Inella

Fernandes, Maurício Romulo & Pimenta, Alexandre Dias, 2019, Taxonomic review of Inella and Strobiligera (Gastropoda: Triphoridae) from Brazil, Zootaxa 4613 (1), pp. 1-52 : 20

“ Inella ” galo sp. nov.

Figure 10

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Type material. Holotype: MNRJ 29365 , P. Gonçalves coll., iii/2003 . Paratypes: Brazil: Rio de Janeiro state: MNRJ 29410 , 22 º 24ʹ 05ʺ S, 41º 05ʹ 08ʺ W, 48 m , Campos Basin [2]; MNRJ 29409 , 22 º 40ʹ 35ʺ S, 41º 43ʹ 21ʺ W, 47 m , Campos Basin [1]; MZSP 39584 [5], MORG 47194 [1], Arraial do Cabo , 25–30 m, P. Gonçalves coll., viii/2003 .

Type locality. Arraial do Cabo , 25–30 m, Rio de Janeiro state, Brazil .

Etymology. The specific epithet alludes to the citizens of Arraial do Cabo (locally known as “galo”, in Portuguese), the region where this species was exclusively found so far. Epithet as a noun in apposition.

Diagnosis. Robust shell, usually light brown/golden, with a large aperture; median spiral cord emerges very narrowly on the fourth or fifth teleoconch whorl, eventually on the sixth whorl; two supranumerical cords may develop.

Description. Shell sinistral, elongated, conical, broad at the base, nearly rectilinear profile, reaching 9.90 mm in length, 2.64 mm in width, length/width ratio 3.4 to 4.1. Protoconch subcylindrical, 0.62–0.89 mm in length, 0.53–0.66 mm in width of its last whorl; 3.25 to 4.25 convex whorls, clear distinction between protoconch and teleoconch; initial whorl dome-shaped, mainly smooth; remaining whorls with two spiral cords, situated at 33–36% and 61–73% of last whorl height, the adapical one vanishing and disappearing before the transition to the teleoconch; very small, almost indistinct, axial wrinkles above the adapical cord, being nearly orthocline. Teleoconch with up to 13 whorls; two spiral cords (adapical and abapical) in the beginning, the abapical one continuous with that of the protoconch; median spiral cord emerges very narrowly on the fourth or fifth whorl, eventually on the sixth whorl, reaching the same size of the abapical cord (the adapical one is more prominent) after 3.5 to six whorls; on the body whorl, distance between spiral cords is 0.8 to 1.5 times the width of cords; 21 to 26 orthocline to moderately opisthocline axial ribs; rounded nodules of a moderately large size, positioned very close to each other in the spiral cords; distinct and well-developed suture, with a small sutural cord; weakly nodulose to wavy subperipheral cord, one or two very narrow, smooth basal cords; two supranumerical cords may develop, one between median and abapical cords, the other between abapical and subperipheral cords; ovate, large aperture, very projected, 1.39–1.51 mm long, 1.10–1.24 mm wide, length/width ratio 1.1–1.3; anterior canal curved downwards/backwards, moderately short, open or partly closed by the projection of the outer lip, 0.47–0.66 m long, 0.34–0.56 mm wide, length/width ratio 1.1–1.6; posterior canal as a wide notch, 0.18–0.25 mm long, not detached from the aperture. Light brown/ golden shell, but the peristome and the first whorl of protoconch can be whitish; teleoconch rarely whitish.

Remarks. This species shares several similarities with “ I ”. faberi from Brazil, such as the shell coloration, the protoconch sculpture and the whorl of emergence of the median spiral cord on the teleoconch. However, a typical shell of “ Inella ” galo sp. nov. is thicker and broader, with a very projected aperture ( Fig. 10A ), narrower basal cord(s) (usually numbering only one, very close to the subperipheral cord), base not darker than remaining shell ( Fig. 10 A–D), with more axial ribs (21 to 26, instead of 16 to 22 in “ I ”. faberi ), and it may have distinct supranumerical cords ( Fig. 10G ), contrary to “ I ”. faberi . The two species are partially sympatric, with the deepest records of “ Inella ” sp. 3 coinciding with the shallowest records of “ I ”. faberi and “ Inella ” sp. 2 at a depth zone of 45– 50 m.

Some intraspecific variation is also observed in “ Inella ” galo sp. nov., especially related to the whorl of emergence and the degree of strengthening of the median spiral cord of teleoconch, the shape of the shell (robust and broad vs. elongated and slightly thinner) and the whitish coloration of one abnormal shell (Fig. 10D). This species seems to have very restricted geographical and bathymetric ranges, and future field work should be employed to properly evaluate its conservation status. Geographical distribution. Brazil: Rio de Janeiro. Bathymetric distribution. 25–48 m.

Figures

FIGURE 10. “Inella” galo sp. nov. A. MNRJ 29365, holotype, 8.09 mm. B. MZSP 39584, paratype, 7.48 mm. C. MZSP 39584, paratype, 8.47 mm, with a small barnacle adhered in it. D. MNRJ 29410, paratype, 9.90 mm. E–G, I, K: holotype. H, J: same shell as D. Scale bars: A–E, 1 mm; F–H, 500 µm; I–J, 250 µm; K, 100 µm.