Bairdoppilata cytheraeformis, Hartmann, 1974

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 : 390-391

Bairdoppilata cytheraeformis species-group

The genus Bairdoppilata is ancient and circumtropical, being represented by one or several species in most lowlatitude, shallow-water assemblages since the Cretaceous. The oblong shapes and perfectly smooth carapaces of the species described here are somewhat unusual among living species of the genus, however. Of the 15 species for which the soft anatomy has been described, at least in part ( Maddocks 2022, Table 2 ), the closest in general appearance is Ba. cytheraeformis Hartmann, 1974 from Angola.

Hartmann described the anatomy of living specimens of Ba. cytheraeformis , which were collected from algaecovered rocks on a sand beach at Moçamedes, Angola (1974, p. 251, Pl. 21, figs. 155–162; Pl. 22, figs 163–166). He mentioned that it can tolerate substantial water movement. The valve outlines somewhat resemble Ba. parvafasciata n. sp. but are more elongate, more rounded, with a more nearly level dorsal margin and a less truncate posterior end. Deep anterior vestibules were mentioned. The single posterodorsal opaque spot is a smaller oval. The distal antennal claws of Ba. cytheraeformis are thick, with rounded tips and equal lengths ( Hartmann 1974, fig. 164), quite different from the tapering claws of unequal thickness and length in Ba. magnafasciata ( Fig. 6A ). The stated dimensions of this West African species (L 0.92–1.08 mm, H 0.54–0.58 mm) fall between those for adults of the two Caribbean species, overlapping only a few points at the very top of the RV cluster (but not the LV cluster) of Ba. parvafasciata n. sp. ( Fig. 8 ), and not overlapping at all with the adult cluster of Ba. magnafasciata n. sp. ( Fig. 3 ).

Thus, in the Atlantic Ocean we have a cluster of four rather similar species of Bairdoppilata with smooth, oblong to loaf-shaped carapaces: Ba. cytheraeformis Hartmann, 1974 from Angola; Ba. vitoriensis Da Luz & Coimbra, 2023 from Brazil; and Ba. magnafasciata , n. sp. and Ba. parvafasciata , n. sp. from the mainland coast and islands of the central Caribbean. We may designate this cluster as the Ba. cytheraeformis species-group, which is the only species for which the soft parts have been described.At this time, there is insufficient evidence to determine whether B. fasciata Brady, 1870 [nomen dubium] from the Cape Verde Islands belongs to the Genus Bairdoppilata and should be added to this species-group.

Homeomorphy

Some species of Bythocypris ( Bythocyprididae, Bairdioidea ) have oblong shapes and perfectly smooth carapaces resembling the species of Bairdoppilata described here. They may be distinguished by the generally larger size, the sparse NPC, the characteristic adductor muscle scar (a compact arrangement of four scars, each divided), the absence of bairdoppilatan supplemental dentition, and substantial differences in appendage and genital anatomy ( Maddocks 1969, 1973). Bythocypris is diverse and widely distributed in deeper waters and higher latitudes ( Brandão 2008), but most reports of this genus from tropical coastal waters should be re-examined.

Figures

FIGURE 3. Bairdoppilata magnafasciata, n. sp. H:L scatter plot for 335 specimens, by collecting locality. Dimensions for intact carapaces are included with LVs. Presumed females plot toward the upper right of the adult cluster, and presumed males plot toward the lower left. The dimensions reported by Teeter (1975) plot within the female and male clusters. At least three juvenile instars are represented in these assemblages. The dimensions of illustrated specimens are given in Table 2.

FIGURE 6. Bairdoppilata magnafasciata, n. sp. All female specimen 1030F, from sample Cuba 6. A, distal antennal claws; B, plate of esophageal flapper valve, with bracket; C, genital lobe; D, esophageal valve, with plate, collar, and both braces; E, LV interior; F, H, RV exteriors; G, I, LV exteriors; J–K, anterior and posterior ends of RV to show ligamental striations of hinge and weak supplemental dentition; L–M, anterior and posterior ends of LV to show supplemental dentition. A–G, J–M, in transmitted light; H–I, in reflected light. Bar scale = 100 micrometers.

FIGURE 8. Bairdoppilata parvafasciata, n. sp. H:L scatter plot for 226 specimens, by collecting locality. Dimensions for intact carapaces are included with LVs. Presumed females plot toward the upper right of the adult cluster, and presumed males plot toward the lower left. Adult and three juvenile instars are represented in these assemblages. The dimensions of illustrated specimens are given in Table 3.