Pseudachorutes polychaetosus Gao & Palacios-Vargas, 2008

Babenko, Anatoly, Kuznetsova, Natalia, Nakamori, Taizo & Shveenkova, Yulia, 2021, A review of Pseudachorutes Tullberg, 1871 (Collembola, Neanuridae) from the East Asia, with description of six new species, Zootaxa 4938 (4), pp. 351-391 : 383-388

Pseudachorutes polychaetosus Gao & Palacios-Vargas, 2008

Figs 90–93 , 95–96 , Table 1

Examined material. Japan: 1 male, Honshu Island, Nagano Prefecture, E Chino city, Kitayama, surroundings of Mugikusa Hutte, 36°4.13’N 138°20.3’E, 2280 m alt., mixed forest with old trees ( Betula , Abies ) on steep slope, litter, 11 August 2016. M. Potapov & N. Kuznetsova leg.

Main diagnostic characters: Large-sized species with long differentiated setae and strongly elongated buccal cone. Labrum with 4 prelabral and 11(12) labral setae. Main part of labium with 3 proximal setae and seta L, basomedial part of labium (submentum) with 3 setae (f—absent), its basolateral part (mentum) with 4 setae, perilabial area with 4 setae. Head with both a0 and d0, Th. I with 4 or more setae on each side, all other terga with many extra setae, even subterga between thoracic terga sometimes with few setae. Mucro with basal «swelling». Male genital plate with 5+5 spine-like setae, two groups of modified setae also present at base of furca. Each anal valve with 3 hr-setae.

Remarks. Pseudachorutes polychaetosus is a member of the longisetis -group (see above) and can be easily distinguished from all known species of the group not only by stronger plurichaetosis and the presence of modified setae on the base of furca and on the genital orifice but also due to narrow, strongly elongated buccal cone (cf. Fig. 92 & Fig. 94 ). It was described from the Lishan Mountains in northwest China, at a distance of more than 2700 km from the place in Japan where we found a very similar form. The status of the latter is not certain despite many unique characters that it shares with the types of P. polychaetosus . This specimen ( Fig. 95–96 ) is almost three times larger than specimens from the type series (2.96 mm vs 0.95–1.13 mm) and has more extra setae ( Figs 90–91 ), including the presence of setae on subterga between both Th. I–II and Th. II–III (setae in such position are developed only in one from three type specimens). A higher number of setae are also present in proximal parts of all legs: upper subcoxae– –3–4, 6, 6 setae vs 1, 3, 3; lower subcoxae– –0, 7, 5–8 vs 0, 3, 3, coxae 3, 8–9, 7–8 vs 3, 7, 7 and femora with usual number of 13, 12, 11 setae vs 12, 12, 11 in the types. In accordance with larger size of the Japanese specimen, its setae are also much longer: macrosetae up to 0.25 mm (vs 0.1 mm in the types), sensilla up to 0.088 mm (vs 0.03 in the types). There are also several other differences. PAO has more vesicles (14–16 vs 10 in the types). Ventral side of Ant. IV with more short sensilliform setae (~80 vs 30 in the types) which are usually truncate or clavate but not pointed as in the types. Labrum with more usual number of setae (4/12 [23322] vs 4/ 11 in the types).

Despite all these differences, most of which are probably related to the difference in size, we believe that Chinese and Japanese specimens may be conspecific but this assumption obviously needs further confirmation.

Distribution. China, Japan.

Figures

FIGURES 90–94. Pseudachorutes polychaetosus Gao & Palacios-Vargas (90–93) and P. longisetis Yosii (94): 90, chaetotaxy of head and Th. I–III; 91, chaetotaxy of Abd. III–VI; 92, labium; 93, tip of macroseta; 94, labium. Scales: Figs 90–91 = 0.1 mm, 92–94 = 0.01 mm.

FIGURES 95–96. Pseudachorutes polychaetosus Gao & Palacios-Vargas. General appearance. 95, dorsal view; 96, lateral view.