Xestoleberis machadoae, Nathália C. da Luz & João C. Coimbra, 2014

Nathália C. da Luz & João C. Coimbra, 2014, New species of Xestoleberididae (Crustacea, Ostracoda) from Archipelago of São Pedro and São Paulo, Equatorial Atlantic, Iheringia, Série Zoologia 104 (4), pp. 470-477 : 474-476

Xestoleberis machadoae sp. nov.

(Figs 14-24)

Xestoleberis sp. 1 ANTONIETTO et al., 2012:40-41, Figs. 6:13-20; Tab. 9. Xestoleberis sp. 2 COIMBRA et. al., 2013:297, Fig. 62-66; Tab. 4.

Type material. Holotype, MP-O-2478, ♀, RV, length: 0.34 mm; height: 0.19 mm. Paratypes. MP-O-2466, ♂, RV, length: 0,28 mm; height: 0,13 mm ; MP-O-2479, ♀, LV, length: 0.33 mm; height: 0.16 mm ; MP-O-2480, ♀, carapace, width: 0.21 mm; length: 0.32 mm ; MP-O-2481, ♂, RV, length: 0.33 mm; height: 0.16 mm ; MP-O-2482, ♂, LV, length: 0.34 mm; height: 0.16 mm ; MP-O-2483, ♂, carapace, width: 0.19 mm; length: 0.33 mm .

Etymology. This species was named in honor of Cláudia Pinto Machado (Universidade de Caxias do Sul), a friend of the authors, in recognition of her contribution to the study of Recent Brazilian shallow water marine ostracodes, and for her tireless willingness to collect ostracodes in inhospitable Brazilian oceanic islands.

Type locality. Archipelago of São Pedro and São Paulo, Equatorial Atlantic .

Occurrence. See Table III.

Diagnosis. Carapace very small and relatively thin. Subrectangular elongate in lateral view; in dorsal view, oval in females and subpiriform in males. In ventral view, strongly flattened. Anterior margin obliquely rounded, projected ventrally, with an adjacent small sunken area. Posterior margin almost evenly rounded in RV, more narrowly rounded in LV. Surface predominantly smooth, with three different normal pore canals: sieve-type, simpletype and lip-type. In SEM, there are one very delicate anteroventral submarginal rib and two minor ribs behind it.

Description. A very small and relatively thinshelled species of Xestoleberis . Subrectangular elongate in lateral view. In dorsal view, strongly inflated and ovate. In ventral view, strongly flattened. LV overlapping RV mainly anteriorly and posterodorsally. Maximum length almost ventrally. Maximum height medially. Maximum width near the middle. Anterior margin obliquely rounded, projected ventrally, with a depressed region adjacent to it forming a well-defined small sunken area. Posterior margin almost evenly rounded in RV, more narrowly rounded in LV. Dorsal margin moderately convex. Ventral margin almost straight, hidden by a lateral inflation more developed in LV. Surface predominantly smooth, with three patterns of normal pore canals (sensu SATO & KAMIYA, 2007): sieve-type, simpletype and lip-type. In SEM, there are one very delicate anteroventral submarginal rib and two minor ribs behind it. Xestoleberis -spot small and almost invisible. A large vestibulum is present anteriorly. Selvage subperipheral in both valves, bending outwards in the oral region. Marginal pore canals not numerous, simple and straight. Hinge hemimerodont, with delicately crenulate terminal teeth in RV; median element smooth. Central muscle scars constituted by four adductors vertically aligned and a frontal U-shaped. Mandibular scars not visible. Sexual dimorphism present. Males with a more arched dorsal margin and less developed lateral inflation in LV. In dorsal view, subpiriform. Maximum width posteriorly.

Remarks. Xestoleberis machadoae sp. nov. has less than 0.4 mm in length, exhibits elongate and dorsally gently convex valves in lateral view, hinge hemimerodont with slightly crenulate terminal teeth in RV and smooth hinge-bar in LV, and Xestoleberis -spot poor-developed, features typical of the Xestoleberis arcturi Triebel group of BONADUCE & DANIELOPOL (1988). Conversely, this new species does not fit well in any group proposed by SATO & KAMIYA (2007) for Japanese species.