Acrotritia tibetensis, Liu, Dong & Chen, Jun, 2015

Liu, Dong & Chen, Jun, 2015, Acrotritia species (Acari: Oribatida: Euphthiracaridae) from China with description of a new species, Zootaxa 3937 (1), pp. 127-146 : 130-132

Acrotritia tibetensis sp. nov.

( Figs. 1 A–H)

Diagnosis. Entire surface distinctly foveolate; prodorsum with one pair of long lateral carinae, bifurcated at insertion level of lamellar setae; sensilla with flat and truncate head, covered with small spines; prodorsal and notogastral setae barbed in distal half, except exobothridial setae; vestigial setae f 1 positioned anterior to setae h 1; formula of genital setae: 8:1; tarsi of legs I bidactylous, tarsi II–IV heterotridactylous.

Description. Measurements. Holotype: prodorsum: length 285, width 215, height 94, setae: ss 100, ro 50, in 120, le 61, ex 10, mutual distance: in–in 90, le–le 50, ro–ro 32; notogaster: length 600, width 405, height 420; c 1 75, c 2 75, c 3 75, c p 75, d 1 70, d 2 65, e 1 85, e 2 70, h 1 97, h 2 65, h 3 74, ps 1 85, ps 2 75, ps 3 70, mutual distance: c 1– d 1 160, d 1– e 1 185, e 1– h 1 115, h 1– ps 1 105; genito-aggenital plate 225×70, ano-adanal plate 284×90. One paratype: prodorsum: length 305, width 235, height 115; notogaster: length 700, width 445, height 460.

Integument. Colour yellowish. Entire surface distinctly foveolate.

Prodorsum ( Figs. 1 A–C). One pair of strong lateral carinae present, with long forks at insertion level of lamellar setae; sensilla (ss) with narrow pedicel and flat, truncate head, covered with small spines; interlamellar setae (in) stout and erect, densely barbed in distal half; lamellar and rostral setae (le and ro) semi-erect and slightly thinner, sparsely barbed in distal half; comparative lengths: in–le/ ro–le≈ 1.2.

Notogaster ( Fig. 1 A). Notogastral setae fairly short (c 1/ c 1– d 1 ≈ 0.47), sparsely barbed in distal half; setae c 2 further away from anterior border than setae c 1 and c 3; vestigial setae f 1 positioned anterior to setae h 1; openings of the lateral opisthosomal glands and lyrifissures positioned typically.

Ventral region ( Figs. 1 A, D). 9 pairs of genital setae (g) arranged with formula: 8:1; 2 pairs of aggenital setae located longitudinally; anal, adanal setae (an and ad) and location of lyrifissures iad typical of genus.

Legs ( Figs. 1 E–H). Setal counts for leg segments: I: 1-3-4(2)-5(1)-17(3); II: 1-3-3(1)-4(1)-13(2), III: 2-2-3(1)- 3(1)-11, IV: 2-1-2-2(1)-10; tarsi of legs I bidactylous, tarsi II–IV heterotridactylous.

Material examined. Holotype: adult ( ZMCAS, in alcohol, CJ-01-89), Tibet, Nyalam, Zhangmu, Youyiqiao, 1850 m a.s.l., from litter under broad-leaved tree, 2 Sep. 2001, leg. Jun Chen. Paratypes: 1 adult ( ZMCAS, in alcohol, CJ-01-90), 1860 m a.s.l., other data same as holotype; 1 adult ( ZMCAS, in alcohol, CJ-01-64), Tibet, Bowo, Tangmai, from litter under shrub, 24 Aug. 2001, leg. Jun Chen; 1 adult ( ZMCAS, in alcohol, CJ-01-93), Tibet, Nyalam, Zhangmu, near customs, 2200 m a.s.l., from litter under broad-leaved tree, 2 Sep. 2001, leg. Jun Chen.

Etymology. The new specific name “ tibetensis ” refers to the type locality, Tibet.

Remarks. This new species is similar to Acrotritia vestita ( Berlese, 1913) , Acrotritia furcata ( Bayoumi & Mahunka, 1979) and Acrotritia koreensis ( Mahunka, 1997) with the presence of forked lateral carinae, but it differs from them by the following combination of features: 1) surface of body distinctly foveolate (versus punctate in A. vestita , and covered with polygonal sculpture in A. furcata and A. koreensis ); 2) prodorsum with long lateral carinae bifurcated at insertion level of lamellar setae, length of bifurcated part of lateral carinae/length of lateral carinae is about 0.65 (versus lateral carinae shorter and bifurcated anterior to insertion level of lamellar setae in A. vestita (0.5), A. furcata (0.47–0.57) and A. koreensis (0.36)); 3) lateral carinae bifurcated upward (versus downward in A. furcata and A. koreensis ); 4) sensilla with flat and truncate head (versus with slightly swollen head in A. vestita ) ( Niedbała 2011).

Compared with Acrotritia dikra ( Niedbała & Schatz, 1996) , this new species differs by the following features: 1) surface of body distinctly foveolate (versus punctate in A. dikra ); 2) sensilla with flat and truncate head (versus setiform); 3) one pair of genital setae in progenital position (versus two pairs).

Figures

FIGURE 1. Acrotritia tibetensis sp. nov.: A, lateral view of body (legs removed); B, prodorsum, dorsal view; C, sensillum, dorsal view; D, ventral plate; E – H, trochanter, femur, genu and tibia: E, leg I; F, leg II; G, leg III; H, leg IV. Scale bars: A, E – H = 100 µm; B – D = 75 µm.