Taxonomic applications of the esophageal flapper valve in Bairdoppilata and Glyptobairdia (Bairdiidae, Ostracoda), with comments on anatomy, ontogeny, and geography Author Maddocks, Rosalie F. text Zootaxa 2022 2022-08-17 5175 3 301 342 journal article 124035 10.11646/zootaxa.5175.3.1 509d2bb8-bdff-4757-b45a-5d0cbccc31b4 1175-5326 7003585 44FB9C3D-3188-4BFB-BDB8-C1324729A396 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. 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. 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 ).