Allopsontus perfectus 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 : 442-445

Allopsontus perfectus Kaplin , sp. nov.

( Figs 5 , 6 )

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 stones, June 07, 2019, G. Shakula leg. Pൺඋൺඍඒඉൾ: 1 ♀ (on slide), the same locality, G. Shakula leg. ( VIZR).

Description. Body length: male 10.5 mm, female 8.8 mm. Body width: male 2.4 mm, female 2.2 mm. Cercus length: male 3.5 mm, female 2.7 mm. Total width of eyes: male 0.83 mm, female 0.80 mm. Eye length: in both sexes 0.44 mm. Paired ocellus width: male 0.30 mm, female 0.23 mm. Ocellus length: male 0.15 mm, female 0.13 mm. Coxal styli length: male 0.75–0.80 mm, female 0.46–0.50 mm. Antennae slightly shorter than body. General body color whitish or light yellowish.Antennal base, frons, gena, occiput, hypopharynx, mandible, maxilla, 1 st –3 rd palpomeres of maxillary palp, labium with violet pigment of weak intensity. Flagellum of male brown. Scales on upper surface of body brown and light brown. Color of scales on lower surface of body light brownish. Distal chains of flagellum divided into 5 annuli in male and 8–9 annuli in female ( Fig. 5A ). Cercus in male approximately 0.33, female 0.31 times as long as body length, including about 16 divisions in both sexes.

Compound eyes dark with bluish tint (in alcohol). Ratio of length to width of compound eye about 1.07–1.11; ratio of contact line length to eye length about 0.39, in both sexes ( Fig. 5B ). Paired ocellus sublateral, ovoid, light brown with narrow white border, in male 2.0 and in female 1.8 times as wide as long. Distance between inner margins of paired ocelli in male about 0.46 and in female 0.40 of total width of compound eyes. Frons between paired ocelli not convex.

Apical palpomere of maxillary palp in male about 0.80 and in female 0.86 times as long as preceding one. Their 5 th palpomere about 1.5 times as long as 4 th palpomere, in both sexes. Dorsal surface of 7 th, 6 th and 5 th palpomeres of maxillary palp respectively with 10–11, 9–11 and 2 hyaline spines in male and 13, 14 and 3–4 spines in female. Ventral surface of 2 nd –7 th palpomeres of male maxillary palp as well as dorsal surface of 1 st palpomere and almost full surface of 2 nd and 3 rd palpomeres of male labial palp with numerous short, adpressed chaetae ( Figs 5C, D ). Apical palpomere of labial palp triangularly oval, in male 2.0 and in female 2.2 times as long as wide; with about 100 sensorial cones in male and 20 in female. Mandibles with four distal teeth in both sexes ( Fig. 5E ).

Fore and middle femur widened, in both sexes ( Table 7). Fore femur of male with opened sensory field, which includes about 40–45 relatively large rosette-shaped sensilla. Sensory field connects to distal row of strong chaetae ( Fig. 5F ). Metric rations concerning sensory field and femur as follows: LSF/WSF: 2.28, LSF/LF: 0.61, WSF/ WF: 0.47, d/LF: 0.25, d/LSF: 0.41, d/WSF: 0.94. Ratio of length of 3 rd tarsomere to total length of hind tarsus about 0.34–0.36 in male and 0.41– 0.43 in female. Undersurface of tarsus and tibia with two rows of pigmented spines ( Table 8). Fore femur of male with about 20 such spines. Middle and hind femora of male and all femora of female with 2–4 spines. Ratio of length of styli to width of middle and hind coxae about 1.6–1.8 in male and 1.2–1.4 in female ( Fig. 5G ).

In both sexes, urocoxites I, VI and VII with 1 + 1 eversible vesicles, urocoxites II–V with 2 + 2 eversible vesicles. Ratios of lengths of urosternites, urostyli (without apical spines) and urocoxites II–IX as shown in Table 9. Posterior angle of urosternites II–VI 103°–110° in male and 110°–114° in female, urosternites VII 106° in male and 150° in female and VIII about 158° in male.Urocoxites VII of female with protruding lobes between eversible vesicles. Ratio of length to width of one lobe about 0.67 ( Fig. 6A ). Thoracic tergites, urotergites I, II, urosternites, urocoxites I, II in both sexes and IX in female without sublateral spines. Urocoxites IX in male with 2 + 2 outer sublateral spines ( Fig. 6B ). Distribution of sublateral spines on urocoxites and urotergites as shown in Table 10.

Male genitalia with parameres on urite IX. Parameres with 1 + 5 divisions surpassing apex of penis. Penis and parameres almost attaining level of apex of urocoxites IX ( Fig. 6B ). Penis typical for the genus Allopsontus . Ratio of width to length of its apical division about 0.48. Distal division of penis about 1.1 times as long as its basal division.

Ovipositor sclerotized in distal part, thickened, almost completely covered by urocoxites IX, stout. Gonapophyses VIII and IX with 26 divisions. Apical spines of anterior and posterior gonapophyses relatively short, as long as 1.5 distal divisions combined. Eleven distal divisions of anterior gonapophysis and 6 distal divisions of posterior gonapophyses with fossorial spines. About three basal divisions of anterior gonapophysis and two basal divisions of posterior gonapophysis glabrous. Distribution of chaetae on divisions of gonapophyses as shown in Figs 6C, D .

Differential diagnosis. Allopsontus perfectus sp. nov. with 2 + 2 eversible vesicles on urocoxites II–V in both sexes and relatively short,sclerotized in distal part and thickened ovipositor with fossorial teeth, belongs to the subgenus Machilanus . Only one species with numerous short chaetae on the ventral surface of the 2 nd –7 th palpomeres of the male maxillary palp has been described in the subgenus Machilanus , A. bitschi ( Wygodzinsky, 1962) from Afghanistan. However, the male labial palp of A. bitschi lacks numerous short chaetae (WඒGඈൽඓංඇඌKඒ 1962). Ratio of length to width of compound eye: A. perfectus sp. nov. 1.1, A. bitschi 1.2; ratio of length of contact line to length of eye about 0.4 and 0.6, respectively. Paired ocellus of A. perfectus sp. nov. ovoid, in A. bitschi more rounded.Ratio of width to length of paired ocellus in A. perfectus sp. nov. 1.8–2.0, in A. bitschi 1.4–1.5. Apical division of penis in A. bitschi thicker. Ratio of width to length of apical division of penis in A. perfectus sp. nov. about 0.48, in A. bitschi 0.60. The new species has several highly specialized adaptations in the structure of the male maxillary and labial palps (numerous short, adpressed chaetae on the ventral surface of the 2 nd –7 th palpomeres of maxillary palps as well as on the dorsal surface of the 1 st palpomere and on almost all the surface of the 2 nd and 3 rd palpomeres of labial palps), legs (large sensory field on fore femora in male, tarsi and tibiae with spines in both sexes) and ovipositor (gonapophyses with fossorial teeth).

Etymology. The species epithet is a Latin adjective perfectus (- a, - um), meaning perfect, referring to the numerous short adpressed chaetae on the male maxillary and labial palps, the apical palpomere of the male labial palp also with numerous sensorial cones, fore femur of male with well developed sensory field, fore and middle femur widened, undersurface of tarsus and tibia with pigmented spines, in both sexes; ovipositor sclerotized, thickened, relatively short, with fossorial spines in the distal part.

Habitat. Petrophytic steppe.

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

Figures

Fig. 5. Allopsontus perfectus sp. nov. male, holotype:A – distal chain of flagellum; B – eyes and ocelli, front view; C – maxillary palp; D – labial palp; E – apex of mandible; F – part of fore leg; G – hind coxa with stylus. Scale bar: 0.1 mm.

Fig. 6. Allopsontus perfectus sp. nov. (B – male, holotype; A, C, D – female, paratype):A – urocoxites VII; B – urocoxite IX, with parameres and penis; C – anterior gonopophysis; D – posterior gonopophysis. Scale bar: 0.1 mm.