Truncacteocina arata (Watson, 1883)

Valdés, Ángel, 2008, Deep-sea “ cephalaspidean ” heterobranchs (Gastropoda) from the tropical southwest Pacific, Mémoires du Muséum national d'Histoire naturelle 196, pp. 587-792 : 712-713

Truncacteocina arata (Watson, 1883)

Figs 60F, 61

Utriculus aratus Watson, 1883: 329 .

Synonym:

Acteocina oyamai Kuroda & Habe, 1954: 10 .

TYPE MATERIAL. — U. aratus : 2 syntypes BMNH 1887.2.9.2236-7 . — A. oyamai : not examined.

TYPE LOCALITY. — U. aratus : West of Cape York , off southwest point of Papua, Northern Australia, 9°59’S, 139°42’E, 51 m [Challenger: stn 188] . — A. oyamai : Japan.

MATERIAL EXAMINED. — Philippines. MUSORSTOM 2: stn Indonesia. KARUBAR:stn DW 28 , Kai Islands , 05°31’S, 132°54’E, DR 34, 13°28’N, 121°12’E, 155-167 m, 1 dd . — MUSORSTOM 448-467 m, 2 dd.

3: stn CP 87, 14°00’N, 120°19’E, 191-197 m, 1 dd; stn CP 100, North of New Caledonia. MUSORSTOM 4: stn DW 149, 19°08’S, 14°00’N, 120°18’E, 189-199 m, 2 dd; stn CP 101, 14°00’N, 163°23’E, 155 m, 1 dd; stn DW 187, 19°08’S, 163°29’E, 65-120 m, 120°19’E, 194-196 m, 13 dd (Fig. 60F); stn DR 102, 14°01’N, 1 dd.

120°18’E, 192 m, 7 dd; stn CP 139, 11°53’N, 122°14’E, 240- South of New Caledonia. CALSUB: pl 18, SW of Ile des Pins, 267 m, 2 dd. 22°46’S, 167°20’E, 270 m, 1 dd.

New Caledonia proper. LAGON: stn 830, Secteur de Poindimié , Loyalty Ridge. MUSORSTOM 6: stn DW 442 , 20°54’S, 167°17’E, 20°49’S, 165°19’E, 105-110 m, 1 dd . — BATHUS 1 : stn DW 654, 200 m, 1 dd .

Passe de Canala, 21°17’S, 165°57’E, 237-298 m, 12 dd; stn DW Vanuatu. MUSORSTOM 8: stn DW 1115, 15°10’S, 166°53’E, 674, Grande Passe de Touho, 20°49’S, 165°19’E, 105-110 m, 6 147-150 m, 1 dd.

dd; stn DW 677 , 20°49’S, 165°19’E, 96-109 m, 3 dd; stn DE 700, Fiji. MUSORSTOM 10: stn DW 1329 , Bligh Water, 17°19’S, Passe du Cap Baye, 20°57’S, 165°35’E, 160-222 m, 48 dd; stn 177°47’E, 102-106 m, 7 dd; stn DW 1464 , 18°09’S, 178°38’W, DW 706 , Passe SE de Ngoe , 21°42’S, 166°34’E, 247-252 m, 44 285-300 m, 1 dd; stn DW 1465 , 18°09’S, 178°39’W, 290-300 m, dd; stn CP 713, 21°45’S, 166°37’E, 250 m, 5 dd . — BATHUS 2 : 1 dd; stn DW 1498 , 18°41’S, 178°28’W, 300-307 m, 1 dd .

stn DW 717, Ile des Pins, 22°44’S, 167°17’E, 350-393 m, 1 dd Australia. The type material of U. aratus .

DISTRIBUTION. — Originally described from northern Australia, in 51 m (Watson 1883). Subsequently reported from Indonesia, in 132 m (Thiele 1925). Material herein collected in the Philippines, Indonesia, New Caledonia, Vanuatu and Fiji (Fig. 61), in 106-448 m.

DESCRIPTION. — Shell morphology. Length 5.5 mm, width 2 mm (largest specimen examined). Shell solid, oval, with nearly parallel sides (Fig. 60F). Body whorl very large; spire low, with 2-3 whorls, apex truncate. Whorls with angular shoulders. Suture deeply canaliculate. Umbilicus narrow, partially covered by an extension of the columella. Aperture almost as long as the shell, narrow, wider anteriorly, narrowing gradually towards the posterior end. Columellar margin thickened. Columella simple, with no folds. Sculpture of fine spiral grooves, crossed by faint axial lines. The spiral grooves near the anterior end of the shell are more conspicuous and separated from each other. Colour uniformly whitish.

Anatomy. Unknown. All shells collected lacked soft parts.

REMARKS. — Utriculus aratus was originally described from near Cape York, northern Australia, in 51 m (Watson 1883). Examination of the syntypes of this species revealed that they belong to the same species as the material here examined, collected from Fiji, Indonesia, New Caledonia, the Philippines and Vanuatu .

Acteocina oyamai , originally described from Japan by Kuroda & Habe (1954) and subsequently illustrated by Hori (2000b), is also very similar to Utriculus aratus and is here regarded as a synonym. Because Acteocina oyamai is the type species of Truncacteocina , Utriculus aratus is transferred to this genus pending anatomical information becoming available to determine whether Truncacteocina is a valid name.