Shell moderately thin but strong, trigonal, smooth to glossy, well inflated, becoming somewhat attenuate posteriorly in large adults; umbones prosogyrate (markedly so in large adults) and raised; lunule elongate heart-shaped to lanceolate, flat, weakly delineated by incised line; anterodorsal margin short, steeply sloping; narrowly convex terminally; ventral margin convex (slightly sinuate in very large adults); posterodorsal margin straight, steeply sloping, narrowly rounded at its extremity. Sculpture of fine, dense, growth striae supplemented by raised concentric ridges ventrally, anteriorly and posteriorly. Colour externally white, with black, chestnut or dark-brown chevron or hieroglyphic patterns and microscopic dots; umbones and lunule white, with purple spots beneath umbones; shell internally white, yellow centrally. Periostracum straw coloured. Shell length to 41 mm.

Distribution and habitat
Western Pacific and Eastern Indian Ocean (Irian Jaya), in coral sand, lagoonal and reef areas. Holotype. Australia: Queensland: Swain Reef, dredged coral sand, D. and V Harris, 1986, QM M0.22852 (lpv).
Paratypes. Australia: Queensland: Lady Musgravc Island, coral sand, 3-7 m, dredged, D. and V. Harris, 1986, AMS C.160474 (lpv), WAM.941-89 (lpv).
Other material examined. Australia: Queensland: Lady Musgravc Island, in lagoon, AMNH.303126 (4pv); Herald Prong Reef, Swains Reef, AMNH.303163 (6pv); Kelso Reef, dredged 3-7 m coral sand, MV F57681 (lpv); Taylor Reef; KL (lpv), AMNH.303029; Kelso Reef, AMNH.303025 (lpv); Swains Reef, AMS C.132082; Queens Beach, Bowcn, AMS C.75887 (in part); Rudder Reef, off Port Douglas, AMS C.138072 (4pv); Murray Island, Torres Strait, AMS C.138080. New Caledonia: Poum Bay, Daomboui Island, 0-3 m, in sand and coral, 20°9'S, 163°59'E, AMS C.356679 (in part) (lpv) (preserved); Anse Vata, Noumea, AMNH.303031-AMNH.303269 (2pv); Baic des Citrous, Noumea, AMNH.303034 (lpv); Crouy Reef, Noumea, AMNH.303030 (lpv). (For further New Caledonian sites, refer to Lamprell and Stanisic (1996).) Indonesia: Wai Island, Sorong, NW Irian Jaya, 5-10 m in rubble on coral slope, AMNH.303045 (lpv). Philippine Islands: Bohol Island, Tagbilaran, 9°39.000'N, 123°51.000'E, AMS C.371090 (llv).

Lamprell and Whitehead (1990) differentiated L. annettae from L. tigrina and L. fastigiata on the basis of valve profile, sculpture and colouration. They further separated L. annettae from L. fastigiata using habitat preferences (reef for the former, mainland coastal for the latter), maximum shell length and the length of the teeth. Examination of a more extensive series of specimens (including juveniles) than that available to Lamprell and Whitehead suggests that there are no significant differences between the species as regards teeth length or valve profile. Whereas it is true that mature L. fastigiata tend to be smaller (generally 25-30 mm in length) than L. annettae (generally 30-40 mm in length), we have examined a number of specimens of L. fastigiata comparable in size to average L. annettae. The differences between L. annettae and L. fastigiata in habitat preference, adult sculpture and colouration (including lunule colouration) appear to hold, but the basic patterning of the shells is similar and suggestive of a close relationship. As to the precise nature of this connection, whether that of sister species, subspecies or populational variants, nothing can as yet be concluded. Lamprell and Stanisic (1996) recorded L. annettae from several subtidal stations off New Caledonia. We can confirm this, but add that several interesting specimens from this region appear to be intermediate between L. annettae and L. ornata,
suggestive of occasional hybridisation and, as with L. fastigiata, also a close relationship. Lamprell and Stanisic (1996) previously indicated that L. annettae and L. ornata may eventually prove to be conspecific but, based on shell features alone, the closest relationship of L. annettae would seem to lie with L. fastigiata.