Prey capture and feeding behaviour in an endemic land flatworm from São Tomé Island

ABSTRACT

Two specimens of the endemic land flatworm species Othelosoma impensum Sluys & Neumann, 2017 from the volcanic island São Tomé were observed in the wild in Obo-National Park while they were preying on ants that had descended on a tree trunk after their nuptial flight. A maximum of 41 ants were assembled in a cluster by one of the flatworms, the insects being immobilised by mucus secreted by the worms. A strong cephalic retractor muscle facilitated capture of the mobile prey. Presence or absence of similar cephalic adaptations in other species of Othelosoma and other genera of land flatworms is discussed, as well as the effectiveness of the sticky mucus secreted by the worms during prey capture.

KEYWORDS:

• Ants
• cephalic adaptations
• mucus
• Othelosoma
• prey capture
• retractor muscle

Acknowledgements

We are grateful to the General-Director of the Environment of São Tomé and Príncipe, Mr. Arlindo Carvalho, for granting permission for fieldwork by MT on both São Tomé and Príncipe during March-May 2016. MT gratefully acknowledges financial support from Naturalis Biodiversity Center, Leiden, The Netherlands (in the form of two Martin Fellowships), the Rudolf und Ursula Lieberum Stiftung, Kassel, Germany, and the California Academy of Sciences, San Francisco, USA.

Drs R. C. Drewes (Department of Herpetology, California Academy of Sciences, San Francisco, USA) and R. F. de Lima (Centre for Ecology, Evolution and Environmental Changes, Lisbon University, Portugal; Associação Monte Pico, Monte Café, São Tomé and Príncipe) are thanked for facilitating fieldwork of MT on São Tomé and Príncipe. Prof. C. van Achterberg (Naturalis Biodiversity Center) kindly examined preserved specimens of the ants. We are very grateful to Senior Research Technician Roland Butôt (Naturalis Biodiversity Center) for generating the molecular sequences and for performing the BLAST searches. Drs L. Winsor (James Cook University, Townsville) and J-L. Justine (Museum National d’Histoire Naturelle, Paris) are thanked for information on land flatworms preying on insects. Prof. Dr.-Ing. Heralt Schöne (Hochschule Neubrandenburg, Germany) is thanked for reading an earlier draft of the manuscript. We are grateful for the helpful comments made by two anonymous reviewers.

Disclosure statement

The authors declare no conflicts of interests.