Podocinum tibetensis, Yan, Yi, Jin, Dao-Chao, Wu, Dian, Guo, Jian-Jun & Guo, Xian-Guo, 2012

Yan, Yi, Jin, Dao-Chao, Wu, Dian, Guo, Jian-Jun & Guo, Xian-Guo, 2012, A revised checklist and key to the genus Podocinum Berlese (Acari: Podocinidae) with description of a new species from Tibet, Southwest China, Zootaxa 3194, pp. 35-48 : 36-42

Description of Podocinum tibetensis sp. nov.

( Figures 1–19 )

Types. Holotype female, Bome County (29°53' N, 95°40' E), Nyingchi, Tibet Autonomous Region, China, 2726 m a.s.l., 25 August 2010, Yun-chun Li coll., in litter under pine tree. Paratypes: 5 females, same data as holotype.

Diagnosis (female). Dorsal shield entire, extending posteriorly and laterally onto ventral surface, completely covered with small protuberances connected to one another by bridges; protuberances and bridges arranged in a distinct polygonal network. Dorsal shield with eight pairs of prominent pores and 19 pairs of setae (S4, S5 located ventrally). The distance between the bases of j1 is approximately equal to double the length of j1. Setae j2 and six pairs of opisthosomal setae (J3, Z3, J4, Z4, J5 and S5) are thick, long and pilose. The ventri-anal shield is pentagonal, broader than long. The fixed digit of the chelicera has three large and four small teeth. The central prong of the epistome has three branches. The length of the longest sub-distal seta on tarsus I is approximately double the distance between the setal base and the distal end of tarsus I.

Idiosoma ( Fig. 19 ). Shape oval, colour golden-brown. Length of idiosoma 440–470, width at the level of coxae IV 340–357.

Dorsal idiosoma ( Fig. 1 ). Dorsal shield entire, extending posteriorly and laterally onto ventral surface. Margins of dorsal shield finely dentate, length 480–504, width 365–403 between coxae III and IV. Entire surface covered with small protuberances connected by bridges, protuberances and bridges arranged in a distinct polygonal network of pentagons, hexagons or quadrilaterals (rarely). Tuberculate polygonal areas enclose a variable number of smaller nodules ( Fig. 3 ); nodules more numerous in some polygonal areas close to dorsal margins, nodules almost absent around j6. Dorsal shield with 19 pairs of setae, two pairs (S4, S5) displaced ventrally ( Fig. 2 ). Distance between the bases of j1 approximately double length of j1. Setae j2 and six pairs of opisthosomal setae (J3, Z3, J4, Z4, J5, S5) thick, long, pilose, with longitudinal ridges on setal stem ( Fig. 4 ); other dorsal setae short, most distally pilose, especially J1 and Z1. Shield with eight pairs of prominent pores, three pairs (idj5, idZ1, idJ3) small, the most posterior pair (gdZ3) largest. Shield also with small, shallow cicatrix-like areas with dentate margins ( Fig. 1 ).

Ventral idiosoma ( Fig. 2 ). Tritosternum with short base and a pair of fine smooth laciniae ( Fig. 7 ). Pre-sternal plates absent. Endopodal shields fused with sternal shield between coxae I and II but free between coxae III and IV, small endopodal sclerites present near posterior margin of coxa IV; a pair of small round pores present posterior to coxae IV. Exopodal shields fused lateral to coxae II–IV. Sternal shield ornamented with smooth lines in polygonal pattern, wider than long, length 70–74, width at narrowest point 105–110, anterior and posterior margins concave, with three pairs of smooth, pointed simple setae, pores inconspicuous. Metasternal shields free, with a pair of smooth simple setae. Genital shield wedge-shaped, with a pair of smooth simple setae, indistinct anteriorly, truncate posteriorly, length 119–125, basal width 150–153. Ventri-anal shield pentagonal, the antero-lateral angles sharply pointed, wider than long, length 142–158, anterior width 185–200, widest point 250–265, ornamented with weak transverse lines anteriorly, and with four pairs of smooth simple pre-anal setae. The fourth pre-anal setae inserted on the lateral margins of the shield, the single pair of pores located level with or slightly behind the fourth pair of pre-anal setae. Anal opening pyriform, anus length 23–25, width 18–19 posteriorly, with three simple circum-anal setae approaching to the length of anus. Para-anal setae are close to the base of the anus base, post-anal seta separated from anus. Separate metapodal plates absent. Peritremes well-developed, extending anteriorly around margin of dorsal shield. Stigmata situated lateral to coxa IV. Peritrematal shield fused with dorsal shield at level of coxa II, expanded behind stigma, extending beyond coxa IV, posterior to the level of anterior margin of ventri-anal shield, but not reaching the level of the first pair of pre-anal setae.

Gnathosoma . Hypostome ( Fig. 5 ) with six transverse rows of fine denticles, the anterior row curved, and three pairs of smooth hypostomatal setae: setal lengths h1 27, h2 6, h3 38, palpcoxal setae 23. Chelicera ( Fig. 6 ) dentate, fixed digit with three large and four small teeth in two longitudinal lines; movable digit length 58, with two prominent teeth. Corniculus length 29. Epistome ( Fig. 8 ) with three prongs branched at tip, central prong with three branches, lateral prongs with two or three branches and a few serrations on outer margin. Palp tarsal claw 3-tined ( Fig. 9 ).

Legs ( Figs. 10–18 ). Length of leg I ( Figs 10–12 ) 1140–1215 (tarsus 310–335), tarsus I with a pair of very long and whip-like terminal setae and a number of short associated setae, tarsal claw absent, lengths of sub-distal setae 21–26 and 130–140, length of the longest sub-distal seta of tarsus I approximately double the distance between the setal base and the distal end of tarsus I ( Fig. 12 ). Other legs ( Figs 13–18 ) much shorter and thicker, each bearing a pair of tarsal claws. Leg II 620–655, leg III 600–670, leg IV 690–745. All setae on the legs simple. Chaetotaxy: Leg I: coxa 0 0/1 0/1 0, trochanter 1 1/1 1/1 1, femur 2 1/1 3/2 2, genu 2 2/1 1/2 2, tibia 2 1/2 2/1 1; Leg II: coxa 0 0/1 0/1 0, trochanter 2 0/1 0/1 1, femur 2 2/3 2/1 0, genu 1 1/1 3/1 0, tibia 1 1/2 1/1 1; Leg III: coxa 0 0/1 0/1 0, trochanter 1 1/1 0/1 0, femur 0 1/1 2/0 2, genu 0 1/1 2/1 2, tibia 1 1/1 1/1 2; Leg IV: coxa 0 0/1 0/0 0 0, trochanter 1 1/ 1 1/1 0, femur 1 0/1 2/0 2, genu 0 1/1 2/0 2, tibia 1 1/1 1/0 2. TarsusIV with three long thick postero-lateral setae ( Fig. 17 ).

Etymology. The specific name is derived from the type locality, Tibet Autonomous Region, China.

Remarks. The new species resembles eight related species: P. catenum , P. catenulum , P. tsushimanum , P. sibiricum , P. aokii , P. changchunense , P. tianmonum and P. jianfenglingense . They can be easily distinguished from each other by the characters shown in Table 1.

Figures

FIGURE 19. Podocinum tibetensis sp. n. Adult female: dorsal view. Scale represents 200 μm.

FIGURES 1 – 4. Podocinum tibetensis sp. n. Adult female: 1. Dorsal shield; 2. ventral idiosoma; 3. Part of the polygonal network; 4. Dorsal seta (Z 3). Scale represents 100 μm for 1, 2, 25 μm for 3, and 50 μm for 4.

FIGURES 5 – 9. Podocinum tibetensis sp. n. Adult female: 5. hypostome; 6. chelicera; 7. tritosternum; 8. epistome; 9. right palp, ventral view. Scale represents 50 μm for 5, 6, 7, 8; 100 μm for 9.

FIGURES 10 – 18. Podocinum tibetensis sp. n. Adult female, dorsal view of leg I – IV: 10. coxa I—trochanter I—femur I; 11. genu I – tibia I; 12. tarsus I; 13. tarsus II; 14. trochanter II – tibia II; 15. tarsus III; 16. trochanter III – tibia III; 17. tarsus IV; 18. trochanter IV – tibia IV. Scale represents 100 μm.