A new species of Gibsmithia (Dumontiaceae, Rhodophyta) from mesophotic depths of the Papahānaumokuākea Marine National Monument, Hawai‘i, USA

Abstract

Molecular phylogenetic and morphological analyses of Hawaiian members of the red algal family Dumontiaceae were used to clarify the species diversity of Dudresnaya and Gibsmithia from Hawaiʻi. Although no new species of Dudresnaya were detected in the analyses, D. babbittiana is newly recorded from Lalo, Manawai, and Oʻahu. A new species of Gibsmithia, G. punonomaewa A.R.Sherwood, is described here and reported from mesophotic depths (79-104 m) of the Papahānaumokuākea Marine National Monument, Hawaiʻi. This new species differs from others in the genus based on the following combination of characters: moderate thallus size (up to 11 cm), smooth and terete gelatinous lobes, presence of a stipe (which is often branched), globose carposporangia, and a non-isodiametric shaped cell subtending the tetrasporangia. This new taxon increases the number of Gibsmithia species recorded from Hawaiʻi to three. Phylogenetically, G. pun onomaewa is most closely related to G. dotyi and G. larkumii, which are both widespread in distribution. The relatively dark habitat of the mesophotic in Papahānaumokuākea Marine National Monument contrasts with the surf ace waters of tropical and subtropical habitats where most Gibsmithia species are found, further highlighting the uniqueness of the species.

Phylogeography of Amansia glomerata C.Agardh (Ceramiales, Rhodomelaceae) in Hawai‘i: A Single Species with High Divergence

“…2). Of the four lineages presented here, three were described by Sherwood et al (2011) and we separate Lineage 4 from Lineage 1 based on its assignment by rmaverick as a distinct group. Lineages 2 and 3 were equidistant from the central lineage, 4, while Lineage 1 was closer to Lineage 4 (Fig.…”

“…In Hawai'i it is typically abundant (Doty 1971), perennial (Abbott 1999), provides food for herbivores including turtles (Miyal & Balazs 1993), forms expansive monospecific stands, and hosts diverse invertebrate populations (Russo 1989). Furthermore, the species was described from the "Sandwich Islands" (Hawai'i) and a mitochondrial cytochrome c oxidase subunit I (COI) sequence of the lectotype is available (Sherwood et al 2011). Preliminary research into the molecular and morphological diversity of A. glomerata has raised a number of questions that remain unresolved.…”

“…Preliminary research into the molecular and morphological diversity of A. glomerata has raised a number of questions that remain unresolved. Sherwood et al (2011) investigated the molecular signatures of the tribe Amansieae in the Hawaiian Islands and suggested the taxon may warrant splitting after more extensive molecular work. Of the markers used by Sherwood et al (2011), COI was the most informative.…”

“…Sherwood et al (2011) investigated the molecular signatures of the tribe Amansieae in the Hawaiian Islands and suggested the taxon may warrant splitting after more extensive molecular work. Of the markers used by Sherwood et al (2011), COI was the most informative. Estimates of genetic divergence based on COI by Sherwood et al (2011) demonstrated a divergence of up to 3.6% (22 out of 603 bp) between lineages of A. glomerata, falling roughly between those values typical of intraspecific variation and interspecific variation.…”

“…Of the markers used by Sherwood et al (2011), COI was the most informative. Estimates of genetic divergence based on COI by Sherwood et al (2011) demonstrated a divergence of up to 3.6% (22 out of 603 bp) between lineages of A. glomerata, falling roughly between those values typical of intraspecific variation and interspecific variation. Typical intraspecific thresholds for COI in Rhodophyta are 0.0-0.7% while interspecific variation can be very broad from 2.6-10.5% (Saunders 2005;Robba et al 2006;Clarkston & Saunders 2013;Savoie 2017).…”