Poecilimon Fischer (Orthoptera, Tettigoniidae) consists of about 130 species and a functional taxonomy of the genus requires arranging species into phylogenetic groups. However, this is a task that requires detailed empirical testing. This paper documents data on Poecilimon species with an inflated pronotum. The Poecilimon (Poecilimon) inflatus group is a lineage ranging along a narrow zone in the south-west corner of Anatolia and in Crete plus some other Aegean islands. By producing data of morphology and calling songs of males and responding songs of females the composition and intra-group diversity of P. inflatus group are studied. Both morphology and male calling and female responding songs, exhibited a considerable intra-group diversity. In the light of data obtained the following nomenclatural changes were made. The genus Parapoecilimon Karabağ, 1975 syn. n. is synonymised with Poecilimon Fischer and Parapoecilimon antalyaensis Karabağ, 1975 is given a new combination, Poecilimon antalyaensis (Karabağ, 1975) comb. n. Four new taxa are described in the group: (i) Poecilimon isopterus sp.n.; (ii) Poecilimon inflatus lyciae subsp. n.; (iii) Poecilimon antalyaensis myrae subsp. n., and (iv) Poecilimon antalyaensis anemurium subsp. n. The Poecilimon (P.) inflatus species group consists of the following species: (i) Poecilimon inflatus Brunner von Wattenwyl, 1891; (ii) Poecilimon martinae Heller, 2004; (iii) Poecilimon cretensis Werner, 1903; (iv) Poecilimon antalyaensis (Karabağ, 1975) comb. n.; (v) Poecilimon bilgeri Karabağ, 1953 and (vi) Poecilimon isopterus sp.n. The species group is defined by a combination of characters including the pronotum inflated in metazona and a male cerci mostly black in their apical 1/2-1/3. The male calling song has typically two types of short syllables and the females respond acoustically with very short latency times. By using combination of morphology and song data we suggest three main lineages in the group: (i) P. bilgeri, (ii) P. antalyaensis and (iii) the other four species.