Beetles (Coleoptera) of Peru: A Survey of the Families. Chrysomelidae: Cassidinae Gyllenhalsensu lato

Abstract

Diversity in Peru: 18 tribes, 49 genera, 620 species. Recognition: Cassidinae is a distinct branch within Chrysomelidae, with 36 tribes and ,6000 species recognized worldwide. Cassidines were formerly recognized as two subfamilies, which is still reflected in the two online catalogs on classical leafmining leaf beetles (Hispinae; Staines, 2012) and tortoise beetles (Cassidinae; Borowiec and Świetojanska, 2014). These catalogs overlap in their coverage of Imatidiini and Spilophorini, reflecting the lack of clarity about monophyly and relationships at the tribal level within Cassidinae. The subfamily Cassidinae encompasses a wide diversity of morphology and behavior (Chaboo, 2007). However, all cassidines share fundamental diagnostic traits—the head is opisthognathous with the vertex projecting forward and the mouth directed ventrad; the tarsomeres are not pseudotetramerous (as in other leaf beetles) but the 4th tarsus has become lost so the tarsal formula is 4-4-4; and the abdomen has ventrites 1–2 connate with the suture indicated as a groove. Across Cassidinae, the adults of basal taxa are elongate and linear and have the head exposed (the hispine forms) while adults of the derived taxa (tortoise beetles) are more rounded and have the pronotal and elytral margins expanded, with the pronotal margin usually covering the head in dorsal view, leaving only the antennae exposed. The eggs, larvae and pupae also show diverse biology and morphology within the subfamily; all stages occur on the same host plants as adults. Leaf-mining larvae are poorly documented, requiring close examination of leaves for blotch and linear mines. Habitat: Cassidines are herbivorous, and spend the entire life cycle on their host plants. Host records are documented for the majority of genera, indicating that species can be highly restricted to one or a few genera and certain families. A few species show more labile host choices. Given the tendency to specialize on certain families, it is most efficient to collect cassidines by targeted beating with sheet on such plants. General beating will help to discover new host plant records. Certain tribes are fairly restricted to Zingiberales (Arescini and Cephaloleiini; Staines, 2004, 2012; Jalinsky et al., 2014), palms (e.g., Hemisphaerotini; Mariau, 2004; Alurnini Staines, 2012), Bignoniaceae (e.g., Dorynotini), and bamboo or bambusiform grasses (e.g., see Staines, 2012). Tortoise beetles tend to be sun-lovers and are generally found in more open, disturbed habitats (e.g., road-cut vegetation, trails, tree-fall gaps); it is unclear if they occur in the canopy of intact forests. Cassidine juveniles may be solitary or gregarious, cryptic or exposed, and may be guarded by mothers in highly