Pleurotomella perpauxilla Watson 1881

Pleurotomella perpauxilla (Watson, 1881)

(Figs. 44–46)

Pleurotoma (Defrancia) perpauxilla Watson, 1881: 468.

Clathurella perpauxilla (Watson, 1881): Watson (1886: 359, pl. XXII, fig. 7).

Type material: Syntypes BMHN 1887.2.9.1109

Type locality: West Indies, North of Culebra Island (18º 38’ 30”N, 65º 05’ 30”W), 713 m.

Material examined: Type material and 18966 [2] OP I # 47; 18967 [1] OP I # 53; 18968 [1] OP I # 58; 18969 [1] OP I # 63; 18970 [1] OP I # 75; 18971 [1] OP I # 83; 18972 [4] OP I # 44; 18973 [2] OP II # 47; 18974 [1] OP II # 49; 18975 [1] OP II # 53; 18976 [4] OP II # 59; 18977 [1] OP II # 61; 18978 [1] OP II # 63; 18979 [1] OP II # 78; 15428 [3] OP I # 49; 17269 [2] OP II # 74.

Description: Shell conical, white, up to 5.34 mm long. Protoconch with about 3.5 whorls. Protoconch 1 with rows of tiny crosses. Protoconch 2 with diagonal cancellation on the lower 2/3 of the whorls and axial riblets on the upper third. Clear-cut proto-teleoconch boundary. Teleoconch with a subsutural slightly concave area sculptured with several axial riblets and a spiral thread. Below this area, about 10 large oblique axial ribs (on the third whorl) crossed by two spiral cords. Shell surface granulose. Suture very shallow. Base elongated, ornamented with about 12 spiral cords. Inner lip reflected over parietal wall. Outer lip thin. Anterior siphonal canal relatively short and narrow. Aperture elliptical.

Geographic distribution: Northwest Atlantic: West Indies (Watson, 1881; Watson, 1886). Southwest Atlantic: Campos Basin, Rio de Janeiro (this paper). Bathymetry: 713 m (Watson, 1881)– 1950 m (this paper).

Discussion: Our material is almost identical to the type material of P. perpauxilla Watson, 1881 (fig. 46). Dall (1889: 116) synonymized this species with Mangilia ? elusiva Dall, 1881 (figured in Dall, 1889, pl. XII, fig. 7). Though we have not examined the type material of M. elusiva, the original illustration exhibits clear differences from P. perpauxilla (fig. 43). Dall’s specimen has a larger profile, more angled shoulder and a shorter body whorl. So, until the type material of M. elusiva is directly examined we cannot agree with this synonymy.

Pleurotomella perpauxilla is reported for the first time in South Atlantic waters (21–22ºS). It was previously known to occur in the Caribbean (18ºN). Its bathymetric range is also increased. The only depth previously reported for this species was 713 m (Watson, 1881) and it has now been found at depths from 722 to 1950 m.