Hyalorisia madagascarensis Fassio, Bouchet & Oliverio, 2020

Fassio, Giulia, Russini, Valeria, Buge, Barbara, Schiaparelli, Stefano, Modica, Maria Vittoria, Bouchet, Philippe & Oliverio, Marco, 2020, High cryptic diversity in the kleptoparasitic genus Hyalorisia Dall, 1889 (Littorinimorpha: Capulidae) with the description of nine new species from the Indo-West Pacific, Journal of Molluscan Studies (Rijksuniversiteit te Gent. Fakulteit van de Landbouwkundige en Toegepaste Biologische Wetenschappen) 86 (4), pp. 401-421 : 417

Hyalorisia madagascarensis Fassio, Bouchet & Oliverio new species

MOTU-10 ( Figs 3J , 6B , 7H, Q )

Type material: Holotype: off Mahajanga, NW Madagascar, MIRIKY, Stn CP3268 , 15°31 S, 45°45 E, 640–800 m, MNHN-IM-2007-39090 .

Material examined: The holotype and one other specimen ( MNHN-IM- 2007-39292).

Etymology: After the general area of occurrence, Madagascar.

ZooBank registration: urn:lsid:zoobank.org:act:5D585AFC-B8C7-4639-9535-74CA13427627 .

COI-based diagnosis: Nine diagnostic (autapomorphic) positions in the alignment: 40(G), 103(C), 158(C), 283(G), 529(C), 553(C), 556(C), 605(T) and 628(G).

Shell (data for holotype shown within parentheses): Size small to medium for genus: length 6.5–11 (6.5) mm, width 4.5–9 (4.5) mm, height 2–3 (2) mm; thin, ellipsoidal or rounded, depressed; white shell surface with smooth yellowish periostracum; anterior margin rounded; protoconch of 0.9 whorl, diameter of nucleus 0.19 mm; teleoconch smooth except for distinct commarginal growth ridges; apertural margin thin, interior glossy white; lamella from wide to narrow, width 0.8–0.92 (0.8) mm.

Soft parts (ethanol preserved): Cephalic tentacles whitish with grey base; pseudoproboscis whitish.

Radula: Taenioglossate, 2-1-R-1-2; marginal teeth sickle shaped; internal marginals with a few denticles on the inner edge; lateral teeth triangular, highly denticulated on both edges; rachidian tooth triangular, highly denticulated on both edges.

Host: Holotype attached to P. caducum (MNHN-IM-2007-39094). The second specimen of this Hyalorisia species (MNHN-IM-2007-39092) has a registration number close to that of a specimen of P. sibogai (MNHN-IM-2007-39097); the latter shows a mark on the shell that corresponds to the contour of the Hyalorisia specimen.

Distribution: So far known only from Madagascar, at depths 425– 640 m.

Remarks: Off Mahajanga, Madagascar (MIRIKY: Stn CP3268), Hyalorisia madagascarensis n. sp. was found sympatrically with H. lehibe n. sp. (MOTU-5) and syntopically with H. kely n. sp. (MOTU-7).

Figures

Figure 3. Protoconchs of Hyalorisia. A. Hyalorisia galea, MNHN-IM-2013-61536. B. Hyalorisia neocaledonica n. sp., MNHN-IM-2013-65907. C. Hyalorisia tosaensis, MNHN-IM-2007-34794. D. Hyalorisia nupta n. sp., MNHN-IM-2007-34005. E. Hyalorisia lehibe n. sp., MNHN-IM-2007-39212. F. Hyalorisia nanhaiensis n. sp., MNHN-IM-2013-34796. G. Hyalorisia kely n. sp., MNHN-IM-2007-38809. H. Hyalorisia melanesica n. sp., MNHN-IM-2013-58359. I. Hyalorisia profunda n. sp., MNHN-IM-2007-33828. J. Hyalorisia madagascarensis n. sp., MNHN-IM-39292. K. Hyalorisia solomonensis n. sp., MNHN-IM-2007-34215. Scale bars = 100 µm.

Figure 6. Shells of Hyalorisia (A–C) and detail of the lamella (D, E). A. Hyalorisia profunda, holotype, MNHN-IM-2013-59695, South China Sea (L = 7 mm). B. Hyalorisia madagascarensis n. sp., holotype, MNHN-IM-2007-39090, off Mahajanga, Madagascar (L = 6.5 mm). C. Hyalorisia solomonensis n. sp., holotype, MNHN-IM-2007-34203, SE of Santa Isabel, Solomon Islands (L = 8 mm). D. Wide lamella of Hyalorisia neocaledonica n. sp., MNHN-IM-2013-65645, Lord Howe Rise, New Caledonia. E. Narrow lamella of Hyalorisia tosaensis, MNHN-IM-2013-58352, New Ireland, Papua New Guinea. Scale bars = 2 mm.

Figure 7. Radulae of Hyalorisia (A–I) and detail of the rachidian tooth (J–R). A, J. Hyalorisia galea MNHN-IM-2013-60195. B, K. Hyalorisia neocaledonica n. sp., MNHN-IM-2013-65647. C, L. Hyalorisia tosaensis, MNHN-IM-2013-58352. D, M. Hyalorisia nupta n. sp., MNHN-IM-2013-68952. E, N. Hyalorisia nanhaiensis n. sp., MNHN-IM-2013-59697. F, O. Hyalorisia kely n. sp., MNHN-IM-2007-38809. G, P. Hyalorisia melanesica n. sp., MNHN-IM-2007-34205. H, Q. Hyalorisia madagascarensis n. sp., MNHN-IM-2007-39090. I, R. Hyalorisia solomonensis n. sp., MNHN-IM-2007-34215. Scale bars = 100 µm.