Bairdoppilata parvafasciata, Maddocks & Horne, 2024

Maddocks, Rosalie F. & Horne, David J., 2024, “ What’s in a name? ” Bairdia fasciata Brady, 1870, and two new Caribbean species of Bairdoppilata (Bairdiidae, Podocopida, Ostracoda), Zootaxa 5448 (3), pp. 371-400 : 384-389

publication ID	https://doi.org/ 10.11646/zootaxa.5448.3.3
publication LSID	lsid:zoobank.org:pub:6907E847-FE33-47AD-9F0A-B8AF763515A8
DOI	https://doi.org/10.5281/zenodo.11243077
persistent identifier	https://treatment.plazi.org/id/6A3587F7-6E40-FFC9-FF1F-985DAAC1FAF1
treatment provided by	Plazi
scientific name	Bairdoppilata parvafasciata
status	sp. nov.

Treatment

Bairdoppilata parvafasciata , n. sp.

( Figs 8 View FIGURE 8 , 9A–S View FIGURE 9 , 10A–V View FIGURE 10 ; Tables 1 View TABLE 1 , 3 View TABLE 3 )

Not 1870 Bairdia fasciata n. sp. —Brady, 193, pl. 19, figs. 20, 21.

Not 1975 Bairdoppilata (Bairdoppilata) fasciata (Brady) —Teeter, p. 420, figs. 3g, 4e [= Ba. magnafasciata n. sp.]

? 1982 Bairdia gerda Benson and Coleman —Llano, p. 77, Pl. 1, fig. C 1.

? 2021 Bairdoppilata sp. 1 —Bernal, p. 57, Pl. 7, figs. 23–26.

Material Examined: 254 subfossil valves and carapaces.

Types: Holotype specimen 4084LV, USNM 1607074 View Materials , a dry LV, presumed female, from Belize, sample 2742 . Paratype specimen 4085 RV, USNM 1607075 View Materials , a dry RV, sex indeterminate, from the same sample, Belize .

Type locality: Belize carbonate shelf, near Caye Chappel , western Caribbean Sea.Approximate Lat. 17 o 41’44”N, Long. 88 o 02’19”W. 300–400 feet (91–122 meters) from shore, windward side of island, inside of barrier reef. Water depth 20–25 feet (6–8 meters) GoogleMaps .

Derivation of Name: Latin, parvus, small; plus fasciatus, banded, striped, bundled.

Dimensions: Holotype specimen 4084LV, USNM 1607074 View Materials : L 0.897 mm, H 0.535 mm. This specimen plots within the upper part of the adult LV cluster ( Fig. 8 View FIGURE 8 ) and is likely to be a female. Paratype specimen 4085 RV, USNM 1607075 View Materials : RV L 0.907 mm, H 0.498 mm. This specimen plots near the middle of the adult RV cluster ( Fig. 8 View FIGURE 8 ) and could be either sex. The dimensions for all illustrated specimens are given in Table 3 View TABLE 3 .

The H:L scatter plot ( Fig. 8 View FIGURE 8 ) shows evident size dimorphism, with presumed females being both longer and higher than males but similar in shape. This is a common pattern in bairdiids.

Occurrence: Belize, Cozumel, Cuba, Grand Cayman, and Roatan ( Table 1 View TABLE 1 ). The species has been sought but not seen in assemblages from the Bahamas, Bermuda, Jamaica, the Florida Keys, and the Flower Gardens in the Gulf of Mexico. Apparently, the species was not recognized by Teeter (1975) in his Belize assemblages.

A LV of this species may have been illustrated from the Bay of Cartagena, Columbia, by Llano (1982, Pl. 1, fig. C 1 misidentified as Neonesidea gerda ).

Bernal (2021, p. 57, Pl. 7, figs. 23-26) may have reported this species as “ Bairdoppilata sp. 1 ” from the lagoon of Serrana Atoll (78 specimens in 21 samples from an 80-cm sediment core). The dimensions provided (LV L 0.85 mm, H 0.51 mm; RV L 0.85-0.88 mm, H 0.47-0.49 mm) plot within the lower end of the respective clusters for P. parvafasciata ( Fig. 3 View FIGURE 3 ). Serrana Bank GoogleMaps is an underwater atoll and coral reef, located on the continental slope of Nicaragua but administered by Columbia GoogleMaps , at 14 o 20’N, 80 o 20’W. It is included within the UNESCO Seaflower Biosphere Reserve (https://en.unesco.org/biosphere/lac/seaflower).

Description: Carapace smooth, oblong to loaf-shaped in lateral outline ( Figs 9B, L, P View FIGURE 9 ), highest slightly anterior to mid-length in lateral view at smoothly curving anterodorsal angle; mid-dorsal margin short; posterodorsal angle broadly rounded but definitely indicated; posteroventral margin sloping steeply; ventral margin nearly level, with broad but very shallow ventral indentation.There is substantial overreach of LV over RV along dorsal and posterodorsal margins, less along anterodorsal and midventral margins, and none along anteroventral and posteroventral margins. In dorsal view the carapace is inflated medially, thickest at mid-length, with moderately rounded anterior end and gently curved sides; posterior to this central swelling, both valves are constricted, but the RV is more so, just in front of the narrowly rounded posterior end ( Figs 9C, N, R View FIGURE 9 ).

Lateral outline of LV high-arched, upright, asymmetrical, with broadly but obliquely rounded anteroventral margin, long and weakly curved anterodorsal margin, short and sloping mid-dorsal margin, steeply sloping posterodorsal margin, obliquely up-curving posteroventral margin, and gently indented ventral margin ( Figs 9D, I View FIGURE 9 ; 10B, D, F, O–P, T, V View FIGURE 10 ). Anterodorsal and posterodorsal angles obtuse, broadly rounded but distinct; posterior angle obtuse but well defined, slightly caudate, emphasized by slight sinuosity of dorsal margin just above posterior angle. Lateral outline of smaller RV necessarily more angulate, with more clearly indicated anterodorsal, posterodorsal, and posterior angles, well-marked anteroventral angle, and shallow but consistent ventral indentation ( Figs 9A, H View FIGURE 9 ; 10A, C, E, N, S, U View FIGURE 10 ).

Hinge bairdiid, with no special features, all elements narrow because of the thin carapace wall ( Fig. 9E View FIGURE 9 ). Supplemental bairdoppilatan dentition consists of about 6 small denticles on anterodorsal and posterodorsal edge of the RV; the LV has about 6 small locules on infold beneath anterodorsal and posterodorsal overhangs ( Figs 9F, G View FIGURE 9 ). The supplemental denticles are hard to see, because the valve edge is thin, hardly widened in this region, and the denticles are not much larger than the striated texture of the valve wall. In the LV, the row of locules is located in the crease right under the overhang, only visible if the valve is tilted, and the usual swelling of the infold ventral to the locules is poorly developed.

Valve margins smooth, without marginal spines. Marginal infold of moderate breadth with anterior and posteroventral vestibules. NPC and false RPC numerous, radiating laterally outward and superposed near margins. Adductor muscle scar pattern bairdiid, with about 9 scars arranged in 3 rows in a loose rosette.

Each valve has a distinctive patch pattern of clear and opaque regions. In the LV the central opaque spot (1) is large and shield-shaped, with a nearly flat top; an irregular posterodorsal extension connects with the mid-dorsal spots ( Figs 9D, I View FIGURE 9 ; 10B, D, F, O–P, T, V View FIGURE 10 ). Within the anterodorsal part of the central opaque spot a tiny transparent oval is consistently present, and the region over the muscle scars may be somewhat more transparent. The lower tip of the central spot may extend almost to the ventral indentation, or that ventral region may be clear. Other opaque spots in the LV include (2) a large, triangular posterodorsal spot, which extends to the posterodorsal margin; (3) smaller circular or irregular spots at the anterior and posterior angles; and (4) two small mid-dorsal spots, which may connect to the posterodorsal extension of the central spot by peninsulas or islands. In the RV the pattern of spots is similar, nearly symmetrical ( Figs 9A, H View FIGURE 9 ; 10A, C, E, N, S, U View FIGURE 10 ). In less well conserved specimens the pattern is more difficult to discern, because of post-mortem cloudiness, abrasion and corrosion. The patch pattern is easily recognizable in late juvenile instars, which have smaller but more sharply defined spots and more transparent surrounding fields Figs 9J–K View FIGURE 9 ; 10G–M View FIGURE 10 ).

The soft parts are unknown.

Comparisons: Bairdoppilata parvafasciata n. sp. is similar to B. magnafasciata , which also occurs in these assemblages ( Table 1 View TABLE 1 ). It differs by its smaller size, more upright and broad-shouldered lateral outline, more distinct posterodorsal angle, more truncate posterior margin, more caudate shape and lower placement of the posterior angle, and the triangular shape of the large posterodorsal opaque spot.

From Ba. cushmani Tressler, 1949 , which has a somewhat similar lateral outline and occurs abundantly throughout the Caribbean ( Maddocks 2022), it may be distinguished by its smaller size, less angulate lateral outline, the less exaggerated caudal angle, and the single posterodorsal spot (rather than two spots).

Late juvenile instars of these three species can be separated by careful attention to the opaque spots. The differences of shape are less marked in the juveniles.

Bairdoppilata parvafasciata resembles Ba. cytheraeformis Hartmann, 1974 , described from the coast of Angola. It is smaller, with less elongate proportions, a less rounded lateral outline, a slightly more convex dorsal margin, and a more distinctly truncate posterior end.

Bairdoppilata parvafasciata somewhat resembles Ba. vitoriensis Da Luz & Coimbra, 2023 , described from the coast of Brazil. It is substantially smaller and not as high relative to length. In lateral outline it is less exaggerated, with less elevated dorsal margin and a less abruptly truncated posterior end.

Remarks: No geographic trends are evident in size or shape, apart from likely sexual dimorphism ( Fig. 8 View FIGURE 8 ).

Bairdoppilata parvafasciata is the smaller of the two Caribbean species,the larger species being Ba.magnafasciata n. sp. (see above). It is represented in 17 of the 29 assemblages studied here, but in less total abundance than Ba. magnafasciata ( Table 1 View TABLE 1 ). It tends to occur in the coarser sands and coralline rubble near a reef tract, rather than in the shallow-water sands of quieter platform and lagoonal environments.