null
(Ed.)
Survey cruises by the National Oceanic and Atmospheric Administration (NOAA) in 2016
and 2019 yielded specimens of an undetermined red alga that rapidly attained alarming levels
of benthic coverage at Pearl and Hermes Atoll, Papahānaumokuākea Marine National
Monument, Hawai‘i. By 2019 the seaweed had covered large expanses on the northeast side
of the atoll with mat-like, extensive growth of entangled thalli. Specimens were analyzed
using light microscopy and molecular analysis, and were compared to morphological descriptions
in the literature for closely related taxa. Light microscopy demonstrated that the specimens
likely belonged to the rhodomelacean genus Chondria, yet comparisons to taxonomic
literature revealed no morphological match. DNA sequence analyses of the mitochondrial
COI barcode marker, the plastidial rbcL gene, and the nuclear SSU gene confirmed its
genus-level placement and demonstrated that this alga was unique compared to all other
available sequences. Based on these data, this cryptogenic seaweed is here proposed as a
new species: Chondria tumulosa A.R.Sherwood & J.M.Huisman sp. nov. Chondria tumulosa
is distinct from all other species of Chondria based on its large, robust thalli, a mat-forming
tendency, large axial diameter in mature branches (which decreases in diameter with subsequent
orders of branching), terete axes, and bluntly rounded apices. Although C. tumulosa
does not meet the criteria for the definition of an invasive species given that it has not been
confirmed as introduced to Pearl and Hermes Atoll, this seaweed is not closely related to any
known Hawaiian native species and is of particular concern given its sudden appearance and
rapid increase in abundance in the Papahānaumokuākea Marine National Monument; an
uninhabited, remote, and pristine island chain to the northwest of the Main Hawaiian Islands.
more »
« less