DNA sequencing resolves species of Spongites (Corallinales, Rhodophyta) in the Northeast Pacific and South Africa, including S. agulhensis sp. nov.

Abstract:

DNA sequence data from a 296 base pair variable region of the plastid encoded rbcL gene was obtained from 19th century type material of Spongites decipiens and of Lithophyllum tumidum (=Pseudolithophyllum neofarlowii) and matched to field-collected material, confirming the application of these specific epithets in the northeast Pacific. Phylogenetic analyses of separate and concatenated rbcL and psbA gene sequences show that both species belong in Spongites. Based on DNA sequences, the distribution of S. decipiens is confirmed from Haida Gwaii, British Columbia, Canada, south to its type locality at San Pedro, Los Angeles County, California, whereas, Spongites tumidum is distributed from near Sitka, Alaska, to Monterey County, California. Sequence data from S. decipiens and South African specimens called Spongites yendoi confirm anatomical studies that these two species are distinct but that a previously undescribed, cryptic species, Spongites agulhensis, also is present in South Africa. Anatomically and morphologically S. agulhensis is very similar to both northeast Pacific S. decipiens and South African S. yendoi, differing from the former by a single anatomical character and from the latter by two anatomical characters. Anatomy, ecology and distributions are useful in separating the South African species of Spongites, as well as the northeast Pacific species. Sequence divergence values align with biogeographic patterns and not with anatomical similarities for these Spongites species. We question the practice of placing into synonymy geographically widely separated non-geniculate coralline algal species based solely on anatomical features that likely have resulted from convergent evolution.

Key Words::

• psbA
• rbcL
• Spongites decipiens
• Spongites tumidum
• Spongites yendoi
• Sequencing type material

ACKNOWLEDGEMENTS

We thank the Department of Biodiversity and Conservation Biology at the University of the Western Cape for providing funding and research equipment, and the South African National Research Foundation (NRF) for research grants to GWM and AC. Adrian Josephs provided valuable assistance with the operation of the SEM. Dr Gary Saunders generously provided unpublished DNA sequences. We thank Dr S. C. Lindstrom, Mr W. Wood and students and teacher, Mr Larry Madrigal, of the Saint Joseph High School Science Research Institute in Santa Maria, California, for providing specimens. Dr Kathy Ann Miller (UC) kindly shared with us her knowledge of an earlier specific epithet that was found by and is documented in INA (Index Nominum Algarum, http://ucjeps.berkeley.edu/INA.html). Dr Wilson Freshwater, DNA Analysis Core Facility, University of North Carolina, Wilmington, provided sequencing support, and Dr Todd Vision provided research space and equipment to PWG, who also acknowledges a private family trust for research support. A portion of this research was completed while PWG was a visiting professor at the Friday Harbor Labs, University of Washington.

SUPPLEMENTARY DATA

Supplementary data associated with this article can be found online at http://dx.doi.org/10.2216/15-38.1.s1.