Abstract
DNA sequencing of the plastid encoded rbcL gene supported by morpho-anatomical features reveals Gracilaria parva sp. nov. from Panama and Ecuador in the tropical eastern Pacific Ocean. In the rbcL phylogram, G. parva occurs in a clade sister to the western Atlantic species G. galatensis. Morphologically and anatomically, G. parva is distinguished from two similar, described tropical eastern Pacific species, G. brevis and G. veleroae by its small size, to 2.5 cm tall with branch widths mostly <2 mm occasionally to 4 mm, and by its two to three cell layered cortex. Gracilaria brevis and G. veleroae are taller, have wider branches, and a one cell layered cortex. DNA sequencing is needed to resolve the many diminutive species in the tropical eastern Pacific, particularly those occurring in turf communities. DNA sequencing of historical type specimens from the 19th and 20th centuries is also needed to correctly apply names in this region.
Highlights
Gracilaria Greville is an economically important genus of red algae as a producer of agarans [1]
Duplicate Ecuadoran voucher specimens from the same individual were deposited in NCU and at USFQ and Panamanian specimens were deposited at WNC and PMA
Specimens from Panama and Ecuador of the studied tropical eastern Pacific species of Gracilaria were resolved in a clade with two western Atlantic species, G. gurgelii Freshwater from the northwest Gulf of Mexico and G. galatensis Gurgel, Fredericq and J.N
Summary
Gracilaria Greville is an economically important genus of red algae as a producer of agarans [1] It is a speciose genus, currently with 193 species recognized primarily from tropical and subtropical waters worldwide [2]. About 40% of the species of Gracilaria were named in the 19th century; the rest more recently, starting in the first decade of the 21st century with the use of DNA sequences to distinguish species. Eleven species of Gracilaria have been reported from the tropical eastern Pacific mainland coasts of Mexico south through Ecuador (Table 1) Some of these are likely temperate species reaching their southern limits on the Mexican coast, or incorrect identifications of species with Atlantic Ocean type localities
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