Historical biogeography of Temnocephalida (Platyhelminthes, Rhabdocoela): testing the Gondwanan hypothesis

Abstract

Temnocephalida, a group of small epibiontic worms strictly associated with freshwater hosts, includes 179 taxa in 23 genera, classified in two major groups: Scutarielloidea, distributed in the Palaearctic region, and Temnocephaloidea distributed mainly in the Australian and Neotropical regions. Based on a large-scale spatio-temporal dimension, a biogeographic hypothesis on a Gondwanan scenario was tested. The objective of this study was to describe the geographic distribution patterns of Temnocephalida in a primary biogeographic homology context. A dataset of 793 temnocephalan records, distributed in 45 hydrological basins, and assigned to different hierarchical taxonomic levels was used to construct five presence/absence matrices. We analysed the matrices using Parsimony Analysis of Endemicity (PAE) and Cladistic Analysis of Distributions and Endemism (CADE). Furthermore, we constructed generalized tracks based on area clades with phylogenetic support, i.e., two or more synapomorphies. Six generalized tracks were revealed: a general clade for Eurasia, plus a complex of four hybrid zones with monophyletic relationships included in a major clade with Gondwanan affinities. The results represent the first study using biogeographic analysis to disentangle the distributional patterns of temnocephalids around the world. Based on the integration of the results obtained by biogeographic pattern-based methods, we infer that the fragmentation of Gondwana affected the diversification patterns and distribution of Temnocephalida.

Key words:

• CADE
• diversity
• endemism
• freshwater river basin
• PAE
• Pangea
• symbionts
• tracks analysis

Acknowledgements

We thank V. León-Regagnon, C. Mathuriau, S.M. Martínez Zam, R. Pérez-Rodríguez, C. Rodríguez, S.M. Martorelli, L. Negrete, for support during fieldwork. L. García-Prieto and C.A. Mendoza-Palmero for providing literature and specimens for morphological comparison deposited at the CNHE. Thanks are also due to Dr Fadia Sara Ceccarelli, Dr J.J. Morrone, and an anonymous reviewer for helpful comments and critical revision of the manuscript. This study is the result of a research internship as part of the Bachelor's degree programme of J.V.-R. under the leadership of A.M-A. A.M.-A. thanks Fernando Carbayo for his invitation to present a lecture during the Ibero-American Symposium on Platyhelminth Biology (in Portuguese) at CBZ XXXI (Cuiabá, Brazil, March 2016). This work was supported by a postdoctoral grant from CONACyT, Mexico (No. 238789) to A. M.-A., and his research is supported by the grant No. 201441 financed by the Sectorial Hidrocarbon Fund CONACyT-SENER to the CIGoM Consortium.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplemental data

Supplemental data for this article can be accessed here: http://dx.doi.org/10.1080/14772000.2016.1252441.

Additional information

Funding

This work was supported by the Consejo Nacional de Ciencia y Tecnología [grant number 201441,238789]; Consejo Nacional de Investigaciones Científicas y Técnicas [grant number PIP-0390,PIP-11220120100635CO]; Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata [grant number N11/728]