Philotella porcella (Fjellberg, 1985) Babenko & Shveenkova & Potapov, 2022

Babenko, Anatoly, Shveenkova, Yulia & Potapov, Mikhail, 2022, New species of the genus Philotella Najt & Weiner, 1985 (Collembola, Neanuridae, Pseudachorutinae) from the Russian Far East, Zootaxa 5174 (5), pp. 525-550 : 545

Philotella porcella (Fjellberg, 1985) comb. nov.

Figs 49–55

Studied material: 1 female, Far East, Amur Region, ~ 3 km west of Arkhara ( Fig. 1 , point 2), broadleaf forest ( Quercus , Tilia , Betula , Ulmus ), litter, 17 August 2014, M. Potapov & N. Kuznetsova leg.; 1 male and 1 juvenile, Khabarovsk Territory, Komsomolsk State Nature Reserve, Gorin River ( Fig. 1 , point 12), mixed coniferous-broadleaf forest, 50°44.25’N 137°25.43’E, ~ 250 m alt., rotting wood, 10 August 2018. N. Kuznetsova, A. Kuprin & A. Geraskina leg.; 6 juveniles, same region, State Nature Reserve and collectors, Tormasu River ( Fig. 1 , point 13), mixed coniferous-broadleaf forest, litter, 49°18.2’N 137°34.2’E, ~ 200 m alt., 07 August 2018; 7 females, 2 males and 3 juveniles, Khabarovsk Territory, Lazo District, mountain range «Arseniev’s granites» ( Fig. 1 , point 11), valley of Malyi Katen River, ~ 500–600 m alt., mixed forest, litter and soil, 08 July 2019; 3 females, 2 males and 4 juveniles, same area, but ~ 900 m alt., forest belt, rotten wood, 08 July 2019; 3 females, 1 male and 3 juveniles, Southern Primorye, Partisan District, Mount Olkhovaya ( Fig. 1 , point 6), mixed forest in valley, 43°18.35’N 133°40.07’E, ~ 500 m alt., litter, 20 August 2018; 1 juvenile, same area, but 43°20.83’N 133°39.38’E, ~ 1600 m alt., P. pumila belt, soil, 20 August 2018. M. Potapov, Yu. Shveenkova & A. Kuprin leg.

Description. Length (without antennae) 0.5–0.8 mm. Colour dark blue, uniform dark. Tegument granulation strong, especially on abdominal tip.

Antennae clearly shorter than head, Ant. III–IV fused dorsally, ventral separation more or less clear. Ant. IV with slightly divided apical vesicle, external ms, subapical or and seta i present; six sensilla (S1–S4, S7–S8) on dorsal side of Ant. IV blunt and elongate ( Fig. 54 ), few sensilliform setae of various shape also present on its ventral side. Antennal organ of Ant. III typical, inner sensilla small, sgv longer than sgd and curved, ventral ms present.Ant. I–II with 7 and (11)12 setae, respectively.

Head with 5+5 small ocelli, about as large as secondary granules on ocular field. PAO usually rounded, more rarely slightly elliptic, consisting of 8–10 vesicles, its axis to ocellus B ratio as 1.8–2.0: 1 ( Fig 50 ). Buccal cone short and blunt. Maxilla styliform, lamellae not clearly seen. Mandible typical, with five teeth along cutting edge. Labrum with a common set of 4/2352 setae of different length, proximal pair of labral setae being the longest ( Fig. 51 ). Main part of labium of the first type with three ordinary setae in line and 2+2 axial setae between sensorial elements ( Fig.52 ); submentum and mentum with usual set of four setae each, i.e. 4+4. Perilabial area with 5+5 setae, 2+2 postlabial setae along ventral line present as usual.

Dorsal chaetotaxy usually symmetrical and rather reduced ( Fig. 49 ). Ordinary setae short, needle-like, sensilla longer, their number as usual: 22/11111, lateral ms present on Th. II. Main characteristics: head with unpaired seta d0 and only 2 setae on ocular field; Th. I usually with 2+2 setae, but variant with 3+3 setae also seen; only 2+2 axial (dorso-internal) setae present on all terga from Th. II to Abd. V; Th. II–III with only two setae additionally to p3 (=S) in dorso-external position, p3 set clearly in front of p4 on both thoracic terga; Abd. I–III with only one seta between axial group and sensillum p4; both Abd. IV–V with only 2+2 axial setae between sensilla.

Thoracic sterna without setae. Ventral tube with 4+4 setae, no seta on sternum of Abd. I, ventral side of Abd. II–III without unpaired axial setae. Furcal remnant in a form of two swellings, each with a seta, on anterior border of Abd. IV ( Fig. 55 ). Number of setae hr on anal valves variable, probably depended on age.

Legs 1–3 with 1, 2, 2 setae on upper subcoxae, 0, 2, 2 setae on lower subcoxae, 3, 6, 7 setae on coxae, 6, 6, 6 on trochanters, and 13, 12, 11(12) setae on femora. Tibiotarsi with most complete set of setae: 19, 19, 18, seta M present. Unguis toothless ( Fig. 53 ).

Remarks. The conspecificity of this Far Eastern form with the true P. porcella comb. nov., the latter species described from central Alaska, raises certain doubts. However, it is impossible to reliably distinguish it from the Alaskan species on the basis of the available description. The existing differences, for example, the number of setae on Th. I, are insignificant and variable. The most characteristic feature of P. porcella comb. nov. (and the above Far Eastern specimens as well) is the anterior position of the sensilla in the dorsolateral groups on Th. II–III. This position of sensilla makes it distinguished from all known species of the genus with a reduced chaetom, but it has been noted for P. obesa , P. pallida sp. nov. and P. caeca sp. nov., which have a more complete set of setae on the thoracic segments.

In addition to the peculiar thoracic chaetotaxy, fairly good diagnostic features of P. cf. porcella are a strongly elongate pair of proximal setae on the labrum (a character unique for the set of species under consideration, but not known for Alaskan individuals), and a labium of the first type (shared only with P. deharvengi , P. pax sp. nov. and P. cedrina sp. nov.).

Figures

FIGURE 1. Map of main sampling plots. 1, Amur Region, Zeya State Nature Reserve; 2, Amur Region, Arkhara; 3, Southern Primorye, «Kedrovaya Pad» State Nature Reserve; 4, Southern Primorye, Ussuri State Nature Reserve; 5, Southern Primorye, Anisimovka, Mount Khualaza; 6, Southern Primorye, Mount Olkhovaya; 7, Southern Primorye, Chuguevka; 8, Southern Pri- morye, Mount Oblachnaya; 9, Southern Primorye, Sikhote-Alin State Nature Reserve; 10, Khabarovsk Territory, Ko Mountains; 11, Khabarovsk Territory, “Arseniev’s granites” Mts. Range; 12, Khabarovsk Territory, Komsomolsk State Nature Reserve; 13, Khabarovsk Territory, Tormasu River; 14, Khabarovsk Territory, Anyuinski National Park.

FIGURES 49–55. Philotella cf. porcella: 49, dorsal chaetotaxy; 50, ocular field and PAO; 51, labrum cone; 52, labium; 53, tip of leg III (lateral view); 54, Ant. III–IV (lateral view); 55, ventral chaetotaxy of abdomen. Scales. Figs 49, 55: 0.1 mm; 50–54: 0.01 mm.