The identification of sponges that lack a mineral skeleton is always highly challenging, especially for Hexadella species, which are also fibreless. Recently, the yellow species Hexadella pruvoti Topsent was identified as a cryptic species complex while the pink coloured Hexadella racovitzai Topsent showed two highly divergent lineages. We performed a COI phylogenetic reconstruction using 27 new Mediterranean Hexadella samples in order to confirm the presence of divergent lineages within both shallow-water species. Specimens were described with an integrative approach combining morphological and cytological investigations, biochemical profiling and assessment of natural toxicity in order to identify diagnostic characters for each taxon. H. topsenti, sp. nov. is distinguished from H. racovitzai by its colour, its surface network shape, divergent secondary metabolite patterns and toxicity values. H. crypta, sp. nov. differs from H. pruvoti by a different encrusting growth form when alive, and by distinctively colouring the ethanol fixative solution. In addition, H. pruvoti and H. crypta show different types of cells with inclusions as well as distinct metabolic fingerprints. Natural toxicity values, however, do not permit the separation of H. pruvoti and H. crypta. Our work shows that only the use of a combination of complementary tools can provide relevant descriptions for some problematic taxa.

Megadrymus Gross is an endemic seed bug genus that occurs in subtropical and tropical wet and dry rainforest on the eastern and northern coasts of Australia. The genus is revised with the redescription of the type species M. terraereginae Gross, the transfer of Brentiscerus tenuicornis (Gross) to Megadrymus, and the description of five new species: M. aurorae, sp. nov., M. brunneus, sp. nov., M. capeyorkensis, sp. nov., M. kakadu, sp. nov. and M. refugiensis, sp. nov. A key to species is included. A phylogeny, and biological and distributional information, are presented and discussed.

Three new species of the Afrotropical genus Ventrops Crosskey, 1977 (V. aethiopicus, sp. nov., V. freidbergi, sp. nov. and V. stuckenbergi, sp. nov.) are described, and all seven known species are included in a morphology-based phylogenetic analysis both to provide a rigorous argumentation for the generic affiliation of the newly described species, and to provide a first explicit hypothesis of phylogenetic relationships between the included species. Also, by including exemplar species from several genera of the Rhinophoridae as outgroups, this analysis is the first explicitly phylogenetic definition of the genus Ventrops within a broader systematic context. The seven species of Ventrops are arranged in three species groups (milichioides-group, hannemariae-group and aethiopicus-group).

A new species of the genus Hirudinaria from Thailand is distinguished from its congeners by the dorsal colour pattern and reproductive structures. Scanning electron microscopy provided novel information on the jaw morphology of Hirudinaria bpling, sp. nov. and also of the previously described Hirudinaria manillensis. During the study, the genus name Hirudinaria in reference to leeches was found to be a homonym and, in this case, precedence is reversed. Phylogenetic analyses based on the nuclear genes 18S rDNA and 28S rDNA as well as the mitochondrial genes 12S rDNA and cytochrome c oxidase I, supported the new species as nested within the monophyletic genus Hirudinaria. Two individuals from the Caribbean, nominally identified as H. manillensis, included in the phylogenetic analyses were strongly supported as members of that species.

Dactylotrochus cervicornis (= Tridacophyllia cervicornis Moseley, 1881), which occurs in Indo-Pacific waters between 73 and 852 m, was originally described as an astraeid but was later transferred to the Caryophylliidae. Assumed to be solitary, this species has no stolons and only one elongated fossa, and is unique among azooxanthellate scleractinians in often displaying extremely long thecal extensions that are septate and digitiform. Based on both molecular phylogenetic analyses (partial mitochondrial CO1 and 16S rDNA, and partial nuclear 28S rDNA) and morphological characteristics, we propose the transfer of D. cervicornis from the Caryophylliidae to the Agariciidae, making it the first extant representative of the latter family that is solitary and from deep water (azooxanthellate). The basal position of D. cervicornis within the agariciids implied by our analyses strengthens the case for inclusion of fossil species that were solitary, such as Trochoseris, in this family and suggests that the ancestor of this scleractinian family, extant members of which are predominantly colonial and zooxanthellate, may have been solitary and azooxanthellate.

The biogeographic relationships among the Cantacaderinae (Heteroptera) are revisited in the light of a genus and species recently described. The results are reasonably congruent with previous studies, but with some differences. The common ancestor of Cantacaderinae may not be restricted to Australia but to a more widely distributed taxon. The Cantacaderinae evolved into two lineages: the Ceratocaderini   Carldrakeanini, originating in the Australia–New Zealand complex; and the Cantacaderini, originating in the Oriental region and dispersing through a south-eastern arc of continental fragments but not through the Asian peninsula.

Published research on the diversity and evolutionary history of Arthropoda sets a high standard for data collection and the integration of novel methods. New phylogenetic estimation algorithms, divergence time approaches, collaborative tools and publishing standards, to name a few, were brought to the broader scientific audience in the context of arthropod systematics. The treatment of morphology in these studies, however, has largely escaped innovation. Lodes rich in characters too often go unexplored, phenotype concepts are published with inadequate documentation and the way observations are textualised leaves them inaccessible to a majority of biologists. We discuss these issues, using data from recent arthropod systematics publications, and offer several that stand to restore the broad utility of morphological data. Specifically, we focus on: (1) the potential of internal soft-part characters and how to integrate their observation into arthropod systematics projects through dissection and serial sectioning; (2) the importance of capturing observations in images, especially using relatively new approaches, like laser scanning confocal microscopy and three-dimensional reconstruction; and (3) the untapped potential of established knowledge representation methods, which may help make the descriptive components of arthropod systematics research more accessible to other domains.