Plectostoma tohchinyawi Liew, Vermeulen, Marzuki & Schilthuizen, 2014

Plectostoma tohchinyawi Liew, Vermeulen, Marzuki & Schilthuizen, 2014

General description:

To be added

Conservation status:

To be added

Diagnostic description:

To be added

Morphology:

To be added

Taxon biology:

From a conchological point of view, this species is related to Plectostoma charasense. Both are thought to be affiliated with the Plectostoma species from North Borneo. Plectostoma tohchinyawihas a high conical spire, thick and projected radial ribs, and a long detached tuba. These are the typical characteristics for dozens of Plectostoma species in North Borneo. In addition, Plectostomatohchinyawi and Plectostoma charasense live on the five lenticular limestone outcrops that are the easternmost outcrops of the Malay Peninsula, thus closest geographically to Borneo (Figure 18B).

Distribution:

To be added

Wed, 2014-09-03 19:37 -- thorseng
Plectostoma tohchinyawi Liew, Vermeulen, Marzuki & Schilthuizen, 2014

General description:

Apex. Shape: distinctly convex.

Spire. Height: 2.1–2.4 mm. Width: 1.3–1.5 mm. Number of whorls: 4 7/8–5 3/8. Apical spire shape: oblong conical. Basal spire shape: conical. Whorl periphery: distinctly convex. Umbilicus: open.

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. 7/8–8/8. Proportion of tuba that attaches to spire: less than 1/2.

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 distinctly more projected than the anterior side.

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

Radial ribs. Rib density: 4–6 ribs per mm. Rib intensity: thick. Shape: slightly curved to single-humped. Inclination: prosoclin.

Conservation status:

Least concern. The only two limestone outcrops where this species was found are partially submerged in Southeast Asia’s largest man-made lake, Tasik Kenyir. Nonetheless, there is good forest cover around and on the limestone outcrops. Furthermore, these two hills are located in the Taman Negara Pahang, which is a prioritised protected area.

Diagnostic description:

Holotype: BOR 5649(1). Paratypes: BOR 5533(>10), BOR 5534(>10), BOR 5535(>10), V 8811(>25).

Distribution:

Type locality. Gua Bewah, Tasik Kenyir (4°51'3"N, 102°43'21"E).

Distribution range. To date, this species is only known to occur at two neighbouring limestone outcrops, namely, Gua Bewah and Gua Taat at the Southern part of Tasik Kenyir (Figure 18B).

Wed, 2014-09-03 19:37 -- thorseng
Plectostoma tohchinyawi Liew, Vermeulen, Marzuki & Schilthuizen, 2014

Diagnostic description:

Shares with Plectostoma charasense, Plectostoma kitteli, and Plectostoma klongsangensis the general shell form, in terms of apex, spire, and tuba shape, but differs by having both thin and thick spiral lines, and the left lateral side of outer peristome projected not more than twice the width of the right lateral side of outer peristome.

Wed, 2014-09-03 19:37 -- thorseng

Opisthostoma and Plectostoma (Family Diplommatinidae)

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Plectostoma tohchinyawi Liew, Vermeulen, Marzuki & Schilthuizen, 2014

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Plectostoma tohchinyawi Liew, Vermeulen, Marzuki & Schilthuizen, 2014

Plectostoma tohchinyawi Liew, Vermeulen, Marzuki & Schilthuizen, 2014

Plectostoma tohchinyawi Liew, Vermeulen, Marzuki & Schilthuizen, 2014

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Plectostoma tohchinyawi Liew, Vermeulen, Marzuki & Schilthuizen, 2014

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