Allopsontus nigrostriatus Kaplin, 2021

Kaplin, Vladimir & Shakula, Georgiy, 2021, New species of bristletails of the family Machilidae (Archaeognatha) from Kazakhstan, Acta Entomologica Musei Nationalis Pragae 61 (2), pp. 435-445 : 439-442

Allopsontus nigrostriatus Kaplin , sp. nov.

( Figs 3 , 4 )

Type material. Hඈඅඈඍඒඉൾ: ♂ (slide-mounted, VIZR): KAZAKHSTAN: Almaty Region, Raiymbek District, 43°02′2.5′′N, 78°48′51.4′′E, upper Charyn River, ≈ 1817 m, petrophytic steppe, under stone, June 07, 2019, G. Shakula leg.

Description. Body length: 7.3 mm. Body width: 2.0 mm. Cercus length: 3.1 mm. Total width of eyes: 0.84 mm. Eye length: 0.50 mm. Paired ocellus width and length: 0.24 mm and 0.11 mm, respectively. Coxal stylus length: 0.50–0.55 mm. Antennae slightly longer than body. General body color whitish.Antennal base, frons, gena, occiput, hypopharynx, mandible, maxilla, postabdomen with violet pigment of weak intensity. Upper surface of body with scale pattern composed of two almost black and three light brownish-gray longitudinal stripes of approximately equal width. Lower surface of body covered with light brownish- -gray and white scales. Distal chains of flagellum divided into 9–11 annuli. Cercus approximately 0.43 body length.

Compound eyes dark with bluish tint (in alcohol). Ratio of length to width of compound eye about 1.19; ratio of contact line length to eye length about 0.50 ( Fig. 3A ). Paired ocellus sublateral, ovoid, light brown with narrow white border, 1.9 times as wide as long. Distance between inner margins of paired ocelli about 0.54 and between their outer margins 0.93 total width of compound eyes. Frons between paired ocelli not convex.

Apical palpomere of maxillary palp about 1.03 times as long as preceding one. 5 th palpomere about 1.4 times as long as 4 th palpomere. Dorsal surface of 7 th, 6 th and 5 th palpomeres of maxillary palp with 14, 13 and 3 hyaline spines, respectively ( Fig. 3B ). Ventral surface of 5–7 th palpomeres of maxillary palp with numerous short, adpressed and pigmented chaetae, absent on labial palp. Apical palpomere of labial palp triangularly oval, 2.1 times as long as wide; with about 35 sensorial cones ( Fig. 3C ). Mandibles with four distal teeth ( Fig. 3D ).

Fore and middle tibiae and femora widened ( Table 3). Fore femur with opened sensory field, which includes about 65–70 relatively large rosette-shaped sensilla. Sensory field is in contact with distal row of strong chaetae ( Fig. 3E ). Metric rations concerning sensory field and femur as follows: LSF/WSF: 1.88, LSF/LF: 0.52, WSF/ WF: 0.38, d/LF: 0.32, d/LSF: 0.61, d/WSF: 1.15. Ratio of length of 3 rd tarsomere to total length of hind tarsus about 0.41–0.42. Undersurface of tarsus and tibia with two rows of pigmented spines, absent on middle and hind femur ( Fig. 3F , Table 4). Fore femur with 35–40 such spines. Ratio of length of styli to width of middle and hind coxae about 1.2 and 1.4, respectively.

Urocoxites I–VII with 1 + 1 eversible vesicles ( Fig. 4A ). Thoracic tergites, urotergites I–III and X, urosternites and urocoxites without sublateral hyaline spines ( Fig. 4B ). Number of sublateral hyaline spines on urotergites IV–VIII 2 + 2, IX 3 + 3. Ratios of lengths of urostyli (without apical spine), urosternites and urocoxites II–IX as shown in Table 5. Posterior angle of urosternites II–VI 96°–103°, VII about 130°.

Male genitalia with parameres on urite IX. Parameres with 1 + 5 divisions slightly not surpassing apex of penis, almost attaining level of apex of urocoxites IX ( Fig. 4C ). Penis thick, ratio of width to length of its apical division about 0.67. Lengths of basal and apical divisions of penis almost the same.

Differential diagnosis. Allopsontus nigrostriatus sp. nov. with 1 + 1 eversible vesicles on urites II–VII belongs to the subgenus Kaplinilis , to the group of species with numerous short, adpressed and pigmented chaetae on the ventral surface of the 5–7 th palpomeres of male maxillary palp and absent on their labial palp. This group includes two described species: A. volgensis Kaplin, 1999 from Samara Region and A. smelyanskii Kaplin, 1999 from Orenburg Region (both Russia). Allopsontus nigrostriatus sp. nov. differs from A. volgensis and A. smelyanskii in the length of the body and antenna, color of scales on the upper surface of the body, number of annuli in the distal chains of flagellum, shape of compound eye and paired ocellus, structure of the apical palpomere of the labial palp, number of divisions in parameres. The significant differences between these species are summarized in Table 6.

Etymology. Name of the species is a compound Latin adjective nigrostriatus (- a, - um), meaning ʻhaving black stripesʼ, referring to the color of scales on the upper surface of the body.

Habitat. Petrophytic steppe.

Distribution. Kazakhstan (Almaty Region, Raiymbek District, upper Charyn River).

Figures

Fig. 3. Allopsontus nigrostriatus sp. nov. male, holotype: A – eyes and ocelli, front view; B – maxillary palp; C – labial palp; D – apex of mandible; E – part of fore leg; F – part of middle leg. Scale bar: 0.1 mm.

Fig. 4. Allopsontus nigrostriatus sp. nov.male, holotype:A – urocoxites and