Yang (1991) and classified the genus in the subfamily Mullerinae.

Neoprioniodus bransoni Müller, 1956, p. 829, pl. 95, figs. 19–21.

Neoprioniodus bicuspidatus Müller, 1956, p. 828, pl. 95, figs. 16, 17.

Neospathodus bicuspidatus (Müller). Solien, 1979, p. 302, pl. 3, figs. 2, 3.

Ozarkodina gigantea Bui, 1989, p. 409, pl. 31, figs. 10, 14.

Guangxidella bransoni (Müller). Maekawa and Igo, 2014, p. 211, figs. 152.16–152.18, 153–159, 160.1–160.4.

multielement apparatuses, Guangxidella typica Zhang and Yang, 1991, p. 33, pl. 1, figs. 1a, b, 2a, b.

Material examined.—One specimen, MPC-33165, from W01-35, one specimen, MPC-33166, from W01-37, two specimens, MPC-33167, 33168, from E01-01.

Remarks.—Incomplete elements from the Tahogawa Member, Taho Formation showing discrete denticles, uparched basal margin, cordiform basal cavity, and large cusp at the posterior end. Those features correspond to the holotype of Guangxidella bransoni described from the Meekoceras beds at Crittenden Springs, Nevada by Müller (1956).

Occurrence.—This species occurs from the middle Smithian of Crittenden Springs, Nevada (Meekoceras beds, Müller, 1956), the Luolou Formation, Guangxi, China (the Neospathodus waageni Zone, Zhang and Yang, 1991), the Thaynes Formation, Utah (the Parachirognathus Zone, Solien, 1979), British Columbia, Canada (Orchard and Zonneveld, 2009), the Bac Thuy Formation, northeastern Vietnam (the Urdyceras tulongensis beds and the Owenites koeneni beds within the Novispathodus ex gr. waageni Zone, Shigeta et al., 2014) and the Taho Formation, Southwest Japan (the Guangxidella bransoni Subzone of the Novispathodus ex gr. waageni Zone, this study).

Type species.—Spathognathodus cristagalli Huckriede, 1958.

Remarks.—Genus Neospathodus was established for a Triassic segminate P₁ element which was characterized by a terminal or nearly terminal basal cavity by Mosher (1968). The seximembrate apparatus of Neospathodus cf. cristagalli was reconstructed by Orchard (2005). The elements of this apparatus show a smaller number of denticles compared with Novispathodus.

Neospathodus concavus Zhao and Orchard in Zhao et al., 2007, p. 35, pl. 1, fig. 1A–C; Orchard and Krystyn, 2007, fig. 4; Igo, 2009, p. 184, fig. 154.13.

Neospathodus cf. concavus Zhao and Orchard. Maekawa et al., 2016, p. 199, fig. 4.12.

Material examined.—Two specimens, MPC-33171, 33172, from W01-13, one specimen, MPC-33173, from W01-14, two specimens, MPC-33174, 33175, from W01-17.

Description.—Bowed segminate element. Denticles with a pointed tip, 7 to 12 in number, progressively reclined posterior. Large cusp situated at posterior end. Up-arched anterior basal margin with upturned or downturned posterior margin beneath the basal cavity. Anterior end of element slanted. Rounded basal cavity has a slightly concave pit; a groove runs from pit to anterior end.

Remarks.—Neospathodus sp. 2 from the Taho Formation differs from this species in its weaker bowed unit and fine denticulation.

Occurrence.—This species occurs from the upper Dienerian to lower Smithian of the Mikin Formation, Mud Section, Spiti, India (the Neospathodus cristagalli Zone within the Gyronites frequens Zone, Orchard and Krystyn, 2007), the West Pingdingshan section, Anhui Province, South China (the Ns. waageni eowaageni Subzone to the Ns. waageni waageni Subzone with the Flemingites-Euflemingites Zone, Zhao et al., 2007), the Bac Thuy Formation, northeastern Vietnam (Maekawa et al., 2016), and the Taho Formation, Southwest Japan (the Novispathodus ex gr. waageni Zone, this study).

Spathognathodus cristagalli Huckriede, 1958, p. 161, pl. 10, fig. 14, 15.

Neospathodus cristagalli (Huckriede). Sweet, 1970a, p. 9, pl. 1, figs. 18, 21; Sweet, 1970b, p. 246, pl. 1, figs. 14, 15; Mosher, 1973, p. 170, pl. 20, fig. 4; Matsuda, 1982, p. 92, pl. 3, figs. 1–12; Tian et al., 1983, p. 375, pl. 80, fig. 2a, b; Orchard and Krystyn, 2007, pl. 1, fig. 5; Orchard and Zonneveld, 2009, p. 782, fig. 14, parts 14, 15, 20; Maekawa and Igo, 2014, p. 223, figs. 161.10–161.12; Maekawa et al., 2015, p. 315, figs. 5.4–5.6.

multielement apparatuses, Neospathodus cf. cristagalli (Huckriede). Orchard, 2005, p. 88, text-fig. 14A.

Material examined.—Two specimens, MPC-33176, 33177, from W01-10, three specimens, MPC-33181–33183, from W01-12, two specimens, MPC-33190, 33191, from W01-13, one specimen, MPC-33195, from W01-16, four specimens, MPC-33199–33202, from W01-22, three specimens, MPC-33205–33207, from W01-27.

Description.—Laterally compressed blade-like element. Arched upper edge bears slightly fused and reclined denticles, 7 to 13 in number, with a pointed tip. Triangular-shaped denticle situated at posterior end. Straight basal margin turned upward beneath the basal cavity. Oval or lozenge-shaped basal cavity surrounding a basal pit, and the posterior margin of basal cavity of larger elements elongated. A groove runs from the pit to the anterior end.

Remarks.—Both Novispathodus ex gr. waageni and Ns. dieneri differ from the species by their rounded basal cavity and different denticle profiles.

Occurrence.—The species range is from the upper Dienerian to Smithian and it has been reported from the Salt Range, Pakistan (Huckriede, 1958; Sweet, 1970a, b), British Columbia, Canada (the Vavilovites sverdrupi Zone, Mosher, 1973; the Scythogondolella lachrymiformis Zone to the Paullella meeki Zone, Orchard and Zonneveld, 2009), Kashmir, India (Matsuda, 1982), Tibet (Tian et al., 1983), Mud Section, Spiti, India (the Neospathodus cristagalli Zone to the Neospathodus waageni sensu stricto Zone with the Gyronites frequens Zone, the Meekophiceras? vercherei beds and the Rohillites rohilla Zone, Krystyn et al., 2007; Orchard, 2007b; Orchard and Krystyn, 2007; Orchard, 2010), northeastern Vietnam (Maekawa et al., 2015; the Flemingites rursiradiatus beds within the Novispathodus ex gr. waageni Zone, Shigeta et al., 2014), and Southwest Japan (the Neospathodus cristagalli Zone to the Eurygnathodus costatus Subzone of the Novispathodus ex gr. waageni Zone, this study).

Neospathodus dieneri Sweet, 1970a, p. 9, pl. 1, fig. 17; Sweet, 1970b, p. 249, pl. 1, figs. 1, 4; McTavish, 1973, p. 293, pl. 2, figs. 3, 6; Birkenmajer and Trammer, 1975, pl. 1, fig. 4; Buryi, 1979, p. 52, pl. 7, fig. 7; Wang and Cao, 1981, pl. 2, figs. 24, 25; Matsuda, 1982, p. 90, pl. 2, figs. 1–11; Koike, 1982, p. 37, pl. 6, figs. 15–21, 25; Dagis, 1984, pl. 6, figs. 4–7; Beyers and Orchard, 1991, pl. 5, fig. 4; Wang and Zhong, 1994, p. 400, pl. 1, fig. 18; Zhao and Orchard in Zhao et al., 2007, p. 35, pl. 1, fig. 9A– C, 11A–C ,12A, B; Orchard and Krystyn, 2007, figs. 3, 6, 7; Igo, 2009, p. 186, figs. 151.6–151.16, 152.8, 152.9; Orchard and Zonneveld, 2009, p. 782, fig. 14, parts 1–4; Beranek et al., 2010, figs. 6.20, 6.21; Maekawa and Igo, 2014, p. 224, figs. 161.13–161.45, 162, 163, 164.1–164.6; Chen et al., 2015, fig. 9.18; Maekawa et al., 2016, p. 199, 200, figs. 4.8–4.10.

Material examined.—One specimen, MPC-33208, from W01-06, three specimens, MPC-33209–33211, from W01-10, three specimens, MPC-33212–33214, from W01-11, two specimens, MPC-33218, 33219, from W01-12, nine specimens, MPC-33222–33230, from W01-13, three specimens, MPC-33240–33242, from W01-14, one specimen, MPC-33245, from W01-32, two specimens, MPC-33246, 33247, from W01-44, one specimen, MPC-33248, from E01-01, one specimen, MPC-33249, from E01-12, one specimen, MPC-33250, from E02-03, one specimen, MPC-33251, from E03-03.

Description.—Subtriangular segminate element. Denticles with pointed tip, 3 to 9 in number, erect or gradually reclined posteriorly. The slightly to distinctively larger, high cusp is situated terminally or in posterior one-third of element. Denticles progressively increase in size toward cusp. Straight or slightly upturned basal margin upturned beneath basal cavity. Rounded or subrounded basal cavity with rounded posterior margin. A groove runs from basal pit to anterior end.

Remarks.—Zhao et al. (2007) divided Neospathodus dieneri into three morphotypes on the basis of differences in the configuration of the cusp and penultimate denticle of the P₁ element. According to Zhao et al. (2007), these morphotypes appear successively from the base of the Dienerian and continue to the Smithian of the Yinkeng Formation in the West Pingdingshan Section, South China. In this study, specimens of Ns. dieneri contain the three morphotypes of Zhao et al. (2007), and Morphotype 2, which has a penultimate denticle of equal size to the cusp, appeared at the lowest level of the surface outcrop in the western part of the stratotype area of the Taho Formation. The range of Ns. dieneri Morphotype 1 generally starts with Sweetospathodus kummeli in the lower Dienerian, but in this study area, Ns. dieneri Morphotype 1 and 3 occurred about 2 m above the FO of Morphotype 2 (loc. W01-10). The absence of S. kummeli there indicates the FO of Morphotype 2 corresponds to the upper Dienerian. Koike (1996a) reported the FADs of S. kummeli and Ns. dieneri from the level of 17.60 m beneath the ground surface of the eastern part of the area. Thus, in the western part, the FO of Ns. dieneri Morphotype 1 is beneath the ground surface.

In the Tahogawa Member, Taho Formation, the range of Ns. dieneri Morphotype 1 and 2 extends to the upper part of the Novispathodus ex gr. waageni Zone, but that of Ns. dieneri Morphotype 3 was limited to beneath the FO of Eurygnathodus costatus.

Occurrence.—This species ranges from the Dienerian to Smithian of the Salt Range, West Pakistan (Zone 3 to middle part of Zone 7, Sweet, 1970a, b), Australia (McTavish, 1973), Svalbard (Birkenmajer and Trammer, 1975; Hatleberg and Clark, 1984), Spiti, India (Goel, 1977; Orchard and Krystyn, 2007), South Primorye, Russia (the Neospathodus dieneri-Ns. pakistanensis Zone with the Clypeoceras spitiense “bed” and the lower part of the Paranorites varians Zone, Shigeta et al., 2009), South China (Wang and Cao, 1981; the Neospathodus dieneri M1 Zone to the lower part of the Ns. waageni waageni Subzone with the upper part of the Ophiceras-Lytophiceras Zone, the Prionolobus-Gyronites Zone and the lower part of the Flemingites-Euflemingites Zone, Zhao et al., 2007), Kashmir, India (Matsuda, 1982), Malaysia (Koike, 1982), British Columbia, Canada (Beyers and Orchard, 1991; Beranek et al., 2010), northeastern Vietnam (Maekawa et al., 2016; the Flemingites rursiradiatus beds to the Owenites koeneni beds within the Novispathodus ex gr. waageni Zone, Shigeta et al., 2014), and Southwest Japan (the Ns. dieneri Zone to the Nv. ex gr. waageni Zone, this study).

Neospathodus novaehollandiae McTavish, 1973, p. 294, figs. 4, 5, 14, 16–23; Goel, 1977, p. 1091, pl. 1, figs. 1, 2; Beyers and Orchard, 1991, pl. 5, fig. 7; Orchard, 2007b, figs. 15–18, 27, 28; Igo, 2009, p. 188, figs. 153.8–153.14, 154.7–154.11, 155.1–155.11; Maekawa and Igo, 2014, p. 228, figs. 164.7–164.24, 165.1–165.3.

Material examined.—Two specimens, MPC-33252, 33253, from W01-16, one specimen, MPC-33254, from W01-21, one specimen, MPC-33255, from W01-22, two specimens, MPC-33256, 33257, from W01-33.

Description.—Large blade-like elements. Arched upper edge bears robust, broad, and fused denticles on a rectangular unit; denticles vary in number from 10 to 13; suberect anteriorly and gradually reclined posteriorly. Height of the denticles gradually increases to near the posterior end, and then decreases in the posterior one-third. Prominent lateral rib makes cap on basal cavity. Straight basal margin slightly upturned beneath basal cavity which shows expanded oval with elongated posterior end. Deep furrow runs from basal pit to anterior end.

Remarks.—The P₁ element of Neospathodus novaehollandiae is distinguished from that of Ns. pakistanensis by moderately thick basal cap and lateral flange (Orchard, 2007b). The described specimens bear the important character.

Occurrence.—This species occurs from the Smithian of West Australia (McTavish, 1973), Spiti, India (Goel, 1977; Orchard, 2007b), British Columbia, Canada (Beyers and Orchard, 1991), South Primorye, Russia (the Neospathodus ex gr. waageni-Ns. novaehollandiae Zone with the Clypeoceras timorense Zone and the Radioprionites abrekensis “bed”, Shigeta et al., 2009), northeastern Vietnam (the Flemingites rursiradiatus and the Urdyceras tulongensis beds within the Novispathodus ex gr. waageni Zone, Shigeta et al., 2014), and Southwest Japan (the Novispathodus ex gr. waageni Zone, this study).

Neospathodus pakistanensis Sweet, 1970b, p. 254, pl. 1, figs. 16, 17; McTavish, 1973, p. 295, pl. 1, figs. 1, 2; Buryi, 1979, p. 57, pl. 9. fig. 2; Wang and Cao, 1981, p. 367, pl. 2, fig. 27; Matsuda, 1983, p. 87, pl. 1, figs. 1–5; Tian et al., 1983, p. 379, pl. 81, fig. 3; Dagis, 1984, p. 26, pl. 5, figs. 9–11; Hatleberg and Clark, 1984, pl. 1, fig. 5; Beyers and Orchard, 1991, pl. 5, fig. 2; Cao and Wang, 1993, pl. 56, fig. 14; Orchard, 2007b, figs. 19, 20, 23–26; Orchard and Krystyn, 2007, figs. 19, 20; Orchard, 2008, p. 407, figs. 8.11, 8.12; Igo, 2009, p. 190, figs. 151.18–151.26, 152.1–152.7, 152.10–152.13, 152.20–152.21, 153.1–153.7, 154.1–154.6; Orchard and Zonneveld, 2009, p. 784, fig. 13, parts 18–21, 25, 26; Beranek et al., 2010, figs. 6.31–6.33; Maekawa and Igo, 2014, p. 228, figs. 165.4–165.24; Maekawa et al., 2015, p. 315, fig. 5.3.

Neospathodus homeri (Bender). Bui, 1989, p. 402, pl. 31, fig. 16.

Material examined.—Four specimens, MPC-33259–33262, from W01-13, one specimen, MPC-33263, from W01-16, four specimens, MPC-33264–33267, from W01-20, one specimen, MPC-33268, from W01-21, one specimens, MPC-33269, from W01-30.

Description.—Blade-like elements. Rectangular unit bears denticles with pointed tip, 8 to 12 in number, reclined posteriorly. Some specimens have a developed lateral rib and one to three posterior denticles, progressively smaller to the posterior of the highest point. Straight or slightly up-arched basal margin forms distinctive crest beneath the center of subrounded basal cavity which is elongated antero-posteriorly. A groove runs from basal pit to anterior end.

Remarks.—Neospathodus pakistanensis was first described by Sweet (1970b) from the Salt Range, West Pakistan. The form of the P₁ element of the species is similar to Ns. novaehollandiae. McTavish (1973) treated the species as the offspring of the Ns. pakistanensis lineage. Orchard (2007b) suggested the two species were conspecific. In this study, I recognized Ns. pakistanensis by its downturned posterior lower margin, and Ns. novaehollandiae by strong lateral ribs. These species differ from Ns. posterolongatus, which has an elongate basal cavity.

Occurrence.—This species was already reported from the upper Dienerian to lower Smithian strata in the Salt Range, Pakistan (Zone 6, Sweet, 1970b), West Australia (McTavish, 1973), South Primorye (Buryi, 1979; the Neospathodus dieneri-Ns. pakistanensis Zone and the Neospathodus ex gr. waageni-Ns. novaehollandiae Zone with the Clypeoceras spitiense “bed”, the Paranorites varians Zone and the Clypeoceras timorense Zone, Shigeta et al., 2009), South China (Wang and Cao and Wang, 1993; Ji et al., 2011; Goudemand, 2014), Kashmir, India (Matsuda, 1983), Tibet (Tian et al., 1983), Spiti, India (Krystyn et al., 2007; Orchard, 2007b; Orchard and Krystyn, 2007; Goudemand, 2014), British Columbia, Canada (the Scythogondolella lachrymiformis Zone to Paullella meeki Zone, Orchard and Zonneveld, 2009), northeastern Vietnam (Maekawa et al., 2015; the Flemingtes rursiradiatus beds within the Novispathodus ex gr. waageni Zone, Shigeta et al., 2014), and Southwest Japan (the Novispathodus ex gr. waageni Zone, this study).

Goudemand (2014) recovered Novispathodus waageni new subspecies A from bed 10 in Mud section, Spiti, India which is slightly below the FAD of Neospathodus pakistanensis. In this study, the FO of Ns. pakistanensis is similar to that of Nv. ex gr. waageni. On the basis of those two data, the range of Ns. pakistanensis probably starts in the earliest Smithian.

Neospathodus waageni subsp. B Zhao et al., 2004, p. 42, fig. 2.

Neospathodus posterolongatus Zhao and Orchard in Zhao et al., 2007, p. 36, pl. 1, fig. 2A–C; Orchard, 2007b, figs. 1–6; Orchard, 2008, p. 407, figs. 8.3, 8.4; Orchard and Zonneveld, 2009, p. 784, fig. 14, parts 7, 8, 16, 17, 21, 22; Beranek et al., 2010, figs. 6.24, 6.25; Maekawa and Igo, 2014, p. 230, figs. 165.25–165.33, 166.1–166.18.

Material examined.—Two specimens, MPC-33271, 33272, from W01-21, two specimens, MPC-33273, 33274, from W01-22, one specimen, MPC-33275, from W01-24, one specimen, MPC-33276, from W01-30.

Description.—Blade-like elements. Arched upper edge bears denticles that vary in number from 11 to 14; discrete in upper half; increasingly reclined posteriorly; denticle size decreases to both anterior and posterior ends. Highest point situated in posterior one-third. Straight lower edge upturned beneath basal cavity. Subrounded basal cavity elongated and pointed posteriorly, and occupying one-third of basal margin. A groove runs from basal pit to anterior end.

Remarks.—Ns. posterolongatus is distinguishable from Novispathodus waageni by the posterior elongation of the basal cavity (Zhao et al., 2007).

Occurrence.—Neospathodus posterolongatus is mainly reported from two candidate sections of GSSP of the Induan-Olenekian Boundary (IOB) in the Yinkeng Formation at the West Pingdingshan section, South China (Zhao et al., 2007, 2008b) and the Mianwali Formation, Spiti, India (Krystyn et al., 2007; Orchard and Krystyn, 2007). Goudemand (2014) reinvestigated the two candidate sections of the IOB and reported that the FAD of Novispathodus ex gr. waageni is lower than that of Ns. posterolongatus sensu stricto. Thus, the range of the species starts in the early Smithian. Japanese data follow the species range.

This species has also been reported from the Smithian of the Canadian Arctic (the Euflemingites romunderi Zone, Orchard, 2008), British Columbia, Canada (the Scythogondolella lachrymiformis Zone to the Scythogondolella phryna Subzone of the S. mosheri Zone, Orchard and Zonneveld, 2009; Beranek et al., 2010), northeastern Vietnam (the Flemingites rursiradiatus beds within the Nv. ex gr. waageni Zone, Shigeta et al., 2014), and Southwest Japan (the Eurygnathodus costatus Subzone of the Nv. ex gr. waageni Zone, this study).

Neospathodus robustus Koike, 1982, p. 39, pl. VI, figs. 32–35.

Neospathodus cyclodontus Zhao and Orchard in Zhao et al., 2008a, p. 211, fig. 8a–c.

Material examined.—Two specimens, MPC-33280, 33281, from W01-13, one specimen, MPC-33282, from W01-14, one specimen, MPC-33283, from W01-16, two specimens, MPC-33284, 33285, from W01-17.

Description.—Robust segminate element, subtriangular in both upper and lateral views. Discrete denticles of smaller specimens are progressively fused with growth. Robust fused denticles reclined posteriorly. Anterior basal margin slightly up-arched or straight and upturned beneath basal cavity. Subrounded or oval expanded basal cavity slightly concave and has basal pit. The basal cup is thickened and continues as an anterior flange. Deep groove runs from the pit to the anterior end.

Remarks.—Neospathodus robustus was originally described from the limestone section in Gunong Keriang region, West Malaysia by Koike (1982). The robust element of Neospathodus cyclodontus Zhao and Orchard in Zhao et al., 2008a is very similar to that of Ns. robustus. Especially, robust discrete denticles, upturned oval basal cavity and a moderately thickened middle portion are common in the two species. In this study, I treat the latter species as a synonym of the former. Neospathodus concavus is distinguished from Ns. robustus by its clearly arched unit, rounded basal cavity and slender unit.

Almost all P₁ elements of Neospathodus robustus reported by Chen et al. (2016) from Slovenia show a subtriangular basal cavity and were recovered from Spathian strata. Those elements are excluded from the present species.

Occurrence.—This species occurs from the Smithian limestone section in Gunong Keriang region, West Malaysia (Koike, 1982), the Yinkeng Formation, West Pingdingshan section, South China (the Gyronites-Prionolobus Zone, Zhao et al., 2008a, b), and Southwest Japan (the Novispathodus ex gr. waageni Zone, this study). According to those reports, the range of the species is limited to the lower Smithian and the distribution is restricted from eastern Tethys to western Panthalassa.

Material examined.—One specimen, MPC-33286, from W01-12, one specimen, MPC-33288, from W01-13.

Description.—Segminate elements. Upper edge gets gradually higher posteriorly and bears 9 denticles; progressively reclined posteriorly; highest point situated near posterior end. Both anterior and posterior basal margin upturned. Posterior margin shows a crescent shape. Slightly expanded and rounded basal cavity has shallow basal pit. A groove runs from the pit to the anterior end.

Remarks.—Progressively reclined denticles and crescent-shaped posterior lateral margin of Neospathodus sp. 1 distinguish it from other species of Neospathodus. Neospathodus dieneri resembles the smaller specimen of the present species but can be distinguished by the smaller number of denticles and erect denticulation. The species differs from Ns. cristagalli by lacking a terminal triangular cusp, and by having a more rounded basal cavity.

Occurrence.—The species occurs from the Ns. cristagalli Zone to the Nv. ex gr. waageni Zone of the Tahogawa Member (this study).

Material examined.—Two specimens, MPC-33291, 33292, from W01-13.

Description.—Segminate elements. Slender rectangular unit bears 8 or 12 discrete denticles which strongly recline posteriorly. Cusp undistinguished and highest position situated near posterior end. Basal margin straight and downturned beneath basal cavity. Oval basal cavity has basal pit. A groove runs from the pit to the anterior end.

Remarks.—The height of the described species is lower than the P₁ elements of Neospathodus dieneri and Ns. cristagalli. The species is distinguished from Ns. pakistanensis by its strongly reclined discrete denticles.

Occurrence.—The species occurs from the Novispathodus ex gr. waageni Zone of the Tahogawa Member (this study).

Type specimens.—Holotype, MPC-33293, from W01-13; paratypes, seven specimens, MPC-33294–33300, from W01-13.

Etymology.—Latin, arcus, arch: for up-arched anterior part of the P₁ element of the species.

Diagnosis.—Subtriangular segminate P₁ element with an arcuate lower anterior basal margin, an upturned posterior basal margin, bearing increasingly reclined and discrete subtriangular, laterally compressed denticles that increase in size and length posteriorly. A variably developed cusp is situated above a large, rounded or subrounded basal cavity with one or two posterior denticles.

Description.—Eight subtriangular segminate elements 0.32–0.69 mm, average 0.52 in length; 0.25–0.60 mm, average 0.40 in height; length to height ratio 1.2–1.5, average 1.3. Slender rectangular unit bears subtriangular discrete denticles that vary in number from 6 to 9, average 7; laterally compressed; erect anteriorly and gradually reclined posteriorly. Undistinguished cusp, except in one paratype (Figure 17.16, MPC-33297). Anterior basal margin up-arched with upturned posterior basal margin. Rounded or subrounded basal cavity strongly expanded in some specimens and holotype. A groove runs from basal pit to anterior end.

Remarks.—Lateral profile and mode of denticulation of Neospathodus arcus closely resemble that of Ns. dieneri, but distinctively discrete denticles and up-arched anterior basal margin differentiate it from the latter. The laterally compressed subtriangular denticulation of the species differs from that of Ns. concavus. One paratype specimen, MPC-33297, has a distinct cusp which probably consists of two fused denticles. It is an intraspecific variant of the species.

Occurrence.—The species occurs from the Neospathodus cristagalli and the lowest part of the Novispathodus ex gr. waageni zones of the Tahogawa Member (this study).

Type species.—Novispathodus abruptus (Orchard, 1995).

Remarks.—Genus Novispathodus was established as a 15-element apparatus belonging to subfamily Novispathodinae (Orchard, 2005). Novispathodus abruptus, type species of the genus, is a segminate P₁ element which was recovered from Jabal Safra, Oman by Orchard (1995). The genus Triassospathodus probably evolved from the Novispathodus lineage, which has a different apparatus, including a segminate-like angulate P₂, weakly digyrate S₂ and anterior downturned S_3/4 elements.

Neospathodus homeri (Bender). Koike, 1981, pl. 1, fig. 5.

Neospathodus abruptus Orchard, 1995, p. 118, 119, figs. 3.16–3.19, 3.23–3.2; Lucas and Orchard, 2007, figs. 7.10–7.12.

Novispathodus abruptus (Orchard). Lucas and Orchard, 2007, figs. 7.10–7.12; Orchard and Zonneveld, 2009, p. 784, fig. 15, parts 34–37; Chen et al., 2015, figs. 7.14, 7.18, 8.2, 9.13, 9.16, 9.17.

Novispathodus ex gr. abruptus (Orchard). Komatsu et al., 2016, p. 72, figs. 5.6, 5.7.

Triassospathodus homeri (Bender). Maekawa and Igo, 2014, p. 253, figs. 181.43–181.48; Chen et al., 2015, figs. 7.13, 9.14, 9.19.

Triassospathodus symmetricus (Orchard). Maekawa and Igo, 2014, p. 254, figs. 182–185, 186.1–186.3; Chen et al., 2015, figs. 7.16, 7.17.

Material examined.—Five specimens, MPC-33303–33307, from W01-50, three specimens, MPC-33308–33310, from E01-16, two specimens, MPC-33311, 33312, from E01-18, one specimen, MPC-33313, from E01-19, one specimen, MPC-33314, from E01-22, one specimen, MPC-33315, from E02-10, three specimens, MPC-33316–33318, from E02-11, twelve specimens, MPC-33320–33331, from E03-09, four specimens, MPC-33334–33337, from E03-10, one specimen, MPC-33338, from E03-11.

Description.—Rectangular segminate elements. Straight or slightly arched upper edge bears fused denticles with triangular tip that vary in number from 8 to 15; anteriormost denticle reclined anteriorly and the denticles increasingly recline posteriorly. Posterior denticles behind the cusp are smaller, lower and strongly reclined posteriorly making an abrupt posterior margin. Anterior lateral margin makes slant. Straight basal margin concave beneath basal cavity which shows symmetrical outline and variation in form: round, subrounded, oval, and subtriangular shapes. Some specimens show a lateral rib and flanged cap on a basal cavity. A groove runs from basal pit to anterior end.

Remarks.—The Japanese specimens of Novispathodus abruptus are characterized by fused denticles on a rectangular unit and variability of the symmetrical basal cavity. Symmetrical form of basal cavity of the species differs from that of Icriospathodus crassatus which usually has an asymmetrical basal cavity. Smaller element of Nv. abruptus is distinguished from Nv. pingdingshanensis by the orientation of the denticles, smaller basal cavity and rectangle unit. Some larger elements show a robust unit and develop a fine lateral flange and basal cap, but the mode of denticulation and symmetrical basal cavity are similar to the smaller elements.

Several specimens of Neospathodus homeri previously described from lower Spathian strata correspond to Novispathodus abruptus. Neospathodus homeri originally described from the upper Spathian by Bender (1970) is characterized by a laterally curved unit and posteriorly elongated lenticular basal cavity. The species was reclassified as Triassospathodus homeri (Bender, 1970) on the basis of its characteristic multielement apparatus (Orchard, 2005). True specimens of T. homeri generally occurred from the upper Spathian (e.g. Orchard, 1995).

Occurrence.—The species occurs from the uppermost Smithian to Spathian in Oman (Orchard, 1995), British Columbia (Orchard and Zonneveld, 2009), South China (Ji et al., 2011; Chen et al., 2013, 2015), northeastern Vietnam (the Xenoceltites variocostatus beds, the Tirolites cf. cassianus beds and the Tirolites sp. nov. beds within the Novispathodus ex gr. pingdingshanensis and Icriospathodus collinsoni zones, Shigeta et al., 2014 and Komatsu et al., 2016), and Southwest Japan (the Nv. pingdingshanensis and Nv. brevissimus zones, this study).

Neospathodus triangularis (Bender). Koike, 1981, pl. 1, fig. 6; Ding, 1983, pl. 5, figs. 15–17; Duan, 1987, pl. 3, fig. 6.

Neospathodus brevissimus Orchard, 1995, p. 119, figs. 3.14, 3.15, 3.20–3.22; Chen et al., 2015, fig. 8a, b.

Novispathodus triangularis (Bender), Maekawa and Igo, 2014, p. 240, figs. 172, 173, 174.1–174.30; Komatsu et al., 2016, fig. 5.8a–c.

Material examined.—Two specimens, MPC-33339, 33340, from W01-49, one specimen, MPC-33341, from E01-17, one specimen, MPC-33342, from E01-18, two specimens, MPC-33343, 33344, from E01-19, one specimen, MPC-33345, from E03-09, one specimen, MPC-33346, from E03-11.

Description.—Square segminate elements with length to height ratio of 1.1–1.6. Straight or slightly arched upper edge bears erect or radial, laterally compressed and fused denticles varying in number from 9 to 16. Largest specimen (Figure 19.6, MPC-33344) has some denticles with bifurcated tip. Undistinguished cusp situated in center or posterior of element. Denticles are subequal in size except for denticle at anterior end. Anterior lateral margin makes a slant. Straight anterior basal margin up-arched beneath basal cavity. Strongly expanded subtriangular or triangular basal cavity covered by robust cap and has deep pit; length of the cavity over half of element length; posterior margin of the cavity sometimes becomes concave anteriorly and makes a cordiform outline. Posterior lateral margin slightly or strongly curved. A groove runs from basal pit to anterior end.

Remarks.—According to Orchard (1995), Neospathodus brevissimus generally has a large subcircular basal cavity, but a paratype of the species (figs. 3.14, 3.15, GSC101634) shows a subtriangular outline of the basal cavity. The species is distinguished from Neospathodus triangularis by discrete and erect denticles and lack of a sharp fold in the basal cup. Both segminate elements of Neospathodus clinatus and Ns. curtatus have a longer blade and smaller basal cavity than does Ns. brevissimus.

The P₁ elements of Neospathodus triangularis reported by Koike (1981), Ding (1983) and Duan (1987) lack a conspicuous fold basal cap and are included here. Novispathodus triangularis reported by Maekawa and Igo (2014) also corresponds to Ns. brevissimus.

Occurrence.—In Southwest Japan and South China, Novispathodus brevissimus occurs with Nv. pingdingshanensis, and the range starts slightly later. In northeastern Vietnam, the species occurs with the Spathian ammonoid Tirolites sp. nov. and conodont Icriospathodus collinsoni (Shigeta et al., 2014; Komatsu et al., 2016). Thus, the range of the species probably starts in the early Spathian. The species was originally reported from the lower Spathian of Oman (Orchard, 1995).

aff. Neospathodus clinatus Orchard and Sweet in Orchard, 1995, p. 119, figs. 3.5–3.7.

Novispathodus aff. clinatus (Orchard). Chen et al., 2015, fig. 5.

Material examined.—One specimen, MPC-33347, from E01-15, one specimen, MPC-33348, from E01-17, three specimens, MPC-33351–33353, from E03-05.

Description.—Segminate elements length to height ratio 0.9–1.4. Rectangular unit bears subtriangular, uniformly reclined denticles, 6 to 7 in number, size and length gradually increase in length posteriorly. Undistinguished cusp situated posteriorly and lies at highest point of blade. Curved anterior basal margin concave beneath basal cavity and downturned at posterior end. Anterior lateral margin slants. Abrupt posterior margin showing bowed outline. Elliptical basal cavity forms drop-like outline. A groove runs from basal pit to anterior end.

Remarks.—Relatively short and small segminate P₁ element of Novispathodus clinatus characterized by variably developed fold in the basal cup was originally described from the Chiosella timorensis Zone of the Mianwali Formation in Narmia, Pakistan (Orchard, 1995).

Nv. aff. clinatus is reported from the Nv. pingdingshanensis Zone of the Luolou Formation in the Jiarong section, Guizhou Province, South China. The species differ from Nv. clinatus by its bowed posterior margin, droplike basal cavity, and lack of a fold in the basal cup. The species range is clearly earlier than Nv. clinatus. Japanese specimens resemble Nv. aff. clinatus from South China, and have a similar range.

Occurrence.—Novispathodus aff. clinatus has only been reported from South China (the Novispathodus pingdingshanensis Zone, Chen et al., 2015) and Southwest Japan (the Nv. pingdingshanensis and Nv. brevissimus zones, this study).

aff. Neospathodus curtatus Orchard, 1995, p. 119, figs. 3.8–3.13.

Material examined.—One specimen, MPC-33354, from W01-48, one specimen, MPC-33355, from E01-19, one specimen, MPC-33356, from E03-11.

Description.—Three segminate elements with length to height ratio of 1.8. Arched upper edge bears radial and fused denticles varying in number from 10 to 20. Height of element abruptly decreases in anterior one-fourth. In the larger specimen, the denticulate posterior margin curves downward to near the level of the basal margin. Basal margin slightly bowed in anterior and up-arched beneath basal cavity. The deep cavity forms a subtriangular or subpentagonal outline; length does not exceed one-third of element length; covered by thickened cap. A groove runs from basal pit to anterior end.

Remarks.—P₁ elements of Neospathodus curtatus described by Orchard (1995) are small segminate elements with a triangular basal cavity and strongly reclined posterior lateral margin due to restricted development of the basal margin. Japanese specimens are larger in size and develop a thick basal cap and so are differentiated as Nv. aff. curtatus. In addition, the range of Ns. curtatus generally starts more toward the upper part of the succession (Orchard, 1995).

Orchard (1995) suggested that Ns. curtatus evolved from Ns. abruptus and regarded it as the precursor of Ns. triangularis. Neospathodus abruptus is now classified in genus Novispathodus, to which genus I therefore assign Ns. curtatus.

Occurrence.—The Novispathodus brevissimus Zone of the Tahogawa Member (this study).

aff. Neospathodus eotriangularis Zhao and Orchard in Zhao et al., 2007, p. 35, fig. 7.

Material examined.—One specimen, MPC-33357, from E03-09.

Description.—One segminate element, 0.61 mm in length; 0.35 mm in height; length to height ratio 1.2. Arched upper edge bears nine separate anterior denticles and one broad posterior cusp. Basal margin up-arched anteriorly and slightly upturned beneath basal cavity. Anterior lateral margin slants and posterior lateral margin ends abruptly. A thickened posterior cap covers the asymmetrical and elliptical basal cavity. Deep groove runs from center of concave basal cavity to anterior end.

Remarks.—Neospathodus eotriangularis, characterized by a triangular outline and triangular deep basal cavity beneath a developed cap, was reported from the Columbites—Tirolites Zone of the Nanlinghu Formation, South China (Zhao et al., 2007). Lateral profile of Japanese specimen resembles that of the Chinese specimen (holotype), but the broad posterior cusp and elliptical basal cavity differ.

Occurrence.—The Novispathodus brevissimus Zone of the Tahogawa Member (this study).

cf. Neospathodus waageni Sweet, 1970b Morphotype 1, Orchard and Krystyn (2007), p. 31, pl. 1, figs. 8–10.

cf. Novispathodus latiformis Orchard and Zonneveld, 2009, p. 784, fig. 13, parts 11–13, 16, 17.

Material examined.—One specimen, MPC-33358, from W01-16.

Remarks.—Novispathodus latiformis is characterized by developed platform flanges that become progressively broader towards the posterior end. The Japanese specimen is poorly preserved, but its posterior wide flange is similar to the former species.

Occurrence.—The species occurs from the Novispathodus ex gr. waageni Zone of the Tahogawa Member (this study). The species also occurs from Spiti, India (Orchard and Krystyn, 2007) and British Columbia, Canada (Orchard and Zonneveld, 2009).

Neospathodus pingdingshanensis Zhao and Orchard in Zhao et al., 2007, p. 36, pl. 1, fig. 4A– C; Ji et al., 2011, figs. 4.7–4.9; Liang et al., 2011, figs. 1–3.

Novispathodus pingdingshanensis (Zhao and Orchard). Goudemand and Orchard in Goudemand et al., 2012, p. 1030, figs. 2B, F, I, J, M, Q, AD, 3T, U; Maekawa and Igo, 2014, p. 239, figs. 171.13–171.31; Chen et al., 2015, figs. 8.5, 8.6.

Novispathodus ex gr. pingdingshanensis (Zhao and Orchard). Komatsu et al., 2016, p. 72, figs. 5.4, 5.5.

multielement apparatuses, Novispathodus pingdingshanensis (Zhao and Orchard). Goudemand and Orchard in Goudemand et al., 2012, p. 1030, fig. 6.

Neospathodus robustus Koike. Chen and Kolar-Jurkověk in Chen et al., 2016, fig. 9.5.

Material examined.—One specimen, MPC-33359, from W01-48, one specimen, MPC-33360, from W01-49, one specimen, MPC-33362, from E01-15, one specimen, MPC-33363, from E01-16, five specimens, MPC-33364–33368 from E01-17, two specimens, MPC-33370, 33371, from E02-09, two specimens, MPC-33372, 33373, from E02-10, two specimens, MPC-33374, 33375, from E03-05, ten specimens, MPC-33376–33385, from E03-09, five specimens, MPC-33386–33390, from E03-10.

Description.—Small, laterally compressed segminate elements, length to height ratio 1.2–1.6. Arched upper edge bears mostly fused denticles with triangular tips, varying in number from 6 to 14, denticles gradually increase in size and recline posteriorly. Undistinguished cusp situated in posterior one-third with 1 to 3 small posterior denticles. Anterior basal margin straight or slightly upturned; posterior basal margin flat or up-arched beneath basal cavity. Anterior lateral margin slanted. Curved posterior lateral margin results from abruptly terminated posterior denticulation and elongated posterior margin of basal cavity. Large broadly expanded oval or subrounded basal cavity occupying more than half of element length. A groove runs from basal pit to anterior end.

Remarks.—The described specimens show variations in the number of small posterior denticles, form of the basal cavity, and upturned angle of the posterior basal margin. However, the denticulation and distinctive large basal cavity enable us to identify the specimens as Novispathodus pingdingshanensis.

A specimen described as Neospathodus robustus reported from Slovenia (fig. 9.5, Chen et al., 2016) is a square segminate P₁ element characterized by fused denticles with triangular tips and a large subrounded basal cavity. It is here regarded as an example of Novispathodus pingdingshanensis, which has not been reported from Europe previously.

Occurrence.—Novispathodus pingdingshanensis has mainly been reported from locales in the Far East Tethys such as South China and northeastern Vietnam (Zhao et al., 2007; Ji et al., 2011; Liang et al., 2011; Goudemand et al., 2012; Shigeta et al., 2014; Maekawa et al., 2014; Komatsu et al., 2016). In South China, some researchers advocate use of the species as the index fossil of the Smithian-Spathian boundary (SSB), although in northeastern Vietnam, according to Shigeta et al. (2014) and Komatsu et al. (2016), the range of the species starts in the uppermost Smithian Xenoceltites variocostatus beds and extends to the lower Spathian Tirolites sp. nov. beds. Thus, usage of Nv. pingdingshanensis as an index of SSB would require reassignment of some traditional Smithian ammonoids to the Spathian. Recently, the species was reported from the Panthalassa region (e.g. western Canada, Orchard and Zonneveld, 2009; western USA, Orchard, pers. comm.), but those reports lack a description and figure of the species. Thus, this is the first systematic report of the species from Panthalassa. The European species occurred from unitary association zone 4 (UA4) situated above the SSB indicated by positive excursion of δ13Ccarb in UA3 (Chen et al., 2016). According to Chen et al. (2016), highest value of δ13Ccarb (+7‰) in UA3 gradually decreased upward in UA4. The δ13C isotope pattern is similar to well known positive excursions around SSB globally. Thus, UA4 probably corresponds to the lower Spathian.

aff. Neospathodus radialis Zhao and Orchard in Zhao et al., 2008a, p. 212, pl. 1, fig. 1a–c; Liang et al., 2011, fig. 3.8.

aff. Novispathodus radialis (Zhao and Orchard). Goudemand et al., 2012, p. 1031, figs. 2U, Y.

Material examined.—One specimen, MPC-33391, from W01-49, one specimen, MPC-33392, from E01-15, one specimen, MPC-33393, from E03-09.

Description.—Segminate elements with length to height ratio of 1.3–1.5. Arched upper edge bears 10 to 13 strongly fused triangular erect denticles. The largest denticles occur in the medial region and progressively decrease in size to the posterior end. Two specimens (Figure 21.14, MPC-33391 and Figure 21.15, MPC-33392) have a laterally curved denticle at posterior end. Highest point situated in medial region. Tip of denticles pointed in the two smaller specimens and rounded in the largest specimen. Straight or upturned anterior basal margin up-arched beneath basal cavity. Larger elements show expanded cap above rounded basal cavity. Concave basal cavity has deep pit; a groove runs from the pit to the anterior end.

Remarks.—Triangular denticles and symmetrical large basal cavity are similar to Novispathodus radialis. However, the larger number (10 to 13, average 12) of the relatively smaller-size denticles in the Japanese material distinguish these specimens from Nv. radialis. The well developed basal cap of the described species also differs.

Occurrence.—The Novispathodus pingdingshanensis Zone to the Nv. brevissimus Zone of the Tahogawa Member (this study).

Neospathodus waageni Sweet, 1970b, p. 260, pl. 1, figs. 11, 12; McTavish, 1973, p. 300, pl. 2, figs. 11, 22. 25–28; Mosher, 1973, p. 172, pl. 20, fig. 5; Goel, 1977, p. 1094, pl. 2, figs. 1–4; Solien, 1979, p. 304, pl. 3, fig. 9; Buryi, 1979, p. 56, pl. 7, figs. 8, 9; Wang and Cao, 1981, pl. 2, fig. 26; Koike, 1982, p. 39, pl. 6, figs. 24–27; Matsuda, 1983, p. 88, pl. 1, figs. 6–10, pl. 2, figs. 1–7; Berry et al., 1984, p. 133, pl. 1, figs. 1–4; Dagis, 1984, p. 24, pl. 7 figs. 2–10, pl.8, figs. 1–7; Duan, 1987, pl. 2, figs. 7; Cao and Wang, 1993, p. 261, pl. 56, figs. 5, 11; Wang and Zhong, 1994, p. 402, pl. 1, figs. 12, 13; Nakrem et al., 2008, figs. 5.7, 5.8, 5.11, 5.14; Orchard, 2008, p. 40, figs. 8.1, 8.2, 8.8, 8.9; Beranek et al., 2010, figs. 6.22, 6.23.

Neospathodus waageni waageni Sweet. Zhao and Orchard in Zhao et al., 2007, p. 36, pl. 1, fig. 10A, B.

Neospathodus waageni eowaageni Zhao and Orchard in Zhao et al., 2007, p. 36, pl. 1, fig. 5A, B.

Neospathodus ex gr. waageni Sweet. Orchard and Krystyn, 2007, figs. 8–18; Igo, 2009, p. 194, figs. 152.14–152.19, 156.7–156.19.

Novispathodus waageni (Sweet). Orchard and Zonneveld, 2009, p. 785, fig. 13, parts 1–10, 14, 15; Goudemand and Orchard in Goudemand et al., 2012, p. 1031, figs. 3D, E, H, N, S, T.

Novispathodus ex gr. waageni (Sweet). Maekawa and Igo, 2014, p. 244, figs. 174.31–174.57, 175–178, 179.1–179.3, 179.7–179.12, 179.16–179.48, 180, 181.1–181.31; Maekawa et al., 2016, p. 201, figs. 5.8–5.12.

Novispathodus waageni waageni (Sweet). Chen et al., 2015, figs. 6.23, 7.11, 8.3, 8.8, 8.9, 8.11, 8.14.

Novispathodus waageni new subspecies A Goudemand, 2014, fig. 1A–D.

Material examined.—Six specimens, MPC-33394–33399, from W01-13, two specimens, MPC-33400, 33401, from W01-14, one specimen, MPC-33402, from W01-16, three specimens, MPC-33403–33405, from W01-17, one specimen, MPC-33406, from W01-21, one specimen, MPC-33407, from W01-25, one specimen, MPC-33410, from W01-27, two specimens, MPC-33411, 33412, from W01-30, one specimen, MPC-33413, from W01-49, one specimen, MPC-33414, from E01-01, one specimen, MPC-33415, from E01-14, two specimens, MPC-33416, 33417, from E01-15, one specimen, MPC-33418, from E01-16, two specimens, MPC-33419, 33420, from E01-17, three specimens, MPC-33421–33423, from E02-06, one specimen, MPC-33424, from E02-09, one specimen, MPC-33425, from E03-04, one specimen, MPC-33427, from E03-09, one specimen, MPC-33428, from E03-10.

Description.—Laterally compressed segminate elements with length to height ratio of 1.0–1.6. Arched upper edge bears 6 to 12 denticles; fused for half of the length; radial, erect or reclined posteriorly; in most specimens, 1 to 3 small denticles behind the cusp. Undistinguished cusp situated at the posterior half of element. Relatively large basal cavity forms rounded or subrounded outline; length of the cavity within a half of element length. Basal margin straight or slightly upturned anteriorly and upturned beneath basal cavity. Concave cavity with basal pit; a groove runs from the pit to anterior end.

Remarks.—Intraspecific variants of P₁ element of Novispathodus waageni were reported by some researchers (e.g. Goel, 1977; Matsuda, 1982; Zhao et al., 2004, 2007, 2008b; Orchard, 2007b; Orchard and Krystyn, 2007; Goudemand, 2014). According to those reports, six morphotypes and three subspecies (Nv. waageni waageni, Nv. w. eowaageni, Nv. waageni new subspecies A) are recognized. Orchard and Zonneveld (2009) separated Nv. waageni Morphotype 1 of the species, characterized by a platform flange progressively broader towards the posterior end, and newly named Nv. latiformis. Goudemand (2014) recovered Nv. waageni n. subsp. A, which is characterized by a suberect or radial fashion of denticulation and expanded elliptical basal cavity, from the two candidate sections (Spiti and South China) of GSSP of the Induan-Olenekian boundary (IOB). The FAD of Nv. ex gr. waageni has been proposed as the index for the IOB (Zhao et al., 2007, 2008b; Orchard, 2007a, 2010).

In the Tahogawa Member, Taho Formation, P₁ elements from the FO of Novispathodus ex gr. waageni (W01-13) comprise Nv. waageni n. subsp. A, and morphotypes 2 and 3 of the species (they correspond to Nv. waageni waageni and Nv. w. eowaageni, respectively). Novispathodus cf. latiformis occurs about 50 cm above the FO of Nv. ex gr. waageni (W01-16, -17), and Nv. ex gr. waageni Morphotype 4 occurs 120 cm above the same bed (W01-21). Nv. ex gr. waageni Morphotypes 5 and 6 were not recovered from the member. The range of Nv. ex gr. waageni Morphotype 2 continued to the upper part of the member and co-occurs with Nv. pingdingshanensis. Occurrences of morphotypes and subspecies of Nv. ex gr. waageni around the IOB are summarized in Figure 7.

Occurrence.—Novispathodus waageni is a well known Smithian species throughout the world, and its FAD has been proposed to define the IOB (Orchard, 2007a, b; Orchard and Krystyn, 2007; Zhao et al., 2007, 2008b; Shigeta et al., 2009; Orchard, 2010; Goudemand, 2014). According to Goudemand et al. (2012), Shigeta et al. (2014), and Komatsu et al. (2016), the species co-occurs with Nv. pingdingshanensis in the uppermost Smithian ammonoid beds. Thus, the range of the species is at least throughout the entire Smithian.

Novispathodus sp. nov. C Goudemand and Orchard in Goudemand et al., 2012, p. 1032, fig. 2O.

Material examined.—Two specimens, MPC-33429, 33430, from E01-15, one specimen, MPC-33431, from E03-09.

Description.—Segminate element length to height ratio 1.5–1.6. Slightly slanted upper edge bears progressively smaller and more reclined denticles posteriorly, 7 to 9 in number, isosceles triangle-shaped in anterior. Subterminal cusp of two specimen (MPC-33429, 33430) has a needle-like small posterior denticle. Basal margin straight or up-turned anteriorly and strongly upturned beneath basal cavity. Rounded or subrounded basal cavity, over a half of element length, covered by a slightly flanged cap. A groove runs from basal pit to anterior end.

Remarks.—P₁ element of Novispathodus sp. nov. C described by Goudemand et al. (2012) has a large basal cavity and a needle-like small denticle at the posterior end. Two described specimens lack the needle-like terminal small denticle, but their lateral profile and large basal cavity conform to Novispathodus sp. nov. C. Triangular anterior denticles and large basal cavity are similar to Novispathodus sp. nov. D Goudemand and Orchard in Goudemand et al., 2012, which differs in the radial fashion of its denticulation.

Occurrence.—This species occurs from South China (Goudemand et al., 2012) and Southwest Japan (the Nv. pingdingshanensis and Nv. brevissimus zones, this study).

Material examined.—One specimen, MPC-33432, from E01-15.

Description.—Segminate element 0.31 mm in length; 0.25 mm in height; length to height ratio 1.2. Reclined and fused denticles form arched upper edge; 8 in number; cusp situated behind the highest position. Anterior lateral margin slanted. Straight basal margin strongly downturned at posterior end. Oval basal cavity has deep pit, a groove runs from the pit to the anterior end.

Remarks.—The lateral form of the described specimen is similar to that of Nv. ex gr. waageni, but the strongly downturned posterior basal margin differentiates it from the latter.

Occurrence.—The species occurs from the Novispathodus pingdingshanensis Zone of the Tahogawa Member (this study).

Material examined.—One specimen, MPC-33433, from E01-15.

Description.—Subtriangular segminate element 0.33 mm in length; 0.18 in height; length to height ratio 1.9. Strongly reclined and fused triangular denticles form progressively higher upper edge; 9 in number. Largest terminal cusp has one small posterior denticle. Anterior lateral margin slanted. Straight basal margin slightly downturned at posterior end. Subrounded basal cavity occupying half of element length; has deep pit; a groove runs from the pit to the anterior end.

Remarks.—Lateral form of the described specimens is similar to that of Neospathodus pakistanensis, but it differs in having fused triangular denticles and a larger basal cavity.

Occurrence.—The species occurs from the Novispathodus pingdingshanensis Zone of the Tahogawa Member (this study).

Material examined.—One specimen, MPC-33434, from E01-17, one specimen, MPC-33435, from E03-10.

Description.—Two small rectangle-like robust segminate elements with length to height ratio 1.3 and 1.4. Short denticles, 7 and 8 in number, erect anteriorly and progressively reclined posteriorly; size gradually decrease to posterior. Anterior lateral margin slanted. Posterior lateral margin forms curved outline. Basal margin shows reverse sigmoidal form with anterior upturn and posterior up-arch. Drop-shaped wide asymmetrical basal cavity extends to anterior end. A groove runs from deep pit to anterior end.

Remarks.—The described element is similar to the P₁ element of Novispathodus brevissimus, but the Japanese specimens differ in their lower height of the element, upturned anterior basal margin, and larger basal cavity.

Occurrence.—The species occurs from the Novispathodus brevissimus Zone of the Tahogawa Member (this study).

Material examined.—One specimen, MPC-33436, from E03-09.

Description.—Robust segminate element 0.55 mm in length; 0.36 mm in height; length to height ratio 1.5. Anteriormost denticle is the highest point and the upper edge slopes to the cusp at the posterior end. Robust node-like denticles with pointed tip, 8 in number, erect and progressively reclined posteriorly. Initial and terminal denticles wider than the others. Basal margin straight in anterior and slightly up-arched beneath basal cavity. Subrectangular basal cavity, over half of element length, slightly concave. Deep furrow runs from basal pit to anterior end.

Remarks.—Highest initial denticle and lateral profile of described element is reminiscent of the genus Hindeodus, an important conodont in the Late Permian and earliest Triassic. However, the overall form of the described element, especially the lack of a posterior groove, enables us to distinguish the specimen from that genus.

Occurrence.—In this study, the described specimen was collected from the Novispathodus brevissimus Zone of the Tahogawa Member.

Type specimens.—Holotype, MPC-33437, from E01-15, paratype, one specimen, MPC-33438 from E01-15.

Material examined.—One specimen, MPC-33439, from E03-05.

Etymology.—Named after Shirokawa, town name at the type locality, Ehime Prefecture, western Shikoku, Southwest Japan.

Diagnosis.—Short subtriangular and robust segminate element, length to height ratio 1.0–1.1, with reclined upper edge and flattened reverse sigmoidal lower edge. Strongly fused pointed denticles, 6 to 7 in number, reclined posteriorly. Elliptical or drop-shaped large basal cavity covers over a half of element length.

Description.—Three small, short and robust segminate elements 0.25–0.31 mm, average 0.29 mm in length; 0.22–0.32 mm, average 0.28 mm in height; length to height ratio 1.0–1.1. Lateral profile of element subtriangular. Strongly fused denticles, 6 to 7 in number, with discrete pointed subtriangular tips; moderately reclined posteriorly. Denticle size and height gradually decrease from undistinguished cusp in both anterior and posterior directions. Flattened sigmoidal lower edge consists of gradually upturned anterior part and up-arched posterior part beneath basal cavity. Large, round or oval basal cavity covers three-fourths of element length; 0.14–0.17 mm, average 0.16 mm in width. A groove runs from deep pit to anterior end.

Remarks.—The characteristic elements of the new species are distinguished from Novispathodus brevissimus by the subtriangular shape in lateral view, smaller number of denticles, and round or oval basal cavity. Nv. pingdingshanensis differs from Nv. shirokawai by the mode and larger number of denticles. Novispathodus sp. 1 in this report closely resembles Nv. shirokawai, but the species differs by its slender unit and small basal cavity.

Occurrence.—The species occurs from the Novispathodus pingdingshanensis Zone of the Tahogawa Member (this study).

Type specimens.—Holotype, MPC-33445, from E03-05. Paratypes, three specimens, MPC-33446–33448, from E03-05.

Material examined.—Four specimens, MPC-33440–33443, from E01-15, one specimen, MPC-33449, from E03-09.

Etymology.—Named after Taho, regional name at the type locality in Shirokawa Town, Ehime Prefecture, western Shikoku, Southwest Japan.

Diagnosis.—Segminate element, length to height ratio 1.3–1.6, with arched upper edge. Rectangular base bears progressively reclined, discrete denticles, 5 to 9 in number. Posterior denticles strongly reclined posteriorly and result in a curved posterior margin. Straight basal margin up-arched beneath basal cavity with downturned posterior edge. Rounded basal cavity occupies half of element length.

Description.—Nine blade-like segminate elements 0.24–0.49 mm, average 0.32 mm in length; 0.17–0.32 mm, average 0.24 mm in height; length to height ratio 1.3–1.6, average 1.5. Arched upper edge bears discrete denticles with pointed tip, 5 to 9, average 7 in number; length, size and inclination of denticles gradually increases posteriorly. Largest specimen (holotype, MPC-33445) has robust denticles with blunt tip. Basal margin consists of straight anterior part, up-arched posterior part beneath basal cavity, and downturned posterior edge. Rounded large basal cavity has basal pit. A groove runs from the pit to the anterior end.

Remarks.—The described specimens is distinguished from Novispathodus sp. nov. A reported by Goudemand et al. (2012) by having fewer large discrete denticles. Nv. pingdingshanensis differs from Nv. tahoensis by its square unit and fused denticles. Novispathodus sp. 2 in this study differs by its shorter triangular denticles.

Occurrence.—The species occurs from the Novispathodus pingdingshanensis Zone to the lowest part of the Novispathodus brevissimus Zone of the Tahogawa Member.

Type species.—Neogondolella buurensis Dagis, 1984.

Remarks.—Neogondolella buurensis, holotype of the genus Borinella, has a gondola-like segminiplanate P₁ element with discrete denticles on the carina and blade, which is a common character of the genus (Orchard, 2007a, 2008). The multielement apparatus of the genus has never been reported.

aff. Neogondolella buurensis Dagis, 1984, p. 12, pl. 2, figs. 6–10, pl. 3, fig. 1, pl. 11, figs. 1–4, pl. 12, figs. 1, 2, p. 16, figs. 1–4.

aff. Borinella buurensis (Dagis). Orchard, 2008, p. 400, figs. 5.9–5.13.

Borinella aff. buurensis (Dagis). Goudemand and Orchard in Goudemand et al., 2012, p. 1032, fig. 2AA; Chen et al., 2015, fig. 9.11.

Material examined.—One specimen, MPC-33450, from E03-05.

Description.—Slender segminiplanate element, 0.57 mm in length, 0.19 mm in height; 0.11 mm in platform width; length to height ratio 2.9. Arched upper edge bears discrete and pointed denticles, 14 in number, gradually decreasing in size and length to the posterior. Undistinguished cusp situated at posterior end. Straight basal margin strongly downturned in posterior one-fourth of element. Linguiform platform covers posterior two-thirds of element; microreticulation covers platform; slightly constricted near posterior end; lateral furrow indistinct. Narrow basal keel runs from rounded flange surrounding a double pit to anterior end. A groove runs from the pits to anterior end. Posterior loop indistinct.

Remarks.—The slender segminiplanate element of the described specimen is similar to Borinella aff. buurensis reported from the Tsoteng section, South China by Goudemand et al. (2012). These differ from B. buurensis by the slender platform with narrower posterior end.

The slender P₁ element of Borinella aff. buurensis reported by Nakrem et al. (2008) from Svalbard clearly bends in an obtuse angle at the center. The feature is similar to B. buurensis. A specimen of B. aff. buurensis from the uppermost part of the Euflemingites romunderi Zone of the Canadian Arctic (Orchard, 2008) is larger (over 0.6 mm in length) with a straight basal margin and, like B. buurensis, has a wider platform and straight carina which curves inward at the posterior end. Thus, those two specimens differ from B. aff. buurensis reported from South China and Southwest Japan.

Occurrence.—The species was reported from the Novispathodus pingdingshanensis Zone of the Tsoteng section, South China (Goudemand et al., 2012), Jiarong section, Guizhou, South China (Chen et al., 2015), and Southwest Japan (this study).

Type species.—Eurygnathodus costatus Staesche, 1964.

Remarks.—All species of the genus Eurygnathodus were identified on the basis of disarticulated P₁ elements. The multielement apparatus of the genus is unknown.

Eurygnathodus costatus Staesche, 1964, p. 269, pl. 28, figs. 1–6; Budurov and Pantic, 1973, p. 51, pl. pl. 1, figs. 1–15; Igo, 2009, p. 183, figs. 152.23, 152.24; Orchard, 2010, figs. 5.9, 5.10; Maekawa and Igo, 2014, p. 220, figs. 161.4–161.6; Chen et al., 2015, fig. 8.4; Maekawa et al., 2015, p. 316, fig. 5.2; Chen et al., 2016, figs. 10.7–10.10, 11.3. 11.6, 11.7.

Platyvillosus costatus (Staesche). Goel, 1977, p. 1098, pl. 2, figs. 15–21; Wang and Cao, 1981, p. 371, pl. 2, figs. 1–4, 28, 29, 30, 33; Koike, 1982, p. 44, pl. 5, figs. 1–9; Tian et al., 1983, p. 391, pl. 81, fig. 2; Matsuda, 1984, p. 128, pl. 6, figs. 6–10; Duan, 1987, pl. 3, fig. 4; Koike, 1988, pl. 1, figs. 1–57, pl. 2, figs. 1–37; Bui, 1989, p. 411, pl. 31, figs. 7–9; Beyers and Orchard, 1991, pl. 5, fig. 10; Cao and Wang, 1993, pl. 56, fig. 16; Wang and Zhong, 1994, p. 404, pl.1, figs. 15, 23.

Platyvillosus paracostatus Wang and Cao, 1981, p. 371, pl. 2, figs. 9, 10.

Eurygnathodus hamadai (Koike). Chen et al., 2016, fig. 11.1.

Material examined.—Sixteen specimens, MPC-33451–33466, from W01-16, seven specimens, MPC-33467–33473, from W01-17, two specimens, MPC-33474, 33475, from W01-25, two specimens, MPC-33476, 33477, from W01-27, two specimens, MPC-33478, 33479, from W01-32.

Remarks.—Eurygnathodus costatus is a well known conodont in the early Smithian, and the typical P₁ element is characterized by transverse ridge-like denticles on a platform-like base. Morphological variation of the platform and ornamentation of the species was reported by Budurov and Pantic (1973), Goel (1977), Matsuda (1984), and Koike (1988). Koike (1988) showed the great variety of forms of ornamentation of the species from the Taho Limestone, Southwest Japan and split the species into the holotype form (Form A) and four morphotypes (Morphotype α, β, γ, δ) with fourteen forms (Form B–O). According to Koike (1988), Form A is characterized by transverse ridges covering the entire width of the platform, and the other forms show considerable variation (e.g. narrow ridge, nodose denticles, and faint ridge). Koike (1988) regarded the forms as intraspecific variants of the species. On the other hand, in Koike (1988), slender Form A, which shows a curved outline in upper view, occurred at the lowest level of the Taho Limestone (sample 1109). Platyvillosus paracostatus Wang and Cao, 1981 from the late Dienerian in South China probably corresponds to Form A.

In this study, we collected the specimens from the same section as Koike (1988) (Figure 7). Thinly bedded black to brown-colored, dolomitized micritic limestone of the report, 2.3 m thick, corresponds to dark gray and black bedded limestone (2.5 m thick) of the middle part of the Tahogawa Member, Taho Formation (Figure 7). Specimens corresponding to Platyvillosus paracostatus were recovered from the lowest level of the dark gray and black bedded limestone (sample 1109 of Koike, 1988), but, in our data, three morphotypes (α, β, δ) and typical Form A of E. costatus and E. hamadai are recovered from the lower levels of the bedded limestone (Locs. W01-16, -17). Thus, P. paracostatus probably corresponds to a variant of E. costatus.

In this study, the platform surface of some specimens is covered by microgranules (e.g. Figure 25.1d, MPC33451). It is a new feature of the species.

Occurrence.—In this study, the species indicates the Eurygnathodus costatus Subzone of the Novispathodus ex gr. waageni Zone of the Tahogawa Member. E. costatus Morphotype α has a longer range than the other morphotypes, but the range of E. costatus Morphotype γ is the shortest (Figure 7). The range of the species is limited to the early Smithian and it often co-occurs with the early Smithian ammonoid Flemingites (Zhao et al., 2007; Krystyn et al., 2007; Goudemand, 2014).

This species is also reported from South Tirol (Staesche, 1964), Spiti, India (Goel, 1977; Orchard and Krystyn, 2007; Orchard, 2010), South China (Wang and Cao, 1981; Wang and Zhong, 1994; Chen et al., 2015), Kashmir, India (Matsuda, 1984), Southwest Japan (Koike, 1988), northeastern Vietnam (Bui, 1989; Maekawa and Igo, 2014), South Primorye, Russia (Shigeta et al., 2009), Slovenia (Chen et al., 2016), and British Columbia, Canada (Beyers and Orchard, 1991).

Platyvillosus costatus (Staesche). Wang and Cao, 1981, p. 371, pl. 2, figs. 31–32.

Platyvillosus hamadai Koike, 1982, p. 45, pl. 5, figs. 10–36; Koike, 1988, pl. 2, figs. 38–45.

Eurygnathodus hamadai (Koike). Maekawa et al., 2015, p. 317, fig. 5.2.

Material examined.—Three specimens, MPC-33480–33482, from W01-16, one specimen, MPC-33483, from W01-33.

Remarks.—Eurygnathodus hamadai differs from E. costatus by its lack of ornamentation. Koike (1988) reported E. costatus Morphotype δ, characterized by a reduced ornamentation, as a probable transitional form between the two species. According to Koike (1988), both E. hamadai and E. costatus Morphotype δ occurred stratigraphically higher than the other morphotypes of E. costatus, but in this study both forms which contain small (juvenile) elements occurred at the lowest level of those species ranges, where the other two morphotypes (α and β) of E. costatus were recovered. Significantly, the geographic distribution of the species is more limited in the Tethyan region than that of E. costatus.

Occurrence.—The species occurs from the lower Smithian carbonates in China (Wang and Cao, 1981), Malaysia (Koike, 1982), Southwest Japan (Koike, 1988; this study), and Spiti, India (Orchard, 2007a; Orchard and Krystyn, 2007).

Type species.—Neospathodus collinsoni Solien, 1979.

Remarks.—The genus Icriospathodus was established for the characteristic P₁ element of I. collinsoni which has biserial or ridge-like denticulation on a relatively robust base. Orchard (2005) reconstructed the multielement apparatus of the species, which consists of 15 elements. P₂, S, and M elements of I. collinsoni have fewer denticles than those of Novispathodus. In this study, P₁ elements of I. crassatus and I. zaksi co-occur with Icriospathodus type S elements in some localities in the Novispathodus brevissimus Zone of the Tahogawa Member, Taho Formation. The affinity of I. collinsoni and the latter two species has often been noted (Koike, 1992; Orchard, 2007a; Maekawa and Igo, 2014), and here I regard the latter two species as a member of the genus Icriospathodus.

Icriodus Clark et al., 1964, pl. 60, fig. 1a, b.

Neospathodus sp. G Sweet et al., 1971, pl. 1, fig. 13; Buryi, 1979, p. 49, pl. 9, fig. 3a–c, pl. 18, fig. 4a, b.

Neospathodus collinsoni Solien, 1979, p. 302, pl. 3, figs. 10, 12–20.; Clark et al., 1979, pl. 1, figs. 11, 12; Duan, 1987, pl. 2, figs. 1–6; Cao and Wang, 1993, pl. 55, figs. 12, 13.

Neospathodus? collinsoni Solien. Koike, 1981, pl. 1, figs. 42–44.

Spathoicriodus collinsoni (Solien). Koike, 1992, p. 357–361, figs. 12.1–12.42, 12.44, 12.47–12.50, 13.8–13.37.

Icriospathodus collinsoni (Solien). Nakazawa et al., 1994, pl. 1, fig. 30; Orchard, 1995, p. 113, figs. 2.22–2.24; Lucas and Orchard, 2007, figs. 7.4–7.7, 7.13–7.15; Ji et al., 2011, fig. 4.5a–c; Maekawa and Igo, 2014, p. 260, figs. 186.10–186.22, 187–191, 192.1–192.6; Chen et al., 2015, figs. 9.1–9.4; Komatsu et al., 2016, fig. 5.9.

multielement apparatuses, Icriospathodus collinsoni (Solien). Orchard, 2005, p. 96, text-fig. 22A.

Material examined.—Four specimens, MPC-33484–33487, from W01-48, one specimen, MPC-33488, from W01-49, one specimen, MPC-33489, from W01-50, one specimen, MPC-33490, from E01-18, one specimen, MPC-33491, from E01-19, one specimen, MPC-33492, from E02-11, four specimens, MPC-33493–33496, from E03-11.

Description.—Robust segminate elements with length to height ratio of 2.1–4.0. Posteriorly elevated upper edge bears ridge-like and/or biserial denticles, 10 to 14, average 12 in number; width of denticles longest in middle portion; denticulation of wider specimens shows elongated rhomboid-like form in upper view. Basal margin straight or slightly up-arched. Larger specimens bear one to seven postero-lateral denticles or nodes on the laterally elongated posterior margin. Basal cavity shows form variations: parallelogram, subtriangular, rectangular with straight posterior margin. A basal groove runs from basal pit to anterior end.

Remarks.—P₁ element of Icriospathodus collinsoni is easily distinguished from that of Eurygnathodus costatus by the greater width of the basal cavity compared with that of the platform.

Occurrence.—In this study, the species indicates the Icriospathodus collinsoni Subzone of the Novispathodus brevissimus Zone of the Tahogawa Member. The subzone is recognized in the lower Spathian of Idaho (upper part of Zone 10 and Zone 11, Sweet et al., 1971), the Thaynes Formation, Utah (middle and upper part of the Platyvillosus Zone and the Neospathodus collinsoni Zone, Solien, 1979), Nevada (Clark et al., 1964; Lucas and Orchard, 2007), South Primorye (the Tirolites cassianus Zone, Buryi, 1979), South China (Duan, 1987; Ji et al., 2011), Svalbard (Hatleberg and Clark, 1984), the Bac Thuy Formation, northeastern Vietnam (Shigeta et al., 2014; Komatsu et al., 2016), and Oman (Orchard, 1995). According to those reports, I. collinsoni indicates the early Spathian and generally co-occurs with the early Spathian ammonoid Columbites.

Spathoicriodus collinsoni (Solien). Koike, 1992, p. 357, figs. 12.1–12.12, 12.43, 12.45, 12.46, 12.51–12.53, 13.1–13.7.

Neospathodus crassatus Orchard, 1995, p. 120, figs. 2.19, 2.25–2.57; Ji et al., 2011, fig. 4.2a–c.

Icriospathodus? crassatus (Orchard). Orchard, 2007a, p. 60, fig. 2; Maekawa and Igo, 2014, p. 267, figs. 192.7–192.9; Komatsu et al., 2016, fig. 5.10.

Icriospathodus crassatus (Orchard). Chen et al., 2015, fig. 9.12.

Neospathodus sp. Chen et al., 2015, fig. 7.15.

Triassospathodus symmetricus (Orchard). Chen et al., 2015, fig. 8.1.

Material examined.—One specimen, MPC-33497, from W01-49, two specimens, MPC-33498, 33499, from W01-50, one specimen, MPC-33500, from E02-11, five specimens, MPC-33501–33505, from E03-09, one specimen, MPC-33506, from E03-10, two specimens, MPC-33507, 33508, from E03-11.

Description.—Robust blade-like segminate elements with length to height ratio of 1.8–2.6; length to width ratio 5.0–7.7. Straight or dome-like upper edge bears node-like denticles reclined posteriorly or showing a radial pattern, vary in number from 8 to 13, on average 11, and contains smaller posterior denticles. Cusp undistinguished. Highest position situated in posterior part of element. Basal margin straight or slightly up-arched and slightly concave beneath basal cavity. Distinctive lateral flange forms developed cap on the cavity. Rounded, subrounded or subtriangular basal cavity, usually shows asymmetrical form, elongated posteriorly. A groove runs from basal pit to anterior end.

Remarks.—The described specimens are distinguished from Novispathodus abruptus by the lower height, nodelike denticulation and smaller basal cavity. Icriospathodus zaksi, a closely related species, differs from the longer I. crassatus by its wider base, larger basal cavity and the smaller number of denticles.

Occurrence.—This species occurs from the lower Spathian of Southwest Japan (Koike, 1992; the Novispathodus brevissimus Zone, this study), Oman, Idaho and California (Orchard, 1995), South China (the Neospathodus homeri Zone, Ji et al., 2011; the Icriospathodus collinsoni Zone, Chen et al., 2013, 2015), and northeastern Vietnam (the Tirolites sp. nov. beds in the Icriospathodus collinsoni Zone, Shigeta et al., 2014 and Komatsu et al., 2016).

Neospathodus zaksi Buryi, 1979, p. 60, pl. 18, fig. 3a, b.

Neospathodus triangularis (Bender). Perri and Andraghetti, 1987, p. 311, pl. 33, figs. 1–4.

Icriospathodus? zaksi (Buryi). Orchard, 2007a, p. 105, fig. 2; Maekawa and Igo, 2014, p. 267, figs. 192.10–192.29; Komatsu et al., 2016, figs. 5.2, 5.3.

Neospathodus robustus Koike. Chen and Kolar-Jurkověk in Chen et al., 2016, fig. 8.8.

Material examined.—One specimen, MPC-33509, from W01-49, one specimen, MPC-33510, from E01-19, four specimens, MPC-33511–33514, from E03-09, one specimen, MPC-33515, from E03-11.

Description.—Robust rectangular segminate elements with length to height ratio of 1.7–2.5; length to width ratio 3.0–5.3. Erect node-like denticles, 7 to 12, on average 10 in number, smallest denticle at posterior end on triangular-shaped robust base. Cusp undistinguished. Straight basal margin up-arched beneath basal cavity. Posterior margin coincides with that of the cavity. Laterally expanded basal cap covers subrounded or rectangular basal cavity. A groove runs from deep pit to anterior end.

Remarks.—Icriospathodus zaksi is probably the first representative of the genus. In Far East Russia and northeastern Vietnam, the species occurs from the upper Smithian ammonoid zones (see below), lower than the first occurrence of I. collinsoni and I. crassatus (Buryi, 1979; Shigeta et al., 2014; Komatsu et al., 2016). In this study, I. zaksi wholly appears in the Spathian, from the base of the Novispathodus brevissimus Zone with name-giver plus I. crassatus, Nv. abruptus, and Nv. pingdingshanensis. The datum probably suggests that the appearance of I. zaksi is earlier in the eastern Tethys than in the western Panthalassa.

Three robust elements of Neospathodus triangularis reported by Perri and Andraghetti (1987) from the southern Alps, Italy are probably synonyms of Icriospathodus zaksi. The robust segminate element of Neospathodus robustus reported by Chen et al. (2016) from Slovenia is similar to I. zaksi. According to those reports, the European specimens were recovered from the Spathian strata.

Occurrence.—This species occurs from South Primorye, Russia (upper part of the Anasibirites nevolini Zone and lower part of the Tirolites cassianus Zone, Buryi, 1979), the Werfen Formation, southern Alps, Italy (Perri and Andraghetti, 1987), the Bac Thuy Formation, northeastern Vietnam (the Novispathodus pingdingshanensis Zone in the Xenoceltites variocostatus beds, Shigeta et al., 2014 and Komatsu et al., 2016), and the Taho Formation, Southwest Japan (the Novispathodus brevissimus Zone, this study). According to those reports, the species range is from the late Smithian to early Spathian.

Material examined.—One specimen, MPC-33516, from W01-50, one specimen, MPC-33517, from E01-18.

Description.—Two rectangular blade-like elements respectively 0.49 and 0.57 mm in length; 0. 23 and 0.28 mm in height; 0.07 and 0.08 mm in width; 0.26 and 0.30 mm in width of basal cavity; length to height ratio 2.0 and 2.1. Straight upper edge bears erect triangular-shape denticles, 10 and 11 in number. Straight basal margin uparched under large subrounded basal cavity. Basal cap bears one pointed denticle on one side. A groove runs from basal pit to anterior end.

Remarks.—Postero-lateral denticles are typically reported from the species which belong to Icriospathodus, but the P₁ elements of this species are narrower than I. crassatus and I. zaksi. In this study, I tentatively identify it as an end-member of Icriospathodus.

Occurrence.—The species occurs from the Novispathodus brevissimus Zone of the Tahogawa Member.

Type species.—Gondolella milleri Müller, 1956.

Remarks.—Holotype of the genus, reported by Müller (1956), is a segminiplanate P₁ element which bears denticulation on lateral platform ribs that continue to transverse ridges on the platform surface. Kozur (1989) established it as a genus of the family Neogondolellidae. Orchard (2005) reconstructed the 15-element apparatus of ‘Gondolella’ mosheri and embedded it to the genus as Scythogondolella mosheri. Orchard (2008) and Orchard and Zonneveld (2009) described new species of the genus on the basis of disarticulated segminiplanate P₁ elements that commonly have a variable blade-carina and rounded basal loop.

Gondolella milleri Müller, 1956, p. 823, pl. 95, figs. 1–9; Clark and Mosher, 1966, p. 390, pl. 47, figs. 30–35; Nogami, 1968, p. 124, pl. 10, figs. 1–15, pl. 11, fig. 1; Matsuda, 1984, p. 123, pl. 3, figs. 1–4.

Gondolella eotriassica Müller, 1956, p. 823, pl. 95, figs. 10, 11.

Neogondolella milleri (Müller). Sweet et al., 1971, pl. 1, fig. 37; Mosher, 1973, p. 167, pl. 19, figs. 22, 23, 25; Buryi, 1979, p. 64, pl. 9. fig. 8, pl. 11, figs. 4, 6–8, pl. 15, pl. 16; Clark et al., 1979, pl. 1, fig. 14; Solien, 1979, p. 302, pl. 2, figs. 19–26; Tian et al., 1983, p. 370, pl. 94, figs. 2, 4; Berry et al., 1984, p. 133, pl. 1, figs. 12–21; Hatleberg and Clark, 1984, pl. 4, figs. 18, 19; Beyers and Orchard, 1991, pl. 5, fig. 11.

Neogondolella elongatus Sweet. Tian et al., 1983, p. 369, pl. 94, fig. 1.

Neogondolella mosheri (Kozur and Mostler). Dagis, 1984, p. 9, plate 4, fig. 1, pl. 12, fig. 3.

Neogondolella sp. Liang et al., 2011, fig. 3.10.

Scythogondolella milleri (Müller). Kozur, 1989, pl. 7, fig. 2; Orchard, 2008, p. 410, figs. 5.5–5.8; Nakrem et al., 2008, figs. 5.1–5.3; Orchard and Zonneveld, 2009, p. 786, figs. 15.1–15.5; Bondarenko et al., 2013, p. 61, figs. 5.6–5.14, 6.3.

Material examined.—One specimen, MPC-33518, from E01-14, eight specimens, MPC-33519–33526, from E02-06, one specimen, MPC-33527, from E02-08, three specimens, MPC-33528–33530, from E001.

Description.—P₁ element: Asymmetrical segminiplanate elements with length to height ratio of 2.2–2.8; length to width ratio 2.2–3.0. Straight or slightly curved carina bears short, pointed and reclined denticles, 10 to 13 in number, average number 12, reclined posteriorly and form arched upper edge. Entire basal margin slightly or strongly up-arched. Short free blade one-fourth to one-third of element length. Platform outline is a drop, rectangular, or leaf shape; irregular crinkle or denticles developed on inner or both sides of platform and often forms weak transverse ridge; strongly reclined cusp extends from posterior platform margin. Low keel shows drop-shaped outline with rounded posterior margin. Flange and loop developed. A groove runs from basal pit to anterior end.

P₂ element (Fig. 30.12, MPC-33526): Robust angulate element 1.07 mm in length; 0.48 mm in height; 0.18 mm in width for one specimen. Angular base bears strongly reclined discrete denticles with pointed tip, 14 in number, oblique to inner side. Cusp indistinct. Size and length of posterior denticles, behind the cusp, gradually decrease. In upper view, middle portion laterally flanged and posterior unit strongly curved to inner side. In lower view, a groove runs from basal pit to both anterior and posterior ends.

Remarks.—Scythogondolella milleri from the Taho Formation has irregular denticulations on one or both sides of the platform and is weaker than in the holotype and paratypes reported by Müller (1956), except for one broken specimen (Figure 30.6, MPC-33520). Specimens of the weak denticulation type were reported from Southwest Japan (Nogami, 1968), Far East Russia (Buryi, 1979), Utah (Solien, 1979) and British Columbia (Beyers and Orchard, 1991; Orchard, 2008). Kozur and Mostler (1976) named those specimens as subspecies Scythogondolella milleri parva and treated them as a transitional form from Scythogondolella mosheri (Kozur and Mostler, 1976). However, in this study I recognize those specimens as intraspecific variants of S. milleri, because S. mosheri has never been recovered from the Taho Formation.

Gondolella eotriassica, reported by Müller (1956), is an adult synonym of the species. Segminiplanate elements of Neogondolella elongatus of Tian et al. (1983), Ng. mosheri of Dagis (1984), and Neogondolella sp. of Liang (2011) bear denticulations on the lateral margins of the platform and/or transverse ridge on the platform. Thus, they are assigned to S. milleri.

P₂ element of Scythogondolella mosheri was reported by Orchard (2005) as an angulate P₂ element characterized by a short anterior process with a well developed cusp and platform flange. P₂ element from the Tahogawa Member is characterized by undistinguished cusp and a longer anterior process with a platform flange. I recognize the element as a part of Scythogondolella milleri on the basis of the anterior platform flange.

Occurrence.—In this study, the species indicates the Scythogondolella milleri Subzone of the Novispathodus ex gr. waageni Zone and co-occurs with late Smithian ammonoids such as Anasibirites sp. and Hemiprionites sp. in the Tahogawa Member, Taho Formation. The species also occurs from Crittenden Springs, Nevada (Müller, 1956), South Primorye (Buryi, 1979; Bondarenko et al., 2013), Nepal (Hatleberg and Clark, 1984), Tibet (Tian et al., 1983), Kashmir, India (Matsuda, 1984), British Columbia, Canada (Beyers and Orchard, 1991; Orchard, 2008; Orchard and Zonneveld, 2009), and South China (Liang et al., 2011).

Material examined.—One specimen, MPC-33531, from E02-08.

Description.—Segminiplanate element has strongly fused denticulation; 1.04 mm in length, 0.40 mm in height, 0.28 mm in width. In upper view, narrow platform shows asymmetrical outline and is slightly flared at middle part of element; carina curved inward at both anterior and posterior ends. In lateral view, anterior margin slanted; platform rib and basal margin undulated. In lower view, outline of wide keel pointed at anterior end, gradually broadens posteriorly and has subrounded posterior end; a groove runs from posteriorly positioned basal pit to anterior end.

Remarks.—The fused denticulation of the carina and drop-shaped keel of the described specimen is similar to that of Scythogondolella milleri, but it differs in the narrow, irregular platform that bears no denticulation and the undulated basal margin. A larger specimen of Wapitiodus robustus Orchard, 2005 reported by Orchard and Zonneveld (2009) differs from Scythogondolella? sp. 1 by the distinct oval basal cavity and discrete denticles.

Occurrence.—The Scythogondolella milleri Subzone of the Novispathodus ex gr. waageni Zone of the Tahogawa Member (this study).