Porrhotegaeus githabul, Colloff, 2023

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 : 72-75

Porrhotegaeus githabul sp. nov.

( Figs. 36–38 )

Dimensions. Holotype male: length 1,019 μm, breadth 788 μm; paratype male: length 1,021 μm, breadth 790 μm; paratype females: length 1,098, 1,058 μm, breadth 814, 802 μm; paratype tritonymph: length 922 μm, breadth 704 μm; paratype deutonymph: length 581 μm, breadth 455 μm.

Description of adult. Prodorsum: rostrum acute, rounded; rostral setae (ro) short, straight, smooth. Lamellae broad, with fine striae, lateral margins strongly convex, serrated; cusps broadly separated medially, with a single apical tooth; lamellar setae (le) long, curved, with spinose ornamentation, originating on ventral surface of lamellar cusp close to margin of rostrum ( Fig. 36a ). Bothridia long, corniculate, extending beyond lateral margins of lamellae, with marked indentation anterior of bothridium; bothridial seta long, smooth, pointed.

Notogaster: ratio of length to breadth: 0.76; notogaster rounded, flat, smooth, without obvious cerotegument. Humeral process long, with striate microsculpture becoming reticulate basally, pointed, reflexed ventrally, serrated, lateral margin slightly concave basally; medial margins convex: incised and folded laterally at their bases ( Fig. 36a ). Lyrifissures ia and im not visible. With nine pairs of long, stout, setiform, marginal setae (with complete l, h and p series) bearing fine spines, projecting vertically; setae p 2 and p 3 shorter than l and h series, but not markedly so; setae p 1 positioned dorsally and same length as l and h series.

Ventral aspect: subcapitulum acute, narrow; subcapitular setae h extremely long, thin; a and m shorter. Chelicerae chelate-dentate and of normal proportions. Tutorium broad, curved, with sharp apex ( Fig. 36b ). Epimeral plates not discrete in midline, sub-rectangular to trapezoid, plates I and II large, plate I with medial incision, plates III and IV fused, much smaller than others; epimeral setation 3-1-3-2; setae very short, sub-equal in length except much longer 4c. Pedotectum I (pd I) well-developed, apex sub-rectangular pd II with longitudinal margin convex, inflated, posterior margin concave; pd I and pd II with reticulate microsculpture; discidium curved, blunt apically; and enantiophysis E4 present, perigenital carina absent. Ventral plate ovoid, broader than long. Genital and anal plates separated by distance of third of length of genital plates; genital plates 140 µm long, with six pairs of short setae sub-equal in length, g 5 displaced laterally; three pairs of long, thin adanal setae; lyrifissure iad in para-anal position, some distance from margin of anal plate, about same as length of iad. Anal plates lozenge-shaped, 183 µm long. Pre-anal organ (po) T-shaped.

Description of tritonymph, deutonymph and nymphal scalps. Tritonymph prodorsum: Rostrum acute; rostral setae with spinose ornamentation, on short tubercles adjacent to medial margin of lamellar cusps, extending well beyond cusps; lamellar setae long, curved medially, with spinose ornamentation, emerging from ventral surface of lamellar cusp close to margin of subcapitulum; anterolateral margin of lamellar cusps with small spinose projections, posterolateral margin smooth ( Fig. 37 ). Central prodorsum smooth, porose; setae in small, thick, spinose. Bothridia long, curved, tubular, projecting laterally well beyond prodorsal margin. Bothridial seta long, thin, bacilliform.

Tritonymph gastronotum: U-shaped, broader than long. Dorsosejugal scissure transverse, with short, smooth setae c 1 and c 2 on short tubercles. With 12 pairs of notogastral setae: setae c 3, the l and h series and p 1 long, straight, with spinose ornamentation, emerging from elongated apophyses of gastronotum and bear elongate lateral scales with strongly serrated margins and fine venation ( Fig. 37 ); setae p 2 and p 3 short, curved, positioned ventrally, p 2 with spinose ornamentation.

Tritonymph ventral aspect: microsculpture of ventral plate with small sparse tubercles ( Fig. 38a ); 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.

Deutonymph gastronotum: with 11 pairs of setae: complete c and l series, h 2 and h 3; h 1 absent; c 1 and c 2 short, smooth, others long, with spinose ornamentation, on long apophyses with lateral serrated scales ( Fig. 38a ); p series short smooth positioned ventrally; p 3 represented only by their alveoli ( Fig. 38b ).

Deutonymph ventral aspect: ventral plate smooth; epimeral setal formula 3-1-2-2; with three pairs of genital setae, one pair of aggenital setae, two pairs of adanal setae; anal setae absent ( Fig. 38b ).

Ontogenetic formula of gastronotic setae (including one larval and two protonymphal and deutonymphal setae not present on scalps):?-(11,11,12)-9.

Etymology. The specific name is a noun in apposition. The species is named for the Githabul People of the Kyogle, Woodenbong and Tenterfield areas of north-eastern New South Wales on whose traditional land the species occurs.

Type designation, material examined and locality data. holotype male, ANIC accession no. 53-1089 , paratypes: one male, two females, ANIC accession no. 53-1090, ANIC 775 , litter, closed forest, Richmond Range State Forest , New South Wales, 28°29’S 152°35’E, 600 m., coll. T. Weir and A. Calder, 13-14.ii.1983 . Paratype tritonymph, ANIC accession no. 53-1091, ANIC 655 A, litter, Nothofagus moorei rainforest, O’Reilly’s Rainforest Retreat, Lamington National Park , Queensland, 28°14'S, 153°08'E, 920 m., coll. J. Lawrence and T. Weir, 22- 27.xi.1978 . Paratype deutonymph, ANIC accession no. 53-1092, ANIC 459 , litter, Nothofagus moorei rainforest, O’Reilly’s Rainforest Retreat, Lamington National Park , Queensland, 28°14’S 153°08’E, 920 m, coll. R. W. Taylor, 21.iii.1973 .

Diagnosis. Porrhotegaeus githabul can be distinguished from other species in the genus by the following combination of characters: (1) the striate lamellae with serrated margins; (2) the lamellar cusp with a single tooth; (3) the marked indentation anterior of bothridium at the base of the lamella; (4) the humeral processes with serrated medial margins; (5) the long notogastral setae p 2 and p 3; at least half the length of p 1; (6) the relatively small pedotectum II, not projecting markedly beyond the margin of the ventral plate; (7) the very long, smooth epimeral setae 4c; (8) the curved, pointed discidium with a blunt apex.

Remarks. Porrhotegaeus githabul is morphologically most similar to P. ornatus in having striated lamellae, a single apical tooth on the lamellar cusp and long setae p 2 and p 3. However, in P. ornatus pedotectum II is large and rectangular, the lamellae reticulate, the lamellar setae smooth and the lateral margins of the tutoria serrated. Also, the discidium of P. githabul is curved, not straight, the anterior condyles of enantiophyses B and the perigenital carinae are absent, the lateral margins of the lamellae are toothed, not smooth, and the medial margin of the lamellar cusp is convex, not concave.

The association of the tritonymph and deutonymph with the adult is based, in part, on their presence in the same samples. Adults of P. githabul and P. ornatus occur at Lamington National Park where the tritonymph and deutonymph of the former species were also found and it is possible they belong to P. ornatus . However, the tritonymph in Fig. 38 shares with the adults of P. githabul the sharply pointed lamellar cusps with strongly toothed borders and convex medial and lateral margins. The morphology of the lamellae is quite different from those of the adults of P. ornatus .

A tritonymph of a Porrhotegaeus sp. , from Lamington National Park is illustrated in the poster, Mites of the Rainforest (Walter et al., n.d.) and by Walter (2004, p. 230). The morphology of the lamellae is different from the tritonymph of P. githabul , being broader, in a more posterior position on the prodorsum and the margins have short, sparse serrations. It is probable the illustrations are of the tritonymph of P. ornatus .

Figures

FIGURE 36. Porrhotegaeus githabul sp. nov., adult (a) dorsal aspect; (b) ventral aspect. Scale bar = 200 μm.

FIGURE 37. Porrhotegaeus githabul sp. nov.: tritonymph with deutonymphal scalp, dorsal aspect. Scale bar = 200 μm.

FIGURE 38. Porrhotegaeus githabul sp. nov. (a) tritonymph, ventral aspect; (b) deutonymph, ventral aspect. Scale bar = 200 μm.