Tritegeus, Berlese, 1913

Ermilov, Sergey G., 2024, Taxonomic contribution to knowledge of the oribatid mite genus Tritegeus (Acari, Oribatida, Cepheusidae), Zootaxa 5556 (1), pp. 37-50 : 38-39

Synonymy of Tritegeus and Sphodrocepheus

Woolley and Higgins (1963) proposed the genus Sphodrocepheus without comparison with related genera. Balogh (1972) considered that this genus differs from Tritegeus by having a pair of the longitudinal dorsolateral thickenings bordering the centrodorsal part of the notogaster, which bear the dorsolateral setae (whereas Tritegeus lacks these thickenings). Sitnikova (1975 b) observed that Sphodrocepheus is distinguished from Tritegeus by the presence of the very large lamellae that cover the rostrum and are connected by a broad translamella (in contrast, Tritegeus has lamellae that do not cover the rostrum and the translamella is not broad). Balogh and Balogh (1992) considered that Sphodrocepheus differs from Tritegeus by the presence of dorsolateral thickenings and rough sculpture on the notogaster, which are absent in Tritegeus .

However, a comparison of the descriptions and supplementary descriptions of the type species of Sphodrocepheus and Tritegeus — S. tridactylus (see data of this paper) and T. bisulcatus (see S. Bernini & Bernini 1990; Pérez-Íñigo 1997; Weigmann 2006), respectively—reveals that the previously noted differences between these genera are inaccurate. Both S. tridactylus and T. bisulcatus share the following traits: 1) longitudinal dorsolateral thickenings bordering the centrodorsal part of the notogaster and bearing dorsolateral setae; 2) lamellae that do not cover the rostrum and are narrowly separated medially (translamella absent); 3) absence of rough sculpture on the notogaster. Woolley and Higgins (1963; Fig. 1 on p. 146) figured a wide translamella in S. tridactylus , but their figure is inaccurate. In reality (see supplementary description below) the lamellae are separated, with their medial parts slightly protruding anteromedially, creating the illusion of a thin translamella.

Hence, there is no difference between the genera Sphodrocepheus and Tritegeus . Therefore, I support the assumption of Bayartogtokh and Ermilov (2021) regarding the synonymy of Sphodrocepheus with Tritegeus , and propose final taxonomic proposals accordingly: Tritegeus Berlese, 1913 (= Sphodrocepheus Woolley & Higgins, 1963 syn. nov.); Tritegeus anthelionus ( Woolley & Higgins, 1968) comb. nov.; Tritegeus dentatus ( Fujikawa, 1972) comb. nov.; Tritegeus mitratus ( Aoki, 1967) comb. nov.; Tritegeus tridactylus ( Woolley & Higgins, 1963) comb. nov.; Tritegeus tuberculatus ( Mahunka, 1988) comb. nov.

Generic diagnosis

Adult. With character states of Cepheusidae (e.g. Sitnikova 1975 a; S. Bernini & Bernini 1990; Weigmann 2006; Norton & Behan-Pelletier 2009). Body size: Large (length more than 600). Integument: Surface microsculpturing microtuberculate; additionally, prodorsum partially foveate, notogaster frequently areolate, podosomal region partially tuberculate, anogenital region can be partially foveate or rugose. Prodorsum: Rostrum rounded or pointed. Lamella located dorsolaterally on prodorsum, comparatively long and broad; lamellae separated or connected by translamella mediodistally, sometimes entirely fused; cusp of lamella with outer tooth. Prolamella absent or vestigial. Sublamella and sublamellar porose area absent. Tutorium long, ridge-like, heavily dentate dorsally. Rostral, lamellar and interlamellar setae comparatively long, setiform/subflagellate/rod-like/thickened: le inserted on lamellar cusp; in inserted in interbothridial region; bothridial seta with or without head; exobothridial seta present. Bothridium cupshaped. Interbothridial region without tubercles. Dorsosejugal porose area and dorsophragma absent; pleurophragma present. Genal tooth large, elongate triangular. Notogaster: Anterior notogastral margin convex or straight medially. Humeral region with small, rounded projection. Pteromorph and octotaxic system absent. Ten pairs of notogastral setae (centrodorsal part of notogaster without setae) mainly rod-like/thickened, sometimes slightly dilated distally, inserted on notogastral surface or on tubercles; setae h 1 and p 1 inserted close to each other and usually shorter than dorsal setae. Gnathosoma . Subcapitulum diarthric, with setiform subcapitular setae. Palp with setation: 0–2–1–3– 9(+ω); solenidion bacilliform, coupled with eupathidium mediodistally. Axillary saccule absent. Chelicera chelatedentate. Epimeral and lateral podosomal regions: Epimeral setal formula: 3–1–3–3; all epimeral setae setiform. Enantiophyses and tubercles absent. Pedotectum I represented by large scale divided into two parts (dorsal part triangular; ventral part simple); pedotectum II represented by small scale. Humeral porose area absent. Circumpedal carina and discidium present. Anogenital region: Setal formula: 6–1–2–3; all setae comparatively short, mainly setiform. Marginal porose area absent. Adanal lyrifissure oblique or transverse, lateral and slightly distanced from anterior margin of anal plate. Legs: All legs heterotridactylous, rarely monodactylous. Dorsoparaxial porose area on femora I–IV and on trochanters III, IV present; distoventral porose area on tibiae I–IV and proximoventral porose area in tarsi I–IV present or not observable.

Figures

FIGURE 1. Tritegeus tridactylus (Woolley & Higgins, 1963), adult: A—dorsal view (legs not illustrated); B—ventral view (legs not illustrated); C—lateral view (gnathosoma and legs not illustrated); D—posterior view (part of left half not illustrated). Scale bar 200 μm.