Xylosteus caucasicola was described by Plavilstshikov (1936) in his brilliant work on Cerambycidae fauna of the former Soviet Union. Since then many authors have retained the taxon as a valid species: Danilevsky and Miroshnikov (1985), ©vácha and Danilevsky (1988) (although no reliable differences in larval morphology between X. caucasicola × X. bartoni × X. spinolae were found), Althoff and Danilevsky (1997), Miroshnikov (1998) (a very detailed revision of this taxon), and most recently in Danilevsky (2000). According to Sama (1993) the species Xylosteus spinolae Frivaldszky, 1838 forms three geographic subspecies. The nominate Xylosteus spinolae spinolae Frivaldszky, 1838 is confined to Bulgaria and Romania, Xylosteus spinolae rufiventris (Germar, 1845) (described as Rhagium rufiventre) occurs in SW and S Europe, and finally Xylosteus spinolae caucasicola Plavilstshikov, 1936 occurs in N Turkey and the Caucasus Mts. However, later a thorough study of the type material revealed a new synonymy: Rhagium rufiventre Germar, 1845 is a new synonym of Xylosteus spinolae Frivaldszky, 1838 (Sama, personal communication). It has been believed that the subspecies caucasicola was only confined to the Caucasus region. However, recent studies have shown that the taxon caucasicola is distributed continually from the Caucasus region, through all of the Pontic mountain range (northern Turkey) reaching the European Turkey (Sama and Rapuzzi, 1999). Therefore, Xylosteus spinolae caucasicola Plavilstshikov, 1936 must be regarded as a new SUBSPECIES for Europe. However, in Danilevsky (2000) the same data (Sama and Rapuzzi, 1999) was interpreted as Xylosteus caucasicola Plavilstshikov, 1936: a new SPECIES for Europe. Most recently Miroshnikov (2000) has described a population occurring in Bolu (NW Turkey) as a new taxon: Xylosteus kadleci, stating that the taxonomic status of this taxon still remains to be clarified (X. kadleci might only be a subspecies of X. caucasicola). The beetle in the picture was collected in Bolu (NE Turkey) where it develops in Abies. Dead stumps of smaller diameter is the preferred larval substrate. The species is nocturnal. An interesting experiment was performed by our colleague Ladislav Karaus. In Bolu (NE Turkey) he captured a female of this species and placed it into a wire cage. The cage was placed on top of a fir tree stump and covered by fresh fir branch. During the following night he inspected the trap several times and captured about 20 males that had been attracted to it. In our opinion this experiment implies that a female-released long range sexual pheromone is involved in this species' reproduction strategy. In general we believe that Lepturinae ovipositing and developing in rotten wood use long range sexual pheromones for the larval substrate is physiologically inactive and difficult to detect. On the other hand xylophagous longhorn beetles developing in recently dead wood can rely on volatile chemicals still emitted by the recently dead trees and consequently no long range sexual attractant is necessary as the beetles meet on the larval substrate.
MH & MR © August 24, 2007
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