ON THE EVOLUTIONARY STATUS OF ENANTIULUS NANUS ACUTUS ( ATTEMS , 1929 ) ( JULIDAE , DIPLOPODA )

The diplopod genus Enantiulus Attems, 1894, comprises the following species: Enantiulus armatus (Ribaut, 1909), E. austriacus (Verhoeff, 1896), E. dentigerus (Verhoeff, 1901), E. karawankianus (Verhoeff, 1908), E. nanus (Latzel, 1884), E. simplex (Verhoeff, 1926), E. tatranus (Verhoeff, 1907), and E. transsylvanicus (Verhoeff, 1899) (R e a d 1990). The main generic characters of this group of species are: pale colour, reduced number of eye rows; metazonites with setae; gonopods with no flagellum; mesomerite forked; brachite with cuticular spines; vulvae with two sac-like ampullae; and "tail" pointing downwards. Within this genus the most widespread species is Enantiulus nanus (from Denmark, France, Germany, Austria, Switzerland, Holland, Italy, Poland, Hungary, Serbia, Romania, Bulgaria, Ukraine, etc.). At t ems (1929) described the subspecies E. nanus acutus from Mt. Sar Planina (Serbia). S t r asse r (1971) accepted this subspecies as a valid taxon; however, Rea d (1990) in his review of Cylindroiulini, could not explain the status of E. nanus acutus; however, C e u c a (1992) ommitted this subspecies in his review of the diplopods of the Balkan Peninsula, but without any explanation. Additional confusion arose when M a uri e s et al. (1997) retained a subspecific level for E. nanus acutus. It is evident that taxonomic status of this analysed subspecies is still unclear. Therefore, we tried to clarify the relationships between the nominal subspecies E. nan us nanus and its subspecies E. nanus acutus, based on the study of the material from the collection of the Institute of Zoology, Faculty of Biology, University of Belgrade, as well as on the analysis of the relevant literature data.


ON THE EVOLUTIONARY STATUS OF ENANTIULUS NANUS ACUTUS
. S. E. Makarov, B. M. Mitic and V. T. Tomic, Institute of Zoology, Faculty of Biology, University of Belgrade and Centre for Biospeleology in Southeast Europe, 11000 Belgrade, Serbia and Montenegro.
Within this genus the most widespread species is Enanti- ulus nanus (from Denmark, France, Germany, Austria, Switzerland, Holland, Italy, Poland, Hungary, Serbia, Romania, Bulgaria, Ukraine, etc.).At t ems (1929) described the subspecies E. nanus acutus from Mt. Sar Planina (Serbia).S t r asse r (1971) accepted this subspecies as a valid taxon; however, Rea d (1990) in his review of Cylindroiulini, could not explain the status of E. nanus acutus; however, C e u c a (1992) ommitted this subspecies in his review of the diplopods of the Balkan Peninsula, but without any explanation.Additional confusion arose when M a uri e s et al. (1997) retained a subspecific level for E. nanus acutus.It is evident that taxonomic status of this analysed subspecies is still unclear.
Therefore, we tried to clarify the relationships between the nominal subspecies E. nan us nanus and its subspecies E. nanus acutus, based on the study of the material from the collection of the Institute of Zoology, Faculty of Biology, University of Belgrade, as well as on the analysis of the relevant literature data.Discussion: In his original description of the subspecies acutus, At t ems (1929) found that the main (and only) difference between the nominal subspecies and the subspecies acutus was the shape of the posterior lobe of opisthomerite.

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This same author could not establish any other relevant difference between the two analysed forms.
In our samples, specimens from Mt. Sar Plan ina (10 km away from the type-locality of E. nanus acutus ) have the opisthomeral lobe slightly pointed (Fig. 4) similar to the original description (Fig. 6) by Attems.Additionally, S to j a low s k a (1961) presented excellent drawings of the gonopods of E nanus (from Poland), bearing pointed lobes (Fig. 8).Another specimen from Mt. Kopaonik has a more or less rounded lobe, with a minute triangular projection on the anterior side of the lobe (Fig. 5).Such a rounded lobe is very similar to that character in specimens from Austria (A t t ems 1929) (Fig. 5) and from Germany (S c hub art 1934) (Fig. 7).Therefore, it is clear that the structure of the opisthomeral posterior lobe is highly variable, and not subspecies-specific; it reflects only the degree of the intrapopulation variability.The brachite is uniform, without significant differences in comparison to specimens from both West and East Europe.Furthermore, all specimens, both from literature data and from our samples, have a single lateral branch of meso me rite.However, in specimens from Mt. Sar Planina the height of mesomerite is almost the same as the height of promerite, the former being proximally pointed and triangular (Fig. 1).A similar structure of mesomerite was found in the specimen from Germany (S c h u bar t 1934) (Fig. 7).On the other hand, specimens from Mt. Kopaonik and Mt.Avala have a rounded mesomerite, slightly lower than opisthomerite (Fig. 2), and similar to E. nanus from Poland (S t 0 j a low s k a 1961) (Fig. 8).This means that the normal variability of the shape of mesomerite varies from the rounded to the triangular proximal part.As far as body structure is concerned (e. g. structures of leg-pair I, somites, head, shape of penis, etc.) there exist no significant differences between the analysed specimens (i.e. between the subspecies E. nanus nanus and E. nanus acutus).In that case, the latter name is a synonym of E. nanus.(Latzel, 1884).1. Promerite and mesomerite, caudal view; male from Mt. Sar Plan ina, Serbia; 2. Promerite and mesomerite, caudal view; male from Mt. Kopaonik, Serbia; 3. Opisthomerite, lateral view; male from Mt. Sar Planina; 4. Opisthomerite, lateral view; male from Mt. Kopaonik; 5. Oisthomerite, lateral view; male from Gratz (after A t t ems 1929); 6. Opisthomerite, lateral view; male from Mt. Sar Planina (after At t ems 1929); 7. Gonopod complex, lateral view; male from Germany (after S c hub art 1934); 8. Gonopod complex, lateral view; male from Poland (after S t 0 j a low s k a 1961).