Malaconothrus tidbinbilla, Colloff, Matthew J., 2013

Colloff, Matthew J., 2013, Species-groups and biogeography of the oribatid mite family Malaconothridae (Oribatida: Malaconothroidea), with new species from the south-western Pacific region, Zootaxa 3722 (4), pp. 401-438 : 424-426

Malaconothrus tidbinbilla sp. nov.

( Fig. 15 )

Dimensions. Holotype female length 515 Μm, breadth 237 Μm; paratype female length 515 Μm, breadth 237 Μm. Ratio of prodorsum to total length: 0.3 (holotype).

Female. Prodorsum. Rostral seta (ro) curved, setiform, smooth, 51 Μm long, positioned at apex of slightly curved carina ( Fig. 15 a). Lamellar seta (le) smooth, setiform, 62 Μm long, as long as mutual distance, emerging medial of carina. Interlamellar seta (in) smooth, setiform, 84 Μm long, 4 × length of smooth exobothridial seta (ex). Prodorsum porose with densely alveolate cerotegument.

Notogaster. Anterior notogastral margin slightly convex; humeral region sharp, right-angled; lyrifissurae ia very long, positioned on well-developed longitudinal ridges ( Fig. 15 a). With 15 pairs of setiform, smooth setae, plus f 1 represented by their alveoli. Setae of the c, d and e series sub-equal in length (45–53 Μm); h 1, h 3 and p 1 slightly shorter than others; h 2 slightly longer. Bases of centrodorsal series not aligned longitudinally: mutual distance between d 1 less than between c 1 and e 1. With concave semicircular indentations extending between lyrifissurae ip and caudal mid-line median of p 1 forming curved ridges; lateral longitudinal ridges absent. Notogaster shield-shaped; margins more-or-less parallel, broadest at level of e 2. Caudal margin very slightly indented at level of h 2, otherwise U-shaped. Seta p 3 positioned markedly anterior of p 2 and half its length. Ratio of length to breadth 1.4. Lyrifissurae ip transverse. Notogaster porose with densely alveolate cerotegument.

Coxisternum. Epimeral setal formula 3-1-3-3 ( Fig. 15 b). Setae 1b, 3c and 4a longer (23–31 Μm) than others (6–17 Μm); setiform smooth; 1c in posterolateral position; 3 b medial; 4b posterolateral. Epimeral plates all separated. Epimeral plates I rounded anterolaterally, lacking blunt spine. Apodeme IV, as far as posterolateral acetabulum, strongly concave, with blunt spine

Anogenital Region. Genital plates with four pairs of smooth, flagelliform setae sub-equal in length (25–42 Μm), equally spaced ( Fig. 15 b). Each genital plate 98 Μm long, 45 Μm broad, sub-rectangular. One pair of long, smooth anal setae (17 Μm). Each adanal plate 127 Μm long, 25 Μm broad. Reticulate cerotegument in lightlysclerotised region between the adanal and notogastral plates. Three pairs of smooth, adanal setae sub-equal in length (42–59 Μm). Anterior margin of adanal plate acute; overlapped by posterior margin of genital plate.

Legs: Pre-tarsi heterotridactylous.

Material examined. Holotype and paratype, NAM 0 13, Hanging Rock, Tidbinbilla Nature Reserve, Australian Capital Territory, 35°28'21"S, 148°54'55"E, 840 m., coll. J. Bloszyk and S. Konwerski, 8.viii.2007. Holotype and paratype deposited in the Australian National Insect Collection, CSIRO Ecosystem Sciences, Canberra.

Etymology. This species is named for its type locality, the Tidbinbilla Nature Reserve.

Remarks. Trimalaconothrus tidbinbilla sp. nov. differs from other members of the genus by the following combination of characters: 1) the four pairs of flagelliform genital setae spaced equidistantly; 2) densely alveolate cerotegument; 3) the notogastral concavities; 4) the long humeral ridge with ia on it; 5) p 3 half the length of p 2; 6) epimeral plates I rounded anterolaterally; without well-developed spur; 7) very long setae 3c; 8) long anal setae; 9) setae 3b in medial position; 10) reticulate cerotegument present in the lightly-sclerotised region between the adanal and notogastral plates.

Malaconothrus tidbinbilla is morphologically most similar to M. jowettae Colloff & Cameron, 2013 . Both species have notogastral setae of similar lengths and arrangement, as well as long, thin flagelliform adanal and genital setae, but M. tidbinbilla has four pairs of genital setae and M. jowettae five pairs. The former species also has semicircular caudal ridges and Apodeme IV produced into a blunt spine posterolaterally, whereas in the latter species the ridges and spine are absent.

Figures

FIGURE 15. Malaconothrus tidbinbilla sp. nov., holotype female; a) dorsal; b) ventral.