Malaconothrus gogolensis, 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 : 413-416

Malaconothrus gogolensis sp. nov.

( Figs. 8 , 9 )

Dimensions. Holotype female length 353 Μm, breadth 151 Μm. Paratype female length 334 Μm, breadth 148 Μm. Ratio of prodorsum to total length: 0.4 (holotype).

Female. Prodorsum. Rostrum broad, U-shaped ( Fig. 8 a). Rostral seta (ro) minute (4 Μm long), smooth, positioned on squat tubercle on incurved apex of carina forming partial, transverse inter-rostral ridge. Lamellar seta (le) smooth, slightly longer than ro, emerging from alveolus medial of carina. Interlamellar seta (in) smooth, setiform, short (11 Μm), sub-equal in length and shape to adjacent exobothridial seta ex. Prodorsum finely porose; cerotegument of small, regular pits.

Notogaster. Anterior notogastral margin slightly convex; humeral region rounded ( Fig. 8 a). With 15 pairs of short, smooth, setiform setae. Setae mostly sub-equal in length (8–14 Μm), cp and h 2 longer (16–18 Μm), e 1 longest (23 Μm). Distance from c 1 to c 2 2.5 × c 2 to c 3. Notogaster rectangular, margins more-or-less parallel, broadest at level of c 3. With relatively broad median longitudinal ridges on which are positioned setae c 1 and d 1, joined with broad, transverse, double-curved posterior ridge on which are positioned setae h 1 and h 2. Median lobe of ridge reaching caudal margin between setae p 1. Lateral longitudinal ridges absent, but curved transverse ridge branching from medial ridge between e 1 and h 1, reaching lateral margin between f 2 and e 2. With curved transverse ridge from h 3 to caudal margin of ventral notogastral plate. Seta p 3 anterolateral of, and adjacent to, seta p 2. Ratio of length to breadth 1.4. Caudal margin slightly indented at level of h 2 and between p 2, otherwise U-shaped. Cerotegument with small, regular pits.

Coxisternum. Epimeral setal formula 3-1-3-2 ( Fig. 8 b). Setae 3b, 3c and 4c 13–1620 Μm long, 1b longest (21 Μm), much longer than other epimeral setae. Seta 3b in mediolateral position. Epimeral plates separated medially except II which is fused posteriorly. Epimeral plates I with well-developed spur anterolaterally. Epimeral plates II acute posterolaterally. Epimeres III and IV of equal width, without paired lateral spines. Apodeme IV strongly concave.

Anogenital Region. With four pairs of smooth, flagelliform genital setae; g 1 14 Μm long, g 2-4 22–30 Μm long, spaced equidistantly ( Fig. 8 b). Each genital plate 64 Μm long, 28 Μm broad, ovoid; posterior margin transverse. One pair of anal setae 7 Μm long. Each adanal plate 63 Μm long, 20 Μm broad, with three pairs of smooth, flagelliform adanal setae, 32–40 Μm long, longer than width of adanal plate. Anterior margin of adanal plate acute, without thickened transverse ridge, overlapped by posterior margin of genital plate.

Legs. Pre-tarsi monodactylous ( Fig. 9 ). Legs short and broad: Leg I 126 Μm long; tarsi sub-rectangular; ratio of length to breadth: I 1.6; II 1.7; III 1.7; IV 2.3. Setal formula: Leg I 1-4 -3(1)-3(1)-11(3); Leg II 1-5 -2(1)-3(1)- 10(1); Leg III 2-2 -2-2(1)-10; Leg IV 1-2 -1-2-10. Tarsal setae smooth; smooth or barbed on other segments. Tarsus I with proral setae (p) short, broad basally, flagelliform apically ( Fig. 9 a): short, blunt and broad on other tarsi; unguinal setae (u) short, blunt and broad: peg-like; solenidia ω1 posterodorsal of ω2-3; famulus (ε) short (3 Μm), broad, peg-like; fastigial setae (ft) heteromorphic: ft ” short, blunt and broad; ft ’ long, curved and pointed. Tarsus II and II with ft similarly heteromorphic ( Fig. 9 b,c). Tarsus IV with ft ” long (43 Μm), curved, pointed; seta s same length as primiventral setae (pv) but slightly curved ( Fig. 9 d).

Material Examined. Holotype and paratype, ANIC 404, litter, rainforest, Gogol Valley, 24 km west of Madang, Papua New Guinea, 5°12'13"S 145°34'53"E, 50 m., coll. R.W. Taylor, 20.vii.1972. Paratype, ANIC 378, litter, rainforest, near Popondetta, Papua New Guinea, 8°48'11"S 148°21'7"E, 50 m., coll. R.W. Taylor, 31.v.1972. Holotype and paratype deposited in the Australian National Insect Collection, CSIRO Ecosystem Sciences, Canberra.

Etymology. This species is named for its type locality in the Gogol Valley, near Madang, Astrolabe Bay, Papua New Guinea.

Remarks. Malaconothrus gogolensis sp. nov. differs from other members of the genus by the following combination of characters: 1) the very short setae ro, le and in; 2) the partial inter-rostral ridge; 3) the distance from c 1 to c 2 is 2.5 × that between c 2 to c 3; 4) the posterior notogastral ridges with the transverse double-curved ridge and curved anterior lateral ridges; 5) the short notogastral setae but with cp, h 2 and e 1 longer than the others;6) the rectangular notogastral shield with a caudal indentation; 7) the cerotegument of small, regular pits; 8) four pairs of long, flagelliform genital setae; 9) the epimeral setal formula 3-1-3-2; 10) the very long epimeral seta 1b.

Malaconothrus gogolensis sp. nov. shares morphological similarities with a group of Afrotropical, Neotropical, Oriental, Oceanic and Australasian species with very short interlamellar setae (less than twice length of ex), short notogastral setae, well-developed median longitudinal notogastral ridges meeting a posterior Mshaped ridge with a subsidiary curved ridge between setae p 1 and 4–6 pairs of genital setae, including M. asiaticus Aoki, 1967 ( Thailand) ; M. beecroftensis Colloff & Cameron, 2013 ( Australia) ; M. cordisetus Mahunka, 1993 ( Rwanda) ; M. cornutus Hammer, 1973 ( Western Samoa); M. ensifer Mahunka, 1982 ( Ethiopia, Congo); M. foliatus Aoki, 1994 ( Marianas Islands); M. keriensis Hammer, 1966 a ( New Zealand, Java); M. neoplumosus Balogh & Mahunka, 1969 ( Bolivia) ; M. stigmatus Yamamoto & Coetzee, 2003 ( South Africa); M. subrasus Balogh, 1964 ( Madagascar) and M. variosetosus Hammer, 1971 ( Fiji) . Of these, M. cordisetus , M. foliatus M. neoplumosus and M. variosetosus have barbed and/or phylliform notogastral setae, whereas in the others they are smooth. Of those with smooth notogastral setae, M. cornutus , M. keriensis , M. stigmatus and M. subrasus have well-developed, barbed rostral setae. Malaconothrus gogolensis is the only species with four pairs of genital setae and minute, smooth rostral setae on short tubercles. Also, the form of the notogastral ridges is quite different from the others, with the M-shaped ridge and subsidiary curved ridge between setae p 1 more pronouncedly curved than seen on other species and positioned more anteriorly.

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.