Phaedusa pahangensis (Laidlaw, 1929)
“Resembles in size and general appearance C. cornea from Java, but has fewer whorls, and a much more quadrate aperture. In fact the upper lip in this species is less oblique than in any of the Malaysian species which I have been able to examine, or of which I have seen figure.” (Laidlaw, 1929)
“In his description Laidlaw did not mention more than 3 plicae palatals below the principalis. He compared his shell to Acrophaedusa cornea Phil. From Java, which is certainly not correct. Relationship with Ph. filicostata Stol. On other hand is clear.” (Loosjes, 1953)
Laidlaw (1929) original descriptions on Clausilia pahangensis – “Shell elongately fusiform, light brown, probably rather corneous when living, with 8 ½ whorls. Protoconch small, smooth, the later whorls being closely and rather strongly striate, without trace of spiral sculpture. Suture well marked, paler; last whorl very slightly narrower than the preceding one. Mouth rather quadrate, light brown within, peristome white. Parietal lamella nearly vertical, reaching to the lip, columellar lamella rather more deeply placed, and ascending rapidly. The plicae are difficult to distinguish owing to the strong sculturing of the surface of the shell. There appear to be three palatal plicae below the plica principalis; of these three the middle one is the shortest.”
Loosjes (1953) descriptions on Phaedusa pahangensis – “Shell small, but comparatively wide, fusiform, rather solid, purplish- to grey-brown, dull, not transparent. Spire quickly broadening with straight or convex lateral outlines. Whorls 8 ½-9 ½, rather convex, sculptured with numerous transverse, strong, wavy striae (about 10 to the mm on the whorl above the aperture), they are but slightly coarser on the neck and are somewhat wider apart there. A distinct thread of the same colour as the shell runs below the shallow suture in most of the specimens. Nuclear whorls 2 ½, smooth. In a side view the neck curves regularly and slowly down to the base of the aperture. The penultimate whorl is broadest. Aperture quadrangular, egg-shaped, light-brown within. The sinulus is separated from the rest of the aperture only by the superior lamella. The plane part runs parallel with the axis of the shell. The peristome is continuous, white, projecting and broadly reflexed; the upper margin is clear of the preceding whorl; it is not bent where it is touched by the lamella superior. The descent of the outer peristomal edge from the sinulus is almost straight; the parieto-columellar margin curves down regularly, forming ¼ of the circumference of a circle. The base of the peristome is regularly curved. Lamella superior is of moderate height, reaching the margin; its inner end is clear of the lamella spiralis and approaches the lamella inferior. The outer end of the spiral lamella lies at the left side, to the left og the superior lamella. The lamella spiralis ascends as a high fold. Lamella inferior ends low, half way up the columellar side of the aperture; it does not reach the margin. It increases in height when curving upward into the aperture; in a full front view its edge is not completely horizontal when disappearing from sight. The inner ends of the lamellae have not been studied. When looking into the aperture it is hardly possible to see the inner side of the base of the inferior lamella. Lamella subcolumellaris is not or scarcely visible when seen from below and from the left side into the aperture. The closing apparatus lies between the dorsal and the right side. The plica palatalis principalis runs from the dorsal side to the right side; it is about ¼ whorl long. Below it we count 5 to 10 almost parallel plicae palatals. The longest are found at the top, near the plica palatalis principalis and at the bottom of small plicae, not interrupted in the middle of the whorl. Exceptionally some very small plicae occur between the principal plica and the upper palatal plica. These plicae and the end of the lamella subcolumellaris (between the lowest plica and the umbilicus) are not easily discernible through the shell. The plate of the clausilium is broadest at 1/3 from the slightly thickened top. Its dimensions are: long 2.1m width 1.4 mm.”
Clausilia pahangensis – “Length, 16.5 mm.; diam. max., 3.75 mm.; apert. alt., 3.75 mm.; apert. lat., 3.25 mm.” (Laidlaw, 1929); Phaedusa pahangensis – “Length of the shells: 16.8 t 19.4 mm, diam. 3.7 to 4.5 mm; aperture; height 3.8 to 4.9 mm, width 3.0 to 3.8 mm.” (Loosjes, 1953)
Type locality – “Gunong Tahan, Pahang, 4000 feet, Padang Sebrang” leg. H. M. Pendlebury/Dec. 22, 1922 (Laidlaw, 1929)
Other localities – “Perhaps the Larut Hills, Perak” (Laidlaw, 1933); ‘Telom Valley, near Mount Siku, 1500 m” (Loosjes, 1953); ‘Mount Brinchang, 1500-1800 m” (Loosjes, 1953); ‘Kuala Terla, Telom Valley, 1300-1700 m” (Loosjes, 1953)