Ophieulima minima ( Dall, 1927 )

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 : 485-487

Ophieulima minima ( Dall, 1927)

( Figure 19 A–G)

Stilifer minima Dall, 1927: 73 .

Ophieulima minima: Warén & Sibuet (1981: 381 , figs. 1–5); Hoffman et al. (2011: 34, figs. 45–46); Romani et al. (2014: 1, figure 1A–F); Hoffman & Freiwald (2020: 89–90).

Type material. Holotype USNM 108039 ( Figure 19A, G ).

Type locality. USA: Off Georgia, USFC stn. 2668 (30°58′30″N 79°38′30″W, 538 m), 05/v/1886 .

Material examined. Type material; Brazil: Alagoas: (09°20′S 34°59′W, 452 m), 18/xii/2001: MNRJ 35223 † [1 dd] .

Measurements. Holotype USNM 108039, ~6 whorls, SL= 2.3 mm; BWL= 1.6 mm; AL= 1.0 mm; SW= 1.2 mm; AW= 0.8 mm. MNRJ 35223†, ~6 whorls, SL= 1.9 mm; BWL= 1.3 mm; AL= 0.9 mm; SW= 1.0 mm; AW= 0.6 mm.

Remarks. Dall (1927) recorded four specimens in the original description. Warén & Sibuet (1981) described two paratypes under the same catalog number as the holotype. No other specimen than the holotype ( Figure 19A, G ) was found in the USNM and the status of these other shells is unknown or they are presumed lost (E. Strong, personal communication). Warén & Sibuet (1981: 384) redescribed the species and noted that the variation in shape of the type specimens is great and that the identification of the material by them is questionable, because the northeast Atlantic specimens studied are even broader than the types. Bouchet & Warén (1986: 348) also considered the shell morphology of the species quite variable, with an evident sexual dimorphism (males are half the size of females).

Beside the variation in size and shape correlated with the sexual dimorphism, a variation in shell sculpture can also be observed. Warén & Sibuet (1981: 384) commented that none of the types shows the spiral striation that occurs in some well-preserved specimens from the Northeast Atlantic examined by them. The latter authors described this spiral sculpture as irregular, extremely fine scratch-like striae present in some small areas of the shell that are less corroded in such specimens. The examination of SEM images of the holotype of Ophieulima minima (USNM 108039) ( Figure 19A, G ) has not revealed the presence of the spiral scratch-like striae, but only the axial growth lines. Romani et al. (2014) reported O. minima from the Mediterranean and did not observe the spiral sculpture in very fresh shells, with dried specimens.

The single shell from Brazil agrees well with the paratypes illustrated by Bouchet & Warén (1986: figs. 827– 830) in the general shape ( Figure 19B, C ), number of whorls of the larval shell (=3.0 whorls) ( Figure 19G ) and the axial sculpture of faint growth lines ( Figure 19C, D ). The holotype of Ophieulima minima presents a protoconch with about 2.6 whorls and 195 µm in diameter ( Figure 19G ) and the shell from Brazil has 3.0 protoconch whorls, 210 µm wide ( Figure 19F ). The teleoconch of the holotype of O. minima and the shell from Brazil have about three whorls, but the former reaches 2.8 mm long and the latter reaches 1.9 mm long, which represents about 65% of the shell length of the holotype. The shell from Brazil is fairly corroded, as can be seen from the several pits in the shell surface ( Figure 19F ) and spiral sculpture was not observed.

Even with these small differences in size, shape, and sculpture, the shell from Brazil is identified as Ophieulima minima . This represents the southernmost record of O. minima . It is possible that further material and other techniques will uncover more species of Ophieulima than currently expected in the whole Atlantic.

Geographical distribution. Northeastern Atlantic: South Iceland to South of the Bay of Biscay ( Bouchet & Warén 1986); Mediterranean ( Romani et al. 2014); Azorean seamounts ( Hoffman & Freiwald 2020). Western Atlantic: USA: Georgia ( Dall 1927); Brazil: Alagoas (present study).

Bathymetric distribution. From 452 m to 2100 m.

Figures

FIGURE 19. A–G. Ophieulima minima (Dall, 1927). A, G. Holotype of Stilifer minima Dall, 1927, USNM 108039. B–F. MNRJ 35223. E. Detail of protoconch, frontal view. F, G. Detail of protoconch, apical view. Scale bars: A–D= 1.0 mm; E= 100 µm; F= 75 µm; G= 50 µm. Credits: A, G, courtesy of USNM.