Typhinellus constrictus, Roland & Virginie, 2015

Roland, Houart & Virginie, Héros, 2015, New species of Muricidae Rafinesque, 1815 (Mollusca: Gastropoda) from the Western Indian Ocean, Zoosystema 37 (3), pp. 481-503 : 498-500

Typhinellus constrictus n. sp.

( Figs 10 L-P; 13A)

TYPE MATERIAL. — Holotype (lv) MNHN-IM-2009-14446 and 5 paratypes MNHN; 1 paratype coll. RH (as listed below).

TYPE LOCALITY. — Madagascar, sector of Fort-Dauphin, 25°15.0’S, 47°14.5’E, 97- 98 m. [ATIMO VATAE: stn BS09].

MATERIAL EXAMINED. — South Madagascar. ATIMO VATAE: stn BS09, Rocher de l’Albatros, 25°29’S, 44°57’E, 11-13 m, 1 lv (holotype MNHN-IM-2009-14446). — Stn BP22, West sector of Lavanono, 25°23’S, 44°52’E, 20-22 m, 1 lv (paratype MNHN- IM-2009-22522 BOLD ID BOMGA027-15, GenBank accession number KP697991 for COI gene KC860506 ). — Stn BP42, West sector of Lavanono, 25°23-24’S, 44°51.1’E, 18-21 m 1 dd (paratype MNHN-IM-2000-30021). — Stn CP3511, sector of Fort-Dauphin, 25°15’S, 47°15’E, 97-98 m, 1 dd (paratype MNHN- IM-2000-30022). — Stn CP3560, East of Faux-Cap, 25°37’S, 46°10’E, 102-106 m, 2 dd (2 paratypes MNHN-IM-2000-30023). — Stn CP3622, Southeast of Faux-Cap, 25°43’S, 45°59’E, 84-88 m, 1 dd (paratype Coll. RH). — No data, South Madagascar, sector of Fort Dauphin, 1 dd (MNHN).

DISTRIBUTION. — South Madagascar, taken alive at 13-20 m, empty shells at 21- 102 m.

ETYMOLOGY. — Latin, constrictus , constricted. This species is named for the peculiar form of the teleoconch whorl.

DESCRIPTION

Shell large for the genus, up to 20.7 mm in height at maturity (holotype), although one incomplete paratype (MNHN) would have been larger. Height/width ratio 1.73 (holotype). Slender, narrowly ovate with expanded shoulder, lightly built. Subsutural ramp broad, almost horizontal, weakly convex.

Tan or light brown, subsutural ramp darker. Abapertural side of apertural flange and ventral part of siphonal canal beige or light tan. Three or four axial, narrow, brown bands on partition. Aperture white.

Spire high with paucispiral, weakly shouldered protoconch (observed in one specimen but partly broken).Teleoconch up to five angulate, strongly shouldered whorls. Abapical part of whorls constricted. Suture impressed.

Axial sculpture of teleoconch whorls consisting of four, low, thin, sharp lamellate varices, each with a weakly open, inward curved shoulder spine. Apertural varix thin, broad, constricted medially, broader at abapical extremity, extending from shoulder spine almost to tip of siphonal canal. Apertural shoulder spine adapically bent, long, narrowly triangular, straight, connected to last teleoconch whorl by a broad, thin, lamellate partition. Partition with two or three backward bent, short, flattened, broad spinelets. Spiral sculpture very faint, consisting of P1 with the anal tube, P2 (shoulder), P3, P4 and P5 only discernable on variceal flange and only very weakly between axial varices, corresponding to the broad, weakly curved abapertural spinelets at outer apertural margin. P1 with long, rounded, ventrally sealed anal tube, forming an angle of approximately 85-90° with axis of shell. Only apertural tube hollow and functional, older tubes broken off and closed. Two narrow spiral cords between abapical part of aperture and variceal flange, occasionally obvious in some shells. Other sculpture of few, weak and very thin, low, broad scales, only visible on last teleoconch whorl, between axial varices.

Aperture small, rounded, erect, forming a continuous peristome. Columellar lip narrow, outer lip smooth within. Siphonal canal long, broad, straight, ventrally sealed, dorsally bent at tip. Left side of canal weakly overlapping right side.

Operculum and radula unknown.

REMARKS

Typhinellus constrictus n. sp. differs from all the other Typhinellus species in having a broad, almost straight shoulder ramp, deeply constricted teleoconch whorls with an impressed suture and a rounded aperture.

FIG. 13.— Distributions of: A, Typhinellus constrictus n.sp.; B, Siphonochelus (Siphonochelus) aethomorpha n. sp. Symbols: ★, type locality; ■, other occurences.

Genus Siphonochelus Jousseaume, 1880

Subgenus Siphonochelus Jousseaume, 1880

TYPE SPECIES. — Typhis arcuatus Hinds, 1843 , South Africa (by original designation).

Figures

FIG. 10. — A-F, Typhinellus laminatus n. sp.; MIRIKY, stn DW3245, 90-257 m; A-C, holotype MNHN IM-2000-30019, 16.3 mm; D, E, paratype MNHN IM-2000- 30020, 14.8 mm;F, protoconch; G, H, Typhinellus bicolor Bozzetti, 2007;South Madagascar, Lavanono,holotype MNHN IM-2000-20852, 21.2 mm; I, J Typhinel- lus amoenus (Houart,1994), Umhlanga Rocks, Natal, South Africa, holotype NMSA S436, 21 mm, photo courtesy A. Marais;K, Typhinellus androyensis Bozzetti, 2007;ATIMO VATAE,BB04,14-18 m, 14.9 mm; L-P, Typhinellus constrictus n. sp.: L-N, ATIMO VATAE,BS09,11-13 m, holotype MNHN IM-2009-14446, 15.4 mm; O, P, ATIMO VATAE, stn CP3511, 97-98 m, paratype MNHN IM-2000-30022 20.7 mm. Scale bar: F, 500 µm.