Eutegaeus odontatus, 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 : 25-27

Eutegaeus odontatus sp. nov.

( Fig. 10 )

Dimensions. Holotype female length 843 μm, breadth 586 μm. Paratype females (n = 3): mean length 850 μm (range 837–861 μm); mean breadth 619 μm (range 608–639 μm). Paratype males: lengths 790, 805 μm, breadths 568, 576 μm. Ratio of prodorsum to total length: 0.36 (holotype).

Description of adult. Prodorsum: rostrum acute; rostral setae (ro) setiform, curved, smooth, visible in dorsal aspect. Lamellae very broad apically, separated medially, with reticulate microsculpture, lateral margins conspicuously convex and heavily sclerotised, incurved basally, with partial translamella. Lamellar setae (le) very long, smooth, flagelliform, overlapping, emerging from cup-shaped incisions of broad lamellar cusp, each flanked laterally and medially by sharp tooth; cusps extending to same level as apex of rostrum, medial margins of lamellae concave; lateral margins heavily sclerotised; partial translamella present ( Fig. 10a ). Interlamellar setae (in) very long, setiform, smooth, extending beyond rostrum, positioned close together on central prodorsum on faint, inverted Vshaped ridge. Posterior prodorsum with anterior condyles of enantiophyses B. Bothridia projecting laterally beyond median margins of humeral processes, marked invagination at base of lamella; bothridia with peg-like anterior projection and bilobed anterior condyle of enantiophysis H on posterior margin. Bothridial seta short, extending just beyond lateral margin of humeral process, curved, with narrow, slightly expanded head with fine spines.

Notogaster: with thin cerotegument covering sinuous microsculpture ( Fig. 10a ); ratio of length to breadth: 0.87; notogaster rounded, convex. Humeral processes broad, without dorsal keel; waisted at their bases laterally, with a pronounced apical tooth, extending to point level with base of lamellar cusps. Short, sub-triangular projection on notogaster posterior of humeral process; lyrifissure ia not visible. With eight pairs of notogastral setae: l series, h 2 and h 3 curved, smooth relatively long: about same length as setae in; setae la and lm in centrodorsal position, all others sub-marginal ( Fig. 10a ); setae of p series short, sub-equal in length; p 1 on small flat tubercles. Lyrifissures im not visible.

Ventral aspect: subcapitulum broad; mentum about same breadth as length; subcapitular setae smooth, h sub-equal in length to a and m ( Fig. 10b ). Tutorium short, blunt, not visible in ventral aspect. Median margins of epimeral plates absent; plates sub-rectangular to sub-triangular, II and III about the same dimensions; epimeral setation 3-1-3- 2; seta 4c markedly longer than 4b. Pedotectum I (pd I) well-developed, sub-rectangular; pd II curved, horn-shaped; discidium triangular, with sharp point. Ventral plate broader than long, with slight invagination posterior of anal plate. Genital and anal plates separated by distance slightly less than length of genital plates; genital plates 94 µm long, with six pairs of setae, all aligned longitudinally, g 1 slightly longer than others; lyrifissure iad in para-anal position, close to margin of anal plate, same distance as its length. Anal plates lozenge-shaped, 171 µm long. Pre-anal organ (po) T-shaped.

Type designation, material examined and locality data. Holotype female, ANIC accession no. 53-1042; paratypes: three females, two males, ANIC accession no. 53-1043, ANIC 107 , moist upland hardwood forest (cf. Invasive Species Council and TierraMar, 2021 for description), Mount Pitt , Norfolk Island, 29°1’S, 167°56’E, 230 m, coll. M.S. Upton, 12.vii.1968.

Etymology. The specific name is derived from the Greek ὀδούς (odonts) meaning a tooth, referring to the tooth at the apex of the humeral process.

Diagnosis. Eutegaeus odontatus can be distinguished from other species in the genus by the following combination of characters: (1) the long, thin, flagelliform lamellar setae; (2) the very broad lamellae, expanded apically; (3) the heavily sclerotised lateral margins of the lamellae; (4) the concave margins of the lamellar cusps; (5) the extremely long setae in; (6) the short bothridial seta with a slightly expanded head and fine spines; (7) the prominent bi-lobed anterior condyle of enantiophysis H; (8) the stepped, peg-like anterior projection of the bothridium; (9) the presence of anterior condyles of enantiophysis B; (10) the long notogastral setae of the l and h series, with la and lm located centrodorsally and lp and the h series located sub-marginally; (11) setae p 1 located on squat tubercles; (12) the genital setae all aligned longitudinally; (14) the invagination posterior of the anal plate.

Remarks. Eutegaeus odontatus shares with E. woiwurrung , E. membraniger and E. curviseta the short setae of the p series, with p 1 on squat tubercles, and with these species and E. nothofagi the lamellar cusps with a pair of well-developed teeth. Like E. nothofagi the species has the anterior condyles of enantiophysis B and, like this species, E. woiwurrung and E. soror , a prominent sub-triangular projection at the base of the humeral process, as well as notogastral setae la and lm in the centrodorsal position and lp and the h series in the sub-marginal position. Eutegaeus odontatus and E. woiwurrung both have a partial translamella but E. odontatus differs from E. woiwurrung and E. nothofagi in that the lamellar setae, interlamellar setae, notogastral setae of the l and h series and setae 4c are much longer, the bothridial setae are much shorter, with slightly expanded heads covered with spinules and the humeral process lacks a dorsal keel.

Figures

FIGURE 10. Eutegaeus odontatus sp. nov., adult (a) dorsal aspect; (b) ventral aspect. Scale bar = 200 μm.