Acteon, Montfort, 1810

Valdés, Ángel, 2008, Deep-sea “ cephalaspidean ” heterobranchs (Gastropoda) from the tropical southwest Pacific, Mémoires du Muséum national d'Histoire naturelle 196, pp. 587-792 : 625-626

publication ID

978-2-85653-614-8

persistent identifier

https://treatment.plazi.org/id/03D087B2-FFC2-BE09-FF01-726AF65BFBBB

treatment provided by

Felipe

scientific name

Acteon
status

n. sp.

Acteon View in CoL ” osexiguus n. sp.

Figs 17E, 18, 19A

TYPE MATERIAL. — Holotype MNHN 20313 and paratype MNHN 20314.

TYPE LOCALITY . — Loyalty Ridge, 21°28’S, 166°26’E, 1950 m [BIOGEOCAL: stn KG 241 ] GoogleMaps .

MATERIAL EXAMINED. — Loyalty Ridge. BIOGEOCAL: stn KG 241, 21°28’S, 166°26’E, 1950 m, 1 dd, holotype (MNHN 20313; Figs 17E, 19A); stn DW 289 , 20°36’S, 167°00’E, 830-840 m, 1 dd, paratype (MNHN 20314) GoogleMaps .

DISTRIBUTION. — Collected only from New Caledonia (Fig. 18), shells only in 840-1950 m .

DESCRIPTION. — Shell morphology. Length 4 mm, width 2 mm (holotype). Shell solid, elongate, with convex sides (Fig. 19A). Body whorl large, about 4/5 of the shell length. Spire short, rounded, with 2 whorls. Suture channeled. The protoconch was eroded in all specimens examined. Umbilicus closed. Aperture very short and narrow, wider anteriorly, about 1/2 of the body whorl length. Columellar margin conspicuously thickened, with no folds or teeth. Sculpture of several punctuated spiral grooves (Fig. 17E). The punctuations are small, regularly oval, and separated from each other within each groove. The grooves are separated by gaps that are several times wider than the grooves. Colour uniformly whitish.

Anatomy. Unknown. All shells collected lacked soft parts.

REMARKS. — “ Acteon ” osexiguus is clearly distinguishable from other species of Acteonidae by the small size of the aperture in comparison to the size of the shell.

A definitive generic placement for this species is not possible until complete specimens become available for study. ETYMOLOGY. — From the Latin os (opening) and exiguus (little), in reference to the reduced aperture of this species.

FIG. 18. Collection localities of species of “ Acteon ” in the southwest Pacific: °, “ Acteon ” rhektos n. sp. Z, “ Acteon ” profundus n. sp. •, “ Acteon ” osexiguus n. sp.

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