Deep-sea shrimp of the family Sergestidae Dana, 1852 provide a unique system for studying the evolution of bioluminescence. Most species within the family possess autogenic bioluminescent photophores in one of three distinct forms: lensed photophores; non-lensed photophores; or internal organs of Pesta. This morphological diversity across the Sergestidae has resulted in recent major taxonomic revisions, dividing the two major genera (Sergia Stimpson, 1860 and Sergestes Milne Edwards, 1830) into 15. The present study capitalises on molecular data to construct an updated genus-level phylogeny of sergestid shrimp. DNA was successfully extracted from ~87 individuals belonging to 13 of the 15 newly proposed genera. A ‘genome skimming’ approach was implemented, allowing the capture of mitochondrial genomic data across 19 sergestid species. Additional individuals have been incorporated into the phylogeny through Sanger sequencing of both nuclear (H3 and NAK) and mitochondrial (16S and COI) genes. The resulting molecular phylogeny is compared with previous morphological trees with specific attention to genus-level relationships. The -sergestes group was rendered non-monophyletic and the -sergia group was recovered as monophyletic. Ancestral state reconstructions of light organ type indicate that organs of Pesta is the ancestral state for the family. Non-lensed photophores evolved once across the -sergia group, but were later lost in the deepest living genus, Sergia. Lensed photophores also evolved once within the genera Prehensilosergia Vereshchaka, Olesen & Lunina, 2014, Lucensosergia Vereshchaka, Olesen & Lunina, 2014 and Challengerosergia Vereshchaka, Olesen & Lunina, 2014. These findings identify preliminary patterns across light organ type and species’ depth distributions; however, future research that incorporates finer-scale depth data and more species is needed to confirm our findings.

Resumen Cyclopes didactylus es la especie más pequeña y menos estudiada entre los osos hormigueros. Existe poca información sobre su distribución en México, encontrándose sólo registros esporádicos en los estados de Chiapas, Oaxaca, Veracruz y Tabasco. En los años 2010, 2013, 2016 y 2017 registramos la presencia de cinco individuos de C. didactylus en Tabasco: una hembra en el municipio de Centla, un macho en el municipio de Macuspana y tres ejemplares en el municipio de Tacotalpa, dos de ellos de sexo desconocido. Los presentes registros son los más actuales para México, contribuyendo así al conocimiento de la especie. Palabras clave: área natural protegida, manglar, reserva de la biosfera, selva mediana perennifolia New records of Cyclopes didactylus (Pilosa: Cyclopedidae) in Tabasco, Mexico Abstract Cyclopes didactylus is the smallest and least known species among the anteaters. There is limited information about its distribution in Mexico, with only scarce records from the state of Chiapas, Oaxaca, Veracruz, and Tabasco. In the years 2010, 2013, 2016, and 2017, we documented the presence of five individuals of C. didactylus in Tabasco: one female in Centla municipality, one male in Macuspana municipality, and three individuals in Tacotalpa municipality, two of them of unknown sex. These records represent the most recent sightings for Mexico, contributing to the knowledge of the species.