Sandy yellowish-grey moths with wing span 25–26 mm. Dark irroration stronger on wings, forewing postmedial fascia broader at costa; wing markings are less reduced than in R. vastaria. Underside of wings almost monotonous, greyish.

The genus Rhodostrophia is characterised by their quadripectinate male antennae (i.e. there are two pairs of long rami on each antennomere) and by the presence of two accessory cells in the forewing venation. All species of Rhodostrophia have the number of their hind tibial spurs reduced, with exception of R. jacularia Hübner, R. vastaria, R. tabestana Trusch & Hausmann and the new species Rhodostrophia crypta sp. n. Wings of R. vastaria and R. crypta, sp. n. are scaled yellowish-grey, forewings with fragmented postmedial and antemedial fasciae.

Rhodostrophia vastaria and Rhodostrophia crypta, sp. n. are superficially similar but differing in characteristics of male and female genitalia, as discussed below.

Rhodostrophia crypta, sp. n. This new species is characterized with a wing span of 25–26 mm (Fig. 1a, b). The Uch-Aral male is grey with a conspicuous dark grey pattern and dusting (Fig. 1a); its hindwing postmedial line is outwardly dentate at the vein M3 and the forewing medial area seems relatively broader. West Kazakh moths (Fig. 1c, d) of R. vastaria are evenly sand-coloured, yellowish-grey and with sparse grey maculation. The sandy grey ground colour of the moths from the Balkhash region is more intensively covered by brown spots and the postmedial line is more suffused on hindwings (Fig. 1a, b).

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b

c

d

Figure 1.

Rhodostrophia moths.

a: Rhodostrophia crypta, sp. n. (Holotype, male, IZBE)   
b: Rhodostrophia crypta, sp. n. (Paratype, female, ZMKU)  
c: Rhodostrophia vastaria Christoph, male, Ustjurt plateau, Sai-Utjos, Shovkoon leg.  
d: Rhodostrophia vastaria Christoph (Lectotype, female, ZISP)  

The distal edge of the valva in the male genitalia is roundly bulged at the saccular corner in R. vastaria (Fig. 2a; Hausmann 2004: Fig. 174b), but it is straight in R. crypta, sp. n. (Fig. 2b). Female genitalia of moths are also different; moths of western population have the seventh segment of the abdomen and the tubular sclerotisation of the ductus bursae distinctly longer in moths of the western population (Fig. 3a) and the forked sclerite in the corpus bursae is also larger in western moths than in those moths from the eastern Kazakh population (Fig. 3b).

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b

Figure 2.

Male genitalia and aedeagus of Rhodostrophia spp.

a: Rhodostrophia vastaria, male, Ustyurt plateau, slide 114, Shovkoon  
b: Rhodostrophia crypta, sp. n. (Paratype, male, slide 8976 IZBE)  

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b

Figure 3.

Female genitalia of Rhodostrophia spp.

a: Rhodostrophia vastaria (Lectotype, female, gen. prep. 634/2005 Trusch, ZISP)  
b: Rhodostrophia crypta, sp. n. (Paratype, female slide 488, ZMKU)  

The differences in male and female genitalia structures and wing pattern between the western and eastern Kazakh populations justify the separation of the Balkhash lake shore populations as Rhodostrophia crypta Viidalepp & Kostjuk, sp. n.

Rhodostrophia jacularia (Hübner) has a very different, clear and contrasting wing pattern but similar male genitalia (with the distal margin of the valva smoothly rounded) and R. tabestana (Trusch and Hausmann 2007) has quite similar wings and colouration, but the distal margins of valvae are not straight; rather they are slightly concave. Genetically nearest species: Rhodostrophia jacularia (3.7%). The distally truncate shape of valva and the presence of a cornutus on the vesica in R. jacularia, R. crypta, sp. n., R. vastaria and R. tabestana allow them to be combined together in the Rhodostrophia jacularia species group.

The species name "crypta", as a noun, is a derivative from "cryptic" ~hidden.

The moths of the new species were collected in steppe landscapes.

The distribution area of Rhodostrophia vastaria is fragmented between Turkmenbashi in Turkmenistan, the Ustjurt plateau in western Kazakhstan and the southern Urals (Fig. 4). Rhodostrophia crypta, sp. n. is an eastern Kazakh species. Both species do not appear in the recent review of Chinese Rhodostrophia (Cui et al. 2019).

Figure 4.  

Distribution map of R. vastaria and R. crypta, sp. n.