Isopods and ants: Novel ant associations and new records from Puerto Rico

Terrestrial isopods are a diverse and widespread group of malacostracan crustaceans frequently observed as facultative and obligate associates of ants. For most myrmecophilous isopods, the exact association with ants remains unclear, as records frequently lack behavioral data or habitat descriptions. We report the first records of Trichorhina heterophthalma Lemos de Castro, 1964 and Caraiboscia christiani Leistikow, 2001 from Puerto Rico and the first documented ant associations in both taxa. Isopods were found in nests and surrounding substrates of five co-occurring ant species from four subfamilies (Ponerinae, Formicinae, Ectatomminae, Myrmicinae) in the Luquillo Experimental Forest, Puerto Rico. We also present brief observations of T. heterophthalma interactions with Holcoponera striatula Mayr 1884 workers. The broad host ranges of myrmecophilous isopods highlight the need for better taxonomic resolution and more field observations in the group. Horizontal surveys of ant associates within sympatric ant communities may be useful in countering methodological biases which have guided our understanding of ant associations as a general eco-evolutionary phenomenon.