Collastoma anderseni sp. nov. (Rhabdocoela: Umagillidae: Collastominae), an endosymbiont from the intestine of the sipunculan Themiste lageniformis

ABSTRACT

A new endosymbiont platyhelminth, Collastoma anderseni sp. nov., is described from the gut of the sipunculan, Themiste lageniformis. Host T. lageniformis were collected for study in January and February of 2016 from Hawai’i Kai, O’ahu. Umagillids have not previously been reported inhabiting T. lageniformis; however, umagillids belonging to the genus Collastoma are known exclusively as endosymbionts of sipunculans. Two other species of Themiste, T. pyroides and T. dyscrita, are also known as hosts to Collastoma spp. Collastoma were found in 19 (90.5%) of the 21 sipunculans collected. The average number of flatworms within all sipunculans collected was 7.05 (± 5.72). The number of flatworms per infested individual ranged from 1 to 21. A full description of the species is given and the relationships of the seven known species of Collastoma are discussed.

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KEYWORDS:

• Sipuncula
• Hawaii
• Umagillidae
• Collastoma
• endosymbiont

Acknowledgements

Thanks to Dr Wagner Magalhães for all his help with guiding and preparing this work. Thanks to Dr Greta Aeby for her assistance in identifying and locating the stains needed to prepare and describe this species. Thanks to Dr Thierry Work for providing the staining agents used in this work.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Water Resources Research Corporation.