Bulbocythere calida, Coimbra, João Carlos & De Morais, Anderson L. M., 2016

Coimbra, João Carlos & De Morais, Anderson L. M., 2016, On a new marine podocopid genus and species (Ostracoda: Hemicytheridae) from Brazil, Zootaxa 4193 (1), pp. 167-176 : 170-173

Bulbocythere calida sp. nov.

Fig. 3 : 1−18

1992 Echinocythereis ? sp.—Coimbra et al., p. 98–102, pl. 2, fig. 12, tabs. 1–4.

2008 Gen. et sp. indet.—Machado, p. 184–186, pl. 8, figs. 12–14, tabs. 4, 6 and 9.

Type series. Holotype: MP-O-1396, adult female, LV. Paratypes: MP-O-2584, juvenile female, C; MP-O-2585, juvenile male, C; MP-O-2586, juvenile female; MP-O-2587, juvenile male, C; MP-O-2588, adult male, RV.

Type locality. Tamandaré Bay (8°45’S, 35°06’W), Pernambuco State, Northeastern Brazil.

Etymology. Latin origin, calidus = warm, because of its distribution being restricted to warm waters.

Material. 33 carapaces and 17 valves, of which only two well-preserved valves and one eroded carapace are from adults.

Dimensions. See table 2.

Description. Carapace medium sized, thick-shelled and subrectangular in lateral view. Posterior cardinal angle conspicuous, mainly in LV. Maximum height anteriorly. In dorsal view, inflated-ovate. Maximum width just behind mid-length. Anterior margin rounded, with an antero-dorsal flange in LV. Posterior margin dorsally concave and convex ventrally, forming a gentle caudal process, more developed in RV. Few small blunt spines bordering both, the anterior and postero-ventral margins. Dorsal and ventral margins nearly straight and slightly converging towards the posterior end. Antero-median concavity hidden by swelling of the valves. Surface ornamented by numerous blunt tubercles with different sizes and forms, mostly of them aligned in poorly defined rows. Anteriorly, two rows run parallel to the margin converging to the prominent eye tubercle. A quite short tuberculate or undivided rib, larger in RV, extends behind the eye tubercle. Posteriorly, two almost inconspicuous short rows extend subparallel to the margin. Two anterior and three to four posterior rows radiating from the weakly developed subcentral tubercle. The tuberculate ornamentation shows a relatively high degree of variability, either between the sexes or between valves of the same sex. Normal pore canals quite numerous, scattered, very likely provided with a less conspicuous sieve structure hidden in the depth of the pore. Internally, hinge holamphidont. RV hinge has a well-developed anterior tooth and a deep post-adjacent socket with a median smooth groove ending in a bilobate subrectangular posterior tooth. Adductor muscle pattern an oblique row of four scars, the middle two subdivided. Frontal scar split in two scars, the upper one more rounded. Inner lamella moderately well developed. Line of concrescence and inner margin slightly separated anteriorly, leaving a narrow vestibule. Radial pore canals straight, simple and numerous. Sexual dimorphism pronounced. Males more elongate and slightly narrower than the females and with a relatively weakly developed ornamentation.

Remarks. Bulbocythere calida gen. et sp. nov. is a peculiar hemicytherid. No similar species occurs in the Atlantic Ocean. Although we have analyzed more than one thousand samples, the larger female specimen (holotype) of this rare species is smaller (0.78 mm length) than we expected for a Hemicytheridae when compared with the adult male (0.85 mm length) of the same species. However, this is not so strange since other South Atlantic hemicytherid ostracods, such as Ruggiericythere Aiello, Coimbra & Barra, 2004 and some species of Caudites Coryell & Fields, 1973 (see Coimbra & Ornellas 1987) possess the same sex-size relationship.

Occurrence and distribution. Bulbocythere calida gen. et sp. nov. was recorded only in 16 shallow-shelf samples and in the Tamandaré Bay. On the Brazilian shelf, this rare species occurs scattered along the Eastern and Northeastern warm regions, mainly on biodetritic bottoms ( Fig. 1 , Tab. 1 ). However, in the Tamandaré Bay it is relatively more abundant, as shown in Table 1 of Coimbra et al. (1992, see Echinocythereis ? sp.).

Figures

FIGURE 1. Map of the study area and its regional zonation (modified from Muehe & Garcez 2005 and Luz & Coimbra 2015). Each dot represents a sample. Symbols: * Tamandaré Bay (Pernambuco State); + Sepetiba Bay (Rio de Janeiro State).

FIGURE 3. Bulbocythere calida gen. et sp. nov. 1 – 2 (MP-O- 1396, female, holotype). 1 — LV, 2 — LV, internal view. 3 – 6 (MP- O- 2584, female, paratype) 3 — LV, 4 — RV, 5 — LV, internal view, 6 — RV, internal view. 9 – 12 (MP-O- 2585, male, paratype) 9 — LV, 10 — RV, 11 — LV, internal view, 12 — RV, internal view. 7 – 8 (MP-O- 2584, female, paratype) 7 — LV, central muscle scars, 8 — RV, central muscle scars. 13 – 14 (MP-O- 2585, male, paratype) 13 — RV, central muscle scars, 14 — LV, central muscle scars. 15 (MP-O- 2586, female, paratype) carapace, dorsal view. 16 (MP-O- 2587, male, paratype) carapace, dorsal view. 17 (MP-O- 2588, male, paratype) anterior and posterior marginal pore-canals, not to scale. Scale bars: 1 – 6, 9 – 12, 15 – 16 (100 µm); 7 – 8 (20 µm); 13 – 14 (50 µm).

Tables

TABLE 1. Occurrence of Bulbocythere calida gen. nov. et sp. nov. in the study area. Abbreviations and symbols: TQS—terrigenous quartzose sand; BS—biodetritical sand; TMS—terrigenous muddy sand; TS + CG—terrigenous sand with carbonate sand; TCS—terrigenous coarse sand; * adult; + juvenile. TAB- 62 corresponds to the holotype.

Sample	Latitude (S)	Longitude (W)	Depth (m)	Sediments	N° of valves and carapace
TAB-62	08°45’	35°06’	7	BS	3v (1*)
L7-3759	08°03,5’	34°36’	50	BS	1c (+)
L7-3761	08°23’	34°41’	43	BS	2v, 3c (+)
L7-3763	08°32’	34°56’	25	BS	1c (+)
L7-3764	08°40’	35°00’	26	BS	3c (+)
L7-3767	09°19.5’	35°03’	44	BS	4c (+)
L7-3777	10°01’	35°54’	18	BS	2c (+)
L7-3778	10°12’	36°00’	22	BS	1v, 3c (+)
L7-3779	10°20’	36°04’	24	BS	1v, 3c (+)
L7-3786	11°17’	37°12’	22	TQS	2v, 2c (+)
L7-3787	11°25’	37°16’	15	TMS	1v (+)
L7-3788	11°38’	37°23’	18	TS+CG	1v, 9c (1*)
L7-3808	15°13’	38°54’	24	TS+CG	1v (+)
L7-3892	17°59’	38°01’	49	BS	1v (+)
L7-3906	18°26’	39°20’	24	TCS	2v (1*)
L7-3927	21°54’	40°11’	59	TMS	1c (+)
L7-3936	21°12.5’	40°35’	16	BS	1v, 1c (+)