Sibiriulus Gulička, 1963

Mikhaljova, Elena V., Nefediev, Pavel S., Nefedieva, Julia S., Sakhnevich, Miroslava B. & Dyachkov, Yuri V., 2014, Review of the millipede genus Sibiriulus Gulička, 1972, with descriptions of three new species from Altai, Siberia, Russia (Diplopoda, Julida, Julidae), Zootaxa 3866 (1) : -

Genus Sibiriulus Gulička, 1963

Cylindroiulus Verhoeff, 1894 subgenus Sibiriulus Gulička 1963: 518 –519.

Allajulus Koch, 1847 subgenus Sibiriulus Gulička, 1963 according to Hoffman 1980: 110. Sibiriulus Gulička, 1963 (full genus): Lokšina & Golovatch 1979: 387.

Type species: Cylindroiulus (Sibiriulus) dentiger Gulička, 1963 , by original designation.

Diagnosis. The main distinguishing characters of this genus are as follows. Body pigmented; eye patches present; epicranial setae present; male genae unmodified; gnathochilarium normal, with a group of short setae approximately in the middle of the stipites, sensory bacilli at distal end of antennomere 5 and 6 few, forming no complete corolla; caudal edges of metazonites with setae; telson with a caudal not very long projection of epiproct (including a tiny claw-shaped process); male leg pair 1 unciform; male leg pairs 2 and 7 normal; gonopods consisting of pro-, meso- and opisthomere; pro- and mesomere closely attached to each other; opisthomere somewhat moved caudad (but not so far as in Cylindroiulus ); promere flattened, caudally papillate, with a flagellum whiplike but without remnants of a telopodite; mesomere completely flattened (in S. multinicus ) or mesomere frontally with plate; front surface of mesomere densely papillate; mesomere apex a simple or modified (with fovea, with protuberance, near hook-shaped, flattened laterally); coxite of opisthomere distinct; coxosternal region generally poorly developed; solenomere broad; velum present; phylacum present (as slender process) or absent.

By the unmodified male genae, the absence of complete corolla of sensory bacilli at distal end of antennomere 5, unciform leg pair 1 of male, normal leg pairs 2 and 7 of male, presence of metazonital setae, ozopores, lying behind suture between pro- and metazona without touching it, distinct coxite of gonopod opisthomere, flattened gonopod promere, well-developed interior parabasal spine of gonopod opisthomere, the genus seems particularly related to Pacifiiulus Mikhaljova, 1982 from the Asian part of Russia. However, it differs from this genus chiefly by the absence of remnant of a telopodite on gonopod promere, shape of gonopod mesomere (not spoon-shaped as in Pacifiiulus ) and broad gonopod opisthomere.

On the other hand, Hoffman (1980) in his classification of millipedes listed Sibiriulus in the tribe Cylindroiulini . Read (1990) removed Sibiriulus from this tribe and noted that some of the characters of Sibiriulus species resemble those of certain Leptoiulus species. However, as we can see, species of Sibiriulus differ from them chiefly by the absence of a large basal outgrowth of the gonopod promere, the shape of the gonopod mesomere (with frontal plate and modified apex) and the small phylacum.

Description. Length of males 11–17 mm, vertical diameter 0.5–0.9 mm. Length of females 13–18.5 mm, vertical diameter 0.9–1.2 mm. Coloration from dark brown with or not reddish tinge to pale brown. Body segments, collum and head may be variably patterned. Ventral part of body lighter. Thin, dark axial line discernible on dorsum. Legs brown to pale or yellowish. Eye patches black. Antennae brown and dark brown.

1+1 epicranial setae in a transverse row. Supralabral setae 2+2 (as rule) in a transverse row, labral ones 4+7, 5+6, 6+7, 7+7, 7+8, 8+8, 8+9, 10+8, 10+10. Labrum tridentate. Eye patches roundly subquadrate, composed from 20 to 30 ocelli in adults. Antennae medium-sized, rather slender and clavate. Antennomeres 5 and 6 with an incomplete distodorsal corolla of several sensory bacilli. Gnathochilarium distally with two setae on outer edge of each stipites and with one seta closer to medial portion and with micropapillate low knob as well as with a group of short setae approximately in the middle of the stipites. Each lamella lingualis with 3–4 setae arranged longitudinally; length of setae increasing towards apex of lamellae linguales. Genae unmodified. Collum without peculiarities.

Body subcylindrical, slender, somewhat compressed laterally. Prozonite and metazonite separated by distinct suture. Prozonites smooth. Metazona with striae not reaching hind margin dorsally and laterally, but reaching hind margin ventrally. No more than 9 striae on metazonital surface between dorsal midline and ozopore. Transverse row of sparse, thin, relatively short setae at hind edge of metazonites. Metazonital setae gradually growing longer and denser toward telson. Ozopores small, lying behind suture between pro- and metazona without touching it. Telson with a short, caudal subcylindrical projection of epiproct carrying tiny claw-shaped process directed caudad and somewhat ventrad or caudad. Density of telson pubescence varied. Anal scale subtriangular, setose only along caudal edge.

Legs slender. Claw at base with a thin, setiform accessory claw ventrally. Sole pads in male legs (on tibia and postfemur) present or absent. Male leg pair 1 unciform, low papillate apically, with 2-segmented telopodites carrying strong setae ventrally. Telopoditomere 2 with rounded low knob-shaped outgrowth. The telopoditomere 1 bears greater number of setae than the telopoditomere 2 (as rule). Each coxa of leg pair 1 with a distal seta. Leg pair 2 unmodified. Penes flattened, relatively short, apically double, without setae. Male leg pair 7 normal. Ventral margins of body segment 7 with rounded lobes touching in midline. However, the two gonopod promeres close the gonopodial aperture and are the only parts of the gonopods visible in ventral view.

Gonopods consisting of pro-, meso- and opisthomere. Pro- and mesomere closely attached to each other; opisthomere somewhat moved caudad. Coxite of opisthomere distinct. However, coxosternal region generally poorly developed. Promere flattened, caudally papillate, with a flagellum as whip but without remnants of a telopodite. Mesomere completely flattened (in S. multinicus ) or mesomere frontally with plate. Front surface of mesomere densely papillate. Mesomere distal part simple (in S. multinicus ) or modified (with an apical fovea, with protuberance, near hook-shaped). Opisthomere with interior parabasal spine and with or without massive or short inner process. Solenomere broad. Velum present. Phylacum present (as slender process) or absent.

Vulvae oblong, with strong setae. Operculum higher than bursa, with apical incision and with setae arranged in two longitudinal rows, apical setae longest. Apex of bursa with pair of hyaline lobes, one on each side of the median cleft in the posterior median plate. Lateral and mesal bursal sclerites together with 4–18 setae. Posterior median sclerite of the bursa with 9–20 setae arranged in two more or less regular rows, apical setae longest. Number of vulval setae positively correlated with body size.

Included species. S. profugus (Stuxberg, 1876) , S. altaicus Gulička, 1972 , S. multinicus Mikhaljova, 2001 , S. rectangulus Mikhaljova, 2009 , S. latisupremus sp. nov., S. aktashensis sp. nov., S. baigazanensis sp. nov.

Distribution (Map). Russia: West and Southwest Siberia, East Kazakhstan.