Tetracanthella wui, Xie & Potapov & Sun, 2019

Xie, Zhijing, Potapov, Mikhail & Sun, Xin, 2019, Two new species of the genus Tetracanthella (Collembola; Isotomidae) from China, Zootaxa 4585 (3), pp. 573-580 : 578-580

Tetracanthella wui sp. nov.

Figs 2 , 12–20 , 22, 23

Type material. Holotype: female, China. Jilin province. Changbai Mts. , 141.75801°N 127.93890°E, 1700 m alt., 13.IX. 2015, 10 cm deep coniferous forest soil, leg. Donghui Wu; paratypes: 1 paratype collected on 15.V.2015 and 3 paratypes on 05.VIII.2009 from the same site . Holotype and 2 paratypes are deposited in Northeast Institute of Geography and Agroecology, CAS ( Changchun , China), 2 paratypes– –in Moscow State Pedagogical University (Moscow, Russia) .

Description. Body length about 1.6 mm (based on largest subadult male and female specimens). Body rather broad. Coloration spotty, dark. Antennae unpigmented, with dark tips ( Fig. 23 ). The largest polygons of cuticular reticulation subequal to mesochaeta socket ( Fig. 22 ). Canals between polygons well marked, smooth fields absent. Dorsal mesochaetae of medium size, not shortened in axial part of tergites, in posterior row of Abd. IV longer than on other parts of body (Md/p1 = 1.2–1.3). Abd. IV with p3 slightly longer than p1 (1.1–1.3). Macrochaetae middlesized and acuminate.

8+8 ocelli, G and H reduced (dcA: dcH = 1.5–2.0). PAO short, about 2.2–2.5 times longer than ocellus A. 4 prelabral chaetae. Outer maxillary lobe with 4 sublobal hairs and simple maxillary palp. Labium with complete set of guards [A(1)B(4)C(0)D(4)E(7)], papilla E with 7 guards (e7 present), 3 proximal and 4 basomedian chaetae. 4– 5+4–5 postlabial chaetae. Frontal chaeta ap present.

Axial chaetotaxy of body 12,8/6,6,6,6 ( Figs 15 , 18, 19 ). Macrochaetotaxy: 3(A),3(A)/3,3(5),3(5) (A: Mdl macrochaetae in anterior position). Abd. II and III with 2 additional macrochaetae on each side, these macrochaetae weakly developed on Abd. I. Corner mesochaetae on Th. II and III slightly stronger than other mesochaetae of prow. Number of s-chaetae: 3,3/2,2,2,2,4 (s), 1,1/1,1,1 (ms). S-chaetae of medium size, medial ones on Abd. I–III arranged lateral to Mdl macrochaetae. Sternite of Th. III without chaetae.

Coxa I without an external chaeta. Tibiotarsi with 1,2,2 dorsal tenent hairs acuminate and ventral tenent hair hardly developed ( Fig. 20 ). Tibiotarsi I and II with 21 chaetae each, tibiotarsus III with 25–26 chaetae. Empodial appendage 0.6–0.7 of inner edge of claw in length. Ventral tube with 4 posterior chaetae. Retinaculum with 4+4 teeth and 1 chaeta. Anterior furcal subcoxa with 3–4 chaetae, posterior one with 6–10 chaetae. Manubrium with 9– 11+9–11 dorsal chaetae, including 3+3 on baso-lateral flaps ( Fig. 16 ). Mucro bidentate, compact. Dens with 1 anterior and 5 posterior chaetae ( Figs 16, 17 ), dens: claw III = 1.6–1.8. Manubrium: dens: mucro = 7.8–9.6: 4.0– 4.7: 1.

Anal spines parallel, small, on low and not sclerotised papillae. Medial mesochaetae (a1) of Abd. V slightly in front of medial macrochaetae (a2). Macrochaetae of Abd. VI stiff and set together forming a cluster ( Figs 13, 14 ). Males present.

Remarks. The new species belongs to the asiatic ' stebaevae ' group with 3,3,3 main macrochaetae on Abd. I– III, respectively. It resembles species having numerous chaetae on furca: T. czernovae Kutyreva, 1980 (south part of the Far East of Russia) and T. antoni Potapov, 1997 (East Siberia, Russia), with 6 and 5 chaetae on posterior side of dens, respectively. The new species differs from T. czernovae by fewer chaetae on anterior side of dens (1/5 vs. 2–3/6) and from T. antoni by more chaetae in axial group of Abd. I–III (6,6,6 vs. 4,4,4).

Distribution. It is known only from Changbai Mountain massive in northeast China.

Derivatio nominis. The species is named after Dr. Donghui Wu, whose scientific activity made considerable input to knowledge of fauna of Collembola of Changbai Mountains.

Figures

FIGURES 1–2. Appearance and macrochaetotaxy of Tetracanthella dorsoduplex sp. nov. (1), and T. wui sp. nov. (2)

FIGURES 12–17. T. wui sp. nov.: 12, position of macrochaetae, s-chaetae and ms-chaetae on thorax and abdomen; 13, Abd. V–VI, lateral view; 14, cluster of stiff chaetae on Abd. VI, ventral view; 15, axial area of Abd. I–IV, dorsal view (axial chaetae marked); 16–17, furca, posterior (16) and lateral (17) views.

FIGURES 18–20. T. wui sp. nov.: 18–19, dorsal chaetotaxy of Th. III–Abd. II (18) and Abd. III–IV (19), 20, distal part of leg III in subadult female.

FIGURES 21–23. Reticulation of cuticle in Tetracanthella (21–22) and appearance of young individual of T. wui sp. nov. (23): 21, T. dorsoduplex sp. nov., Abd. V, area near external anal spines; 22, T. wui sp. nov., posterior edge of Abd. IV, axial part. p1, p1'––chaetae of p-row, ASp-e––external anal spines.