Fassio G., Stefani M., Russini V., Buge B., Bouchet P., Treneman N., Malaquias M.A.E., Schiaparelli S., Modica M.V. & Oliverio M. 2022. Neither slugs nor snails: a molecular reappraisal of the gastropod family Velutinidae. Zoological Journal of the Linnean Society 197(4): 924-964. DOI:10.1093/zoolinnean/zlac091 ???msg.biblio.abstract.label???[+][-]
Abstract
The systematics of the marine mollusc family Velutinidae has long been neglected by taxonomists, mainly because their often internal and fragile shells offer no morphological characters. Velutinids are usually undersampled owing to their cryptic mantle coloration on the solitary, social or colonial ascidians on which they feed and lay eggs. In this study, we address the worldwide diversity and phylogeny of Velutinidae based on the largest molecular dataset (313 specimens) to date, accounting for > 50% of the currently accepted genera, coupled with morphological and ecological data. Velutinids emerge as a diverse group, encompassing four independent subfamily-level lineages, two of which are newly described herein: Marseniopsinae subfam. nov. and Hainotinae subfam. nov. High diversity was found at genus and species levels, with two newly described genera (Variolipallium gen. nov. and Pacifica gen. nov.) and ≥ 86 species in the assayed dataset, 58 of which are new to science (67%). Velutinidae show a remarkable morphological plasticity in shell morphology, mantle extension and chromatic patterns. This variability is likely to be the result of different selective forces, including habitat, depth and trophic interactions.
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IM (Mollusques)
Wong M.K. & Chen W.J. 2024. Exploring the phylogeny and depth evolution of cusk eels and their relatives (Ophidiiformes: Ophidioidei). Molecular Phylogenetics and Evolution 199: 108164. DOI:10.1016/j.ympev.2024.108164 ???msg.biblio.abstract.label???[+][-]
With 289 known species in 51 genera, the ophidiiform family Ophidiidae together with their relatives from the Carapidae (36 species in eight genera) of the same suborder Ophidioidei dominate the deep sea, but some occur also in shallow water habitats. Despite their high species diversity in the deep sea and wide bathymetric distributions, their phylogenetic relationships and evolution remain unexplored due in part to sampling difficulties. Thanks to the biodiversity exploratory program entitled “Tropical Deep-Sea Benthos” and joint efforts between Taiwan and French teams for sampling from different localities across the Indo-West Pacific over the last two decades, we are able to compile comprehensive datasets for investigations. In this study, 59 samples representing 36 of 59 known ophidioid genera are selected and used to construct a multi-gene dataset to infer the phylogenetic relationships of ophidioid fishes and their relatives. Our results reveal that the Ophidiidae forms a paraphyletic group with respect to the Carapidae. The four main clades of Ophidioidei resolved are the (1) clade comprising species from the subfamily Brotulinae; (2) clade that includes species in the genera Acanthonus and Xyelacyba; (3) clade grouping Hypopleuron caninum with species from the family Carapidae; and (4) clade containing the species in the subfamily Brotulotaenilinae, Neobythitinae (in part), and Ophidiinae. Accordingly, we suggest the
following new revisions based on our results and proposed morphological diagnoses. The subfamily Brotulinae
should be elevated to the family level. The genera Xyelacyba and probably Tauredophidium (unsampled in this
study) should be included in the newly established family Acanthonidae with Acanthonus. The families Carapidae
and Ophidiidae are re-defined. Our time-calibrated phylogenetic and ancestral depth reconstructions enable us to
clarify the evolutionary history of ophidiiform fishes and infer past patterns of species distributions at different
depths. While Ophidiiformes is inferred to have originated in shallow waters around 96.25 million years ago
(Mya), the common ancestor to the Ophidioidei is inferred to have invaded the deep sea around 90.22 Mya, the
dates coinciding with the global anoxic event of the OAE2. The observed bathymetric distribution patterns in
Ophidioidei most likely point to the mesopelagic zone as the center of origin and diversification. This was followed by multiple events of depth transitions or range expansions towards either shallower waters or greater depth zones, which were likely triggered by past climate changes during the Paleogene-Neogene.