Malaconothrus weigmanni, 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 : 416-419

Malaconothrus weigmanni sp. nov.

( Figs. 10 , 11 )

Dimensions. Holotype female length 450 Μm, breadth 253 Μm. Paratype female length, 444 Μm, breadth 246 Μm. Ratio of prodorsum to total length: 0.3 (holotype).

Female. Prodorsum. Rostrum broad, rounded, smooth. Rostral seta (ro) smooth, curved ventrolaterally, setiform, 34 Μm long, shorter than distance between them, emerging from apex of simple, curved carinae lacking medial extensions ( Fig. 10 a). Lamellar seta (le) smooth, setiform, 51 Μm long, as long as distance between them, extending anteriorly beyond base of seta ro, emerging medial of most convex region of carina. Interlamellar seta (in) smooth, stout, setiform, 113 Μm long, longer than distance between them. Exobothridial seta ex smooth, 41 Μm long. Pedotectum I well-developed, blunt. Prodorsum smooth, porose.

Notogaster. Anterior notogastral margin slightly convex, cerotegument strongly reticulate laterally, becoming fainter medially ( Fig. 10 a). Humeral region rounded. Lyrifissure ia 20 Μm long. With 15 pairs of long, overlapping, stout, smooth, setiform notogastral setae. Setae c 1, d 1 and e 1 much longer (105–127 Μm) than others (71–88 Μm). Seta c 2 much closer to c 3 than to c 1; f 1 represented by alveolar vestige. Faint posterior M-shaped ridge, indented at level of seta h 2, with faint, curved transverse ridge anterior of p 1. Lateral longitudinal ridges absent. Longitudinal ridges absent lateral of anal and genital plates; ventral concave ridge between caudal margin and seta h 3 ( Fig. 8 b). Setae p 3 positioned markedly anterior of p 2. Notogaster broad, shield-shaped; margins convex, broadest at level of e 2. Ratio of length to breadth 1.2. Caudal margin transverse. Lyrifissurae ip acute.

Coxisternum. Epimeral setal formula 3-1-3-3 ( Fig. 10 b). Epimeral setae smooth, setiform; 3b, 3c and 4c 35–45 Μm long, much longer than others (6–20 Μm); 1c and 4b in posterolateral position, 3b in mediolateral position. Epimeral plates I and IV separated, II fused anteriorly, III fused posteriorly. Posterolateral margins of epimeral plates II pointed, sharp. Apodeme IV, as far as posterolateral acetabulum, concave. Sejugal articulation narrower than epimeral plates II.

Anogenital Region. With four pairs of thin, smooth, setiform genital setae ( Fig. 10 b), g 1-3 subequal in length (24–28 Μm), g 4 36 Μm long, directed anteriorly; distance between insertions of g 3 and g 4 2 × that between g 2 and g 3. Setae shorter than width of genital plate. Each genital plate 90 Μm long, 52 Μm broad, sub-oval with transverse posterior margin. Without reticulate or striated cerotegument between adanal plate and ventral margin of notogaster. One pair of short (11 Μm) setiform anal setae, as long as width of anal plate. Each adanal plate 92 Μm long, 34 Μm broad; three pairs of long (62–88 Μm) smooth, setiform adanal setae, longer than width of adanal plate; ad 1 longer than others, not on median carina. Anterior margin of adanal plate acute, overlapped by posterior margin of genital plate, without thickened transverse ridge.

Lateral Aspect. Prodorsum smoothly curved from seta le to apex of rostrum; flat between le and in ( Fig. 10 c). Seta le projecting anterior of base of seta ro. Seta ex projecting posteriolaterally; seta ex 2 represented by alveolar vestige. Pedotectum I well-developed, semi-circular. Interbothridial region flat. Hysterosoma strongly dorsoventrally flattened. Notaspis flat between setae c 1 and h 1: ratio of height to length 0.3 Pleuraspis with long, broad, semi-circular humeral process almost covering acetabulum III.

Legs: Pre-tarsi heterotridactylous. Legs short and broad ( Fig. 11 ): Leg I 154 Μm long; tarsi sub-conical. Ratio of length to breadth of Tarsi: I 1.8; II 1.9; III 2.9; IV 3.3. Setal formula: Leg I 1-5 -2(1)-3(1)-11(3); Leg II 1-6 -2(1)- 3(1)-10(1); Leg III 2-3 -2-2(1)-10; Leg IV 0- 2 -2-2-10. Tarsus I with proral setae (p) short, broad basally, flagelliform apically ( Fig. 11 a): short, blunt and broad on other tarsi; unguinal setae (u) short, blunt and broad: peglike; solenidia ω2-3 positioned anteriorly: separated from ω1; famulus (ε) minute, conical (2 Μm); fastigial setae (ft) heteromorphic: ft ” short, blunt and broad and ft ’ longer, broad basally, tapering and pointed apically. Tarsus II with setae ft as for Tarsus I ( Fig. 11 b). Tarsus II both setae ft long, broad basally, pointed apically ( Fig. 9 c). Tarsus IV with ft” long (43 Μm), curved, pointed; seta s same shape but slightly longer than primiventral setae (pv) ( Fig. 11 d). Tectal seta tc ’ longer than tc ” on all tarsi. Setae on femora very long: va and vm on Femur II 50 Μm and 63 Μm long respectively; seta d on Femur IV very thick, massive, 86 Μm long.

Material examined. Holotype and paratype, ANIC 396, litter, rainforest, McAdam National Park near Wau, Papua New Guinea, 7°14'33"S 146°36'30"E, 1250 m., coll. R.W. Taylor, 14.vi.1972. Holotype and paratype deposited in the Australian National Insect Collection, CSIRO Ecosystem Sciences, Canberra.

Etymology. This species is named in honour of Professor Gerd Weigmann (Institut für Zoologie, Freie Universität Berlin, Germany) in recognition of his contribution to research on the systematics and ecology of oribatid mites.

Remarks. Malaconothrus weigmanni sp. nov. differs from other members of the genus by the following combination of characters: 1) with rostral setae slightly shorter than lamellar setae and positioned at apices of slightly curved prodorsal carinae; 2) with setae in twice length of ex; 3) the reticulate notogastral cerotegument; 4) the very broad notogaster with a length-to-breadth ratio of 1.2; 4) the robust, thick notogastral setae; 5) the median setae c 1, d 1 and e 1 longer than the other notogastral setae and overlapping; 6) the shallow, M-shaped posterior notogastral ridges; 7) the faint, curved, transverse ridge anterior of p 1; 8) the four pairs of relatively long genital setae, with g 4 separated from the others and pointing anteriorly; 9) the very long flagelliform adanal setae, with ad 1 longer than the others.

Malaconothrus weigmanni is a member of the Opisthoseta species group (cf. below). It is morphologically most similar to M. repetitus (Subías, 2004) (= M. reticulatus [Yamamoto, 1977]). The notogaster of the latter species is similarly broad (length-to-breadth ratio 1.2) and the body setae are also long and thick. Malaconothrus repetitus lacks the M-shaped posterior notogastral ridges.

Figures

FIGURE 8. Malaconothrus gogolensis sp. nov., holotype female; a) dorsal; b) ventral.

FIGURE 9. Malaconothrus gogolensis sp. nov., left legs, left hand view; a) Leg I; b) Leg II; c) Leg III; d) Leg IV.

FIGURE 10. Malaconothrus weigmanni sp. nov., holotype female; a) dorsal; b) ventral; c) lateral.

FIGURE 11. Malaconothrus weigmanni sp. nov., left legs, left hand view; a) Leg I; b) Leg II; c) Leg III; d) Leg IV.