Nipponentomon bidentatum Nakamura, 2004, new record to Chinese fauna

Figs. 76–84, Tables 2, 5

Material examined. One female (no. HBBH-8-4), 2 males (no. HBBH-8-1, HBBH-8-5), collected in broad-leaved forest of Honghe Nature Reserve, Tongjiang City, Heilongjiang Province, China, 47°44'16'' N 133°36'47'' E, 53 m elev., 15 August 2009, collected by D. H. Wu. 1 female (no. SQTT-7), 1 maturus junior (no. SQTT-8), collected in marsh sedge composed by Carex meyeriana, Honghe town, Tongjiang City, Heilongjiang Province, China, 47°35'27'' N 133°38'38'' E, 56 m elev., 15 August 2010, collected by D. H. Wu. Specimens are deposited at SEM and NEIGAE.

Description (Chinese specimens). Adult body length 1320–1400 µm (n=4). Head elliptic, length 160–165 µm, width 120–130 µm. Labrum short and round. Setae sd4 and sd5 short and sensilliform, seta d6 absent. Posterior margin of head with seta d7 and sd7 subequal in the length, d7 about 21–23 μm, sd7 about 24–25 μm, l5 about 8 μm. Clypeal pore cp and frontal pore fp present (Fig. 76). Pseudoculus length 7 μm, PR=23 (Fig. 77). Maxillary gland large, calyx with lateral racemose appendices and one helmet-like dorsal appendix, and bilobed posterior dilation. Posterior dilation of maxillary gland length 30–35 μm, CF=5.3–6.4 (Fig. 78). Maxillary palpus with two setiform sensilla (Fig. 79). Labial palpus well developed, with one sausage-like sensillum (Fig. 80).

Foretarsal length 100–105 µm, claw length 40–45 µm, TR =2.3–2.5; empodium length 6–7 µm, EU=0.13–0.18. Dorsal sensillum t1 filiform, t2 slender and long, t3 leaf-like, BS=0.69–0.72. 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 surpassing base of g, sensillum g filiform and reaching base of claw. Interior sensillum a' broad, b' absent, c' broad at base and extremely long (Figs. 81, 82). Relative length of sensilla: t3 <t1<(e = g) <b <c <(a = a') <d <t2<c' <f. Setae β 1 and δ 4 setiform. Claw with two inner teeth. Length of middle tarsus 50–55 µm, claw length 23–25 µm. Length of hind tarsus 55–60 µm, claw length 25–30 µm.

Adult chaetotaxy given in Table 5. Length ratio of pronotal setae 1: 2 as 2.5:1, 42–43 μm and 17–19 μm, respectively. Seta M on mesonotum and metanotum 18–19 μm and 20–21 μm long, respectively. Length ratio of P1: P1a: P2 on mesonotum as 4.5–5.0: 1: 5.5–6.3, 43–45 μm, 7–8 μm, and 51–56 μm, respectively. Setae A2 and M2 on prosternum, A2 on mesosternum and metasternum sensilliform.

Dorsal Ven t ral Segment Formula Setae Formula Setae Tergite I with four pairs of A-setae, P1a and P2a sensilliform. Tergite VII with eight pairs of porterior setae, P1a present. Sternites IV–VI with 5/8 chaetotaxy. Tergite and sternite of abdominal segment VIII each with two irregular rows of small, scattered granules. Hind margin of tergite IX with small teeth in middle part. Hind margin of tergites X–XI with distinct but short ciliation. Hind margin of sternites IX–XI smooth. Hind margin of tergite XII smooth, sternite with delicate serration.

Body porotaxy given in Table 2. Pronotum without pores, mesonotum and metanotum with pores sl and al. Prosternum without pores, mesosternum and metasternum each with single median pore situated anterior to level of setae M. Tergite I with pores psm. Tergites II–VII with pores psm, psl and al. Pore psm on tergite VIII with several surrounding teeth. Tergites IX–XI without pores, XII with single median pore. Sternites I–VII each with single median pore, situated in posterior part, close to setae P 1 in I–VI, and close to Pc in VII. Sternites VIII–XI without pores. Sternite XII with 1+1 anterolateral pores.

Subapical and apical seta of second and third appendages nearly equal in length. Striate band on abdominal segment VIII well developed. Comb on abdomen VIII rectangular, with 11 distinct teeth (Fig. 83). Female squama genitalis with short, blunt acrostyli (Fig. 84).

Chaetal variability. Adult (n=4): on metanotum, asymmetrical absence of M (1 specimen); on sternite III, symmetrical presence of A1 and absence of Ac (1); on sternite IV, absence of Ac (3); on sternite VI, absence of Ac (1); on sternite VII, absence of Ac (1); on sternite VIII, presence of Pc (1).

Distribution. China (Heilongjiang); Russia (Far East, Khabarovsk).

Diagnosis. Nipponentomon bidentatum Nakamura, 2004 is characterized by the foretarsal claw with two inner teeth, short labrum, extremely long sensilla f and c', setiform seta β 1 and δ 4, and absence of seta d6 on the head. Remarks. In the original description of N. bidentatum Nakamura, 2004, the head chaetotaxy, length of setae on the body, and porotaxy were not described in detail, probably due to the limited specimens available (two). We supplement those missing data and give a complete description based on Chinese specimens in the present paper. Chinese specimens are longer (maximum 1400 μm) than the Russian specimens (maximum 1241 μm).