Trichonothrus hallidayi, Colloff, Matthew J., 2011

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 : 31-35

Trichonothrus hallidayi sp. nov.

( Figs. 20–22 a, 23, 24)

Dimensions. Holotype female length 1231, breadth 613 μm; paratype females (n = 7) mean length 1252 μm (range 1201–1311 μm), mean breadth 644 μm (range 613–695 μm); paratype males (n = 10) mean length 1137 μm (range 1098–1177 μm), mean breadth 562 μm (range 545–600 μm).

Female. Prodorsum: Rostrum pointed, with triangular hyaline median region; rostral seta (ro) 85 μm long, setiform, reflexed, sparingly barbed basally; base positioned half its length from apex of rostrum ( Fig. 20 a). Lamellar seta (le) 96 μm long, stout, heavily barbed, emerging from well-developed conical tubercle on lateral margin of prodorsum. Prodorsal margin greatly expanded posteriolateral of le, then strongly invaginated dorsal of acetabulum of leg I. Interlamellar seta (in) phylliform, densely barbed, 122 μm long, almost as long as the distance between them. Bothridial seta flagelliform, smooth, 332 μm long, apex reflexed. Exobothridial seta (ex) prominent, 70 μm long, strongly barbed, positioned posteriolateral of bothridial rim, base visible in dorsal view. Prodorsum with small, sparsely-scattered alveoli.

Notogaster: Ratio of length to breadth 1.28. Notogaster elongate, sub-oval, margins convex; with circumdorsal scissure ( Fig. 20 a). Notogastral cuticle with large irregular alveoli (5–12 μm diameter), sparsely-distributed (10–17 μm apart). Notogastral setae slightly curved, strongly barbed, 35–52 μm long; c 3 in humeral position; c 2 displaced posteriomedially. Centrodorsal plate with four pairs of setae (c 2, d 1-2, e 1). Distance between setae c 1 0.7 × that between c 1 and c 3; distance between setae c 1 0.8 × that between c 2 and 0.5 × that between d 1; distance between d 2 0.9 × that between d 1; distance between e 1 1.3 × that between f 1. Caudal margin rounded.

Subcapitulum: Mentum smooth; gena with three setae: seta a 63 μm long, setiform; m 1-2 sub-equal in length (26 μm), expanded basally, narrow and pointed apically ( Fig. 21 a). Palp setal formula (solenidion in brackets) 0-1-1-3- 9(1). Palp femur with very long (90 μm), barbed seta inf ( Fig. 21 c). Adoral setae sub-equal in length (51μm), strongly-curved, bacilliform, ( Fig. 21 b).

Coxisternum: Epimeral plates III and IV separated along sternal line, I and II adjacent ( Fig. 20 b). Epimeral setal formula: 15-7-7-11. Epimeral setae very long (127–175 μm), barbed, expanded basally, flagelliform apically. Epimeral plates I–III sub-rectangular; plates I with acetabular spur posteriolaterally; plate IV triangular.

Anogenital Region: Each genital plate 245 μm long, 88 μm broad, with nine setiform setae, 55–82 μm long, inflated and barbed basally, all arranged in median file ( Fig. 20 b). Pre-anal plate narrow, rectangular, 99 μm broad. Each anal plate 309 μm long, 64 μm broad, with two barbed setae, 50 μm long; one on anterior, one on posterior part of plate. Adanal setae barbed, longer than anal setae (67 μm). Ventral margin of notogaster posterior of anal plates entire, rounded.

Lateral view: Prodorsal margin anterior of ro slightly concave, vertical; expanded region lateral of le extending as far as mentum; ventral margin of prodorsum undulating ( Fig. 20 c). Seta le projecting as far as base of ro, cuticle between them straight; region posterior of le inflated, concave posterior of inflation. Abjugal furrow not evident. Exobothridial seta ex 1 just posterior of bothridial rim; ex 2 represented by alveolus. Lyrifissure ia 30 μm long. Hysterosoma box-like. Notogastral shield flat between setae c 1 and h 1. Ratio of notogastral height to length 0.65. Suprapleural scissure well-developed, straight; pleuraspis trapezoid. Caudal margin of notogaster vertical; adanal plate prominent, projecting beyond ventral margin of notogaster.

Legs: pre-tarsus heterotridactylous. Tarsi with thin, smooth or sparingly-barbed setiform setae on distal part and long, thick, phylliform, heavily-barbed setae on proximal part ( Fig. 22 a). Other segments entirely or predominantly with thick, barbed setae. Setal formula of Leg I (solenidia in brackets): 1-6-6(1)-6(2)-28(3).

Protonymph. Length 778 μm, breadth 369 μm. Entire surface of body covered in cerotegument consisting of clusters of short conical spines ( Fig. 23 a). Prodorsum: Length 255 μm. Rostral seta ro curved, smooth, 49 μm long; lamellar setae le straight, heavily barbed, 67 μm long; le at apex of parallel ridges extending from interlamellar setae in. Prodorsal margin greatly expanded posteriolateral of le, then strongly invaginated dorsal of acetabulum of leg I. Seta in 30 μm long, heavily barbed. Bothridial seta bs smooth, elongated (245 μm), flagelliform and recurved apically. Exobothridial seta ex 31 μm long, heavily barbed. Gastronotic region: Length 523 μm; elongate, sub-oval, margins convex, broadest at level between setae cp and e 2; circumdorsal scissure absent ( Fig. 23 a). Gastronotic setae heavily barbed, sub-equal in length (30–43 μm). Distance between bases of setae c 1 and bases of c 2 and d 2 sub-equal, 0.7 × that between bases of c 1 and c 3; distance between bases of setae d 2 1.2 × that between bases of setae c 1. Caudal margin rounded. Subcapitulum: Gena with setae a and m 1-2. Coxisternum: Epimeral setae barbed; formula 4-3-4-2 ( Fig. 23 b). Anogenital Region: Each genital plate 61 μm long, 27 μm broad, with one barbed seta ( Fig. 23 a). Each anal plate 195 μm long, 49 μm broad. Setae of p series distributed peri-anally; p 2 and p 3 slightly longer (43 μm) than p 1 (27 μm).

Tritonymph. As for protonymph except as follows: length 1252 μm, breadth 682 μm. Prodorsum: Length 308 μm. Rostral seta (ro) smooth, 87 μm long. Lamellar seta (le) 91 μm long ( Fig. 24 a). Gastronotic region: Length 944 μm. Subcapitulum: Gena with setae a and m 1-2. Coxisternum: Epimeral setal formula 10-6-6-7 ( Fig. 24 b). Anogenital Region: Each genital plate 127 μm long, 60 μm broad, with seven long (54 μm), barbed setae ( Fig. 24 b). Each anal plate 295 μm long, 54 μm broad.

Material examined. Holotype, four paratype females, four paratype males, ANIC 297, moss and litter, rain forest with Nothofagus cunninghami, Cumberland Creek Valley , nr. Cumberland Memorial Picnic Area [Cumberland Scenic Reserve], Yarra Ranges National Park, Victoria. 37°34'S 145°52'E, 920 m., coll. R.W. Taylor & R.J. Bartell, 4.ix.1970. One paratype female, ANIC 300, litter, fern gully, Cement Creek, Warburton, Victoria. 37°42’S 145°44’E, 640 m., coll. R.W. Taylor & R.J. Bartell, 5.ix.1970. Five paratype males, FM (HD) 78-125, fungus bait in Nothofagus cunninghami forest, Cement Creek, Warburton, Victoria, 500 m., S. & J. Peck, 7.v.1978. Three paratype females, FM (HD) 80-175, litter, Eucalyptus forest with tree ferns, Coranderrk Reserve, south-east of Healesville, Victoria, ca. 240 m., A. Newton & M. Thayer, 13.i.1980. Non-type material: five nymphs, ANIC 297, 300. Holotype and paratypes from ANIC samples deposited in the Australian National Insect Collection, CSIRO Ecosystem Sciences, Canberra. Two paratypes from ANIC samples in Roy A. Norton Collection, College of Environmental Science and Forestry, State University of New York, Syracuse. Other paratypes in Field Museum, Chicago.

Etymology. This species is named in honour of my friend and colleague, Dr Bruce Halliday (Australian National Insect Collection, CSIRO Ecosystem Sciences) in recognition of his research contribution to acarology.

Remarks. Trichonothrus hallidayi can be differentiated from the only other member of the genus, T. austroafricanus Mahunka, 1986 , based on the following combination of characters: 1) the large, stout, heavily barbed lamellar setae; 2) the strongly inflated lateral prodorsal region; 3) the stout, heavily barbed exobothridial setae; 4) with notogastral seta c 2 displaced posteriomedially; 5) with a complete circumdorsal scissure; 6) with four pairs of setae on the centrodorsal region enclosed by the circumdorsal scissure; 7) notogaster oval; posterior margin rounded; 8) epimeral setae long, flagellate apically and barbed basally; 9) epimeral setal formula 15-7-7-11; 10) genital setae aligned medially; long, stout, pointed and barbed apically; 11) gena entire, not divided by a sclerotised ridge.

Figures

FIGURE 20. Trichonothrus hallidayi sp. nov., holotype female; a) dorsal; b) ventral; c) lateral.

FIGURE 21. Trichonothrus hallidayi sp. nov., paratype female; a) subcapitulum b) oral setae; c) palp.

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

FIGURE 23. Trichonothrus hallidayi sp. nov., protonymph; a) dorsal; b) ventral.

FIGURE 24. Trichonothrus hallidayi sp. nov., tritonymph; a) dorsal; b) ventral.