Plectostoma kitteli (Maassen, 2002)

Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin & Schilthuizen, Menno, 2014, A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina, ZooKeys 393, pp. 1-107 : 61-63

Plectostoma kitteli (Maassen, 2002) Figure 43, Appendix 11

Opisthostoma kitteli Maassen, 2002: 176, figures 35 & 36 (original description).

Type material.

Holotype: RMNH 92942(1) (seen). Paratypes: RMNH 92956(>25) (Seen), V 12697(9) (Seen).

Other examined materials.

BOR 1697(>10). YSC.

Diagnosis.

Shares with Plectostoma charasense , Plectostoma tohchinyawi , and Plectostoma klongsangensis the general shell form, in terms of apex, spire, and tuba shape, but differs by lacking thick spiral lines and basal constriction teeth.

Description.

Apex. Shape: distinctly convex.

Spire. Height: 2.9-3.0 mm. Width: 1.7-1.8 mm. Number of whorls: 5 5/8-5 3/4. Apical spire shape: oblong conical. Basal spire shape: conical. Whorl periphery: distinctly convex. Umbilicus: partially closed by tuba.

Constriction. Parietal teeth: two. Basal teeth: none.

Tuba. Coiling direction: type 2 and aperture visible in right lateral view. Tuba whorl length in proportion to spire last whorl: ca. 3/4-7/8. Proportion of tuba that attaches to spire: less than 2/3.

Aperture and peristome. Peristome: double peristomes. Outer peristome shape: similar to inner peristome, projected all around, except the posterior part, where the two lateral sides are slightly more projected than the anterior side.

Spiral lines. Thick lines: absent. Thin lines: present.

Radial ribs. Rib density: 5-6 ribs per mm. Rib intensity: thin. Shape: slightly curved. Inclination: orthoclin.

Distribution.

Type locality. Cave Pangian (local name Ngalau Pangian - 0°27'45"S, 100°45'8"E)

Distribution range. This species was also found at a limestone hill near Kampung Desa Gadut, West Sumatra (0°15'36"S, 100°44'16"E). This hill is located about 20 km from the type locality. In addition, a private collector (Yansen Chen, pers. comm.) also collected the same species at Tiangko cave, about 230 km from the type locality (Figure 18B). It therefore appears to have a wide distribution range in Sumatra. It may thus be expected that the limestone outcrops around the three hills mentioned, might support the same species.

Conservation status.

Data deficient. This species has only been recorded from three limestone hills in West Sumatra. The population status and actual distribution range of this species remain unknown. Nevertheless, concern is warrented, as the surroundings of the type locality and several other limestone outcrops in the same area are highly degraded.

Discussion.

There are large areas in the Northern and Western provinces of Sumatra that are covered by limestone hills (Verstappen and Genootschap 1973). Despite intensive malacological surveys in some of these areas (van Benthem Jutting 1959), no Plectostoma species was found until 1997. To date, Plectostoma kitteli is the only Plectostoma species found in Sumatra ( Maassen 2002).