Pseudoplecta bijuga bijuga (Stoliczka, 1873)
“The height of the shell is very variable, but the increase of the whorls is very nearly quite constant. The upper convexity of increase of the whorls is very nearly quite constant. The upper convexity of the whorls also slightly varies; the sides of the spire are generally nearly straight, more rarely conspicuously convex; occasionally the peripherial keel is somewhat projecting above the suture. The ornamentation is characteristically that of Rotula, reticulately sculptured above, nearly smooth below. The transverse ribs on the upper surface are traversed by fine spiral lines, which generally only produce a slight undulation in the direction of the ribs, sometimes, however, a fine granulation is formed. As regards form, the present species very closely resembles the Burmese R. anceps, (Gould), and also the South Indian R. shiplayi, the first has, however, the upper costulation very fine and no spiral striae, while the latter has both much stronger developed, producing a granular surface, and the shell is also more solid. The third very closely allied species is R. indica, differing principally by a greater with of the last whorl, and also by a stronger sculpture.” (Stolizcka, 1873)
“Cette espèce est par sa forme très voisine de l’H. sakaya, mais elle s'en distingue par sa taille, par sa grande fragilité et sa coloration. L'ouverture dans 1'H. Pataniensis est presqu'aussi longue que large, tandis que celle de l’H. sakaya est beaucoup plus longue. L’H. pataniensis présente un péristome droit, tandis que l’H. Sakaya en possède un légèrement réfléchi et garni d'un léger bourrelet.” (Morgan, 1885)
“Certainly of the same group as the last species, and, so far as can be judged from the figure, not very different from E. anceps, Gld., Tenasserim.” (Möllendorff, 1891)
Stolizcka (1873) original descriptions on Rotula bijuga – “R. depresse conoidea et suborbiculata, vel late conica, angustissime umbilicata, tenui, cornea, pallide succinea; anfractibus 5.5 ad 6.5, sutura simplici, supra rare filiforme marginata, junctis, lente accrescentibus, in superficie superiore convexiusculis, costulis transverses obliquis, confertis, striis spiralibus confertissimis ac plus minusve distinctis intersectis, crispatulis seu subgranulosis, ornatis; ultimo ad peripheriam acute carinato, ad basin modice inflato, nitido, sublaevigato, striis incrementi radiantibus atque alteris spiralibus sub-obsoletis notato, medio cancaviusculo; aperture angulatim semilunari, paulum oblique, labio tenuissimo vix distinguendo, labro ad marginem tenui, neque expanso, neque incrassato, ad insertionem umbilicalem brevissime reflexo instructa.”
Morgan (1885) original descriptions on Macrochlamys pataniensis – “Macrochlamys testa dextrorsa, complanata translucida, cornea, vix umbilicata, laeviter striata, carinata usque ad aperturam, 5 anfractibus composita, parte superiori anfractibus complanatis et parte inferiori rotundatis; sutura lineata, facile apparenti, aperture obliqua, elliptica, aute ultime anfractu largiter incisa, labro recto et tenui.”
Morgan (1885) French descriptions on Macrochlamys pataniensis – “Coquille; Dextre, aplatie, très peu ombiliquée, très finement striée suivant des parallèles aux lignes de croissance, carénée, carène se prolongeant jusqu'à l'ouverture, spire formée de 5 tours aplatis à la partie supérieure et renflés à la base. Suture des tours linéaire, bien nettement marquée; ouverture oblique, ovale, très fortement échancrée par l'avant-dernier tour; péristome droit et aminci. Couleur; Cette coquille est translucide, d'un blond corné régulièrement réparti sur tout le test."
“The animal of the Penang species, when fully extended, equals in length about twice the longer diameter of the shell; back roundly flattened above, foot posteriorly obtusely ridged, terminating with a large gland which is superseded by a small horn; pedal row very distinct and the edge of foot below obliquely striated. The general colour of the body is pale or livid grey, with a general reddish tinge when full grown. A pale yellow (in young), or more or less distinctly cinober red (in adults), stripe extends along the centre of the back an the superior ridge of the foot, the former is bounded on each peduncle and continuing to the mantle, and below this stripe there is again a yellowish or red line. The posterior red band is only edged with black. The sides of the foot, both anteriorly and posteriorly, are more or less distinctly variegated with impure black and tinged with red; front of head between the two pedicles and tentacles with a black spot; pedicles and tentacles generally greyish, the latter with a reddish tinge, and with pale, rather large, globular tips, the former with a black ring at the base where the longitudinal black bands begin.” (Stolizcka, 1873)
“The mantle is moderately thickened. The right shell lobe is entirely obsolete, or only inicated by a very slight extension of the edge, a short distance below the upper angle of the aperture of the shell. Sole of foot divided by a longitudinal groove. The right neck lobe is large and extends as a moderately broad fringe to near the retractor muscle where it terminates with a free end. The left neck lobe is smaller with a linguiform free outer end. The left outer edge of the mantle is externally also entire, like the right one, but about the middle of the basal portion it has internally a distinct lobe, about 2 mm in length, which in its situation strictly speaking lies between the shell and the neck lobe; but as it becomes reflected with its edge over the shell, it has to be regarded as the representant of the left shell lobe; The lower portion of the left neck lobe have a large black spot, in continuation of the lateral black bands of the back.” (Stolizcka, 1873)
“The jaw is semilunar, perfectly smooth, with obtusely rounded corners, and a slight rounded projection in the centre of the concave edge; it is about 1.5 mm broad. The length of the radula is about 4.5, and its breadth above 1.5 mm; it is composed of about 105 tranverse, nearly straight rows of teeth, there being about 121 teeth in each row. The form of the teeth again very closely resembles that of Rot. anceps. All the points extend beyond the upper edge of the basal plate; the central is somewhat widened below the terminal point, contracted in the middle, but it has no distinct denticles at the sides. The laterals gradually become more and more turned, and curved, with a small inner and scarcely a trace of an outer denticle; up to the 20th they very gradually diminish in size, then a very slight break follows, the 21st being somewhat sensibly smaller and first distinctly bicuspid at the tip, while at the same time the size of the basal plate has much diminished, until in the last teeth it almost entirely becomes obsolete; the two terminal cusps on the other hand become gradually more and more equal.” (Stolizcka, 1873)
“The genital organs have a distinct amatorial gland, possessing near its origin a large globose appendage, internally composed of an elliptical largely cellular mass, in which the cells are concentrically arranged with their longer diameter perpendicular to the walls of the ellipse. The posterior part of the gland is filled with a finely granular substance, probably calcareous particles. The vas deferens has only one slight enlargement about the middle of its length; it consisted in a simple thickening of the walls, but I could not race any calcareous particles in it.; Towards the end, where the penis is lodged, the tube is widest and somewhat curved, but there are no other appendages, or calcareous sacs accompanied with a flagellum, present, such as have been observed in many other species of Rotula.” (Stolizcka, 1873)
Rotula bijuga – “ Dimensiones varietatum frequentium :- Diam. major 14.5-18.8, D. minor. 13.5-16.0, Alt. testae 10.9-12.0, Alt. aperturae 6.0-7.2, Lat. aperture 7.6-9.2 mm.” (Stolizcka, 1873); Macrochlamys pataniensis – “Dimensions; Largeur, 13 mm; hauteur du cône spiral au-dessus de la carène, 2 mm; hauteur totale, 7 mm; longueur de l'ouverture, 5.5 mm.” (Morgan, 1885)
Shell height – 14.5-17.4 mm; Shell width – 10.9-12 mm.
Type locality – Rotula bijuga “Penang” (Stolizcka, 1873); Macrochlamys pataniensis “le district de Rhaman, royaume de Patani.” (Morgan, 1885); Pseudoplecta bijuga convexospira “Kelantan? Or Malacca?” (Möllendorff, 1902)
Other localities – “Buket Pondong” leg. R. Hungerford & Townsend (Möllendorff, 1886); “Bukit Besar, Nawngchik, 3000 feet.” (Collinge, 1903); “Malay Peninsula; Langkawi Islands” (Laidlaw, 1933); “Malay Peninsula; Cameron Highlands” (Laidlaw, 1933)
“The species apparently occurs at all altitudes from sea-level to not less than 4500 ft.” (Laidlaw, 1933)