Entomobrya tristriata Ma & Chang, 2020

Chang, Yan, Pan, Zhixiang & Ma, Yitong, 2020, A new species of Entomobrya (Collembola: Entomobryidae) from the Northeast China and first record of Entomobryoides sotoadamesi, Zootaxa 4731 (3), pp. 335-346 : 336

Entomobrya tristriata Ma & Chang sp. nov.

Figs 1–2 , 5–21 , Table 1

Types. Holotype: 1 female on slide, China, Jilin Province, Baishan City, Fusong County, Xianren Bridge Town , 127°14’14”E, 42°10’35”N, in litter, 9 Aug. 2009, collection number 1117, by Yitong Ma with aspirator, deposited in Nantong University . Paratypes: 3 females on slides, same data as holotype . 1female on slide, the Gate of Changbai Mountain , 128°05’56”E, 41°48’06”N, in litter, 10 Aug. 2009, collection number 1119, by Yitong Ma with aspirator, deposited in Nantong University .

Description. Body length up to 2.44 mm. Ground colour pale yellowish. Blue pigment present on Ant. II–IV and sometimes Ant. I also with blue pigment. Eyepatches dark blue. Longitudinal blue stripe present on dorsal midline from Th. II–Abd. III and a pair of longitudinal blue stripes on lateral part from Th. II–Abd. III. In most specimens, blue pigment on lateral part of Abd. II & III not apparent. Abd. IV may with a pair of blue patches centrally and an irregular transverse blue stripe posteriorly ( Figs 1–2 ).

Head. Antenna 0.45–0.58 times as long as body. Antennal segments ratio as I: II: III: IV= 1.00: 1.60–1.67: 1.51–1.53: 1.83–1.93. Distal part of Ant. IV with many sensory chaetae, normal ciliate chaetae and apical bulb bilobed ( Fig. 5 ). Lateral process (l.p.) of labial palp short with tip not reaching apex of same papilla ( Fig. 6 ). Subapical chaeta of maxillary outer lobe subequal to apical one, 3 smooth hairs on sublobal plate ( Fig. 7 ). Labial chaetae M 1 M 2 REL 1 L 2, all ciliate; chaetae M 2, R 0.40–0.71, 0.44–0.90 as long as chaeta M 1 respectively ( Fig. 8 ). Labral chaetae 4/5, 5, 4, all smooth, labral papillae absent ( Fig. 9 ). Dorsal cephalic chaetotaxy with 4 antennal (An), 4 median (M) and 8 sutural (S) mac, 6–7 mac in Gr. II, interocular chaetae as p, s, t ( Fig. 10 ).

Thorax. Th. II with 4–5 (m1, m2, m2i, m2i2, m2e sometimes absent) medio-medial, 3 (m4, m4i, m4p, m4i rarely absent) medio-sublateral, m5 present, 28–30 posterior mac, 1 ms and 2 sens. Th. III with 37–40 mac and 2 sens ( Fig. 11 ). Trochanteral organ with about 70 chaetae ( Fig. 12 ). Inner differentiated chaetae of tibiotarsus moderately ciliate ( Fig. 13 ). Tenent hair subequal to inner side of unguis, with tip strongly clavate. Unguis with 4 inner teeth, basal pair located 0.47–0.56 distance from base of inner edge of unguis, distal unpaired two respectively at 0.69–0.76 and 0.86–0.90 distance from base. Unguiculus acuminate with outer edge serrate ( Fig. 14 ).

Abdomen. Abd. IV 4.33–7.02 times as Abd. III in length along dorsal midline. Abd. I with 10–13 (m2i, m2, m3, m4, m4p, a1, a1a, a2, a3, a5 always present, a2e, m4i and a5 sometimes present) mac, 1 ms and 1 sens; sens inner to ms. Abd. II with 6 (a2, m3e, m3ea, m3ep, m3, a3) central, 1 (m5) lateral mac and two sens. Abd. III with 3 (a2, a3, m3) central, 4 (am6, pm6, m7a, p6) lateral mac, 1 ms and 2 sens ( Fig. 15 ). Abd. IV with 15–17 (A1, A3, A4, A6, Ae5, Ae7, B1, B3, B4, B5, B6 plus 4 mac with uncertain homologies, C1 always present) central and 26–28 lateral mac ( Fig. 16 ). Abd. V with 3 sens ( Fig. 17 ). Ventral tube anterior and posterior faces not clearly seen, 6 smooth and 17 ciliate chaetae on each lateral flap ( Fig. 18 ). Manubrial plaque with 14–16 ciliate chaetae and 2–3 pseudopores on each side ( Fig. 19 ) and ventro-apical part of manubrium with 27–31 ciliate chaetae ( Fig. 20 ). Distal smooth part of dens about 0.82–1.50 times as long as mucro. Mucro bidentate with subapical tooth larger than the apical. Basal spine reaching apex of subapical tooth ( Fig. 21 ).

Etymology. The specific epithet refers to the three (from Latin “ tri ”) longitudinal stripes of pigment on dorsal body.

Remarks. Colour pattern is a valid tool for specific delimitation in Entomobrya ( Katz et al. 2015) . The new species is similar to E. sibirica Stach, 1963 and E. unostrigata Stach, 1930 in colour pattern and all of them have three longitudinal stripes of pigment on dorsal body, but their differences in chaetotaxy and other characters are great. In E. tristriata sp. nov., tip of lateral process of labial palp is not reaching apex of the same papilla, but in E. sibirica and E. unostrigata , it is reaching apex of the same papilla. In addition, in E. tristriata sp. nov., mac on central part of Abd. II, Abd. III and Abd. IV are 6, 3, 15–17 respectively, but in E. sibirica , 5, 2, 10 and in E. unostrigata 6, 2, 16 ( Table 1 ).

Figures

FIGURES 1–4. 1–2, Entomobrya tristriata sp. nov., habitus; 3–4, Entomobryoides sotoadamesi, habitus.

FIGURES 5–10. Entomobrya tristriata sp. nov. 5, apex of Ant. IV; 6, lateral process of labial papilla E; 7, maxillary outer lobe and sublobal plate; 8, labium; 9, prelabral and labral chaetae; 10, dorsal cephalic chaetotaxy. Scale bars: 5–9 = 20 µm; 10 = 50 µm.

FIGURES 11–14. Entomobrya tristriata sp. nov. 11, dorsal chaetotaxy of Th. II–III; 12, trochanteral organ; 13, inner tibiotarsus chaetae (arrows showing differentiated chaetae); 14, hind foot complex. Scale bars: 11 = 50 µm; 12–14 = 20 µm.

FIGURES 15–18. Entomobrya tristriata sp. nov. 15, dorsal chaetotaxy of Abd. I–III; 16, dorsal chaetotaxy of Abd. IV; 17, dorsal chaetotaxy of Abd. V; 18, lateral flap of ventral tube. Scale bars: 15–17 = 50 µm; 18 = 20 µm.

FIGURES 19–21. Entomobrya tristriata sp. nov. 19, manubrial plaque; 20, ventro-apical part of manubrium; 21, distal part of dens and mucro. Scale bars: 19–21 = 20 µm.