Novonothrus Balogh, 1972

Colloff, Matthew J., 2011, A review of the oribatid mite family Nothridae in Australia, with new species of Novonothrus and Trichonothrus from rain forest and their Gondwanan biogeographical affinities (Acari: Oribatida), Zootaxa 3005, pp. 1-44 : 4

Novonothrus Balogh, 1972

Novonothrus Balogh, 1972

Type species Novonothrus flagellatus Hammer, 1966

Hammer’s ( 1966) definition of Novonothrus was as follows: tip of rostrum with a round fissure; with paired lighter areas of cuticle posterior of rostral setae; prodorsum with a broad lateral protuberance or expansion anterior of legs I; exobothridial setae present; bothridial setae long and flagelliform, with numerous small ‘glands’ in the bothridium. Epimeral plates fused medially; aggenital setae absent; caudal margin rounded. Balogh’s (1972) definition, based on a key and a table, was as follows: nothroid mites with a sensillus; monodactylous; with nine pairs of genital setae; aggenital setae absent; two pairs of anal setae, three pairs of adanal setae and epimeral setal formula 9-5- 6-5 or 9-6-6-5. Both definitions are inadequate to contain all species of Novonothrus , do not include characters of the immatures, and some character states are shared with other genera within the Nothrina, for example, the expanded lateral prodorsal region is found in Heminothrus , Trichonothrus and Nothrus . The genus is therefore redefined below.

Apex of rostrum inverted U-shaped, consisting of lateral projections extending anteriomedially and median oval region of lighter cuticle. Cuticle lacking slit-like median incision; with paired lighter areas of cuticle posterior to rostral setae and anterior to lamellar setae. Prodorsum alveolate. Exobothridial seta ex 1 present, and alveolus of ex 2; with or without three pairs of lateral prodorsal setae, l 1-3. Bothridial seta long, flagelliform, recurved apically, smooth, never barbed. Bothridial rim triangular, bothridium with internal porose saccules, arranged radially in dorsal view. Adult and nymphs with 16 pairs of notogastral setae; those of h series sub-equal in length in adult, h 2 occasionally longer than others in immatures. Hysterosoma expanded. Notogaster with faint lateral ridges. Suprapleural scissure absent: notaspis and pleuraspis fused, convex, rounded. Epimeral plates separated along sternal line in immatures; at least epimeral plates III and IV separated in adults. Genital plates divided transversely, each with six setae arranged in median file and three in lateral file. Aggenital setae absent; two pairs of anal setae; three pairs of adanal setae. Epimeral plates I with 5–9 setae; II with 4–6; III with 5–6; IV with 5–6.

Remarks. The differential diagnosis of Novonothrus from Nothrus and Trichonothrus is based on the following characters: 1) the presence of the paired lighter areas of cuticle anterior of the lamellar setae and posterior of the rostral setae, absent in Nothrus and Trichonothrus ; 2) the rostral incision is in the form of a median oval region, the lateral margin demarcated by paired, curved, converging digitate projections, unfused medially and overlain with lightly-sclerotised cuticle, described by Hammer, 1966 as a ‘hyaline membrane’(Fig. 11f). In Nothrus the rostrum has a short, longitudinal notch and in Trichonothrus the rostrum is entire; 3) the presence of a smooth, setiform or spiniform exobothridial seta ex 1 and alveolus of ex 2; in Nothrus the exobothridial seta is minute or absent, in Trichonothrus it is barbed or smooth and very long, almost as long as the interlamellar seta; 4) the fusion of the notaspis and pleuraspis, with the suprapleural scissure absent or marked by a faint ridge or fold; 5) the convex, rounded notaspis and pleuraspis: in Nothrus and Trichonothrus the notaspis is more-or-less flat; 6) the transverse division of the genital plates, absent in Nothrus and Trichonothrus ; 7) the smooth, apically-flagelliform bothridial setae are shared with Trichonothrus , but in Nothrus they are fusiform apically, occasionally barbed or ciliate but never flagelliform or strongly re-curved.