Protoribates oblongus (Ewing, 1909)

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 : 494-500

Protoribates oblongus (Ewing, 1909)

( Figs 17–22 )

Xylobates oblonga Ewing, 1909a: 73–74 , fig. 37.

Oribata longa Ewing, 1909b: 362–363 , fig. 6; Norton & Kethley, 1989: 490, 493 (synonymy).

Xylobates longus (Ewing, 1909) : Marshall et al. 1987: 267.

Xylobates longisetae Jacot, 1937: 244–245 , figs 17–21; Marshall et al. 1987: 267; Norton & Kethley, 1989: 490, 493 (synonymy).

Hemileius oblongus (Ewing, 1909) : Woolley, 1961: 4–6, figs 5–6.

Xylobates oblongus (Ewing, 1909) : Norton & Kethley, 1989: 490, 493.

Protoribates oblongus (Ewing, 1909) : Weigmann et al., 1993: 39; Subías, 2004: 206.

Supplementary description. Body length 385–560, width 185–325. Females larger than males: 500–560 × 300– 325 versus 385–450 ×185–250. Body color brown. Body surface punctate. Lateral parts of prodorsum between sublamellae and acetabula I, II microgranulate.

Prodorsum ( Figs 17 , 20A ). Rostrum truncate at tip. Lamellae located dorsolaterally, half as long as prodorsum (measured in lateral view). Sublamellae about half as long as lamellae. Sublamellar porose areas oval (13–20 × 8–12), located very near to sublamellae. Rostral (40–50), lamellar (70–95) and interlamellar (80–116) setae setiform, barbed, le inserted on inside lamellar ends. Bothridial setae (88–115) with long stalk and short, unilaterally dilated, apically pointed, barbed head, the number of barbs on head of bothridial setae different (3–12) (fig 17B). Exobothridial setae (8–10) thin, smooth. Dorsophragmata comparatively short, longitudinally elongated, directed posteromedially. Tutorium ridge-like.

Notogaster ( Figs 17A , 18 , 20 ). Anterior notogastral margin convex medially. Pteromorphs with distinct hinges. Ten pairs of notogastral setae minute (4–6), thin, smooth. Four pairs of rounded porose areas, Aa (10–16) larger than A1, A2 and A3 (6–13), A1 occasionally divided into two closely situated pores on one side of one specimen. Distance between A1–A1 shorter than A2–A2 (0.42–0.65). Setae h 1 and h 2 almost in transverse line, sometimes h 1 anterior ( Figs 17A , 18B ), sometimes h 2 anterior ( Fig. 18A ). Distance between h 3 and A2 varied, sometimes h 3 away from A2 ( Figs 17A , 18A ), sometimes h 3 close to A2 ( Fig. 18B ). All lyrifissures and opisthonotal gland openings clearly visible, ip located posterolaterally to A3.

Gnathosoma ( Fig. 19B ). Subcapitulum longer than wide (110–140 × 70–95). Subcapitular setae setiform, h longest (24–40), barbed, a (16–22) roughed, m shortest (10–21), thinnest. Adoral setae (14–17) setiform, heavily barbed. Palps (length 70–88) with setation 0-2-1-3-9(+ω). Postpalpal setae (6–8) spiniform. Chelicerae (length 120–145) with two barbed setae, cha (41–49) longer than chb (20–25). Trägårdh’s organ long, tapered.

Epimeral and lateral podosomal regions ( Figs 19 , 20A ). Epimeral setal formula: 3-1-3-2. Setae setiform, thin, smooth, except 3с (25–38), barbed, usually longer than 3b (20–38) and 1b (20–30) and others (10–16), 3b longer than 3c occasionally. Humeral porose areas Ah oval. Pedotecta I and II lamina-like. Discidium triangular. Custodium absent. Circumpedal carinae long, directed to region of acetabula II, but not reaching it.

Anogenital region ( Figs 19 , 20 ). Five pairs of genital (g 1, 10–17; g 2 –g 5, 8–13), one pair of aggenital (ag, 8–16), two pairs of anal (18–25) and three pairs of adanal (ad 1, 35–50; ad 2, 20-40; ad 3, 10–18) setae setiform, thin, smooth. Adanal setae ad 1 and ad 2 of medium size, longer than ad 3 and anal setae an 1 and an 2. Adanal setae ad 1 posterior, ad 2 posterolateral, ad 3 anterior to anal aperture. Adanal lyrifissures located close and parallel to anal plates.

Legs ( Figs 21 , 22 ). 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 (1-5-3-4-19) [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.

Material examined. Three specimens (two males, one in alcohol and one on permanent slide, one female in alcohol, LR-17-032): China, Tibet, Bomi County, Yigong Village , 41 Km milestone locality on Provincial Road 305, 30°16′02.38″N, 94°46′46.34″E, 2216 m a.s.l., litter under Pinus sp., 31.VII.2017 ; three specimens (two females, one in alcohol and one on permanent slide, one male on permanent slide, LR-17-051): China, Tibet, Bomi County, Yigong Village , 32 Km milestone locality on Provincial Road 305, 30°14′23.62″N, 94°51′30.00″E, 2236 m a.s.l., litter, 2.VIII.2017 ; two specimens (males in alcohol, LR-17-058): China, Tibet, Nyingchi County, Pailong Town, Polonggou , 30°01′37.58″N, 95°00′51.20″E, 2018 m a.s.l., litter under arbor, 3.VIII.2017 ; three specimens (females on permanent slides, LR-17-111): China, Tibet, Medog County, Beibeng Town, Jiangxin Village , 29°13′08.48″N, 95°07′53.90″E, 893 m a.s.l., litter under Alpinia sp., 12.VIII.2017 ; eight specimens (five males, four in alcohol and one on permanent slide; three females in alcohol, LR-17-115): same place as LR-17-111, 29°13′23.80″N, 95°07′45.18″E, 743 m a.s.l., litter under arbor, 12.VIII.2017; two specimens (females, one in alcohol and one on permanent 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 ; three specimens (two females and one 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; one speci- men (male in alcohol, LR-17-132): same place as LR-17-129, 29°21′28.14″N, 95°20′28.62″E, 769 m a.s.l., litter under Musa sp., 15.VIII.2017; three specimens (two males and one female in alcohol, LR-17-133): same place as LR-17-129, 29°21′33.41″N, 95°20′33.25″E, 782 m a.s.l., litter under arbor, 15.VIII.2017; six specimens (four females, three in alcohol and one on permanent slide; two males, one in alcohol and one on permanent slide, LR- 17-145): China, Tibet, Bomi County, Kada Village , 29°55′01.16″N, 95°37′37.36″E, 2707 m a.s.l., litter under shrub, 17.VIII.2017 ; four specimens (three females, two in alcohol, one on permanent slide; one male in alcohol, LR-17- 146): same place as LR-17-145, mosses, 17.VIII.2017. All specimens were collected by Rong Li.

Distribution. China (Tibet), Nearctic and Lesser Antilles.

Remarks. Woolley (1961) redescribed the species as Hemileius oblongus (Ewing, 1909) probably based on Ewing’s description and illustration since he did not examine the actual specimens in most instances. Norton & Kethley (1989) examined the type specimens and considered that Xylobates longus (Ewing, 1909) and X. longisetae Jacot, 1937 are junior synonyms of X. oblongus Ewing, 1909 . In that paper, they stated that the density of the barbs of bothridial setae varied and the body size ranged from 465 to 550 μm. They examined approximately 20 American specimens of oblongus and all of them were female.

According to the descriptions and illustrations of oblongus , longus and longisetae ( Woolley, 1961, Ewing, 1909a, b, Jacot, 1937), the specimens we examined are similar to P. oblongus by long, smooth adanal setae, long and barbed rostral, lamellar and interlamellar setae, same position of porose areas and setae on notogaster, ventroanteriorly rounded femora II and bothridial setae with long, barbed unilaterally stalk and short, apically pointed, unilaterally dilated, barbed head, and the number of barbs on bothridial setal head varied from three to 12 (even in one specimen, with differences on both sides: three and six), coincident with the description in Norton & Kethley (1989). The body size of the specimens we examined ranges from 385–560, and females larger than males: 500–560 versus 385–450, also within the size range given by Norton & Kethley (1989). Based on the above, we consider our specimens to be conspecific with Protoribates oblongus , found in Asia for the first time.

Protoribates oblongus is morphologically similar to P. hakonensis Aoki, 1994 from Japan, Bulgaria and Vietnam; P. iracemae Pérez-Íñigo & Baggio, 1994 from Brazil and Ecuador; P. osunensis Badejo, Woas & Beck, 2003 from Nigeria; and P. rioensis Badejo, Woas & Beck, 2003 from Brazil in having long prodorsal setae, long adanal setae ad 1 and ad 2, and monodactylous legs. However, it differs from P. hakonensis by setae h 3 closer to A2 than to opisthonotal gland openings gla (vs. h 3 closer to opisthonotal gland openings gla than to A2); setae h 2 posterior to the level of A2 (vs. setae h 2 close to A2); adanal setae ad 1 always longer than ad 2 (vs. adanal setae ad 1 almost equal to ad 2); setae ro and le barbed (vs. setae ro and le smooth). It differs from P. iracemae by setae lm anterior to the level of la (vs. setae lm posterior to the level of la); setae ro, le and in barbed (vs. setae ro, le and in smooth); bothridial setae with barbed stalk and head (vs. bothridial setae with barbed head only); ten pairs of notogastral setae present (vs. ten pairs of notogastral setae reduced to alveolus). It differs from P. osunensis by adanal setae ad 1 and ad 2 smooth (vs. adanal setae ad 1 and ad 2 barbed); anterior notogastral margin convex medially (vs. anterior notogastral margin straight). It differs from P. rioensis by adanal setae ad 1 and ad 2 smooth (vs. adanal setae ad 1 and ad 2 barbed); rostrum truncate (vs. rostrum emarginate).

The species is also morphologically similar to P. diani ( Mahunka, 1986) from Kenya; P. ecuadoriensis Ermilov, Bayartogtokh, Sandmann, Marian & Maraun, 2013 from Ecuador; P. paraecuadoriensis Ermilov & Friedrich, 2016 from Peru; P. taira Fujikawa, 2006 from Japan; P. triangularis ( Hammer, 1971) from Pacific Islands and India; and P. yezoensis ( Fujikawa, 1983) from Japan in the position of porose areas and setae on notogaster and monodactylous legs. However, it differs from all of the latter in having adanal setae ad 1 and ad 2 obviously longer than anal setae (vs. adanal seate ad 1 and ad 2 similar to anal setae in length).

Figures

FIGURE 17. Protoribates oblongus (Ewing, 1909), adult. A. dorsal view; B. bothridial setae. Scale bars: A=100 μm, B=50 μm.

FIGURE 18. Protoribates oblongus (Ewing, 1909), adult, showing variations among individuals.A. dorsal view (setae h2 anterior to h1, setae h3 away from A2); B. dorsal view (h3 close to A2, setae h1 anterior to h2). Scale bars 100 μm

FIGURE 19. Protoribates oblongus (Ewing, 1909), adult. A. ventral view; B. subcapitulum, ventral view. Scale bars: A=100 μm, B=30 μm.

FIGURE 20. Protoribates oblongus (Ewing, 1909), adult.A. anterior part of body, lateral view; B. posterior part of body, lateral view. Scale bar 100 μm.

FIGURE 21. Protoribates oblongus (Ewing, 1909), adult.A. leg I, right, antiaxial view; B. genu, femur of leg II, right, antiaxial view. Scale bar 30 μm.

FIGURE 22. Protoribates oblongus (Ewing, 1909), adult.A. tarsus of leg II, right, antiaxial view; B. genu, femur and trochanter of leg III, left, antiaxial view; C. leg IV, left, antiaxial view. Scale bar 30 μm.