Cladomorphus petropolisensis, a New Species of Stick Insect from the Atlantic Forest, Rio de Janeiro, Brazil

Simple Summary The order Phasmatodea includes the longest Brazilian insects, known by their remarkable morphological and behavioural adaptations for camouflage such as sticks, moss, and leaves; they are predominantly nocturnal and phytophagous insects. Cladomorphus phyllinus Gray, 1835 is one of the most common and best-known stick insect species in Brazil. It feeds mainly on guava leaves, angico, and powder-puff, and reproduces sexually and asexually. Cladomorphus phyllinus presents marked sexual dimorphism in the adult: winged males are significantly smaller in size than females and can reach up to 13 cm, while females can reach 23 cm in length and are apterous. A female specimen collected in the Atlantic Forest in Petropolis, Rio de Janeiro, Brazil, was compared with a C. phyllinus specimen, identified according to published literature. The differences between the two specimens related to the general size and several morphological characters were observed. In order to add evidence that the recently collected specimen belonged to a species distinct from C. phyllinus, part of the cytochrome oxidase I (COI) gene was sequenced and analysed. The comparative analysis of the COI sequences from the two specimens revealed significant differences that, together with the morphological characters and recorded sympatry of the two specimens, support the existence of a new species, which is described here as Cladomorphus petropolisensis. Cladomorphus petropolisensis sp. nov., a new species of stick insect from Petropolis, Rio de Janeiro, Brazil, is herein described and compared to the other sympatric species, C. phyllinus Gray, 1835 (Phasmatidae, Cladomorphinae). The description of the new species is supported by morphological and molecular evidence. Kimura-2-parameter (K2P) intraspecific COI divergences among the holotype of C. petropolisensis sp. nov. and C. phyllinus individuals ranged from 2.9% to 4.4%, which are suggestive of distinct species, especially when considering that all Cladomorphus individuals studied were collected in the Petropolis municipality. The new species can be distinguished from C. phyllinus Gray, 1835 by several characteristics: smaller size, the presence of two spines on the hind femora, the relative longer length of the ovipositor, and spiny tegument, especially in the mesonotum, sculpturing of the operculum of the egg.