Infiltration of the Eumediterranean fauna (Hemiptera: Psylloidea) into Caucasus and its historical reasons

Author: Arnold Gegechkori
Keywords: Mediterranean regions, the Caucasus, Psyloidea, infiltration of the fauna.
Annotation:

• The fauna of the Caucasus, according to some authors, belongs to the Mediterranean subrealm of the Palaearctic biogeographical realm (Wallace, 1876, Menzbier, 1882, Kryzhanovsky 1965 etc.). This opinion is incorrect from both phytogeographical and zoogeographical points of view. The indicator of the Mediterranean proper countries’ biota is the maquis flora. In the recent geological epoch, according to paleogeographical and paleoclimatological events, first of all regarding to Messinian crisis (Pliocene time) only very poor derivate forms of maquis vegetation survived in the extremely local refugia in the western part of South Caucasus (Abkhazia and Adzharia in West Georgia). • From the solution above mentioned problem the author used psyllid fauna (Hemiptera: Psylloidea). the results of investigation of Psylloidea are given in author’s fundamental monograph - ,,Psyllids of the Caucasus” (gegechkori, 1984) and were delivered in some international conferences. The Caucasus the crossroad region between Europe and Asia. Psyllids of this region is one of the best studied in the Palaearctic (Burckhardt & Onucar, 1993, Burckhardt & Lauterer 1993). • Like Olea europae (Oliaceae) and Arbutus spp. (Ericaceae) among plants, indicators of the Mediterranean proper psyllid fauna are the tribe Arytainini (Psyllidae) and some genera of Aphalaridae (Euphyllura Foerster, Strophingia Enderl., etc). • Approximately 100 species of Eumediterranean psyllids are known today. Of 212 species of the Caucasian psyllids, only one, Livilla cognata Aulm. (host plant: Chamaecytisus caucasica), penetrated fom Asia Minor to South-Eastern Georgia. This date is the perfect example of the infiltration of Eumediterranean psyllid fauna onto the Caucasus region (Gegechkori, 1984, 1985, 2004). • On the basis of comparative analysis of the psyllid fauna of the Apennine, Iberian (Pyreness) and Bsalkan peninsulas and Asia Minor, historical reasons of the infiltration of the Mediterranean proper fauna onto Caucasus are investigated. The main reason of infiltration of the psyllid fauna closely connected with the representatives of the maquis community is explained by the deterioration of the Mediterranean proper (summer-dry) climate in the Caucasus. This analysis allowed the author to make a correct zoogeographical regionalization of the Caucasus. This region belong to the Euro-Siberian and Irano-Turanian regions of the Palearctic realm. • With respect to investigations carried out by D.M.Percy (2001,2003) the Eumediterranean fauna of Canary and Azores islands enriched by many species which considerably changed the spectrum of Mediterranean psyllid fauna in general. Therefore, our point of view regarding to the center of origination of Eumediterranean fauna of psyllids and its impoverishment within to the marginal regions of above mentioned center is quite correct • In the Cretacious (136-65 mya) according to the brake up of the Laurasia, North America split away from the Europe, hence, the Mediterranean proper fauna of psyllids occurred in New World in California chapparal. In the other side of the Atlantic Ocean previously mentioned fauna had the secondary far more successful center of origination, giving a new taxon - Neophyllura Log. Species of this genus are closely connected by feeding habits with the Arbutus, Arctostaphylos. Mentioned paleogeographical reconstructions, as we see, triggered the vicariance events between psyllid fauna of the two former Laurasian continents.