Pseudachorutes andrei Weiner & Najt, 1985

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 : 370-373

Pseudachorutes andrei Weiner & Najt, 1985

Figs 61–65 , Table 1

Pseudachorutes sibiricus Rusek, 1991 , syn. nov.

Examined material. Russia: 1 juvenile, Far East, Southern Primor’e, Ussuri State Nature Reserve , Anikin River valley , broadleaf forest (walnut, ash, poplar, etc.) with Pinus sibiricus , 43°40.1’N 132°29.92’E, ~ 150 m alt., 13 August 2017. N. Kuznetsova, A. Kuprin & A. Geraskina leg. ; 2 males and 1 female, same region, «Kedrovaya Pad» State Nature Reserve , mixed coniferous-broadleaf forest, 43°6.95’N 131°30.42’ E, ~ 100 m alt., 29 July 2016. N. Kuznetsova & M. Potapov leg. ; 1 male and 1 juvenile, same Nature Reserve and forest type, but 43°6.88’N 131°29.23’ E, ~ 120 m alt.,, 27 July 2016. N. Kuznetsova & M. Potapov leg. ; 1 male and 1 juvenile, same region, but Sikhote-Alin State Nature Reserve, Brusnichnaya River , mixed (cedar, poplar, spruce, elm, white fir, birch, etc.) forest in valley, 45°38.9’N 137°0.58’E, ~ 200 m alt., 6 August 2017. N. Kuznetsova, A. Kuprin & A. Geraskina leg. ; 6 juveniles, Khabarovsk Territory, Komsomolsk State Nature Reserve, Gorin River , mixed coniferous-broadleaf forest, rotting wood, 50°44.25’N 137°25.43’E, ~ 250 m alt., 10 August 2018. N. Kuznetsova, A. Kuprin & A. Geraskina leg. ; 1 female, same region, but Anyuinski National Park, Tormasu River , mixed coniferous-broadleaf forest, rotting wood, 49°18.2’N 137°34.2’E, ~ 200 m alt., 07 August 2018. N. Kuznetsova, A. Kuprin & A. Geraskina leg. ; 1 juvenile, same region, Skotovski District, Falaza Mt. , 43°7.11’N, 132°47.53’E, ~ 500 m alt., moss on stones over stream, 08 September 2018. M. Potapov & A. Kuprin leg. ; 1 female and 4 males, Khabarovsk Territory, Komsomolsk State Nature Reserve , mixed forest with predominance of coniferous trees, Cornus canadensis association, 50°43.72’N, 137°23.52’E, ~ 100 m alt., pit-traps, 3–11 August 2018, O. V. Kuberskaya leg. ; 1 juvenile, Khabarovsk Territory , Komsomolsk-on-Amur—Khabarovsk route, broad-leaved herbaceous forest in valley, 48°51.17’N, 135°56.95’E, ~ 80 m alt., under bark, 13 August 2018, N. Kuznetsova, A. Kuprin & A. Geraskina leg.

Japan: 1 female, Honshu Island, Nagano Prefecture, E Chino city, Kitayama, surroundings of Mugikusa Hutte, 36°2.42’N 138°22.1’E, ~ 2250 m alt., coniferous forest ( Tsuga , Abies , Betula ), litter, 10 August 2016; 1 female, same area, 36°3.28’N 138°21.33’E, ~ 2100 m alt., plant association with Juniperus , Rhododendron and Pinus , litter and moss under Juniperus , 10 August 2016; 1 female and 1 male, same area, but 36°3.27’N 138°19.8’E, ~ 2000 m alt., humid forest with old trees ( Abies ), rotten wood, 12 August 2016; 2 males, Hokkaido Island, Shiretoko Peninsula, 44°3.7’N 145°5.48’E, ~ 600 m alt., mixed forest ( Betula ermanii , Alnus viridis , Abies sakhalinensis ), litter under birch, 17 August 2016; 2 females and 1 male, same Island, Tofutsu Lakes (west shore), sandy beach, litter under Rosa on dunes, 18 August 2016. All M. Potapov & N. Kuznetsova leg.

Main diagnostic characters. Large species with short buccal cone. Labrum with 4/2334 setae, labium with full number of setae (12), L absent, perilabial area with 5 setae. Head with both a0 and d0 and usually with some additional setae between eyes, Th. II with a2, Th. II–III with 4(5) ordinary setae (a3, a4, m4 and p4, sometimes also m3) additionally to S in dorso-external group, Abd. I–III usually with three ordinary setae (a3, m3, m4) in front of p3 and p4 (= S). Mucro with long lateral lamella almost reaching tip. Each anal valve with 2 hr-setae.

Description of specimens from Russia and Japan. Large species with expanded and slightly flattened body ( Fig. 61, 65 ), length (without antennae) up to 3.3 mm [1.75–1.85 mm according to original description], mature specimens from 1.4 mm. Colour dark, almost black. Tegument granulation uniform.

Antennae slightly shorter than head, Ant. III–IV fused dorsally, ventral separation well marked. Ant. IV ( Fig. 62 ) with typical trilobed apical vesicle, external ms, subapical or and seta i present; dorsal side of Ant. IV with six long differentiated sensilla (S1–S4, S7–S8), ventral side with only few short sensilliform setae. Antennal organ of Ant. III typical, inner sensilla small, sgv subequal or only slightly longer than sgd, ventral ms present. Ant. I–II with usual 7 and 12 setae, respectively.

Head with 8+8 subequal ocelli. PAO large, rounded, consisting of 12–24 densely packed vesicles ( Fig. 63 ), about twice size of nearest ocellus B, ratio 2.0–2.2: 1. Buccal cone rather short. Maxilla styliform with two tiny apical teeth and needle-like lamella, mandibles with two strong teeth, small additional tooth usually visible subapically ( Fig. 64 ). Distal edge of labrum rounded, number of labral setae as follows: 4/2334. Main part of labium with four proximal ordinary setae, seta L and labial organites invisible; submentum and mentum with usual 4+4 setae. Perilabial area with 5+5 setae.

Dorsal setae short and fine, sensilla 3.0–5.0 times longer than ordinary setae (even longer in juveniles), their number as usual, i.e. 22/11111. Typical pattern of dorsal chaetotaxy as in Fig. 61 , but asymmetric abnormalities quite common. Main characteristics: head with both unpaired a0 and d0, interocular area usually with few extra setae. Th. I with 4+4 setae. Only Th. II with a2-setae and ms, dorso-external group on both Th. II–III with 3–4 setae (a3–a4, m3–m4) in front of p3–p4, m3 on Th. II often absent, on Th. III absent only occasionally. Abd. I–III with 2–3 setae (a3, m3–m4) in front of p3–p4, one of m-setae frequently absent. Abd. V without p2 as usual.

Thoracic sterna without setae. Ventral tube with 4+4(5) setae, no seta on sternum of Abd. I, Abd. II with (4)5+5 ventral setae, Abd. III with 7–8(9) setae. Tenaculum with 3+3 teeth as usual. Furca and dens in particular quite short. Manubrium with 8–9+8–9 setae on main part, (4)5 setae on each basolateral lobe and 2 basal setae in line. Dorsal side of dens with six setae and uniform coarse granulation, hyaline field on its ventral side large. Mucro about as long as 1/3 dens, with long lateral lamella almost reaching tip. Each anal valve with two tiny hr-setae.

Legs I–III with 1, 2, 2 setae on upper subcoxae, 0, 2, 2 setae on lower subcoxae, 3, 7(8), 8 setae on coxae, 6, 6, 6 on trochanters, 13, 12, 10–11 setae on femora and 19, 19, 18 setae on tibiotarsi. Unguis rather short and wide with clear tooth in lower half of inner edge, lateral teeth invisible.

Remarks. The attribution of this form to P. andrei , originally found in North Korea, has a somewhat arbitrary character although it almost fully fits the original description. Unfortunately, Weiner & Najt (1985) did not describe chaetotaxy of P. andrei , just said that it is « classique, n’est pas figurée » and up to now it has been only known that dorsal sensilla in this species are 3.5–4.0 times longer than ordinary setae and there are 4+4 setae on Th. I (see Remarks to P. wandae Gao, Yin & Palacios-Vargas, 2008, p. 352 ). Fortunately the types of P. andrei are still available for examination (ISEA, Poland) which has been done by W.M. Weiner at our request. This study showed that the dorsal chaetotaxy of the Korean types is slightly less complete than in the specimens studied by us, although it is within the range of variations characteristic of the latter. Thus, setae m3 are absent on Th. II–III in the types whereas it usually present in our specimens, at least on Th. III. The types of P. andrei also lack setae m4 on Abd. I–III. Small differences are also observed in the ventral chaetotaxy and in the number of setae on leg segments. Nevertheless, all this does not go beyond the usual variations inherent in many species. Seven dorsal sensilla on Ant. IV mentioned in the original description proved to be a mistake. Of course, the existence of several similar species in the region cannot be ruled out, but in practice it is very difficult to distinguish between Siberian–Far Eastern and Korean individuals. As a result, we currently prefer to regard them as conspecific.

There is highly possible that this very form was described as P. cf. subcrassoides Mills, 1934 from Alaska by Fjellberg (1985) and was noted in the Eastern Palaearctic from northeastern Europe to Chukotka as P. sibiricus Rusek, 1991 by Babenko & Fjellberg (2006). The latter species, described on material from the vicinity of Lake Baikal, also has 4+4 setae on Th. I and labium with four proximal setae and without seta L. According to the original description the chaetotaxy of P. sibiricus is similar to that in our specimens being only slightly less complete which can be explained by the small size of the types (0.9 mm vs «up to 3.3» in our specimens). The same reason can probably explain other existing differences: only five sensilla on Ant. IV, 11 labral setae and the absence of extra setae in the interocular area. Some time ago, two specimens (paratypes?) from the type series received from J. Rusek have been studied by us. Unfortunately, both of them turned out to be juveniles, which did not allow adding much detail to the original description. Nevertheless, a high similarity between P. sibiricus and P. andrei is obvious and in our view the former may well be a junior synonym of P. andrei although additional studies of topotypic specimens of P. sibiricus are needed for certainness.

Distribution. This species, apparently, is the most widespread form of the genus Pseudachorutes in the eastern Palaearctic, with the Kanin Peninsula being the westernmost point of its range, and Alaska the most eastern.

Figures

FIGURES 61–65. Pseudachorutes andrei Weiner & Najt: 61, dorsal chaetotaxy; 62, Ant. III–IV (dorsal side); 63, PAO and nearest ocelli; 64, mandible; 65, general appearance. Scales: Figs 61–62, 65 = 0.1 mm, 63–64 = 0.01 mm.