Platycochlium sarawakense Laidlaw, 1950
“Platycochlium sarawakense is variable in several characters. Particularly in the Penrissen area S. of Kuching populations occur which differ from the type specimen in the following characters: shell distinctly elliptic (not orbicular) in apical view; umbilical folds present, although very inconspicuous in all cases (never growing out into distinct lamellae as in P. saulae); margin of umbilicus only partly (not entirely) crenulaled. Specimens which arc intermediate between these populations and the type specimen are frequently found. Such specimens show only one or two of the above mentioned characters, in all possible combinations. Distinction of subspecies is therefore impossible. Juvenile specimens of P. sarawakense do not have a peripheral keel.” (Vermeulen, 1991)
Dance (1950) descriptions on Platycochlium sarawakense – “Shell elliptical viewed from above and below; base flattened, spire broadly dome-shaped; translucent, colourless, glossy. Whorls 5, gently sloping, suture shallow; last whorl encircled by a strong carina. Spire-whorls ornamented with irregularly-spaced, weak collabral ribs; underside of the last whorl smooth with the exception of the area around the umbilicus. Varices usually 5 in number (but varying according to the stage of growth) the last-formed varix being very conspicuous. Umbilicus wide and deep, elliptical or almost circular. Aperture trigonal, with a thickened and reflected peristome which is attached to the previous whorl; parietal lamella originates a short way inside the last whorl and projects at its posterior point of attachment where it is thickened and bifurcate. Upper lip thickened, projecting and inflected to form a distinct tooth; 2 deep-seated palatal teeth, the upper minute and ridge-like, the lower rounded and projecting towards the parietal lamella.”
Vermeulen (1991) descriptions on Platycochlium sarawakense – “Shell low conical 10 almost discoidal in frontal view, sometimes distinctly elliptic in apical view. Whorls 3½-4 3/8, slightly convex above and below the periphery; periphery distinctly keeled; suture moderately impressed; top whorls smooth; next whorls with 4-5 varices next to the peristome, each varix preceded by a number of ribs, the ribs crossed by a fine, concentric striation. Umbilicus wide, approximately orbicular to elliptic, inner margin of the whorls entirely crenulated or only so near the varices; last whorl without umbilical lamellae or with two opposite, very inconspicuous ones, which not or hardly cover the umbilicus. Aperture subtriangular with the parietal side concave. Peristome reflected, with a knob-like thickening on the palatal side, above which a shallow sinus; usually with a small notch in the edge between basal and parietal side. Teeth four: one angularis, a sinuous lamella starting deep inside and ending in a thick knob; one short basalis, ending as a small thickening of the peristome; two deeply set palatales, Ihe upper one hidden behind the palatal swelling of the peristome.”
Platycochlium sarawakense – “Shell height – 1.0-1.2 mm; Shell width – 2.4-2.6 mm.” (Dance, 1970); Platycochlium sarawakense – “Height 1.1-1.5 mm; largest diameter 2.3-2.9 mm; smallest diameter 1.9-2.5 mm; height of aperture 0.6-0.8 mm; width of apenure 0.7-1.2 mm.” (Vermeulen, 1991)
Type localities – “Gunong Kapor, 3 miles SW of Bau.” (Dance, 1970)
Other localities – “Gunung Kawa; 2 miles S of Bau.” (Dance, 1970); Gunong Doya, 2 miles SE of Bau.” (Dance, 1970); Bra-ang Mountain, 22 miles S of Kuching.” (Dance, 1970); hill 1 mile of Pankalan Ampat, 25 miles S of Kuching.” (Dance, 1970); Wah Mountan, 23 miles S of Kuching.” (Dance, 1970); Saak Mountain, 1 mile W of Begu, 24 miles S of Kuching.” (Dance, 1970); Gayu Mountain, 23 miles S of Kuching.” (Dance, 1970); 2 small hills by side of Simanggang Road, 18 ½ and 21 mile SSE of Kuching.” (Dance, 1970); hill 8 miles SW of Serian.” (Dance, 1970); Gunong Selabor, about 16 miles SSW of Serian.” (Dance, 1970); “G. Jambusan 4 km SE. of Bau” (Vermeulen, 1991); “Kpg. Beratok along road Kuching-Serian” leg. Auffenberg (Vermeulen, 1991); “Kpg. Tiang Bekap 10 km SSW. of Kpg. Beratok” leg. De Vogel (Vermeulen, 1991); “Kpg. Segur Benuk, mile 21 Penrissen Road” leg. De Vogel (Vermeulen, 1991); “7.5 km WNW. of Kpg. Piching, near Serian” leg. Vermeulen (Vermeulen, 1991); Lobang Batu 12.5 km S. of Tebakang” leg. Vermeulen (Vermeulen, 1991)
Gua Kapur, Bau, Sarawak, Malaysia.
“Calcicole.” (Vermeulen, 1991)