Bimichaeliini Womersley, 1944

Uusitalo, Matti, 2025, A review of the family Alycidae (Acari, Acariformes) from North America, Zootaxa 5602 (1), pp. 1-92 : 33-34

Tribe Bimichaeliini Womersley, 1944

Type genus: Bimichaelia Thor, 1902 .

Differential diagnosis. The tribe differs from its monotypic sister group, the tribe Proteromichaeliini , by having the following features: either glabrous ridges ( Fig. 51B), or ridges with middle-sized lamellae in clumps ( Fig. 51C) or large lamellae in separate polygons ( Fig. 51A, D, E) on soft integument (compared to the primary pattern formed by both clumps and rosettes of large lamellae [ Uusitalo et al. 2020: fig. 134A, B]); the absence of eyes ( Figs. 52B, F, J, 53B, F, J) and cheliceral setae ( Fig. 53H); and femora IV not divided ( Figs. 28D, 35C). Otherwise, they share the typical bimichaeliine character states, such as presence of clavate sensilla sci, stylet-like chelicerae, and an apical palpal solenidion in contact with TP-type eupathidia.

Genus Glabromichaelia gen. nov.

Type species: Glabromichaelia vazquezrojasi sp. nov.

Differential diagnosis. The genus differs from other genera of Bimichaeliini and Proteromichaeliini by having parallel, glabrous ridges all along the dorsal and ventral integument (i.e. there is no stellate or cellular pattern of ridges), no primary pattern (i.e. large lamellae on ridges or in clumps), and no secondary pattern with smaller lamellae or granulae in between large lamellae (i.e. integument’s reticulation, lamellae and granulae are absent) ( Fig. 19B–D). Other diagnostic features are as follows: the unique presence of large (or baculiform) solenidia on tarsi, tibiae, genua and femora I, II, III and IV, respectively—2200, 1111, 0100, and 0100—as presented as the solenidial pattern in Uusitalo (2010: 25). In other respects, the species is similar to the rest of the bimichaeliines.

Description. Glabrous larger and finer ridges running parallel and covering dorsal and ventral sides ( Fig. 19B–D); invaginate areas with softest skin, such as basis of chelicera, joints of leg segments and genital orifice are with rows of small, transverse laminae ( Figs. 20F, 21G); elongated dorsal and ventral setae with 20–30 cilia each ( Fig. 19B–D); naso small with rounded tip and parallel sides, some accessory setae on prodorsal soft integument and in -area, anterior pair of sensilla ve densely ciliated by cilia of various lengths, longest being distal ( Figs. 17A, 20A, B); chelicerae straight with some teeth but without setae ( Figs. 20C, 21C); palps short and stout, palpal solenidion medially constricted, in contact with two eupathidia and with a basal tubercle ( Fig. 21A, B); two baculiform but slim solenidia on tarsi I and II, one baculiform solenidion on each of tibiae 1–IV (instead of 2), one baculiform solenidion on genu II and femur II ( Figs. 18C, D, 20F, 21D, E, 22A–D); strong neotrichy already on protonymph ( Fig. 20C).

Remarks. The genera in the tribes Bimichaeliini and Proteromichaeliini are based on the form of the integument, which assumes that the form of the integument is synapomorphic for each genus. The genus Bimichaelia can be characterised by its granular secondary pattern, Laminamichaelia by the presence of transversely packed lamellae of the secondary pattern, the granulae/lamellae are absent in Glabromichaelia , and Proteromichaelia has clumps of large lamellae inside roundish cells of large lamellae (=primary pattern) plus a secondary pattern by fine ridges. The difference between the patterns of baculiform solenidia of Glabromichaelia (given above) and Proteromichaelia is only one solenidion ( Uusitalo 2010: 25, state 7 and appendix 3). The parallel ridges on the integument of the new genus Glabromichaelia (tribe Bimichaeliini ) are similar to the ridges in the tribes Alycini and Petralycini and support the idea of monophyly in the family Alycidae (see Uusitalo 2010: 11). That the glabrousness of ridges is due to the loss of laminae/granulae remains an open question.

Etymology. The first part of the generic name refers to the glabrous dorsal and ventral ridges of integument. This structure of integument is probably a plesiomorphic character state without primary and secondary pattern, i.e. without granulae and/or lamellae, which are common to all the other members of various species groups of the tribes Bimichaeliini and Proteromichaeliini , but also Alycini and Petralycini ; and “Michael”, referring to the British acarologist Albert Davidson Michael (1836–1927).