Opisthoporus iris (Godwin Austen, 1889)
“The 12 Bornean Opisthophorus seem to be extremely closely related. They differ in the degree of freedom of the last whorl, length and direction of the breathing tube, size and lip form. Identification of the above specimens with iris is based on Museum material an Godwin-Austen’s illustration, since Kobelt’s rather poor figure may not represent that species. The Gomantong Hill example is 16.5 mm in diameter, one Bukit Kipangi shell is 15.5 mm and the other range from 17.2-20.3 mm. The single Dewhurst Bay adult is 20.5 mm in diameter. Collections of living examples are needed, however, before any judgement as to geographic as opposed to possible seasonal variation can be undertaken.” (Solem, 1964)
Godwin-Austen (1889) original descriptions on Rhiostoma iris – “Shell depressedly turbinate, openly and perspectively umbilicated; colour deep ochre, with regular zigzag bands of ruddy brown crossing the whorls; spire just raised above the last whorl; apex blunt; suture well impressed; whorls 4, rounded, the last separated from the penultimate for about 5 mm from the aperture, where the sutural tube rises, this is short, horizontal, and directed forwards; aperture oblique; peristome double, continuous, inner simple, outer expanded at right angles to the body-whorl, more particularly on the outer margin, and increasing to a crinkled expansion or wing on the upper margin and directly in front of the sutural tube, this wing terminates abruptly on the columellar side. Operculum with a smooth central spot, multispiral, shelly, flatly concave.”
Kobelt (1902) descriptions on Cyclotus (Opisthophorus) iris – “Schale weit und durchgeheud genabelt, niedrig kreiseiförmig, ockerfarben, mit regelmässigen, rotbraunen Zickzackstriemen; Gewinde kaum erhoben, Apex etwas stumpf; Naht eingedrückt; letzte Windung von dem 5 mm hinter dem Mundrande liegenden, kurzen, nach vorn gerichteten Röhrchen an abgelöst; Mündung schräg; Mundrand zusammenhängend, doppelt: innerer einfach, äusserer zurückgeschlagen, oben geöhrt. Öhrchen links plötzlich abgestutzt. Deckel flach ausgehöhlt, mit vielen Windungen und glattem Nucleus.”
Rhiostoma iris – “Size: maj. diam. 18-25, min. 14.0; alt. axis 5.75 millim.” (Godwin-Austen, 1889); Cyclotus (Opisthophorus) iris – “H. 5.75, Durchm. 18.25:14 mm.” (Kobelt, 1902)
Type locality – “Borneo” coll. Hungerford (Godwin-Austen, 1889)
Other localities – “Kinabatangan District, East Coast Resideney, North Borneo, from the southeast end of Dewgurst Bay.” Leg. D. D. Davis & R. F. Inger/May 1950 (Haas, 1951); “Sabah; Bukit Kipangi” (Solem, 1964); “Sabah; Gomantong” (Solem, 1964); “Sabah; Dewhurst Bay” (Solem, 1964)