Philotella pax, 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 : 529-531

Philotella pax sp. nov.

Figs 2–9

Type material. Holotype: juvenile, Southern Primorye , Ussuri State Nature Reserve ( Fig. 1 , point 4), forest with Pinus koraiensis , 43°38.88’N 132°21.09’E, ~ 200 m alt., rotten wood, 22 July 2016. N. Kuznetsova & M. Potapov leg. Paratypes: 3 juveniles, same data, but ~ 380 m alt., forest with P. koraiensis , litter, 22 July 2016 .; 3 juveniles, same region and Nature Reserve, mixed forest, 43°38.2’N 132°20.93’E, ~ 380 m alt., litter, 23 July 2016. N. Kuznetsova & M. Potapov leg.

Additional material. 2 juveniles, same region, «Kedrovaya Pad» State Nature Reserve ( Fig. 1 , point 3), mixed coniferous-broadleaf forest, 43°6.88’N 131°29.23’E, ~ 200 m alt., litter, 27 July 2016. N. Kuznetsova & M. Potapov leg. ; 2 juveniles, same region, ~ 30 km SE of Chuguevka ( Fig. 1 , point 7), mixed forest, 44°1.32’N 134°9.02’E, 500 m alt., 11 August 2017. N. Kuznetsova, A. Kuprin & A. Geraskina leg. ; 6 juveniles, same region and collectors, Ussuri State Nature Reserve ( Fig. 1 , point 4), valley of Anikin River, broadleaf forest, litter, 43°40.102’N 132°29.91’E, 13 August 2017 .

Diagnosis. A dark species characterized by the presence of 5+5 subequal ocelli; the second row of labral setae with three longer and two shorter setae; a labium of the first type; dorsal chaetotaxy with setae p2 present on Th. II–III but absent on Abd. I–V; the dorsolateral group of setae on Th. II–III with sensillum p3 set below two ordinary setae (a3 and m4); a complete tibiotarsal chaetotaxy and toothless unguis.

Description. Length (without antennae) of available juveniles 0.33–0.42 mm, holotype — 0.40 mm. Habitus typical of the genus. Colour blue, uniformly dark. Tegument granulation very strong, especially on abdominal tip.

Antennae clearly shorter than head, Ant. III–IV fused dorsally. Ant. IV with simple or 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. 4 ); few sensilliform setae of various shape also present on its ventral side. Antennal organ of Ant. III typical, inner sensilla small, sgv slightly longer than sgd and curved, ventral ms present. Ant. I–II with 7 and 11–12 setae, respectively.

Head with 5+5 ocelli, slightly larger than surrounding secondary granules on ocular field ( Fig. 5 ). PAO usually rounded, consisting of 8–10 vesicles, its axis to ocellus B ratio as 2.1–2.3: 1. Buccal cone short and blunt. Maxilla styliform, with at least one lamella bearing two small apical teeth ( Fig. 6 ). Mandible delicate, with two tiny denticles on inner edge between apical and two basal teeth ( Fig. 7 ). Labrum usually with a common set of 4/2352 setae of different length, distal pair and three setae of the next row being the longest ( Fig. 8 ). Main part of labium of the first type with three ordinary setae in line along distal edge and 2+2 axial setae between fairly large sensorial elements ( Fig. 9 ); submentum and mentum with usual set of four setae each. Head ventrally with 2+2 postlabial setae as usual.

Dorsal chaetotaxy symmetrical and rather reduced ( Fig. 2 ). Ordinary setae short, needle-like, sensilla clearly longer than ordinary setae, their number as usual: 22/11111, lateral ms present on Th. II. Main characteristics: head usually with unpaired seta d0 and only 2 setae on each ocular field; Th. I with 3+3 setae; Th. II–III with 3+3 axial setae (p2 present), dorso-lateral group consisting of two setae (a3 and m4) additionally to sensilla p 3 in backward position. Abd. I–III without p2, i.e. only 2+2 axial setae present, and with only one seta (a3) between axial group and sensillum p 4; 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 ( Fig. 3 ). Furcal remnant in a form of two swellings, each with a seta, at anterior border of Abd. IV. Anal valves with two [?] hr-setae each.

Legs I–III with 1, 2, 2 setae on upper subcoxae, 0, 2, 2 setae on lower subcoxae, 3, 6, 6 setae on coxae, 6, 6, 6 on trochanters, and 13, 12, 10–11 setae on femora. Tibiotarsi with most complete set of setae: 19, 19, 18, seta M present. Unguis toothless.

Remarks. Unfortunately, only juveniles without any traces of a genital opening are present in the available material. However, based on a comparison of juvenile and adult individuals of other congeners, morphological rearrangements related to age can be assumed as not being too significant in the genus, failing to affect the main diagnostic characters, as a rule. The only notable exception is the ventral chaetotaxy of the abdomen, which is clearly more abundant in adults.

Etymology. The species is named after the ancient goddess of peace in honour of those who uphold it. The name is a noun in apposition.

Affinities. In general, P. pax sp. nov. seems to be especially similar to North Korean P. miracli . Their dorsal chaetotaxy is almost identical, except for the presence of two (a3 and m4) rather than three (a3, a4 and m4) setae in the dorsolateral group on Th. II–III. That this may be due to the juvenile condition of the type material cannot be ruled out, although such an assumption seems doubtful to us. The most significant difference between these two species lies in the structure of the labium: P. pax sp. nov. is characterized by a labium of the first type (see above), while the true P. miracli possesses a labial palp of the second type, with a triangular arrangement of setae A, C and D. A toothless unguis and a complete set of tibiotarsal setae also allows for P. pax sp. nov. to be distinguished from all three North Korean species described by Najt & Weiner (1985), which lack setae M on the tibiotarsi.

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 2–9. Philotella pax sp. nov.: 2, dorsal chaetotaxy; 3, ventral chaetotaxy of abdomen; 4, Ant. III–IV (lateral view); 5, ocular field and PAO; 6, maxillary head; 7, left and right mandibles; 8; labrum; 9, labium. Scales. Figs 2–3: 0.1 mm; 4–9: 0.01 mm.