Philotella pallida, 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 : 541

Philotella pallida sp. nov.

Figs 38–43

Type material. Holotype: female, Khabarovsk Territory, Lazo District, mountain range «Arseniev’s granites», valley of Malyi Katen River ( Fig. 1 , point 11), 500–600 m alt., mixed forest, litter, 08 July 2019. A. Brinev leg. Paratypes: 4 females and 1 male, same data as holotype .

Diagnosis. A species of the genus Philotella characterized by a pale colouration; the presence of 3+3 slightly coloured ocelli; the labral setae almost equal in length; a labium of the second type, dorsal chaetotaxy with p2 setae present on all terga from Th. II to Abd. III; four ordinary setae (a3, a4, m4 and p4) in dorsolateral group on Th. II–III additionally to sensillum p3 set slightly above seta p4 and usually two setae (a3 and p3) between axial group and sensillum p4 on Abd. I–III; a complete tibiotarsal chaetotaxy, and toothless unguis.

Description. Length (without antennae) of available specimens 0.44–0.63 mm, holotype — 0.52 mm. Habitus typical of the genus. Colour light blue, pigment granules sparsely distributed all over dorsal side of body. Tegument granulation moderate, not especially coarse.

Antennae clearly shorter than head, Ant. III–IV fused dorsally. 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 clearly differentiated, blunt and elongate ( Fig. 39 ); 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 12 setae, respectively.

Head with 3+3 ocelli, slightly larger than surrounding secondary granules on ocular field. PAO rounded, consisting of 7–9 vesicles, its axis to ocellus B ratio as 1.7–2.2: 1. Buccal cone not especially short. Maxilla styliform, with two small denticles on apex and at least two lamella bearing two apical teeth ( Fig. 40 ). Mandible delicate, with usual five teeth ( Fig. 41 ). Labrum with a common set of 4/2352 setae of similar length, distal pair and two marginal setae of the next row being slightly longer. Main part of labium of the second type with three ordinary setae in triangular position and 1+1 axial setae between sensorial elements ( Fig. 42 ); submentum and mentum with usual set of four setae each. Head ventrally with 2+2 postlabial setae as usual.

Dorsal chaetotaxy rather complete, often with some abnormalities ( Fig. 38 ). Ordinary setae short, needle-like, sensilla longer, their number as usual: 22/11111, lateral ms present on Th. II. Main characteristics: Th. II–Abd. III with 3+3 axial setae (p2 present), dorso-lateral group on Th. II–III usually consisting of four setae (a3, a4, m4 and p4) additionally to sensilla p3, sometimes one of them absent. Abd. I–III with or without p3, i.e. 2+2 or 3+3 p-setae present between sensilla. Abd. V with 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. 43 ). Furcal remnant in a form of two swellings, each with a seta, on anterior border of Abd. IV. Unpaired anal valve usually with three setae hr, number of these setae on paired vales variable.

Legs 1–3 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, 11 setae on femora. Tibiotarsi with most complete set of setae: 19, 19, 18, seta M present. Unguis toothless.

Etymology. The name of the new species reflects its light coloration, from the Latin pallidus.

Affinities. Philotella pallida sp. nov. is characterized by a quite complete dorsal chaetotaxy, which is comparable only with that of P. caeca sp. nov. (see below). The latter species also has setae p2 on all terga from Th. II to Abd. III, and a complete set of setae (a3, a4, m4, S = p3 and p4) in dorsolateral position on Th. II–III. These two species can easily be distinguished by colouration (light bluish-grey in P. pallida sp. nov., vs colourless in P. caeca sp. nov.), granulation (moderate in P. pallida sp. nov., vs coarse in P. caeca sp. nov.), presence/absence of ocelli, and the number of lobes and shape of the PAO (rounded with 7–9 lobes in P. pallida sp. nov., vs elliptic with 12–15 lobes in P. caeca 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 38–43. Philotella pallida sp. nov.: 38, dorsal chaetotaxy; 39, Ant. III–IV (lateral view); 40, maxillary head; 41, mandible; 42, labium; 43, ventral chaetotaxy of abdomen. Scales. Figs 38, 43: 0.1 mm; 39–42: 0.01 mm.