Morphology and molecular relationships of Leptofauchea rhodymenioides (Rhodymeniales, Rhodophyta), a new record for Japan

Abstract

Leptofauchea rhodymenioides Taylor (Faucheaceae, Rhodymeniales) is reported from Japan for the first time, based on detailed morphological studies and molecular phylogenetic analyses of nuclear-encoded small subunit ribosomal RNA (SSU rRNA) and plastidencoded rbcL gene sequences. This is the first report of male gametophytes and detailed carposporophyte development in the genus Leptofauchea. This species is characterized as follows: (i) flat, membranous, and regularly and dichotomously branched thalli; (ii) the older blades are constricted below the apices; (iii) the cortex is composed of a continuous layer with an irregularly arranged outer layer, and the medulla of two to three incomplete layers; (iv) gametophytes are dioecious; (v) in males, the cortical cells cut off two to three spermatangial mother cells, which produce terminal spermatangia; (vi) in females, the procarp is composed of a three-celled carpogonial branch and a two-celled auxiliary cell branch; (vii) upon fertilization, the carpogonium directly contacts the auxiliary cell; (viii) the auxiliary mother cell fuses with vegetative cells, and forms a large trunk-like fusion cell; (ix) gonimoblast filaments develop outwardly, and transform completely into carposporangia; (x) the carposporophyte is covered with a pericarp with a well-defined tela arachnoidea; (xi) the mature cystocarp is spherical, has an ostiole, and protrudes from the blade margins; and (xii) the cruciately divided tetrasporangia are formed in nemathecia, produced laterally from paraphyses or terminally on short filaments. Molecular analyses suggest that Leptofauchea forms a strong sister alliance with the genus Webervanbossea. The families Faucheaceae and Lomentariaceae, and the genera Leptofauchea and Webervanbossea are monophyletic, but the latter two genera are not included in the Faucheaceae.

Morphology and molecular relationships of Leptofauchea leptophylla comb. nov. (Rhodymeniales, Rhodophyta) from Japan

“…The LSU rRNA analyses indicate that our new sample of L. leptophylla is most closely related to L. rhodymenioides. Leptofauchea leptophylla is distributed from central to southern Japan, Korea and the Philippines, while L. rhodymenioides is distributed in northeastern Honshu, Japan; Florida; and the Caribbean islands (Taylor 1942;Dalen & Saunders 2007;Suzuki et al 2010). Leptofauchea leptophylla differs from L. rhodymenioides by its iridescence in water and having a short, well-defined stipe.…”

“…Total DNA was extracted using a DNeasy Plant Mini Kit (QIAGEN, Tokyo, Japan). We performed LSU rRNA sequencing procedures for SSU rRNA according to Suzuki et al (2010). The primers used were T01-V, F449-G, T04-28F and T05-T15 (Freshwater et al 1999;Harper & Saunders 2001a).…”

“…Leptofauchea auricularis has not been reported since Dawson's (1963) original description, which did not include information on reproductive structures; hence, the taxonomic affinity of L. auricularis remains ambiguous. Suzuki et al (2010) found L. rhodymenioides in northeastern Japan, the first record of the genus in the northwestern Pacific.…”

Schizymenia dubyi(Rhodophyta, Schizymeniaceae), a new introduced species in Argentina

“…Total DNA was extracted using the DNeasy Plant Mini Kit (QIAGEN, Tokyo, Japan). RbcL gene sequencing procedures were followed as described in Suzuki et al (2010). RbcL sequences from seven taxa were aligned using ClustalX (Thompson et al 1997).…”

First report of Halopeltis (Rhodophyta, Rhodymeniaceae) from the non-tropical Northern Hemisphere: H. adnata (Okamura) comb. nov. from Korea, and H. pellucida sp. nov. and H. willisii sp. nov. from the North Atlantic

“…These studies have discovered cryptic diversity within the order (e.g., Saunders et al 2006, Ballantine and LozadaTroche 2008, Schneider and Lane 2008, Saunders and McDonald 2010, as well as allowing for generic discovery and realignment in the Rhodymeniaceae, Fryeellaceae, Faucheaceae, Hymenocladiaceae, Champiaceae and Lomentariaceae (e.g., Millar et al 1996, Saunders et al 1999, 2006, Wilkes et al 2005, Dalen and Saunders 2007, Le Gall et al 2008, Saunders and McDonald 2010, Suzuki et al 2010. Combined, such molecular-assisted, alpha taxonomic (MAAT) studies have begun to demonstrate a significantly clearer picture of species richness and evolutionary relationships within this order than was known in the 20th century (Bliding 1928, Kylin 1931, 1956, Sparling 1957.…”