Topalia royi, Colloff, 2019

Colloff, Matthew J., 2019, The oribatid mite genus Topalia in Australia (Oribatida: Nosybeidae) and the taxonomic status of related families and genera, Zootaxa 4647 (1), pp. 290-321 : 300-303

Topalia royi sp. nov.

Topalia sp. 2: Hunt et al. (1998)

( Figs. 7 , 8 , 9b )

Dimensions. holotype: length 340, breadth 195; paratype 1: length 363, breadth 212; paratype 2: length 355, breadth 208. Ratio of prodorsum to total length: 0.36 (holotype).

Adult. Integument: notogaster with network of large, deep, angular foveolae interspersed with globular tubercles of varying size. Underlying cuticle smooth.

Prodorsum: rostrum incised. Lamellae separated along midline and with pattern of fine, curved striae, with narrow anterior translamella positioned ventrally. Interlamellar region flat, smooth, bearing squat tubercles of setae in. Bothridial seta short, with attenuated club-shaped apices with blunt spines.

Notogaster: ratio of length to breadth: 1.12. Anterior margin of notogaster transverse, wavy, concave medially. Rounded humeral projections (h) positioned anterolaterally on notogaster, bearing minute seta c 2. Margins of centrodorsal ridge well-developed, closely convergent anterior of setae dm, then diverging posteriorly. Posterior part of ridge broadly rounded, extending to point posterior of level of setae h 3. Notogastral setae on squat tubercles.

Ventral aspect: epimeral plates I one-third longer than broad; sub-rectangular to trapezoid; epimera III and IV partly fused transversely and along mid-line; epimeral setation 2-1-2-3. Pedotectum I extending anteriorly about one-third of length of lamellae. Pedotectum II extending laterally as far as margin of humeral projections, with strong, dorsally-curved, pointed apex. Perigenital carina narrow, strongly curved, ca. 40 µm long, extending posteriorly to point level with seta ag. Genital plates 45 µm long, same length as anal plates and twice distance between them. Subcapitulum elongated (72 µm long) and narrow; chelicera thin, narrow, elongate, sub-pelopsiform; movable digit with reduced teeth ( Fig. 8b ).

Lateral aspect: apices of lamellar cusps slightly curved ventrally. Interlamellar region slightly domed, level with highest part of centrodorsal ridge. Anterior margin of rostrum between tutorium (tu) and rostral seta straight, diagonal. Tutorium with short free cusp. Anterior margin of pedotectum I rounded, convex. Centrodorsal ridge low and flat, extending posteriorly as far as level of lyrifissure ih; region just posterior slightly concave.

Legs: Tarsus I with 15 setae, including short setiform famulus; solenidia ω 1 and ω 2 subequal in length (30 µm); tibia I with solenidion φ 1 very long (110 µm), flagelliform, arising free on tarsal cuticle and set back from articulation with tibia. Genu I without setae, bearing short solenidion σ only; femur I with one dorsal and one ventral seta ( Fig. 8a ).

Material Examined and Locality Data. Holotype and two paratypes: ANIC 460 , leaf litter, rainforest, O’Reilly’s Rainforest Retreat, Lamington National Park , Queensland, 28°13’58”S 153° 8’17”E, c. 920 m, coll. R.J. Kohout, 21.iii.1973.

Etymology. This species is named in honour and memory of Dr Alexander “Sandy” Bilton Roy in recognition of his nearly twenty years of volunteer work devoted to the curation and cataloguing of spiders, mites, ticks and termites in the Australian National Insect Collection.

Diagnosis. Topalia royi sp. nov. can be distinguished from other species in the genus by the following combination of characters: (1) the rostrum incised medially; (2) the anteromedial edges of lamellae separated; (3) the partly fused epimera III and IV; (4) the medially indented anterior notogastral margin; (4) the laterally-positioned humeral projections; (5) the cerotegument consisting of a network of large, deep, angular foveolae; (6) the epimeral setation 2-1-2-3.

Remarks. Topalia royi sp. nov. is morphologically most similar to Topalia caliginosa sp. nov., as detailed above.

Topalia sp. 2 ( Hunt et al., 1998) was collected from the same location as T. royi (leaf litter, O’Reilly’s Rainforest Retreat, Lamington National Park, Queensland (28º14’S 153º08’E) coll. R. Kitching) and I consider it to be T. royi sp. nov. They share the characteristic pattern of cerotegument, faint striae on the lamellar cusps, equal ratios of prodorsal length to total length, notogastral length to breadth, and the morphology of the bothridial setae ( Fig. 9b ). When the figure of the dorsal aspect of T. royi sp. nov. is superimposed on the scanning electron micrograph of Topalia sp. 2, it fits almost exactly the outline of the lamellae and notogaster.

Figures

FIGURE 7. Topalia royi sp. nov. (a) dorsal aspect; (b) ventral aspect; (c) lateral aspect; (d) cerotegument. Scale bar = 100 µm.

FIGURE 8. Topalia royi sp. nov. (a) left leg I; (b) chelicera; scale bars: (a) = 100 µm; (b) = 25 µm.

FIGURE 9. Scanning electron micrographs of dorsal aspects of (a) Topalia sp. 1 and (b) Topalia royi sp. nov. (Topalia sp. 2) (from Hunt et al. 1998).