First record and range extension of Metachromadora (Metachromadora) chandleri (Chitwood, 1952) Timm, 1961 (Nematoda: Desmodoridae) from the Pacific coast of Costa Rica, with comments on its taxonomical status

Introduction: Costa Rican marine nematofauna has been poorly studied despite it is one of the most abundant and numerous group in sediment samples. Objective: To report the first finding of Metachromadora chandleri from Costa Rica, on the Pacific coast. Methods: Fresh samples of several marine substrates from the North Pacific Costa Rican coasts were analyzed to extract the nematodes; they were identified to genus level. Key features were photographed, phylogenetic analyses were done with the obtained sequences. Results: Four individuals from two locations matched the description of M. chandleri; we obtained the first three COI sequences of this species. Discussion: This is the first report of this species in Costa Rica and the second for the Pacific, but it is more widespread in the Atlantic. Some comments on the taxonomical status, molecular knowledge on the genus and distribution of the species are given. Conclusion: Metachromadora chandleri is present on both coasts of the American continent with most reports from the Atlantic; the species are scarcely represented in molecular databases. This first record of M. chandleri in Costa Rica reinforces the need of further local studies to reveal the diversity of marine taxa and enrich our understanding of the global distribution of species.