Atalotegaeus mensarosi (Balogh & P. Balogh, 1983)

Colloff, Matthew J., 2023, The oribatid mite superfamily Eutegaeoidea (Acari, Oribatida), with descriptions of new taxa from Australia and New Caledonia and a re-assessment of genera and families, Zootaxa 5365 (1), pp. 1-93 : 35-37

Atalotegaeus mensarosi (J. & P. Balogh, 1983)

( Figs. 15 , 16 )

Eutegaeus mensarosi J. & P. Balogh, 1983a, p. 82 .

Atalotegaeus mensarosi (J. & P. Balogh, 1983): Luxton, 1988a, p. 83.

Dimensions. Holotype male: length 577 μm, breadth 423 μm. Ratio of prodorsum to total length: 0.43. Non-type material: females (n = 5) mean length 611 (range 596–632) mean breadth 417 (range 395–435). Tritonymph: length 530 μm, breadth 394 μm.

Redescription of adult. Prodorsum: rostrum markedly acute; rostral setae (ro) long, recurved, smooth, visible in dorsal aspect. Lamellae broad, separated medially, lateral margins convex, extending beyond lateral margin of prodorsum, with microsculpture of scale-like plaques; translamella absent ( Fig. 15a ). Lamellar seta (le) smooth, long, flagelliform, emerging sub-apically on lateral edge of lamella; lamellar cusp with single tooth, extending just beyond rostrum. Interlamellar setae (in) extremely long (258 μm), smooth, flagelliform, emerging on posteromedian of prodorsum. Bothridia relatively short, angled laterally, projecting at least to inner margin of humeral processes, openings with small apical flange on lip. Bothridial setae very long, curved, bacilliform, smooth.

Notogaster: ratio of length to breadth: 0.82; notogaster rounded, convex. Humeral processes extending anteriorly to point level with third of lamellar length, narrow, waisted at base then expanded, with pointed apex, convex lateral margin, V-shaped projection at base ( Fig. 15a ). With eight pairs of notogastral setae; l, h 2 and h 3 and p series present, setae of l and h series long, curved, smooth, setae la and lm in centrodorsal position, others sub-marginal, setae lp markedly longer than others of l and h series (240 μm); p series markedly shorter than l and h series (47 μm).

Ventral aspect: subcapitulum narrow, acute apically, mentum much longer than broad; subcapitular setae short, smooth, sub-equal in length ( Fig. 15b ). Long, thin rutellum protruding beyond rostrum ( Fig. 15c ). Chelicerae thin, narrow but chelate-dentate apically, protruding beyond apex of subcapitulum. Tutorium short, rounded apically, not visible in ventral aspect. Epimeral plates discrete, all broadly separated in midline, sub-rectangular to sub-triangular, plates IV shorter than others; epimeral setation 3-1-3-2; setae 3c and 4b longer than others. Pedotectum I (pd I) well-developed, curved, pointed; pd II small, pointed; discidium sub-rectangular, bicornute. Ventral plate broader than long. Genital and anal plates close together; genital plates 70 µm long, with six pairs of setae, sub-equal in length, g 4 displaced laterally; lyrifissure iad in para-anal position, some distance from anal plate, more than length of iad. Anal plates lozenge-shaped, 98 µm long; setae of the ad series long, setiform, thin, similar length to setae p 1. Pre-anal organ (po) T-shaped.

Description of tritonymph, nymphal and larval scalps. Tritonymph prodorsum: with well-developed cerotegument of small columnar cells along prodorsal margins ( Fig. 16a ). Rostrum acute; rostral setae smooth, on short tubercles, extending beyond lamellar cusps; lamellar setae long, curved medially, with plumose cerotegument, emerging from short tubercle at base of lateral margin of lamellar cusp; cusps with small scattered tubercles, each cusp with prominent incurved tooth almost meeting opposing tooth. Lateral margin of lamella incised transversely posterior of seta le and again anterior of bothridium; central prodorsum with alveolate microsculpture. Setae in with leaf-shaped cerotegument, emerging from short tubercles. Bothridia long, cup-shaped, constricted basally, with prominent apical flange; bothridial seta long (210 µm), thin, straight, slightly expanded apically, with pointed tip.

Tritonymph gastronotum: U-shaped, broader (394 µm) than long (362 µm). Anterolateral margin with humeral process rounded anteriorly and bearing seta c 3, then incised posteriorly. Gastronotal setae emerging from well-developed tubercles ( Fig. 16a ). With 12 pairs of setae: full complement of c, l, h and p series present; c 3, l and h series and p 1 with broad, paddle-shaped cerotegumental covering, each with few spines basally; seta c 1 setiform, smooth; c

2 short, spinose.

Deutonymphal and protonymphal scalp: with eight pairs of setae: c 1 (c 2 and c 3 absent), l series and h 2, h 3 and p 1, all on short tubercles except c 1; deutonymphal scalp ( Fig. 16a )

Larval scalp: with alveolate microsculpture; eight pairs of setae with leaf-like cerotegument, on short tubercles: l series, h 2 and h 3, p 1 and centrodorsal series d present. Setae dp on small ovoid sclerite ( Fig. 16a ).

Tritonymph ventral aspect: microsculpture of ventral plate with fine striations ( Fig. 16b ); anal plate with fine tubercles; epimeral setal formula 3-1-3-3; with four pairs of genital setae, one pair of aggenital setae, two pairs of anal setae and three pairs of adanal setae.

Ontogenetic formula of gastronotic setae (including one larval and two protonymphal and deutonymphal setae not present on scalps): 9-(10,10,12)-8.

Material examined and locality data. Holotype, ANIC accession no. 53-637, litter, Nothofagus moorei rainforest, Point Lookout, near Ebor , New South Wales, 30°29’S, 152°25’E, 1525 m, coll. I. Naumann, 25.iv.1973 . Non-type material: five females, ANIC 460 , litter, Nothofagus moorei rainforest, O’Reilly’s Rainforest Retreat, Lamington National Park , Queensland, 28°14'S, 153°08'E, 920 m., coll. R. J. Kohout, 21.iii.1973 .

Diagnosis. Atalotegaeus mensarosi can be distinguished from the other species in the genus by the following combination of characters: (1) the elongated mentum; (2) the slim, fine chelicerae; (3) the lamellae with reticulate microsculpture; (4) the very long interlamellar setae (5) the long adanal setae; (6) the setae p 1 markedly longer than setae p 2 and p 3; (7) the very long epimeral setae 3c and 4c and (8) the small apical flange on the bothridium.

Remarks. Atalotegaeus mensarosi is morphologically most similar to A. crobylus , as detailed above.The nymphs of this species lack the intricate scales associated with the lateral gastronotal setae of the nymphs of Eutegaeus spp. described herein. The association of the tritonymph with the adult is based, in part, on their presence in the same samples, but also the presence of the long, pointed, incurved lamellar cusp with the lamellar seta positioned sub-apically, similar to the morphology of the lamellar cusp in the adult.

The tritonymph of this species has the epimeral setal formula 3-1-3-3, but in the adult, it is 3-1-3-2 (as in A. crobylus and A. deficiens ), with seta 4b absent in the adult. The seta is present in the adults of the other species of Atalotegaeus . The loss of 4b in the adult also occurs in some species of Eutegaeus (cf. remarks section for E. woiwurrung above).

Figures

FIGURE 15. Atalotegaeus mensarosi (J. & P. Balogh, 1983), adult (a) dorsal aspect; (b) ventral aspect; (c) apex of rutellum. Scale bar (a, b): = 200 μm.

FIGURE 16. Atalotegaeus mensarosi (J. & P. Balogh, 1983), tritonymph, (a) dorsal aspect with larval and nymphal scalps; (b) ventral aspect. Scale bar = 200 μm.