Melanella paraabida, Souza & Pimenta & Barros, 2021

Souza, Leonardo Santos De, Pimenta, Alexandre Dias & Barros, José Carlos Nascimento De, 2021, Revision of the deep-sea Eulimidae (Gastropoda, Caenogastropoda) from off Northeast Brazil, Zootaxa 4927 (4), pp. 451-504 : 476-479

Melanella paraabida sp. nov.

urn:lsid:zoobank.org:act:8D796B06-259E-445F-8C87-B6C4FF5BE506

( Figure 13 A–H)

Type material. Holotype MNRJ 35262 † ( Figure 13 A–H).

Type locality. Brazil: Off Pernambuco, REVIZEE Nordeste (08°42′06″S 34°44′06″W, 465 m), coll. RV Natureza, 25/iii/2000 .

Etymology. Named after its similarity to Melanella abida Dall, 1927 .

Description (Holotype). Shell conical, curved, reaching about 3.4 mm long, 1.1 mm wide. Larval shell whitish, conical, consists of 2.5 whorls, 220 µm in wide, smooth, transition to teleoconch marked by distinct incremental scar. Teleoconch with about 7.5 whorls, flat outline; suture slightly demarcated, almost straight; subsutural zone indistinct; surface sculptured by axial lines, intervals about 25 µm in the penultimate whorl; incremental scars well demarcated, appearing at intervals of about 1.0 whorl in the last three whorls, stepped. Last whorl about 45% of the shell length; base rounded. Aperture short, pear shaped, acute posteriorly and rounded anteriorly; outer lip relatively thick, opisthocline, sinuous, slightly retracting near the suture and slightly projecting in the uppermost third; inner lip sinuous, sloping, reflected and well demarcated. Not umbilicate. Shell vitreous, colorless.

Measurements. Holotype MNRJ 35262†, 10 whorls, SL= 3.4 mm; BWL= 1.5 mm; AL= 0.8 mm; SW= 1.1 mm; AW= 0.5 mm.

Remarks. Despite having only a single shell, we describe Melanella paraabida based on the combination of consistent shell features that enable us to discriminate this species from the other eulimids known to the Atlantic. The holotype was destroyed during the fire in the MNRJ.

Melanella paraabida sp. nov. closely resembles M. abida Dall, 1927 ( Figure 14A, B ), known only from off

Georgia, USA. Dall (1927) cited the type locality of M. abida as “off Fernandina, Florida ” but the label of the holo-type (USNM 108030) clearly indicates “RV Albatross stn. 2668”, thus the correct locality is off Georgia. Melanella corrida Dall, 1927 ( Figure 14 C–F), from the same locality, is a synonym of M. abida (MolluscaBase Eds. 2020b) . Melanella paraabida sp. nov. can be distinguished from M. abida mainly by the presence of microsculpture on the teleoconch ( Figure 13D ) and the less protruding outer lip. Additionally, the protoconch of M. paraabida sp. nov. has a smaller number of whorls and diameter. Melanella paraabida sp. nov. has a protoconch 210 µm wide with 2.5 whorls, while the holotype of M. corrida (USNM 108376) ( Figure 14F ) has a protoconch 260 µm wide with 3.5 whorls.

Melanella paraabida sp. nov. resembles M. orphanensis Clarke, 1974 ( Figure 17K ), from the North Atlantic, and M. scarifata Gofas & Rueda, 2014 ( Gofas et al. 2014), from the Alboran and Mediterranean sea, by the teleoconch sculpture. Melanella paraabida sp. nov. differs from M. orphanensis by the narrower apex ( Figure 13G ), which is dome shaped in the latter ( Figure 17K ). Melanella paraabida sp. nov. differs from M. scarifata by the smaller dimensions of the protoconch (2.5 whorls, 210 µm wide vs. 3.5 whorls, 350 µm wide in M. scarifata ) and the less protruding outer lip ( Figure 13F ).

Melanella paraabida sp. nov. resembles Melanella spiridioni ( Dautzenberg & Fischer, 1896) , from Northeast Atlantic and Mediterranean, by the curved spire but differs by the presence of microsculpture of axial lines.

Geographical distribution. Only known from the type locality.

Bathymetric distribution. 465 m.

Figures

FIGURE 13. A–H. Melanella paraabida sp. nov.: holotype, MNRJ 35262. D. Detail of the teleoconch surface. G. Detail of protoconch, frontal view. H. Detail of protoconch, apical view. Scale bars: A–C= 1.0 mm; D= 100 µm. E, F= 200 µm; G, H= 50 µm.

FIGURE 14. A–F. Melanella abida Dall, 1927: A. Holotype of Melanella abida Dall, 1927, USNM 108030. B, F. Holotype of Melanella corrida Dall, 1927, USNM 108376. C–E. Paratypes of M. corrida, USNM 108376. F. Detail of protoconch, apical view. Scale bars: A–E= 1.0 mm; F= 75 µm. Credits: A, B, F, courtesy of USNM.

FIGURE 17. A–G. Melanella sp. 1: MNRJ 35251. H–J. Melanella jeffreysi: lectotype of Eulima jeffreysi Tryon, 1886, USNM 133126. K. Melanella orphanensis Clarke, 1974: holotype, CMNML 66345. D, J. Detail of the teleoconch surface. G. Detail of protoconch, apical view. Scale bars: A–C, H, I, K= 1.0 mm. D= 50 µm. E, F, J= 200 µm; G= 100 µm. Credits: J, courtesy of USNM; K, courtesy of J-M Gagnon (CMNML).