Genetic and morphological differentiation of Porphyra and Pyropia species (Bangiales, Rhodophyta) coexisting in a rocky intertidal in Central Chile

Abstract

A recent molecular taxonomic study along the Chilean coast (18° S–53° S) described 18 candidate species of bladed Bangiales of which only two were formally described. Few studies focused on local genetic and morphological diversity of bladed Bangiales and attempted to determine their intertidal distribution in contrasting habitats, and none were performed in Chile. To delimit intertidal distributions of genetic species, 66 samples of bladed Bangiales were collected at Maitencillo (32° S) in four zones: a rocky platform, a rocky wall, and two boulders zones surrounded by sandy and rocky bottoms, respectively. These samples were identified based on sequences of the mitochondrial COI and chloroplast rbcL markers. We also collected 87 specimens for morphological characterization of the most common species, rapidly assessing their putative species identity using newly developed species‐diagnostic (PCR‐RFLP) markers. Eight microscopic and two macroscopic morphological traits were measured. We described and named three of four species that predominate in Maitencillo (including Pyropia orbicularis): Pyropia variabilis Zapata, Meynard, Ramírez, Contreras‐Porcia, sp. nov., Porphyra luchea Meynard, Ramírez, Contreras‐Porcia sp. nov., and Porphyra longissima Meynard, Ramírez, Contreras‐Porcia, sp. nov. With the exception of Po. longissima restricted to boulders surrounded by sandy bottom, and a morphotype of Py. variabilis restricted to rocky walls, the other species/morphotypes have overlapping intertidal distributions. Except for Po. longissima, which is clearly differentiated morphologically (longest and thinnest blades), we conclude that morphology is not sufficient to differentiate bladed Bangiales. Our findings underscore the importance of refining our knowledge of intrinsic and environmental determinants on the distribution of bladed Bangiales.

Non‐Random Distribution and Ecophysiological Differentiation of Pyropia Species (Bangiales, Rhodophyta) Through Environmental Gradients

“…Recently, molecular analysis by Guillemin et al (2016) identified eighteen bladed Bangiales along the Chilean coast (genetic species). Later, Meynard et al (2019) confirmed genetically and morphologically, and with a wider sampling within contrasting intertidal habitat types, the existence of a new Pyropia species in central Chile (26°S-32°S), namely Pyropia variabilis (a sister species of Pyropia orbicularis; Fig. 1A).…”

“…, Meynard et al. ), Pyropia orbicularis was found to be distributed mostly on flat rocky platforms of the upper intertidal zone with the highest coverage during summer time, where it showed an overlapping distribution with the co‐dominant Pyropia variabilis LM (Fig. ).…”

“…Later, Meynard et al. () confirmed genetically and morphologically, and with a wider sampling within contrasting intertidal habitat types, the existence of a new Pyropia species in central Chile (26° S–32° S), namely Pyropia variabilis (a sister species of Pyropia orbicularis; Fig. A).…”

“…The green morphotype, P. variabilis GM, is notable for its characteristic olivaceous green color and is dominant on (vertical) rocky walls of the upper intertidal (Meynard et al. , Fig. B).…”

“…The large morphotype, P. variabilis LM, has a central large frond (and frequently shorter ones extending from the same disc) and occurs mainly on (horizontal) flat rocky platforms of the upper intertidal zone (just aside of rocky walls), just as P. orbicularis (Meynard et al. , Fig. C).…”