Retrozetes mirabilis, Colloff, Matthew J., 2012

Colloff, Matthew J., 2012, New eremaeozetid mites (Acari: Oribatida: Eremaeozetoidea) from the south-western Pacific region and the taxonomic status of the Eremaeozetidae and Idiozetidae, Zootaxa 3435, pp. 1-39 : 22-23

Retrozetes mirabilis sp. nov.

( Fig. 14 )

Dimensions. Holotype female length 252 μm, breadth 218 μm. Ratio of prodorsum to total length: 0.46. Female. Cerotegument: reticulate or amorphous; lightly covering prodorsum, notogaster and ventral surface; oval centrodorsal region bare ( Fig. 14 a).

Prodorsum: Lamellae broad, lateral margins parallel, extending beyond margins of bothridia; fused posteriomedially, smooth, separated along anterior quarter by narrow slit ( Fig. 14 a). Lamellar cuspides strongly curved ventrally, apices rectangular, converging medially ( Fig. 14 b). Posteriolateral lamellar margin diagonal, concave ( Fig. 14 a). Rostral seta (ro) thin, curved, short (8 μm long) on squat tubercles. Lamellar seta (le) spiniform, 18 μm long, emerging from alveolus on medial margin of lamellar cusp, pointing anteriomedially, apices crossing. Interlamellar setae thin, minute (5 μm long), close together on thin transbothridial ridge. Bothridial seta 70 μm long; head narrow, expanding and slightly barbed apically. Bothridium cup-shaped, opening narrow, enclosed; rim not undulating.

Notogaster: Length 130 μm; ratio of length to breadth 0.83; notogaster broad, oval, broadest at level between setae la and lp; pteromorphs projecting. Dorsosejugal suture transverse ( Fig. 14 a). Dorsosejugal lobe a short, broad projection bearing apophysis of seta c 2. Lenticulus immediately posterior of dorsosejugal suture, 27 μm long, 24 μm broad, oval; margin a U-shaped ridge. Notogastral cuticle smooth. Ten pairs of smooth, short (6-15 μm), thin, curved setae on broad, well-developed tubercles. Setae lm positioned medially, close together. Lyrifissurae im and ih on lateral margin of notogaster, not visible in dorsal view; saccule (sa) anterior of lp. Caudal region of notogaster rounded; tubercles of h series not projecting beyond margin; p series positioned ventrally.

Subcapitulum: Mentum U-shaped, convex, smooth, 1.1 × as long as broad; anterior margin not reflexed ( Fig. 14 b). Seta h and m sub-equal in length (5 μm).

Coxisternum: Epimeral setae setiform, of variable length (5–12 μm long); 1b longer than others; formula 2-1- 2-1 ( Fig. 14 b). Genital and anal plates almost adjacent. Genital plates sub-hexagonal, smooth; each plate 48 μm long, 21 μm broad, with six spiniform setae sub-equal in length, aligned longitudinally. Aggenital seta setiform, 5 μm long, positioned posteriolateral of genital plate. Ventral plate smooth.

Anogenital Region: Anal plates sub-hexagonal ( Fig. 14 b); each anal plate 34 μm long, 22 μm broad, smooth, with faint median carina. Anal setae 6 μm long, thin, emerging from alveoli ( Fig. 14 b). Adanal setae setiform, thin, ad 1 positioned on squat tubercle on ridge immediately posterior of anal plates; ad 2-3 positioned laterally, close together; distance between ad 1 and ad 2 2.5 × mutual distance between ad 1.

Lateral aspect: Rostrum slightly curved, projecting vertically ( Fig. 14 c). Rostral seta, spiniform, on squat tubercle posterior of apex of rostrum. Tutorium narrow, lath-like, projecting anteriorly; apex acute. Lamellar cuspides curved anterioventrally, strongly reflexed posteriorly then ventrally, pointed apically; projecting well above prodorsum and separated for almost their entire length. Lamellar setae positioned dorsally, near anteriormost point of lamella, some distance posterior of lamellar cusp. Pedotectum I smooth, curved, lacking tooth. Interbothridial region flat. Lenticulus flattened, projecting just above dorsal surface, notogaster concave posteriorly. Dorsosejugal lobe extending to bothridium. Pteromorph smooth, triangular, extending to ventral surface, 62 μm long, 33 μm broad basally; anterior margin slightly convex; posterior margin straight or slightly concave. Centrodorsal region of notogaster slightly convex from anterior of lp to position level with seta h 2; lateral margin of notogaster between h series and circumgastric scissure wedge-shaped, broadest posteriorly; caudal margin concave; setae lp and h series on bulbous tubercles.

Legs: Pretarsi monodactylous.

Material examined. Holotype, ANIC 585, leaf litter, rainforest, Dumbea, New Caledonia, 22°05'S 166°27'E, 650 m., coll. P. Ward, 25.ii.1977. Holotype deposited in the Australian National Insect Collection, CSIRO Ecosystem Sciences, Canberra.

Etymology. This species name is from the Latin adjective mirabilis , meaning wonderful, marvellous, extraordinary.

Remarks. Retrozetes mirabilis differs from other species in the genus by the following combination of characters: 1) the broad, rectangular lamellar cuspides; 2) the narrow, slit-like lamellar fissure; 3) the lamellar cuspides curved anterioventrally, strongly reflexed posteriorly then ventrally in lateral view, 4) the undulating lateral margins of the lamellae; 5) the long, apically expanded bothridial seta with apical barbs; 6) the rounded notogaster, broader than long; 7) the genital and anal plates almost adjacent.

Retrozetes mirabilis is morphologically most similar to R. koghisensis (cf. above).

Figures

FIGURE 14. Retrozetes mirabilis sp. nov., holotype female, cerotegument removed; a) dorsal b) ventral; c) lateral aspect.