Protoribates tibetensis, Chen & Chen, 2020

Chen, Shujing Xu Yannan & Chen, Jun, 2020, New species and records of oribatid mites of the genus Protoribates (Acari Oribatida, Haplozetidae) from China, Zootaxa 4772 (3), pp. 469-511 : 474-477

Protoribates tibetensis sp. nov.

( Figs. 1–6 )

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Diagnosis. Body size 520–700 × 310–460. Rostral, lamellar and interlamellar setae long, setiform, barbed, le insert- ed on lamellar ends. Bothridial setae with long stalk and short, unilaterally slightly dilated, apically pointed, barbed head. Notogastral setae setiform, setae c short, thin, smooth, others long, thick, barbed, blunt distally. Distance between porose areas A1–A1 subequal to A2–A2. Epimeral setal formula: 3-1-3-3; setae 3с longest. Circumpedal carinae of medium size, directed to region of acetabula III. Custodium present. Adanal setae ad 1 and ad 2 of medium size, thick, barbed. Legs monodactylous. Five pairs of genital setae. Femora II ventroanteriorly rounded.

Description. Measurements. Body length: 570 (holotype, male), 520–700 (15 paratypes: six females and nine males); notogaster width: 370 (holotype), 310–460 (15 paratypes). Females usually larger than males: 600–700 × 380–460 versus 520–625 ×310–385.

Integument. Body color brown. Body surface punctate. Lateral parts of prodorsum between sublamellae and acetabula I, II microgranulate.

Prodorsum ( Figs 1A, B , 3A ). Rostrum broadly rounded. Lamellae located dorsolaterally, half as long as prodorsum (measured in lateral view). Sublamellae about half as long as lamellae. Sublamellar porose areas oval (22–30 × 10–15), located very near to sublamellae. Rostral (75–92), lamellar (88–120) and interlamellar (108–158) setae setiform, barbed, le inserted on lamellar ends. Bothridial setae (105–145) with long stalk and short, unilaterally slightly dilated, apically pointed, barbed head. Exobothridial setae (30–45) thin, barbed. Dorsophragmata comparatively short, longitudinally elongated, directed posteromedially. Tutorium ridge-like.

Notogaster ( Figs 1A, C , 3 ). Anterior notogastral margin convex medially. Pteromorphs with distinct hinges. Ten pairs of notogastral setae setiform, setae c (12–15) short, thin, smooth, others long (34–70), thick, barbed, blunt distally. Four pairs of rounded porose areas, Aa (10–15) larger than A1, A2 and A3 (4–8). Distance between A1–A1 subequal to A2–A2. Seta lp inserted anteromedially to A1, seta h 3 inserted far anteriorly to A2. All lyrifissures and opisthonotal gland openings clearly visible, ip located posterolaterally to A3.

Gnathosoma ( Fig. 6 ). Subcapitulum longer than wide (125–165 × 85–105). Subcapitular setae setiform, h longest (31–44), barbed, a (23–32) roughed, m shortest (15–22), thinnest. Palps (length 80–95) with setation 0-2-1- 3-9(+ω). Postpalpal setae (6–8) spiniform. Chelicerae (length 120–165) setae barbed, cha (50–55) longer than chb (28–35). Trägårdh’s organ long, tapered.

Epimeral and lateral podosomal regions ( Figs 2 , 3A ). Epimeral setal formula: 3-1-3-3. Setae setiform, thin, 3c, 1b and 3b barbed, 3с (35–43) longer than 1b and 3b (28–38), others short (12–25), roughed. Pedotecta I and II lamina-like. Discidium triangular. Custodium present. Circumpedal carinae of medium size, directed to region of acetabula III.

Anogenital region ( Figs 2 , 3 ). Five pairs of genital (g 1, 17–25; g 2 –g 5, 10–20), one pair of aggenital (14–20) setae, slightly barbed, two pairs of anal (25–44) and three pairs of adanal setae (a d 1, 67–88; ad 2, 56–80; a d 3, 26–35) setiform, barbed, ad 1 and ad 2 obviously longer than ad 3. Adanal setae ad 1 posterior, ad 2 lateral, ad 3 anterior to anal aperture. Adanal lyrifissures located close and parallel to anal plates.

Legs ( Figs 4 , 5 ). Monodactylous, claws thick, barbed dorsally. Tibiae I and II with ventrobasal tooth. Femora II ventroanteriorly rounded. Dorsoparaxial porose areas on femora I–IV and on trochanters III, IV well visible. Formulas of leg setation and solenidia: I (1-5-3-4-20) [1-2-2], II (1-5-3-4-15) [1-1-2], III (2-3-1-3-15) [1-1-0], IV (1-2-2-3-12) [0-1-0]; homology of setae and solenidia indicated in Table 1.

Roman letters refer to normal setae, Greek letters to solenidia (except ɛ = famulus). Single prime (’) marks setae on the anterior and double prime (”) setae on the posterior side of a given leg segment.

*— l” on tarsus IV absent in Protoribates sichuanensis sp. nov. and Protoribates oblongus (Ewing, 1909) .

Material examined. Holotype (male, in alcohol, LR-17-115): China, Tibet, Medog County, Beibeng Town, Jiangxin Village , 29°13′23.80″N, 95°07′45.18″E, 743 m a.s.l., litter under arbor, 12.VIII.2017; nine paratypes (six males, three in alcohol and three on permanent slides; three females, one in alcohol and two on permanent slides, LR-17-115): same data as the holotype; four paratypes (two males, one in alcohol and one on permanent slide; two females, one in alcohol and one on permanent slide, LR-17-088): China, Tibet, Medog County , 108 Km milestone locality on Zamo Road, 29°29′28.07″N, 95°26′42.88″E, 904 m a.s.l., in mosses, 7.VIII.2017; one paratype (female on permanent on slide, LR-17-129): China, Tibet, Medog County , near Ximohe Bridge, 29°21′06.27″N, 95°20′27.17″E, 758 m a.s.l., litter under arbor, 15.VIII.2017; one paratype (male in alcohol, LR-17-130): same place as LR-17-129, 29°21′23.32″N, 95°20′26.86″E, 766 m a.s.l., litter under arbor, 15.VIII.2017. All specimens were collected by Rong Li.

Etymology. The species is named after the region, Tibet in China, from where the type specimens were collected.

Remarks. By having the combination of larger body size, long, thick and barbed notogastral setae, long, thick, and barbed ad 1 and ad 2, custodium and monodactylous legs, Protoribates tibetensis sp. nov. differs from all representatives of the genus Protoribates . The presence of developed notogastral setae is unusual for Protoribates . There are only two species of Protoribates whose notogastral setae are moderately long, the others are minute or short. They are P. mollicoma ( Hammer, 1973) from Pacific Islands and India, and P. lemensis Ermilov & Tolstikov, 2015 from Brazil, but the notogastral setae of both of above are smooth, not barbed, and custodium abstent.

Although the presence of long notogastral setae is unusual for the genus, the other characters such as porose areas on notogaster, the form of tutorium, leg chaetotaxy, and the number of genital setae are generally typical for Protoribates .

Figures

FIGURE 1. Protoribates tibetensis sp. nov., adult. A. dorsal view; B. bothridial setae; C. notogastral setae except setae c. Scale bars: A=100 μm, B=50 μm, C=25 μm.

FIGURE 2. Protoribates tibetensis sp. nov., adult. ventral view. Scale bar 100 μm.

FIGURE 3 Protoribates tibetensis sp. nov., adult. A. anterior part of body, lateral view; B. posterior part of body, lateral view. Scale bar 100 μm.

FIGURE 4. Protoribates tibetensis sp. nov., adult.A. leg I, right, antiaxial view; B. genu, femur and part of trochanter of leg II, right, antiaxial view. Scale bar 50 μm.

FIGURE 5. Protoribates tibetensis sp. nov., adult.A. tarsus of leg II, right, antiaxial view; B. genu, femur and trochanter of leg III, right, antiaxial view; C. leg IV, right, antiaxial view. Scale bar 50 μm.

FIGURE 6. Protoribates tibetensis sp. nov., adult. A. subcapitulum, ventral view; B. palp, right, antiaxial view; C. chelicera, right, antiaxial view. Scale bars 50 μm.