Invertebrate Systematics

The taxonomic status of the freshwater razor clam Novaculina siamensis Morlet, 1889 is determined using molecular and morphological analyses. Phylogenetic analyses placed the species separately from other currently recognised Novaculina species. Additionally, N. siamensis also possesses distinct morphological characteristics including fused, fringed siphons instead of separated, smooth siphons, as found in the type species of Novaculina s.s. Therefore Cenonovaculina gen. nov. is proposed to accommodate ‘N. siamensis’. (Image credit: Kongkit Macharoenboon.)

The shrimps of Palaemonella and related genera (family Palaemonidae) were revised based on multigene phylogenetic analysis. The genus was revealed to be a diverse paraphyletic group. The shrimps of Eupontonia and Vir were therefore synonymised with Palaemonella. The Atlantic Cuapetes americanus was also transferred into Palaemonella, as well as Periclimenes rhizophorae (which had long been a synonym of C. americanus). The number of known representatives of Palaemonella has increased from 27 to 38 species. (Photographs by: left, A. Anker; right, I. Horká.)

The family Deltocyathidae was recently erected to accommodate Deltocyathus species previously ascribed to Caryophylliidae but Deltocyathus magnificus was phylogenetically recovered within the family Turbinoliidae. Mitochondrial and nuclear sequence data, used for phylogenetic reconstructions, were obtained for 10 Deltocyathidae and Turbinoliidae species. Deltocyathus magnificus is moved to Turbinoliidae and ascribed to the new genus Dennantotrochus. A new mitochondrial gene order is described for Deltocyathus species. Macromorphological features indicate skeletal convergence and microstructural analyses demonstrate possibly conserved biomineralisation mechanisms. (Image credit: C. F. Vaga.)

Northern estuarine populations of Gammarus have given southern siblings the cold shoulder. Cryptic species have been discovered across a variety of organisms, from parasites to giraffes, with wide implications from human to ecosystem health. Our study supports the existence of a cryptic complex within the amphipod species Gammarus tigrinus and G. daiberi due to formation of the Labrador Current (c. 3 Ma). Gammarus tigrinus is highly invasive in Europe, highlighting the need to assess the potential for cryptic diversity of invading populations. (Image credit: Andrew G. Cannizzaro.)

Transfer of key species in the tapeworm order Rhinebothriidea to Semiorbiseptum and its assignment to the family Escherbothriidae greatly affects our understanding of how tapeworms evolved. Some species that parasitise skates have been assigned to a variety of rhinebothriidean genera without prior confirmation using phylogenetic analyses, thus obscuring patterns of host associations. We present evidence that skate-hosted rhinebothriidean taxa are restricted to the families Echeneibothriidae and Escherbothriidae. We believe our findings provide a robust foundation for future research into the diversification of tapeworms within the Rhinebothriidea and beyond. (Image credit: Veronica M. Bueno.)

House centipedes are conspicuous yet often ignored myriapods for which little work has been conducted in southern South America. After examining recent and museum collections from Chile and Argentina, a new genus of scutigerid centipede, Edgethreua, is described with two new species from Central Chile and Argentinian Patagonia. A phylogenetic analysis of the new species using five molecular markers shows that the new genus does not cluster with any other described genus of scutigeromorph represented in molecular phylogenies. This new genus is likely sister group to a clade including the genera Lassophora, Ballonema and the subfamily Thereuoneminae, although another analysis suggests a position as sister group to Scutigerinae. (Image credits: picture, A. Porta; tree, G. Giribet.)

The debatable identity and delimitation of spider species of Mastigusa have confused the taxonomic status and distribution. Broad sampling, and morphological and molecular techniques were used to revise the species’ statuses. Three Mastigusa species were recircumscribed and redescribed, and the distributions updated. Based on a reexamination of type material, Mastigusa diversa O. Pichard-Cambridge, 1893 is revalidated. Mastigusa shows strong ecological plasticity, and understanding the species delimitations and distributions will unravel drivers of extreme lifestyles such as myrmecophily and cave-dwelling. (Image credit: F. Castellucci.)

Adult forms of y-larvae (Pancrustacea: Facetotecta) remain unknown despite discovery more than 100 years ago and global occurrence. Likewise, the evolutionary history of y-larvae remains almost entirely unknown due to a critical lack of molecular, morphological and ecological data. To rectify this situation, we developed a novel rearing, imaging, and DNA extraction protocol that maximises retrieval of molecular and morpho-ecological data layers from single larval specimens. Through the design of new primers and a careful evaluation of best practices, we pave the road for finally unravelling the evolutionary history of this enigmatic group of animals. (Image credit: J. Olesen.)

Ninetinae comprises small spiders largely restricted to dry habitats. We studied the ultrastructure, distribution, species limits and karyotype of Papiamenta. The type species P. levii (Gertsch, 1982) may include more than one species but COI and morphology suggest conflicting clade limits. Sperm ultrastructure and gene sequences suggest a close relationship with North American genera, whereas the sex chromosome system closely resembles that of South American genera. Papiamenta is likely an ancient West Indian element of the Leeward Antilles fauna. (Photograph by B. A. Huber.)

Velvet worms are soft-bodied organisms, where crypticity and habitat complexity have created poor taxonomic delineations. This study aims to contribute to the taxonomic revisions through the identification of an undescribed ancient novel lineage living in sympatry, at the Riviersonderend Mountains at Oubos, with the known Peripatopsis lawrencei. In this study, we discovered a new velvet worm species, P. aureus sp. nov., and this is described in this paper. (Photograph by Prof. M. D. Picker.)

We characterise the biodiversity of the taxonomically entangled krill genus Hansarsia in the deep Atlantic by applying an integrative approach. Molecular and morphological analyses suggest at least six species of Hansarsia instead of the currently recognised four. We describe one new species and wait for males to describe the second one. The results confirm ongoing diversification of the Atlantic krill and show an unusual trend in the evolution of euphausiids, in which visual recognition enhances tactile interaction during mating. (Image credit: D. Kulagin.)

Freshwater leeches of the genus Torix Blanchard, 1893 in Japan have considerable morphological variation, leading to taxonomic confusion. In this study, we revisit the taxonomic accounts of T. orientalis (Oka, 1925) and T. tagoi (Oka, 1925) to clarify the diagnostic characteristics for the three Torix species in Japan. Our morphological and molecular phylogenetic analyses demonstrated that the Japanese Torix species are indistinguishable. We therefore conclude that the three Torix species should be synonymised and treated as a single species. (Image credit: Chiaki Kambayashi.)