Balkanopetalum Verhoeff, 1926

Stoev, Pavel & Enghoff, Henrik, 2003, Systematics, phylogeny and biogeography of genus Balkanopetalum Verhoeff, 1926 (Diplopoda: Callipodida: Schizopetalidae), Zootaxa 272 (1), pp. 1-26 : 4-5

Genus Balkanopetalum Verhoeff, 1926

Balkanopetalum Verhoeff, 1926: 57

Typus generis: Balkanopetalum armatum Verhoeff, 1926 .

Diagnosis: Moderately large callipodidans (body length 44­68 mm, diameter 2­3 mm). General body coloured from dark brown to pale brown­yellowish; metazonites with a dark brown stripe along posterior margin, stripe getting paler at midbody, lacking on anterior pleurotergites. Adult body usually composed of 53­56 pleurotergites 1. (Following the advice of Enghoff et al. (1993) we use the term "pleurotergite" instead of "segment" which has traditionally been used by millipede taxonomists. Please notice that the number of pleurotergites is one less than the traditional numbers of "segments" because the telson is not included in the pleurotergite count). Male head with deep, hairless anterior concavity; often with numerous bristles between the concavity and the labrum; females with bristles covering almost the whole surface of the head; ocellaria black, triangular; antennae usually reaching posterior margin of the eight pleurotergite when folded back. Trunk pleurotergites with well developed but not very pronounced crests, crests somewhat flattened dorsally, finger­like (= Fingerwülste, in Verhoeffís works) (exception: B. graecum ), crests similar in males and females. Ozopores starting on sixth pleurotergite, placed between the crests, or at their base; third pleurotergite in females much larger than that of males.

Pleurotergal chaetotaxy variable between species, a general pattern at genus level not discernible. Posterior seta b often situated exactly behind anterior seta a; all setae usually in posterior position on the 7th pleurotergite (in a specimen of rhodopinum all setae were in posterior position on 8th pleurotergite); collum and the first six pleurotergites often with unequal numbers of setae on each hemipleurotergite (11+7; 8+10; 9+8). The number of posterior setae on 7th pleurotergite varies from 6+6 ( rhodopinum , beskovi ) over 7+7 ( graecum , armatum , bulgaricum ) to 8+8 ( petrovi ) — there are, however, exceptions from these “normal” numbers. 1

Prefemur of male 7th leg­pair variable. 2

Male gonopods without a sternal process; coxae with an anterior coxal process with two tines (these sometimes so deeply separated that they appear as individual spinelike processes), sometimes with an additional subanterior process and always with a posterior process, the latter as long as a 2/3 of the femoroidal length, basally densely setose; coxa always covering the basal part of the femoroid (this part of the coxa is referred to as “Lappen”, in Verhoeff, 1926); main stem of femoroid elongated (exception: graecum ); apical part curved or straight; ovoid plate of variable shape; a distal process of variable shape, but always black­coloured, emerging at the apical part of the femoroid; solenomerite bifid or trifid, seminal groove always ending at the upper (dorsalmost) branch.

Habitats: All species are strict troglo­ and petrophiles, often found in the very inner passages of caves and deserted mine galleries. Sometimes they also occur superficially under stones outside caves. The only member of the genus, which might at present be considered as a true troglobite is rhodopinum .

Distribution: Bulgaria: Western Stara Planina Mts., Rhodopi Mts., south Pirin Mts., Slavyanka (Orvilos) Mts. Greece: Rhodopi Mts. (Fig. 22). All species are allopatric, the smallest distance between the ranges of two species being that between graecum and petrovi (50 km).