New species of bristletails of the family Machilidae (Microcoryphia) from caves in Abkhazia and Ukraine.

Two new species of bristletails of the family Machilidae are described from caves in the Western Caucasus (troglophile Coryphophthalmus troglophilus sp. nov.) and in the Eastern Carpathians (trogloxene Trigoniophthalmus ukrainensis sp. nov.). The main morphological adaptations of C. troglophilus sp. nov. to life in caves include green eye color; weak body pigmentation; well-developed arolium and claws; relatively long cerci, tarsae and tibiae of the hind legs; long apical needles of the urostyli; large sublateral spines on urocoxites IX. C. troglophilus sp. nov. resembles C. abchasicus (Kaplin, 2017), but they are distinguishable in color of eyes, ratio of eye contact to length, length of cerci, structures of the labial palps, legs, urocoxites IX, ovipositor, and parameres. Trigoniophthalmus ukrainensis sp. nov. has no recognized morphological adaptations to life in caves. This species resembles T. alternatus (Silvestri, 1910), but they are easily distinguished in the number of annuli in distal chains of flagellum, ratio of width to length of paired ocelli, chaetotaxy of male maxillary and labial palps.

Taxonomic review of the genera Trigoniophthalmus Verhoeff and Coryphophthalmus Verhoeff (Archaeognatha, Machilidae) with descriptions of two new species of the genus Coryphophthalmus from Serbia.

A redescription of Trigoniophthalmus Verhoeff, 1910 and descriptions of its subgenera Trigoniophthalmus s. str. and Silvestrius subgen. nov., along with revalidation and redescription of the genus Coryphophthalmus Verhoeff, 1910, and descriptions of its subgenera, Coryphophtalmus s. str. and Verhoeffius subgen. nov., are given on the basis of comparative analysis of the main morphological features and distribution of 33 described species. Coryphophthalmus obscurus sp. nov. and C. serbicus sp. nov., in the subgenus Verhoeffius subgen. nov., are described from Serbia. Coryphophthalmus obscurus sp. nov. differs from other species of this subgenus in the relatively short body and antennae, elongated compound eyes, tarsus with numerous spine-like setae and ovipositor with more divisions than other species. Coryphophthalmus serbicus sp. nov. is most similar to C. longitarsus (Kaplin) from Abkhazia. The main differences between these species consist in the line of eye contact, structure of the paired ocelli, labial palps, legs, urocoxites IX, ovipositor and male parameres.

A new species of the genus Allopsontus Silvestri (Archaeognatha: Machilidae) from the Eastern Kazakhstan.

A new bristletail species, Allopsontus ilyai sp. nov., is described from Eastern Kazakhstan. It is most similar to A. smelyanskii Kaplin described from Orenburg Region (Russia). The main differences between these species consist in the color of the eyes, structure of the paired ocelli, legs, urosternites, urocoxites VIII and IX. A key to the subgenera and species of the genus Allopsontus from Kazakhstan is given.