Eutegaeidae J. Balogh, 1965

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 : 12-13

Eutegaeidae J. Balogh, 1965

Eutegaeidae J. Balogh, 1965, p. 59 .

Type genus: Eutegaeus Berlese, 1916, p. 62 .

Diagnosis. the following diagnosis is modified from those of J. Balogh (1965), Woolley (1965) and Luxton (1988a). Rostrum acute, entire; lamellae very broad, covering lateral margins of prodorsum, with free cusps; lamellar seta emerging from excavation at apex of cusp, often between two teeth. Interlamellar setae positioned medial of bothridia; bothridium not fused with bases of lamellae, long, corniculate, opening anterolaterally, often with anterior condyle of enantiophysis H on posterior margin. Bothridial seta typically very long, setiform or bacilliform. Prodorsum waisted posterior of bothridium. Humeral processes prominent, ovoid, waisted basally, pointed apically, extending from anterolateral margin of notogaster to point at least halfway along length of lamella, but not reflexed ventrally. Notogaster circular to ovoid, convex, smooth, broader than long. With eight or nine pairs of notogastral setae, either all setae of the l and h series in the centrodorsal position ( Neseutegaeus ) or at least one pair in the l series in centrodorsal position ( Eutegaeus and Atalotegaeus ); setae of l and h series (and occasionally p 1) longer and of different morphology from those of p series (or p 2 and p 3). Chelicerae chelate-dentate and of normal proportions or slim but not with needle-like modified digits. Pedotectum I (pd I) sub-rectangular in lateral outline; pd II triangular or rectangular; discidium pointed. Circumpedal carina present. Perigenital carinae and enantiophyses E4 absent. Five or six pairs of genital setae, three pairs of adanal setae. Anal plates lozenge-shaped. Pre-anal organ T-shaped. Nymphs with or without one or most gastronotic setae emerging from flat scales; lateral margin of lamellar region strongly incised.

Remarks. Since the publication by J. Balogh (1965), the Eutegaeidae has contained between two and nine genera ( Table 1 ). The diagnosis above is based on a concept of the Eutegaeidae as containing only three genera ( Table 2 ): Eutegaeus , Atalotegaeus and Neseutegaeus , due to Birotegaeus and Pareutegaeus being newly synonymised with Eutegaeus , as detailed below.

The main character states that differentiate Eutegaeidae from the other families of Eutegaeoidea are the long, pointed humeral processes that emerge from the anterolateral margin of the notogaster, directly posterior of the bothridia and have a narrow, waisted point of attachment to the notogaster; narrower than the anterior part of the humeral process and one or more of the setae of the l series in the centrodorsal position. These two character states are synapomorphies of Eutegaeidae . In Neoeutegaeidae fam. nov. (cf. below) the humeral process also emerges on the anterior notogaster but its base is broad and has a distinct bulge and incurve where it meets the notogaster. In Compactozetidae the humeral process has its origin some distance posterior of that in Eutegaeidae and Neoeutegaeidae fam. nov., at the widest part of the notogaster. In Pterozetidae and Porrhotegaeidae fam. nov. the humeral process also originates in this position and is pointed apically and broad basally; its lateral margin is straight and lacks any prominent constriction or bulge at its base. In Bornebuschiidae fam nov. (cf. below) the humeral process also originates in this posterior position but it is rounded apically and does not extend anteriorly beyond the bothridium. In Cerocepheidae the humeral process is reduced to a short, triangular structure.

The lamellae of Eutegaeidae , Cerocepheidae and Neoeutegaeidae fam. nov. and Porrhotegaeidae fam. nov. have free cusps and are broad, not apically convergent, with convex or straight lateral margins and the lamellar seta emerges from an excavation at the apex of the cusp, typically between two teeth, or the cusp is incurved and the lamellar seta emerge sub-apically ( Atalotegaeus ). In Compactozetidae the lamellae are fused with each other apically and curved ventrally and fused with the rostrum in Compactozetes or are slightly convergent apically and have a rounded or obliquely-angled free cusp ( Sadocepheus , Hamotegeus ). In Pterozetidae the lamellae are fused with each other apically but not folded ventrally. In Bornebuschiidae fam nov. the lamellar seta is positioned some distance posterolaterally, at the base of the lamellar cusp, which is either curved and blunt ( Bornebuschia ) or very long and pointed, extending well beyond the rostrum ( Dicrotegaeus ). In Porrhotegaeidae fam. nov. the lamellae are similar to those of Eutegaeidae , but the lamellar seta emerges from the ventral surface of the lamellar cusp.

The margins of the coxisternum, comprising pedotecta I and II and the discidium, are relatively uniform in morphology in Eutegaeidae and Cerocepheidae when viewed ventrally. The morphology of these structures in ventral aspect does not fully reveal their three-dimensional shape, which becomes more apparent in lateral aspect (compare Figs. 27b and 27c ) but, as mentioned in the methods section above, lateral aspects were not illustrated because of the difficulty in making temporary mounts of specimens in which the hysterosoma is broader than long. However, the ventral aspects of these structures ( Fig. 44 ) reveals useful similarities and differences between taxa. Pedoctectum I is sub-rectangular in all genera of Eutegaeidae and Cerocepheidae and the anterior margin is transverse or oblique. Pedotectum II is pointed and triangular/rectangular in Atalotegaeus and Cerocepheus , in those species of Eutegaeus for which the ventral surface has been described and in Neseutegaeus . The discidium is thin, triangular and pointed in Cerocepheidae and all species of Eutegaeidae for which the structure has been described. In Neoeutegaeidae fam. nov. pd I is sub-rectangular, pd II is massive and either trapezoid or lobe-like and the discidium is lobe-like or sub-circular. In Compactozetidae , pd I has a prominent anterior spine, pd II is very large and lobe-like or rectangular and the discidium is lobe-like or sub-triangular. In Pterozetidae pd I is sub-rectangular, pd II is rectangular and the discidium is rectangular or trapezoid. In Porrhotegaeidae fam. nov. pd I and II are sub-rectangular, pd I lacks a spine and the discidium is triangular and pointed.

Figures

FIGURE 27. Scanning electron micrographs of Neoeutegaeus sp. from O’Reilly’s Rainforest Retreat, Lamington National Park, Queensland (from Hunt et al., 1998b).

FIGURE 44. Distribution of type localities of species of Eutegaeoidea superimposed on a map of Gondwana prior to its break-up during the middle Jurassic (re-drawn from Veevers, 2000). Note that only genera present on more than one former Gondwanan land mass are included.