Cryptic diversity and phylogeographic patterns of <italic>Plocamium telfairiae</italic> and <italic>P. cartilagineum</italic> (Plocamiales, Rhodophyta) in the Northwest Pacific

Abstract

Cryptic diversity refers to two or more distinct species classified as a single species due to lack of morphological difference. Although Plocamium Lamouroux has potential applications in biotechnology, several phylogenetic studies suggest the presence of cryptic diversity within the genus that requires further phylogenetic evaluation. Here, we investigated two species of Plocamium, P. “cartilagineum” and P. “telfairiae”, in the Northwest (NW) Pacific. The aims of this study are to identify potential cryptic species by analyzing the genetic differences between the species from their type localities and specimens from the NW Pacific, to characterize their population genetic diversity and structure, and to find potential hotspots with high intraspecific genetic diversity in Korea. A reconstructed phylogenetic tree based on mitochondrial 5′ region of cytochrome c oxidase subunit I (COI-5P) and plastid ribulose-1,5-bisphosphate carboxylase / oxygenase large subunit (rbcL) with molecular delimitation methods revealed significant differences as distinct species in the genus Plocamium. Comparison with specimens from their type localities indicated the presence of two cryptic species in the NW Pacific, including Plocamium luculentum sp. nov. The phylogeographic study for both species showed low genetic differences among populations, demonstrating genetic connectivity within the NW Pacific. These findings could promote the discovery of other morphologically and ecologically similar but phylogenetically different Plocamium species worldwide, which is essential for conservation assessments.

Molecular phylogeny and genetic diversity of the economic seaweed Meristotheca (Gigartinales, Rhodophyta) in the northwest Pacific, with a description of M. pilulaora sp. nov

“…The majority haplotype, MK01, was the common ancestor and the most widespread haplotype because of its prevalence in all the localities analyzed. We found that COI-5P sequences from M. pilulaora showed relatively lower haplotype diversity (Hd = 0.547) than COI-5P sequences from other red macroalgae in the northwest Pacific (Hd = 0.809 in Plocamium luculentum [Yang and Kim 2023]; Hd = 0.665 in Gracilaria vermiculophylla [Zhong et al 2020]; Hd = 0.626 in Chondrus ocellatus [Yang and Kim 2022]; Hd = 0.530 in Chondrus nipponicus [Yang and Kim 2022]). Interestingly, the pattern of the haplotype network of M. pilulaora was similar to that of other red macroalgae in Korea, which showed one or two prevailing haplotypes distributed widely, and several haplotypes derived from the prevailing haplotypes (Yang et al 2021a, b;Yang and Kim 2022).…”