98 



J.D. TAYLOR AND E.A. GLOVER 



Fig. 3 Cardiolucina australopilula new species, a, Holotype, hinge in the right valve; b. Holotype, hinge in the left valve; c, Paratype, left valve, detail 

 of cardinal teeth; d, outer shell surface showing radial striations on radial ribs. Scale bars a=2.0mm, b=2.5mm, c=1.0mm, d=500um. 



aperture. The exhalant aperture consists of a muscular tube with a 

 flared distal end, which is inverted in preserved specimens, but can 

 presumably be protracted. The ctenidia comprise inner demibranchs 

 only. These have large, thick filaments which are fused between the 

 ascending and descending lamellae. To the posterior, the outer 

 lamellae are attached to the mantle margin just ventral to the 

 exhalant aperture. The attachment area forms a thin, muscular 

 septum. The labial palps consist of small folds at the edge of the thin, 

 ridge-like lips. The foot is cylindrical and vermiform, tapering to a 

 blunt point and extending posteriorly with a rounded heel. The 

 visceral mass is covered by a muscular wall with a single, large, 

 hemispherical visceral lobe on each side. The rectum runs around 

 the dorsal side of the posterior adductor muscle and opens into the 

 mantle cavity close to the exhalant tube. 



Comparison with other species. This species is similar in size, 

 shape and sculpture to C. quadrata (Prashad, 1932) (Fig. 16) but 

 differs in the greater prominence of the radial ribs and thinner, 

 concentric lamellae. C. australopilula is also more tumid and spheri- 

 cal. This species has been referred to as Bellucina cf. semperiana by 

 Slack-Smith (1990), but semperiana is smaller, with different orna- 

 mentation and hinge teeth. 



Habitat. Fine, well-sorted, calcareous sand between 30-40m, in 

 association with other bivalves Amusium balloti, Mimachlamys 

 australis and Rastafaria thiophila (Glover & Taylor 1997). 



Distribution. Western Australia, Houtman Abrolhos Islands to 

 Broome (Fig. 6). 



Etymology, australopilula meaning 'Australian little ball'. 



MATERIAL EXAMINED. WESTERN AUSTRALIA: Broome (AM 

 C. 309449); Roebuck Bay, Broome (BMNH 1892.1.29.121); 

 Montebello Islands, Bunsen Channel, N. end of Trimoville I. 20° 

 23.8'S; 1 15° 32.43'E 3m (WAM); Barrow Island 20° 53'S, 1 15° 20'E 

 (WAM); Exmouth Gulf (WAM 3461-3468); Mauds Landing, N.W 

 Cape, 3m (WAM); Turtle Beach, off N.W Cape (AM C.309456); 

 Carnarvon (AM C.309455); Dirk Hartog Island, 10-20m (WAM 

 3475.68); Bernier Islands 24° 53.3'S 113° 17.5'E. (WAM); Shark 

 Bay, Peron Peninsula (WAM 249.94); Shark Bay, 5 km E.S.E. Cape 

 Heirisson, 18m (WAM); Shark Bay, Freycinet Estuary (WAM 252- 

 94). Houtman Abrolhos Islands: N. of Wallabi Islands, 40m (BMNH 

 ace 2384); Easter Group, 50m (WAM N-2777); Zeewyk Channel, 

 40m (WAM N-2822); Little North Island, Easter Group, 40m 

 (WAM); Rat Island, 30m (WAM wet material); East of Good Friday 

 Bay, 28° 39.5'S - 1 13° 49.5E, 40m (WAM). 



