Status, morphology, and phylogenetic relationships of Iyengaria (Scytosiphonaceae, Phaeophyceae), a brown algal genus with a disjunct distribution in the Indian Ocean

Abstract

The taxonomy, classification, and phylogenetic relationships of the brown seaweed genus Iyengaria with other members of the family Scytosiphonaceae remain poorly understood. In this study, we addressed some problems in the systematics (taxonomic and classification status) and phylogenetic position of Iyengaria based on our studies on the generitype Iyengaria stellata from Kuwait and South Africa. We confirm that I. stellata is conspecific with Colpomenia capensis based on molecular and morpho-anatomical data and that the species has a disjunct distribution within the Indian Ocean. Also, the distinguishing features of two Iyengaria species (I. nizamuddinii and 'I. lobocylindrica') described from Karachi, Pakistan, are within the morphological range of I. stellata. Hence, these two taxa are considered here as junior heterotypic synonyms of I. stellata. Our molecular phylogenetic analyses suggested the polyphyly of the genus Iyengaria, with the recently described Iyengaria quadriseriata from India forming close associations with Rosenvingea intricata. As such, we remove I. quadriseriata from the genus Iyengaria and relegate it as a synonym of R. intricata. Consequently, by recognizing only one species, our proposals considerably reduce the species diversity in the genus. Moreover, our culture studies suggested that I. stellata exhibits an alternation of heteromorphic generations, similar to other species in the Scytosiphonaceae. Under culture conditions, I. stellata also produced plurangia on microthalli, confirming its affinity with other phylogenetically close relatives in the 'Hydroclathrus group' of the family Scytosiphonaceae such as Colpomenia, Rosenvingea, and Chnoospora.

Colpomenia borea sp. nov. (Scytosiphonaceae, Phaeophyceae) from Japan and Far East Russia

“…Problems of paraphyly or polyphyly in some scytosiphonacean genera including Colpomenia have been shown in previous molecular phylogenetic studies using not only a single gene but also multiple genes (Santiañez et al 2018(Santiañez et al , 2020. Similarly, members of the genus Colpomenia did not form a clade in our analyses that is the clade of C. peregrina, C. claytoniae, C. expansa, and C. borea was well supported but separated from other Colpomenia species including the generitype C. sinuosa.…”

“…Problems of paraphyly or polyphyly in some scytosiphonacean genera including Colpomenia have been shown in previous molecular phylogenetic studies using not only a single gene but also multiple genes (Santiañez et al . 2018, 2020). Similarly, members of the genus Colpomenia did not form a clade in our analyses that is the clade of C .…”

Asterocladon ednae sp. nov. (Asterocladales, Phaeophyceae) from the Philippines

“…Total genomic DNA was extracted from cultured thalli, following the methods described in Santiañez et al (2020). Polymerase chain reaction (PCR) amplification was performed for rbcL and psaA genes, using TaKaRa Ex Taq DNA polymerase (Takara Bio, Otsu, Japan) and primers which were previously published (Kogame et al 1999;Yoon et al 2002) or designed in this study as shown in Table S2.…”

French Polynesian Scytosiphonaceae (Ectocarpales, Phaeophyceae): A combined molecular and morphological approach to their diversity and systematics

“…In recent years, the family Scytosiphonaceae Farlow (Ectocarpales, Phaeophyceae) has received a fair amount of attention, and major taxonomic revisions have been made with the help of molecular data (Santiañez et al., 2020; Santiañez & Kogame, 2019, 2022; Santiañez, Lee, et al., 2018; Santiañez, Macaya, et al., 2018; Santiañez & West, 2019; Santiañez & Wynne, 2019). According to AlgaeBase (Guiry & Guiry, 2023), at the time of writing, the family Scytosiphonaceae consisted of 65 species belonging to 20 genera— Chnoospora J. Agardh (2 species), Colpomenia (Endlicher) Derbès & Solier (10 species), Dactylosiphon Santiañez, K.M.…”