Bairdoppilata

Bairdoppilata sp. 5

(Figs. 3.11a, 4, 16)

1974 in part Bairdoppilata sp. 44, Hartmann: 253.

Material. 1 dissected A F, fragmented soft parts on a glass slide containing permanent medium “Hydromatrix” plus both valves on micropaleontological slide (K­ 30230b); 1 LV, 2RV, Knysna Beach, South Africa, ZMH K­ 30230. These specimens were studied but not illustrated by Hartmann (1989).

Distribution. Knysna Beach, South Africa, Southeastern Atlantic.

Measurements. A LV, L 1.08mm, H 0.70mm (K­30230b); A RV, L 1.06mm, H 0.62mm (K­30230b); (A­ 1) LV, L 0.91mm, H 0.54mm; (A­1) LV L 0.86mm, H 0.44mm; (A­2) RV, L 0.76mm, H 0.38mm.

Description. LV globose­subtriangular in lateral view, anterior conspicuously more broadly rounded than posterior, not caudate, dorsal margin highly arcuate, posterior margin upswung. RV subhexagonal in lateral view, anterior and posterior similarly broad, posterior upswung, slightly caudate, dorsal margin tri­segmented, posterior segment slightly concave and shorter than anterior segment, ventral margin sinuous. Valve surface of adults smooth. Normal pore canals large, numerous, with conspicuous rim, sensilla very numerous, and of variable length (from small to long). Barbed fringe, but no denticles, present anteriorly and posteriorly on RV. No fringe or denticles present on LV. Calcified inner lamella medium­sized, vestibules constricted. Hinge anterior and posterior elements with 5 well developed denticles and sockets. Nine adductor muscle scars present, eight of them positioned in a circle surrounding the ninth scar.

Podomere VI of AII with 3 robust terminal claws, fused claw shorter than other 2 claws, exopodite with 2 tiny setae and 1 long seta. Md with 5 trifurcate teeth. MxI with several feathered, broad claws, palp with 3 dorsal, 1 ventral, and 1 distal setae, and 1 broad, robust, feathered distal claw. Fu with (from distal to proximal) one medium sized and 1 long claws, plus 6 medium­sized setae. Genital lobe globose, with short, coiled, internal tube.

Remarks. The specimens herein identified as Bairdoppilata sp. 5 were identified by Hartmann (1974) as Bairdoppilata sp. 44, and assigned to B. simplex by Dingle (2003). Bairdoppilata sp. 5 presents: (1) more globose carapace; (2) more conspicuous hinge denticulation; (3) anterior and posterior, barbed fringes on RV; (4) and more numerous sensilla than B. simplex (Fig. 16).

Hartmann (1974) described a very strong sexual dimorphism for his Bairdoppilata sp. 44, but actually he was dealing with at least 2 different species (Bairdoppilata sp. 5 and B. sp. 6 herein).