Host‐race formation in Chaetostomella cylindrica (Diptera: Tephritidae): Morphological and morphometric evidence

Present address: Mohammad S. Al‐Zein, Old Dominion University, Norfolk, VA, USA.

Abstract

Chaetostomella cylindrica is a highly oligophagous tephritid infesting the flower heads of six genera and 10 species of thistles in Lebanon, and is predominant on two hosts in sympatry, Notobasis syriaca and Onopordum illyricum. Adult flies emerging from N. syriaca fit more closely the description of the species with respect to the colour and pattern on the mesonotum. This study compares morphometrically and morphologically the host races associated with N. syriaca and O. illyricum. Immatures of both races were similar, but all stages of the Onopordum‐associated race were significantly larger. Morphometric studies, based on two head and five wing measurements, using canonical discriminant analysis, allowed for the differentiation of the host races with more than 70% accuracy. The aculeus shape and length differed significantly between females of both races. The holotype of Trypeta lurida Loew 1844 was examined and appeared closer to the Onopordum host race. Chaetostomella cylindrica appears to be a complex of cryptic and reproductively isolated species.

Present address: Mohammad S. Al‐Zein, Old Dominion University, Norfolk, VA, USA.

Keywords:

• Chaetostomella cylindrica
• fruit flies
• host races
• Lebanon
• Tephritidae
• thistles

Acknowledgements

The authors would like to thank Dr J. Ziegler (ZMHU) for arranging loan of the C. lurida holotype, Dr V. Korneyev (Royal Museum for Central Africa, Belgium) for his useful feedback on the manuscript, and Miss H. Zournajian for her help in rearing and processing insects. This study was funded by the American University of Beirut, University Research Board.

Notes

Present address: Mohammad S. Al‐Zein, Old Dominion University, Norfolk, VA, USA.