A review of Chorthippus species with angled pronotal lateral keels from Greece with special reference to transitional populations between some Peloponnesean taxa (Orthoptera, Acrididae)

This paper presents a summary of the current knowledge on the systematics of the Greek taxa of Chorthippus, morphologically characterised by angled lateral pronotal keels (usually grouped as Glyptobothrus). Prior to this paper, based on traditional morphology, ten taxa of Chorthippus with angled lateral pronotal keels were recognized from Greece. Based on morphology as well as (and more importantly so) bioacoustics thirteen Greek taxa are now recognised. With addition of a few additional related taxa that occur only outside Greece, all are treated in this paper: Chorthippus apricarius apricarius (Linnaeus, 1758), C. vagans vagans (Eversmann, 1848) (not in Greece), C. v. cypriotus (Uvarov, 1936) stat. nov. [Cyprus], C. v. africanus Nadig, 1981 [N. Africa], C. v. dissimilis subspec. nov., C. willemsei Harz, 1971, C. biroi (Kuthy, 1907), C. sangiorgii (Finot, 1902), C. bornhalmi Harz, 1971, C. biguttulus euhedickei von Helversen, 1989, C. biguttulus parnassicus subspec. nov., C. moreanus spec. nov., C. mollis mollis (Charpentier, 1825), C. mollis pechevi Karaman, 1975 [Bulgaria], C. mollis lesinensis (Krauss, 1888) stat. nov. [Dalmatia], C. crassiceps (Ramme, 1927), C. parnon spec. nov. and C. pulloides (Ramme, 1927). A key to the Greek taxa is presented and for each taxon data on morphology, bioacoustics, ecology, differential diagnosis and distribution are provided. Using bioacoustics and morphology most populations in Greece can be easily and reliably identified. However in the Peloponnese, populations occurring in the contact zones of the disjunct distribution areas of C. pulloides, C. crassiceps, C. parnon and C. moreanus show intermediate morphological and bioacoustical characteristics. Identification of these transitional populations is cumbersome, arbitrary and commonly impossible. In recent research such populations have been treated as hybrid populations occurring in hybrid zones between naturally hybridizing species. The situation in the Peloponnese requires further research (e.g. behavioural and molecular analysis), to disentangle the degree of speciation, to assess species delimitations, their taxonomic status, palaeobiogeography, evolution and the phylogeny within this group.