A recent phylogenetic study based on DNA sequence data (COI   18S rDNA) together with basic morphological characteristics demonstrated the presence of four novel lineages within the widely distributed South African velvet worm species Peripatopsis moseleyi sensu lato (Onychophora, Peripatopsidae). In the present study, the morphological variation within P. moseleyi (Wood-Mason, 1879) is quantified and the novel species delineated and described. A total of 31 new specimens were collected from the Amathole Mountains in the Eastern Cape while a further 12 specimens were collected from Mount Currie Nature Reserve, KwaZulu-Natal, South Africa. These samples together with selected specimens from the DNA study material were subjected to scanning electron microscopy (SEM) to investigate the presence of diagnostic morphological characters that could potentially be utilised in the delineation of the four novel lineages. The species diagnosis of P. moseleyi (Wood-Mason, 1879) is elucidated and amended since the original type description is inadequate and could apply to several Peripatopsis taxa. A neotype for P. moseleyi is designated because the syntypes appear lost. Four new species of Peripatopsis Pocock, 1894 are described; viz. Peripatopsis birgeri, sp. nov., P. hamerae, sp. nov., P. janni, sp. nov. and P. storchi, sp. nov.

The putatively ancient subterranean crustacean family Parabathynellidae has been poorly studied, in part because of the problem of obtaining material from difficult to access subterranean habitats in which they live. Further, the systematics of the group has been complicated by their generally simplified morphology and isolated descriptions of new taxa in the absence of any phylogenetic framework. Using material from comprehensive field surveys and mitochondrial cytochrome c oxidase subunit I (COI) and nuclear 18S sequence data, plus morphology, a new genus is recognised, Arkaroolabathynella Abrams & King, gen. nov., from underground waters in the Flinders Ranges, South Australia. Arkaroolabathynella contains four genetically and morphologically distinct species, described as A. bispinosa Abrams & King, sp. nov., A. remkoi Abrams & King, sp. nov., A. robusta Abrams & King, sp. nov. and A. spriggi Abrams & King, sp. nov. Phylogenetic analysis also revealed a previously unknown diversity of parabathynellids from southern Australia, and a complex set of relationships with the eastern (New South Wales) and south-western (Western Australia) continental faunas. Additionally, this study showed that deep molecular divergences in parabathynellids are not always reflected in morphological divergence. A checklist to Australian parabathynellid genera and species is also provided.

The freshwater isopod genus Amphisopus is one of only two phreatoicidean genera in Western Australia with wide distributions and containing multiple described species. Two species (Amphisopus annectans and A. lintoni) are known from the south-western part of the state. With recent sampling extending the known range of Amphisopus and the recorded possibility of an undescribed species, this study aimed to examine genetic species boundaries and to detect additional species diversity. Isopods were sampled from across the range, and genetic structure was examined using mtDNA sequence data from a COI fragment and data from ten polymorphic allozyme loci. While allozyme data supported the clear separation of the known species, phylogenetic analyses presented three divergent monophyletic, geographically restricted clades occurring in the western, eastern and central parts of the Amphisopus distribution. These corresponded to A. annectans, A. lintoni and an undescribed species, respectively. The latter’s status was supported by its phylogenetic position relative to the known species and by the extent of differentiation observed among other phreatoicidean taxa. As with other taxa from the region, divergence times among these three species supported aridity in the Miocene–Pliocene as a driver of diversification, and suggested the existence of wetter refugial areas in south-western Australia.

A comprehensive phylogenetic analysis of the Terebellidae and related families was undertaken. Type material of all genera of Terebellinae was examined, together with representatives of nearly all genera of remaining Terebellidae subfamilies, and representatives of the families that have been traditionally regarded as being closely related, comprising the Terebelliformia. In total, 85 species were coded using 118 subjects (‘characters’) and 286 subject–predicate relations (‘states’). The results indicate: (1) the paraphyly of Terebellidae by the placements of Trichobranchidae, Ampharetidae, Alvinellidae and Pectinariidae within that clade; (2) the occurrences of Thelepodinae as separate clades, consistent with groups ‘A’ and ‘B’ recognised by Nogueira et al. (2010a); and (3) the monophyly of Polycirrinae and Terebellinae. The previously considered subfamilies of Terebellidae are raised to familial level and a new family is described. Revised definitions are provided for: Terebelliformia, Polycirridae, stat. nov., Telothelepodidae, fam. nov., Terebellidae emend., and Thelepodidae, stat. nov., along with a discussion of character evolution in the Terebellidae.

A revised molecular phylogeny of the genus Aleochara Gravenhorst is presented. The dataset comprised partial mitochondrial cytochrome c oxidase I (COI) (1373 bp), COII (577 bp), and the complete sequences of tRNA leucine (71 bp) between them, for 56 Aleochara species and 8 outgroups. We added 15 populations of 8 coastal species: A. fucicola Sharp, A. littoralis (Mäklin), A. nubis (Assing), A. puetzi (Assing), A. squalithorax Sharp, A. sulcicollis Mannerheim, A. trisulcata Weise and A. zerchei (Assing). All phylogenetic analyses strongly supported the monophyly of the genus Aleochara, a curtula clade, a bilineata clade, and four other clades (A–D, described later) containing the coastal species. Based on the phylogenies, we hypothesise that there are four independent origins of specialisation to a coastal habitat in the genus Aleochara (clades A–D). Clade A (Emplenota and Triochara), with nine species, is the most successful lineage in terms of species number and broad distribution range.