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 : 629-631

publication ID

978-2-85653-614-8

persistent identifier

https://treatment.plazi.org/id/03D087B2-FFCE-BE02-FF01-757DF248FE69

treatment provided by

Felipe

scientific name

Acteon
status

n. sp.

Acteon View in CoL ” comptus n. sp.

Figs 19F, G, 20B, 21

TYPE MATERIAL. — Holotype MNHN 20293 and 5 paratypes MNHN 20294-20298, 2 paratypes LACM 2986 View Materials .

TYPE LOCALITY. — Loyalty Ridge, 21°00’S, 166°58’E, 1820-1980 m [BIOGEOCAL: stn CP 260] GoogleMaps .

MATERIAL EXAMINED. — Indonesia. KARUBAR: stn DW 49 , ( MNHN 20293 View Materials ; Figs 19F, 20B) and paratype ( MNHN 20294 View Materials ); Tanimbar Islands , 08°00’S, 132°59’E, 206-210 m, 2 dd. stn DW 296 , 20°38’S, 167°10’E, 1230-1270 m, 1 dd, paratype Loyalty Ridge. BIOCAL: stn KG 96, 21°23’S, 166°30’E, 2377 m, ( MNHN 20295 View Materials ); stn DW 313 , 20°59’S, 166°59’E, 1600-1640 m, 1 dd, paratype ( MNHN 20297 View Materials ); stn DS 98, 21°24’S, 166°30’E, 1 dd, paratype ( MNHN 20296 View Materials ; Fig. 19G) GoogleMaps .

2365-2470 m, 2 dd, paratypes ( LACM 2986 View Materials ) . — BIOGEOCAL: Vanuatu. MUSORSTOM 8: stn DW 987 , 19°23’S, 169°35’E, stn CP 260, 21°00’S, 166°58’E, 1820-1980 m, 2 dd, holotype 1040-1050 m, 1 dd, paratype ( MNHN 20298 View Materials ) GoogleMaps .

DISTRIBUTION. — Collected from Indonesia, New Caledonia and Vanuatu (Fig. 21), in 210-2377 m.

DESCRIPTION. — Shell morphology. Length 7 mm, width 3.5 mm (holotype). Shell solid, elongate, with convex sides (Fig. 19F). Body whorl comparatively short, less than 2/3 of the shell length. Spire very long, conical, with 3 long whorls. Suture deeply channeled. Protoconch globose, about 1.5 whorls and 400 Μm in diameter (Fig. 19G). Umbilicus closed. Aperture short and narrow, wider anteriorly, about 2/3 of the body whorl length. Columellar margin conspicuously thickened, with no folds or teeth. Sculpture of several punctuated spiral grooves (Fig. 20B). The punctuations are large, regularly oval, and partially fused to the next one within each groove. The grooves are separated by gaps that increase in width towards the posterior end of the spire. The grooves increase in width towards the anterior end of the shell with the exception of a wide groove composed of very elongate and compressed punctuations situated at the edge of the spire. Colour uniformly dirty white.

Anatomy. Unknown. All shells collected lacked soft parts.

REMARKS. — The shell morphology of “ Acteon ” comptus resembles that of “ Acteon ” profundus n. sp. especially in the shell sculpture. However, these two species are easily distinguishable by the longer shell and spire of “ A. ” comptus and the presence of a large area with no spiral grooves in the shell of “ A. ” profundus.

The two shells from Indonesia were found in much shallower waters than the rest of the material, which may suggest that the Indonesian material belongs to a different species, although it is conchologically indistinguishable from the type material.

FIG. 20. Shell morphology and sculpture of species of “ Acteon ”. A, “ Acteon herosae n. sp. sculpture of paratype MNHN 20307 from Vanuatu, MUSORSTOM 8 stn DW 1101, scale bar = 200 Μm. B, “ Acteon ” comptus n. sp., sculpture of holotype MNHN 20293, New Caledonia, BIOGEOCAL stn CP 260, scale bar = 200 Μm. C, “ Acteon ” chauliodous n. sp., holotype MNHN 20284 (6 mm) long, ventral view, BATHUS 1 stn DE 697; D, protoconch of paratype MNHN 20287, New Caledonia, BATHUS 2 stn DW 717, scale bar = 300 Μm; E, sculpture of holotype MNHN 20284, BATHUS 1 stn DE 697, scale bar = 200 Μm.

A definitive generic placement for this species is not possible until complete specimens become available for study.

ETYMOLOGY. — From the Latin comptus (ornamented), in reference to the complex sculpture of this species.

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