Chthonius heterodactylus Tömösváry, 1882

Chthonius heterodactylus Tömösváry 1882a: 241; Szalay 1968: 35; Novák & Dányi 2018: 306, 319 Červená et al. 2020a: 221;

WPC 2023. Chthonius Rayi L. Koch: Tömösváry 1882a: 240 (misidentification). Chthonius tetrachelatus (Preyssler, 1790): Daday 1889a: 134; Daday 1889a: 190 (misidentification). Chthonius diophthalmus Daday 1889a: 134; Novák 2012: 60; Novák 2013a: 122; Novák & Dányi 2018: 306. Chthonius (Chthonius) diophthalmus: Novák 2012: 60; Novák 2013a: 122. Chthonius (Chthonius) heterodactylus: Szent-Ivány 1941: 86; Beier 1963a: 27; Harvey 1991: 148; Kárpáthegyi 2006: 116;

Christophoryová et al. 2011b: 36; Novák 2012: 60; Harvey 2013; Novák 2013a: 122–123; Gardini 2014: 107–114; Novák

2017a: 37; Novák 2018: 99.

Occurrence: Czech Republic, Germany, Hungary, Poland, Romania, Slovakia, Ukraine (Gardini 2014).

Known localities in Hungary: Kőkapu (Kárpáthegyi 2006). Miskolc: Forrás Valley; Nagyvisnyó: Leány Valley (Novák 2012); Szentdomonkos: Simon-tó-tető; Szögliget: Ménes Valley (Novák 2013a). Aggtelek: Bíbic Dolina (E-side); Jósvafő: Farkaslyuk (E-side); Mikóháza: Fekete Hill; Szin: Háló Valley (Novák 2018).

New data: Felsőhámor: Dolka Ridge, beech forest, sifted, 08.08.2010, leg. JN (HNHM Pseud-1035: 1♀) .

Habitat preference: in Slovakia, Krajčovičová et al. (2016) found the species in moss, Christophoryová et al. (2017c) reported it from dead wood, and Jászayová & Jászay (2022) reported it from the following habitats: beech and fir flowery forest with the presence of maple, maple-beech mountain forest, floodplain alder forest with beech and grey alder, beech primeval forest with silver fir and European spruce. In Hungary it has been earlier reported from beech forest (Novák 2013a, 2018), from beech-hornbeam and oak-hornbeam forest, from rock faces from beech trees (Novák 2018). During the present study it was found in the leaf litter of beech forest.

Remarks: this species was described by Tömösváry (1882a) from localities across the historical Hungary which now belong to Slovakia (Bártfa = Bardejov, Szinnaikő = Szninszky Kamen) and Romania (Zilah = Zalău). Chthonius heterodactylus was redescribed by Gardini (2014), who also synonymysed Chthonius diophthalmus Daday, 1889, C. (C.) orthodactylus gracilis Beier, 1935, C. (C.) ksenemani Hadži, 1939, and C. (C.) leruthi Beier, 1939 with it (Gardini 2014). From Hungary, this species is known from elements of the Northern Hungarian Mountains (Kárpáthegyi 2006; Novák 2012, 2018). In the Hungarian material I have observed specimens without an epistome and only one pair of preocular microsetae, which according to Gardini (2014) represent character states that are regarded as intraspecific variation. In some male specimens the genital opening was flanked by a row of setae on each side, whereas normally these setae are scattered on each side (Gardini 2014).