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

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Melanella paraabida

sp. nov.

Melanella paraabida sp. nov.

( Figure 13 View FIGURE 13 A–H)

Type material. Holotype MNRJ 35262 View Materials † ( Figure 13 View 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 GoogleMaps .

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 View FIGURE 14 ), 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 View 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 View FIGURE 13 ) 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 View FIGURE 14 ) has a protoconch 260 µm wide with 3.5 whorls.

Melanella paraabida sp. nov. resembles M. orphanensis Clarke, 1974 ( Figure 17K View FIGURE 17 ), 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 View FIGURE 13 ), which is dome shaped in the latter ( Figure 17K View FIGURE 17 ). 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 View FIGURE 13 ).

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.