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

Abstract

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.

First occurrence of ophiuroid-parasitic genus Ophieulima (Mollusca: Gastropoda: Eulimidae) in the North Pacific Ocean

“…The new species has a protoconch of 3.5 whorls, which is more coiled than that of the type species (2.7–3 whorls according to previous studies) and less than O. fuscoapicata (3.9 whorls). However, it should be noted that the protoconch of O. minima apparently has up to 3.7 whorls (see Souza et al ., 2021: figure 19F, G). As in the present new species, one or two distinct scars, which might be confused with the demarcation line between the protoconch and teleoconch, exist on the protoconch at 0.8–1.2 whorls from the demarcation line.…”

“…as the third extant species of the genus. Given a few previous occurrence records (Warén, 1981; Warén and Sibuet, 1981; Bouchet and Warén, 1986; Hoffman et al ., 2011; Romani et al ., 2014; O'Reilly, 2016; Souza et al ., 2021) and low prevalence (1.4% for O. minima ; see O'Reilly, 2016), the species of Ophieulima are rare, while the genus possibly has a global distribution. Their minute sizes and deep-sea habitats may have also been making it difficult to discover Ophieulima species.…”

“…Its shell is characterized by (1) a conical shape with convex teleoconch whorls, (2) a length of up to 3 mm, (3) many fine growth lines and up to two strong growth pause scars on the teleoconch, (4) a solid and twisted columella, (5) a sculpture of oblique incised line segments, and (6) a brownish transparent protoconch with ca. 3 whorls (Warén and Sibuet, 1981;Romani et al, 2014;Souza et al, 2021; but see Remarks below). Other notable characters of the species include the lack of pigmented eyes and the radula (a tongue-like feeding apparatus of the Mollusca), presence of the operculum, separate sexes, and sexual dimorphism with the female of 2.5-3 mm in shell length and the male of 1-1.5 mm (Warén and Sibuet, 1981; but see O'Reilly, 2016: figure 24 for the presence of pigmented eyes).…”

“…Only two named and one undescribed species have been reported from bathyal depths as extant taxa (Warén, 1981; Warén and Sibuet, 1981). The type species, Ophieulima minima (Dall, 1927), inhabits the Atlantic Ocean and Mediterranean, 452–2140 m deep, parasitizing Ophiactis abyssicola (M. Sars, 1861) of Ophiactidae (Warén and Sibuet, 1981; Bouchet and Warén, 1986; Hoffman et al ., 2011; Romani et al ., 2014; Souza et al ., 2021). Its shell is characterized by (1) a conical shape with convex teleoconch whorls, (2) a length of up to 3 mm, (3) many fine growth lines and up to two strong growth pause scars on the teleoconch, (4) a solid and twisted columella, (5) a sculpture of oblique incised line segments, and (6) a brownish transparent protoconch with ca .…”