Bairdoppilata Coryell, Sample and Jennings 1935
Creators: name: Maddocks, Rosalie F.
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Ostracoda
Podocopida
Bairdiidae
Bairdoppilata

description: Genus BAIRDOPPILATA Coryell, Sample and Jennings, 1935
1935 Bairdoppilata Coryell, Sample and Jennings: 3.
1963 Bairdia M’Coy. —Morkhoven, p. 32 [part].
1969 Bairdoppilata (Bairdoppilata) Coryell, Sample and Jennings. —Maddocks, p. 66.
1995 Bairdoppilata Coryell, Sample and Jennings. —Maddocks, p. 215.
Type species: Bairdoppilata martyni Coryell, Sample & Jennings, 1935 was described from the Chickasawhay Formation of Mississippi (Oligocene).
Species Included: The soft anatomy has been described, at least in part, for only 15 named species of Bairdoppilata (Table 2), although others have been designated in open nomenclature. Before this report, the esophageal valve had been illustrated for only two of those species.
Anatomical Remarks: For living species, the genera Bairdoppilata and Glyptobairdia (so far as known) are identified by seven key anatomical traits:
(1) Supplemental dentition is developed on the anterodorsal and posterodorsal margins of the valves (Figs. 2C, 8M–P, 9N–Q, 12F–G).
(2) The anterodistal seta of the A2, which is a slender seta in other genera, is a large claw (1Q, 5F, 6A–B, 8A–B, 13D, 15E, 16F, 18F). In adults of most species, this claw is almost as long and thick as the main distal claw, resembling a scissors blade. This claw emerges only at the last (pre-adult) molt, and it is represented in instars by a fusiform anlage (Figs. 1A, O, 14F).
(3) The fused claw of the A2 is smooth or undulate, rather than barbed, serrate or pectinate (Figs. 1Q, 6F, 6A–B, 8A–B, 13D, 15E, 16F, 18F).
(4) The vibratory plate of the fifth limb has four segregated setae in both sexes (a trait shared also by Paranesidea and some other genera).
(5) The furca has seven setae of medium and long lengths (Fig. 1E, 13A, 14A).
(6) The hemipenis has a complex distal configuration, with several appendages on the medial and terminal elements, which may have locking, sensory and protective functions (Figs. 5C–E, 6G–H, 7A–D, 9D–H, 13A–B, 18 D-E). On an erect specimen these processes are clearly visible and offer taxonomic information. In non-erect specimens, these processes are folded down and overlap, and it is difficult to see details. The copulatory rod is confined within a fairly long, arcuate tube (Figs. 5C–E, 6G–H, 7A–D, 9D–H, 13A–B, 18D–E) and ends in a slender tip with two delicate processes (Fig. 9F).
(7) The configuration of the esophageal flapper valve contributes a seventh unifying trait for Bairdoppilata. The plate is relatively thin and wedge-shaped, with a curved, multidentate posterior margin, where a series of nodes or low teeth project dorsally and posteriorly (Figs. 1G, M; 5A; 6C–E; 8G–H; 9A; 10A–B). The array is notable for the large number and evenness of the teeth, which are all about the same size and arranged in a single marginal row. The plate of Glyptobairdia coronata, as illustrated by Rome (1960, Fig. 2D), conforms to the same pattern.
This delicately serrate profile is easily distinguished from the smooth-edged, toothless plate of some other bairdioid genera (Aponesidea, Havanardia, Mydionobairdia, Triebelina, and a few species of Neonesidea). It resembles the pattern that is common in typical species of Neonesidea, except that the teeth are more numerous (12–18, compared with 6–10 in Neonesidea), smaller, and more nearly equal in size. The dorsal surface of the plate is apparently smooth, not tuberculate (as in Bythocypris) or spinose (as in Paranesidea).
The chitin framework of the mouth region (forehead, upper lip, atrium, lower lip, sternum) in Bairdoppilata is similar to that described for Neonesidea (Maddocks 2015, 2018). A hemispherical swelling on the atrial surface of the lower lip, ringed with concentric rows of tiny cilia and surmounted by a flagellate seta, protrudes centrally into the atrium (Figs. 6K–L, 9I). That flagellate seta has been seen in species of Neonesidea and Paranesidea, as well, and should be looked for in other genera. The taxonomic value of the head capsule has not been investigated for Bairdiidae, although some special adaptations are expressed in the flexible jaws of Pussellidae (Pussella, Anchistrocheles, Bythopussella).
Taxonomic Remarks: Bairdoppilata is an ancient genus. Fossil species, recognized by supplemental dentition on the anterior and posterior ends of the dorsal overhang, are reported in Jurassic, Cretaceous and Cenozoic faunas. Kempf (1986, 1995, 2004) listed more than 100 nominal species. Today, it is global and represented by one or several species in most assemblages. The WoRMS database includes 39 species, most of which are Holocene or Neogene (Brandão & Karanovic 2021).
The subgenera proposed by Maddocks (1969) proved to be cumbersome and unnecessary, and they should be ignored (as recommended by Maddocks 1995). Glyptobairdia is more appropriately ranked as a separate genus. The restriction of Bairdoppilata to low-latitude, shallow-water forms (suggested by Maddocks 1969) is not sustainable. No distinction should be made (by use of a question mark) for species collected from high latitudes or deep water, unless supported by morphological attributes.
description: Published as part of Maddocks, Rosalie F., 2022, Taxonomic applications of the esophageal flapper valve in Bairdoppilata and Glyptobairdia (Bairdiidae, Ostracoda), with comments on anatomy, ontogeny, and geography, pp. 301-342 in Zootaxa 5175 (3) on pages 309-310, DOI: 10.11646/zootaxa.5175.3.1, http://zenodo.org/record/7003585