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See discussion under Plectostoma christae.
Type locality. Tham Krachaeng, Thailand (6°12'50"N, 101°12'9"E). The location description in the original publication is not completely correct “(06°55'022"N, 101°12'160"E)” (Maassen 2001).
Distribution range. This species is only known from the type locality (Figure 18D).
ZMA 138438(1).
Shares with Plectostoma mengaburensis and Plectostoma dindingensis the general shell form, in the terms of apex, spire and tuba, but differs by having a single parietal constriction tooth.
Apex. Shape: moderately convex.
Spire. Height: 2.1–2.2 mm. Width: 1.6–1.7 mm. Number of whorls: 4 1/2–4 5/8. Apical spire shape: depressed conical. Basal spire shape: ovoid. Whorl periphery: moderately convex. Umbilicus: open.
Constriction. Parietal teeth: one. Basal teeth: none.
Tuba. Coiling direction: type 1 and aperture visible from back view. Tuba whorl length in proportion to spire last whorl: ca. 3/4. Proportion of tuba that attaches to spire: whole.
Aperture and peristome. Peristome: double peristomes. Outer peristome shape: same as inner peristome and uniformly projected all around, except the posterior part.
Spiral lines. Thick lines: present. Thin lines: present.
Radial ribs. Rib density: 8–9 ribs per mm. Rib intensity: thin. Shape: straight. Inclination: orthoclin.
Data Deficient.
Holotype: RMNH 81809(1) (Seen). Paratypes: RMNH 81810(2) (Seen).
Maassen (2001) original descriptions on Arinia panhai – “Shell dextral, conical, light brown, shining and transparent; with six moderately convex whorls, separated by a deep suture, and with a distinct spiral striation. The penultimate whorl slightly wider than the body-whorl. Radial ribs rather thin, increasingly higher and sharper on the lower whorls; on the penultimate whorl 6-8 ribs/mm, above the aperture 7-8 ribs/mm. The constriction consists of a transversal thickening all around, and of a small but distinct, longitudinal tubercle at the angular edge, just entering the transversal thickening. The tuba is 0.7 whorl long. Umbilicus widely open, eccentric, showing part of the penultimate whorl. Peristome doubled, the inner peristome only slightly protruding from the outer. The aperture is situated to the right of the middle of the previous whorl and clearly turned upwards. Operculum corneous, with a distinct spiral ridge on its outer surface.”
Arinia panhai – “H 2.5-2.7 mm; B 1.9-2.2 mm.” (Maassen, 2001)
Type locality – “Thailand, Yala province, Kachong Cave, 2.6 km off km 45.7 road 410 (Yala Bretong) (06°55’022”N, 101°12’160”E)” leg. J. & C. Hemmen (Maassen, 2001)
About location in original publication is not correct. The correct location should be Tham Krachaeng, 6°12'50.06"N 101°12'9.42"E.
