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To address the taxonomic uncertainty of Sporolithon species named in the early to mid-20th century, targeted PCR sequencing was performed on eight historical type specimens and on recently collected specimens. Six type specimens amplified for the rbcL gene and were Sanger sequenced yielding sequences ranging in length from 118 to 280 base pairs (bp). One, S. australasicum, failed to amplify and another, S. howei, was amplified for the psbA gene yielding a sequence 544 bp in length. The 118 bp long rbcL sequence of the lectotype of S. crassiramosum showed that it is a later, heterotypic synonym of S. molle. The rbcL sequences of type specimens of S. episoredion, S. schmidtii, S. sibogae and S. timorense ranged from 118 to 228 bp, and each is a distinct species. The 544 bp long psbA sequence of S. howei is also unique. The 280 bp long rbcL sequence of the lectotype of S. durum did not match any sequence with that name in any public repository, including the previously published complete plastome and mitogenome sequences. However, it was identical in sequence to a specimen in GenBank from the southern coast of Western Australia as well as several other sequences generated from field-collected specimens from the states of South Australia and Western Australia. The rhodolith specimens from New Zealand previously called S. durum are S. nodosum sp. nov. The species is endemic to New Zealand. The epilithic specimens from New Zealand previously called S. durum are S. immotum sp. nov., which is also found along the southeastern coast of Australia. Sporolithon crypticum sp. nov. is described from the southern coast of Western Australia. RAxML and Bayesian phylogenetic analyses of Sporolithon psbA and rbcL sequences are congruent between the two plastid encoded genes. DNA sequencing of type specimens of species of corallines is demonstrated to be the only reliable method to correctly apply names.
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Sporolithon sinusmexicanum sp. nov. (Sporolithales, Rhodophyta): a new rhodolith-forming species from deepwater rhodolith beds in the Gulf of Mexico
Sporolithon is a non-geniculate, marine taxon that occurs in tropical to subtropical and warm temperate habitats worldwide. On the basis of specimens collected from offshore Louisiana and Florida in the Gulf of Mexico, Sporolithon sinusmexicanum sp. nov. is described. rbcL and psbA sequence analyses showed that S. sinusmexicanum is closely related to Sporolithon yoneshigueae (type locality: Bahia, Brazil). These two species can be distinguished by the number of rosette cells (10–12 in S. sinusmexicanum vs. 19–24 in S. yoneshigueae) and by the habit of the tetrasporangial structures after spore release (sloughed off in S. sinusmexicanum vs. overgrown and buried in Sporolithon yoneshigueae).
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- Award ID(s):
- 1754504
- PAR ID:
- 10058254
- Date Published:
- Journal Name:
- Phytotaxa
- Volume:
- 350
- Issue:
- 2
- ISSN:
- 1179-3163
- Page Range / eLocation ID:
- 135 - 146
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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DNA sequence analysis of plastid-encoded psbA and rbcL loci, and nuclear-encoded LSU rDNA of rhodolith-forming specimens of Sporolithales from Brazil and the northwestern Gulf of Mexico reveal that they belong to an unnamed species of Sporolithon (Sporolithaceae). Sporolithon amadoi sp. nov. is morpho-anatomically characterized by a vegetative thallus reaching more than 20 cell layers, a tetrasporophyte with tetrasporangial sori slightly raised above the thallus surface that become overgrown and buried after spore release, and by cruciately divided tetrasporangia with pores surrounded by 9–13 rosette cells. Since these morpho-anatomical features are shared with some other Sporolithon species, identification of this species can only be confirmed by DNA sequences.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/doi.org/10.11646/phytotaxa.350.2.2
