Cyclotus trusanensis Godwin Austen, 1889
“A single dead shell compares well with Museum specimens. It is 21.7 mm in diameter, 7.3 mm high with 4 ¾ whorls. The flat spire with not even the apex protruding, lack of a breathing tube and close appression of the body whorl to the penultimate easily separates trusanensis from C. iris. Five species of typical Cyclotus have been described from Borneo.” (Solem, 1964)
Godwin-Austen (1889) original descriptions on Cyclotus trusanensis – “Shell discoid, very widely umbilicated; all the whorls showing; sculpture a thick epidermis, with lines of growth; colour dark amber brown, with a few small splashing of ochre; spire flatly depressed; apex scarcely rising above the last whorl; suture impressed; whorls 5, rounded, the last slightly descending; aperture circular, oblique; peristome double, inner simple, continuous, the outer slightly reflected, gradually expanding towards the margin, forming at the suture a small wing, which is attached to the penultimate whorl. Operculum shelly in front, flatly concave, with a small central circular depression, horny at back, surface flat.”
Kobelt (1902) descriptions on Cyclotus (Cyclotus) trusenensis – “Schale sehr weit genabelt, scheibenförmig, gestreift, tiefbraun mit zerstreuten gelben Flecken; Periostracum dick; Gewinde flach, Apex kaum vorspringend; 5 abgerundete Windungen, letzte langsam herabsteigend; Mündung schräg, kreisrund; Mundrand doppelt: innerer einfach, zusammenhängend, äusserer leicht zurückgeschlagen, vorn allmählich ausgebreitet, oben mit angewachsenen Öhrchen.”
Cyclotus trusanensis – “Size (of shell drawn): maj. diam. 18.5, min. 15.0; alt. axis 4.5; diam. aperture 7.80 millim. Size(largest in collection): maj. diam. 22.5, min. 17.5; alt. axis 5.0; diam. aperture 9.0 millim.” (Godwin-Austen, 1889); Cyclotus (Cyclotus) trusenensis – “H. 4.5-5, Durchm. 18.5-22.5 : 15-17.5 mm.” (Kobelt, 1902)
Type locality – “Trusan island” leg. A. Everett (Godwin-Austen, 1889)
Other localities – “Lower Kinabatangan District” (Solem, 1964)