Auricythere sublitoralis, de Morais & Coimbra, 2014

de Morais, Anderson L. M. & Coimbra, João C., 2014, On a new genus and species of Hemicytheridae (Ostracoda, Crustacea) from the southern Brazilian coast, Iheringia, Série Zoologia (Série Zoologia) 104 (3), pp. 367-372 : 369

Auricythere sublitoralis sp. nov.

( Figs 2-21 )

Mutilus sp. 1 DIAS- BRITO et al., 1988:480, Pl. 2: 45.

Auradilus sp. MACHADO et al., 2005:240, Pl. 2: 16.

Type material. Holotype, MP-O-2467, carapace, ♀, length: 0.56 mm; height: 0.33 mm . Paratypes. MP-O-2468, carapace, ♂, length: 0.54 mm; height: 0.30 mm ; MP-O-2469, A-1 carapace, ♀, length: 0.52 mm; height: 0.30 mm; width: 0.24 mm ; MP-O-2470, carapace, ♂, length: 0.53 mm; height: 0.30 mm; width: 0.24 mm ; MPO-2471, A-1 carapace, ♀, length: 0.53 mm; height: 0.31 mm ; MP-O-2472, carapace, ♂, length: 0.53 mm; height: 0.30 mm ; MP-O-2473, A-1 carapace, ♂, length: 0.52 mm; height: 0.28 mm .

Etymology. From Latin origin, sublitoralis = situated near the seashore, because of its first record being restricted to very shallow coastal waters.

Type locality. Holotype: sample M0943N, Porto Belo town, Estaleiro beach, 27°07’S / 48°31’W, on algae . Paratypes: MP-O-2468, sample M0941N; MP-O-2469 and MP-O-2473, sample M0961N ; MP-O-2470, sample M0942N ; MP-O-2471N, sample M0947N ; MP-O-2472, sample M0943N . For more details, see Tab. I .

Occurrence. See Tab. I .

Description. Carapace small, thick-shelled, somewhat ear-shaped mainly in LV lateral view. Maximum height at anterior cardinal angle. In dorsal view, compressed and with subparallel sides. Maximum width in the posterior region, poorly defined. LV conspicuously larger than RV, the margin of which overlaps it in dorsal region and immediately above the caudal process. In lateral view, anterior margin rounded, gently concave immediately in front of the anterior cardinal angle in RV. Posterior margin with discrete caudal process, more developed in RV. Dorsal margin slightly convex, sloping posteriorly, obscured by the ornamentation in LV. Ventral margin sinuous, with evident oral concavity more developed in RV. Surface ornamented by numerous ribs intercalated by depressed and reticulate areas. Ribs predominantly low, thick and somewhat truncated. Posterior region with a vertical rib subparallel to the correspondent margin, bifurcated at the top and the bottom: at the top, a short branch runs forwards and upwards while the second one reaches the posterior cardinal angle; at the base, a longer and sinuous branch runs forwards and downwards while the shorter and more rectilinear branch runs downward, turning forward before reaching the ventral margin. Eye tubercle conspicuous, crossed by a strong rib, more robust in its anterior branch that ends at about half height.Ventro-lateral rib delicate, not overlapping the corresponding margin. Six to seven well-developed reticulae adjacent to the anterior margin. Normal pore-canals sieve-type, scattered on the costae and muri. Internal view. Accommodation groove well developed in LV. Hinge holamphidont. LV posterior socket with a conspicuous aurila-tooth and an auxiliary small anti-slip tooth at its posterior end (sensu JELLINEK, 1995). Large duplicature with a conspicuous selvage nearest to the external margin anteriorly. Anterior vestibule narrow and elongated. Radial pore-canals numerous, simple and straight, more abundant anteriorly. Central muscle scars with three frontal and four adductors (1+2+1+1), as follows: dorsal rounded, dorsomedian subdivided, dorsoventral sinuous and elongated, and ventral subelliptical. The frontal ones sometimes not well defined; upper and middle scars frequently somewhat anastomosed. Sexual dimorphism not prominent. Males with a little more developed caudal process and a less arched dorsal margin.

Remarks. DIAS- BRITO et al. (1988) and MACHADO et al. (2005) identified erroneously specimens of Auricythere sublitoralis sp. nov. as Mutilus sp. 1 and Auradilus sp. , respectively. However, BONADUCE et al. (1987) considered Mutilus Neviani, 1928 as an extinct genus whose occurrences are restricted to the Mediterranean Neogene and Quaternary. In respect to the ornamentation, Mutilus bears a typical butterfly-shape in the central area of the valves, present in all its species. Besides, this aurilinid fossil genus possesses a well-defined frame-rib, not developed in A. sublitoralis sp. nov. On the other hand, Auradilus features outline, ornamentation and central muscle scarsvery different of the new ostracode herein described, as already discussed above.

Figures

Figs 2-16. Auricythere sublitoralis gen. nov., sp. nov.: 2, MP-O-2467, LV, ♀; 3, MP-O-2467, RV, ♀; 4, MP-O-2467, LV, ♀, posterior marginal porecanals, not in scale; 5, MP-O-2467, LV, ♀, anterior marginal pore-canals, not in scale; 6, MP-O-2467, RV, ♀, anterior marginal pore-canals, not in scale; 7, MP-O-2467, RV, ♀, posterior pore-canals, not in scale; 8, MP-O-2469, A-1 c, ♀, dorsal view; 9, MP-O-2468, LV, ♂; 10, MP-O-2468, RV, ♂; 11, MP-O-2470, c, ♂, dorsal view; 12, MP-O-2471, LV, ♀, internal view; 13, MP-O-2471,A-1 RV, ♀, internal view; 14, MP-O-2472, LV, ♂, internal view; 15, MP-O-2472, RV, ♂, internal view; 16, MP-O-2473, A-1 c, ♂, ventral view. The scale of all specimens = 100 µm, if no other indication.

Figs 17-21. Auricythere sublitoralis gen. nov., sp. nov.: 17, MP-O-2472, LV, ♂, central muscle scars; 18, MP-O-2472, RV, ♂, central muscle scars; 19, MP-O-2471, LV, ♀, central muscle scars; 20, MP-O-2468, RV, ♂, normal pore sieve-type; 21, MP-O-2468, RV, ♂, normal pore sieve-type. Scale bars: 17-19 = 10 µm; 20, 21 = 1 µm.