Xestoleberis virilis, 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 : 191-193

Xestoleberis virilis sp. nov.

Fig. 6 : 1–11

Type series. Holotype: MP-O-1814, adult male, carapace width 0.24 mm; RV length 0.47 mm, height 0.30 mm; LV length 0.48 mm, height 0.31 mm. Paratypes: one adult male (MP-O-1815) and one adult female (MP-O-1816).

Type locality. REMAC /Leg 7—Sample 3935 (21°02’S / 40°36’W); depth: 17 m; sediment: carbonate sand, gravel and some red algae.

Etymology. Latin origin, virilis = male, with reference to the greater number of male specimens.

Material. 15 adults.

Dimensions. See table 5.

Diagnosis. A medium-sized species of Xestoleberis . Carapace sub-rectangular in lateral view. LV overlapping RV along almost entire margin, except antero- and posteroventrally. Posterior margin sloping obliquely posteroventrally. Surface smooth with simple pore canals. Xestoleberis -spot conspicuous, outlined and divided into two parts. Hinge antimerodont with median element quite long. Four adductor muscle scars with dorsal one almost divided in half and ventral scar sub-ovate. Frontal muscle scar U-shaped.

Description. A medium-sized and thick-shelled species of Xestoleberis . Sub-rectangular in lateral view. Subovate in dorsal view. Ventral surface flattened. LV overlapping RV along almost entire margin, except antero- and posteroventrally. Maximum length just below mid-height. Maximum height near mid-length. Maximum width medianly. Anterior margin asymmetrically rounded. Posterior margin sloping obliquely posteroventrally. Dorsal margin arched. Ventral margin slightly sinuous. Surface typically smooth with simple-type pore canals (sensu Sato & Kamiya 2007). Eye-spot inconspicuous. Xestoleberis -spot conspicuous, outlined and divided into two parts. Line of concrescence separated from inner lamella forming a relatively large vestibulum anteriorly and a narrow one posteroventrally. Selvage peripheral anteriorly and posteriorly, sub-peripheral ventrally. Marginal pore canals numerous, simple and straight. Hinge antimerodont with terminal teeth in RV; median element crenulate and quite long. Adductors muscle scars a row of four scars, the dorsal almost divided in half, the dorsal-median and ventralmedian sub-elliptical, the ventral somewhat rounded and sub-cordate; frontal muscle scar U-shaped. Sexual dimorphism present: female conspicuously larger than male and more flattened ventrally, with posterior end subtruncated in RV and a little more rounded in LV.

Remarks. This relatively rare species was described mainly based on the carapace of the male, of which many more specimens were found. The male and female of Xestoleberis virilis sp. nov. have important differences in outline, which can also be observed in other species of this genus, for example X. ramosa Müller, 1908 , from South Africa.

Occurrence and distribution. Xestoleberis virilis sp. nov. was recorded in the Northeastern and Eastern regions of the Brazilian continental shelf ( Fig. 2 ; Tab. 1) in a range depth of 16 to 37 m.

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 6. 1 – 11. Xestoleberis virilis sp. nov. 1. Female, RV (MP-O- 1816). 2. Female, LV (MP-O- 1816). 3. Male, dorsal view (MP-O- 1814, holotype). 4. Male, Carapace, RV (MP-O- 1814, holotype). 5. Male, LV (MP-O- 1815). 6. Male, ventral view (MP-O- 1814, holotype). 7. Xestoleberis - spot (MP-O- 1816). 8. Simple-type normal pore canal (MP-O- 1816). 9. Central muscle scars, LV (MP-O- 1815). 10. Hinge (MP-O- 1816). 11. Schematic drawing of some internal features. 12 – 14. Xestoleberis sp. 12. Carapace, RV (MP-O- 1698). 13. Carapace, LV (MP-O- 1698). 14. Carapace, dorsal view (MP-O- 1698).