Xestoleberis inesae, Luz, Nathália Carvalho Da & Coimbra, João Carlos, 2015

Luz, Nathália Carvalho Da & Coimbra, João Carlos, 2015, The genus Xestoleberis (Ostracoda: Xestoleberididae) in the Northern, Northeastern and Eastern regions of the Brazilian continental shelf, Zootaxa 3974 (2), pp. 177-195 : 185-187

Xestoleberis inesae sp. nov.

Fig. 3 : 1–12

1999 Xestoleberis sp. 1 Coimbra et al., pl. 3, fig. 7; tab. 1.

2008 Xestoleberis sp. 1 Machado, p. 127, pl. 5, figs. 18–19, tab. 6, 8.

Type series. Holotype: MP-O-1608, adult female, carapace width 0.38 mm; RV length 0.54 mm, height 0.36 mm; LV length 0.57 mm, height 0.36 mm. Paratypes: two adult males (MP-O-1609 and MP-O-1610), one adult female (MP-O-1611) and one juvenile (MP-O-1612).

Type locality. REMAC /Leg 7—Sample 3820 (16°24.5’S / 38°35’W); depth: 51 m; sediment: carbonate gravel and sand.

Etymology. In honor of Maria Inês Feijó Ramos, in recognition of her contribution to the knowledge of Recent and fossil ostracods from Brazil.

Material. 245 adults and 270 juveniles.

Dimensions. See table 2.

Diagnosis. A large-sized species of Xestoleberis . Carapace sub-ovate in lateral view with ventral margin almost straight and posterior margin truncated ventrally. LV overlapping RV along almost all the entire margin. Surface smooth with lip-type pore canals and not well-defined large opaque patches. Xestoleberis -spot conspicuous, long and outlined. Hinge antimerodont with robust terminal teeth in RV. Adductors muscle scars with an oblique V-shaped spot at the top. Frontal scar U-shaped.

Description. A large and thick-shelled species of Xestoleberis . Sub-ovate in lateral and dorsal views. Ventral surface flattened. LV overlapping RV along almost all the entire margin, except anteroventrally, posteroventrally and somewhat at the anterior cardinal angle. Maximum length in the lower third of the height. Maximum height medianly. Maximum width posteriorly. Anterior margin obliquely rounded and protruding. RV posterior margin rounded dorsally and truncated ventrally. LV posterior margin evenly rounded. Dorsal margin convex. Ventral margin almost straight. Surface typically smooth, with lip-type pore canals (sensu Sato & Kamiya 2007) and not well-defined large opaque patches. Eye-spot inconspicuous. Xestoleberis -spot conspicuous, long and outlined. Inner lamella separated from line of concrescence anteriorly and posteriorly, forming two small vestibules. Selvage peripheral in both valves, except mid-ventrally. Straight and spaced marginal pore canals. Hinge antimerodont, with numerous very well-developed teeth in RV and sockets in LV. Median element crenulate. Central muscle scars consisting of four adductor scars vertically aligned: from the base to the top, the two first adductors scars are subelliptical, the third one somewhat rounded and the last one oblique and V-shaped; frontal scar U-shaped and with two mandibular scars. Sexual dimorphism present: male less flattened ventrally than female, with dorsal margin more inclined. In dorsal view, female more inflated than male.

Remarks. Xestoleberis inesae sp. nov. has a carapace outline similar to Xestoleberis margaritea (Brady, 1966) , first described from Recent samples of Europe and identified by Bold (1963) in the Miocene and Pleistocene of Trinidad. The species differ from each other by the presence of papillae in the lateral surface of X. margaritea not observed in the quite smooth species herein described; the posterior margin is more rounded in X. margaritea . Xestoleberis inesae sp. nov. is also similar to the female of X. virilis sp. nov., differing by the more protruding anterior margin and more convex dorsal margin in the former. Besides, the Xestoleberis -spot of X. inesae sp. nov. is larger and not subdivided as in X. virilis .

Occurrence and distribution. Xestoleberis inesae sp. nov. occurs along the Northern, Northeastern and Eastern regions of the Brazilian continental shelf ( Fig. 2 ; Tab. 1), in a depth range of 11 to 223 m. This is the most abundant Xestoleberis species of this genus between Orange Cape and the town of Cabo Frio.

Figures

FIGURE 2. Distribution of Xestoleberis species in Brazilian continental shelf. The hatched area corresponds to the Transitional Zone of Coimbra et al. (1995). Each dot represents one sample.

FIGURE 3. 1 – 12. Xestoleberis inesae sp. nov. 1. Female, Carapace, RV (MP-O- 1608, holotype). 2. Female, Carapace, LV (MP-O- 1608, holotype). 3. Female, dorsal view (MP-O- 1608, holotype). 4. Male, RV (MP-O- 1609). 5. Male, LV (MP-O- 1609). 6. Male, dorsal view (MP-O- 1610). 7. Hinge (MP-O- 1611). 8. Central and mandibular muscle scars, RV (MP-O- 1612). 9. Female, ventral view (MP-O- 1608, holotype). 10. Lip-type normal pore canal (MP-O- 1608, holotype). 11. Schematic drawing of some RV internal features. 12. Xestoleberis - spot (MP-O- 1607). 13 – 14. Xestoleberis umbonata Whatley et al. 1998. 13. Male, RV (MP-O- 1606). 14. Male, LV (MP-O- 1607).