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 : 631-632

“ Acteon ” chauliodous n. sp.

Figs 20C-E, 21

TYPE MATERIAL. — Holotype MNHN 20284 and 7 paratypes MNHN 20285-20288, 2 paratypes LACM 2987 .

TYPE LOCALITY . — Passe de Hienghène , east coast of New Caledonia, 20°34’S, 164°58’E, 570-650 m [ BATHUS 1 :

stn DE 697].

MATERIAL EXAMINED. — North of New Caledonia. BATHUS paratypes ( LACM 2987 ); stn DE 700, Passe de Cap Baye, 4: stn DW 903 , Grand Passage, 19°00’S, 163°14’E, 386-400 m, 20°57’S, 165°35’E, 160-222 m, 4 dd, paratypes ( MNHN 20286 ). 1 dd . — BATHUS 2 : stn DW 717 , S of Ile des Pins, 22°44’S, 167°17’E, New Caledonia proper. BATHUS 1 : stn DW 654 , Passe de Ca- 350-393 m, 1 dd, paratype ( MNHN 20287 ; Fig. 20D); stn DW nala, 21°17’S, 165°57’E, 237-298 m, 1 dd, paratype ( MNHN 754 , Passe de Dumbéa, 22°23’S, 166°13’E, 577-780 m, 1 dd, 20285); stn DE 697, Passe de Hienghène, 20°34’S, 164°58’E, paratype ( MNHN 20288 ) . — BATHUS 4 : stn DW 943 , Passe 570-650 m, 3 dd, holotype ( MNHN 20284 ; Figs 20C, E) and d’Amos, 20°12’S, 164°31’E, 316-347 m, 1 dd .

DISTRIBUTION. — Collected from New Caledonia (Fig. 21), in 222-577 m.

DESCRIPTION. — Shell morphology. Length 6 mm, width 3 mm (holotype). Shell solid, elongate, with convex sides (Fig. 20C). Body whorl large, about 2/3 of the shell length. Spire very long, conical, with 3 short whorls. Suture channeled. Protoconch globose, about 1 whorl and 350 Μm in diameter (Fig. 20D). Umbilicus closed. Aperture long and narrow, wider anteriorly, about 3/4 of the body whorl length. Columellar margin conspicuously thickened, with a single, conspicuous tooth. Sculpture of several punctuated spiral grooves (Fig. 20E). The punctuations are large, oval, almost rectangular, and partially fused to the next one within each groove. The grooves are separated by gaps that increase in width towards the centre of the whorl. The grooves increase in width towards the anterior end of the shell with the exception of 3 wider grooves, composed of elongate and compressed punctuations, situated next to each other near the posterior end of the spire. Colour uniformly dirty white.

Anatomy. Unknown. All shells collected lacked soft parts.

REMARKS. — The shape of the shell of “ Acteon ” chauliodous is similar to that of “ Acteon ” profundus n. sp., but the two species are easily distinguishable by the presence of a denticle on the columella of “ A. ” chauliodous and a large area with no spiral grooves in “ A. ” profundus. The sculpture of “ A. ” chauliodous resembles that of “ Acteon ” comptus n. sp. but differs in the position and number of the wider grooves near the posterior end of the spire: 3 subterminal grooves in “ A. ” chauliodous, only 1 terminal groove in “ A. ” comptus. Also, there is a tooth on the columella of “ A. ” chauliodous that is absent in “ A. ” comptus.

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

ETYMOLOGY. — From the Greek chauliodous (having a prominent tooth), in reference to the conspicuous tooth on the columella that distinguishes this species from others with a similar shell morphology.