Allonothrus, van der Hammen, 1953

Norton, Roy A. & Ermilov, Sergey G., 2024, Evaluation of morphological traits in Trhypochthoniidae with focus on Allonothrus, and morphology-molecule conflict in classification and phylogeny of Nothrina (Acari: Oribatida), Zootaxa 5556 (1), pp. 144-199 : 166

Leg setation in Allonothrus

Our knowledge of setal ontogeny is based on an unpublished study of Allonothrus giganticus from Kerala, India. This name is a senior subjective synonym of Allonothrus pararusseolus Subías & Sarkar, 1982 from Tripura, India (new synonymy). The latter authors seem to have been unaware of Haq’s (1978) publication. One of us (R.A.N.) studied specimens from the type locality, identified by M. Haq, and had A. giganticus in culture. While the verbal description of A. giganticus is sufficiently detailed, the illustrations are somewhat misleading. As examples: seta le was drawn as hardly exceeding the rostral margin (his Fig. 5 ), but actually it far overhangs; the notogaster seems illustrated with 16 pairs of setae, but h 3 is duplicated in dorsal and ventral views; genital setae appear to be uniform (his Fig. 6 ) but the posterior two pairs are simple, not barbed like the others. These and other features were more accurately illustrated by Subías & Sarkar (1982). Neither paper mentioned a posterior notogastral cavity in the pygidial region, but an indistinct one is present in studied specimens.

Appendix 1 presents the ontogeny of setiform organs of A. giganticus . Previously, a small part of this information was published by Wang & Norton (1988). Notable traits include; the presence of four larval setae (including cʺ) on tibia I, with a final complement of six; the absence of cʺ from larval tibia II, with a final complement of five; the absence of several fundamental tarsal setae, including primilateral setae (pl) from tarsus I, primiventral setae (pv) from tarsi II and III, fastigial seta ftʹ from tarsus III, and antelateral (a) setae from tarsus IV. Regarding accessory setae, the iteral pair (it) are absent and the adult forms proximal setae on each tarsus: pair (l A) on tarsus I; l A ʹ on II, and pair (v A) on II–IV.

Figures

FIGURE 5. Allonothrus tuxtlasensis (adult female): a—right leg I, abaxial view; b—right leg II (slightly broken), femur and genu dorsal view, tibia and tarsus abaxial view; c—right leg III, femur to tarsus, adaxial view; d—left leg IV, abaxial view. Scale bar 50 µm.

FIGURE 6. Allonothrus tuxtlasensis (adult female, light micrographs): a—subcapitulum, ventral view (palps removed); b— postpalpal seta; c—ovipositor, lateral view (anterior to top); d—three coronal setae (k) of ovipositor; e—seta τ1 and unidentified strongly bent τ-seta on anterior lobe of ovipositor; f—genu I, dorsal view; g—same, different specimen; h—as in g, but deeper focus to show canal of minute solenidion σ m; i—genu and tibia II, dorsal view; j—genu III, dorsal view. Scale bars 10 µm (a–c), 5 µm (d–j).