ANATOMY AND SYSTEMATICS OF CARDIOLUC1NA 



111 



Fig. 21 Cardiolucina semperiana (Issel, 1869). Figure a-b Paralectotype of Lucina pisum Reeve, 1850 BMNH 1963552, Singapore and c-d Holotype of 

 Dentilucina (Bellucina) macassari Prashad, 1932, Makassar, Indonesia, ZMA. a, exterior of right valve; b, interior of left valve; c, exterior of right valve; 

 d, interior of left valve with attempted drill hole on the posterior part of the umbo. Scale bars a-d = 1 .0mm. 



which the anterior is the smaller. Right valve with single posterior 

 and anterior laterals and two cardinals, the posterior being the larger. 

 Cardinal teeth have small denticles. Ligament extends two thirds of 

 the distance from the beak to the posterior lateral tooth. Inner margin 

 with 20-21 crenulations and there are also small, rounded denticles 

 along anterodorsal and posterodorsal margins. Both anterior and 

 posterior shell margins have shallow sinuses corresponding to the 

 sulcii. Anterior adductor muscle scar elongate, buttressed in the 

 more tumid specimens, detached from the pallial line only at the 

 ventral tip. Small pedal retractor muscle scar at dorsal tip of anterior 

 adductor scar. Posterior adductor muscle scar ovate. Pallial line 

 continuous. Shell creamy white. 



ANATOMY. (Fig. 22 ) Posterior inhalant aperture absent, exhalant 

 aperture a small inverted tube. Ctenidia large and thick, inner 

 demibranchs only, with a thin, shallow, ventral food groove. Gill 

 filaments long and broad, with large central space crossed by 

 transverse muscle strands (Fig. 22 c). Bacteriocyte zone packed with 

 ovoid bacteria about 2.0-2.5 urn in length (Fig. 22 d). Labial palps 

 consist of small papilla at edge of lips. Foot cylindrical, vermiform, 



with a much-corrugated outer surface, a pointed tip and a small 

 rounded heel to the posterior. Ctenidia attached to posterior mantle 

 by a thin muscular sheet (Fig. 22 0- Body wall with a large irregular 

 visceral pouch in the antero-ventral position. 

 Geographical variation. This species is extremely variable 

 both within populations and across its range from the northern end of 

 the Red Sea to the Philippines. In Southeast Asia semperiana are 

 generally smaller, but relatively more tumid, as shown in Fig. 23, 

 which plots ratio of length over tumidity against mean height of 

 specimens from Red Sea, Madagascar, India, South East Asia. The 

 holotype of macassari is the most tumid of all the specimens 

 measured, but is probably an abnormal individual which has sur- 

 vived attempted drilling at the posterior dorsal margin. C. semperiana 

 from Southeast Asia also tend to have fewer, but heavier, concentric 

 lamellae (Figs. 21). 



Habitat. Live material collected from shallow water (up to 50 m), 

 a few dead shells from up to 350 m, mud and sand. 

 Comparison with other species. C. semperiana is similar to C. 

 rugosa but is larger, more tumid and has more prominent radial ribs. 



