Petrobius montanus Kaplin, 2021

Kaplin, V. G., 2021, A new species of the bristletail genus Petrobius Leach, 1809 (Microcoryphia: Machilidae) from Crimea, Far Eastern Entomologist 426, pp. 22-28 : 24-27

Petrobius montanus Kaplin , sp. n.

http://zoobank.org/NomenclaturalActs/ 2CD27A81-E0A2-4780-A5C9-8F9793BE2CE6

Figs 1–11

MATERIAL. Holotype – ♂, Russia: Crimea , Grand Canyon of Crimea, 44°31′40″N,

34°01′00″E, 500–600 m, 07.IX 2020, leg. V. Kaplin, ( VIZR) (in slides). Paratypes – 7 ♂ , 2

♀, same locality, data and collector as for holotype ( VIZR) (2 ♀ in slides; 7 ♂ in 75%

alcohol).

DESCRIPTION. Body length: male and female 8–11 mm. Body width: male and female

2.0– 2.5 mm. Antennae length: about 10–15 mm. Cerci length: 2.9–3.5 mm. Total eyes width:

0.8–0.9 mm. Eye length: 0.46–0.53 mm. Paired ocellus width: 0.43–0.46 mm. Paired ocellus length: about 0.16 mm. Coxal styli length: about 0.5 mm in male and female. Ovipositor length: 3.2 mm.

General body color (in ethanol) whitish, or light yellow, without pigment. Antennal base,

scapus, pedicellus, frons, occiput, mandibles, maxillae, hypopharynx, tarsi, tibiae, femora, 2–

5th palpomeres of maxillary palps, 2nd and 3rd palpomeres of labial palps with brown-violet pigment of low or medium intensity. Tibia and first tarsomere are the most pigmented.

Flagellum of antennae without scales. Scales color light brown, brown or dark brown on the upper surface of the body; light brown on the ventral side of the body. Antennae longer than body. Distal chains of flagellum divided into 12–16 annuli in male and 17–19 annuli in female. Аpical annuli of distal chains with two “rosetenfӧrmige” sensilla of A form (NotarioMuñoz et al. 1997). Cercus approximately 0.36–0.39 (male) or about 0.35 (female) body length, including about 16–17 articles. Apex of cerci with two well developed lateral spikes.

Articles of cerci, except for apical two, with 1–4 colorless supporting macrochaetae on inner side.

Compound eyes dark with blue tint (in alcohol). Ratio of length to width of compound eye 1.14–1.19; ratio of length of contact line to length of eye 0.59–0.70 in both sexes. Paired ocelli whitish or light brown, shoe-shaped, subinferior to compound eyes. Frons slightly swollen between the paired ocelli. Distance between inner margins of ocelli about 0.08 and between their outer margins 0.92–0.95 total width of compound eyes in both sexes ( Fig. 1 ).

Apical palpomere of maxillary palp 0.74 (male) or 0.62 (female) times as long as prece-

ding one, ratio of lengths of 5th and 4th palpomeres 1.33 and 1.23, respectively. Dorsal surface of 7th, 6th and 5th palpomeres of maxillary palp with 12, 11 and 3 (male) or 13, 15

and 2 (female) hyaline spines, respectively ( Fig. 2 ). Apical palpomere of labial palp trian-

gularly oval, 2.8 (male) or 2.7 (female) times as long as wide, with about 22 and 14 sensorial cones, respectively ( Figs 3, 4 ). Mandibles with one (female) or two (male) distal teeth (Figs

5, 6).

Fore and middle femur of male and female widened ( Fig. 7 ). Hind tarsus longer than fore and middle tarsus 1.2 times. Ratios of length to width of femur, tibia and tarsus as shown in

Table 1. Ratio of length of 3rd tarsomere of hind tarsus to its total length 0.31–0.33 in both sexes. Ventral surface of femora, tibiae and tarsi with hyaline spine-like chaetae in both sexes

( Table 2). Ratio of length of coxal styli to width of middle and hind coxae about 1.32–1.34 in male, 1.48–1.55 in female.

♀ (4, 6, 9, 10). 1 – compound eyes and paired ocelli; 2 – maxillary palpus; 3, 4 – labial palpus;

5, 6 – apex of mandible; 7 – fore leg; 8 – posterior portion of urocoxites VIII, with stylus;

9 – urocoxite IX, with anterior gonapophyses; 10 – distal part of anterior gonapophyse; 11 –

urocoxite IX, with penis and paramera. Scale bars = 0.1 mm.

In both sexes, urocoxites I and VI–VII with 1 + 1 eversible vesicles, but urocoxites II–V with 2 + 2 eversible vesicles. Posterior angle of urosternites II–VII approximately 110–112°,

VIII about 130°. Ratios of lengths of urosternites and urocoxites II–VII, on the one hand, and urostyli (without apical spine) and urocoxites II–VII, on the other hand, 0.52–0.63 and 0.56–

0.65, respectively, in both sexes. Ratios of lengths of urostyli and urocoxites VIII 0.73 in male and 0.75 in female, IX 0.77 and 0.64, respectively. Ratios of lengths of apical spines and urostyli II–VIII 0.36–0.40, in both sexes. Thoracic tergites, urosternites, urocoxites I,

IV–IX; urotergites I–IV and X without macrochaetae. Urocoxites II–III with 1 + 1, urotergites

V–VIII with 1+1, IX with 2 + 2 sublateral macrochaetae. Urocoxites VIII in male with slightly protruding lobes between styli ( Fig. 8 ).

Ovipositor slender, elongate, visibly surpassing apex of styli IX ( Fig. 9 ). Anterior and posterior gonapophyses with approximately 61 and 62 divisions, respectively. About forty basal divisions of posterior gonapophyses glabrous. All divisions of anterior gonapophyses with chaetae. Apical spines of gonapophyses as long as about 4.5 apical divisions combined.

Distal divisions of anterior and posterior gonapophyses with 9 and 6 chaetae, respectively

(not counting sensory setae and apical spines) ( Fig. 10 ).

Male genitalia with one pair entire paramera with numerous short bristles on abdominal segment IX ( Fig. 11 ). Parameres noticeable shorter than the basal portion of penis. Ratio length to width of distal portion of penis about 2.8. Penis relatively long, significantly exceed level of the apex of urocoxites IX. Terminal portion of penis covered with bristles, longest in the apical part. Ratio lengths of basal and terminal portions of penis about 1.2.

HABITATS. All specimens of Petrobius montanus sp. n. were collected in the forest

( Carpinus sp. , Fagus sp. , Fraxinus excelsior , Quercus robur ) among the stones.

DIFFERENTIAL DIAGNOSIS. Petrobius montanus sp. n. with the antennal flagellum devoid of scales belongs to the subfamily Petrobiinae ; with 2 + 2 eversible vesicles on urocoxites II–V, obtusangle urosternites, shoe-shaped paired ocelli, entire paramera on the

IXth abdominal segment, molar area of mandible with 1 or 2 inconspicuosus teeth to the genus Petrobius . Among the described species Petrobius montanus sp. n. is most similar to

P. crimaeus . Main morphological differences between these species are given in Table 3.

ETYMOLOGY. The new species is named after the predominant habitat type.

Figures

Figs 1–11. Petrobius montanus Kaplin, sp. n., holotype ♂ (1–3, 5, 7, 8, 11) and paratype