Maxacteon sagamiensis (Kuroda & Habe, 1971)

Valdés, Ángel, 2008, Deep-sea “ cephalaspidean ” heterobranchs (Gastropoda) from the tropical southwest Pacific, Mémoires du Muséum national d'Histoire naturelle 196, pp. 587-792 : 608-609

Maxacteon sagamiensis (Kuroda & Habe, 1971)

Figs 8F-H, 9

Leucotina sagamiensis Kuroda & Habe in Kuroda et al., 1971: 271, 435, pl. 113, fig. 18.

TYPE MATERIAL. — NSMT MoR 19019 .

TYPE LOCALITY. — Sagami Bay , central Honshu, Japan .

MATERIAL EXAMINED. — Philippines. MUSORSTOM 2: stn DR 33, 13°32’N, 121°07’E, 130-137 m, 1 dd .

DISTRIBUTION. — Reported from Japan, in 16-200 m (Hori 2000a). Single specimen herein collected from the Philippines (Fig. 9), in 130-137 m.

DESCRIPTION. — Shell morphology. Length 5.5 mm, width 4 mm (only specimen examined). Shell solid, elongate, with convex sides (Fig. 8F). Body whorl large, about 2/3 of the shell length. Spire long, conical, with 2 long whorls. Suture channeled. Protoconch globose, about 1 whorl and 700 Μm in diameter (Fig. 8G). Umbilicus narrow, covered by an extension of the columellar margin. Aperture short and narrow, wider anteriorly, about 3/4 of the body whorl length. Columellar margin thickened, short and straight, with no folds. Sculpture of a number of punctuated spiral grooves (Fig. 8H). The punctuations are large, oval, partially fused to the next one within each groove. The grooves are separated by gaps that are as wide as the grooves. Colour uniform dirty white.

Anatomy. Unknown. All shells collected lacked soft parts.

REMARKS. — Leucotina sagamiensis was originally described from Sagami Bay, Japan (Kuroda & Habe in Kuroda et al. 1971) as a pyramidellid. Higo et al. (2001) illustrated the holotype and Hori (2000a) transferred it to Punctacteon . The material from the Philippines here examined is very similar to the original description by Kuroda & Habe in Kuroda et al. (1971) and the redescription by Hori (2000a) and it is assigned to this species. Punctacteon sagamiensis is here transferred to Maxacteon , while realizing that this placement may be revised in the light of future study.

The most similar species to M. sagamiensis in shell morphology is “ Acteon ” chauliodous n. sp. (see below) but it differs from M. sagamiensis in having a more elongate shell and aperture, longer columella with a denticle, and more separate spiral grooves.