Melanella martarum sp. nov. (Gastropoda: Eulimidae): the first parasitic deep-sea snail reported for the Salas & Gomez Ridge.

Eulimidae is a highly diverse family of gastropods that are often parasites of echinoderms. They are cosmopolitan and live from the intertidal to great depths. Despite its wide geographic and bathymetric distribution, no species of Eulimidae have been reported for the Salas & Gómez Ridge to date. In this study, we describe Melanella martarum sp. nov., which was collected during the EPIC oceanographic cruise onboard RV Mirai (JAMSTEC, Japan) in 2019. Seven specimens were collected with a modified Agassiz trawl on the summit of seamount "Pearl" (Zhemchuznaya) in the Salas & Gómez Ridge (25.59°S, 89.13°W) at 545 m depth. The morphology of M. martarum sp. nov. was compared with other Melanella species reported for the area, including Chile and Rapa Nui. DNA was extracted and partial sequences of the mitochondrial genes Cytochrome Oxidase 1 (COI) and 16S rDNA, and the nuclear gene Histone 3 (H3) were sequenced. Melanella martarum sp. nov. has morphological characteristics that separate it from other species of Melanella, such as the thickness and color of the shell, and the shape of the protoconch. In addition, M. martarum sp. nov. was genetically differentiated from other Melanella spp. sequences (uncorrected p distances from 18,1-8.6% in mitochondrial COI and 16S rDNA to 3% in nuclear H3 sequences). Although there is not much molecular data available for Eulimidae, the phylogenetic analysis confirms the results obtained by morphology, placing the species found on the Salas & Gómez Ridge within the genus Melanella. The current study advances the understanding of the poorly known benthic fauna found on seamounts in the easternmost part of the Sala & Gómez ridge, a location distinguished by a high level of endemism.

Revision of the deep-sea Eulimidae (Gastropoda, Caenogastropoda) from off Northeast Brazil.

The present study reviews the taxonomy of the marine gastropods belonging to the family Eulimidae Philippi, 1853 from the continental slope off Northeast Brazil. The genera Abyssoaclis Barros, Mello, Barros, Lima, Santos, Cabral Padovan, 2003 and Aclis Lovén, 1846 were not treated here. A total of 20 taxa were identified in this region, excluding Eulima hebes Watson, 1883, a species with a doubtful classification in Eulimidae. The species were assigned to the following genera: Costaclis Bartsch, 1947, Eulima Risso, 1826, Fusceulima Laseron, 1955, Melanella Bowdich, 1822, Ophieulima Warén Sibuet, 1981, Sticteulima Laseron, 1955, Thaleia Warén, 1979, and Umbilibalcis Bouchet Warén, 1986. The genera Sticteulima, Ophieulima and Umbilibalcis are reported for the first time in the southwestern Atlantic. Four species represent new records for the southwestern Atlantic. A redescription of the shell morphology is provided for: Costaclis egregia (Dall, 1889b), Melanella doederleini (Brusina, 1886), and Umbilibalcis lata (Dall, 1889b). Additional information to the original description are reported for other species. Melanella sarissa is considered as a synonym of Melanella cinca Dall, 1927. Six new species are described: Eulima cracentis sp. nov., Melanella paraabida sp. nov., M. adiastalta sp. nov., M. anapetes sp. nov., Sticteulima cabrali sp. nov. and S. canopusensis sp. nov. Lectotypes are designated for: Costaclis hyalina, C. egregia, Eulima ephamilla (Watson, 1883), E. psila and E. (?) hebes. Eulima sp. 1, Melanella sp. 1 and Melanella sp. 2 are potential new species, but the scarcity of material precludes a formal description at this moment.