Plectostoma salpidomon (van Benthem Jutting, 1952)

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 : 60-61

Plectostoma salpidomon (van Benthem Jutting, 1952) Figures 17A, 42, Appendix 13

Opisthostoma salpidomon van Benthem Jutting, 1952: 42, figure 21 (original description).

Opisthostoma salpidomon van Benthem Jutting, van Benthem Jutting (1961: 39).

Type material.

Holotype: ZMA 136045(1) (Seen). Paratypes: ZMA 136046(>25) (Seen), ZMA 136047(2) (Seen), ZMA 136048(>10) (Seen).

Other examined materials.

ZMA 162137(>25), BOR 459(1), BOR 5539(>10), BOR 5540(>10), BOR 5541(5), BOR 5542(>25), BOR 5569(>25), BOR 5611(1), V 8171(4), V 8658(>25), V 8706(6), V 9116(7), V 9292(3).

Diagnosis.

Shares with Plectostoma laemodes the general shell form, in terms of apex, spire, and tuba shape, but differs by having a tuba that attaches partly to the spire.

Description.

Apex. Shape: distinctly convex.

Spire. Height: 2.5-2.8 mm. Width: 1.5-1.7 mm. Number of whorls: 4 5/8-5 1/4. Apical spire shape: depressed conical. Basal spire shape: ovoid. Whorl periphery: moderately to distinctly convex. Umbilicus: completely or 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: prosoclin.

Distribution.

Type locality. Gua Bama, Pahang (4°11'37"N, 101°58'2"E) (Figure 18B).

Distribution range. Plectostoma salpidomon can be found in many limestone hills in the valley in between the Titiwangsa, Tahan and Benom mountain ranges (Figure 18B).

Conservation status.

Least concern. Plectostoma salpidomon has a wide distribution range. Living populations have been recorded in many limestone hills and some of these are in protected areas.

Discussion.

See discussion under Plectostoma laemodes .