Humerobates ulleungdoensis, Bayartogtokh & Bae, 2024

Bayartogtokh, Badamdorj & Bae, Yang-Seop, 2024, New findings of poronotic oribatid mites (Acari: Oribatida) from Korea, Zootaxa 5405 (2), pp. 151-184 : 158-161

Humerobates ulleungdoensis sp. nov.

( Figures 5 & 6 )

Diagnosis. Body length 502–567 μm, width 378–421. Rostrum bidentate. Prolamellar ridge absent. All prodorsal setae long, distinctly barbed. Bothridial seta with short peduncle and large, clavate head, with spiculate surface. Lamella narrow, with distinct cusp like large lateral tooth; translamella absent. Tutorium large, narrowed basally, with longitudinal striations, distally with prominent cusp, not dentate. Notogastral setae represented by their alveoli; pteromorph large, curved ventrad, with line of desclerotization; porose areas circular or subcircular, with indistinct rims. Anal and adanal setae represented by their alveoli; legs heterotridactylous.

Measurements. Body length: 502–567 (536) μm, width of notogaster 378–421 (396) μm, length of notogaster 454–502 (471) μm.

Integument. Body colour yellowish brown; microtuberculate over whole body and leg segments; excrescences of cerotegument granular; restricted to region between pteromorph, pedotectum I, tutorium and lateral side of body.

Prodorsum ( Figs. 5A, C , 6A, C ). Rostrum bidentate; prolamellar ridge absent. Rostral seta (ro) barbed, ~109 μm long. Lamella narrow, with distinct cusp like large lateral tooth; translamella absent. Lamellar seta (le) ~147 μm long, barbed. Interlamellar seta (in) ~155 μm long, barbed. Exobothridial seta (ex) ~38 μm long, barbed. Bothridial seta (bs) ~42 μm long, with short peduncle and large, clavate head, with spiculate surface. Bothridium oval, with ventrolateral and ventromedial scales. Tutorium large, ~197 μm long, narrowed basally, with longitudinal striations, distally with prominent cusp, not dentate. Humerosejugal porose area AJ present, hardly discernible; porose areas Am, Ah not evident. Genal tooth narrow, pointed distally. Pedotectum I large, with convex dorsal margin, partly covering base of seta ex.

Notogaster ( Figs. 5A , 6A ). Longer than wide, ratio about 1.2:1.0; anterior margin broadly rounded. Pteromorph large, curved ventrad, with line of desclerotization. Ten pairs of notogastral setae represented by their alveoli. Four pairs of porose areas circular or subcircular, with indistinct rims. Opisthonotal gland opening (gla) and lyrifissures ia, im, ih, ips and ip well developed, in normal positions. Posterior notogastral tectum present.

Gnathosoma ( Figs. 5B , 6B ). Typical for family (e.g., Behan-Pelletier & Mahunka 1993; Ermilov et al. 2011). Subcapitulum wider than long; subcapitular setae a, m and h setiform, smooth, 21–24 μm long. Palp and chelicera typical for family; palpal setation: 0–2–1–3–9(+ω), solenidion bacilliform; cheliceral setae setiform, barbed; cha longer than chb.

Epimeral region ( Figs. 5B , 6B ). Epimeres without muscle sigillae; apodemes apo.2, apo.sj and apo.3 well developed. Epimeral setae smooth, 18–35 μm long, setal formula: 3–1–3–3; seta lb, 3b, 3c and 4b distinctly longer than other setae. Discidium large, projected distally, but not sharp; custodium short, extending anteriad to level of posterior margin of leg acetabulum II. Circumpedal carina short, not reaching to base of pedotectum I, but complete laterally, reaching margin of ventral plate.

Anogenital region ( Figs. 5B , 6B ). Genital and aggenital setae well developed; six pairs of genital setae, g 1 – g 4 inserted close to anterior margin of genital plate, g 5 and g 6 close to posterior margin. Anal and adanal setae represented by their alveoli; ad 1 and ad 2 inserted posterior, ad 3 lateral to anal aperture. Lyrifissure iad located close and parallel to anterolateral margin of anal aperture. Postanal porose area small, oval.

Legs. Medial claw thicker than lateral claws, tarsi without pulvillus. Structure and setation of legs same as those of previous species.

Material examined. Holotype (female) and six paratypes (five females and two males): San 171, Taeha-ri , Seo-myeon , Ulleung-gun , North Gyeongsang Province, Korea, 37°29’35.13”N, 130°49’40.71”E, soil and litter of mixed forest composed by Siebold humlock ( Tsuga sieboldii Carrière ), Japanese white pine ( Pinus parviflora Siebold & Zuccarini ) and Engler’s beech ( Fagus engleriana Seemen ex Diels ), 26 May 2022, Coll. T. G. Lee.

Etymology. The specific name “ ulleungdoensis ” refers to the name of the island Ulleungdo, which mainly compose the Ulleung county, located in the east of Korean peninsula, from which we recovered this species.

Remarks. The present new species clearly differs from all other known species of Humerobates in the relatively small circular or subcircular porose areas with indistinct rims; development of large cusp-like lateral tooth of lamellar cusp; ventrally bent pteromorph with no radiating vein-like ridges; and absence of anal and adanal setae, which represented by their alveoli.

In general appearance, this species is similar to Humerobates aokii sp. nov. However, it differs from the latter species in the distinctly bidentate rostrum; relatively long interlamellar seta, which is reaching tip of rostrum; relatively smaller bothridial seta; proximally conspicuously narrowed and distally not striated tutorium, and much larger body size.

Figures

FIGURE 5. Line drawing images of Humerobates ulleundoensis sp. nov. A—Dorsal view; B—Ventral view of body; C—Lateral view of proterosoma.

FIGURE 6. Compound microscopic images of Humerobates ulleundoensis sp. nov. A—Dorsal view; B—Ventral view of body; C—Lateral view of proterosoma.