Palaina tuberosa (Mousson, 1870)

Neubert, Eike & Bouchet, Philippe, 2015, The Diplommatinidae of Fiji - a hotspot of Pacific land snail biodiversity (Caenogastropoda, Cyclophoroidea), ZooKeys 487, pp. 1-85 : 41-42

Taxon classification Animalia Mesogastropoda Diplommatinidae

Palaina tuberosa (Mousson, 1870) Figs 93-94

Diplommatina tuberosa Mousson 1870, Journal de Conchyliologie, 18: 185. Type locality: "Viti Levu (Vai-Loba) Südküste” [Vaini-Loba, south coast of Viti Levu].

Palaina (Palaina) tuberosa , - Kobelt 1902, Cyclophoridae : 406.

Type material.

Lectotype MNHN IM-2000-26707 [number of specimens not originally mentioned; the original specimen deposited in the collection of Journal de Conchyliologie is herewith designated as lectotype].

Material.

ZMZ 526687/3, "Viti Levu (Vai-Loba) Südküste”, coll. Mousson ex Graeffe 1872; ZMZ 526689a/1, Viti Levu, “Tatatan”, coll. Mousson ex Graeffe, 1872 [identified by Mousson as " Diplommatina martensi "].

Diagnosis.

Shell sinistral, small, bulb well developed, whorls widely ribbed, area above aperture fine and densely ribbed, labial callus weak, columella obliquely twisted, truncate with a thick bi-lobed tooth, parietalis a long slightly raised lamella.

Description.

Shell sinistral, small, broadly oval, faint yellowish; protoconch acute, granulated; last whorl not constricted, slightly ascending; bulb well developed; umbilicus closed, periomphalum narrow; sculpture of teleoconch whorls with widely spaced ribs, area above the aperture with fine and densely arranged ribs; aperture circular, simple, adhered to the last whorl; aperture with a weak labial callus, two small ear-like processes on the upper edges of the peristome; by oblique view into the aperture columellaris visible; internally, columella obliquely twisted, truncate in the lower half forming a thick bi-lobed tooth; parietum with a long slightly raised parietalis in front of the bulb.

Operculum unknown.

Measurements.

Lectotype (Fig. 93): H = 2.93; D = 1.68; PH = 1.11; PD = 1.21; W = 6.

Distribution.

Vaini-Loba (or Vai-Loba?) on the southern coast of Viti Levu (modern name not identified); not found during the 1998-99 field work.

Remarks.

Palaina tuberosa can easily be confused with Palaina tuberosissima sp. n., which is similar in shell size and shape. Palaina tuberosa differs from it by having the dense ribbing pattern of the area above the aperture, the weak labial callus, and the reduced ear-like processes on the peristome. In the internal lamellar system, Palaina tuberosa has only a bilobed columellar tooth, its parietalis is not spatulate, and a palatalis and second columellaris are missing altogether.