Retusa diaphana, Valdés, 2008

Valdés, Ángel, 2008, Deep-sea “ cephalaspidean ” heterobranchs (Gastropoda) from the tropical southwest Pacific, Mémoires du Muséum national d'Histoire naturelle 196, pp. 587-792 : 733-735

publication ID	978-2-85653-614-8
persistent identifier	https://treatment.plazi.org/id/03D087B2-FF76-BEBA-FF01-7248F6D0FE11
treatment provided by	Felipe
scientific name	Retusa diaphana
status	sp. nov.

Treatment

Retusa diaphana View in CoL n. sp.

Figs 73C, D, 74

TYPE MATERIAL. — Holotype MNHN 20407 and 9 paratypes MNHN 20408-20409, 24 paratypes LACM 3001 View Materials .

TYPE LOCALITY . — Fiji, 17°08’S, 178°59’W, 402-410 m [ BORDAU 1 : stn DW 1423 ] GoogleMaps .

MATERIAL EXAMINED. — Fiji. MUSORSTOM 10: stn CP 1341, 455- 515 m, 62 dd; stn DW 601 , 13°19’S, 176°17’W, 350 m, 24 dd, Bligh Water , 16°53’S, 177°44’E, 500-614 m, 3 dd, paratypes paratypes ( LACM 3001 View Materials ); stn DW 604 , 13°21’S, 176°08’W, 415- MNHN 20409 View Materials GoogleMaps ). — BORDAU 1 : stn DW 1423 , 17°08’S, 178°59’W, 420 m, 4 dd GoogleMaps .

402-410 m, 7 dd, holotype ( MNHN 20407; Figs 73C, D) and pa- Tonga. BORDAU 2: stn DW 1571, N of Ha‘apai Islands, 19°42’S, ratypes ( MNHN 20408). 174°32’W, 389-418 m, 1 dd.

Wallis Island. MUSORSTOM 7: stn DW 523, 13°12’S, 176°16’W,

DISTRIBUTION. — Collected from Fiji, Tonga and Wallis Island (Fig. 74), in 350-500 m.

DESCRIPTION. — Shell morphology. Length 2.5 mm, width 1.9 mm (holotype). Shell fragile, oval, with nearly parallel sides (Fig. 73C). Only 1 whorl visible, forming nearly the entire shell, except for the top of the spire, where 3 whorls are visible. Apex flat, slightly convex, not umbilicate (Fig. 73D). Protoconch globose, about 0.8 whorl and 150 Μm in diameter (Fig. 73D). Anterior end of the shell rounded. Aperture almost as long as the shell, wider anteriorly and narrowing gradually at about 1/3 of its length. Columellar margin slightly thickened. Columella simple, with no folds. Umbilicus closed. No sculpture. Colour uniformly translucent whitish.

Anatomy. Unknown. All shells collected lacked soft parts.

FIG. 73. Shell morphology and anatomy of species of Retusa Brown, 1827 . A, Retusa sulcata (Watson, 1883) , gizzard plates, New Caledonia, MUSORSTOM 4 stn DW 149, scale bar = 100 Μm. B, Retusa crispula (Watson, 1883) , gizzard plates, New Caledonia, MUSORSTOM 4 stn CC 175, scale bar = 100 Μm. C, Retusa diaphana n. sp., holotype MNHN 20407 (2.5 mm), ventral view, Fiji, BORDAU 1 stn DW 1423; D, same shell, posterior view. E, Retusa insolita n. sp., holotype MNHN 20410 (7 mm), ventral view, New Caledonia, BIOCAL stn DW 53; F, same shell, posterior view.

REMARKS. — Retusa diaphana differs from other Indo-Pacific species of Retusa . The most similar species in shell morphology is Retusa eumicra Crosse, 1865 , from southern Australia, which has a more elongated shell.

This species is placed in the genus Retusa because of the morphological similarities of the shell to those of some other species of the genus, pending the availability of anatomical information.

ETYMOLOGY. — From the genus name Diaphana Brown, 1827 , in reference to the resemblance of the shape of the shell to shells of this genus.