Trichonothrus austroafricanus Mahunka, 1986

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 : 36-38

Trichonothrus austroafricanus Mahunka, 1986

( Figs. 22 b, 25)

Trichonothrus austroafricanus Mahunka, 1986 , 50, figs. 19–22.

Trichonothrus austroafricanus Mahunka : Palmer & Norton, 1991, 79.

Dimensions. Male length 1106 μm, breadth 545 μm.

Supplementary description. Male. Prodorsum: Rostrum pointed, reticulate, with triangular hyaline median region; rostral seta (ro) 37 μm long, setiform, reflexed, sparingly barbed ( Fig. 25 a). Lamellar seta (le) 69 μm long, stout, spiniform, slightly curved, sparingly barbed, emerging from well-developed tubercle on lateral margin. Margin slightly expanded lateral of le, then concave dorsal of acetabulum of leg I. Interlamellar seta (in) phylliform, densely barbed, 70 μm long, half as long as the distance between them. Bothridial seta flagelliform, smooth, 332 μm long, apex reflexed. Exobothridial seta (ex) prominent, 60 μm long, smooth, spiniform, positioned posteriolateral of bothridial rim. Prodorsum with small, sparsely-scattered alveoli.

Notogaster: Ratio of length to breadth 1.35. Notogaster elongate, sub-oval, margins convex; with incomplete circumdorsal scissure, merging with dorsosejugal suture anteriorly ( Fig. 25 a). Notogastral cuticle with small irregular alveoli (7–15 μm diameter), sparsely-distributed (9–15 μm apart). Notogastral setae straight or slightly curved, strongly barbed, 45–64 μm long; c series aligned; c 2 not displaced posteriomedially. Centrodorsal plate with six pairs of setae (c 1-2, d 1-2, e 1 f 1). Distance between setae c 1 1.5 × that between c 1 and c 2; distance between setae c 1 0.7 × that between d 1; distance between d 2 1.2 × that between d 1; distance between e 1 1.6 × that between f 1. Caudal margin transverse.

Subcapitulum: Mentum foveolate; gena with transverse sclerotised ridge posterior of m 1; with three setae: seta a 55 μm long, curved, setiform; m 1-2 sub-equal in length (20 μm) straight, setiform, smooth ( Fig. 25 b).

Coxisternum: Epimeral plates I–III adjacent; IV separated along sternal line ( Fig. 25 b). Epimeral setal formula: (12,14)-5-5-5. Epimeral setae spiniform, rough, thick, pointed, 17–32 μm long. Epimeral plates I–III sub-rectangular; plates I with prominent acetabular spur posteriolaterally; plate IV triangular.

Anogenital Region: Each genital plate 164 μm long, 109 μm broad, with nine sparingly barbed, spiniform setae, 44–55 μm long, five in median file, four in lateral file ( Fig. 25 b). Pre-anal plate sub-triangular, 114 μm broad. Each anal plate 273 μm long, 57 μm broad, with two barbed setae, 34–40 μm long; one on anterior, one on posterior part of plate. Adanal setae densely barbed, longer (56 μm) than anal setae. Ventral margin of notogaster posterior of anal plates entire, rounded.

Lateral view: Prodorsal margin anterior of ro convex; between le and ro slightly concave; vertical; expanded region lateral of le extending ventrally as far as mentum ( Fig. 25 c). Seta le projecting at least as far as base of ro, region posterior of le inflated, then concave. Exobothridial seta ex just posterior of bothridial rim; alveolus of ex 2 not evident. Lyrifissure ia 25 μm long. Hysterosoma inflated, box-like. Notogastral shield flat between setae c 1 and e 1 then curved. Ratio of notogastral height to length 0.6. Suprapleural scissure well-developed, straight; pleuraspis trapezoid. Caudal margin of notogaster vertical; adanal plates prominent, projecting beyond ventral margin of notogaster.

Legs: Pre-tarsus heterotridactylous. Tarsi with thin, smooth setiform setae on distal part and long, thick, phylliform, sparingly-barbed setae on proximal part ( Fig. 22 b). Other segments entirely or predominantly with thick, barbed setae. Setal formula of Leg I (solenidia in brackets): 1-7-5(1)-6(2)-24(3).

Material examined. Two females, two males, RAN 79-101 [SR 248], forest litter, World’s View, near Pietermaritzburg, South Africa, 29°34'S 30°19'E, ca. 1020 m., coll. B. Lamoral, iii.1974.

Remarks. The differences between Trichonothrus austroafricanus and T. hallidayi were described above. There are minor differences between Mahunka’s (1986) description and the supplementary description herein. The specimens I examined have stout spiniform lamellar setae and epimeral setae with few barbs, rather than heavily barbed; the numbers of epimeral setae and their arrangement are slightly different, (12,14)-5-5-5 compared with 15-5-7-7, and the specimens I examined lack the posteriolateral extensions of the circumdorsal scissure illustrated by Mahunka (1986).

Trichonothrus austroafricanus was described from material collected from litter at Garden of Eden, south Cape, South Africa. Based on the latitude and longitude given by Mahunka (1986), this is a native forest site, near the coast, within Harkerville Forest Reserve near Knynsa, Western Cape. The material used for the supplementary description was also from forest litter at World’s View, near Pietermaritzburg. The new species from Victoria, T. hallidayi , is from moss and litter, in cool temperate Nothofagus cunninghami rain forest and wet sclerophyllous Eucalyptus forest.

Figures

FIGURE 22. Trichonothrus spp., Legs I, left antiaxial aspect; a) T. hallidayi sp. nov.; b) T. austroafricanus.

FIGURE 25. Trichonothrus austroafricanus Mahunka, 1986, adult male; a) dorsal; b) ventral; c) lateral.