Tritegeus mitratus ( Aoki, 1967 ), 2024

Ermilov, Sergey G., 2024, Taxonomic contribution to knowledge of the oribatid mite genus Tritegeus (Acari, Oribatida, Cepheusidae), Zootaxa 5556 (1), pp. 37-50 : 46-48

Tritegeus mitratus ( Aoki, 1967)

( Figs 5 , 6 )

Material. Three specimens (one male and two females): Japan, Shikoku , Ishizuchi Mountain National Park , Tsuchigoya, Mt. Kamegamori, 1650 m a.s.l., abies and moss litter, with fungi and moss 15.VIII.1980 (S. Peck) .

All specimens (preserved in 70% solution of ethanol with a drop of glycerol) are deposited in the collection of the University of Tyumen, Museum of Zoology , Tyumen, Russia .

Supplementary description of adult. Measurements. Body length: 780–825; notogastral width: 550–600.

Integument ( Figs 5A–C ). Body color dark brown. Body and legs partially covered by thick gel-like layer of cerotegument, including dense microtubercles, larger near the U-shaped thickening on notogaster; lamella, epimere I, pedotecta I, II, discidium, lateral part of prodorsum partially foveate; lateral side of body between humeral process and acetabula II – IV with dense large tubercles; anogenital region with heavy ridges; marginal region of notogaster with some longitudinal ridges; additionally, humeral process, podosomal region and dorsal part of pedotectum I partially rugose.

Prodorsum ( Figs 5A–C ). Rostrum pointed, not observable in dorsal aspect. Rostral region with short transverse ridge. Lamellar cusps fused mediodistally on significant continuation (hence, translamella absent); outer tooth of lamellar cusp well developed. Tutorium with numerous teeth and small scales dorsally. Rostral seta (86–94) setiform, with short, flexible tip, barbed; lamellar seta (131–154) with thickened mediobasal part and flagellate distal part, with sparse barbs; interlamellar seta (176–195) thickened, acuminate, roughened; bothridial seta (90–94) with longer stalk and short expanded head bearing numerous strong spines; exobothridial seta (56–60) setiform, roughened.

Notogaster ( Figs 5A–D ). Centrodorsal region bordered by U-shaped thickening bearing dorsal notogastral setae. Setae h 1 (49–56) and p 1 (56–64) thickened, acuminate, heavily barbed; p 2, p 3 (34–41) slightly stiff, roughened; other setae (86–94) thickened, acuminate, roughened. Opisthonotal gland opening and all lyrifissures observable.

Gnathosoma ( Figs 6A–C ). Subcapitulum size: 146–157 × 105–112; subcapitular setae (a: 30–34; m: 19–22; h: 30–37) setiform, roughened; m thinnest; both adoral setae (17–19) setiform, smooth. Palp length: 82–86; postpalpal seta (11) spiniform, roughened. Chelicera length: 146–161; setae (cha: 34–37; chb: 26–30) setiform, barbed.

Epimeral and podosomal regions ( Figs 5B, C ). All epimeral setae (3c, 4c: 56–64; 1b: 37–45; 1c, 3b, 4a, 4b: 30; 1a, 2a, 3a: 11) setiform, roughened. Discidium large, elongate triangular, rounded distally.

Anogenital region ( Figs 5B–D ). Genital (g 1, g 2: 26–30; g 3: 22–26; others: 15–19), aggenital (22–26), anal (22– 26), and adanal (ad 1: 30–34; others: 26–30) setae setiform, roughened. Adanal lyrifissure distinct, oblique.

Legs ( Figs 6D–G ). All tarsi with three claws; median claw thicker than lateral claws; all claws slightly barbed on dorsal side. Trochanters III and IV with long tooth dorsoanteriorly. Formulas of leg setation and solenidia: I (1- 5-3-4-20) [1-2-2], II (1-4-3-4-16) [1-1-2], III (2-3-2-3-15) [1-1-0], IV (1-2-3-3-12) [0-1-0]; homology of setae and solenidia indicated in Table 1; comparison of morphology of some setae between T. mitratus , T. tridactylus and T. luissantossubiasi presented in Table 2.

Remarks. Based on the original description ( Aoki 1967) and the data presented here, the following diagnostic traits for T. mitratus are proposed:

Adult. Body size: 780–840. Notogaster foveolate. Rostrum pointed. Lamellar cusps fused mediodistally (rostrum not observable in dorsal aspect). Rostral seta setiform, with short, flexible tip, barbed; lamellar seta with thickened mediobasal part and flagellate distal part, with sparse barbs; interlamellar seta thickened, acuminate, roughened; in˃le˃ro; bothridial seta with shortly expanded head bearing numerous strong spines. Centrodorsal region of notogaster bordered by U-shaped thickening. Notogastral setae h 1 and p 1 comparatively short (p 1 slightly longer than h 1) thickened, acuminate, heavily barbed; p 2, p 3 shortest, slightly stiff, roughened; other setae medium-sized, thickened, acuminate, roughened. All leg tarsi heterotridactylous; trochanters III and IV with long tooth dorsoanteriorly; seta pv’ on Ta I, II with ventral sparse spines; l” on Ti I, II setiform; v’ on Ti I, II setiform, with ventral sparse spines; l” on Ge I, II setiform.

Figures

FIGURE 5. Tritegeus mitratus (Aoki, 1967), adult:A—dorsal view (legs not illustrated); B—ventral view (legs not illustrated); C—lateral view (legs not illustrated); D—posterior view (part of left half not illustrated). Scale bar 200 μm.

FIGURE 6. Tritegeus mitratus (Aoki, 1967), adult:A—subcapitulum, ventral view; B—palp, right, antiaxial view; C—chelicera, right, antiaxial view; D—leg I, right, antiaxial view; E—leg II, right, antiaxial view; F—leg III, left, antiaxial view; G—leg IV, left, antiaxial view. Scale bars 50 μm (A, C–G), 20 μm (B).