Eulima hebes Risso 1826

Eulima? hebes Watson, 1883

(Figure 25 A–K)

Eulima hebes Watson, 1883: 127–128. Watson (1886: 521, plate 37, figure 6a–b).

Melanella hebes (Watson, 1883): Lange-de-Morretes (1949: 82); Rios (1994: 104, plate 34, figure 428 [reproduced from original illustration]); Barros et al. (2001: figure 5a); Rios (2009: 192, figure 471 [reproduced from original illustration]).

Balcis (?) hebes (Watson, 1883): Rios (1975: 61, plate 16, figure 240 [reproduced from original illustration]); Rios (1955: 54, plate 20, figure 243 [reproduced from original illustration]).

Zebina hebes (Watson, 1883): MolluscaBase Eds. (2020f).

Type material. Lectotype (herein designated) NHMUK 1887.2.9.1618 (Figure 25A); paralectotypes (herein designated) NHMUK 1887.2.9.1619–1621 [3 dd] (Figure 25 B–D), from the type locality; paralectotype NMW 1955.158.26256 (Figure 25E), from the type locality.

Type locality. Brazil: off Pernambuco, Challenger stn. 122.

Material examined. Type material; Brazil: Pernambuco: (08°42′06″S 34°44′06″W, 465 m) coll. RV Natureza, 25/iii/2000: MNRJ 35196 † [6 dd]; (08°46′00″S 34°44′00″W, 690 m) coll. RV Natureza, 18/xi/2000: MNRJ 35214 † [1 dd], MORG 49210 † [6 dd], MORG 50046 † [20 dd].

Measurements. Lectotype NHMUK 1887.2.9.1618, 5 whorls (aperture partially broken), SL= 3.7 mm; BWL= 2.2 mm; AL= 1.4 mm; SW= 1.8 mm; AW= 0.9 mm. MNRJ 33556†, 6 whorls, SL= 5.1 mm; BWL= 3.0 mm; AL= 1.9 mm; SW= 2.3 mm; AW= 1.3 mm.

Remarks. The shell of NHMUK 1887.2.9.1618 is the figured specimen by Watson (1886: plate 37, figure 6) and is here selected as the lectotype (Figure 25A). There are paralectotypes in the NHMUK (Figure 25 B–D) and possibly in the NMW (Figure 25E).

Watson (1883) classified this species in Eulima, but it clearly differs from Eulima sensu stricto by its conical shape with a subtle increase in diameter, well-demarcated sutures and by the wide, obtuse apex. The present species was classified in Melanella by some authors (e.g., Lange-de-Morretes 1949; Rios 1994). The well-demarcated suture and the outline of the outer lip of “ E. hebes ” are not similar to other species of Melanella despite the great conchological variation considered in the latter genus (Bouchet & Warén 1986).

MolluscaBase Eds. (2020f) classified the species in Zebina H. Adams & A. Adams, 1854 (Zebinidae Coan, 1964), but treated the species as a taxon inquirendum, mentioning that “the description strongly suggests that it belongs neither to Eulima, nor to Zebina ”. MolluscaBase Eds. (2020f) argued that based on features described by Watson (1883), as “unequal, close-set, hair-like microscopic lines of growth and faint broader spirals”, and especially the faint broader spirals indicate that it is not a Zebina, but possibly a species of Caelatura s.l. (Barleeiidae Gray, 1857). However, there is no publication reviewing the taxonomy of “ E. hebes ”. Based only on conchological features the systematic position of this species remains unclear, but in fact the species resembles some members of Rissooidea.

No soft parts are available to aid and elucidate the systematic position of “ E. hebes ” and a final decision is postponed, but we figured as many details as possible of the shell morphology to help in further investigations. We keep the original classification of the species here, but we draw attention to the uncertainties of the classification of this species.

Geographical distribution. Brazil: Pernambuco.

Bathymetric distribution. From 465 m to 690 m.