Beneath the hairy look: the hidden reproductive diversity of the Gibsmithia hawaiiensis complex (Dumontiaceae, Rhodophyta)

Abstract

The tropical alga previously recognized as Gibsmithia hawaiiensis (Dumontiaceae, Rhodophyta) was recently suggested to represent a complex of species distributed throughout the Indo-Pacific Ocean and characterized by a peculiar combination of hairy (pilose) gelatinous lobes growing on cartilaginous stalks. Phylogenetic reconstructions based on three genetic markers are presented here with the inclusion of new samples. Further diversity is reported within the complex, with nine lineages spread in four major phylogenetic groups. The threshold between intra- and interspecific relationships was assessed by species delimitation methods, which indicate the existence of 8-10 putative species in the complex. Two species belonging to the G. hawaiiensis complex are described here: Gibsmithia malayensis sp. nov. from the Coral Triangle and Gibsmithia indopacifica sp. nov., widely distributed in the Central and Eastern Indo-Pacific. Morphological differences in the vegetative and reproductive structures of the newly described species are provided and compared to the previously described species of the complex. Additional lineages represent putative species, which await further investigation to clarify their taxonomic status. Gibsmithia hawaiiensis sensu stricto is confirmed to be endemic to the Hawaiian Islands, and Gibsmithia eilatensis is apparently confined to the Red Sea, with an expanded distribution in the region. New records of the G. hawaiiensis complex are reported from Egypt, Saudi Arabia, Indonesia, Philippines, and the Federated States of Micronesia, indicating that the complex is more broadly distributed than previously considered. The isolated position of Gibsmithia within the Dumontiaceae is corroborated by molecular data.

Small tropical islands as hotspots of crustose calcifying red algal diversity and endemism

“…Of the 154 species found in this study, only ten of them matched (≥ 98% COI-5P similarity) sequences of described species, four of those were only described from Guam last year (Mills and Schils, 2021), suggesting that many of these CCRA species are possibly new to science. These findings are also consistent with recent studies that revealed extensive degrees of endemism and cryptic diversity within Guam's seaweed flora (Verbruggen and Schils, 2012;Gabriel et al, 2017;Leliaert et al, 2018;Gabriel et al, 2019;Mills and Schils, 2021;Vieira et al, 2022). Additionally, the CCRA diversity reported herein is greater than those of much larger coastal and oceanic ecosystems, including those documented in recent studies in New Zealand and Brazil (Twist et al, 2019;Sissini et al, 2021), in other barcoding blitzes in Hawaii, Taiwan, Tunisia, and…”

Patterns and drivers of species diversity in the Indo‐Pacific red seaweed Portieria

“…Compared to marine fish and invertebrates with planktonic larvae, most seaweeds are poor dispersers because their spores and zygotes are typically short-lived and negatively buoyant (Kinlan & Gaines, 2003). As a result, many seaweed species have restricted geographical ranges and molecular data indicate that several allegedly widely distributed species in fact represent cryptic species with narrow distributions (e.g., Gabriel et al, 2017;Saunders, 2005;Zuccarello & West, 2003).…”

Diversity and distribution of marine benthic algae and seagrasses in the tropical Kimberley, Western Australia

“…has been shown to be misapplied and is now referred to the Indonesian species Dichotomaria sibogae (Weber Bosse) Huisman et al (Huisman et al 2018). Similarly, Gibsmithia hawaiiensis Doty is now regarded to be restricted to the Hawaiian Islands and the Kimberley species is referred to Gibsmithia indopacifica Gabriel et al (Gabriel et al 2017).…”