Systematics, distribution, and sexual compatibility of six Scytosiphon species (Scytosiphonaceae, Phaeophyceae) from Japan and the description of four new species. Issue 2 (18th December 2020)

• Record Type: Journal Article
• Authors: Hoshino, Masakazu; Tanaka, Atsuko; Kamiya, Mitsunobu; Uwai, Shinya; Hiraoka, Masanori; Kogame, Kazuhiro
• Editors: Lane, C.
• Is Part Of: Journal of phycology. Volume 57:Issue 2(2021)
• Page Start: 416
• Page End: 434
• Publication Date: 2020-12-18
• Subjects: cox1 -- cryptic species -- gametic incompatibility -- phylogeography -- rbcL -- reinforcement -- reproductive isolating barrier -- species complex -- taxonomy; Algae -- Periodicals; 579.8
• DOI: 10.1111/jpy.13089
• Languages: English
• ISSNs: 0022-3646

Abstract

Abstract : The brown alga Scytosiphon lomentaria (Scytosiphonaceae, Ectocarpales) has been reported from cold and warm waters worldwide. Although previous molecular phylogenetic studies and crossing experiments have shown that it is a complex of multiple distinct species, the taxonomic position and accurate distribution of each species have remained largely unclear. For the S. lomentaria complex from Japan, our cox 1 and rbc L phylogenetic analyses detected six species. In addition to five previously detected species (species Ia–Va), one species (species VI) was newly found in the subtropical area, Okinawa Island. Species VI was recovered as a sister to species Ia–Va in rbc L. Based on the morphological and phylogenetic data, we concluded that species Ia is S. lomentaria, species IIIa is S. promiscuus, and the other four species are newly described: S. shibazakiorum for species IIa, S. tosaensis for species IVa, S. arcanus for species Va, and S. subtropicus for species VI. The cox 1‐based analysis also showed that S. lomentaria, S. shibazakiorum, and S. promiscuus have worldwide distributions, while the other three species were not found outside of Japan. In Japan, except for S. subtropicus, distributions of these species overlapped. Our crossing experiments showed that gametic incompatibility (pre‐zygotic barrier) was less developed between the allopatric species (i.e., S. subtropicus and others) compared with the sympatric species. It may suggest that pre‐zygotic barriers have evolved among the sympatric species due to reinforcement.