Species delimitation in the crypsis‐defended and polymorphic stick insects of the genus Libethra (Phasmatodea, Diapheromeridae)

Abstract

Crypsis is a widespread defensive mechanism for prey ambushed by visually oriented predators. One well‐documented consequence of this interaction is the formation of search images by the predator that leads to the coexistence of multiple morphs in the prey population. Libethra is a genus of stick insects whose ornamentation and coloration are decidedly protective and exhibit exuberant intraspecific variation. Despite this fact, these traits have been extensively used to support the boundaries between the species it includes. This is the case in the north Andean species Libethra rabdota and Libethra rabdotula, delimited on the basis of a specific arrangement of ornamental characters. To state whether such taxonomical practice is meaningful and convenient, we evaluated the grouping of specimens of both species by means of the independent inference of phylogenies obtained with mitochondrial DNA sequences and ootaxonomy. This article synonymizes L. rabdota and L. rabdotula, redescribes the adults and describes the egg of the species. Additionally, we demonstrate that the characters related to crypsis used for the diagnosis of L. rabdota are not exclusive to this species by describing Libethra rioblanco sp. n. and Libethra ucumariensis sp. n. Our findings suggest that this genus requires extensive revision, but also provide support for the usage of different tools that might produce more accurate and stable classification. Evolutionary scenarios for both the extreme morphological variation and possible homoplastic state of camouflage‐related traits are discussed herein.