The influence of developmental days on body size and allometry of head width in male Loxoblemmus angulatus (Orthoptera: Gryllidae)

Male crickets belonging to the genus Loxoblemmus Saussure (Orthoptera: Gryllidae) often exhibit exaggerated facial structures with characteristic projections. Whether these structures are stable within a single species is not certified. We collected Loxoblemmus angulatus Bey-Bienko and reared the second generation under 16:8, 14:10, and 12:12 light:dark photoperiods. Body morphology of adults was measured and development days were recorded. The results showed that short daytime photoperiod made them develop slowly. Males became larger after longer developmental days. Head width was wider in males and horns on head were more exaggerated in large individuals than in small ones. Head width was allometric against pronotum width. Our study shows that the male head morphology in L. angulatus is strongly influenced by development days and it is not suitable as taxonomic characters.