Seasonality and prevalence of the fungal trichomycete Asellaria jatibonicua in the terrestrial isopod Litthorophiloscia culebrae

Abstract

Los tricomicetos son microorganismos que viven mayormente en el intestino de artrópodos con mandíbula. Son considerados como un grupo ecológico compuesto de hongos (Asellariales y Harpellares) y protistas (Amoebidiales y Eccrinales). Para entender el comportamiento de estos simbiontes es necesario entender primero la biología de su hospedero, por lo cual comparamos la prevalencia de Asellaria jatibonicua en el intestino del isópodo terrestre Litthorophiloscia culebrae con diferentes parámetros ambientales tales como: porciento de humedad relativa, temperatura y precipitación de lluvia. Los isópodos fueron colectados semanalmente en la Universidad de Puerto Rico, Recinto de Mayagüez por un periodo de 18 meses. Se determinó una prevalencia promedio de A. jatibonicua de 26% con mayor prevalencia en los meses de mayor humedad relativa. Además, encontramos una nueva especie para Puerto Rico en el mismo hospedero, Parataeniella sp. (Ichthyosporea: Eccrinales), la cual describimos completamente.

The trichomycetes is a group of commensal microorganisms generally found in association with the digestive tract of mandibulated arthropods. They have been recognized as an ecological group composed of Kickxellomycotan fungi (Asellariales and Harpellales) and Ichthyosporean protists (Amoebidiales and Eccrinales). Isopods, in particular, harbor fungal members belonging to the Asellariales (rarely Harpellales). One essential aspect of the ecology of the Asellariales is to understand the environmental conditions that regulate isopod populations. For instance, the different environmental fluctuations of temperature, water precipitation and relative humidity affect isopod lifestyle and, thus potentially, the life cycle of these fungi. In this study, isopods were collected in the University of Puerto Rico - Mayagüez and dissected in the laboratory the same day, in order to verify the presence of Asellaria jatibonicua. We determined an average prevalence of 26% over 18 months and observed seasonality behavior of Asellaria jatibonicua associated with the terrestrial isopod Litthorophiloscia culebrae Moore, 1901. Data show a low prevalence of the fungus in the less humid months (with the lowest prevalence of 7% in August 2012 and 8% in March 2013), increasing towards the more humid months (with the highest prevalence of 44% in September 2012 and 55% in December 2012). In addition, during this study we found another trichomycete in the same host, Parataeniella sp. (Ichthyosporea: Eccrinales), which is described in this script and represents a first record for Puerto Rico and a new species for science.