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 : 612-614

“ Acteon ” laetus Thiele, 1925

Figs 10G, H, 11B, 12

Acteon laetus Thiele, 1925: 259 , pl. 30, fig. 12.

TYPE MATERIAL. — Holotype MNHB.

TYPE LOCALITY. — Zanzibar, Tanzania, 5°27.9’S, 39°18.8’E, 463 m [ Valdivia : stn 245] .

FIG. 11. Shell sculpture of species of “ Acteon ”. A, “ Acteon ” fortis Thiele, 1925 , sculpture of shell, New Caledonia, MUSORSTOM 6 stn DW 442, scale bar = 500 Μm. B, “ Acteon ” laetus Thiele,1925 ,sculpture of shell, New Caledonia, BATHUS 4 stn DW 914,scale bar = 100 Μm. C, “ Acteon ” editus n. sp., sculpture of paratype MNHN 20301, Tonga, BORDAU 2 stn DW 1553, scale bar = 100 Μm. D, “ Acteon ” buccinus n. sp., sculpture of paratype MNHN 20283, Coral Sea,MUSORSTOM 5 stn 346, scale bar = 100 Μm. E, “ Acteon ” ringiculoides n. sp., sculpture of paratype MNHN 20323, New Caledonia, SMIB 8 stn DW 166, scale bar = 100 Μm. F, “ Acteon ” boteroi n. sp., sculpture of paratype MNHN 20281, Tonga, BORDAU 2 stn CP 1640, scale bar = 100 Μm.

MATERIAL EXAMINED. — North of New Caledonia. BATHUS 169°48’E, 685-715 m, 1 dd; stn DW 794 , 23°48’S, 169°49’E, 4: stn DW 914 , Grand Passage, 18°49’S, 163°15’E, 600-616 m, 1 751-755 m, 1 dd .

dd (Figs 10G, H, 11B). Wallis Island. MUSORSTOM7: stn DW 523, 13°12’S, 176°16’W, New Caledonia proper. BATHUS 1: stn DE 697, Passe de Hieng- 455-515 m, 1 dd; stn DW 604, 13°21’S, 176°08’W, 415-420 m, 1 hène, 20°34’S, 164°58’E, 570-650 m, 1 dd. dd; stn DW 608, 13°22’S, 176°08’W, 440-458 m, 1 dd.

Loyalty Ridge. BATHUS 3: stn DW 790, Mont J, 23°49’S,

DISTRIBUTION. — Originally described from the western Indian Ocean. Material herein collected in New Caledonia and Wallis Island (Fig. 12), in 420-751 m.

DESCRIPTION. — Shell morphology. Length 3 mm, width 1.5 mm (holotype). Shell solid, elongate, with convex sides (Fig. 10G). Body whorl large, about 3/4 of the shell length. Spire short, conical, with 2-3 short whorls. Suture channeled. Protoconch globose, about 1 whorl and 500 Μm in diameter (Fig. 10H). Umbilicus closed. Aperture short and narrow, wider anteriorly, about 3/4 of the body whorl length. Columellar margin slightly thickened, with no folds or teeth. Sculpture of several punctuated spiral grooves (Fig. 11B). The punctuations are small, regularly oval, and separated from each other within each groove. The grooves are separated by gaps that increase in width towards the posterior end of the spire. The posterior 1/3 of the spire has no grooves, with the exception of 2 wide grooves, composed of very elongate and compressed punctuations situated next to the suture and close to each other. Colour uniformly whitish.

Anatomy. Unknown. All shells collected lacked soft parts.

REMARKS. — The material here examined matches the original description of Acteon laetus , originally described from the western Indian Ocean (Thiele 1925). Because the anatomy of the type material and the specimens here examined is unknown, I prefer to leave this species provisionally in “ Acteon ” until more material becomes available.

FIG. 12. Collection localities of species of Bathyacteon n. gen. and “ Acteon ” in the southwest Pacific: °, Bathyacteon aequatorialis (Thiele, 1925) . Z, “ Acteon ” fortis Thiele, 1925 . •, “ Acteon ” laetus Thiele, 1925 .