Adisianus Bretfeld, 2003

Rodrigues, Iandra Vitória Bezerra, Medeiros, Gleyce Da Silva, Nunes, Rudy Camilo & Bellini, Bruno Cavalcante, 2025, The rare Adisianus Bretfeld (Collembola, Bourletiellidae): a new species from Northeastern Brazil and an identification key to the genus, Zootaxa 5632 (3), pp. 580-594 : 583

Genus Adisianus Bretfeld, 2003

Diagnosis of the genus. Specimens pigmented. Antennae shorter than body, Ant IV subsegmented. Eyes 8+8, head roundish, mouthparts normal, not elongated, maxilla capitulum spherical. Large abdomen elongated, parafurcal area (furca basis) with one neosminthuroid chaeta on each side. Coxae II and III with a short spiny sensillum in a large alveolus, each. Tibiotarsi I–III with 3, 3, 2 slightly capitate chaetae and one oval organ, respectively, without toothed or obliquely truncated chaetae. Unguiculi smaller than ungues and pointed, unguicular lamella only developed at the base. Formula of ventral (anterior) dens chaetotaxy as 4, 0–1…1 from apex to basis (revised and updated from Bretfeld, 2002).

Type species: Adisianus maculatus ( Bretfeld, 2002)

Remarks. We simplified the original diagnosis of the genus, removing the presence of rough and blunt spine-like chaetae on head, antennae and abdomen, since Adisianus maassius ( Palacios-Vargas & Gonzalez, 1995) apparently lacks spine-like chaetae on the antennae, while on head and trunk they are pointed and almost smooth ( Bretfeld 2002). In fact, the frontal head spine-like chaetae of this species are remarkably different from other Adisianus taxa, including the new species herein described (see Palacios-Vargas & Gonzalez 1995, p. 291, fig. 29; Bretfeld 2002, pp. 128 and 130, figs 3–4, 19). Even so, other features listed in our diagnosis are shared between A. maassius and its congeners. Such shared morphology, with the exception of the presence or absence of blunt spine-like chaetae, was the main reason why Bretfeld transferred A. maassius from Deuterosminthurus Börner, 1901 to his new erected genus ( Bretfeld 2002), which corroborates our simplified updated diagnosis.

We also removed from the original diagnosis: the presence of a sexually dimorphic chaeta on the Ant III of males, since the morphology of A. maassius males was never studied before ( Palacios-Vargas & Gonzalez 1995; Bretfeld 2002); the presence of a modified Ja chaeta on distal tibiotarsus, which was apparently not observed in A. maassius ( Bretfeld 2002) ; and the Ant IV sensilla formula, which we could not clearly identify in our specimens. It is worth noting that sexually dimorphic structures described for A. maculatus ( Bretfeld, 2002) and A. fuscus ( Bretfeld, 2002) should be interpreted with caution, as the author could not analyze adult females of both species (see Bretfeld 2002, pp. 111, 113).