Geographical variation in mandible morphologies specialised for collembolan predation depend on prey size in the ant Strumigenys lewisi

1. Ants in the genus Strumigenys are predator ants that feed on tiny soil arthropods. The mandibles are modified into high‐speed traps to capture swift collembolan prey. The peculiar mandible morphologies of these ants have evolved depending on characteristics of the prey. Specifically, the evolution of mandible size and shape may be directly driven by prey size. 2. In the present study, the intraspecific variation of the morphological traits of Strumigenys lewisi populations were observed in central Japan. The relationships between the morphological variations and the prey body size were analysed. 3. In workers and queens, three morphological traits, head width, mandible length, and mandible width were significantly different among the multiple sites. Specifically, the mandible length was shorter in southwestern Japan than in other sampling locations. The ancova model revealed that the allometry of the mandible length to the head width was different among the sites. 4. As predicted, the mandible length was positively correlated with the average body size of collembolans in the Entomobryidae family. Furthermore, multiple regression analysis showed that the variation of the mandible length was affected by environmental factors represented as location information. However, the effect of collembolan body size was more effective at predicting mandible length. The study suggests that the geographical variation of mandible morphologies in S. lewisi has been selected by predator–prey interactions with collembolans.     

中国大陆瘤颚蚁属分类研究(膜翅目,蚁科)

记述中国大陆瘤颚蚁属Strumigenys 8种,其中1新种,江西瘤颚蚁S．jiangxiensis sp．nov．,粗瘤颚蚁S．stry—gax Bolton为中国新纪录种。提出《广西蚂蚁》和《西双版纳自然保护区蚁科昆虫生物多样性研究》中记载的4个误订种,即刘氏瘤颚蚁S．lewisi Cameron误订为粗糙瘤颚蚁S．hispida Lin et Wu,薄帘瘤颚蚁S．rallarhina Bolton误订为异形瘤颚蚁S．leptorhina Bolton,粗瘤颚蚁S．strygax Bolton误定为琴状瘤颚蚁S．1yroessa(Roger),长瘤颚蚁S．exilirhi-na误定为费氏瘤颚蚁S．feae Emery。编制了中国大陆瘤颚蚁属已知种工蚁的分类检索表。