Malaconothrus dispela, 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 : 410-413

Malaconothrus dispela sp. nov.

(Figs. 6, 7)

Dimensions. Holotype female length 368 Μm, breadth 167 Μm. Paratype female lengths 381, 366 Μm, breadths 164, 170 Μm. Ratio of prodorsum to total length: 0.4 (holotype).

Female. Prodorsum. Rostrum acute, U-shaped (Fig. 6a). Rostral seta (ro) thin, 4 Μm long, smooth, emerging from alveolus ventral to apex of carina. Lamellar seta (le) smooth, sub-equal in length to ro, emerging from alveolus medial of carina. Interlamellar seta (in) smooth, setiform, 22 Μm long, 4 × longer than smooth exobothridial seta ex. Prodorsum finely porose; cerotegument of small, angular foveolae.

Notogaster. Anterior notogastral margin slightly convex; humeral region rounded (Fig. 6a). With 15 pairs of short, smooth, setiform setae. Setae mostly sub-equal in length (20–27 Μm), d 1, e 1, h 2 and h 3 longer (37–46 Μm). Seta c 1 same distance from c 2 as from c 2 to c 3. Notogaster shield-shaped, margins more-or-less parallel, broadest at level of cp. Without notogastral ridges. Ratio of length to breadth 1.3. Caudal margin slightly indented at level of h 2; V-shaped. Cerotegument of small, angular foveolae (Fig. 6d).

Coxisternum. Epimeral setal formula 3-1-3-3 (Fig. 6b). Seta 3b and 4a longest (21–24 Μm), much longer than other epimeral setae. Epimeral plates I and III fused anteriorly; II fused posteriorly; IV separated. Epimeral plates I with prominent spur anterolaterally. Epimeral plates II acute posterolaterally. Epimeres III and IV of equal width. Apodeme IV strongly concave.

Anogenital Region. With six pairs of genital setae; g 1-5 barbed (Figs 6b,c); g 6 spiniform, smooth, longer than others (26 Μm), positioned three times distance from g 5 than from g 5 to g 4. Each genital plate 77 Μm long, 29 Μm broad, ovoid, elongated; posterior margin transverse. One pair of anal setae 6 Μm long. Each adanal plate 70 Μm long, 11 Μm broad, with three pairs of smooth, setiform adanal setae, 13–16 Μm long, shorter than width of adanal plate. Anterior margin of adanal plate without thickened transverse ridge, overlapped by posterior margin of genital plate.

FIGURE 6. Malaconothrus dispela sp. nov., holotype female; a) dorsal; b) ventral; c) detail of genital seta g 5; d) detail of notogastral cerotegument.

Legs. Pre-tarsi monodactylous ( Fig. 7 ). Legs short and broad: Leg I 104 Μm long; tarsi sub-rectangular with prominent apophysis of setae ft ”. Ratio of length to breadth: I 1.7; II 1.7; III 2.1; IV 2.6. Setal formula: Leg I 1-4 - 2(1)-4(1)-11(3); Leg II 1-3 -1(1)-2(1)-10(1); Leg III 2-2 -1-2(1)-10; Leg IV 1-2 -1-2-10. Leg setae smooth. Proral (p) and unguinal setae (u) on all tarsi short, broad, peg-like, blunt apically ( Fig. 7 ). Tarsus I with solenidion ω1 posterodorsal of ω2-3; famulus (ε) short (3 Μm), spine like; fastigial setae (ft) heteromorphic: ft ” short, blunt, curved, very broad, emerging from prominent conical apophysis ( Fig. 7 a); ft ’ long, broad, curved, pointed. Tarsi II–IV and II with ft similarly heteromorphic ( Fig. 7 b,c,d). Tarsus IV with seta s same length and shape as primiventral setae (pv) ( Fig. 7 d).

Material Examined. Holotype and two paratypes, ANIC 418, litter, rainforest, Highlands Highway, near Komum (ca. 15 km east of Mt. Hagen), Papua New Guinea, 5°49'43"S 144°22'19"E, 1830 m., coll. G. Baker, 16.vii.1972. Holotype and paratypes deposited in the Australian National Insect Collection, CSIRO Ecosystem Sciences, Canberra.

Etymology. The specific name dispela is Tok Pisin (the official language of Papua New Guinea) for ‘this one’, derived from the English, ‘this fellow’.

Remarks. Malaconothrus dispela sp. nov. differs from other members of the genus by the following combination of characters: 1) the shield-shaped notogaster with the caudal region V shaped; 2) with notogastral setae d 1, e 1 and h 2 longer than others; 3) notogaster without posterior or lateral ridges; 4) epimeral plates II acute posterolaterally; 5) the epimeral setae 3b and 4c longer than others; 6) the six pairs of genital setae; 7) the genital setae are heteromorphic: g 5 is spiniform and smooth, the others are setiform and barbed; 8) seta g 5 spaced some distance from the next most posterior seta.

Malaconothrus dispela sp. nov. is morphologically most similar to M. pygmaeus Aoki, 1969 , M. neonominatus Subías, 2004 (= M. pulcher Hammer, 1961 ), M. minutus Fujikawa, 2005 and M. setoumi Fujikawa, 2005 . These species are members of the Monodactylus species group (cf. below). All the species mentioned above have barbed genital setae, but the latter two species have five pairs all of which are barbed; M. neonominatus has six pairs, all barbed, but much longer marginal notogastral setae, especially h 2, than M. dispela . Malaconothrus pygmaeus , like M. dispela , has six pairs, but g 1-4 are barbed and g 5-6 are smooth according to the supplementary description by Yamamoto (1998), whereas in M. dispela g 1-5 are barbed and g 6 is smooth. Malaconothrus pygmaeus and M. dispela have the epimeral setal formula 3-1-3-3 (seta 3b is present), whereas in M. neonominatus it is 3-1-2-3 (seta 3b is absent). In M. pygmaeus and M. neonominatus setae 4a, 4c and 3c are sub-equal in length, whereas in M. dispela setae 3b and 4c are each about twice the length of the other two setae. Finally, the notogastral cerotegument of M. neonominatus is of closely-spaced ovoid foveolae of similar size, whereas in M. pygmaeus the foveolae are broadly-separated ovoids greatly varying in size and in M. dispela they are of equal size, sub-pentagonal or hexagonal and regularly and closely spaced with clearly-defined ridges between them.

Figures

FIGURE 7. Malaconothrus dispela sp. nov., left legs, left-hand view; a) Leg I; b) Leg II; c) Leg III; d) Leg IV.