Orechina catalinae, Salas & Vaccari, 2012

Salas, María José & Vaccari, N. Emilio, 2012, New insights into the early diversification of the Ostracoda: Tremadocian ostracods from the Cordillera Oriental, Argentina, Acta Palaeontologica Polonica 57 (1), pp. 175-190 : 184-185

Orechina catalinae sp. nov.

Fig. 8D, F–H .

Etymology: For one of my (MJS) twins Catalina.

Holotype: CEGH−UNC 24037 , external mould of left valve ( Fig. 8G ).

Type locality: Quebrada de Humahuaca area, northwest Argentina.

Type horizon: V1f sample, lower levels of the Humacha Member, Santa Rosita Formation, Middle Tremadocian.

Diagnosis.—Subcircular and amplete in outline. Well defined, short, and V−shaped adductorial sulcus. Lateral surface flat, without the bend between the lateral and marginal surface.

Description.—Sub−elliptic to circular outline, amplete. Average L:H 1.55. Maximum length at the mid−height of the valves. Dorsal margin straight and shorter than the maximum length. Lateral and ventral margin evenly rounded. Cardinal angles obtuse, the anterior is smaller and better defined than the posterior angle. The valves are unisulcate. The adductorial sulcus (S2) is present in the anterodorsal half of the valve. It is well developed, short, does not reach the ventral half of the valve, is wide dorsally and V−shaped. The lateral surface is nearly flat, and reticulate.

Material.— More than 20 specimens from internal to external moulds, including the figured material CEGH−UNC 24017 , 24027–28 , 24037 . Specimens we have examined range from 0.68 mm to 1.20 mm in length .

Discussion.— Orechina catalinae sp. nov. is similar to Orechina violetae sp. nov. from the Coquena Formation of the Chalala section but differs in the lack of a muscle spot, the more rounded cells of the reticulation and the flatter lateral surface. With respect to the others species included in the genus, Orechina catalinae sp. nov. is bigger (L reaches 1.20 mm), the reticulation takes up nearly all the valve surface, and the dorsal ridge, the bend between the lateral and marginal surfaces, and the muscle spot are absent.

Stratigraphic and geographic distribution.—Known only from the type locality.

Figures

Fig. 8. Late Tremadocian binodicopids ostracods from the Northwest Basin of Argentina. A–C, E. Orechina violetae sp. nov. Coquena Formation in Chalala section, Purmamarca area. A. Holotype CEGH−UNC 24029, right valve in lateral view. B. CEGH−UNC 24030, left valve in lateral view. C. CEGH−UNC 24031, right valve, lateral (C1) and ventral (C2) views. E. CEGH−UNC 24036, internal mould of right valve, lateral view. D, F–H. Orechina catalinae sp. nov. Humacha Member of the Santa Rosita Formation, lower part of the Humacha section. D. CEGH−UNC 24017, left valve in lateral view. F. CEGH−UNC 24027, left valve in lateral view. G. Holotype CEGH−UNC 24037, left valve in lateral view. H. CEGH−UNC 24028, right valve in lateral view. Scale bars 100 µm.