Bairdoppilata, Coryell, Sample and Jennings, 1935

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 : 309-310

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.

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.

FIGURE 5. Bairdoppilata cushmani (Tressler), male specimen 3114M from the Bahamas, UH2371. A, plate, bracket and fragment of ring; B, brace; C, intact right hemipenis and incomplete left hemipenis; D, copulatory tube, distal element, and appendages of right hemipenis; E, copulatory tube, distal element, and appendages of left hemipenis; F, A2 distal claws; G–H, right and left valve exteriors in transmitted light, showing patch pattern, NPC, marginal sensilla, broad infold and shallow vestibules; linear tracks are probably postmortem agal or fungal borings; I–J, right and left valve exteriors in reflected light, showing patch pattern and smooth, reflective surface. Scale bar = 50 µm.

FIGURE 6. Bairdoppilata cushmani (Tressler), male specimen 1651M from the Bahamas. A–B, distal claws of both A2; C–D, esophageal valve with ring, belt, collar, plate and bracket, at higher focus for belt and corner teeth, and at lower focus for bracket and medial teeth; E, plate and bracket; F, both braces; G–H, both hemipenes; I, posteroventral fragment of decalcified RV exterior, showing posterior angle and ventral margin with RPC, marginal frill, and sensilla; arrow points to anterior; J, posterodorsal fragment of decalcified LV exterior, showing crenulation of hinge; also parts of food ball, testes, and seminal vesicles; arrow points to anterior; K, left lateral view of mouth region, showing spinules around sclerotized edge of upper lip, and ciliate hemispherical mound within lower lip, with flagellate seta projecting into atrium; L, ciliate hemispherical mound of lower lip, with flagellate seta projecting into atrium. Scale bar = 50 µm.

FIGURE 7. Bairdoppilata cushmani (Tressler). A–F, male specimen 1648M from the Bahamas: A–B, right and left hemipenes; C–D, details of distal element, copulatory tube, and appendages of right and left hemipenes; E, RV exterior in reflected light, showing nearly smooth surface with NPC and sensilla; F, RV exterior in transmitted light, showing NPC, patch pattern, and sensilla. G–J, juvenile carapace 4082WJ, instar A–2: G–H, RV and LV exteriors in transmitted light, showing patch pattern and NPC; I–J, RV and LV exteriors in reflected light; showing patch pattern and NPC. K–N, juvenile carapace 4081WJ, instar A–1: K–L, RV and LV exteriors in transmitted light, showing patch pattern and NPC; M–N, RV and LV exteriors in reflected light; showing patch pattern and NPC. Scale bar = 50 µm.

FIGURE 8. Bairdoppilata cushmani (Tressler). A–P, female specimen 2395 from Florida: A, B, left and right A2 distal claws; C, anterodorsal view of head capsule and midgut during dissection, with food ball, esophageal valve with ring, collar, belt, plate, and both braces, forehead, upper and lower lips, and sternum; D, food ball, showing spiral structure; E–F, spermatophores; G, plate, bracket, and both braces; H, posterior teeth of plate; I–J, RV and LV exteriors in transmitted light, showing patch pattern, NPC and sensilla; K–L, RV and LV exteriors in reflected light, showing patch pattern, NPC, and smooth surface; M–N, anterodorsal and posterodorsal edges of RV interior showing supplemental denticles; O–P, anterodorsal and posterodorsal edges of LV interior showing supplemental locules on infold beneath dorsal overhang. Scale bar = 50 µm.

FIGURE 9. Bairdoppilata cushmani (Tressler). A-S, male specimen 2399M from Florida: A, esophageal valve with collar, plate and bracket; B–C, braces; D–F, dorsal views of left hemipenis; D, entire left hemipenis; E, terminal details of left hemipenis, including distal element, copulatory tube, and appendages; F, two cilia of bifurcate tip of copulatory rod within tip of tube; G–H, fragmentary right hemipenis, with distal element, fragmentary copulatory tube, and appendages; I, left lateral view of lower lip, showing ciliate hemispherical mound with flagellate seta projecting into atrium, T–bar strut, and ventral setules of sternum; J–K, RV and LV exteriors in transmitted light, showing patch pattern, NPC and sensilla; L–M, RV and LV exteriors in reflected light, showing patch pattern, smooth surface, and widely spaced NPC; N–O, anterodorsal and posterodorsal edge of RV interior to show denticles of supplemental dentition; P–Q, posterodorsal and anterodorsal edges of LV interior, showing locules of supplemental dentition, located on infold beneath dorsal overhang; R–S, RV and LV exteriors in transmitted light, with AMS, NPC, occasional sensilla, and texture of smooth surface. Scale bar = 50 µm.

FIGURE 10. Bairdoppilata cushmani (Tressler). A–G, female specimen 1026F from Cuba 6: A, esophageal valve with collar, plate, bracket and tuberculate ends of braces; B, posterior teeth of plate, with a few smaller nodes visible between teeth; C, genital lobe; D– E, RV and LV exteriors in transmitted light, to show patch pattern and setules; F–G, RV and LV exteriors in reflected light to show patch pattern and smooth surface. Scale bar = 50 µm.

FIGURE 12. Bairdoppilata hirsutella Maddocks, n. sp. A–C, molting juvenile specimen 689J, USNM 139894, instar A–1: A, LV interior in reflected light, with narrow infold, broad but weakly calcified inner lamella, and vestibules partly filled with fluid; B, LV interior in reflected light, with AMS, showing striated, hummocky texture of inner chitinous lining, as sensilla and cuticle are being withdrawn from older valve; C, anterior margin of RV interior in reflected light, showing narrow (normal) infold. D–K, holotype adult male specimen 634M, USNM 139891: D–E, LV and RV interiors in reflected light, with broad calcified inner lamella, shallow vestibules separated ventrally, prominent selvage and fringes; F, RV interior, posterodorsal edge with denticles of supplemental dentition; G, LV interior, posterodorsal edge with locules of supplemental dentition beneath dorsal overhang; H–I, RV and LV exteriors in transmitted light, with broad (normal) inner lamellae, fairly deep vestibules, NPC, sensilla, and AMS; J–K, RV and LV exteriors in reflected light, showing smooth surface and sensilla; RV caudal process is damaged. L–M, adult female specimen 635F, USNM 139892: RV and LV exteriors in transmitted light, with AMS and sensilla. Scale bar = 50 µm.

FIGURE 13. Bairdoppilata hirsutella Maddocks, n. sp. A–D, holotype adult male specimen 634M, USNM 139891: A, dorsal view of zygum, both furcae, and left hemipenis; B, distal element, copulatory tube, and terminal appendages of left hemipenis; C, dorsal view of esophageal valve with ring, collar, belt, plate, and both braces; D, A2 distal claws. E, adult female specimen 635F, USNM 139892: genital lobe. F, molting juvenile specimen 689J, USNM 139894, A–1: detail of antennal claws to show how ramus and claws are withdrawn during molting. Scale bar = 50 µm.

FIGURE 14. Bairdoppilata hirsutella Maddocks, n. sp. A, molting juvenile, female A–1, specimen 689J, USNM 139894: posterior region of body with zygum, genital lobes, furca, and postabdominal seta. Scale bar = 50 µm.

FIGURE 15. A–I, Bairdoppilata sp. 2 [of Morais & Coimbra 2017, Brazil]. A–D, female specimen 3991F: A, right exterior of whole animal before dissection, in transmitted light, with median eye in anterodorsal region, immature eggs in posterodorsal region; B, LV exterior, damaged, showing AMS and sensilla; C, LV exterior, with AMS and sensilla; D, A2 distal claws. E–G, female specimen 3987F: E, A2 distal claws; F, left side of soft body before dissection, with large median eyes, food balls in gut, and eggs in oviducts; G, genital lobe. H–I, female specimen 3988F: H, LV interior, torn, with AMS and sensilla; I, LV interior, showing AMS and texture of smooth valve. J–L, Bairdoppilata martyni Coryell, Sample and Jennings [Oligocene, Mississippi]: J–K, specimen 1018RV: J, RV exterior in reflected light, showing patch pattern, note occasional clear circles around largest NPC; K, RV exterior in transmitted light, showing patch pattern and NPC. L, specimen 1019LV: LV exterior in transmitted light, showing patch pattern, note occasional clear circles around largest NPC. Scale bar = 50 µm.

FIGURE 16. A, B, Bairdoppilata scaura Maddocks [Hawaii]: A, male specimen 3860M: esophageal plate. B, male specimen 3864M: left lateral view of mouth region, with upper and lower lips, atrium, esophagus, U–shaped strut of upper lip, ciliate hemispherical mound of lower lip, flagellate seta projecting into atrium, and setules of forehead and sternum. C, Bairdoppilata sp. 2 [of Maddocks 2015, Hawaii]: female specimen 3969F: esophageal valve with ring, collar, belt and plate. D, Bairdoppilata sp. 3 [of Maddocks 2015, Hawaii]: female specimen 3923F: esophageal valve with collar, plate, bracket, and basal ends of braces. E, Bairdoppilata sp. 4 [of Maddocks 2015, Hawaii]: female specimen 3963F: esophageal plate with bracket. F–I, Bairdoppilata sp. 2 [of Morais & Coimbra 2017, Brazil], female specimen 817F: F, A2 claws; G, esophageal plate and bracket; H, both braces; I, genital lobe. Scale bar = 50 µm.

FIGURE 18. Glyptobairdia coronata (Brady), male specimen 2441M from Bermuda. A–B, RV and LV exteriors in transmitted light, showing hexagonal lateral outlines with well–marked corners, narrowly extended caudal processes, and densely punctate ornament with central ridges, marginal denticles and frills, and sensilla; C, dorsal view of both hemipenes and zygum; D–E, dorsal views of right and left hemipenes, with bifurcate tip of coiled copulatory tube, setulose distal appendage, distal element, and other appendages; F, distal claws of A2; G–H, RV and LV exteriors in transmitted light, showing details of punctate ornament, with central ridges, sensilla along crest of ridge, polygonal puncta with stippled floors, narrow muri, NPC, and AMS. Scale bar = 50 µm.