Neoeutegaeus corniculatus, 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 : 50-51

Neoeutegaeus corniculatus sp. nov.

( Fig. 25 )

Dimensions. Holotype male length 275 μm, breadth 180 μm. Paratype males (n = 4) mean length 280 μm (range 275–287 μm), mean breadth 181 μm (range 176–183 μm). Paratype females (n = 8) mean length 292 μm (range 283–300 μm), mean breadth 190 μm (range 187–193 μm). Ratio of prodorsum to total length: 0.46 (holotype)

Description of adult. Prodorsum: rostrum truncated apically; rostral setae (ro) extremely short, smooth, not visible in dorsal aspect. Lamellae broad, very long, almost half length of body, extending well beyond rostrum, separated medially, lateral margins convex ( Fig. 25a ). Lamellar seta (le) very short, smooth, emerging from alveolus on anterior margin of lamellar cusp; medial margins of cusps convex, almost meeting in mid-line, with partial translamella; lamella with small pointed cusp just anterior of bothridium. Interlamellar setae (in) minute, broadly separated. Bothridia elongate, corniculate, projecting laterally beyond inner margins of humeral processes, angled anterolaterally, posterior margin of opening with curved projection. Bothridial seta long, head club-shaped, broad, with fine spines.

Notogaster: ratio of length to breadth: 0.77; notogaster rounded, convex. Humeral processes very long, as long as lamellae, straight, parallel, triangular, with dorsal keel, extending to point level with translamella; lateral margin expanded where process joins anterolateral margin of notogaster ( Fig. 25a ). Lyrifissures ia and im not observed. With eight pairs of notogastral setae, l series and h 2 and h 3 sub-marginal, smooth, curved, relatively short, sub-equal in length, stout, covered in cerotegument, rounded apically; p series very short, setiform, not visible in dorsal aspect. Cerotegument of coarse granules.

Ventral aspect: subcapitulum as broad as long; subcapitular setae short, sub-equal in length, smooth ( Fig. 25b ). Tutoria prominent, stout, curved, pointed, projecting well beyond lateral margins of prodorsum. Epimeral plates discrete, broadly separated in midline, sub-rectangular to ovoid, plates III and IV much shorter than I and II; with median strip of dumbbell-shaped cuticle between plates I and II, plates IV the smallest, ovoid; pair of epimeral foveolae (ef) present between plates II and III. Epimeral setation 3-1-2-2; setae very short, sub-equal in length. Pedotectum I (pd I) well-developed, rectangular, with blunt anterior apex; pd II long, broad, lateral margin sloped obliquely, indented; discidium broad, rounded; perigenital carina and enantiophysis E4 present. Ventral plate ovoid, markedly broader than long. Genital and anal plates separated by distance of half length of genital plates; genital plates 31 µm long, with five pairs of short, spinose setae sub-equal in length, g 4 displaced laterally; two pairs of short adanal setae; lyrifissure iad long, in para-anal position, some distance from margin of anal plate, about same as length of seta ad 2. Anal plates ovoid, 38 µm long. Pre-anal organ (po) oval.

Type designation, material examined and locality data. Holotype male, ANIC accession no. 53-1067, paratypes: four males, eight females, ANIC accession no. 53-1068, litter, Nothofagus cunninghami rainforest, Triplet Falls, Great Otway National Park , Victoria, 38°40’S, 143°30’E, coll. M.J. Colloff, 17.vii.2011.

Etymology. This specific name, corniculatus , is a Latin diminutive for ‘with horn-shaped projections’, referring to the prominent tutoria projecting from the lateral margins of the prodorsum.

Diagnosis. Neoeutegaeus corniculatus can be distinguished from other species in the genus by the following combination of characters: (1) the small pointed cusp on the lateral margin of the lamellar just anterior of the bothridium; (2) the prominent horn-shaped tutoria; (3) the incomplete translamella; (4) the posterior margin of the bothridial opening with a curved projection; (5) the minute interlamellar setae, broadly separated; (6) the presence of epimeral foveolae between epimeral plates II and III.

Remarks. Neoeutegaeus corniculatus shares with N. phyllophorus the pointed lamellar cusps, each with a single, short tooth positioned medially, the club-shaped heads of the bothridial setae with spinose ornamentation, the cusp anterior of the bothridium at the base of the lamella, the keeled humeral processes and the presence of epimeral foveolae. However, N. corniculatus has very short and smooth lamellar setae, not long barbed ones; the notogastral setae are blunt apically due to the covering of cerotegument, not pointed and it lacks the anterior condyle of enantiophyses H on the posterior prodorsum.

Figures

FIGURE 25. Neoeutegaeus corniculatus sp. nov., holotype male (a) dorsal aspect; (b) ventral aspect. Scale bar = 100 μm.