Strobiligera dinea ( Dall, 1927 )

Fernandes, Maurício Romulo, 2024, The deep-sea species of Triphoridae (Gastropoda, Triphoroidea) from Guadeloupe, sampled by the Karubenthos 2 expedition, European Journal of Taxonomy 972, pp. 1-52 : 27-30

Strobiligera dinea ( Dall, 1927)

Figs 13–15

Triphora ( Strobiligera) pompona var. dinea Dall, 1927: 95 .

Triphora ( Strobiligera) dinea – Abbott 1974: 112.

Inella dinea – Rolán & Fernández-Garcés 2008: 126, fig. 19d–i.

Strobiligera dinea – Fernandes & Pimenta 2014: 169; 2019a: 37, figs 3u–v, 21.

Type material

Lectotype USA • sh; off Georgia; USNM 333517. 11 paralectotypes are stored in the same lot.

Material examined

GUADELOUPE ( Karubenthos 2 expedition) • 2 sh; stn DW4536; MNHN • 19 sh; stn DW4549; MNHN • 2 sh, 1 spec. stored dry; stn DW4550; MNHN • 1 sh; stn DW4599; MNHN • 4 sh, 1 spec. stored dry; stn DW4634; MNHN • 1 sh; stn CP4649; MNHN .

Emended description

Shell sinistral, conical-fusiform, a few shells slightly constricted at apex, up to 20.1 mm long (adult shells reach at least 11.1 mm in length), 2.8 mm wide, length/width ratio 5.5–7.0, apical angle of early whorls 11–13°. Protoconch paucispiral, globose, 2.25–3.0 whorls, 0.75–1.25 mm long, 0.70–1.03 mm wide; first whorl smooth, much inflated, sometimes slightly wider (up to 1.1×) than last whorl; second whorl with two smooth spiral cords, situated at 32–42% and 69–72% of last whorl height, abapical cord sometimes slightly more prominent, in addition to a very narrow subsutural cord; gradual transition to teleoconch, from a smooth spiral sculpture to a nodulous one. Teleoconch with up to 21 whorls; three main spiral cords (continuous with those of protoconch), adapical one considerably reduced in initial whorls, but gradually strengthening and sometimes reaching a similar size (never equal) as other cords near body whorl; suture very shallow, almost indistinct, with a narrow sutural cord; 17–20 orthocline to slightly opisthocline axial ribs on 12 th teleoconch whorl; medium-sized, nearly rounded to slightly elliptical nodules; smooth subperipheral cord, with a smooth, very thin basal cord right below it; a weak to distinct supranumerical cord may form between median and abapical spiral cords; nearly rounded to slightly elliptical aperture, 1.16–1.99 mm long, 0.89–1.42 mm wide, length/width ratio 1.2–1.4; anterior canal very short, often open (sometimes partially closed), 0.35–0.41 mm long, 0.41–0.55 mm wide, length/width ratio 0.7–0.9; posterior canal as a minute notch. Shell white.

Remarks

Strobiligera dinea has a distinctive inflated first protoconch whorl. Two other West Atlantic species share this feature: Strobiligera inflata (Watson, 1880) and Strobiligera pompona ( Dall, 1927) . However these two species are distinguished by their reduced adapical spiral cord on the teleoconch. Dall (1927) noted that S. dinea has a less prominent sculpture than S. pompona , but possibly this is because most types are worn; for example, intact shells from Guadeloupe have a prominent teleoconch sculpture.

Shells from Guadeloupe show considerable variation in adult length, protoconch dimensions and the development of the adapical spiral cord. One atypical shell ( Fig. 13C ), with 3.25 protoconch whorls ( 0.57 mm wide only) and a considerably developed adapical spiral cord on the teleoconch, was not included in the description because it may represent a distinct species.

The most similar species to S. dinea from Guadeloupe is S. cf. enopla , which has a less inflated first protoconch whorl, reduced protoconch dimensions ( 0.58–0.70 mm long, 0.53–0.62 mm wide vs 0.75– 1.25 mm long, 0.70–1.03 mm wide in S. dinea from Guadeloupe), and its adapical spiral cord on the teleoconch often develops slower than in S. dinea . However, sometimes it is difficult to distinguish both species.

Geographic distribution

USA: Georgia ( Dall 1927); Guadeloupe (this study); Brazil: off Espírito Santo, Champlain Seamount ( Fernandes & Pimenta 2019a).

Bathymetric distribution

Empty shells previously known from 607–940 m ( Fernandes & Pimenta 2019a). This study: 262–482 m (empty shells), 304–482 m (live specimens).

Figures

Fig. 13. Strobiligera dinea (Dall, 1927). A–B. MNHN, stn CP4649, 12.4 mm. C. MNHN, stn DW4599, 4.7 mm. D–G. MNHN, stn DW4536, 11.4 mm, 9.8 mm.H–K. MNHN, stn DW4549, 11.8 mm, 12.3 mm. Scale bars: A, C–D, F, H, J = 1 mm; B, E, G, I, K = 500 µm.

Fig. 14. Strobiligera dinea (Dall, 1927). A–H. MNHN, stn DW4549, 15.4 mm, 18.6 mm, 20.1 mm, 8.9 mm, 11.1 mm. I–L. MNHN, stn DW4550, 10.4 mm, 12.2 mm. Scale bars: A, C, E, G–I, K = 1 mm; B, D, F, J, L = 500 µm.

Fig. 15. Strobiligera dinea (Dall, 1927).A–B. MNHN, stn DW4550, 7.7 mm.C–F. MNHN, stn DW4634, 14.7 mm, 8.3 mm. G–H. MNHN, stn DW4549. Scale bars: A, C, E = 1 mm; B, D, F–H = 500 µm.