Bairdoppilata cratericola Maddocks, 1969

Maddocks, Rosalie F., 2022, Taxonomic applications of the esophageal flapper valve in Bairdoppilata and Glyptobairdia (Bairdiidae, Ostracoda), with comments on anatomy, ontogeny, and geography, Zootaxa 5175 (3), pp. 301-342 : 312-313

Bairdoppilata cratericola Maddocks, 1969

( Figures 1L–Q , 2F–H )

1969 Bairdoppilata (Bairdoppilata) cratericola Maddocks : 75, fig. 39A–H.

1995 Bairdoppilata cratericola Maddocks. —Maddocks, p. 216, pl. 6, figs. 3–8; pl. 14, figs. 3–6.

Material Examined: One adult living female, one juvenile (fragmentary), and two subfossil carapaces from sands of the fringing reef, Nosy Be , Madagascar .

Dimensions: Specimen 763W: LVL 0.990 mm, LVH 0.630 mm, RVL 0.980 mm, RVH 0.550 mm. Specimen 972F: LVL 0.982 mm, LVH 0.609, RVL 0.972 mm, RVH 0.553 mm. Specimen 2627WM: LVL 0.910, LVH 0.570, RVL 0.900, RVH 0.520 mm.A height:length scatter plot for adult valves was published by Maddocks (1995, Graph 1).

Esophageal Valve: The plate is flat and thin ( Fig. 1M ). The scalloped posterior perimeter curves gently and bears 12 evenly spaced, rounded, mound-like teeth, which increase slightly in size outward from the midline, and which project upward (dorsally) more than posteriorly. The two corner teeth are the same size as the others, bicuspate, and are set apart from the others by a gap. A solitary guide pin rises at a shelf outside each corner from the ventral brush below. The bracket consists of two walls, which converge but do not join anteriorly. The anterolateral scroll is symmetrical, with a semicircular indentation and a curved, spinose projection.

Anatomical Remarks: The high-arched carapace has numerous, nearly circular puncta, aligned in regular, concentric rows, which are smaller in the marginal regions ( Figs. 1O–P ). The pattern becomes coarser centrally, not only because of increasing diameter of the pits but also increasing width of the muri ( Maddocks 1995, Pl. 6, figs. 5-8; Pl. 14, figs. 3-6). The anterodorsal corner and posterior caudal process are slightly thickened, but there is no horizontal bar. Broad fringes may be developed along the anteroventral and posteroventral margins of both valves, which may be worn or eroded in subfossil specimens. The opaque pattern consists of an irregular oval over the MSP, which narrows dorsally and ventrally and does not reach either margin ( Fig. 2F–G ). Smaller spots are located at the anterior and posterior ends.

The anterodistal claw of the adult A2 is almost as long and not quite as thick as the distal claw ( Fig. 1Q ). In the A–1 instar it is represented by a short anlage ( Fig. 1L ).

Figures

FIGURE 1. A–K, Bairdoppilata alcyonicola Maddocks. A–E, molting juvenile specimen 523J: A, RV exterior, showing puncta, sensilla, NPC, inner margin, weakly calcified proximal zone of inner lamella, narrow infold, and marginal frills; ventral edge is damaged; B, posterior caudal angle of RV exterior, showing inner margin, weakly calcified inner lamella, narrow infold, marginal sensilla, and frill; C, anterior margin of RV exterior, with inner margin, weakly calcified inner lamella, infold, marginal sensilla, and frill; D, A2 distal claws, molting; E, zygum and both furcae. F–H, molting juvenile specimen 524J: F, A2 distal claws, molting; G, plate of EV, with uniform row of teeth; H, LV exterior, molting; folded sensilla of new valve are visible beneath old valve. I–K, molting juvenile specimen 168J: I–J, RV and LV exteriors, showing inner margin, broad but weakly calcified inner lamella with continuous vestibules, narrow infold, and characteristic patch pattern; anterodorsal edge of LV is damaged; K, exterior view of posteroventral edge of LV, showing sensilla of new valve folded chevron-style within vestibule of instar. L–Q, Bairdoppilata cratericola Maddocks. O–P, juvenile specimen 973J: L, A2 claws; M, plate of EV. N–Q, adult female specimen 972F: N, genital lobe and spermatophore; O, RV exterior, with low focus to show broad infold, well calcified inner lamella, shallow, separate vestibules, and marginal frills; P, LV exterior, high focus to show puncta, NPC, MSP, and patch pattern; Q, A2 distal claws. Scale bar = 50 µm.

FIGURE 2. A–E, Bairdoppilata alcyonicola Maddocks, adult specimen 764W: A, RV exterior; B, LV exterior; C, RV interior, denticles on anterodorsal edge; D, RV interior, lateral view of hinge, showing ligamental striation on dorsal surface of hinge bar and teeth; E, LV interior, lateral view of hinge, showing ligamental striation on dorsal surface of hinge groove and sockets; arrows point toward anterior. F–H, Bairdoppilata cratericola Maddocks, adult specimen 763W. F, RV exterior, G, LV exterior; H, RV interior, AMS, arrow points toward anterior. Scale bar = 50 µm.