Acheroxenylla Ellis, 1976 new modified diagnosis

Palacios-Vargas, Jose G., 2020, Acheroxenylla (Collembola, Hypogastruridae), first record from the Americas with description of a new species from a Peruvian cave, Subterranean Biology 34, pp. 109-119 : 109

Acheroxenylla Ellis, 1976 new modified diagnosis

Notes.

Small Hypogastruridae (from 0.5 to 1.3 mm). Setae not differentiated in macrosetae, only with smooth or slightly barbulate mesosetae and longer sensory setae. They are usually white, with dark or black color only under each eye, with possible bluish gray pigmentation all over the body. Antennae cylindrical about the same length as the head, with a simple or trilobed retractile papilla; Ant IV with a dorso-external microsensillum, a subapical sensorial organ and 4 cylindrical or oval sensilla: 3 external and one internal. Ant. III organ with 2 microsensilla hidden by or not by a tegumentary fold and framed by 2 longer guard sensilla. Ocelli 2 + 2 (sometimes 1 + 1). Postantennal organ always lacking. Head chaetotaxy with setae a0 and d0; five pairs of dorsal cephalic setae; and two or three subdorsal pairs. Claws without teeth and empodium. Th I with 3 + 3 setae; Th II-III with 4 + 4 setae on row a, 3 + 3 on m row and 4 + 4 on row p. Or a: 3 + 3 and 2 + 2; m: 3 + 3 (m2 and m3 absent) and 1 + 1 lateral; p: 4 + 4 or 5 + 5; two pairs of ss at position m6 and p4. Without lateral microsensillum on Th II. Abd I-III with 2 rows of setae (a and p): 5 + 5 or 6 + 6; one pair of ss at p5; Abd IV with 3 rows of setae (a: 3 + 3 or 4 + 4; m: 2 + 2 (with or without m1 or m4); p: 4 + 4 or 5 + 5; one pair of ss at position p5). Abd V with 2 rows (a and p: 2 + 2 or 3 + 3) one pair of ss at position p3. Each tibiotarsus with 2 or 1 tenent hairs. Ventral tube with 4 + 4 setae. Retinaculum either with 2 or 3 teeth on each ramus or complete absent. Furcula present, reduced or absent. Manubrium, when present, with 2 or 3 pairs of setae, dens if present short or long with maximum 2 setae. Mucro absent except one case. Always with 2 very small anal spines on papillae of the same size.

Type species.

Acheroxenylla cretensis Ellis, 1976