Shell robust, relatively large for the genus. Protoconch: with about 1 whorl; transition to the teleoconch obscure; one broad, shallow groove on the outer side; initial part of the groove with relatively strong, irregularly spaced lamellae; lamellae obscure on the remaining portion of the groove; about four axial ribs, ending at the inside of the groove and becoming strongly nodulous here. Teleoconch: about 1,5 whorls; first half whorl with one spiral row of strong nodules on the exterior part, crossed by about six very fine spiral threads, the latter being absent on the inner part of the whorl; last whorl of the teleoconch with a double spiral row of strong and broad nodules, the exterior ones being stronger than the inner ones; two rows separated by one broad, shallow groove; the interspaces between the nodules with very fine spiral threads, the latter becoming more obsolete on the nodules; number of nodules varying from 13-17 (16 in the holotype); periphery with one strong carina, becoming stronger on the last part of the whorl; interspace between the nodules and the carina with weak, irregularly spaced, axial ribs; suture obvious, deeply impressed. Aperture: subquadrate; peristome continuous; inner lip completely attached to the previous whorl. Colour: semitransparent, dark brown. Shell-dimensions (in mm): 0.56-0.65 mm. (diameter).

Ammonicera binodosa sp. nov. superficially resembles A. nodicarinata Sleurs, 1984, from Papua New Guinea; the latter, however, has only one row of nodules on the ventral and dorsal sides of the shell, and the spiral groove on the protoconch is narrower than in A. binodosa sp. nov. The operculum of A. nodicarinata lacks the apophysis of A. binodosa sp. nov.
A. binodosa sp. nov. has the same overall features as observed in the other Ammonicera species, i.e. the presence of a spiral groove on the protoconch, the ornamentation of the teleoconch and the typical radular features, the latter showing no differences with any other species so far studied. The operculum, however, differs from all other species so far studied, by the presence of a strong central apophysis; therefore this new species binodosa is only tentatively placed in Ammonicera Vayssiere, 1893.

Type-locality. — Republic of Maldives, North Male Atoll, Baros Island