Integrative taxonomy increases biodiversity knowledge of Gusana (Platyhelminthes, Tricladida, Geoplanidae) with the description of four new Chilean species

The Chilean land planarian genus Gusana (Platyhelminthes, Tricladida, Geoplaninae) currently comprises three species that were described in the 19th century. Four new species of the genus are described herein, namely G. hualpensis Carbayo, sp. nov., G. lujanae Almeida & Carbayo, sp. nov., G. melipeucensis Almeida & Carbayo, sp. nov. and G. purensis Bolonhezi, Almeida & Carbayo, sp. nov. An integrative taxonomy approach was adopted by combining morphological (anatomy, histology) and molecular (COI and 28S genes) information. Additionally, the monophyletic status of Gusana is investigated and the species are delimited by a recently introduced molecular delimitation method based on pairwise genetic distances. All Gusana species are very similar in attributes such as body shape, dorsal colour pattern and internal organs, namely the pharynx and copulatory apparatus and only differ in the details. Gusana is retrieved as monophyletic and the molecular delimitation method recovered the same species recognised morphologically. A rediagnosis of the genus and replacement of G. lota into Pseudogeoplana are also proposed. A new role of the penis papilla is also suggested based on the spermatophore found in Gusana lujanae.