Glyptobairdia coronata (Brady, 1870)

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 : 331-335

Glyptobairdia coronata (Brady, 1870)

( Figs.17 , 18A–H , 19A–L )

1870 Bairdia coronata Brady , n. sp.: p. 243, pl. 32, fig. 9.

1946 Glyptobairdia bermudezi Stephenson , n. sp.: p. 346, pl. 42, figs. 1–3.

1947 Triebelina coronata (Brady) .—Stephenson, p. 578.

1954 Triebelina coronata (Brady) .—Keij, p. 330, pl. 4, fig. 2.

1958 Triebelina coronata (Brady) .—Morkhoven, p. 366, pl. 46, figs. 1–6.

1960 Triebelina coronata (Brady) .—Rome, p. 1–14, figs. 1A–H, 2A–S, 3A–D, 4A–L.

1960 Triebelina coronata (Brady) .— Puri, p. 131, pl. 6, figs. 1–2.

1963 Triebelina coronata (Brady) .— Morkhoven, 1963, figs. 44a–b.

1969 Bairdoppilata (Glyptobairdia) coronata (Brady) .—Maddocks, p. 84, figs. 44A–G.

1971 Glyptobairdia coronate (Brady) .—Bold, p. 336, pl. 3, fig. 6.

1974 Glyptobairdia coronata (Brady) .—Bold, p. 33.

1975 Bairdoppilata (Glyptobairdia) coronata (Brady) .—Teeter, p. 421, figs. 3h, 4f.

1976 Glyptobairdia coronata (Brady) .— Keij, 1976, p. 37, table 1.

1977 Glyptobairdia coronata (Brady) .—Bold, table 2, p. 182.

1982 Bairdoppilata (Glyptobairdia) coronata (Brady) .—Krutak, table 2, p. 164, pl. 1, figs. 9–18.

1983 Bairdoppilata (Glyptobairdia) coronata (Brady) .—Palacios-Fest et al., table 1, pl. 1, fig. 5.

1986 Glyptobairdia coronata (Brady) .—Maddocks & Kornicker, p. 386, fig. 91.

1986 Glyptobairdia coronata (Brady) .—Maddocks & Iliffe, p. 57, table 2.

1988 Glyptobairdia coronata (Brady) .—Malz & Lord, p. 70, pl. 3, figs. 1–3.

1988A Glyptobairdia coronata (Brady) .—Bold, table 1, p. 146; table 2, p. 150.

2000 Glyptobairdia coronata (Brady) .—Keyser & Schöning, p. 569, pl. 2, fig. 33.

2009 Glyptobairdia coronata (Brady) .—Maddocks et al., p. 888 (Checklist).

Material: Approximately 90 subfossil valves from the Bahamas, Bermuda, Belize, Cuba, Florida, Grand Cayman Island, Honduras, Vera Cruz, and the U.S. Virgin Islands.

Dimensions: Male specimen 2441M, LVL 0.817, LVH 0.477, RVL 0.806 mm, RVH 0.406 mm. In Fig. 18 , some differences in size may be perceived among these geographic populations. In general, specimens from Bermuda and Vera Cruz are larger, while those from Florida are smaller. So far as known, females are longer than males and higher in proportion to length.

Anatomical Remarks: The oval ridge on the lateral field of each valve is well defined, continuous, with a slightly rippled course in the posterodorsal region, but no gaps. The crest of this ridge is occupied by a chain of NPC with short, thick sensilla ( Figs. 18G–H ). A short horizontal bar is located within the level field enclosed by this loop, which is nearly straight in the RV and weakly arched (concave-down) in the LV. Thin spurs diverge from the ridge to become muri. Well-defined horizontal ridges at the anterior and posterior ends connect with the oval lateral ridge. The central field has a complex reticular pattern of thin muri and oval to polygonal fossae with stippled floors. None of the numerous intact and fragmentary specimens of G. coronata examined for this project, from multiple localities and of various degrees of conservation, show gaps in the ridges or any tendency toward development of nodes resembling those of G. trinodosa .

As Morkhoven (1963) pointed out, the hinge is strongly developed, with smooth terminal teeth, and all elements show fine crenulation. This crenulation is ligamental rather than articulatory in function and does not have taxonomic significance.

Excellent SEM images of adults of G. coronata were published by Krutak (1982, pl. 1, figs. 9-18, including dramatic dorsal, ventral, anterior and posterior views of the intact carapace) and by Malz & Lord (1988, pl. 3, figs. 1–3, including hinges and supplemental dentition).

Bold (1974, p. 31) doubted whether juveniles of ornate bairdiids can be distinguished from those of co-occurring, less ornate genera, pointing out that “I have nearly always found only adult specimens of Glyptobairdia and Triebelina , with fully developed marginal areas, never molts (except perhaps in the case of the last immature instar).”

Here, photographs of the A–1 and A–2 instars of G. coronata are published for the first time ( Figs. 19 A-L). These juvenile specimens are from a subfossil assemblage in the Florida Keys, which yields abundant adults of G. coronata , but none of G. trinodosa . They somewhat resemble the instars of a punctate species of Bairdoppilata [identified by Puri (1960) as “ Bairdia milne-edwardsi (Brady) ” and by Benson & Coleman (1963) as “ Bairdia cf. B. bradyi Bold ”], which is common in the same assemblage. Nevertheless, they may be discriminated by their more angular, quadrate to hexagonal, broad-shouldered lateral outlines ( Figs. 20 A-L). In particular, they are slightly longer through the mid-dorsal section, between the anterodorsal and posterodorsal corners, which are more distinctly marked ( Figs. 19B, I, K–L ) than in species of Bairdoppilata .

These juvenile valves are thin-walled and fragile but densely punctate, with polygonal to oval puncta linearly arrayed between narrower muri ( Figs. 19A–F, H–L ). No exterior ridges are developed, and the carapace wall is not thickened near the anterodorsal corner and caudal process. The caudal process, which is conspicuous but narrowly pinched at its base in adults, is broader at its base in these instars, longer in proportion to valve length, and tapers sinuously ( Figs. 19E–G, J ). Instead of the long, heavily calcified marginal denticles and corrugated frill of the adults, the instars have only thin, discontinuous, zig-zag laminae near the perimeter ( Figs. 19E–G ). Bairdoppilatan dentition is foreshadowed in the A–1 RV by a slight thickening and roughening of the valve edge, in the location where supplemental denticles will develop in the adult ( Fig. 19G ). In the A–1 LV no corresponding locules are visible, and the infold is too narrow in this area to accommodate them ( Figs. 19D, F ). No calcified inner lamella is preserved in these subfossil valves.

Geographic Distribution: This species was described by Brady (1870) from reefs off Vera Cruz in the western Gulf of Mexico, where it was also reported by Krutak (1982). Stephenson (1946) described it (as G. bermudezi ) from recent sediments at La Chorrera, Havana, Cuba. Puri (1960) reported it from Molasses Reef off Tavernier Island in Florida Bay, and off Key Largo in the Florida Keys. Rome (1960) described and illustrated the soft parts of living specimens, including the esophageal valve, which were collected from St. Barthelmy Island in the Lesser Antilles. The description by Maddocks (1969) was based on material collected by Louis S. Kornicker from Andros Island in the Bahamas. Teeter (1975, Table 1 ) collected a total of 8 specimens at 4 stations on the carbonate platform of Belize. Bold (1974; 1988A, Table 2 ) summarized its distribution: Alacran Reef, Belize, Cozumel, Cuba, Hispaniola, Nicaragua, Panama, Puerto Rico, Tobago, northern Venezuela, the Lesser Antilles, and the Caribbean.

Additionally, in the material examined for this report, it occurs in near-reef sediments of Bermuda, the Bahamas, the Florida Keys, and Roatan Island (Bay Islands, Honduras). It is absent from the western shelf of the Yucatan Peninsula, the Bay of Campeche, and the Flower Gardens on the shelf-edge of Texas. In all assemblages it is relatively rare, being characteristic of stations near the reef front rather than the lagoon or back-reef platform. Bold (1974, p. 33) stated that G. coronata has a stratigraphic range of Pleistocene to recent, citing a fossil occurrence in the Manchioneal Formation of Jamaica.

Figures

FIGURE 17. Glyptobairdia coronata (Brady). H:L scatter plot for 290 subfossil specimens from 10 Caribbean localities. Because of extreme valve asymmetry, two elongate diagonal clusters are evident: the upper cluster includes 180 LV and carapaces, and the lower cluster represents 110 RV. Adult females tend to plot at the upper right of each cluster, while males plot at the lower left. Separate clusters for instars A–1 and A–2 are represented in the Florida assemblages. In general, specimens from Bermuda tend to be larger, and those from Florida smaller, than those at other localities.

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.

FIGURE 19. Glyptobairdia coronata (Brady), juvenile subfossil specimens from Florida. A–G, specimen 4078WJ, A–2 instar: A, C, E, RV exteriors in transmitted light, showing alignment of punctate ornament, elongate caudal process, terminal spinule, and tiny, irregular posteroventral frill; B, D, F, LV exteriors in transmitted light, showing alignment of punctate ornament, with marginal spinule at anterodorsal corner, zig-zag edges of incipient posteroventral frill, and sinuate caudal process; G, RV exterior in transmitted light, showing sinuate caudal process, with small terminal spinule and zig-zag posteroventral frill; incipient bairdoppilatan dentition is developed as six tiny denticles (or granules) on bend of posterodorsal edge. H, J, specimen 4077RVJ, A–1 instar: RV exterior in transmitted light, showing alignment of punctate ornament, darker NPC, AMS, narrow infold, and absence of calcified inner lamella. I, K–L, specimen 4076LVJ, A–1 instar: LV exterior in transmitted light, at high and low focus, to show delicate network of aligned punctate ornament, darker NPC, AMS, narrow infold, and absence of calcified inner lamella. Scale bar = 50 µm.

FIGURE 20. Glyptobairdia trinodosa Teeter. H:L scatter plot for 19 adult subfossil specimens (1 carapace, 8 LV, 8 RV) from 2 localities. Because of extreme valve asymmetry, LV plot in the upper cluster and RV plot in the lower cluster. Without soft–part control, sexual dimorphism cannot be verified, although it is likely that the longer specimens are females.