Researchers finds a new species of stick insect in the state of Rio de Janeiro

Researchers of the Laboratory of Entomology Diversity of the Oswaldo Cruz Institute (IOC/Fiocruz) identified a new species of stick insect in Petrópolis, in the mountainous region of the state of Rio de Janeiro. It has been named Cladomorphus petropolisensis, after the city where it was collected. The finding was published in the 10-year anniversary issue of Animals. The last species of genus Cladomorphus in the region was described in 1835 by scientist George Robert Gray.

A specimen of ‘Cladomorphus petropolisensis’ was deposited in the Entomological Collection of the IOC/Fiocruz (photo: Reproduction)

“We are incredibly happy to be helping increase knowledge on Brazilian biodiversity with the discovery of a species that belongs to a group that has not been very studied so far. Stick insects have very interesting characteristics, such as camouflage and asexual reproduction”, said Jane Costa, first author of the article and substitute head of the Laboratory of Entomology Biodiversity of IOC/Fiocruz.

Based on the morphological analysis, the authors observed that the physical characteristics of C. petropolisensis were significantly different, in terms of length and the arrangement of spikes, from those of another similar species that live in the same area, Cladomorphus phyllinus. “Although they are physically very similar, the difference in size is their most noticeable feature. The new species is almost 5 cm longer. It also has more spikes on part of its thorax and hind legs”, said Costa.

Another characteristic that differs between the two species is the eggs laid by the females: while those laid by C. phyllinus are a uniform brown, those of C. petropolisensis have a more irregular color pattern, in brown and beige hues. The evidence observed via morphological evaluations was then proven through genetic sequencing, confirming that the specimen belonged to a species that had never been recorded in scientific literature.

“This type of analysis comes with a very relevant level of precision. By combining morphological and molecular investigations, we were able to outline with more certainty the characteristics of each species”, Costa, a biologist, explained.

The other scientists who were involved in the discovery were Jacenir Mallet, of the Interdisciplinary Laboratory of Diptera and Hemiptera Entomology Surveillance of the IOC/Fiocruz, and Daniela Maeda Takiya, of the Entomology Laboratory of the Biology Institute of the Federal University of Rio de Janeiro (UFRJ).

The specimen used to describe C. petropolisensis was found in an area of the Atlantic Rainforest in May 2022. It is currently preserved and deposited at the Entomology Collection of the IOC (CEIOC/Fiocruz), home to more than 5 million insects and considered one of the most precious collections of Latin America. The Laboratory has recently published the children’s book Eu, o bicho-pau (I, the stick insect), which promotes the study of biodiversity and respect for the various creatures of nature by telling the story of a child who finds a mysterious insect shaped like a stick, the stick insect.