Philotella amurica, 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 : 537

Philotella amurica sp. nov.

Figs 25–30

Type material. Holotype: immature male, Khabarovsk Territory, Komsomolsk State Nature Reserve ( Fig. 1 , point 12), Gorin River , 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. Paratypes: 2 females, same data as for holotype .

Diagnosis. A species of the genus Philotella characterized by the presence of 2–3 ocelli on each side of the head; a labrum with subequal setae in the second row; a labium of the second type; dorsal chaetotaxy with p2 present on Th. II –III but absent on Abd. I –V; three ordinary setae (a3, a4 and m4) in dorsolateral group on Th. II –III and two setae (a3 and p3) between axial group and sensilla on Abd. II –III; a slightly reduced tibiotarsal chaetotaxy without M-seta and a toothless unguis.

Description. Length (without antennae) up to 0.49 mm, holotype — 0.43 mm. Habitus typical of the genus. Alive colour unknown, probably rather dark. Tegument granulation not especially coarse.

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 clearly differentiated, blunt and elongate; 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 setae, respectively.

Each side of head with 2–3 ocelli of different size, individual variations frequent. PAO rounded, consisting of 7–9 vesicles, its axis to ocellus B ratio as 2.3–2.4: 1 ( Fig. 28 ). Buccal cone short and blunt. Maxilla styliform, lamellae not clearly seen. Mandible delicate, with five teeth, two of which tiny and hardly detected. Labrum with a common set of 4/2352 setae, slightly different in length ( Fig. 26 ). Main part of labium of the second type with three ordinary setae set in a triangular arrangement and 1+1 axial setae between sensorial elements ( Fig. 27 ); submentum and mentum with usual set of four setae each. Head ventrally with 2+2 postlabial setae.

Dorsal chaetotaxy almost symmetrical ( Fig. 25 ). Ordinary setae short, needle-like, sensilla clearly differentiated, their number as usual: 22/11111, lateral sensilla on Th. II and dorsal ones on Abd. IV clearly thickened. Th. II with lateral ms present. Main characteristics: head usually with unpaired seta d0, ocular field with 3 setae; Th. I with 3+3 setae; Th. II–III with 3+3 axial setae (p2 present); dorsolateral group consisting of 3 ordinary setae (a3, a4 and m4) additionally to sensillum p 3 in backward position; Abd. I–III with 2+2 axial setae (p2 absent). Abd. I with only one seta between axial group and sensilla, whereas Abd. II–III always have two setae (a3 and p3) on this position. Abd. IV usually with 3+3 setae between sensilla, Abd. V with 2+2 such setae.

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. 30 ). Furcal remnant in a form of two swellings, each with a seta, on anterior border of Abd. IV. Number of hr-setae on anal valves unstable in studied specimens.

Legs 1–3 with 1, 2, 2 setae on upper subcoxae, 0, 2, 2 setae on lower subcoxae, 3, 6, 6 setae on coxae, 5, 5, 5(6) on trochanters, and 12, 11, 10 setae on femora. Tibiotarsi with 18, 18, 17 setae, i.e. seta M absent ( Fig. 29 ). Unguis toothless.

Etymology. The new species is named after the region of its type locality, the lower reaches of the Amur.

Affinities. Philotella amurica sp. nov. is the only known species in the genus in the study area that lacks a Mseta on the tibiotarsi, a character which is typical of all North Korean congeners: P. deharvengi , P. miracli and P. tertia . Among the latter trio, P. amurica sp. nov. resembles P. miracli particularly strongly in having a similar dorsal chaetotaxy and the labium of the same type, but it clearly differs in the number of ocelli (2–3, vs 5 in P. miracli ). In addition, there are also some other consistent differences between these species: the presence of 2+2 setae between the axial group and sensilla on Abd. II–III (vs only 1+1 setae in this position in P. miracli ) and 3+3 setae between sensilla on Abd. IV (vs only 2+2 axial setae in P. miracli ).

The dorsal chaetotaxy of P. amurica sp. nov. is even more similar to that of P. aliniensis sp. nov. (cf. Fig 25 & Fig. 24 ). These species are also characterized by the same type of the labium, and a reduced number of ocelli, but it can easily be distinguished due to the significant differences in granulation and the presence/absence of a M-seta 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 25–30. Philotella amurica sp. nov.: 25, dorsal chaetotaxy; 26; labrum; 27, labium; 28, ocular field and PAO; 29, tip of leg III (inner side); 30, ventral chaetotaxy of abdomen. Scales. Figs 25, 30: 0.1 mm; 26–29: 0.01 mm.

FIGURES 17–24. Philotella cedrina sp. nov. (17–21) & Philotella aliniensis sp. nov. (22–24): 17; labrum; 18, labium; 19, dorsal chaetotaxy; 20, Abd. V–VI (ventral); 21, lateral sensilla on Th. II–III, sensilla of Abd. III–V (top down); 22, labium; 23, ocular field and PAO; 24, dorsal chaetotaxy. Scales. Figs 19, 24: 0.1 mm; 17–18, 20–23: 0.01 mm.