Taxonomic revision of the Mexican Eucyclops (Copepoda: Cyclopoida) with comments on the biogeography of the genus

ABSTRACT

Based on the examination of specimens deposited in different national and international biological collections, we reviewed the ca. 800 records of the genus Eucyclops in Mexico and compared them with the type material of presumedly widespread species. Resulting from our taxonomical analysis, in this contribution we recognise 17 species dwelling in Mexico. Complementary upgraded descriptions of eight species emphasising newly introduced taxonomic characters are also presented from the examination of Mexican specimens. These species include E. elegans, E. prionophorus, E. festivus, E. leptacanthus, E. torresphilipi, E. chihuahuensis, E. cuatrocienegas and the recently described E. tziscao and E. angeli. In addition, the use of upgraded descriptive standards involving new morphological characters allowed the discovery of six new species that are described in this work: E. alekseevi sp. nov., E. wixarica sp. nov., E. defayeae sp. nov., E. mittmanni sp. nov., E. estherae sp. nov. and E. ishidai sp. nov. Most of these species were previously recorded in Mexico under different names. The occurrence of E. pectinifer, E. elegans, E. prionophorus and E. leptacanthus in Mexico is herein confirmed. We propose the ornamentation patterns of the fourth swimming legs (i.e. basipodite, coxal plates) as reliable additional characters to recognise closely related species of Eucyclops. The importance of the antennal basis ornamentation in the taxonomy of the genus is supported by our data. We evaluated the taxonomic value of 113 morphometric and binary characters using statistical methods; results of this analysis showed that morphometric characters alone overlap and thus have a limited value to distinguish species of Eucyclops. We include comments on E. serrulatus s. str. in order to provide a complete comparison frame among members of the serrulatus-species complex, but we did not find the strict form in the samples examined. A key to the Mexican species of the genus is also provided.

KEYWORDS:

• serrulatus-complex
• freshwater copepods
• taxonomy
• diversity
• morphometrics

Acknowledgements

This work is part of the first author’s (NFM-S) doctoral thesis, developed at El Colegio de la Frontera Sur (ECOSUR). This contribution was supported by CONACyT project 133404-Investigación Científica Básica 2009. The support and comments of members of the thesis committee, Drs. Martha A. Gutiérrez-Aguirre, and David González-Solís are deeply appreciated by the authors of this work. We gratefully acknowledge the support of Araceli Adabache, Laboratorio de Ecología, Universidad de Aguascalientes, for help and advice in the SEM processing and examination of the specimens. Also, we thank MSc Laura Fernández-Pérez for her kind help in the statistical analysis of the numerical data presented. Cuahutemoc Ruíz Pineda helped in polishing the final edition of the SEM photographs. We gratefully acknowledge the key support of Dr. Hans-Walter Mittmann (Staatliches Museum für Naturkunde, Karlsruhe), Dr. Danielle Defaye (Muséum National d´Histoire Naturelle, Paris), Drs Frank D. Ferrari and Chad Walter (National Museum of Natural History Smithsonian Institution, Washington, DC), Victor Alekseev (Russian Academy of Sciences) and Rosa María Hernández (El Colegio de la Frontera Sur, Chetumal) for loaning the material examined in this work. We also acknowledge the help, time and patience of Jörg Pertzel and Gerald Islebe in translating the original descriptions of species from German to English.