ムロネアマノリ（紅藻ウシケノリ目）の新組合せ Pyropia akasakae

Abstract

Many Japanese bladed species in Bangiales (Rhodophyta), that were originally classified in the genus Porphyra C.Agardh, have been transferred to other genera based on molecular phylogenetic analyses. The generic placement of six species, currently placed in Porphyra, has not been confirmed with sequence data. One of these, Porphyra akasakae A.Miura is distributed along the Sanriku coast, northern Honshu, Japan. Morphological observations and molecular phylogenetic analysis based on the nrSSU and rbcL genes of this species resolved it was an independent species within the genus Pyropia J.Agardh. Therefore, we propose a new combination: Pyropia akasakae (A.Miura) N.Kikuchi, Shot.Suzuki, Tamaki & Ta.Abe.

Translated Abstract

紅藻ウシケノリ目 Bangiales の属は，分子系統解析に基づき再編が行われ， Porphyra属に属していた日本産の種の多くは他のいくつかの属に移った．しかしDNA解析が行われていない6種の所属については未検討のままで，Porphyra属に残されている．そのうちの一種ムロネアマノリ Porphyra akasakae A.Miura は三陸沿岸に分布している．形態学的観察と核コードのnrSSU遺伝子および葉緑体コードのrbcL 遺伝子の塩基配列に基づく分子系統解析の結果，本種はアマノリ属 Pyropia に属する独立種であることが判明した．従って，新組合せPyropia akasakae (A.Miura) N.Kikuchi, Shot.Suzuki, Tamaki & Ta.Abe を提案する．

Traditionally, bladed species in the Bangiales (Rhodophyta) were placed in the genus Porphyra C.Agardh based on morphology. However, a global revision of the order based on molecular phylogeny was proposed, and bladed species were divided into eight genera (Sutherland et al. 2011). After that a new genus was established in the order (Sánchez et al. 2014), and now nine genera with foliose gametophytes belong to the order.

In Sutherland et al. (2011), twenty-two bladed species from Japan were classified into four genera: Boreophyllum S.C.Lindstr., N.Kikuchi, Miyata & Neefus, Miuraea N.Kikuchi, S.Arai, G.Yoshida, J.-A.Shin & Miyata, Pyropia J.Agardh and Wildemania De Toni. Miuraea was replaced by Neomiuraea N.Kikuchi, S.Arai, G.Yoshida, J.-A.Shin & Miyata in Kikuchi et al. (2018) because Miuraea was a later homonym of Miuraea Hara (Hara 1948) (Fungi). Subsequently, Porphyra yamadae T.Yoshida was recognized as synonym of Pyropia acanthophora (E.C.Oliveira & Coll) M.C.Oliveira, D.Milstein & E.C.Oliveira (Xie at al. 2015). Three new species of Pyropia: Py. kitoi (Ma.Abe, N.Kikuchi, Tamaki, Tom.Sato, Murase, Fujiyoshi & Ma.Kobayashi) D.J.Kim, T.O.Cho & B.Y.Won (Abe at al. 2021, as Neoporphyra kitoi), Py. neodentata Matsushita, Na.Takahashi & Niwa (Matsushita et al. 2025) and Py. ezokurogii Nishina & Niwa (Nishina et al. 2025), were reported from Japan, and Py. haitanensis (T.J.Chang & B.F.Zheng) N.Kikuchi & Miyata was newly reported from Japan (Sano et al. 2021). Although Yang et al. (2020) proposed to split the genus Pyropia into five genera, Zuccarello et al. (2022) proposed those genera should be restored to Pyropia because of the low confidence of branches in phylogenetic analyses. Recently, Li et al. (2025) proposed reinstating the genera that Yang et al. (2020) created. However, we follow Zuccarello et al. (2022) in this study.

Currently thirty-three bladed species of Bangiales are reported to be distributed in Japan (Matsushita et al. 2025, Nishina et al. 2025) and six species without DNA data available to confirm their generic placement remain as Porphyra. Of the Japanese species for which DNA analysis has been conducted to date, no species belonging to Porphyra have been confirmed.

Porphyra akasakae A.Miura was described as a new species by Miura (1977) based on thalli collected from the Sanriku coast of Miyagi Prefecture, northern Japan. This species is one of the six species remaining as Porphyra. In this study, we conducted morphological observations and DNA analysis of Po. akasakae based on the thalli from three localities of Sanriku coast including the type locality to clarify the taxonomic placement of the species.

Materials and Methods

Field collections and establishment of culture strains

Mature foliose thalli of Porphyra akasakae were collected from Hashikami Sanzunokawa (38°49ʹ48ʺN, 141°36ʹ14ʺE, the type locality), Kesennuma, Miyagi on 27 February 2023, Hajikami Iwaisaki (38°49ʹ39ʺN, 141°36ʹ11ʺE), Kesennuma, Miyagi on 27 February 2023 and Arato Ushihama (38°40ʹ34ʺN, 141°29ʹ34ʺE), Shizugawa Gongen, Minamisanriku, Miyagi on 28 February 2023. The thalli were chilled (to 4 °C) and sent to the Coastal Branch of Natural History Museum and Institute, Chiba within 2 days. Mature foliose thalli were washed with a brush in sterilized seawater and excised pieces (5 × 5 mm) from mature thallus portion were kept for 12 h in Petri dishes with 1/2 modified SWM-III medium (Fujiyoshi and Kikuchi 2006) under 15 °C, short-day length photoperiod (10L:14D) and 40 µmol m^-2 s^-1 light conditions. Released zygotospores were transferred to a new Petri dish with the same medium and cultured under 20 °C, short-day length photoperiod (10L:14D) and 40 µmol m^-2 s^-1 light conditions. The clean filamentous thalli were selected after a month and unialgal culture strains were established, using the same medium. The established strains were cultured under 20 °C, long-day length photoperiod (14L:10D) and 10 µmol m^-2 s^-1 light conditions using 1/2 modified SWM-III medium and the medium was replaced every 3 weeks. The parental foliose thalli of established unialgal culture strains and some other foliose thalli were pressed and deposited in the algal herbarium of the Coastal Branch of Natural History Museum and Institute, Chiba (CMNH-BA).

Morphological observation

Freshly collected foliose thalli from the field were used for morphological observations. For anatomical observations, cross-sections were made by hand using a razor blade. Materials were observed with microscopes Nikon E600 (Nikon, Tokyo, Japan), and photographs were taken with Nikon digital camera system for microscopy with DS-Fi1 camera head and DS-L2 control unit (Nikon, Tokyo, Japan).

Molecular phylogenetic analysis

Three unialgal culture strains (UM-AK1, UM-AK2 and UM-AK7) of Porphyra akasakae were used for the molecular phylogenetic studies. Strain UM-AK1 was isolated from a blade collected at Hashikami Sanzunokawa (type locality), strain UM-AK2 from a blade collected at Hajikami Iwaisaki and strain UM-AK7 from a blade collected at Arato Ushihama. A part of the cultured filamentous thalli was cut into small pieces with scissors and used for DNA extractions. Total genomic DNA was extracted from filamentous thalli using Isoplant II (Nippon Gene, Tokyo, Japan) according to the manufacturer’s instructions and stored in a refrigerator at 4 °C until use. Polymerase chain reaction (PCR) amplifications of the nuclear ribosomal SSU (nrSSU) and chloroplast rbcL genes were performed using the Biometra TOne (Analytik Jena, Jena, Germany). Primers used for PCR and sequencing are listed in Table 1. The PCR mixes contained 0.25 µL of TaKaRa Ex Taq HS, 4 µL of dNTP mixture, 5 µL of 10×Ex Taq Buffer (Takara Bio, Kusatsu, Japan), 0.5 µL of each primer (20 µM), 1 µL of template DNA (10–100 ng/µL), and 38.75 µL of water to give a final volume of 50 µL. The PCR profiles of nrSSU and rbcL were comprised of 35 cycles: 94 °C for 30 s, 52 °C for 30 s, 72 °C for 60 s and 30 cycles: 94 °C for 60 s, 48 °C for 60 s, 72 °C for 60 s, respectively. The PCR products were confirmed by electrophoresis in 1% agarose gels with SAFELOOK™ Green Nucleic Acid Stain (FUJIFILM Wako Pure Chemical Corporation, Osaka, Japan) and purified using a NucleoSpin Gel and PCR Clean-up (Macherey-Nagel GmbH & Co., Düren, Germany). Purified PCR products were sequenced using primers listed in Table 1 with an autosequencer (3730xl DNA analyzer, Applied Biosystems) by Macrogen Japan Corporation (Tokyo, Japan). The nrSSU and rbcL sequence data obtained for each primer were merged for each sample using ClustalW implemented in the MEGA X (Kumar et al. 2018) or by manual alignment. Nucleotide sequence data were submitted to DNA DataBank of Japan (DDBJ, Table 2).

Table 1. List of primers for amplification and sequencing in this study. Primers with an asterisk were used only for sequencing.

Table 2. List of accession numbers obtained from DDBJ for nrSSU and rbcL genes used in phylogenetic analyses. Asterisks indicate the accessions determined in this study.

Species	Location of collection	nrSSU	rbcL
Boreophyllum pseudocrassum	Erimo, Hokkaido, Japan	HQ687564	HQ687512
Neomiuraea migitae	Osaka Bay, Osaka, Japan	EU521642	EU521643
Porphyra akasakae UM-AK1	Hashikami-Sanzunokawa, Kesennuma, Miyagi, Japan	LC899182*	LC899185*
Porphyra akasakae UM-AK2	Hajikami-Iwaisaki, Kesennuma, Miyagi, Japan	LC899183*	LC899186*
Porphyra akasakae UM-AK7	Shizugawa Gongen, Minamisanriku, Miyagi, Japan	LC899184*	LC899187*
Porphyra purpurea	Litstock, Somerset, UK	HQ687567	HQ687516
Pyropia abbottiae	Harling Point, Victoria, BC, Canada	GU319835	EU223024
Pyropia acanthophora	Ubatuba, São Paulo, Brazil	L26197	HQ605695
Pyropia brumalis	Stanley Park, Vancouver, BC, Canada	GU319837	EU223038
Pyropia crassa	Nosappu, Nemuro, Hokkaido, Japan	HQ687569	HQ687518
Pyropia dentata	Suzu, Ishikawa, Japan	LC434512	LC434515
Pyropia denticulata	Mooloolaba, Queensland, Australia	HQ687570	HQ687521
Pyropia fucicola	Sitka airport, Japonski Island, AK, USA	GU319841	EU223088
Pyropia haitanensis	Yuge, Ehime, Japan	AB013181	AB118585
Pyropia hollenbergii	Agua Verde, Baja California Sur, Mexico	HQ687589	HQ687523
Pyropia ishigecola	Yoshio, Katsuura, Chiba, Japan	HQ687571	HQ687524
Pyropia katadae	Ise, Mie, Japan	HQ687572	HQ687525
Pyropia kinositae	Arito, Suttu, Hokkaido, Japan	EU521640	EU521641
Pyropia kitoi	Tokawa, Choshi, Chiba, Japan	LC328549	LC328552
Pyropia koreana	Donghae, Gangwondo, South Korea	KM067458	KM078727
Pyropia kuniedae	Sachon, Namhae, Gyeongsangnamdo, Korea	HQ728192	HQ728200
Pyropia kurogii	Sandy Beach, Sitka, AK, USA	GU319845	EU223105
Pyropia lacerata	Shirahama, Chiba, Japan	HQ687574	HQ687527
Pyropia leucosticta	Sidmouth, UK	HQ687593	HQ687528
Pyropia neodentata	Shirahama, Chiba, Japan	HQ687588	HQ687520
Pyropia pendula	Calerita, Baja California Sur, Mexico	DQ084430	HQ687530
Pyropia pseudolinearis	Otaru, Hokkaido, Japan	LC434511	LC434514
Pyropia rakiura	Ocean View, Kaikoura, South I, NZ	AF136425	EU521646
Pyropia saldanhae	Kommetjie, South Africa	AY292630	GU165838
Pyropia seriata	Hondo, Kumamoto, Japan	HQ687576	HQ687533
Pyropia smithii	Vancouver Island, BC, Canada	GU319861	EU223224
Pyropia spiralis	Vila Velha, Espírito Santo, Brazil	AY766360	HQ605696
Pyropia suborbiculata	Wonsando, Chungchungnamdo, Korea	HQ728193	HQ728201
Pyropia tanegashimensis	Iseki, Tanegashima, Kagoshima, Japan	HQ727887	HQ687542
Pyropia tenera	Kawaura, Kumamoto, Japan	AB013176	AB118576
Pyropia tenuipedalis	Urayasu, Chiba, Japan	EU521648	EU521649
Pyropia torta	Vista Mar, San Juan Island, WA, USA	GU319863	EU223236
Pyropia vietnamensis	Thangeseri, Kerala, India	HQ687578	HQ687544
Pyropia yezoensis	Galmok, Tongyoung, Gyeongsangnamdo, Korea	HQ728189	HQ728197
Wildemania amplissima	Nosappu, Nemuro, Hokkaido, Japan	HQ687585	HQ687560

For molecular phylogenetic analyses, previously published and newly determined sequence data from 38 bladed Bangiales species were used. For all taxa, sequences from two genes (nrSSU and rbcL) were obtained and included in the analyses (Table 2). The following species were selected as outgroup taxa: Wildemania amplissima (Kjellm.) Foslie, Boreophyllum pseudocrassum (Yamada & Mikami) N.Kikuchi & Miyata, Neomiuraea migitae (N.Kikuchi, S.Arai, G.Yoshida & J.-A.Shin) N.Kikuchi, S.Arai, G.Yoshida, J.-A.Shin & Miyata and Porphyra purpurea (Roth) C.Agardh. Sequence alignments for both genes were performed using ClustalX version 2.1 (Larkin et al. 2007). Intron regions in the nrSSU sequences were removed following Sutherland et al. (2011). The two gene sequences were concatenated and manually adjusted prior to phylogenetic analyses. Phylogenetic trees were constructed using two approaches: Maximum Likelihood (ML) and Bayesian Inference (BI). Before constructing the ML trees, the best-fit substitution model GTR+G+I was selected using the MEGA 12 (Kumar et al. 2024). ML trees were then generated using MEGA 12 with 1000 bootstrap replicates. For BI analyses, MrBayes v3.2.7 (Ronquist et al. 2012) was used. Two independent runs with four Markov chain Monte Carlo (MCMC) chains were conducted, each running for 100000 generations and sampling every 1000 generations. The first 25% of sampled trees were discarded as burn-in, and the remaining trees were used to calculate the Bayesian posterior probability for each clade. The resulting ML tree was visualized using MEGA 12.

Results

Field observations

Numerous mature foliose thalli of Porphyra akasakae were observed on the intertidal rocks in February 2023 at three localities of Miyagi Prefecture including the type locality (Fig. 1D, E). The foliose thalli of Po. akasakae were growing with the foliose thalli of Pyropia yezoensis (Ueda) M.S.Hwang & H.G.Choi and Py. pseudolinearis (Ueda) N.Kikuchi, Miyata, M.S.Hwang & H.G.Choi.

Fig. 1. Porphyra akasakae. A. Specimen collected from Hashikami Sanzunokawa (the type locality), Kesennuma, Miyagi, Japan on 27 February 2023 by N.Kikuchi (CMNH-BA-8501). The culture strain UM-AK1 was isolated from the female thallus. B. Specimen collected from Hajikami Iwaisaki, Kesennuma, Miyagi, Japan on 27 February 2023 by N.Kikuchi (CMHN-BA-8504). The culture strain UM-AK2 was isolated from the female thallus. C. Specimen collected from Arato Ushihama, Shizugawa Gongen, Minamisanriku, Miyagi, Japan on 28 February 2023 by N.Kikuchi (CMNH-BA-8508). The culture strain UM-AK7 was isolated from the female thallus. D. Foliose thalli on intertidal rock at Hashikami Sanzunokawa (the type locality), Kesennuma, Miyagi, Japan on 27 February 2023. Photographed by N.Kikuchi. E. Foliose thalli on intertidal rock at Hajikami Iwaisaki, Kesennuma, Miyagi, Japan on 27 February 2023. Photographed by N.Kikuchi.

Morphology

Foliose thalli of Porphyra akasakae are membranaceous and monostromatic, and the shape is oblanceolate and obovate (Fig. 1A–C). The thallus base is attenuate, obtuse and rotund, and the margin is somewhat undulate and entire (Fig. 2A). Thalli are up to 43 cm long, 3.3 cm broad, and 31–34 µm thick in central vegetative portion (Fig. 2B). Foliose thalli are greenish reddish brown to yellowish brown in color, and each cell contains a single stellate chloroplast with a central obscure pyrenoid. Vegetative cells are oblong, triangular and polygonal with rounded angles, 13–26 µm long and 10–13 µm short in surface view (Fig. 2C), and oblong, square and transversely oblong with rounded angles, 13–17 µm high and 12–20 µm broad in sectional view (Fig. 2B). Basal cells with rhizoidal filaments are capitate and 21–42 µm long and 17–24 µm short in surface view (Fig. 2D). Thalli are dioecious (Fig. 1A–C). Spermatangia are formed on the margins of the upper and middle portion of the foliose thalli. The division formula of spermatangia is up to 128(a/4, b/4, c/8) (Fig. 2E, F), and thalli are 53–59 µm thick in the spermatangial regions (Fig. 2F). Carpogonia are elliptic and lens-shaped, and 25–31 µm high and 10–17 µm broad in sectional view (Fig. 2G, H). Prototrichogynes are absent or inconspicuous (Fig. 2G, H). The division formula of zygotosporangia is up to 8(a/2, b/2, c/2) (Fig. 2I, J). Thalli are 37–42 µm thick in zygotosporangial regions (Fig. 2J).

Fig. 2. Foliose thalli of Porphyra akasakae collected from Hajikami Iwaisaki, Kesennuma, Miyagi, Japan on 27 February 2023. A. Marginal portion, showing entire margin. B. Vegetative cells in central portion of thallus in sectional view. C. Vegetative cells in central portion of thallus in surface view. D. Basal cells projecting a rhizoidal filament in surface view. E. Spermatangial portion in surface view, showing each spermatangium composed of 16 cells (a/4, b/4) in maximum (arrows). F. Spermatangial portion in sectional view, showing each spermatangium composed of eight layers (c/8) in maximum (arrow). G, H. Carpogonial portion in sectional view, showing elliptic (arrowhead) or lens-shaped (large arrows) carpogonia and spermatia attached on the surface near carpogonia (small arrows). Prototrichogynes were absent or inconspicuous. I. Zygotosporangial portion in surface view, showing each zygotosporangium composed of four cells (a/2, b/2) in maximum (arrow). J. Zygotosporangial portion in sectional view, showing each zygosporangium composed of two layers (c/2) in maximum (arrow). Scale bars: 20 µm.

Molecular phylogenetic analysis

A total of 1843 bp of the nrSSU gene (excluding introns) and 1467 bp of the rbcL gene were sequenced from three culture strains collected from Miyagi Prefecture (UM-AK1, UM-AK2 and UM-AK7) of Porphyra akasakae. The nrSSU and rbcL sequences of all three strains were identical, including intron regions in nrSSU. Therefore, only one concatenated sequence of the species was used for the phylogenetic analysis.

A total of 38 concatenated sequences were analyzed to construct the phylogenetic tree shown in Fig. 3. Both maximum likelihood (ML) and Bayesian inference (BI) analyses produced similar tree topologies; therefore, only the ML tree is presented (Fig. 3). The resulting tree was consistent with the topology previously reported by Sutherland et al. (2011). The phylogenetic tree clearly resolved the Porphyra akasakae strains from Miyagi Prefecture as forming a clade with Pyropia tenera (Kjellm.) N.Kikuchi, Miyata, M.S.Hwang & H.G.Choi, Py. yezoensis and Py. ishigecola (A.Miura) N.Kikuchi & Miyata.

Fig. 3. Maximum likelihood (ML) phylogenetic tree inferred from the concatenated nrSSU and rbcL dataset. Each branch shows two support values: ML bootstrap probability/Bayesian posterior probability. Some values less than 50% ML / 0.5 Bayesian probability were omitted for clarity.

Discussion

Porphyra akasakae was described by Miura (1977) as a new species based on the foliose thalli attached on Nori cultivation nets along the coast of Sanriku, Tohoku Region, northern Japan. No molecular sequence data have been available previously for this species. We collected the foliose thalli of the species at three localities including the type locality designated by Miura (1977), and conducted morphological observations and molecular phylogenetic analysis.

The morphology of the foliose thalli of Porphyra akasakae is consistent with the observations of Miura (1977). In the phylogenetic tree based on the nrSSU and the rbcL genes showed that Po. akasakae clearly belongs to the genus Pyropia, and is a closely related to three species, Py. ishigecola, Py. tenera and Py. yezoensis (bootstrap value 84% and posterior probability 1; Fig. 3). Although we could not include Po. oligospermatangia C.K.Tseng & B.F.Zheng in the phylogenetic analysis due to a lack of nrSSU sequences, the rbcL sequence (accession number: GQ427226) is available. In the rbcL sequence, differentiation between Po. akasakae and Py. ishigecola is 0.81%, followed by Py. tenera (1.02%), Po. oligospermatangia (1.07%) and Py. yezoensis (1.09%), which is comparable to the intraspecific differentiation of the rbcL sequence reported in Bangiales (from 0% to 1%, up to 2% in some taxa) (Lindstrom and Fredericq 2003, Lindstrom 2008, Nelson and Broom 2010, Kucera and Saunders 2012, Mols-Mortensen et al. 2012, Vergés et al. 2013). This suggests that Po. akasakae and the other four species are very close.

On the other hand, there is a clear difference in sexuality between Porphyra akasakae and the other closely related four species: Pyropia ishigecola, Py. tenera, Py. yezoensis and Po. oligospermatangia have monoecious foliose thalli and the spermatangia and zygotosporangia are intermixed on the thalli (Kurogi 1961, Miura 1967, Zheng 1981, Kikuchi 2020), while Po. akasakae is basically dioecious and rarely monoecious, divided into male and female portions (Miura 1977, Kamiya et al. 2008). We only found dioecious thalli in this study. Therefore, Po. akasakae is morphologically distinct from the other four close species.

Based on the sequence data presented here as well as morphological features we conclude that Porphyra akasakae requires recognition as an independent species in the genus Pyropia.

Pyropia akasakae (A.Miura) N.Kikuchi, Shot.Suzuki, Tamaki & Ta.Abe, comb. nov.

Porphyra akasakae A.Miura in J. Tokyo Univ. Fish. 63: 197 (1977). Holotype: JAPAN. Miyagi Pref., Kesennuma, Hashikami Sanzunokawa, 12 December 1968, A.Miura (Miura 2294, Herbarium of Miura, Tokyo University of Marine Science and Technology [Fig. 4]).

Fig. 4. Holotype of Pyropia akasakae (A.Miura) N.Kikuchi, Shot.Suzuki, Tamaki & Ta.Abe (Miura 2294, Herbarium of Miura, Tokyo University of Marine Science and Technology).

Acknowledgments

We are grateful to Dr. W. A. Nelson, for her valuable comments on the manuscript and correcting the English. We also thank Miyagi Prefecture Fisheries Technology Institute, Miyagi Fisheries Cooperative Association, Minamisanriku Nature Center and Mr. A. Hatakeyama for collection of materials.

References

•  Abe  M.,  Kikuchi  N.,  Tamaki  M.,  Sato  T.,  Murase  N.,  Fujiyoshi  E. and  Kobayashi  M. 2021. Neoporphyra kitoi sp. nov. (Bangiales, Rhodophyta) from Japan, with new blades arising from rhizoidal cells. Phycol. Res. 69: 237–245. doi: 10.1111/pre.12464.
•  Broom  J.E.,  Jones  W.A.,  Hill  D.F.,  Knight  G.A. and  Nelson  W.A. 1999. Species recognition in New Zealand Porphyra using 18S rDNA sequencing. J. Appl. Phycol. 11: 421–428. doi: 10.1023/A:1008162825908.
•  Fujiyoshi  E. and  Kikuchi  N. 2006. Growth of excised pieces containing elongated denticles from the lower marginal parts of Porphyra tanegashimensis and P. haitanensis gametophytes. Bull. Fish. Res. Agen. 16: 9–13.
•  Hara  K. 1948. Byochugai-Hoten. [Manual of Pests and Diseases]. Yokendo, Tokyo (in Japanese).
•  Hillis  D.M. and  Dixon  M.T. 1991. Ribosomal DNA: Molecular evolution and phylogenetic inference. Q. Rev. Biol. 66: 411–453.
•  Hommersand  M.H.,  Fredericq  S. and  Freshwater  D.W. 1994. Phylogenetic systematics and biogeography of the genus Gigartinaceae (Gigartinales, Rhodophyta) based on sequence analysis of rbcL. Bot. Mar. 37: 193–203. doi: 10.1515/botm.1994.37.3.193.
•  Kamiya  A.,  Maeda  T. and  Notoya  M. 2008. Morphological studies of Porphyra akasakae Miura (Rhodophyta, Bangiales) from Iwaizaki, Miyagi Prefecture, Japan and its physiological responses, and the life cycle in laboratory culture. Algal Resources 1: 17–24 (in Japanese).
• Kikuchi N. 2020. [Morphology and taxonomy]. In:  Niwa  K. (ed.), [Science of Nori]. Pp. 32–61. Asakura Publishing, Tokyo (in Japanese).
•  Kikuchi  N.,  Arai  S.,  Yoshida  G.,  Shin  J.-A. and  Miyata  M. 2018. Neomiuraea nom. nov., a replacement name for Miuraea N.Kikuchi, S.Arai, G.Yoshida, J.-A.Shin & Miyata (Bangiales, Rhodophyta), nom. illeg. Notulae Algarum 62: 1.
•  Kucera  H. and  Saunders  G.W. 2012. A survey of Bangiales (Rhodophyta) based on multiple molecular markers reveals cryptic diversity. J. Phycol. 48: 869–882. doi: 10.1111/j.1529-8817.2012.01193.x.
•  Kumar  S.,  Stecher  G.,  Li  M.,  Knyaz  C. and  Tamura  K. 2018. MEGA X: molecular evolutionary genetics analysis across computing platforms. Mol. Biol. Evol. 35: 1547–1549. doi: 10.1093/molbev/msy096.
•  Kumar  S.,  Stecher  G.,  Suleski  M.,  Sanderford  M.,  Sharma  S. and  Tamura  K. 2024. MEGA12: molecular evolutionary genetic analysis version 12 for adaptive and green computing. Mol. Biol. Evol. 41: msae263. doi: 10.1093/molbev/msae263.
•  Kurogi  M 1961. Species of cultivated Porphyras and their life histories. Bull. Tohoku Reg. Fish. Res. Lab. 18: 1–115.
•  Larkin  M.A.,  Blackshields  G.,  Brown  N.P.,  Chenna  R.,  McGettigan  P.A.,  McWilliam  H.,  Valentin  F.,  Wallace  I.M.,  Wilm  A.,  Lopez  R.,  Thompson  J.D.,  Gibson  T.J. and  Higgins  D.G. 2007. Clustal W and Clustal X version 2.0. Bioinformatics 23: 2947–2948. doi: 10.1093/bioinformatics/btm404.
•  Li  Y.-L.,  Wang  J.,  Pu  J.-Q.,  Hu  C.-M.,  Zhou  W.,  Brodie  J. and  Yang  L.-E. 2025. History and advances in the taxonomy of the Bangiaceae (Rhodophyta) and new evidence to support splitting the genus Pyropia. Eur. J. Phycol. 60: 288–304. doi: 10.1080/09670262.2025.2493837.
•  Lindstrom  S.C. 2008. Cryptic diversity, biogeography and genetic variation in Northeast Pacific species of Porphyra sensu lato (Bangiales, Rhodophyta). J. Appl. Phycol. 20: 951–962. doi: 10.1007/s10811-008-9313-9.
•  Lindstrom  S.C. and  Fredericq  S. 2003. rbcL gene sequences reveal relationships among north-east Pacific species of Porphyra (Bangiales, Rhodophyta) and a new species, P. aestivalis. Phycol. Res. 51: 211–224.
•  Matsushita  S.,  Takahashi  N.,  Okamoto  M.,  Tamaki  M.,  Kikuchi  N.,  Kobiyama  A. and  Niwa  K. 2025. Hidden diversity of Pyropia dentata complex (Bangiales, Rhodophyta) in Japan, with description of a new species Pyropia neodentata from the Pacific coast of Japan. Phycol. Res. 73: 168–181.
•  Miura  A. 1967. Two new species and a new record of Porphyra from Enoshima, Sagami Bay. J. Tokyo Univ. Fish. 53(1–2): 65–71.
•  Miura  A. 1977. Porphyra akasakai, a new species from the Sanriku coast, northeastern district of Honshu, Japan. J. Tokyo Univ. Fish. 63(2): 197–202.
•  Mols-Mortensen  A.,  Neefus  C.D.,  Nielsen  R.,  Gunnarsson  K.,  Egilsdóttir  S.,  Møller Pedersen  P. and  Brodie  J. 2012. New insights into the biodiversity and generic relationships of foliose Bangiales (Rhodophyta) in Iceland and the Faroe Islands. Eur. J. Phycol. 47: 146–159. doi: 10.1080/09670262.2012.666678.
•  Nelson  W.A. and  Broom  J.E.S. 2010. The identity of Porphyra columbina (Bangiales, Rhodophyta) originally described from the New Zealand subantarctic islands. Aust. Syst. Bot. 23: 16–26. doi: 10.1071/SB09032.
•  Nishina  H.,  Miyazaki  K.,  Horinouchi  Y. and  Niwa  K. 2025. Taxonomic revision of Pyropia kurogii (Bangiales, Rhodophyta) in Japan, including the description of Pyropia ezokurogii sp. nov., its early development pattern and the sex ratio of the gametophytic blades. Phycologia 64: 394–403. doi: 10.1080/00318884.2025.2547463.
•  Ronquist  F.,  Teslenko  M.,  van der Mark  P.,  Ayres  D.L.,  Darling  A.,  Hohna  S.,  Larget  B.,  Liu  L.,  Suchard  M.A. and  Huelsenbeck  J.P. 2012. MrBayes 3.2: Efficient Bayesian phylogenetic inference and model choice across a large model space. Syst. Biol. 61: 539–542. doi: 10.1093/sysbio/sys029.
•  Sánchez  N.,  Vergés  A.,  Peteiro  C.,  Sutherland  J.E. and  Brodie  J. 2014. Diversity of bladed Bangiales (Rhodophyta) in western Mediterranean: recognition of the genus Themis and descriptions of T. ballesterosii sp. nov., T. iberica sp. nov., and Pyropia parva sp. nov. J. Phycol. 50: 908–929. doi: 10.1111/jpy.12223.
•  Sano  F.,  Ikeura  A.,  Takasugi  A. and  Niwa  K. 2021. First record of Neoporphyra haitanensis (T.J.Chang & B.F.Zheng) J.Brodie & L.-E.Yang (Bangiales, Rhodophyta) from Shikinejima Island and Hachijojima Island of the Izu Islands, southern central Japan. Phycol. Res. 69: 258–265. doi: 10.1111/pre.12466.
•  Saunders  G.W. and  Kraft  G.T. 1994. Small-subunit rRNA gene sequences from representatives of selected families of the Gigartinales and Rhodymeniales (Rhodophyta). 1. Evidence for the Plocamiales ord. nov. Can. J. Bot. 72: 1250–1263. doi: 10.1139/b94-153.
•  Simon  L.,  Lalonde  M. and  Bruns  T.D. 1992. Specific amplification of 18S fungal ribosomal genes from vesicular-arbuscular endomycorrhizal fungi colonizing roots. Appl. Environ. Microbiol. 58: 291–295. doi: 10.1128/aem.58.1.291-295.1992.
•  Sutherland  J.E.,  Lindstrom  S.C.,  Nelson  W.A.,  Brodie  J.,  Lynch  M.D.J.,  Hwang  M.S.,  Choi  H.-G.,  Miyata  M.,  Kikuchi  N.,  Oliveira  M.C.,  Farr  T.,  Neefus  C.,  Mols-Mortensen  A.,  Milstein  D. and  Müller  K.M. 2011. A new look at an ancient order: generic revision of the Bangiales (Rhodophyta). J. Phycol. 47: 1131–1151. doi: 10.1111/j.1529-8817.2011.01052.x.
•  Tamaki  M.,  Fujita  Y.,  Fujiyoshi  E.,  Kobayashi  M.,  Abe  M.,  Kikuchi  N. and  Sudo  Y. 2012. Morphological and molecular analysis of Porphyra yamadae collected at Ginowan, Okinawajima Island. Biol. Mag. Okinawa 50: 1–15 (in Japanese).
•  Tamaki  M.,  Fujiyoshi  E.,  Abe  M.,  Kobayashi  M.,  Matsuoka  S.,  Hamatake  Y.,  Yamashita  H.,  Ito  R. and  Hara  T. 2020. DNA analysis of rare species of laver, Pyropia kuniedae and Pyropia seriata (Bangiales, Rhodophyta) from Japan. DNA Polymorphism 28: 9–15 (in Japanese).
•  Tamaki  M.,  Fujiyoshi  E.,  Fujita  Y.,  Kobayashi  M.,  Kikuchi  N. and  Hagiwara  A. 2018. Genetic characteristics of Porphyra yamadae (Bangiales, Rhodophyta) in Japan. DNA Polymorphism 26: 6–12.
•  Taruta  M.,  Kurogi  T. and  Kito  H. 2007. Determination of phylogenic relationships between several Porphyra species utilizing novel methodologies of SSUrRNA and RuBisCO gene analysis. Nori-to-Kaiso 73: 1–42 (in Japanese).
•  Thomas  V.,  Herrera-Rimann  K.,  Blanc  D.S. and  Greub  G. 2006. Biodiversity of amoebae and amoeba-resisting bacteria in a hospital water network. Appl. Environ. Microbiol. 72: 2428–2438. doi: 10.1128/AEM.72.4.2428-2438.2006.
•  Vergés  A.,  Comalada  N.,  Sánchez  N. and  Brodie  J. 2013. A reassessment of the foliose Bangiales (Rhodophyta) in the Balearic Islands including the proposed synonymy of Pyropia olivii with Pyropia koreana. Bot. Mar. 56: 229–240. doi: 10.1515/bot-2013-0003.
• White T.J., Bruns T., Lee S., Tayler J., Innis M., Gelfand D. and Sninsky J. 1990. Amplification and direct sequencing of fungal ribosomal RNA genes for phylogenetics. In:  Innis  M.A.,  Gelfand  D.H.,  Sninsky  J.J. and  White  T.J. (eds.), PCR Protocols: A Guide to Methods and Applications. Pp. 315–322. Academic Press, San Diego.
•  Xie  Z.-Y.,  Lin  S.-M.,  Liu  L.-C.,  Ang  Jr. P.O. and  Shyu  J.-F. 2015. Genetic diversity and taxonomy of foliose Bangiales (Rhodophyta) from Taiwan based on rbcL and cox1 sequences. Bot. Mar. 58: 189–202. doi: 10.1515/bot-2014-0063.
•  Yang  L.-E.,  Deng  Y.-Y.,  Xu  G.-P.,  Russell  S.,  Lu  Q.-Q. and  Brodie  J. 2020. Redefining Pyropia (Bangiales, Rhodophyta): four new genera, resurrection of Porphyrella and description of Calidia pseudolobata sp. nov. from China. J. Phycol. 56: 862–879. doi: 10.1111/jpy.12992.
•  Zheng  B.F. 1981. Porphyra oligospermatangia, a new species of Porphyra. Oceanologia et Limnologia Sinica 12(5): 447–451.
•  Zuccarello  G.C.,  Wen  X. and  Kim  G.H. 2022. Splitting blades: why genera need to be more carefully defined; the case for Pyropia (Bangiales, Rhodophyta). Algae 37: 205–211. doi: 10.4490/algae.2022.37.9.11.