Inella

Fernandes, Maurício Romulo & Pimenta, Alexandre Dias, 2019, Taxonomic review of Inella and Strobiligera (Gastropoda: Triphoridae) from Brazil, Zootaxa 4613 (1), pp. 1-52 : 29-31

“ Inella ” maculata sp. nov.

Figure 15

urn:lsid:zoobank.org:act:667B1EA1-E5CF-42FC-85D8-D0E174AD95AA

Type material. Holotype: MNRJ 32392 , v/2009 . Paratypes: Brazil: Espírito Santo state: IBUFRJ 19502 , REVIZEE- Central C 1-VV38 [4] . Rio de Janeiro state: MNRJ 18966 , 23 º 04ʹ 14ʺ S, 40º 59ʹ 31ʺ W, 100 m, 17/xii/2004 [2] .

Other material examined. Brazil: Espírito Santo state: MNRJ 30698 , 19 º 26ʹ 22ʺ S, 39º 15ʹ 22ʺ W, 51 m, x/2003 [1]; IBUFRJ 19604, REVIZEE-Central C1-VV38 [5]; MNRJ 32660 , 20 º 14ʹ S, 40º 12ʹ W, vi/2008 [1]; MNRJ 33798 , REVIZEE-Central C1-VV21 [1]; MNRJ 33790 , REVIZEE-Central C6-Y7 [1]; IBUFRJ 19695, Piú- ma, 1993 [9]. Almirante Saldanha Seamount: MNRJ 33761 , REVIZEE-Central C1-D1 [2] . Rio de Janeiro state: IBUFRJ 7683, 22º 08ʹ S, 40º 31ʹ W, 55 m, 29/viii/1979 [1]; IBUFRJ 19595, REVIZEE-Central C1-D3 [2]; MNRJ 32393 , type locality, v/2009 [1] .

Type locality. 23º 05ʹ S, 40º 59ʹ W, 100 m, Rio de Janeiro state, Brazil .

Etymology. maculata, L. = stained. It alludes to the color pattern of this shell.

Diagnosis. Protoconch with two main spiral cords and a nodulose subsutural spiral thread; median spiral cord usually emerges on the second or third teleoconch whorl; teleoconch with irregular light brown/orange patches often comprising all spiral cords on the same whorl.

Description. Shell sinistral, elongated, conical, rectilinear profile, reaching 9.69 mm in length, 2.07 mm in width, length/width ratio 3.8 to 4.6. Protoconch subcylindrical/columnar, robust, 0.67–1.13 mm in length, 0.57–0.82 mm in width of its last whorl; three to four slightly convex whorls, weak distinction between protoconch and teleoconch; nucleus very small, slightly elevated, in an oblique descent, mainly smooth; two main spiral cords present from nearly the beginning of the protoconch, the abapical one initially slightly more prominent, but gradually both assume the same size, situated at 29–31% and 63–73% of last whorl height; a small subsutural spiral thread is also present, crossed by small axial wrinkles, resulting in a very nodulose sculpture of this spiral thread; the adapical spiral cord is slightly to moderately nodulose, especially on the last whorl, but the abapical one is smooth. Teleoconch with up to 12 whorls; two spiral cords (adapical and abapical) in the beginning, both continuous with those of the protoconch; median spiral cord emerges narrowly at the end of the first to the beginning of the fourth whorl, but usually on the second/third whorl, reaching the same size of other cords after two to 3.5 whorls; on the body whorl, distance between spiral cords is 1.1 to 1.2 times the width of cords; 19 to 22 nearly orthocline to strongly opisthocline axial ribs; rounded nodules of a medium to moderately large size; distinct, well-developed suture, with a small sutural cord; very nodulose subperipheral cord, two basal cords, the adapical one nodulose and close to the subperipheral cord, the abapical one smooth; a small supranumerical cord may develop between the median and abapical spiral cords; ovate aperture, length/width ratio 1.3; anterior canal curved downwards/backwards, moderately short to medium, and partly closed, length/width ratio 1.4; posterior canal a deep sinus, not detached from the aperture. Protoconch brown; cream/whitish background of teleoconch, with irregular, axially disposed, light brown/orange patches often comprising all spiral cords on the same whorl, and usually not exceeding a width of three axial ribs, but in late whorls of some shells the colored patches can fill the width of several axial ribs; light brown/orange base.

Remarks. “ Inella ” maculata sp. nov. presents a considerable range in the dimensions of the protoconch, which can be explained by the number of whorls attained (three to four), and in the emergence and strengthening of the median spiral cord of the teleoconch; notwithstanding, these features represent continuous intraspecific variations. An anomalous shell from Espírito Santo state ( Fig. 15D, J ), with smaller dimensions (0.61 mm in length, 0.53 mm in width) of a golden protoconch (not brown as in typical shells), is tentatively referred to this species.

The light brown/orange patches on the teleoconch of “ Inella ” maculata sp. nov. ( Fig. 15 A–D) resemble those on the shell of “ Inella ” faceta sp. nov. ( Fig. 14 A–D). The main differences between them are related to an axial pattern of coloration in “ Inella ” maculata sp. nov. (but spirally oriented on the adapical spiral cord of “ Inella ” faceta sp. nov.), the earlier emergence of the median spiral cord of the teleoconch in “ Inella ” maculata sp. nov. (usually on the second/third whorl, but on the sixth whorl in “ Inella ” faceta sp. nov.) and very different protoconch sculptures. Despite the same pattern of coloration, Inella sp. 1 has the adapical spiral cord of teleoconch initially reduced ( Fig. 5I ), instead of the median one emerging later in “ Inella ” maculata sp. nov. ( Fig. 15F ), in addition to significant differences in protoconch sculpture. The teleoconch of “ Inella ” maculata sp. nov. is most similar to that of Nototriphora decorata (C.B. Adams, 1850) , a very common species in the tropical western Atlantic. The protoconch of “ Inella ” maculata sp. nov. is similar to that of the Australian species Inella intercalaris Marshall, 1983 , although the teleoconch of the latter species belongs to the Inella s.s. group ( Marshall, 1983: fig. 12B).

Geographical distribution. Brazil: Espírito Santo, Almirante Saldanha Seamount and Rio de Janeiro.

Bathymetric distribution. 51–105 m.

Figures

FIGURE 5. Inella sp. 1. A. MNRJ 34230, 7.00 mm. B. MNRJ 34230, 6.00 mm. C. MNHN, 5.81 mm. D. IBUFRJ 19605, 1.71 mm. E–J: same shell as A. Scale bars: A–E, 1 mm; F–H, 500 µm; I–J, 100 µm.

FIGURE 14. “Inella” faceta sp. nov. A. MNRJ 18712, holotype, 8.78 mm. B. MNRJ 32062, paratype, 7.34 mm. C. MNRJ 32913, paratype, 7.72 mm. D. IBUFRJ 2319, paratype, 7.88 mm. E–J: holotype. K–M: same shell as B. Scale bars: A–E, 1 mm; F–H, 500 µm; I, L, 50 µm; J–K, M, 100 µm.

FIGURE 15. “Inella” maculata sp. nov. A. MNRJ 32392, holotype, 9.69 mm. B. IBUFRJ 19502, paratype, 6.45 mm. C. MNRJ 18966, paratype, 6.35 mm. D. MNRJ 32660, 6.50 mm. E–I, K: holotype. J: same shell as D. Scale bars: A–E, 1 mm; F–H, 500 µm; I–K, 100 µm.