Shell very thin, ovate, smooth but not glossy; lunule lanceolate, raised, well delineated by incised line; sculpture of crowded, flattened concentric ridges tending to anastomose at margins; rib interstices narrow, shallow. Colour externally tan with a network of white solid triangular markings; umbones pink, lunule white; shell internally white with external colour patterns visible through shell surface; dorsal margin with external pattern crossing both valves. Shell length to 11.25 mm.

Distribution and habitat: New Caledonia and Queensland, in sand to 110 m. Holotype. New Caledonia: Secteur de Pouebo, Lagon (lpv) stn 876, 30-70 m, 20°35'S, 164°51'E, 30-70 m, 13 Jan 1987, MNHN. Paratypes. New Caledonia: Secteur de Poindimic Lagon (91v, 8rv many juveniles), stn 830, 105-110 m, 20°49'S, 165°19'E, 10 Jan 1987, MNHN; Secteur de Pouebo, Lagon: stn 876, 30-70 m, 20°35'S, 164°51'E, 13 Jan 1987, AMS C.305575 (2pv, 1 rv, llv).
Other material examined. Australia: Queensland: Lindeman Island, AMS C.358028 (2rv); off Cairns, 192 m, AMS C.358030 (llv); Michaelmas Cay 20 m, AMS C.358024 (5 rv, 21v); St Crispins Reef, AMS C.46277(6rv, llv). New Caledonia: Plateau Chcstcrfield-Bcllona, Chalcal l,stnD21 MNHN(llv); Grand Recif Sud, Lagon, stn 324 MNHN (lrv); Secteur des Belep, Lagon, stn 1104 MNHN (lrv).

This is the smallest known species of Lioconcha and its combination of greatly reduced size, heavy triangle patterning, ovate valves and poorly projecting umbones easily separates it from other heavily ridged members of the genus. Lioconcha gordoni is also small, but can be distinguished from L. richerdeforgesi by having much coarser ridges, a zigzag pattern and a glossy surface. Of the other small, ridged species of Lioconcha, L. caledonensis is larger, less patterned and exhibits a longer lunule than L. richerdeforgesi, whereas L. melharteae has thin, very inflated valves and a distinctive colour pattern featuring a single large ray of orange and an orange dorsal margin. Lioconcha philippinarum varies little in valve shape or colour from juvenile to adult and is unlikely to be confused with L. richerdeforgesi.