Cyclotus tener (Menke, 1856)
”Coquille largement ombiliquée, subdiscoïde, assez solide, finement striée et d'un fauve olivâtre; spire peu élevée; 5 tours de spire convexes; dernier tour renflé près de la suture et légèrement sillonné, détaché en avant et muni, au-dessus de l'incision du péristome, d'un tube court et légèrement incurvé; ouverture libre, presque verticale, circulaire; péristome légèrement épaissi et à faible expansion.” (Pfeiffer, 1862)
“Compared with specimens of this species (Opisthophorus tener, Menke) from Annam (coll. Fruhstorfer), I can trace but little distinction except size, one of the adult Kelantan shells, for example, only measuring diam. max. 13.5 millim. The tube is also slightly more parallel to the suture.” (Sykes, 1902)
“The two specimens sent agree fairly with the figures published (Journ. de Conch., x, 1862, p. 45, pi. vi, fig. 5; Couch. Icon., No. 23), but are smaller in dimensions (diam. maj. 14, min. 11 mm.; alt. 6 mm,). This species and P. (Rh.) tener are intermediate in character between typical Rhiostoma, with the last whorl free for some distance near the aperture, and the forms of Pterocyclus inhabiting the countries to the east of the Bay of Bengal. P. marioni, Ancey (Bull. Mus. Marseille, i, 1898, p. 137, pi. ix, fig. F), is a typical Rhiostoma, near P. housei, with which it has been united by Dautzenberg.” (Blanford, 1903)
Menke (1856) original descriptions on Pterocyclos tener – “T. umbilicata, depressa, tenera, costis prominentibus membranaceis munita, pellucida, virenti-cornea; spira medio vix elevata; anfr. 5 convexiusculi, ultimus teres, antice solutus; umbilicus latus, 2/5 diametri subaequans; aperture parum obliqua, subcircularis, intus leviter margaritacea; perist. subduplex: internum superne breviter incisum, praeterea subadnatum, externum brevissime patens, incisuram prominentia levi tubuliformi obtegens. Operc?”
Pfeiffer (1862) original descriptions on Rhiostoma bernardii – “T. late umbilicata, subdiscoidea, solidula, capillaceo-striata, sericea, olivaceo-fulva; spira parum élevata, vertice minuto, prominulo; anfr. 5 convexî, ultimus teres, juxta suturam tumidus et leviler sulcatus, antice solutus et supra incisuram peristomatis tubulo brevi curvatulo munitus; apertura libera, fere verticalis, circularis; perist. subincrassatum, breviter expansum.”
Reeve (1864) descriptions on Pterocyclos tener – “Shell largely umbilicated, subdiscoid, transparent yellow, whorls rounded, finely ring-striated throughout; aperture circidar, lip thin, duplicate, sin\is produced into a small recurved tube.”
Reeve (1864) descriptions on Pterocyclos bernardii – “Shell largely umbilicated, somewhat discoid, fulvous, whorls rounded, finely ring-striated; aperture circular, lip thickly reflected, sinus produced into a small incurved tube. Of simple form and semitransparent fulvous colour, with a small incurved tubular sinus.”
Kobelt (1902) descriptions on Rhiostoma bernardii – “Schale weit genabelt, fast scheibenförmig, ziemlich festwandig, fein haarstreifig, seidenglänzend, olivenbraun; 5 gewölbte Windungen, letzte stielrund, an der Naht aufgetrieben, leicht gefurcht, vorn abgelöst, über dem Einschnitt mit kurzer, gebogener Röhre; Mündung frei, fast senkrecht, kreisrund; Mundrand leicht verdickt, kurz ausgebreitet.”
Pterocyclos tener – “Diam. maj. 17, min. 13, alt. 6 mill. Apert. diam. 5 2/3 mill.” (Menke, 1856); Rhiostoma bernardii – “Diam. maj. 15, min. 12, alt. 7 mill.” (Pfeiffer, 1862); Rhiostoma bernardii – “H. 7, Durchm. 15 : 12 mm.” (Kobelt, 1902)
Type locality – Pterocyclos tener “Touranne Cochinchinae” (Menke, 1856); Rhiostoma bernardii “Siam” (Pfeiffer, 1862); Cyclotus (Siphonocyclus) solutus subsolutus “Kelantan” (Moellendorff, 1902)
Other localities – Opisthophorus tener “Kelantan, Malay Peninsula” leg. J. Waterstradt (Sykes, 1902); “Malay Peninsula; Tale Sap” (Laidlaw, 1928)
Habitat – “Found on rocks only." (Blanford, 1903)