The habitat-modifying red alga Ramicrusta on Pacific reefs: A new generic record for the Tropical Northwestern Pacific and the description of four new species from Guam

Matthew S Mills; Tom Schils

doi:10.1371/journal.pone.0259336

The habitat-modifying red alga Ramicrusta on Pacific reefs: A new generic record for the Tropical Northwestern Pacific and the description of four new species from Guam

PLoS One. 2021 Nov 15;16(11):e0259336. doi: 10.1371/journal.pone.0259336. eCollection 2021.

Authors

Matthew S Mills^{1

2}, Tom Schils¹

Affiliations

¹ Marine Laboratory, University of Guam, Mangilao, Guam.
² School of Science, Technology, and Engineering, University of the Sunshine Coast, Sippy Downs, Queensland, Australia.

Abstract

The genus Ramicrusta (order Peyssonneliales) is a new record for Micronesia, with range expansions of Ramicrusta fujiiana and R. lateralis to Guam. In addition, four species (Ramicrusta adjoulanensis, R. asanitensis, R. labtasiensis, and R. taogamensis) are newly described from Guam using molecular and anatomical characters. Ramicrusta lateralis specimens from Guam share most anatomical features with the holotype description from Vanuatu, but the plants from Guam are more tightly adherent, rigid, and robust than those of Vanuatu. Ramicrusta adjoulanensis possesses a well-developed epithallus with frequent cell fusions, secondary pit connections, and lacking hair bases or trichocytes, similar to Ramicrusta bonairensis. Ramicrusta adjoulanensis differs from other Ramicrusta species in having occasionally free margins and being attached by frequently produced, relatively long rhizoids (75-100 μm long). Ramicrusta asanitensis shares features with many other species, but the thickness of the crust (upwards of 2 mm thick), heavy calcification in the epithallus, and the extent of secondary, tertiary, and quaternary growth, differentiate it from other Ramicrusta species. Ramicrusta labtasiensis shares features with its close relative Ramicrusta lateralis but possesses frequent, robust, and relatively long rhizoids (75-95 μm long) throughout its entire undersurface. Ramicrusta taogamensis resembles its close relative Ramicrusta appressa but is primarily distinguished by its generally well-developed epithallus with occasional secondary pit connections and cell fusions. The six species reported here make Guam equal to Vanuatu in currently having the highest known species richness of Ramicrusta in the world.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Ecosystem
Guam
Micronesia
Rhodophyta*

Grants and funding

This research is based upon work supported by the National Aeronautics and Space Administration (NASA; nasa.gov) and the National Science Foundation (NSF; nsf.gov) under grant numbers 80NSSC17M0052 and OIA-1946352 awarded to TS and managed through the Guam EPSCoR offices of NASA and NSF. The work for this paper was also partly funded as an award to MM by a cooperative agreement with the National Oceanic and Atmospheric Administration (NOAA; noaa.gov), Project NA14OAR4170116, which is sponsored by the University of Guam Sea Grant from NOAA Office of Sea Grant, Department of Commerce. Any opinions, findings, and conclusions or recommendations expressed in this manuscript are those of the authors and do not necessarily reflect the views of NASA, NSF, NOAA or any of their subagencies. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.