Revising Mariametridae: the genera Dichrometra, Lamprometra, and Liparometra (Echinodermata: Crinoidea)

Abstract

The featherstar genera, Dichrometra A.H. Clark, 1909a, Lamprometra A.H. Clark, 1913, and Liparometra A.H. Clark, 1913 (Comatulida: Mariametridae), are currently diagnosed only on the basis of the relative lengths of their proximal three pairs of pinnules. Previous published descriptions and a morphological re-examination indicate that this character is inconsistent and phenotypically variable. Distinctions amongst most of the 11 currently recognized species within each of these three genera are similarly ambiguous. This study compared currently accepted diagnostic characters amongst members of these three genera and incorporated mitochondrial DNA and nuclear DNA sequencing to assess taxonomic distinctions. Specimens were obtained from throughout the range of all three genera. Molecular data supported a monophyletic grouping, which we have placed under the senior generic name Dichrometra, based on a level of intraspecies divergence similar to that in other featherstar taxa, with four distinct species-level clades: palmata Müller, 1841, flagellata Müller, 1841, gyges Bell, 1884, and brachypecha H.L. Clark, 1915, the latter two resurrected from synonymy under palmata. Amongst these, proportions of proximal pinnules contributed only to the diagnosis of D. brachypecha. These species and the genus are redescribed. However, new diagnostic morphological characters remain, because they are needed to corroborate the four clades distinguished by molecular data. Because no sequence data were available from specimens identifiable as the remaining nine nominal species, we maintain them as accepted, pending further information.

Key words:

• brachypecha
• Dichrometra
• featherstar
• flagellata
• gyges
• palmata
• phylogenetics

Acknowledgements

We thank Alison Miller (University of Guam), Mindi Summers (now University of Calgary), Tertius Kammeyer (Sorido Bay Resort), Inayat Al-Hakim and Indra Vimono (Indonesian Institute of Sciences [Lembaga Ilmu Pengetahuan Indonesia]), and Simon Leatemia (Universitas Papua, Manokwari) for their help with field collections and logistics in Raja Ampat, Indonesia. Indonesian samples were collected under permit to G. Rouse. We thank Philippe Bouchet (Muséum national d'Histoire naturelle, Paris), who invited GWR to be part of the ‘Papua New Guinea Revisited’ expedition in Madang, Papua New Guinea, and to James Thomas (Nova Southeastern University) and the Christensen Foundation for additional support and funding to join this trip. We thank Harim Cha (Scripps Institution of Oceanography, University of California San Diego, CA), Thierry Laperousaz (South Australian Museum, Adelaide, SA), and John Slapcinsky (Florida Museum of Natural History, Gainesville, FL), for their help arranging loans of specimens. We also thank Gustav Paulay for letting us examine the many specimens he collected from around the globe. Papua New Guinea specimens were collected by M. Summers and G. Rouse as part of the ‘Papua New Guinea Revisited’ expedition to Madang, Papua New Guinea. We would like to thank Tan Koh Siang for inviting C. Messing to participate in the Comprehensive Marine Biodiversity Survey of Singapore, during which many specimens were collected, and which was supported by the Air Liquide Group, Asia-Pacific Breweries Singapore, Care-for-Nature Trust Fund, and the Keppel Group.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplemental data

Supplemental data for this article can be accessed here: https://doi.org/10.1080/14772000.2017.1375044.

Additional information

Funding

This research was funded by National Science Foundation [grant number DEB-1036219 (to C. Messing)], [grant number DEB-1036368 (to G. Rouse.)]; Division of Environmental Biology.