Inella apexbilirata Rolán & Fernández-Garcés, 2008

Fernandes, Maurício Romulo & Pimenta, Alexandre Dias, 2019, Taxonomic review of Inella and Strobiligera (Gastropoda: Triphoridae) from Brazil, Zootaxa 4613 (1), pp. 1-52 : 9-11

Inella apexbilirata Rolán & Fernández-Garcés, 2008

Figures 3Y , 4

Triphora compsa: Absalão (1989: 3) , non Dall, 1927.

Inella apexbilirata Rolán & Fernández-Garcés, 2008: 104 , fig. 12C–E.

Type material. Holotype: ANSP 367841 ( Fig. 3Y ) . Paratypes: ANSP 367840 , type locality [4] .

Type locality. 26º 29 ʹ 45ʺ N, 78º 37ʹ 15ʺ W, 300 m, Lucaya , Grand Bahama Island, Bahamas .

Material examined. The type material and: Brazil: Espírito Santo state: IBUFRJ 19619, REVIZEE-Central C1-VV38 [1]. Almirante Saldanha Seamount: MNRJ 33780 , REVIZEE-Central C1-D1 [1]. Rio de Janeiro state: MNRJ 18302 , HAB 13-H4 [2]; MNRJ 18412 , HAB 16-H4 [1]; MNRJ 18300 , HAB 11-G4 [1]; MNRJ 18402 , HAB 16-G4 [1]; MNRJ 18301 , HAB 13-D3 [1]; MNRJ 31124 , 22 º 42ʹ S, 40º 40ʹ W, 110–120 m, xii/2001 [2]; MNRJ 32629 , 22 º 42ʹ S, 40º 40ʹ W, 110–120 m, viii/2002 [2]; MNRJ 30868 , 22 º 42ʹ S, 40º 40ʹ W, 110–120 m, 19/ix/2003 [3]; MNRJ 31108 , 22 º 42ʹ S, 40º 40ʹ W, 110–120 m, xi/2007 [2]; MNRJ 18379 , HAB 16-C3 [1]; IBUFRJ 19577, 22º 48ʹ S, 40º 45ʹ W, 106–110 m, 27/i/1998 [28]; IBUFRJ 19533, REVIZEE-Central C1-D1-2 [2]; MNRJ 18423 , HAB 16-C4 [2]; MNRJ 33806 , 23 º 03ʹ 00ʺ S, 41º 04ʹ 06ʺ W, 98 m, 12/iv/1995 [2]; MNRJ 32043 , 23 º 03ʹ 18ʺ S, 41º 02ʹ 06ʺ W, 97 m, x/2008 [3]; MNRJ 18965 [20], MORG 50111 [46], 23º 04ʹ 14ʺ S, 40º 59ʹ 31ʺ W, 100 m, 17/xii/2004; MNRJ 31115 , 23 º 04ʹ 14ʺ S, 40º 59ʹ 31ʺ W, 100 m, iii/2005 [4]; MNRJ 32354 , 23 º 04ʹ 14ʺ S, 40º 59ʹ 31ʺ W, 100 m, vii/2005 [3]; MNRJ 18948 [6], MNRJ 26603 [16], MNRJ 33075 [11], MNRJ 33076 [5], MORG 47452 [7], MORG 47495 [5], MORG 48069 [5], MORG 48131 [9], MORG 48182 [2], MORG 48195 [5], MORG 48220 [2], MORG 48264 [5], MORG 48430 [7], MORG 48556 [2], MORG 48573 [5], MORG 48610 [6], MORG 48614 [1], 23º 05ʹ S, 40º 58ʹ W, 100 m; MNRJ 32391 , 23 º 05ʹ S, 40º 59ʹ W, 100 m, v/2009 [12]; MNRJ 30867 , 23 º 05ʹ 23ʺ S, 40º 58ʹ 55ʺ W, 100 m, 17/i/2004 [5]; MNRJ 32072 , 23 º 09ʹ 00ʺ S, 41º 02ʹ 06ʺ W, 100 m, x/2008 [5]; MNRJ 18368 , HAB 16-B4 [2]; MNRJ 18299 [5], MNRJ 18703 [1], HAB 11-B5; MNRJ 18426 , HAB 16-B5 [3]; MNRJ 32061 , 23 º 13ʹ 30ʺ S, 41º 21ʹ 00ʺ W, 93 m, x/2008 [6]; MNRJ 32403 , 23 º 18ʹ 35ʺ S, 41º 14ʹ 03ʺ W, 100 m [1]; MNRJ 32048 , 23 º 39ʹ 00ʺ S, 41º 24ʹ 00ʺ W, 154 m, x/2008 [2]; MNRJ 32038 , 24 º 07ʹ 44ʺ S, 44º 15ʹ 12ʺ W, 142 m, x/2008 [1]; MNRJ 32040 , 24 º 12ʹ 20ʺ S, 44º 16ʹ 34ʺ W, 145 m, x/2008 [2]; IBUFRJ 8992, Campos Basin , Oc. Ship Astro Garoupa coll., 1984 [1] ; MORG 39386 , Campos Basin , 1997 [1] ; MNRJ 27846 , REVIZEE-Sul sta. 6666 [2]. São Paulo state: MNRJ 27847 , PADCT sta. 6573 [5]; MNRJ 27853 , REVIZEE-Sul sta. 6676 [4]; MNRJ 60188 , PADCT sta. 6577 [1].

Description. Shell sinistral, elongated, conical/fusiform, with rectilinear profile, reaching 11.21 mm in length, 1.80 mm in width, ratio length/width 4.0 to 6.1. Protoconch subcylindrical/columnar, 0.63–0.71 mm in length, 0.54– 0.62 mm in width in its last whorl; 2.25 to 3.25 convex protoconch whorls, weak distinction between protoconch and teleoconch; nucleus very small, slightly elevated, in an oblique descent; two main strong spiral cords present from the beginning of the protoconch, with nearly the same size, situated at 34% and 72% of last whorl height, in addition to a small subsutural cord, more evident in the last whorl; axial sculpture entirely absent. Teleoconch with up to 16.5 whorls; three spiral cords in the beginning, all of them continuous with those of the protoconch; adapical spiral cord very close to the median cord and narrower than other cords through first whorls of teleoconch, but ac- quiring nearly the same size as others on the eighth/twelfth whorl; on the body whorl, distance between spiral cords is equal or as much as twice the width of cords; 13 to 16 nearly orthocline axial ribs, rarely slightly opisthocline; rounded (especially the adapical and median cords) to slightly elliptical (especially the abapical cord) nodules of a medium to moderately large size; distinct but little developed suture, with a small sutural cord; thick, smooth subperipheral cord, two to three smooth basal cords, the adapical one thick and very close to the subperipheral cord, the other two (or one) usually thin; no supranumerical cords; ovate aperture, 0.61–0.95 mm long, 0.47–0.82 mm wide, ratio length/width 1.0–1.3; anterior canal very short, directed downwards/backwards, and open, sometimes partially crossed in its base by the projection of the outer lip, 0.20–0.29 mm long, 0.22–0.29 mm wide, ratio length/width 0.9–1.2; posterior canal as a small notch, 0.11–0.34 mm long. Light brown/beige shell, apex (protoconch and one/ two initial whorls of teleoconch) slightly lighter; nodules of teleoconch usually somewhat lighter than internodular spaces.

Remarks. This is by far the most common species of Inella in Campos Basin , southeastern Brazil. The single shell from Espírito Santo state is of a very worn juvenile, thus it is uncertain if living populations of I. apexbilirata indeed occur in Brazil north of Campos Basin.

The type material of I. apexbilirata ( Fig. 3Y ) is represented by five shells, at least some of which are adult ( Rolán & Fernández-Garcés 2008), but the maximum shell length is only 3.5 mm for about nine whorls of teleoconch, in contrast to 11.21 mm for 16.5 whorls in shells from Brazil (those between 8.5 and 9.5 whorls of teleoconch reach from 4.1 to 4.8 mm long). It remains unclear if Caribbean specimens can reach larger dimensions, owing to the scarcity of available material. The most remarkable difference between shells from the Caribbean and Brazil is related to shell color: white in the former, light brown in the latter ( Fig. 4 A–E). A few Triphoridae species present polychromatism in the shell along their geographical distribution, like the usually white shells in Caribbean but usually light brown shells in Brazil of Metaxia rugulosa (C.B. Adams, 1850) ( Fernandes & Pimenta 2011) . In spite of it, no available shell of Caribbean I. apexbilirata is light brown, nor is any shell from Brazil white. Another difference occurs in their bathymetric range, as shells from Brazil do not seem to reach the depth of 300 m (type locality), but some juveniles were sampled down to 163 m.

The record of Triphora compsa Dall, 1927 from Brazil by Absalão (1989) actually consists of I. apexbilirata ( Fig. 4E ). Strobiligera compsa ( Fig. 3R ) is presumably restricted to the southeastern U.S.A., possessing a wider shell, larger teleoconch whorls, and a deeper bathymetric record (805 m).

Geographical distribution. Bahamas (type locality); Brazil: Espírito Santo (pending confirmation), Almirante Saldanha Seamount , Rio de Janeiro, São Paulo (this study) .

Bathymetric distribution. 69–163 m (this study) to 300 m (type locality).

Figures

FIGURE 3. Type material of some species of Inella and Strobiligera. A–B. “Inella” intermedia (Dall, 1881), lectotype MCZ 7386 (A), non-type MCZ 7385 (B). C–D. “Inella” triserialis (Dall, 1881), paralectotypes MCZ 7384 (C) and MCZ 7382 (D). E–F. “Inella” faberi Rolán & Fernández-Garcés, 2008, holotype FLMNH 291343 (E), paratype FLMNH 419388 (F). G. “Inella” differens Rolán & Lee, 2008, holotype FLMNH 419184. H–I. “Inella” undebermuda Rolán & Lee, 2008, holotype FLMNH 419181 (H), paratype USNM 1112657 (I). J. “Inella” longissima (Dall, 1881), lectotype MCZ 7381. K–L. “Inella” harryleei Rolán & Fernández-Garcés, 2008, holotype FLMNH 419182 (K), paratype FLMNH 158178 (L). M. Strobiligera sentoma (Dall, 1927), lectotype USNM 108072. N. “Inella” pseudolongissima Rolán & Fernández-Garcés, 2008, paratype FLMNH 171183. O–P. Inella pseudotorticula Rolán & Lee, 2008, holotype FLMNH 419191 (O), paratype USNM 1112658 (P). Q. Strobiligera pompona (Dall, 1927), lectotype USNM 108339. R. Strobiligera compsa (Dall, 1927), lectotype USNM 333518. S–T. Strobiligera gaesona (Dall, 1927), lectotype and paralectotype USNM 108341. U–V. Strobiligera dinea (Dall, 1927), lectotype and paralectotype USNM 333517. W. Inella colon (Dall, 1881), paralectotype MCZ 7387. X. Strobiligera enopla (Dall, 1927), lectotype USNM 108074.Y. Inella apexbilirata Rolán & Fernández-Garcés, 2008, holotypeANSP 367841, credits of image to Paul Callomon. Scale bars: A, H–R, 5 mm; B–G, S–Y, 1 mm.

FIGURE 4. Inella apexbilirata Rolán & Fernández-Garcés, 2008. A. MNRJ 33075, 8.26 mm. B. MNRJ 33075, 8.61 mm. C. MNRJ 31115, 7.38 mm. D. MNRJ 26603, 10.49 mm. E. IBUFRJ 8992, 4.19 mm. F–K: same shell as C. Scale bars: A–F, 1 mm; G–I, 500 µm; J–K, 100 µm.