Melanella doederleini ( Brusina, 1886 )

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 : 472-474

Melanella doederleini ( Brusina, 1886)

( Figure 11 A–I)

Eulima stalioi auct. non Brusina, 1869: Jeffreys (1884: 368, plate 28, figure 3).

Eulima doederleini Brusina, 1886: 214 .

Melanella doederleini ( Brusina, 1886) : Bouchet & Warén (1986: 382, figs. 902–903); Utrilla et al. (2020: 15, figure 4A–D).

Type material. Lectotype ( Bouchet & Warén 1986) NHMUK 1979229 ( Figure 11A, B ) ; Paralectotypes NHMUK 1885.11.5.2027–2028 [2 dd], USNM 131144 [1 dd] (not located) .

Type locality. Southwest of Cadiz , PORCUPINE 1870 stn. 30 (36°15′N 06°52′O, 706 m), coll. H.M.S. Porcupine.

Material examined. Lectotype; paralectotypes NHMUK 1885.11.5.2027–2028; Brazil: Off Ceará, RE-VIZEE Nordeste (03°30′51″S 37°59′28″O, 384 m, coll. RV Natureza, 07/xi/2001): MNRJ 35277 † [2 dd]; Off Pernambuco, REVIZEE Nordeste (08°46′00″S 34°44′00″O, 690 m), coll. RV Natureza, 18/xi/2000): MNRJ 35208 † [4 dd]; Espírito Santo: REVIZEE-Central V stn. 25A (19°35′28″S 38°45′28″W, 230 m), coll. Supply Boat Astro Garoupa, 28/vi/2001: IBUFRJ † 19719 [1 dd].

Redescription (Lectotype). Shell conical, slightly curved at the apex, reaching about 3.6 mm long, 1.3 mm wide. Larval shell vitreous or whitish, almost cylindrical, with about 3.0 whorls; smooth, transition to teleoconch marked by an almost indistinct incremental scar. Teleoconch with about 7.0 whorls, flat outline; suture almost indistinct, sloping slowly; subsutural zone about 15% of the whorl height; surface smooth; incremental scars slightly demarcated, intervals close to 1.0 whorl. Last whorl about 50% of the shell length; base rounded. Aperture short, pear shaped, acute posteriorly and rounded anteriorly; outer lip thin, opisthocline, sinuous, slightly retracting near the suture and projecting in the uppermost third; inner lip sinuous, sloping, reflected, well demarcated. Not umbilicate. Shell vitreous, colorless.

Measurements. Lectotype NHMUK 1979229, 10 whorls, SL= 3.6 mm; BWL= 1.7 mm; AL= 1.0 mm; SW= 1.3 mm; AW= 0.7 mm. MNRJ 35208†, 10 whorls, SL= 3.6 mm; BWL= 1.8 mm; AL= 1.0 mm; SW= 1.3 mm; AW= 0.7 mm.

Remarks. This species has a slightly curved apex and a short and wide aperture; the placement in Melanella is more suitable than the original combination in Eulima . Brusina (1886) and Bouchet & Warén (1986) did not provide a detailed description of the species, therefore we redescribe the shell morphology of the lectotype here. We can add that the specimens from Brazil have a protoconch of 2.8 whorls, 280 μm wide and 250 μm in height.

Melanella doederleini is a very conspicuous species. Shells collected in the West Atlantic are indistinguishable from the lectotype of M. doederleini (NHMUK 1979220; Figure 11A, B ) and from the shells recorded by Utrilla et al. (2020: figure 4A–D) from the Gulf of Cádiz. A small variation is present in the outline of the base, which is more truncated in the lectotype ( Figure 11A ), while it is more rounded in shells from Brazil ( Figure 11C, D ) and in the shells figured by Utrilla et al. (2020). The geographic distribution of M. doederleini is extended by about 7,000 km (from type locality to the coast of Espírito Santo, Southeast Brazil). Hoffman & Freiwald (2020) recorded a few empty shells of “ Melanella cf. doederleini ” from the Azorean seamounts; a confirmed identification can fill part of the wide distributional gap.

Bouchet & Warén (1986) noted that M. doederleini is a possible junior synonym of Melanella altavillensis ( Seguenza, 1876) , but highlighted a small difference in the protoconch of both species. We add that M. doederleini is relatively smaller in length but wider in comparison to the syntype of M. altavillensis figured by Bouchet & Warén (1986: figs. 904–905) and to the shells figured by Landau et al. (2006: plate 19, figure 2A–B). Melanella altavillensis is known only from fossils, while M. doederleini was considered to belong to the biocenosis in the Gulf of Cadiz, with representatives in the taxocoenosis and thanatocoenosis ( Utrilla et al. 2020).

Melanella doederleini resembles Eulima chyta Watson, 1883 ( Figure 11J ), only from its type locality in Ascension Island, but it is larger (MNRJ 35208†, 10 whorls, SL= 3.6 mm vs. syntype of E. chyta NHMUK 1887.2.9.1604, 9 whorls, SL= 2.1 mm), has a higher spire angle, thinner outer lip and by the slightly curved spire as a consequence of the position of the incremental scars. In the syntype of E. chyta ( Figure 11J ) the incremental scars are not clearly visible. Further studies and more samples of both taxa may help clarify the status of these species.

Geographical distribution. Eastern Atlantic: Spain: Southwest of Cadiz ( Bouchet & Warén, 1986); Azorean seamounts ( Hoffman & Freiwald 2020). Western Atlantic: Brazil: Ceará, Pernambuco and Espírito Santo (present study).

Bathymetric distribution. From 230 m to 706 m.

Figures

FIGURE 11. A–I. Melanella doederleini (Brusina, 1886): A, B. Lectotype of Eulima doederleini Brusina, 1886, NHMUK 1979229; C, D, F, H, I. MNRJ 35208; E, G. MNRJ 35211. J. Eulima chyta Watson, 1883: syntype, NHMUK 1887.2.9.1604. H. Detail of protoconch, frontal view. I. Detail of protoconch, apical view. Scale bars: A–E= 1.0 mm; F, G= 200 µm; H, I= 100 µm. Credits: A, B, courtesy of NHMUK.