Strobiligera cf. enopla ( 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 : 14-17

Strobiligera cf. enopla ( Dall, 1927)

Figs 7–8

Triphora (Strobiligera) enopla Dall, 1927: 95 .

Triphora (Strobiligera) enopla – Abbott 1974: 112.

Inella enopla – Rolán & Fernández-Garcés 2008: 120, fig. 18a–e.

Strobiligera enopla – Fernandes & Pimenta 2014: 169; 2019a: fig. 3x.

Type material

Lectotype

USA • sh; ‘off Fernandina’ [but coordinates provided by Dall (1927) off Fernandina (Florida) actually match with the state of Georgia]; depth 538 m; USNM 108074. According to the NMNH invertebrate collection website, the original label and the five paralectotypes, which should be stored in the same lot ( Rolán & Fernández-Garcés 2008), are missing.

Material examined

GUADELOUPE (Karubenthos 2 expedition) • 1 sh; stn DW4544; MNHN • 8 sh; stn DW4549; MNHN • 3 sh; stn DW4550; MNHN • 1 spec. stored dry; stn DW4555; MNHN • 1 sh; stn DW4556; MNHN • 2 sh; stn DW4572; MNHN.

Additional material examined (not included in the description)

GUADELOUPE (Karubenthos 2 expedition) • 1 sh; stn DW4555; MNHN.

Emended description

Shell sinistral, conical-fusiform, sometimes with apex constricted, up to 15.3 mm long (adult shells reach at least 9.9 mm in length), 2.2 mm wide, length/width ratio 5.5–7.5, apical angle of early whorls ~10°. Protoconch paucispiral, sub-columnar, 2.25–2.75 whorls, 0.58–0.70 mm long, 0.53–0.62 mm wide; small nucleus rises in an adapical direction and further goes abapical in an oblique descent; first whorl often slightly inflated, with initial portion mainly smooth; two main smooth spiral cords gradually appear, situated at 27–34% and 69–73% of last whorl height, abapical cord slightly to considerably 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 25 narrow whorls; three main spiral cords (continuous to those of protoconch), abapical one often more prominent in initial whorls; median spiral cord soon reaches same size as abapical cord, but adapical spiral cord slowly strengthens along teleoconch, reaching same size as other cords only in 21 th –23 th whorl; suture very shallow, with a smooth sutural cord; 15–18 nearly orthocline to opisthocline axial ribs on 12 th teleoconch whorl; medium-sized, nearly rounded to slightly elliptical nodules; nearly smooth subperipheral cord, with a smooth, very thin basal cord right below it; a weak supranumerical cord may form between median and abapical spiral cords; small, nearly rounded to slightly elliptical aperture, 1.04–1.13 mm long, 0.74–0.88 mm wide, length/width ratio 1.2–1.5; anterior canal very short, open, 0.22–0.29 mm long, 0.23–0.30 mm wide, length/width ratio 0.8–1.2; posterior canal as a small notch, not detached from aperture. Shell white.

Remarks

The lectotype of S. enopla is composed of two fragments which are probably derived from a single shell ( Fernandes & Pimenta 2019a: fig. 3x), nearly matching the ~18 teleoconch whorls counted by Dall (1927). Unfortunately, the paralectotypes illustrated by Rolán & Fernández-Garcés (2008) are currently missing (NMNH invertebrate collection website). Shells of S. cf. enopla from Guadeloupe sometimes have a constricted apex ( Figs 7–8 ), which is also slightly the case in the lectotype. Similarly to the type material ( Rolán & Fernández-Garcés 2008), shells of S. cf. enopla have a protoconch with a more developed abapical spiral cord, which remains more prominent than other spirals until the initial whorls of the teleoconch. In addition, the first protoconch whorl is slightly (but not considerably) inflated. The major difference between shells from Georgia and Guadeloupe is the strength of the adapical spiral cord of the teleoconch, which is much reduced in the former, nearly indistinct. In shells from Guadeloupe, the adapical spiral cord reaches the same size as other cords only in the 21 th –23 th whorl, but such an equivalence of strength seems impossible to be reached in larger shells from Georgia, judging from the lectotype. Because of the little available material from the type locality, the present identification is tentative until new material becomes available for comparison.

Another similar species to S. cf. enopla is Inella pseudotorticula Rolán & Lee, 2008 from Bermuda. These two species mainly differ by their color pattern, which is entirely white in S. cf. enopla , but with white whorls alternating with light brown whorls in I. pseudotorticula ( Rolán & Fernández-Garcés 2008) . The types of Inella apexbilirata Rolán & Fernández-Garcés, 2008 , from the Bahamas, have the first protoconch whorl not inflated, but with spiral cords emerging since its beginning (whereas they gradually appear in the protoconch of S. cf. enopla ). In addition, the types of I. apexbilirata are small adults, reaching only 3.5 mm in length for ~nine teleoconch whorls vs 9.9–15.3 mm for a maximum of 25 teleoconch whorls in adults of S. cf. enopla .

A peculiar shell from Guadeloupe ( Fig. 8G–H ) has reduced adapical and median spiral cords on the teleoconch when compared to typical shells of S. cf. enopla with the same number of teleoconch whorls, in addition to more convex whorls and cream patches along the teleoconch. I am undecided whether this is simply an atypical shell or a distinct species.

Geographic distribution

USA: Georgia ( Dall 1927); Cuba ( Rolán & Fernández-Garcés 2008); Guadeloupe (this study).

Bathymetric distribution

Empty shells previously known from 538–823 m ( Rolán & Fernández-Garcés 2008). This study: 343– 482 m (empty shells), 100–258 m (live specimen).

Figures

Fig. 7. Strobiligera cf. enopla (Dall, 1927). A–B. MNHN, stn DW4544, 11.6 mm. C–H. MNHN, stn DW4549, 15.3 mm, 11.5 mm, 11.1 mm. I–J. MNHN, stn DW4550, 9.9 mm. K–L. MNHN, stn DW4572, 13.2 mm. Scale bars: A, C, E, G, I, K = 1 mm; B, D, F, H, J, L = 500 µm.

Fig. 8. Strobiligera cf. enopla (Dall, 1927). A–B. MNHN, stn DW4555, 11.1 mm. C–D. MNHN, stn DW4556, 7.3 mm. E. MNHN, stn DW4544 (same shell as Fig. 7A). F. MNHN, stn DW4550 (same shell as Fig. 7I). G–H. MNHN, stn DW4555, 4.9 mm. Scale bars: A, C, E–G = 1 mm; B, D, H = 500 µm.