costa

costa (noun; plural cortices; adjective cortical; Latin cortex, bark): 1. Any rib-like structure.

2. (Arthropoda: Crustacea) Any thickened portion of the peniferum of ostracods.

3. (Arthropoda: Insecta) a. The longitudinal wing vein of certain insects, forming the anterior margin of the wing. b. A dorsal, marginal part of the valva of male Lepidoptera, bearing a variety of structures and processes.

4. (Brachiopoda) a. Radial ridge on the exterior surface of the shell, originating at the margin of the protegulal node. b. Any coarse rib.

5. (Bryozoa: Gymnolaemata) One of commonly two spines fused medially and intermittently laterally, that form the costal shield of cribrimorph cheilostomate zooids.

6. (Cnidaria) Prolongations of the septa of certain corals, that connect to the surface layer.

7. (Ctenophora) The row of swimming plates (ctenes) that occupy adradial positions.

8. (Mollusca) The rounded ridge on the surface of a mollusk shell, greater than a chord.