Genus Castianeira Keyserling

Castianeira Keyserling, 1879 . Verh. Zool. Bot. Ges. Wien.: 335.

Thargalia Karsch, 1880. Zeit. f.d. Ges. Natur. 53: 374.

Tylophora Simon, 1887. Ann. Soc. Ent. Fr.: 377.

Geotrochu Emerton, 1890. Trans. Conn. Acad. Arts Sci. 8: 4.

Castiuneira Comstock, 1940. The Spider Book. New York: 592.

Medium-sized (4-8 mm long) clubionids with elongated ant-like bodies and moderately long and thin legs. The members of the genus are easily recognized by the heavily sclerotized, sometimes shiny carapace and abdomen; carapace elongate ovoid, bulging and highest along fovea dark brown to reddish black, darker in eye area; small eyes uniform in size, in two transverse rows with AE recurved, AME closer to laterals than to each other, PE distinctly procurved and longer than AE; chelicerae moderately long, robust, and hirsute, with two promarginal and two (sometimes three) retromarginal teeth; outer laterals of maxillae convex and not constricted; legs long and slender, usually orange to dark brown or black, possessing short dense claw tufts and thin scopulae; trochanter IV with prominent apicoventral notch; femur I with two or three dorsal spines, one or two prolaterals, metatarsus I with four ventral spines in two pairs. Abdomen elongated, ovoid to slender, with transverse bands of white scale-like setae and large shiny dorsal epigastric and ventral scuta (reduced in females), lacks cluster of long erect setae at anterior end; femur and patella of male palpus without apophysis; tibia with strong retrolateroventral ridge bearing one or more small teeth; cymbium basally rounded, long and slender distally; tegulum like cymbium but enclosing two loops of seminal duct within base; embolus long and slender, straight, spirally twisted apically, emanating directly from elongated tip; epigynum with rounded convex hairy plate, copulatory openings small, round, elliptical and slit-like, well separated, distinct, and often linked by shallow grooves; spermathecae longer than wide, touching midline, rugose, and commonly with slender posterior part quite close to the anterior of genital groove.

These spiders are common in leaf litter in shady environments, some associated with ants.