Nipponentomon imadatei Bu, Wu & Yin sp. nov.

(Figs. 1–29, Tables 1, 2)

Material examined. Holotype, male (no. HBLS-8-3) collected in broad-leaved forest of Honghe Nature Reserve, Tongjiang City, Heilongjiang Province, China, 47°45'08'' N 133°37'29'' E, 54 m elev., 15 August 2009, collected by D. H. Wu. Paratypes, 2 females (no. HBBH-8-2, HBLS-8-8), 3 males (no. HBLS-1-1, HBLS-8-1, HBLS-8-2), same data as holotype. The holotype and three paratypes are deposited in the Shanghai Entomological Museum (SEM), and two paratypes are kept at the Northeast Institute of Geography and Agroecology (NEIGAE), Changchun, China.

Description. Adult body length 1300–1400 µm (n = 6). Head elliptic, length 130–150 µm, width 95–110 µm. Labrum short and round. Setae sd4 and sd5 short and sensilliform, seta d6 present. Posterior margin of head with seta d7 and sd7 subequal in length, about 20–22 μm, l5 about 7–8 μm. Clypeal pore cp and frontal pore fp present (Fig. 1). Pseudoculus length 6–8 μm, PR= 19–25 (Fig. 2). Maxillary gland large, calyx with lateral racemose appendices and one helmet-like dorsal appendix, and bilobed posterior dilation. Posterior dilation of maxillary gland length 25–30 μm, CF=5.2–5.6 (Fig. 3). Maxillary palpus with two setiform sensilla (Fig. 4). Labial palpus well developed, with one short, sausage-like sensillum (Fig. 5).

Foretarsal length 85–95 µm, claw length 38–38 µm, TR = 2.4–2.7; empodium length 5–7 µm, EU = 0.13–0.18. Dorsal sensillum t1 filiform, t2 slender and long, t3 leaf-like, BS = 0.76. Exterior sensillum a slender, b and c filiform, c slightly longer than b, d and f broad at base and extremely long, e slender and short, g filiform and reaching base of claw. Interior sensillum a' broad, b' absent, and c' broad at base and extremely long, with its apex reaching middle of claw (Figs. 10, 11). Relative length of sensilla: t3 <(t1 = e) <b <c <(a = g = a') <(d = t2) <c' <f. Seta β 1 and δ 4 modified, short and sensilliform. Claw long and slender, with single inner tooth. Length of middle tarsus 45–50 µm, claw length 17–20 µm. Length of hind tarsus 50–55 µm, claw length 20–25 µm.

Adult chaetotaxy given in Table 1. Length ratio of pronotal setae 1: 2 as 2.1–2.3:1, 40–42 μm and 18–19 μm, respectively. Lengths of seta M on mesonotum and metanotum 17–20 μm and 24–26 μm, respectively. Setae P1a and P2a on mesonotum short and sensilliform, P5 pin-shaped. Length ratio of P1: P1a: P2 on mesonotum as 5.0–5.7: 1: 6.3–7.1, 41–43 μm, 6–7 μm, and 48–50 μm, respectively. P1a and P2a on metanotum short sensilliform, P5 minute (Fig. 6). Setae A2 and M2 on prosternum, A2 on mesosternum and metasternum sensilliform (Figs. 7–9).

Tergite I with P1a and P2a sensilliform (Fig. 12). Tergites II–VI with five pairs of anterior seta and eight pairs of posterior setae (Figs. 13, 18). Tergite VII with four pairs of anterior setae (A1 absent) and without P1a, P2a sensilliform (Fig. 14, 21). P1a on sternites I–III sensilliform (Figs. 15–17). Sternites IV–VI with 3/8 setae (Fig. 17); sternite VIII with 4/2 setae. Tergite and sternite of abdominal segment VIII each with two irregular rows of small and scattered granules. Hind margin of tergite IX smooth. Hind margin of tergites X–XI with distinct short ciliation. Hind margin of sternites IX–XI smooth. Hind margin of tergite XII smooth, sternite with delicate serration (Figs. 25, 26).

Body porotaxy given in Table 2. Pronotum without pores, mesonotum and metanotum with pores sl and al (Fig. 6). Prosternum without pores, mesosternum and metasternum each with single median pore situated anterior to level of setae M (Figs. 7–9).

Dorsal Ventral

Segment Formula Setae Formula Setae Tergite I with pores psm (Fig. 12). Tergites II–IV with pores psm and al (Fig. 13, 18), V–VII with pores psm, psl and al (Figs. 14, 19–21). Pore psm on tergite VIII with several surrounding teeth. Tergites IX–XI without pores, XII with single median pore (Fig. 25). Sternites I–VII each with single median pore, situated in posterior part, anterior to seta P1 on sternites I–VI, and anterior to seta Pc on sternite VII (Figs. 15–17). Sternites VIII–XI without pores. Sternite XII with 1+1 anterolateral pores al (Fig. 26).

Abdominal appendages typical of the genus, with 2, 1, 1 segments and 4, 2, 2 setae. Subapical and apical setae of second and third appendages nearly equal in length (Figs. 23, 24). Striate band on abdominal segment VIII well developed (Fig. 29). Comb on abdomen VIII rectangular, with 9–12 distinct teeth (Fig. 27).

Female squama genitalis with short blunt acrostyli (Fig. 28).

Chaetal variability. Adult: on metanotum, asymmetrical absence of A1 (1 specimen); on prosternum, asymmetrical absence of P3 (1); on metasternum, asymmetrical absence of A1 (2); on tergite I, asymmetrical absence of A2 (1); on tergite VI, asymmetrical absence of P1a (2); on tergite VIII, asymmetrical absence of A2 (1); on sternites IV–VI, symmetrical presence of A1 and absence of Ac (1); on sternite V, presence of two Ac (1).

Etymology. We dedicate this new species to the late Professor Gentaro Imadaté, the eminent taxonomist of Protura from Japan, for his great contribution to the knowledge of Protura from Japan and Southeast Asia.

Distribution. China (Heilongjiang).

Diagnosis. Nipponentomon imadatei sp. nov. is characterized by a short labrum, extremely long sensilla f and c' on the foretarsus, sensilliform β 1 and δ 4, absence of seta P1a on tergite VII, 8/12 setae on tergite I, 3/8 setae on sternites IV–VI.

Remarks. Nipponentomon imadatei sp. nov. is similar to Nipponentomon jaceki Shrubovych 2009 and N. khabarovskense Nakamura, 2004 from the Russian Far East in the length of several sensilla on the foretarsus and absence of P1a on tergite VII. It differs from N. jaceki in the length of sensillum e, which is short and just surpasses the base of sensillum f (long and surpassing base of sensillum g in N. jaceki), sensilliform seta β 1 on the foretarsus (setiform in N. jaceki), presence of seta A3 on tergite I (in N. jaceki seta A3 absent), presence of three A -setae on sternites IV–VI (five A -setae in N. jaceki), the shape of the comb (straight hind margin in N. imadatei sp. nov., concave hind margin in N. jaceki), and absence of ciliation on the hind margin of tergite IX (with distinct ciliation on hind margin of tergite IX in N. jaceki). It differs from N. khabarovskense in the length of sensillum e on foretarsus (short in N. imadatei sp. nov., long in N. khabarovskense), chaetotaxy of tergite I (seta A3 present in N. imadatei sp. nov., absent in N. khabarovskense), and chaetotaxy of sternites IV–VI (three A -setae in N. imadatei sp. nov., five in N. khabarovskense). It is also similar to N. pembertonense Bernard & Biechele 2008 from USA in having three A -setae on sternites IV–VI, but can be distinguished by the length of sensilla f and c' on foretarsus (extremely long in N. imadatei sp. nov., short in N. pembertonense), seta d6 on head (present in N. imadatei sp. nov., absent in N. pembertonense), and the chaetotaxy of tergites I, VII, VIII and sternite I (8/12, 8/14, 6/15 and 3/ 4 setae in N. imadatei sp. nov., 6/12, 8/16, 4/15 and 3/2 setae in N. pembertonense, respectively).

Nipponentomon taiga Shrubovych sp. nov. Figs. 30–52, Tables 2, 3

Material examined. Holotype female (slide no. 73.1) from a moss sample collected in peat and soil in a mixed forest near Turukhansk, 65°48' N 88°00' E, Evenkia, Krasnoyarskiy Kray, Siberia, Russia, 26 July 2003, coll. A. Babenko. Paratypes: 6 females (no. 73.2–73.6, 6615), collected together with the holotype. Other materials (not included in type series): 2 females, 1 maturus junior, 1 larva II (no. 73.7–73.9) from litter and soil sample from a birch-pine forest on the bank of the lake Teletskoe Ozero, near Artybash, 51°48' N 87°22' E, 10 September 1988, coll. S.K. Stebaeva; 4 females (no. 73.10–73.12, 6616) from litter and soil sample from a forest on the bank in pass on the Western Sayan Mountains, near Bolshoy On, 2000 m elev., 51°42' N 89°53' E, 8 August 1989, coll. S. Iordanskiy; 1 female (no. 73.13) from a litter and soil sample in a mixed forest on bank of the river Podkamennaya Tunguska, 61°70' N 90°63' E, Borskiy District, Krasnodarskiy Kray, Siberia, Russia, 1 August 2006, coll. M. Potapov. The holotype (no. 73.1), 4 paratypes, (no. 73.2–73.5) and other materials are deposited in the collection of the State Museum of Natural History of the National Academy of Sciences of Ukraine, L’viv (SMNH); 1 female (no. 73.6) in the collection of M. Potapov; 2 females (no. 6615 and 6616) in the collection of the Institute of Systematics and Evolution of Animals of the Polish Academy of Sciences (ISEA), Kraków, Poland.

Description. Adult body length 1300 µm (n = 7). Head length 175–180 µm. Dorsal side of head with modified seta sd5, setae l3 and sd4 not modified, slender, d6 absent (Fig. 30). Posterior margin of head with seta d7 and sd7 equal in length, 27–28 μm, l5 about 10–11 μm. Clypeal pore cp and frontal pore fp present. Labrum very short, rounded (Fig. 32). Pseudoculus broader than long, with short posterior extension, 9-10 µm, PR = 18–19 (Fig. 31). Maxillary gland with large, densely granulated calyx; posterior filament short, with simple posterior dilation, length 36–40 μm, CF = 4.5–5.0 (Fig. 33). Maxillary palpus short, dorsal and lateral sensilla equal in length, slender (Fig. 34). Labial palpus well developed, with broad basal sensillum (Fig. 35). Labium with small teeth on inner margin.

Foretarsus length 127–132 µm, lacking sensillum b'; sensillum t1 filiform; t3 leaf-like; d and f thin with narrowly rounded apex; other sensilla parallel-sided (Figs. 37, 38). Sensillum b thicker and slightly longer than c. Sensillum d located very close to short sensillum e. Sensillum a' located at the level of t2 insertion and reaching to base of seta α 6 (Fig. 36). Seta β 1 unmodified, setiform, longer than δ – setae, δ 4 sensilliform, short, thick and truncated apically (Fig. 36). Claw long and slender, length 38–40 µm, with one inner tooth. Empodial appendage short, 6–7 µm. Relative length of foretarsal sensilla: t3 <e <c <g <t1 <b <d <a' <(a = c') <t2 <f. BS = 0.8-0.9, TR = 3.0–3.4; EU = 0.2. Pores present near base of sensilla c and t3. Length of middle tarsus 60–65 µm, claw length 20–23 µm. Length of hind tarsus 70–75 µm, claw length 25–27 µm.

Adult chaetotaxy given in Table 3. Setae on nota differing distinctly in length (Fig. 39). Length ratio of pronotal setae 1: 2 as 1.4:1, 50–53 and 29–31µm, respectively. Seta M on mesonotum short and slender, on metanotum longer, 23 and 50 μm, respectively. Accessory setae P1a, P2a and P2a' modified, short, stumpy, truncated apically (Fig. 51); P3a and P4 subequal in length and shape, short, unmodified; P5 a small sensillum. Length ratio of P1: P1a: P2 on mesonotum as 7.6-7:1:9, 55–58 μm, 5–7 μm, and 67–73 µm, respectively. Prosternum with seta M2, mesosternum and metasternum without A1 setae (Figs. 44, 45). Setae A2 and M2 on prosternum and A2 on mesosternum and metasternum short, setiform.

Dorsal Ventral Accessory setae on tergites I–VI similar to those on nota, short and stumpy (Fig. 51). On tergite VII accessory seta P1a not modified, setiform, setae P2a and P4a stumpy and shorter (11 and 6 μm, respectively). Tergites V–VII anteriorly with two parallel cuticular lines connected dorsally by short convergent lines. Tergites II–IV with one anterior line only. Accessory setae on sternites I–VII unmodified, setiform, their length about 16-17 μm (Fig. 51). Sternites VI–VII anteriorly with two parallel cuticular lines as on the tergites. Sternite V with one anterior cuticular line.

Seta 1a on tergite IX slightly shorter than seta 1. Seta 2a on tergites IX and X shorter than remaining setae (Figs. 42, 43). Lateral part of tergites IX–XI with distinct ciliated lines (Fig. 42). Hind margin of tergites X–XI with distinct ciliation (Fig. 43). Hind margin of sternites IX–X smooth in middle part, with distinct small teeth laterally.

Body porotaxy given in Table 2. Mesonotum and metanototum with pores al and sl. Prosternum lacking pores; mesosternum and metasternum usually with two close adjacent median pores (Fig. 45).

Pores psm present on tergites I–VI, psl absent on tergites I-VII, al present on tergites II–VII (Figs. 40, 41). Tergite VII without psm pores. Sternite I without pores (Fig. 46), sternite II with single median pore, sternites III–VI with two median pores, situated in central part, and sternite VII with one central pore (Figs. 47, 48). Pore psm on tergite VIII with several surrounding teeth. Tergite XII with single median pore (Fig. 43), sternite with 1+1 anterolateral pores (Fig. 49). Posterior margin of tergite XII smooth, sternite with delicate serration in central part.

Abdominal appendages with 4, 2, 2 setae. Subapical seta of abdominal appendages II and III slightly longer than apical seta, 25–27 and 17–18 μm, respectively (Fig. 47).

Abdominal segment VIII with distinct striate band and with two irregular, parallel rows of small scattered denticles anteriorly (Figs. 43, 49). Comb VIII composed of 14–16 irregular teeth (Fig. 52). Posterior margin of sternite and laterotergites VIII smooth.

Male squama genitalis unknown. Female squama genitalis with long, pointed, bifurcated acrostyli (Fig. 50).

Chaetal variability. Chaetotaxic variability infrequent in the 7 females examined: mesonotum with asymmetrical absence of P1a ' (on 1 specimen), tergite I with asymmetrical absence of P0a (1); sternite III with 4 A- setae (2), sternite VII with Pc absent (1). In other material collected from eastern Siberia (7 females): tergite I with asymmetrical absence of P0a (6); sternite III with 4 A- setae (1), sternite VII with Pc absent (4).

Etymology. Nipponentomon taiga is named for the dominant biotope “ taiga ” in Siberia.

Distribution. Russia (Siberia).

Diagnosis. Nipponentomon taiga sp. nov. is characterized by a short labrum, absence of seta d6 on head, presence of setae P2a' on nota, P0a on tergite I and P1a on tergites I–VII, absence of seta P3a on tergites II–VII, and long, setiform foretarsal seta β 1.

Remarks. Nipponentomon taiga sp. nov. is similar to N. uenoi uenoi Imadaté & Yosii, 1959, N. uenoi paucisetosum Imadaté, 1965 and N. heterothrixi Yin & Xie, 1993 (Imadaté 1965, Imadaté &Yosii 1959, Yin & Xie 1993), in possessing accessory seta P2a' on the mesonotum and metanotum. The new species differs from these related species in the presence of a pair of accessory setae P0a and absence of seta A3 on tergite I, presence of 7 A - setae on metasternum (seta A1 absent in N. taiga sp. nov., other three species with 9 A -setae) and absence of seta d6 on head. Position, shape and length of foretarsal sensilla and setae are similar in all species analysed, with the exception of the shape of seta β 1 (setiform and longer in N. taiga sp. nov., sensilliform and shorter in the other species). Nipponentomon taiga sp. nov. differs from N. uenoi uenoi and N. uenoi paucisetosum in the absence of seta P3a on tergites II-VII and additionally from N. uenoi uenoi in the lack of seta P1a' on the nota and shorter foretarsal sensillum c (in N. uenoi uenoi sensillum c is longer than b).

The new species is most similar to N. heterothrixi in chaetotaxy. The two species differ in the shape of seta sd4 on the head (broadened in N. heterothrixi, setiform in N. taiga sp. nov.), shape of the accessory setae on tergites VI and VII (setiform in N. heterothrixi, sensilliform in N. taiga sp. nov. except for seta P1a on tergite VII), in the length of foretarsus and foretarsal sensilla (in N. heterothrixi the foretarsus is shorter and sensilla c, e, g, a' and c' are longer, than those in N. taiga sp. nov.), length of pronotal setae (seta length ratio half of that in N. heterothrixi), shape of the acrostyli (short and stumpy in N. heterothrixi, long and pointed in N. taiga sp. nov.) and in porotaxy (Table 2).