Palaina subregularis (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 : 40-41

Taxon classification Animalia Mesogastropoda Diplommatinidae

Palaina subregularis (Mousson, 1870) Figs 86-92

Diplommatina subregularis Mousson 1870, Journal de Conchyliologie, 18: 181, pl. VIII, fig. 3. Type locality: "Nagara, petite île située près de la côte sud de Viti-Levu".

Diplommatina graeffei Möllendorff 1897, Nachrichtsblatt der deutschen malakozoologischen Gesellschaft, 29 (1/2): 44 [name attributed by Möllendorff to Mousson]. Type locality: Vitilevu. New synonym.

Palaina (Palaina) subregularis , - Kobelt 1902, Cyclophoridae : 405.

Diancta (Diancta) graeffei , - Kobelt 1902, Cyclophoridae : 420.

Type data.

No type specimens of Diplommatina subregularis could be traced in MNHN or in ZMZ. Under the name Diplommatina subregularis , the Mousson collection houses the lot ZMZ 526677 which, according to the handwritten label, originates from "Viti Levu, Graeffe 1872". Although identified by Mousson himself as his Diplommatina subregularis , this lot is not type material, because it reached Mousson two years after the description of the taxon, and it does not originate from the type locality. From the same locality "Viti Levu", four specimens in SMF 105079/4 (coll. Möllendorff ex Mousson, also as Diplommatina subregularis ), had been identified as “cotypes” by A. Zilch. It is highly probable that these specimens also come from ZMZ 526677, and thus were not originally part of the type series. Moreover, SMF 105079/4 consists of three shells that do match with " subregularis " in the sense of Mousson, and one that does not, but is Palaina godeffroyana . In order to stabilize the application of this name, we here designate a neotype from ZMZ 526677, because the specimens from this lot match the description of Mousson very well. Neotype: subregularis ZMZ 526677a, Viti Levu, coll. Mousson ex Graeffe 1872 (Fig. 86).

Diplommatina graeffei : lectotype, designated by Zilch (1953: 17, pl. 6 fig. 89), SMF 104903/1, Fiji, Viti Levu, coll. Möllendorff ex Mousson. The name graeffei had already been used by Mousson in his collection (ZMZ 526702/many, " Diplommatina graeffei Mss., Viti Levu (Graeffe)"), but had remained a manuscript name. The lectotype of graeffei matches the shells in this lot so well that the SMF specimen most probably originates from this lot; however, there is no evidence that Möllendorff ever saw the specimens in the Mousson collection when he published the name Diplommatina graeffei , and the specimens in ZMZ 526702 are not regarded by us as paralectotypes.

Material.

SMF 105079/4, Fiji, Viti Levu, coll. Möllendorff ex Mousson; Viti Levu, Voli Voli limestone outcrop, 10-30 m, secondary open forest, -17.3374 178.1831, leg. Bouchet, Warén & Dayrat, 18.02.1999, MNHN/8; Viti Levu, limestone outcrop SE of Nambukulevu, 230 m, rainforest, -18.1366 177.8149, leg. Bouchet, Warén & Dayrat, 20.02.1999, MNHN/6; Viti Levu, Qalimare karst, Toga village, 30-130 m, dry forest, -17.9953 177.5768, leg. Bouchet, 21.08.1998, MNHN/255, NMBE 516896/20; Viti Levu, Tuvu karst, 50 m, dry forest, -17.9332 177.7067, leg. Bouchet, 23.08.1998, MNHN/172, NMBE 516897/20.

Diagnosis.

Shell sinistral, elongate oval, teleoconch whorls with widely spaced ribs, brown axial flames or blotches between the ribs, aperture circular, bulb reduced, columella a broad lamella, basally with columellar tooth.

Description.

Shell sinistral, elongate oval, eroded shells purely white, well preserved specimens with a pattern of brown axial flames or blotches between the ribs; protoconch acute, granulated; last whorl not constricted, slightly ascending; bulb reduced, demarcated by a faint bulb lamella; umbilicus closed, periomphalum narrow; sculpture of teleoconch whorls with widely spaced ribs, ribbing pattern above the aperture somewhat denser; aperture circular, sometimes with a double lip demarcated by a brown line, adhered to the last whorl; oblique view into the aperture revealing a strong columellaris; internally, columella forming a broad lamella extending towards the interior of shell, basally forming a columellar tooth.

Operculum corneous, outer surface with several concentric lamellae and a single, short raised lamella; internal surface concave, smooth.

Measurements.

Neotype of subregularis (Fig. 86): H = 3.5; D = 1.71; PH = 1.24; PD = 1.26; W = 7; lectotype of graeffei (Fig. 89): H = 2.7; D = 1.35; PH = 0.99; PD = 0.89; W = 7.

Distribution

(Fig. 170). Quite widespread on Viti Levu.

Remarks.

After a careful comparison of the lectotype of Diplommatina graeffei with the rest of the material attributed to Palaina subregularis , it was not possible to find any discriminating characters between the two taxa besides shell size, and we conclude that the former is a small specimen of the latter.

For a differential diagnosis, refer to Palaina flammulata sp. n., Palaina truncata sp. n., and Palaina parietalis sp. n.