Entomobrya amurica

Ecology. The new species was recorded in mass occurrence on a sandy river bank.

Description. Body length (excluding antennae) 1.95 mm (Holotype); mean for n = 4: 2,07 mm. Ground colour white or very pale, with pigment as antennae darker than the body, three longitudinal stripes on the frontal head, five on Th II – Abd II, seven longitudinal or obliques on Abd III, irregular patches on Abd IV, and final area on Abd VI (Fig. 2 A). Head. Eight eyes, GH slightly smaller than EF (Fig. 3 A). Antennae length 1.28 mm, 3.18 times the length of the head (n = 4); Ant IV with bilobed apical vesicle and pin chaeta present; subapical organite very small; sensory organ of Ant III with the special sensilla long-ovoidal, and three guard additional sensilla; relative length of Ant I / II / III / IV = 1 / 1.25 / 1.01 / 1.15 (n = 4). Prelabral chaetae ciliated. Labral papillae smooth, but triangular in shape. Lateral process of labial papilla E just reaching its apex. Maxillary palp bifurcate, with three sublobal chaetae. Body. Length ratio of Abd IV / III = 6.7 (n = 4). Trochanteral organ with approximately 15 chaetae. Tibiotarsus not sub-segmented, without smooth chaetae, except for a smooth terminal chaeta on leg III. Claw with four inner teeth: paired at 55 % and first unpaired at 80 % from the basis, second unpaired tooth subapical; unpaired dorsal tooth basal (Fig. 3 E). Empodium lanceolate, with slightly serrated external lamella (pe) in leg III. Tenent hair clavate, longer than the claw. Length of manubrium and dens 0.40 and 0.52 mm, respectively (n = 1). Manubrial plate with four chaetae and two pseudopores. Mucro with teeth similar in size, mucronal spine reaching the tip of the subapical tooth; area not crenulated of dens two times the length of mucro. Macrochaetotaxy (Figs 3 A – D). Simplified Mc formula: 4 - 1 - 0 - 3 - 2 / 3 - 4 / 2 - 4 (3) / 0 - 2 - 1 / 0 (4) - 3 - 1 0 4 - 1 0 3 - 4 (5). Head: H 1 area with Mc An 2, An 3 a 1, An 3, and one additional chaeta; H 2 area with Mc A 5; H 4 area with three Mc (S 1, S 3, and S 4 i); H 4 ’ area with three Mc (S 5, S 5 i, and S 4); H 5 area with Ps 2 and Ps 5 Mc. Mesothorax: area T 1 with three Mc (m 1, m 2, and m 2 i); T 2 with four Mc (a 5, m 4, m 4 p, and m 5). Abdomen: Abd II area A 1 with two Mc (a 2 and a 3), area A 2 with four Mc (m 3, m 3 e, m 3 ep, and m 3 eai 2; in one specimen m 3 eai 2 absent); Abd III without Mc on A 3, two Mc on areas A 4 (a 2 and a 3) and one on A 5 (m 3), “ as sensilla present; Abd IV with or without Mc on A 6 area: if present up to four with asymmetric disposition; three Mc on A 7 (A e 3, B 3 and C 1); an unpaired Mc (A 04) and another four on A 8 (A 4, A e 4, B 4 and C 2 a); A 9 with an unpaired Mc (A 05) and three Mc (A 5, A e 5 pp and A i 1); the psp can be at a different location in the same specimen; A 10 with four or five Mc (A i 2, A 6, Ae 7, Ae 8, and B 6); sensillar formula from Th II to Abd V normal as in the rest of Entomobryinae (Zhang & Deharveng 2015): 2,2 / 1,2,2,7 - n, 3; microsensillar formula from Th. II to Abd III: 1,0 / 1,0,1.

Figs 2 A, 3 A – E

Diagnosis. The unequivocal identification of the species can only be done using the abbreviated formula of head (H 1 – 5 areas), Th II (T 1 – 2 areas), Abd II (A 1 – 2 areas), Abd III (A 3 – 5 areas), and Abd IV (A 6 – 10 areas) Mc, sensu Jordana & Baquero (2005), as: 4 - 1 - 0 - 3 - 2 / 3 - 4 / 2 - 4 (3) / 0 - 2 - 1 / 0 (4) - 3 - 1 0 4 - 1 0 3 - 4 (5).

Remarks. Ten species share with the new species the dorsal macrochaetotaxy of Abd II and III: E. erratica Brown, 1932; E. karlstetterae Baquero & Jordana, 2008; E. koreana Yosii, 1965; E. monopunctata Lee & Park, 1984; E. nana Lee & Park, 1992; E. oleniensis (Tshelnokov, 1987); E. regularis Stach, 1963; E. tokunagai Yosii, 1942; E. vigintiseta Lee & Park, 1984; and E. bicincta Jordana & Baquero sp. nov. (see below). From all of them, E. amurica sp. nov. can be separated for the presence of unpaired Mc on Abd IV (area A 8). From E. monopunctata and E. tokunagai, there is no information about the chaetotaxy of Th II, but they are different in the Mc of Abd IV: 0 - 2 - 1 - 2 - 2 for E. monopunctata and 1 - 3 - 2 - 2 - 2 for E. tokunagai. The only species with the same macrochaetotaxy on T 1 and T 2 on Th II is E. erratica. The remaining have 0 – 2 (E. karlstetterae), 4 – 4 (E. koreana), 3 – 2 (E. nana), 4 – 4 (5) (E. oleniensis), 2 – 4 (E. regularis), 4 – 5 (E. vigintiseta) and 3 – 5 (E. bicincta sp. nov.). E. erratica has 0 – 0 – 3 – 2 – 2 dorsal Mc on Abd IV. The differences in dorsal macrochaetotaxy (reduced formula of Jordana & Baquero 2005) for all these species are shown in the Table 1.

Etymology. The specific epithet refers to the Amur River, the largest river of the Far East of Russia.

Type material. Holotype: female on a slide, RUSSIA, Amurskaya Region, Blagoveschensk, sandy bank of Zeya River, on the sand in turf, (50.277257, 127.571377, 117 m a. s. l.), 24. iv. 2018, hand collection, cod. AO 2014 - 41 R- 01. Paratypes (same data as Holotype): 2 on a slide (AO 2014 - 41 R- 02 and 03), and 19 specimens in ethyl alcohol (AO 2014 - 41 R- 04 to 22). Kuznetsova, N. and Potapov, M. leg. Additional material. RUSSIA, Amurskaya Region, Arkhara, under bark of dead willow (coordinates 49.44424, 130.08451, 145 m a. s. l.), 17. viii. 2014, hand collection, 1 female on a slide (AO 2014 - 1 R- 01), Kuznetsova, N. and Potapov, M. leg.