Taxonomic notes on two endemic geometrine genera from Middle Asia (Lepidoptera: Geometridae, Geometrinae) Author Viidalepp, Jaan Estonian University of Life Sciences, Kreutzwaldi, 5 D, EE- 51006 Tartu, ESTONIA Author Kostjuk, Igor 0000-0002-8656-5330 Zoological museum, Kyiv National Taras Shevchenko University, Volodymyrska str. 60, UA- 01601 Kyiv, UKRAINE. ikostjuk @ univ. kiev. ua; https: // orcid. org / 0000 - 0002 - 8656 - 5330 ikostjuk@univ.kiev.ua text Zootaxa 2021 2021-10-13 5052 1 137 144 journal article 4026 10.11646/zootaxa.5052.1.9 07baf883-204c-4608-a8b3-924711319ef3 1175-5326 5566148 3E6DA6AB-32EB-473A-BD67-C8C59D4357BF Hierochthonia Prout, 1912 and “ H .” alexandraria Prout, 1912 Prout diagnosed the genus Hierochthonia ( Type species: Microloxia pulverata Warren, 1901 ) using external characters as antennae bipectinate up to the last apical segments; hindwing with the subcostal vein fused with the fore margin of the discal cell near to its end; hindtibia provided with one pair of spurs (Prout 1912: 204). Hausmann (1996) redescribed the genus Hierochthonia using H. pulverata Warren and H. semitaria Püngeler. Comparison of the characteristics of H. alexandraria (also Figs 9–11 , 23 ) with those of southern species ( Figs 7, 8 , 22 ) indicates the following differences. Both Hierochthonia-- H. pulverata and H . semitaria-- possess long, flat postvaginal lamellae and roundish lateral sclerites attached to the ostium in female genitalia ( Hausmann 1996 , Figs 144, 145). These structures are missing in “ H.” alexandraria and “H.” petitaria females ( Figs 24, 25 ). The valva in male genitalia of typical Hierochthonia has a medial harpe ( Figs 22 ), and aedeagus is spoon shaped (distally dilated) with a complex apical sclerotization. However, “ H.” alexandraria has a tubular aedeagus with two thorn shaped cornuti on the vesica, and a simple valva ( Fig. 23 ). Prout (1912) stressed the peculiar venation of hindwing with Sc free when characterizing “ Hierochthonia ” alexandraria . We use this synergy of differences in wing venation and in male and female genitalia characteristics to separate “ H .” alexandraria in a new genus of its own, Ratsa Viidalepp & Kostjuk , gen. nov . will be described below for this species.