Charimachilis rostoviensis Kaplin, 2020

Kaplin, Vladimir & Martynov, Vladimir, 2020, Three new species of bristletails of the families Meinertellidae and Machilidae (Archaeognatha) from Ukraine and Southern Russia, Acta Entomologica Musei Nationalis Pragae 60 (2), pp. 463-474 : 470-473

Charimachilis rostoviensis Kaplin , sp. nov.

( Figs 6 , 7 )

Type material. HƟΓƟΤΥΡΕ: ♀ (slide-mounted, ZIN), RUSSIA: Rostov-on-Don, Botanical garden of the Southern Federal University, 47°14′13″N, 39°39′12″E, 50 m a.s.l., under a dead pine trunk, June 19, 2019, V. Martynov leg. PΑ*©ΑΤΥΡΕඌ: ♀♀ 3 (one on slide), 6 juv., the same locality, V. Martynov leg. ( ZIN).

Description. Female. Body length 9.6–11.0 mm; body width 2.8–3.1 mm; antennal length 5.8–6.8 mm; cercal length 4.1–4.4 mm; total eyes width 1.00– 1.03 mm, eye length 0.42–0.44 mm; paired ocelli width 0.50–0.51 mm, length 0.18–0.19 mm. Coxal styli length 0.62–0.65 mm. Ovipositor length 1.4–1.6 mm.

General body color whitish, with brown hypodermal pigment of faint or medium intensity only on antennal base, frons, gena, lateral sides of clypeus, mandible, galea of maxilla. Frons between eyes convex. Color of scales on upper and lower surface of body brown. Antennae shorter than body. Distal chains of flagellum divided into 8–12 annuli. Cercus 0.42–0.46 times as long as body length, with about 21 divisions. Apex of cercus with one large lateral spike ( Fig. 6A ). Divisions of cerci, except for apical three, with 1–3 colorless supporting macrochaetae on inner side.

Compound eye color from dark brown to almost black with light gray tint in central part and near eye contact line. Ratio of length to width of compound eye about 0.86; ratio of contact line length to eye length 0.33–0.35. Paired ocelli shoe-shaped, black with narrow white rim, located in front of eyes. Distance between inner margins of ocelli 0.08–0.10 and between their outer margins 0.96–0.98 total width of compound eyes ( Fig. 6B ).

Apical article of maxillary palpus 1.12–1.14 times as long as preceding one. Dorsal surface of 7 th, 6 th, and 5 th articles of maxillary palpus with 17, 13 or 14, and 8 or 9 hyaline spines, respectively ( Figs 6C, D ). Apical article of labial palpus triangularly oval, 2.3 or 2.4 times as long as wide ( Fig. 6E ). Mandibles with four distal teeth ( Fig. 6F ).

Fore and middle femur and tibia widened ( Fig. 6G ). Ratios of lengths to widths of femur, tibia and tarsus as shown in Table 10. Ratio of length of 3 rd tarsomere to total length of tarsus 0.30–0.31. Ventral surface of femora, tibiae and tarsi with spine-like chaetae as shown in Table 11. Middle and hind legs with coxal styli. Ratio of styli length to width of middle and hind coxae about 1.7.

Abdominal segments I–VII with 1 + 1 eversible vesicles ( Figs 7A, B ). Posterior angle of urosternites II–IV, V, VI, and VII approximately 84–86°, 79°, 67°, and 77°, respectively. Ratios of lengths of urosternite, urocoxite and urostylus (without apical spine) II–IX as shown in Table 12.

Inner posterior lobes of urocoxites VII protruding ( Fig. 7B ); ratio of length to width of one lobe about 0.54. Thoracic tergites, urotergites I–IV, urosternites, urocoxites I–VI without macrochaetae. Distribution of sublateral macrochaetae on other urocoxites and urotergites as shown in Table 12. Urocoxites IX with 1 + 1 outer and 6 + 6 inner sublateral spines. Urotergite X with small thin chaetae ( Fig. 7C ).

Ovipositor weakly sclerotized, thickened, completely concealed by urocoxites IX, typical of genus Charimachilis . Anterior and posterior gonapophyses with 17 and 15 divisions, respectively ( Figs 7D, E ). Ultimate division of anterior gonapophyses with preapical spine and 2 apical lateral projections, one of which is pointed and sclerotized. Apical spines as long as 2 or 3 apical divisions combined. Anterior gonapophyses with 4 or 5 lateral digging spikes. Posterior gonapophyses with well developed, sclerotized curved apical horn and preapical spine, as long as 2 apical divisions combined. Distribution of sensory and simple chaetae on divisions of anterior and posterior gonapophyses as in Figs 7D, E .

Male. Unknown. The species is probably parthenogenetic, similar to most its congeners.

Differential diagnosis. Genus Charimachilis Wygodzinsky, 1939 includes 13 described species (KΑΡΓΙΝ 2019). Only females are known in 11 species. This makes it difficult to identify them. Charimachilis rostoviensis sp. nov. most closely resembles C. ukrainensis Stach, 1958 in ovipositor morphology. The main morphological differences between them are shown in Table 13. The posterior angle of urosternites is clearly acute (less than 75°) in C. rostoviensis sp. nov. and almost right (79–86°) in C. ukrainensis from Ukraine. Ratio of cercus length to body length is about 0.3 in C. ukrainensis and more than 0.4 in C. rostoviensis sp. nov. Ratio of stylus length (apical spines excluded) to urocoxite II–VII is 0.6–0.7 in C. ukrainensis and about 0.5 in C. rostoviensis sp. nov. C. rostoviensis sp. nov. is also similar to C. wahrmani Wygodzinsky, 1939 from Turkey in the structure to compound eye, maxillary palpus, urocoxite IX (WΥǤƟĐƶΙΝඌΚΥ 1959). C. wahrmani differs from the new species in ratio of distance between the inner margins of ocelli to the total width of compound eyes, ratio of stylus length to urocoxite VIII, number of sublateral spines on urocoxite IX, and the structure of the anterior and posterior gonapophyses ( Table 13).

Etymology. The species is named after Rostov-on-Don where it was collected; adjective.

Habitats. Old artificial stands of pine Pinus sylvestris L. with undergrowth of Acer tataricum L. in the valley of the Temnik River. Under a trunk of a fallen dead pine.

Figures

Fig. 6. Charimachilis rostoviensis sp. nov., female, holotype: A – distal part of cercus; B – eyes and ocelli, front view; C – 1st–3rd articles of maxillary palpus; D – 4th–7th articles of maxillary palpus; E – labial palpus, with labium (part); F – distal part of mandible; G – part of fore leg. Scale bar: 0.1 mm.

Fig. 7. Charimachilis rostoviensis sp. nov., female, holotype: A – urosternite and urocoxites V (part); B – urosternite and urocoxites VII (part); C – urotergite X (part); D – anterior gonapophysis; E – posterior gonapophysis. Scale bar: 0.1 mm.