Microceratina Swanson, 1980

Danielopol, Dan L., Cabral, M. Cristina, Horne, David J., Namiotko, Tadeusz & Lord, Alan R., 2023, Reconciling diagnostic traits in living and fossil taxa: The taxonomy and evolution of the genus Microceratina (Crustacea, Ostracoda, Cytheruridae), Zootaxa 5244 (4), pp. 301-340 : 330

Microceratina Swanson, 1980 —new emended diagnosis

A genus of the Eucytherurinae with carapace in external lateral view of quasi-rectangular shape and broadly arched anterior and posterior valve margins; posterior with smaller rounded margin as compared to anterior one. Caudal process absent. Dorsal margin in lateral view straight or slightly convex in the middle, the convexity varies from horizontal to a slightly antero-posterior inclination in relation to the ventral margin. Carapace generally small: L <0.55 mm, H/L% generally <50%, H located either in the anterior or middle L. Valves reticulum comprises an extended network of ridges (muri) displaying a macro-reticular pattern with cells of diverse polygonal shapes and sizes. The sola of the reticular cells house shallow fossae surrounded by small 2 nd order muri with Loophole pores (LStPC) open on the bottom. The LStPC display an aggregation of thin tubules of <0.2–0.3 µm diameter that penetrate the calcified outer lamella and end within a larger space of the calcified wall, generally <1 µm. Simple NPC generally of conuli type (A”- type), located on or adjacent to the 1 st order muri of the reticula cells, or more rarely on the sola of the reticula. Internally the position of the selvage’s apex on the anterior side of the RV lays proximally to the outer margin. Marginal pore canals simple, they open on a thin ridge (the external lip) of the AMZ. Adductor muscle scar imprints a series of four horizontally elongate scars arranged in a vertical row within a shallow depression, with anteriorly either one U-shaped imprint or two small frontal scars. Hinge of merodont or entomodont type. Appendages—antennular distal seta fused at the base with an aesthetasc. Antenna with the 2 nd and 3 rd endopodial podomeres fused. The 4 th endopodial podomere of the antenna with two strong claws associated with, on the outer side, a thick seta resembling an aesthetasc. The distal podomere of the maxillular palp with both distal and subapical setae; maxillular branchial plate with two reflexed setae. Chaetotaxy formulae of protopodites of walking legs (L5–L7): L5—1:1:2; L6 — 1:1:2; L7 — 0:1:1.