Stygiiulus illyricus ( Verhoeff, 1929 ) Vagalinski & Borissov & Bobeva & Canciani & Antić, 2022

Vagalinski, Boyan, Borissov, Simeon, Bobeva, Aneliya, Canciani, Giacomo & Antić, Dragan Ž., 2022, The mostly cavernicolous millipede genus Stygiiulus Verhoeff, 1929, stat. nov.: taxonomy, distribution and phylogenetic relationships (Diplopoda, Julida, Julidae), European Journal of Taxonomy 798, pp. 30-69 : 45-46

Stygiiulus illyricus ( Verhoeff, 1929) comb. nov.

Figs 10B , 11B , 13

Typhloiulus (Stygiiulus) illyricus Verhoeff, 1929: 20–23 , fig. 1. Typhloiulus (Stygiiulus) illyricus – Manfredi 1932: 81. — Strasser 1962: 20, 35–36, figs 11i, 36–37.

Typhloiulus illyricus – Verhoeff 1930: 17. — Antić et al. 2018: 263 , fig. 3.

Typhloiulus illyricus stygis – Verhoeff 1933: 15–17, figs 28–29, syn. nov.

Typhloiulus illyricus var. obscurus – Verhoeff 1933: 17 .

Typhloiulus illyricus var. obscura – Wolf 1934 –38: 515.

Material examined

SLOVENIA • 2 topotype juvs; Ocizla, Beško-Ocizeljski System (= Ocizeljska Jama Pit ); 19 Apr. 2012; T. Delić leg.; D. Antić det. 2018; IZB • 1 ♂, 1 ♀; Dane, Divača, Mejame Pit (= Med jamah, Medjama ); 22 Apr. 2014; M. Zagmajster leg.; D. Antić det. 2018; IZB . CROATIA • 1 ♂, 1 ♀; Istria, Ročko polje, Roč, Rabakova Cave ; 30 Jun. 2013; D. Šuperina leg.; D. Antić det. 2018; IZB • 1 ♀; same collection data as for preceding; 16 Apr. 2013; IZB .

Diagnosis

A species of Stygiiulus with normal mouthparts. Distinguishable from congeners by the combination of certain gonopodal characters ( Fig. 10B ), viz., a mostly straight promere, a mesomere with the apex bent frontad, and an opisthomere with a small but distinct posterior hump, a broad and deeply serrated velum, and a vestigial posterior solenomeral branch, this being completely fused to the velum.

Descriptive notes

ANTENNAE. 2.2 times as long as head and ca 1.8 times as long as H in males, and 1.7 times and ca 1.5– 1.55 times, respectively, in females; antennomere 5 ca 2.4 times as long as broad; antennomeres 2–5 subequal in length, ca 1.3–1.4 times as long as 6.

TARSUS OF MID- BODY LEGS. Ca 2.4 times as long as tibia and ca 2 times as long as apical claw. Mid-body legs ca 1.1 times as long as H in both sexes.

FEMALE SEXUAL CHARACTERS. Leg-pairs 1 and 2 considerably shorter than, but as thick as, following legs. Vulva ( Fig. 11B ) slightly compressed in the sagittal plane, mostly symmetric; median cleft deeper than in most congeners; each valve of bursa with several, mostly vertically arranged setae, 1–2 setae on side sclerites; operculum (op) distally markedly thickened, with a concave apical margin, exceeding bursa by slightly more than ¼ of total height of vulva, medio-laterally with two longitudinal rows of setae each side, with a bunch of setae on each latero-apical corner. Receptaculum seminis consisting of a fine, slightly bent, mesal tube (mt) ending in a small piriform ampulla (ma), and a somewhat shorter lateral tube (lt) ending in an ampulla (la) of similar shape and size as the former one.

Distribution

Known exclusively from caves and pits in the Istrian Peninsula in Croatia and the northwestern Dinarides in Slovenia ( Fig. 13 , green squares).

Remark

From Rabakova Cave, Verhoeff (1933) described the subspecies illyricus stygis, mentioning the possibility that the observed differences between the single male his description was based upon and the typical illyricu s were due to periodomorphosis, but he nevertheless opted to give a formal name to the new morph. Indeed, the gonopods he drew seem to be underdeveloped (see Verhoeff 1933: 20, fig. 28). Fortunately, we examined here one adult male from Rabakova Cave, whose gonopods appeared completely identical to the gonopods of the typical illyricus . We were even luckier to find that one of the juveniles from the type locality of the typical illyricus was a subadult male with unmodified first pair of legs. The gonopods of this subadult male are very similar to Verhoeff's (1933) drawing of the gonopods of the subspecies stygis. Based on these observations, it is clear that Verhoeff's stygis was actually a non-adult male or “Junior- Männchen” [junior male] – a term coined by Strasser (1971b), referring to typhloiulinine males with almost fully developed gonopods, but with non-modified first pair of legs and other, less conspicuous, underdeveloped external somatic structures (see also Vagalinski et al. 2015). We thus consider here S. illyricus stygis syn. nov. as a junior subjective synonym of the typical S. illyricus comb. nov.

Figures

Fig. 10. Left gonopods of species of Stygiiulus stat. nov., mesal views. A. S. ausugi (Manfredi, 1953) comb.nov.,topotype♂(NHMD).B.S.illyricus(Verhoeff,1929)comb.nov.,redrawnfromVerhoeff (1929). C. S. insularis (Strasser, 1938) comb. nov., redrawn from Antić et al. (2018). D. S. maximus (Verhoeff, 1929) comb. nov., redrawn from Verhoeff (1930). E. S. seewaldi (Strasser, 1967) comb. nov., redrawn and modified from Strasser (1967). F. S. tobias (Berlese, 1886) comb. nov., ♂ from Grotta [Cave] del Subiolo (NHMD). Abbreviations: do = distal outgrowth of velum. Drawn not to scale.

Fig. 11. Left vulvae of species of Stygiiulus stat. nov. (A–D) and representatives of (other) Julini/ Leptoiulini (E) and Typhloiulini/blind Julini/Leptoiulini in caudal, somewhat mesal views. A. S. ausugi (Manfredi, 1953) comb. nov., ♀ from Grotta [Cave] del Calgeron (NHMD). B. S. illyricus (Verhoef, 1929) comb. nov., ♀ from Rabakova Cave (IZB). C. S. insularis (Strasser, 1938) comb. nov., topotype ♀ (CBSS). D. S. tobias (Berlese, 1886) comb. nov., ♀ from Grotta [Cave] del Subiolo (NHMD). E. Leptoiulus cf. trilineatus(C.L. Koch, 1847), ♀ from Belasitsa Mtn, Bulgaria. F. Serboiulus spelaeophilus Gulička, 1967, ♀ from Vodni Pech Cave (NMNHS). G. Typhloiulus (Inversotyphlus) lobifer Attems, 1951, ♀ from Minjera-Bauxite Mine (IBER). H. Typhloiulus (s. str.) strictus (Latzel, 1882), ♀ from Kunino (IBER). Abbreviations: at = anterior tube; la = lateral ampulla; lt = lateral tube; ma = median ampulla; mt = median tube; op = operculum; pa = posterior ampulla; pt = posterior tube. Scale bar = 0.2 mm.

Fig. 13. General distribution of the species of the genus Stygiiulus stat. nov.