Megalothorax bokovae

Description. General aspect. Habitus and segmentation typical of the genus. Body length around 0.3 – 0.4 mm. Specimens whitish in alcohol. Body chaetotaxy sparse including chaetae, s-chaetae, trichobothria, neosminthuroid chaetae, wax-rods and inner sensilla within sensory fields 2 – 6. Chaetae ordinary on body, without any remarkable development (Figs 1 A – B, 2 A). Integument. Secondary granulation made of the usual dorsal rough granules. Integumentary channels extending laterally and dorsally in anterior and posterior parts of head. Anterior canal branching. Channels connection with linea ventralis could be compared to a roundabout. Detailed topology of channels not studied due to limited number of specimens. Sensory fields and wax rods (Figs 1 A – B, 2). Sensory field sf 1 with one wrc-chaeta (wrc) and without inner sensilla (s). Sf 2 with one s and one wrc, sf 3 with three s and one wrc, sf 4 and sf 5 with two s and one wrc, sf 6 with one s and two wrc (Figs 1 A, 2). All s are flame-shaped, but some sensilla are small, and easily confused with a secondary granule and sometimes difficult to distinguish under a light microscope. Body with a total of 14 + 14 wrc (2 + 2 on head, 12 + 12 on trunk), including 8 + 8 free wrc not associated with sensory fields. Wrc 7 notably larger than others with thicker rod similar to a candle inserted into a candlestick (Fig. 2 A). Wrc 7 with a small area without secondary grain around it. Mouthparts. Labrum typical for the genus, with chaetae a 1 and a 2 smooth and not forked. Labium with 4 + 4 proximal chaetae (Fig. 1 C). Basomedian fields with 3 + 3 chaetae. Labial palp (Fig. 1 C), as common for the genus (A, B, C, D, E, b 1, b 2, d 1, d 2, 2 e, H, h 1, h 2). Oral fold and maxillary outer lobe (Fig. 1 D) as typical for the genus, with one sublobal hair. Maxillary head ordinary. Head chaetotaxy. Forehead chaetotaxy as on Fig. 1 A – B. Clypeal-labral formula: 2, 5, 5, 4 / 5, 5, 4 (Fig. 1 A). Chaeta a 0 absent but an unpaired chaeta in cl. m row. Head with oval small papilla mimicking a “ nose ” (Figs 1 A – B). Dorsal posterior area with 14 lanceolate chaetae (Fig. 1 A). Ventral side with three pairs of postlabial chaetae. Trend for posterior chaetae to be longer and stronger than anterior chaetae. Antennal chaetotaxy (Figs 3 A – B). Ant. I and II with one and four chaetae, respectively. Ant. III with eightnine chaetae and two long S-chaetae (S 1 and S 4). Striations of Ant III sensory organ short sensilla (S 2 and S 3) distinguishable in light microscopy. Ant. IV with six chaetae (including X-chaeta) and nine-ten S-chaetae (trait variable). Some specimens have shortened S-chaetae (corresponding to Sb 1, 3, 4 and Sa 5) sometimes are barely distinguishable from chaetae. But other samples have ordinary S-chaetae. Sensory organ with Sx, Sy, Or, a, Sa; Or short, seems apically flared. Diagram of the chaetotaxy of the antenna in Fig. 3 C. Summary on antennal chaetotaxy provided in Table 1. Body chaetotaxy. Th. II with 12 + 12 chaetae, 1 + 1 tubular and curved s 1 - sensilla (Fig. 2 A). Th. III with 10 + 10 chaetae, 6 + 6 free wax-rods (wrc 1 – 6). Chaetae p 4 not close to wrc 2 (Fig. 2 A). Chaeta a 5 and a 6 subequal. Abd I – V terga with 19 + 19 ordinary chaetae, with 1 + 1 greatly enlarged free wax-rods resembling a candle inserted into a candlestick, 1 + 1 globular sensillum s 2. Globular sensillum s 3 absent. Chaetae of body subequal, slightly thickened. Trichobothria could not be studied for this species. Legs chaetotaxy typical of the genus (Table 2), consisting of ordinary chaetae of variable size (Fig. 4 A – C). Claws. Claw III bulkier than claw I and II. Claws subequal in unguis length (with a trend as unguis I> unguis II> unguis III). Unguis basal and posterior auxiliary lamellae (la, lp and Bp) well developed (Fig. 4 A – C). Unguiculus 0.5 – 0.6 as long as unguis. Abd. IV sternum and furca. Abd. IV sternum with 2 + 2 neosminthuroid chaetae and 2 + 2 chaetae. Manubrium with 2 + 2 posterior chaetae (Fig. 4 D) and 1 + 1 pegs with convex tip articulated with a corresponding concavity of the dens. Proximal subsegment of dens with a posterior chaeta (Fig. 4 D); distal subsegment posteriorly with two basal spines and one chaeta at the middle. Anterior side of dens with five apical spines, spines without elongated apex. Mucro narrowing in the distal ⅖, posterior lamellae smooth, with one notch. Chaetotaxy of Abd. V and VI not studied, apparently ordinary for the genus. Genital plate. Female apparently ordinary for the genus, male unknown. Tenaculum and ventral tube. Tenaculum with 3 + 3 hook-like teeth (Fig. 4 E). Ventral tube bulky with two apical pairs of chaetae. Name derivation. Megalothorax bokovae sp. nov. is dedicated to Anna Bokova, who helped to preserve the holotype of this species and thanks to whom the description of this species became possible at all.

Figs 1 – 4, Table 1 – 2

Type material. Holotype: female on slide, Russia (European part), Nenets Autonomous Okrug, Yugorsky Peninsula, Mys Belyy Nos [69.50 ° N, 60.21 ° E], dryadnik (Dryas meadow) with legumes on the southern slope; 08.07. 2015; leg. A. Babenko. 2 paratypes, female on slide, in the same location. 10 paratypes, female on slide, Kazakhstan, Alma-Ata, Shortcut to the « Three Brothers » Peak [43.13 ° N, 77.01 ° E], coniferous forest on the southern slope; 20.06.2024; leg. A. Shamrina. The holotype and 11 paratypes deposited in the collection of the Department of Zoology & Ecology, MSPU. One paratype was deposited in SMNG. Obtained molecular data. Kazakhstan, one individual sequenced for COI and 28 S rDNA D 1 – D 2, another individual sequenced for 28 S rDNA D 1 – D 2 [PQ 662848, PQ 672534, PQ 672535], same collection data as above.