<italic>Fissipedicella orientalis</italic> gen. et sp. nov. (Ralfsiales, Phaeophyceae), a new crustose brown alga from Korea based on molecular and morphological analyses

Abstract

The crustose brown algal family Ralfsiaceae comprises four genera: Analipus, Endoplura, Heteroralfsia, and Ralfsia. This study provides a detailed description of Fissipedicella orientalis gen. et sp. nov. based on molecular and morphological analyses. Our phylogenetic analyses from rbcL and concatenated dataset (rbcL + 5′ region of cytochrome c oxidase subunit I [COI-5P]) reveal that specimens collected in Korea are nested in a distinct new clade within Ralfsiaceae with robust bootstrap support and Bayesian posterior probabilities. The sequence divergences for rbcL and COI-5P between F. orientalis and other genera within Ralfsiaceae are 7.4–10.1 and 17.5–21.2%, respectively. Fissipedicella orientalis is characterized by crustose thalli with a hypothallial basal layer and erect perithallial filaments, tufts of hairs in pits, a single chloroplast per cell, plurangia with 1–3 sterile cells, and unangia on stalks composed of 1–6 vertically or obliquely cleaved cells. We propose that F. orientalis can be recognized as a new genus-level taxon within Ralfsiaceae, even though a single species represents it. Our new genus, Fissipedicella, is distinguished from the other members within the Ralfsiaceae by the type of thallus, the number of chloroplasts and tufts of hairs in pits, and the development of unangia.

Ramipedicella gen. nov. (Ralfsiales, Phaeophyceae): a new crustose brown algal genus including two species, Ramipedicella miniloba sp. nov. and Ramipedicella longicellularis comb. nov.

“…This species has been observed in various localities along the eastern coast (Busan and Ulsan), western coast (Baekryeongdo, Boryeong, Buan, and Taean) and southern coast (Namhae, Alvarez and González-González 2003, Lim et al 2007, León-Alvarez et al 2017, Parente et al 2021, Oteng'o et al 2023b). The diverse morphological features observed in unangia, including stalk-like filaments, paraphyses, and the positioning of unangia, suggest that these reproductive structures could carry taxonomic importance within distinct groups at different levels within the Ralfsiales (Oteng'o et al 2023b). According to Oteng'o et al (2023b), there are two main types of unangia: those with paraphyses and those without.…”

“…In recent studies conducted by Oteng'o et al (2021Oteng'o et al ( , 2022Oteng'o et al ( , 2023aOteng'o et al ( , 2023b Won 2020). These findings showed the possibility that Korea may be one of the hotspots for crustose brown algal biodiversity (Oteng'o et al 2023b).…”

“…For the analysis of rbcL sequences, we used the same outgroup and Mega X (Kumar et al 2018) to determine the optimal model. ML analysis was estimated by the Tamura 3-parameter + Γ + I Berkeley (Lim et al 2007, Silberfeld et al 2014, Parente and Saunders 2019, Guiry and Guiry 2023, Oteng'o et al 2023b. Traditionally, the recognition of genera within Ralfsiaceae has been based on morphological characters such as thallus type, number of sterile cells on plurangia, number of chloroplasts per cell, and the development of unangia (Tanaka and Chihara 1981b, Lim et al 2007, León-Álvarez et al 2017, Oteng'o et al 2021, Parente et al 2021.…”

“…However, due to the morphological simplicity and external similarities among them, the classification of these genera has been challenging. Recent molecular analyses are increasing the taxonomic resolution of these genera within Ralfsiaceae, providing a clearer depiction of their phylogenetic relationships (Lim et al 2007, Silberfeld et al 2014, Parente and Saunders 2019, Oteng'o and Won 2020, Oteng'o et al 2021, 2023a, 2023b.…”

“…was the first to describe the Ralfsiaceae, which has been recognized as the largest family within the order Ralfsiales. Ralfsiaceae has been characterized by rounded to irregularly spreading crust, basal layer composed of radiating appressed filaments, and tightly appressed erect vegetative filaments, single or few chloroplasts per cell, plurangial reproductive structures topped with sterile cell(s), unangia accompanied by paraphysis on the terminal part of erect filaments, diplohaplontic and isomorphic or heteromorphic life history (Farlow 1881, Setchell and Gardner 1924, Abbott and Hollenberg 1976, Womersley 1987, Parente and Saunders 2019, Oteng'o et al 2023b. Currently, the family Ralfsiaceae comprises five recognized genera: Analipus Kjellman, Endoplura Hollenberg,…”