Malaconothrus jowettae, Colloff, Matthew J. & Cameron, Stephen L., 2013

Colloff, Matthew J. & Cameron, Stephen L., 2013, A phylogenetic analysis and taxonomic revision of the oribatid mite family Malaconothridae (Acari: Oribatida), with new species of Tyrphonothrus and Malaconothrus from Australia, Zootaxa 3681 (4), pp. 301-346 : 327-330

Malaconothrus jowettae sp. nov.

( Figs. 17 , 18 )

Dimensions. Holotype female length 454 μm, breadth 221 μm. Paratype female length 451 μm, breadth 217 μm. Ratio of prodorsum to total length: 0.26 (holotype).

Female. Prodorsum. Rostrum broad, rounded. Rostral seta (ro) smooth, setiform, 29 μm long, longer than mutual distance, on apex of simple, curved lateral carina ( Fig. 17 a). Lamellar seta (le) smooth, setiform, 27 μm long, shorter than mutual distance, extending anteriorly beyond base of seta ro. Interlamellar seta (in) smooth, thin, setiform, 64 μm long, shorter than distance between them. Exobothridial seta ex 1 smooth, 27 μm long. Prodorsum smooth, porose. Cerotegument densely granular.

Notogaster. Dorsosejugal furrow transverse; humeral region rounded ( Fig. 17 a). Cerotegument of small alveoli. Lyrifissure ia 16 μm long. With 15 pairs of thin, smooth setae; e 2, h 1 and h 2 51–67 μm, others 24–42 μm. Seta c 2 equidistant between c 1 and c 3. Posterior notogaster with faint, lateral concavities; margin not indented at level of seta h 2; ridge absent 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. 17 b, c). Notogaster relatively narrow, elongated, shield-shaped; margins parallel, broadest at level of e 2. Ratio of length to breadth 1.49. Caudal margin broadly V-shaped. Lyrifissurae ip curved, transverse.

Coxisternum. Epimeral setal formula 3-1-3-3 ( Fig. 17 b); setae smooth, setiform; 1b, 3b, 3c, 4b and 4c 15-25 μm long, others 4-9 μm; 1c and 4b in posteriolateral position, 3b in median position. Epimeral plates all separated medially. Posteriolateral margins of epimeral plates II rounded. Apodeme IV concave, wedge-shaped.

Anogenital Region. With five pairs of long, thin, smooth, flagelliform genital setae directed posteriorly ( Fig. 17 b); g 1 short (20 μm), g 2-3 longer (35 μm) g 4-5 longest (52 μm). Most setae longer than width of genital plate. Genital plates sub-hexagonal; each plate 82 μm long, 36 μm broad; posterior margin slightly angled acutely. One pair of long (16 μm) setiform anal setae, four times width of anal plate. Each adanal plate 82 μm long, 22 μm broad; three pairs of long (40–52 μm) thin, smooth, flagelliform adanal setae, longer than width of adanal plate. 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; undulating between le and in ( Fig. 17 c). Seta le projecting anterior of base of seta ro. Seta ex 1 projecting posteriolaterally; seta ex 2 represented by alveolus. Pedotectum I well-developed, semi-circular. Hysterosoma strongly dorsoventrally flattened. Notaspis flat between setae c 1 and e 1, then curved; slight concavity anterior of p 1: ratio of height to length 0.38. Pleuraspis without humeral process.

Legs. Pre-tarsi I and II heterotridactylous; lateral claws sparingly barbed on dorsal edge; claws on legs III and IV smooth ( Fig. 18 ). Legs short and broad: Leg I 154 μm long; tarsi sub-conical. Ratio of length to breadth of Tarsi: I 1.9; II 1.94; III 2.65; IV 3.02. Setal formula: Leg I 1-4 -2(1)-4(1)-11(3); Leg II 1-5 -2(1)-4(1)-10(1); Leg III 2-3 -1- 2(1)-10; Leg IV 1-2 -1-2-10. All setae smooth except barbed seta d on femur IV. Tarsus I with proral setae (p) markedly thinner than unguinal setae (u), pointed ( Fig. 18 a); p short, blunt, broad on other tarsi, similar to unguinal setae; solenidia ω2-3 positioned anteriorly: separated from ω1; famulus (ε) minute, conical (5 μm); fastigial setae (ft) homeomorphic: long, pointed, ft ’ slightly longer than ft ”. Tarsus II and III with setae ft as for Tarsus I ( Fig. 18 b, c).

Trochanter III with very long seta v 2; Trochanter IV with seta v. Tarsus IV with ft ” long, straight, pointed; seta s same shape but slightly longer than primiventral setae (pv) ( Fig. 18 d).

Material examined. Holotype female and paratype female, ANIC 3507, trough of flight intercept trap, Maurge Jowett’s garden, Red Road, Norfolk Island, 29°0'37.73"S, 167°56'43.49"E, ca. 250 m., coll. M. Christian & M. Sexton, 8.iii.1985. Holotype and paratype deposited in the Australian National Insect Collection, CSIRO Ecosystem Sciences, Canberra.

Etymology. This species is named in honour of Mrs Maurge Jowett in recognition of her contribution to the conservation of the biota of Norfolk Island.

Remarks. Malaconothrus jowettae sp. nov. differs from other members of the genus by the following combination of characters: 1) setae ro and le are subequal in length; 2) setae c 1 and c 3 are at least twice the length of c 2; 3) notogastral ridges are absent; 4) setae e 2, h 1 and h 2 are longer than the other notogastral setae; 5) the notogaster is shield-shaped and slightly pointed caudally; 6) 3b, 3c and 4c are the longest of the epimeral setae; 7) apodeme IV is wedge shaped; 8) the five pairs of very long, flagelliform genital setae; 9) seta ad 3 is extremely long and flagelliform.

Malaconothrus jowettae is one of a group of species that includes M. crispus ( Hammer, 1966) , M. elegans ( Hammer, 1966) , M. longisetosus ( Yamamoto & Aoki, 2000) , M. tardus ( Michael, 1888) , M. almagrensis Iglesias, Palacios-Vargas & Mahunka, 2001 and M. knuellei sp. nov. They share the lack of notogastral ridges, the dense, alveolate cerotegument, the fine, smooth, sometimes flagelliform idiosomal setae; the five pairs of flagelliform genital setae and setae e 2, h 1 and h 2 longer than the other notogastral setae. Malaconothrus crispus and M. elegans have much shorter mediodorsal setae; M. longisetosus has very long setae h 3, p 2 and p 3; M. tardus has a diagonal ridge between h 1 and h 2; M. almagrensis has a pointed rostrum and shield-shaped notogaster. Malaconothrus jowettae is morphologically most closely related to M. knuellei (cf. below).

Figures

FIGURE 17. Malaconothrus jowettae sp. nov., holotype female; a) dorsal; b) ventral; c) lateral.

FIGURE 18. Malaconothrus jowettae sp. nov., left legs, antiaxial view; a) Leg I; b) Leg II; c) Leg III; d) Leg IV.