Plagiometriona emarcida (Boheman, 1855) and Plagiometriona forcipata (Boheman, 1855) (Coleoptera: Chrysomelidae: Cassidinae), a single species differing in larval performance and adult phenotype

Abstract

Matings frequently observed between the tortoise beetles <I>Plagiometriona forcipata</I> (Boheman, 1855) and <I>Plagiometriona emarcida</I> (Boheman, 1855), in the State of Rio de Janeiro, Brazil, led us to compare the ecology, life history and genetics of these two morphologically distinct species. Host plant censuses revealed <I>P. emarcida</I> was about five times more abundant, while populations of both species responded in parallel to climate. Laboratory-reared immature <I>P. forcipata</I> took 2 days longer to complete development and showed higher mortality rates. No differences were detected in ovipositional behaviour, genitalia morphology or in sex ratio of offspring. The adult offspring of field-caught females of both species contained individuals with both species&#39; elytral patterns. Finally, nearly identical cytochrome oxidase I sequences obtained from individuals of each species suggest that they are a single polymorphic species. Based on these observations and the examination of type material we propose the new synonymy: <I>Plagiometriona forcipata</I> = <I>P. emarcida</I>, <B>syn. nov.</B>