Opisthoporus rostellatus (Pfeiffer, 1851)
“If the remark of Stoliczka (Journ. As. Soc. Bengal, Vol. 41, 1872, p. 266) that the shells of male specimens of Opisthophorus penangensis reach the adult stage at a somewhat smaller size than the females, proves to be of wider application, it might perhaps inolve that Cyclotus rostellatus and C. dautzenbergi Sykes (Journ. Of Malac. Vol. 9, 1902, p. 23; Ibid. p. 61, pl. 3, fig. 5, 6) which seem to differ only in size, form the male and female phase of one species. Of the above mentioned series from Tinggi two shells are not quite ault. The other four measure resp. 14.8, 13.3, 12.5 and 11.9 mm. max. diam. peristome included. There is no possibility of separating the sexes as the animals are not preserved.” (Benthem-Jutting, 1949)
Pfeiffer (1851) original descriptions on Cyclostoma rostellatum – “T. umbilicata, depressa, solidula, cornea, strigis fulguratis castaneis ornate; spira brevisime turbinama, vertice mucronato, nigro; anfr. 4 ½ convexi, ultimus antice descendens, 5 mill. pone aperturam tubulo rostellatim circularis; perist. duplex, rubellum, internum continuum, subexpansum, adnatum, externum angulatim patens, superne breviter fornicato-dilatatum, infra anfractum penultimum angustissimum. Operc. testaceum, arctispirum, utrinque concaviusculum, intus rubrum, nitidum, margine sulcatum.”
Reeve (1864) descriptions on Pterocyclos rostellatus – “Shell moderately excavately umbilicated, subdiscoid, fulvous, wave-marbled with red-brown, whorls rounded, finely striated, last whorl with a small erect tube behind the aperture; aperture circular, lip expandedly reflected.”
Martens (1867) descriptions on Opisthophorus rostellatus – “Testa depressa, late umbihcata, leviter striatula, flavescens, strigis fuscis picta, apice nigricans; spira prominula, acutiuscula; anfr. 4½, teretes, sutura profunda discreti, ultimus sat descendens, 5-6 mill. ante aperturam tubulo suturali aperto recurvo mediocri munitus; apertura diagonalis, subcircularis, peristoma continuum duplex, externum breviter reflexum, rubellum, ad suturam in lobulum brevem rotundatum ascendentem, partim anfractui penultimo adnatum excurrens.”
Kobelt (1902) descriptions on Cyclotus (Opisthophorus) rostellatus – “Schale weit genabelt, niedergedrückt, leicht gestreift, gelblich mit braunen Striemen; Gewinde vorspringend, Apex schwärzlich, ziemlich spitz; Naht tief; 4 stielrunde Windungen, letzte ziemlich herabsteigend, 5-6 mm hinter dem Mundrande mit einer mittelstarken, zurückgebogenen Nahtröhre; Mündung diagonal, fast kreisrund; Mundraud zusammenhängend, doppelt, äusserer kurz zurückgeschlagen, rötlich, an der Naht in ein kurzes, abgerundetes, ansteigendes Läppchen vorgezogen, das sich zum Teil der vorletzten Windung anlegt.”
Cyclostoma rostellatum – “Diam. maj. 11, min. 9, alt. 5 mill. Apert. Intus 4 mill. diam.” (Pfeiffer, 1851); Opisthophorus rostellatus – “Diam. maj. 14, min. 10½, alt. 7; apert. long, et lat. 5½ Mill.” (Martens, 1867); Cyclotus (Opisthophorus) rostellatus – “H. 7, Durchm. 14:10.5 mm.” (Kobelt, 1902)
Type locality – “Sincapore” leg. Taylor (Pfeiffer, 1851)
Other localities – “Sumatra, im Flachland der Ostküste bei Mura dua am Musifluss von mir gefunden.” (Martens, 1867); “Borneo bei Sarawak” leg. Wallace (Martens, 1867); “Sumatra: Unter-Lankat” (Martens, 1900); “Tinggi Island” (Benthem-Jutting, 1949)