Palaina motiensis, Heryanto & Mujiono & Laitupa & Nurinsiyah, 2023

Heryanto, Mujiono, Nova, Laitupa, Ibnu Wahab & Nurinsiyah, Ayu Savitri, 2023, Two species of Diplommatina and a new species of Palaina (Gastropoda: Cyclophoroidea: Diplommatinidae) from Moti Island, North Moluccas, Indonesia, Raffles Bulletin of Zoology 71, pp. 331-336 : 335

Palaina motiensis , new species

( Figs. 1 , 2c ; Table 1)

Diplommatina sp. 3 — Heryanto, 2011: 123.

Material examined. Holotype: specimen MZB.Gst. 22493 (D = 1.65 mm, H = 3.25 mm), Indonesia, North Moluccas, Moti Island, 480 m a.s.l., 0°27′42.8″N 127°24′52.5″E, coll. Heryanto, May 2010 . Paratypes: MZB.Gst. 22494/4, same data as for holotype .

Diagnosis. Palaina motiensis , new species is characterised by an ovoid, distant ribbed, sinistral shell with an operculum with an indistinct spiral ridge on the outer surface.

Description. Shell sinistral; ovoid with pointed top; with 5–5.5 angular whorls separated by deep suture; protoconch smooth; teleoconch with curved and distant ribs; denser ribs appear on angular part of penultimate whorl and on body whorl towards peristome; without distinct spiral striae between ribs; whitish or corneous; subtranslucent; body whorl angular near lower margin; aperture rounded; upper insertion of peristome distinctly ascending towards aperture; insertions of peristome connected by a distinct callus; peristome expanded, thickened, but not doubled; without lamellae or folds. Shell height 3.0– 3.3 mm, shell diameter 1.6–1.9 mm.

Remarks. Two known Palaina species, P. tanimbarensis Greķe, 2017 and P. silvicultrix Greķe, 2017 , have a similar shell with this new species. Palaina tanimbarensi s differs by the expanded and doubled peristome, as well as the protruding ribs. Moreover, it was recorded in Yamdena I., which is located in the far south, approximately 974 km from Moti I. and separated by deep sea. Most of the known taxa (98%) in this region are site endemic ( Greķe, 2017). Thus, it is unlikely that the two species are the same. Palaina silvicultrix from Waigeo, West Papua, located ~ 366 km away and separated by the Halmahera Sea, has a more expanded and doubled peristome, as well as denser ribs compared to this new species.

Habitat. The specimen was found in secondary forest, in a nutmeg plantation, on a large boulder of volcanic rock covered with herbaceous layers and moss, and in between leaf litter. The species was found at the elevation range of 400 to 500 m a.s.l.

Distribution. Palaina motiensis , new species is endemic to Moti Island, where it has been found so far only on the island.

Etymology. The species Palaina motiensis is named after the type locality, Moti Island where the holotype was found.

Figures

Fig. 1. Map of Moti I. in the North Moluccas Archipelago, with the insertion of the North Moluccas in Indonesia and the studied area in Moti I.

Fig. 2. Shells of Diplommatinidae described from Moti I. a, Diplommatina moluccensis Greķe, 2017, (MZB.Gst. 22496). b, Diplommatina radiiformis Preston, 1913, (MZB 22497). c, Palaina motiensis, new species (Holotype, MZB 22493). Scale bars = 1.0 mm.