Strobiligera cf. delicata Fernandes & Pimenta, 2014

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 : 34-36

Strobiligera cf. delicata Fernandes & Pimenta, 2014

Fig. 17C–H

Strobiligera delicata Fernandes & Pimenta, 2014: 166 , fig. 1b–k.

Type material

Holotype

BRAZIL • sh; off Espírito Santo State; 19°36′ S, 38°53′ W; depth 640 m; MNHN IM-2000-27528.

Paratypes

See Fernandes & Pimenta (2014).

Material examined

GUADELOUPE (Karubenthos 2 expedition) • 1 sh; stn DW4556; MNHN • 1 sh; stn DW4577; MNHN • 1 spec. stored dry; stn DW4635; MNHN .

Emended description

Shell sinistral, conical-fusiform, single complete shell up to 7.0 mm long (incomplete shells up to 8.9 mm long) and 1.5 mm wide, length/width ratio 4.7, apical angle of early whorls 18–20°; one shell with a distinct change in width on 13 th teleoconch whorl, becoming broader. Protoconch multispiral, 3.5– 4.0 whorls, 0.50–0.53 mm long, 0.34–0.37 mm wide; first whorl dome-shaped, with minute granules; subsequent whorls with two spiral cords, situated at 35% and 68% of whorl height; incomplete axial ribs (~33 ribs per whorl), with a smooth spiral zone above adapical spiral cord; abrupt transition to teleoconch. Teleoconch with up to 17 whorls (incomplete); three main spiral cords, with median and abapical cords continuous with those of protoconch; adapical spiral cord initially narrow, but gradually enlarging and reaching nearly same size as other cords between 11 th and 13 th whorls; shallow suture, almost indistinct, with a very narrow, smooth sutural cord; 18–19 orthocline axial ribs on 14 th whorl; medium-sized to moderately large, nearly rounded to slightly elliptical nodules; wide, smooth subperipheral cord, two smooth basal cords, adapical one prominent and close to subperipheral one, abapical cord narrow and more distant; no evident supranumerical cords; elliptical aperture, 1.0 mm long, 0.69 mm wide, length/ width ratio 1.5; open, very short anterior canal, 0.14 mm long, 0.20 mm wide, length/width ratio 0.7. Protoconch light brown, teleoconch white to dirty-white.

Remarks

Shells of S. cf. delicata from Guadeloupe are very similar to the type material from SE Brazil, and their planktotrophic development could allow such a wide geographic range. The single adult shell from Guadeloupe is 7.0 mm long and incomplete shells reach up to 8.9 mm, contrasting with adult shells from Brazil, reaching only 5.8 mm. This difference in length might be related to the later development of the adapical spiral cord on the teleoconch in shells from Guadeloupe, reaching nearly the same size as other cords between the 11 th –13 th whorls vs the eighth–tenth whorl in the type material. More adult shells from Guadeloupe are required in order to evaluate the importance of these differences.

The most similar species to S. cf. delicata in Guadeloupe is S. cf. georgiana , which has a much reduced adapical spiral cord, fewer axial ribs on the teleoconch, a slightly opisthocline orientation of the axial ribs (vs orthocline in S. cf. delicata ) and a larger and more conical shell. These differences were already pointed out by Fernandes & Pimenta (2014) when they compared the types of both species.

One atypical shell of S. cf. delicata has a distinct change in width on the 13 th teleoconch whorl, becoming broader ( Fig. 17D ). This is also observed in S. torticula ( Rolán & Fernández-Garcés 2008; Fernandes & Pimenta 2015b), which in contrast is much larger (incomplete shell reaching up to 25.0 mm in length – Rolán & Fernández-Garcés 2008) than S. cf. delicata . In addition, the protoconch of S. torticula has almost five whorls and it is 0.64 mm long and 0.45 mm wide ( Fernandes & Pimenta 2015b) vs 3.5–4.0 whorls, 0.50–0.53 mm long and 0.34–0.37 mm wide in S. cf. delicata .

Geographic distribution

Guadeloupe (this study); Brazil: off Espírito Santo and Rio de Janeiro ( Fernandes & Pimenta 2014).

Bathymetric distribution

Empty shells previously known from 607–940 m ( Fernandes & Pimenta 2014). This study: 358–428 m (empty shells), 265–268 m (live specimen).

Figures

Fig. 17. A–B. Strobiligera cf.georgiana (Dall, 1927), MNHN, stnDW4550, 15.1 mm. C–H. Strobiligera cf. delicata Fernandes & Pimenta, 2014. C. MNHN, stn DW4556, 8.9 mm. D. MNHN, stn DW4577, 8.9 mm. E–H. MNHN, stn DW4635, 7.0 mm. Scale bars: A, C–E = 1 mm; B, F–H = 500 µm.