Geotrochus rhysa Tillier & Bouchet, 1988
Tiller & Bouchet (1988) original descriptions on Trochomorpha rhysa – “Shell medium-sized, solid, depressed, lenticular, consisting of 2 protoconch and 3.5 teleoconch whorls. Protoconch sculptured by numerous strong and regular incremental wrinkles starting in the nuclear region. No spiral sculpture on the protoconch. Protoconch/teleoconch transition very distinctly demarked by the appearance of spiral sculpture on the teleoconch. Teleoconch whorl rather convex for the genus, with a deep suture; body whorl occupying 71% of total shell height,with a strong sharp peripheral keel. Spiral sculpture of raised spiral threads, not extending onto the base of the shell; this is the only sculpture present on the earlier teleoconch whorls, later also irregular axial costules appear, intersecting with the spiral threads to produce a shagreened sculpture on the body whorl. Basal part of the shell smooh, only with low axial (radiating) costulae. Aperture rhomboid, the outer lip forming a sharp angle at the level of the peripheral keel. Thin inner lip glaze coating the body whorl. No umbilicus. Colour of the shell plus periostracum brown with lighter (yellowish-brown) apex and periphery; columellar pillar white.”
“The radula has more than 100 teeth per row. The central an ca. 15 lateral teeth (per half row) are almost unicuspid, with only traces of ecto- and endocone. The marginal are bicuspid, the ectocone being distinctly shorter than the mesocone.” (Tiller & Bouchet, 1988)
“The foot is aulacopod, the tail being truncated and exhibiting a caudal foss. The visceral mass is 5.3 whorls long in the dissected paratype, entirely mottled with black externally. The pallial complex is 0.6 whorls long. It is fully sigmurethrous and exhibits a long, narrow kidney which occupies ca. 0.42 of lung length. The oesophagus is internally lined with thin longitudinal ridges. The stomach occupies 1.4 whorls above the lung; the stomachal crop increases in diameter towards the stomachal puch which is well-developed. There is an internal ridge joining the openings of the digestive gland, but no apparent typhlosole. The intestinal loops occupy ca. 0.25 whorls just above kidney top. The upper lobe of the digestive gland and hermaphrodite gland occupy the upper 3.3 whorls proximally to the stomach.” (Tiller & Bouchet, 1988)
“Central nervous systems: its characters are quite similar to those of Trochomorpha as depicted by Baker (1941, Pl. 51, Fig. 14): short cerebral commissure and cerebral ganglia obliquely elongated; cerebro-pedal and cerebro-pleural connectives short; ganglia of the visceral chain all distinct, the left parietal being separated from the left pleural by a distinct connective, whereas the other ganglia is the visceral chain appear appressed together.” (Tiller & Bouchet, 1988)
“Genital apparatus: the hermaphrodite gland is formed of four distinct lobes, one of them being subdivided into two masses, in the dissected paratype. The median portion of the hermaphrodite duct is contorted, whereas its proximal and distal portions are nearly straight. There is a talon, which appears to be formed from two pouched appressed together. In the distal part of the hermaphrodite and female tracts, the vagina is shorter than the free oviduct, of which the proximal half is occupied by a glandular zone. The spermatheca is short, being hardly longer than the free oviduct, its cylindrical head being slightly longer than its stalk. The atrium is long. The penis is more than twice as long as the vagina and free oviduct; no sheath is visible. No epiphallus may be distinguished externally. The penial retractor is inserted apically, and vas deferens enters laterally into the penis apical region. Internally the penis exhibit thin chevron-shaped ridges, and a single thin pilaster occupies its median region.” (Tiller & Bouchet, 1988)
Trochomorpha rhysa – “Dimensions of the shell (holotype): height 5.8 mm, diameter 9.2 mm; aperture height 3.2 mm, breadth 4.8 mm.” (Tiller & Bouchet, 1988)
Type locality – “upper montane zone of Mt. Kinabalu (Sabah, Borneo)” (Tiller & Bouchet, 1988)