Costal field: Orthoptera; that region of the tegmina adjacent to the anterior margin or costa: = anterior field.
Costal fold: in the males of some Hesperidae, a membranous flap that may be opened to expose the androconia.
Costal margin: the anterior margin of a wing whether it is really costate or not.
Costal membrane: Hymenoptera; the surface of wing in front of costal vein.
Costal vein: Lepidoptera; runs close to and parallel with the costal margin, extending from base to the margin before the apex; always simple and often absent in the secondaries; is vein 12 of the numerical series on primaries; vein 8 on secondaries: = subcosta (Comst.).
Costate: ribbed; marked with elevated thickened lines.
Costula: Hymenoptera; a small ridge separating the externo-median meta-thoracic area into two parts.
Costulatus: less prominently ribbed than costate.
Cotyla: the articular pan; the cup or socket of a ball and socket joint.
Cotypes: are all the specimens before the describer when a species is named, no single one being selected as the type: the type in such case equals the sum of the cotypes: see paratype.