Phylogenetic relationships of two morphologically similar scolopendrid genera, Rhysida Wood, 1862, and Alluropus Silvestri, 1912, were investigated based on broad-scale taxonomic sampling from SE Asia, India and Australia. Morphological revision and molecular phylogenetics using three loci validate seven Rhysida species in SE Asia and Australia: R. lithobioides (Newport, 1845), R. longipes (Newport, 1845), R. immarginata (Porat, 1876), R. nuda (Newport, 1845), R. carinulata (Haase, 1887), R. singaporiensis Verhoeff, 1937 and R. polyacantha Koch, 1985. The nominal SE Asian species R. leviventer Attems, 1953 and R. marginata Attems, 1953 are placed in junior subjective synonymy with R. lithobioides and Alluropus calcaratus (Pocock, 1891), respectively. The monotypic genus Alluropus is redescribed, molecular phylogeny recovering it nesting together with Indo-Australian Rhysida. Taxonomic revision reassigned R. calcarata Pocock, 1891 to Alluropus based on its morphological and molecular similarity to the type, A. demangei Silvestri, 1912, the differences between putative species being sexual variation. Two morphologically distinct allopatric populations of A. calcaratus, comb. nov. (= A. demangei, syn. nov.) were found in the Indochina subregion. Phylogenetic relationships in Otostigminae remain unsettled because clades within several genera lack significant support, although Rhysida consistently falls into two clades that are not each other’s closest relative.

Hesionidae Grube, 1850 currently comprises over 175 species in 28 genera, placed in several subfamilies. Discoveries in recent years have largely been of deep-sea taxa. Here we describe a further four new hesionid species, mainly from methane ‘cold’ seeps at around 1000–1800 m depths off the Pacific coast of Costa Rica and new record of another species. Several of these taxa also occur at methane seeps in the Guaymas Basis (Mexico) and off the USA west coast (California and Oregon). The phylogenetic relationships within Hesionidae are reassessed via maximum parsimony and maximum likelihood analyses of DNA sequences from nuclear (18S rRNA and 28SrRNA) and mitochondrial (16SrRNA and Cytochrome c oxidase I) loci for the new samples. On the basis of these results, we refer one of the new species to Gyptis Marion & Bobretzky in Marion, 1874, one to Neogyptis Pleijel, Rouse, Sundkvist & Nygren, 2012, and two to Sirsoe Pleijel, 1998. The new species Gyptis robertscrippsi n. sp., Neogyptis jeffruoccoi n. sp., Sirsoe dalailamai n. sp. and Sirsoe munki n. sp. We refer to a collection of individuals from seeps ranging from Oregon to Costa Rica as Amphiduropsis cf. axialensis (Blake & Hilbig, 1990), even though this species was described from hydrothermal vents off Oregon. Neogyptis jeffruoccoi n. sp. was generally found living inside the solemyid clam Acharax johnsoni (Dall, 1891). The position of Hesiolyra bergi Blake, 1985 is resolved on the basis of newly-collected specimens from near the type locality and, as a result, Hesiolyrinae Pleijel, 1998 is synonymized with Gyptini Pleijel, 1998 (and Gyptinae Pleijel, 1998).

Speciation in subterranean habitats is commonly explained as the result of divergent selection in geographically isolated populations; conversely, the contribution of niche partitioning in driving subterranean species diversification has been rarely quantified. The present study integrated molecular and morphological data with a hypervolume analysis based on functional traits to investigate a potential case of parapatric speciation by means of niche differentiation in two sibling spiders inhabiting contiguous subterranean habitats within a small alpine hypogean site. Troglohyphantes giachinoi, sp. nov. and T. bornensis are diagnosed by small details of the genitalia, which are likely to be involved in a reproductive barrier. Molecular analysis recovered the two species as sister, and revealed a deep genetic divergence that may trace back to the Messinian (∼6 million years ago). The hypervolume analysis highlighted a marginal overlap in their ecological niches, coupled with morphological character displacement. Specifically, T. giachinoi, sp. nov. exhibits morphological traits suitable for thriving in the smaller pores of the superficial network of underground fissures (Milieu Souterrain Superficiel, MSS), whereas T. bornensis shows a greater adaptation to the deep subterranean habitat. Our results suggest that different selective regimes within the subterranean environment, i.e. deep caves v. MSS, may either drive local speciation or facilitate contiguous distributions of independently subterranean adapted species.

Molecular phylogenetics provides objective references for zoological systematics which sometimes are inconsistent with morphological data. This applies particularly for some primitive phyla such as Cnidaria. The marine hydrozoan Symplectoscyphus turgidus (Sertularellidae) is a recent questionable case reported to occupy an unexpected phylogenetic position and suggested to belong to a new genus. However, its position, based on a single Californian specimen, seemed doubtful. Here we contributed 16S, 18S and 28S rRNA data of another morphologically related species from the Yellow Sea, forming a monophyletic clade with the Californian sample, confirming the clade stability. Further integrative analyses support describing this clade as the new genus Xingyurella, gen. nov., and lead to a taxonomic revision of species characterised by three hydrothecal marginal teeth and strong gonothecal spines. This resulted in a new species and three new combinations: Xingyurella xingyuarum, sp. nov., X. gotoi, comb. nov., X. pedrensis, comb. nov. and X. turgida, comb. nov. Future investigations are required to understand the evolution and speciation involved in the transoceanic distribution pattern of Xingyurella. The approach used herein for dealing with non-monophyletic conditions may be indicative for further studies by integrating trophosome and gonosome traits for Sertularellidae and other hydrozoans.

The Mediterranean black coral fauna includes type species of four antipatharian genera belonging to four different families, therefore phylogenetic studies hold great potential for enhancing systematics within the order. The analysis of six Mediterranean antipatharian species by means of nuclear sequence data of internal transcribed spacer (ITS1 and ITS2) rDNA confirms the separation into different families, as was previously noted on a morphological basis, with a clear distinction of the family Leiopathidae, whose position is supported by a unique number of mesenteries and lack of spines on thicker ramifications. The position of a newly recorded black coral species for the Mediterranean basin belonging to the genus Phanopathes is discussed. Antipathes dichotoma, the type species of the genus Antipathes, on which the order Antipatharia was based, does not group with other members of the family Antipathidae. Supporting a recent finding based on mitochondrial markers, this suggests a critical need for revision of the families that will be impacted by reassignment of this nomenclaturally important taxon.

Termites are eusocial insects currently classified into nine families, of which only Stylotermitidae has never been subjected to any molecular phylogenetic analysis. Stylotermitids present remarkable morphology and have the unique habit of feeding on living trees. We sequenced mitogenomes of five stylotermitid samples from China and Taiwan to reconstruct the phylogenetic position of Stylotermitidae. Our analyses placed Stylotermitidae as the sister group of all remaining Neoisoptera. The systematic position of Stylotermitidae calls for additional studies of their biology, including their developmental pathways and pheromone communication, which have the potential to change our understanding of termite evolution.

Recent research of cave Collembola in Dinaric karst resulted in discovery of high regional diversification of the genus Verhoeffiella Absolon, 1900. The most striking feature of Verhoeffiella species is the high number of troglomorphic traits, which makes this genus a good model for studying morphological diversification and adaptation in subterranean environments. We explore the expression of various morphological modifications assumed to be linked to subterranean life, through detailed descriptions of four new species and redescription of two species including the type species of the genus. Species delimitations are confirmed by single locus (cytochrome c oxidase I) tree-based (Poisson tree processes) and distance-based (automatic barcode gap discovery) species delimitation approaches, which gave identical results. Morphological changes classically considered as adaptive for cave life and new, potentially troglomorphic characters for Collembola are discussed. For several of these characters, high morphological diversity between species and large decoupling in the development of different traits within species are recorded. Such a decoupling is also illustrated in the finding of two cases of Verhoeffiella species pairs at different levels of troglomorphy living in syntopy. We further provide several new differential characters of specific and possibly generic or supra-generic importance and describe for the first time among Collembola an original ‘distal organ’ on Ant. IV.

Nitor Gude, 1911 is a genus of helicarionid land snails currently comprising eight species ranging from southern New South Wales to northern Queensland. We comprehensively revise the taxonomy of this group based on comparative morphology and on mitochondrial genes cytochrome c oxidase subunit I and 16S rRNA, provide a new generic diagnosis, revise species descriptions and describe four new species. Two species, ‘N.’ reisi Stanisic, 2010 from northern Queensland and ‘N.’ whitneyae Stnaisic, 2010 from mid-eastern Queensland, are removed from Nitor. Revised species descriptions are given for N. subrugatus (Reeve, 1852), N. medioximus Iredale, 1941, N. circumcinctus (Cox, 1868), N. wiangariensis Hyman, 2007 and N. pudibundus (Cox, 1868); N. helmsianus Iredale, 1941 (previously considered a synonym of N. subrugatus) is reinstated; and new species N. glenugie, N. sheai, N. benjamini and N. pipinna are described. Helix graftonensis Cox, 1864 is synonymised with N. subrugatus. We demonstrate that Nitor is closely related to Lord Howe Island taxa Epiglypta Pilsbry, 1893, Gudeoconcha Iredale, 1944, Howearion Iredale, 1944 and Parmellops Iredale, 1944; the five genera are united by a combination of characters including the presence of a distinct vagina, a slender epiphallic flagellum forming a simple spermatophore and an epiphallic caecum with terminal attachment of the penial retractor muscle.

The phylogeny of the genus Roquettea Mello-Leitão, 1931 and its position in Discosomaticinae are investigated. The monophyly of an expanded Roquettea is for the first time tested and corroborated. The internal relations of Roquettea are elucidated by means of a morphological maximum parsimony cladistic analysis. Synapomorphies for the genus include: pedipalpal tibia forming long lobe projected anteriorly; supranumerary ventral plate macroseta grouped with macrosetae C; penis ventral plate projections and stylus with beak. New characters are proposed for the Cosmetidae species and genera, and special focus is placed on the finer study of the glans complex, with a fresh proposal of homology for its constituent parts and their evolution in the light of the topology proposed here. Roquettea bubalina, sp. nov. and Roquettea troguloides, sp. nov. are described respectively from the Brazilian states of Mato Grosso and Pará. Both species present unique dorsal protuberances and unusual ocularia. New material of previously described species of Roquettea is available, increasing our knowledge on the genus. The following new semaphoronts are described and illustrated: β male of R. carajas Kury & Ferreira, 2012; females of R. decioi Kury, 2013, R. taurina Ferreira & Kury, 2010 and of R. jalapensis Ferreira & Kury, 2010. An emended diagnosis and an identification key are provided for the species of Roquettea including all known semaphoronts.

Species constituting the family Echiniscidae are highly derived, armoured and inhabit terrestrial habitats, in contrast to other heterotardigrades that are predominantly marine. The genus Echiniscus C.A.S. Schultze, 1840, nominal for the family Echiniscidae, is currently the most speciose tardigrade genus. However, the great morphological variability, in comparison with other heterotardigrade genera, suggests the polyphyletic character of the genus. Here, we analyse new specimens of Echiniscus pseudelegans Séméria, 1994 collected in Japan and conclude that the species as well as two other related taxa, E. elegans Richters, 1907 and E. latifasciatus Dudichev and Biserov, 2000, represent a new genus, Stellariscus, gen. nov. The new genus is characterised by a mixture of peculiar morphological apomorphies: black eyes, star-like dorsal plate sculpturing, no trunk appendages (only cephalic cirri present), two types of ventral plates, and striking sexual dimorphism in both qualitative and quantitative traits. Morphological phylogeny of the family Echiniscidae suggests a close affinity between Stellariscus, Hypechiniscus Thulin, 1928 and Pseudechiniscus Thulin, 1911. The polyphyletic status of both Echiniscus and Testechiniscus Kristensen, 1987 is also inferred. The taxonomic significance of ventral armature in echiniscid phylogeny and taxonomy is discussed.