The mostly cavernicolous millipede genus Stygiiulus Verhoeff, 1929, stat. nov.: taxonomy, distribution and phylogenetic relationships (Diplopoda, Julida, Julidae) Author Vagalinski, Boyan CF6A5691-5C32-4CFF-9EB6-045DEB16F289 Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, 2 Gagarin Street, 1113, Sofia, Bulgaria. boyanv84@gmail.com Author Borissov, Simeon C035E1AC-D4FB-4A3F-8B38-5D38A9665E88 Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, 2 Gagarin Street, 1113, Sofia, Bulgaria. borissovsb@gmail.com Author Bobeva, Aneliya 0F4EA315-46BE-49AC-8FB4-CF710C5B2451 Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, 2 Gagarin Street, 1113, Sofia, Bulgaria. aneliabobeva@gmail.com Author Canciani, Giacomo 4BB21FD2-15C8-44BD-907A-4498D7D02A15 Jamarski Klub Kraški Krti / G. S. Talpe del Carso, loc. San Michele del Carso / Vrh, I- 34070 Savogna d’Isonzo (GO), Italy. & Associazione Speleologica Forum Julii Speleo, Via Carraria 99, I- 33043 Cividale del Friuli (UD), Italy. giacomo.canciani90@gmail.com Author Antić, Dragan Ž. 2368C980-2042-4137-998D-8C91E4337185 University of Belgrade - Faculty of Biology, Institute of Zoology, Studentski Trg 16, 11000 Belgrade, Serbia. & Serbian Biospeleological Society, Trg Dositeja Obradovića 2, 21000 Novi Sad, Serbia. dragan.antic@bio.bg.ac.rs text European Journal of Taxonomy 2022 2022-02-28 798 30 69 http://dx.doi.org/10.5852/ejt.2022.798.1669 journal article 20422 10.5852/ejt.2022.798.1669 31fec661-5dac-4626-856d-4ba4680efee7 2118-9773 6323002 50692D26-A41C-4F85-B207-A6747FD07470 Serboiulus spelaeophilus Gulička, 1967 Fig. 11F Material examined BULGARIA1 ♀ topotype; Belogradchik District , Dolni Lom , Vodni Pech Cave ; 25 Feb. 2000 ; B. Petrov leg.; guano-clay ; NMNHS . Descriptive notes Vulva ( Fig. 11F ). Strongly compressed in the sagittal plane, mostly symmetric; bursa with a shallow and very narrow median cleft; each valve distolaterally with a few setae; operculum (op) with a deeply concave apical margin, just slightly higher than bursa, distally bearing long setae. Receptaculum seminis consisting of two similarly narrow and twisted tubes – a lateral (lt) and a mesal one (mt), each forming an ovoid ampulla at bottom, the lateral one (la) being somewhat larger than the mesal one (ma).