Liostomia canaliculata, Ortega & Gofas, 2019

Ortega, José Rafael & Gofas, Serge, 2019, The unknown bathyal of the Canaries: new species and new records of deep-sea Mollusca, Zoosystema 41 (26), pp. 513-551 : 544

Liostomia canaliculata n. sp.

( Fig. 25J, K )

urn:lsid:zoobank.org:act:156041FB-BB06-4A69-B683-2E03FBEBF626

TYPE MATERIAL. — Holotype. sh., MNHN-IM-2000-34278, from SEAMOUNT 2 DW130 .

TYPE LOCALITY. — Off W Gran Canaria, 28°08.95’N, 15°53.11’W / 28°09.06’N, 15°52.92’W, 655- 660 m.

ETYMOLOGY. — Latin adjective meaning “channelled”, alluding to the subsutural channel.

DESCRIPTION

Shell minute, globose with a low, markedly stepped spire, and the last whorl occupying more than 4⁄5 of the total height. Protoconch c. 280 µm in diameter, with its apex obliquely immersed in the first teleoconch whorl (type B of van Aartsen, 1987), smooth and glossy.Teleoconch of two whorls, shouldered with a very strong keel separated from the suture by a broad channel, smooth except for growth lines which are particularly conspicuous within the subsutural channel. Last whorl with maximum convexity near the periphery, flat between keel and periphery and only slightly convex in the abapical part. Umbilicus broad and conspicuous, delimited by a blunt keel. No columellar tooth. Dimensions of the holotype: 1.0 mm height × 0.95 mm diameter.

REMARKS

This species does not resemble any known gastropod from the North Atlantic, but is clearly identified as a member of the Pyramidellidae by the heterostrophic protoconch. Among all the pyramidellid genera reported in the area, Liostomia was considered because its type species, although quite different in aspect, is also umbilicate, has the protoconch nucleus similarly immersed, lacks a columellar tooth, and has an incipient subsutural keel on the first teleoconch whorl, admittedly not so conspicuous ( HØisaeter 2014). Liostomia mamoi Mifsud, 1993 was described from the Mediterranean and has a height/diameter ratio close to that of L. canaliculata n. sp., although lacking the spiral keels.

Figures

FIG. 25. — A-C, Spirolaxis lamellifer (Rehder, 1935), shell from DW120 (diameter 3.7 mm); new to the Canaries; D-F, Orbitestella pruinosa n. sp., holotype from DW130 (diameter 0.8 mm); G, Graphis gracilis (Monterosato, 1874), shell from DW130 (height 2.1 mm); H, I, Odostomia madeirensis Peñas, Rolán & Swinnen, 2014, shell from DW133 (height 2.2 mm); new to Spanish waters; J, K, Liostomia canaliculata n. sp., holotype from DW130 (height 1 mm); L, M, Ringicula pirulina Locard, 1897, shell from DW130 (6.4 mm); N, Colpodaspis pusilla M. Sars, 1870, shell from DW126 (1.4 mm); new to the Canaries.