Trogloconcha ohashii is a species of minute sea snail, a marine gastropod mollusc in the family Larocheidae (formerly classified within Scissurellidae). It was first described in 2002 by malacologists Tomoki Kase and Yasunori Kano.
Taxonomy and Etymology
The genus name Trogloconcha is derived from the Greek words trōglē (cave) and konchē (shell), referring to its habitat in submarine caves. The species epithet ohashii honors Shu-ichi Ohashi, a professional SCUBA diver from Naha, Okinawa, Japan, who assisted in collecting specimens. The species was described in the journal The Veliger in 2002.
Description
Trogloconcha ohashii possesses a minute, thin, fragile shell that is depressed-turbiniform in shape, typically measuring 0.87–1.34 mm in diameter and 0.64–0.94 mm in height. The shell is opaque white, umbilicate, and lacks an anal slit, notch, or selenizone. The teleoconch surface features a reticulate (net-like) pattern formed by intersecting axial riblets and spiral cords that produce tiny tubercles. The protoconch (larval shell) is globular and smooth, measuring 142–176 μm in diameter. The aperture is large and subovate, and the operculum is rudimentary, multispiral, thin, and corneous.
The radula is rhipidoglossate, with a formula of approximately ∞-5-1-5-∞ and about 85 transverse rows of teeth. The species is gonochoristic (separate sexes) with no sexual dimorphism or brooding behavior.
Distribution and Habitat
Trogloconcha ohashii is distributed across the tropical to subtropical Indo-Pacific region, from the Cocos (Keeling) Islands and Christmas Island in the eastern Indian Ocean to French Polynesia in the central Pacific, including Indonesia, the Philippines, Japan (Ryukyu Islands), Palau, Micronesia, and Melanesia. It is exclusively found in submarine cave environments at depths ranging from 4 to 51 meters, inhabiting dark to totally dark conditions on calcareous muddy sand substrates, often attached to the undersurfaces of coral rubble.
Biology
The species is detritivorous, feeding on fine organic detritus and associated microorganisms. It exhibits several adaptations to cave life, including an opaque white shell (loss of pigmentation), reduced eyes (closed structures on short stalks), and enhanced chemosensory capabilities through long cephalic tentacles with micropapillae. Live specimens are rarely encountered despite the abundance of empty shells in cave sediments, suggesting low population densities.
References
- Kase T. & Kano Y. 2002. Trogloconcha, a new genus of larocheine Scissurellidae (Gastropoda: Vetigastropoda) from tropical Indo-Pacific submarine caves. The Veliger 45(1): 25–32.
- Bouchet, P.; Fontaine, B. (2009). List of new marine species described between 2002-2006. Census of Marine Life.
- Geiger, D.L. (2012). Monograph of the little slit shells (Gastropoda: Scissurellidae). Bishop Museum Bulletin in Zoology.
