Cremnoconchus agumbensis Reid & Aravind & Madhyastha 2013, SP. NOV.
Creators: name: Reid, David G.
name: Aravind, Neelavara Ananthram
name: Madhyastha, Neelavara Ananthram
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Littorinimorpha
Littorinidae
Cremnoconchus
Cremnoconchus agumbensis

description: CREMNOCONCHUS AGUMBENSIS SP. NOV.  (FIGS 4H, 5M, N, 8, 11M–P, 13C, D, 14A–C, 16E)  
 Types: Holotype ZSI / WGRS /IR.INV-2313 (Fig. 11M, N); 2 paratypes ZSI / WGRS /IR.INV-2314, 2315 (Fig. 11O, P); Someshwara to Agumbe road, Udupi Dist., Karnataka, India (13.49342°N, 75.07783°E).   
 Etymology: From the type locality.   
 Diagnosis: Shell high turbinate, shoulder angled or with rib; pseudumbilicus absent; surface dull, with strong microstriae. Operculum calcified, no internal ridge. Penis large, with distal glandular thickening, stout filament. Western Karnataka State.   
 Shell (Figs 4H, 11M–P): Shell H 5.5–10.4 mm. Shape (Table 1) high turbinate; whorls strongly angled at shoulder (sometimes raised as a rib; Fig. 11N), giving pronounced sutural ramp or channel, but becoming weak at end of last whorl; slight angle at periphery; suture impressed; apex slightly eroded; base slightly swollen. Columella narrow. Pseudumbilicus absent. Surface with single narrow rib at shoulder; dull, with irregular but distinct microstriae, fainter on last whorl and on base (Fig. 4H). Protoconch (Fig. 16E) 1.5 whorls; diameter 0.68 mm; diameter of first whorl 0.53 mm (n = 1). Colour: dark brown, darker on spire, three more or less distinct broad black-brown bands at shoulder, above periphery and on inner part of base; aperture pale brown, columella and interior bands purple-brown.   
 Animal: Head, tentacles and sides of foot black, paler at tip of snout. Gills: up to 50 leaflets; unpigmented. Operculum (Table 1; Fig. 5M, N): opercular ratio 0.439 –0.565; calcified, no internal ridge. Penis (Fig. 14A, B): relatively large; unpigmented; base wrinkled, strap-shaped, with slightly thickened distal glandular region; filament relatively stout, protruding in ethanol-fixed specimens. Pallial oviduct (Fig. 14C): as for genus. One pallial oviduct contained two eggs 0.40 mm diameter (ethanol fixed).   
 Radula (Fig. 13C, D): Relative radula length 1.09– 1.79. Rachidian: length/width 1.19–1.42; 5 cusps (+ 1 outer denticle on either side). Lateral: 6 cusps (sometimes + 1 inner denticle). Inner marginal: 5 cusps (sometimes + 1 inner denticle). Outer marginal: 4 cusps (sometimes + 1 inner denticle). Major cusp of each of 5 central teeth elongate-triangular with rounded and slightly papillose tip; other cusps pointed.   
 Range (Fig. 8): Western Karnataka State, Agumbe (75 km north-northeast of Mangalore). Records (Supporting Table S1): Karnataka State: Someshwara to Agumbe road (ZSI / WGRS /IR.INV-2313, 2314, 2315).   
 Habitat and ecology: Damp rock face shaded by evergreen forest. Altitude 379 m.   
 Remarks: Among the known Cremnoconchus species of Karnataka, C. agumbensis is the only one with turreted whorls produced by a sharp angulation (or rib) at the shoulder, and without a pseudumbilicus (Table 4). In these characters it resembles the canaliculate form of C. canaliculatus from Maharashtra (Table 3; Fig. 9P, R, U–Z, CC), but that has a more solid shell and the penis bears a drum-shaped gland (Fig. 10I–N).
description: Published as part of Reid, David G., Aravind, Neelavara Ananthram & Madhyastha, Neelavara Ananthram, 2013, A unique radiation of marine littorinid snails in the freshwater streams of the Western Ghats of India: the genus Cremnoconchus W. T. Blanford, 1869 (Gastropoda: Littorinidae), pp. 93-135 in Zoological Journal of the Linnean Society 167 (1) on pages 121-124, DOI: 10.1111/j.1096-3642.2012.00875.x, http://zenodo.org/record/5292273