Peyssonneliales is a monotypic order of red algae belonging to the class Florideophyceae and the subclass Rhodymeniophycidae.Kamiya, M., Lindstrom, S.C., Nakayama, T., Yokoyama, A., Lin, S.-M., Guiry, M.D., Gurgel, F.D.G., Huisman, J.M., Kitayama, T., Suzuki, M., Cho, T.O. & Frey, W. 2017. Rhodophyta. In: Syllabus of Plant Families, 13th ed. Part 2/2: Photoautotrophic eukaryotic Algae. (Frey, W. Eds), pp. [i]–xii, –171. Stuttgart: Borntraeger Science Publishers It contains only one known family, Peyssonneliaceae .Denizot, M., 1968. Les algues floridées encroutantes (à l'éxclusion des Corallinacées). pp. –310, 227 figs. Paris: Laboratoire de Cryptogamie, Muséum National d'Histoire Naturelle. Reference page. : 86, 308.

The type species is Peyssonnelia .

History Genera Peyssonnelia and Sonderopelta were originally in order Gigartinales but comparative morphology and rbcL and nuclear LSU rRNA sequence data showed that they were separate and therefore order Peyssonneliales was established in 2009 to hold them both.

Incendia was initially resolved as a monophyletic clade with full support for rbcL. Then using robust rbcL phylogeny, order Peyssonneliales was lso resolved as monophyletic with well-supported main lineages.

Description Delineation of the various genera in the Peyssonneliaceae had mostly been based on vegetative characteristics.

Peyssonneliales order algae are red, crustose, prostrate, and usually epilithic (growing on the surfaces of rocks). The crusts may be non-calcified throughout, calcified throughout, or partially calcified (with hypobasal calcification (situated posterior to the basal wall) between the attachment rhizoids). Calcium carbonate, if present, is in the mineral form aragonite (James et al., 1988). The lower surfaces of the crusts are partially to completely attached to the sub-stratum, either directly (i.e., without rhizoids) or by unicellular or multi cellular rhizoids. Prostrate growth is by radiating marginal rows of transversely dividing apical initials in the basal layer (multi axial). These growths then later divide vertically to form a single upper or lower perithallial cell (surrounding the thallus). The first section of the perithallial cells gives rise to simple or branched filaments that together form a loose to compact upper- only cortex or upper and lower cortices. Cortical cells have numerous discoid or ribbon- like chloroplasts.

The red algae colour comes from photosynthetic pigments (phycoerythrin, phycocyanin, allophycocyanin). Then the various blends of relative amounts of these 3 and chlorophyll, influences the plant colour, which can vary from dark red to blue, brown, or greenish.

Genera As accepted by AlgaeBase (with number of species per genera);

Agissea - 14 spp. Brasilophycus - 2 spp. Chevaliericrusta - 1 sp. Cruoriella - 4 spp. Cruoriopsis - 4 spp. Incendia - 10 spp. Metapeyssonnelia - 5 spp. Olokunia - 5 spp. Peyssonnelia - 68 spp. Piriora - 1 sp. Polystrata - 6 spp. Pulvinia - 1 sp. Ramicrusta - 19 spp. Rhodowynnea - 3 spp. Riquetophycus - 1 sp. Seiria - 2 spp. Sonderophycus - 4 spp. Squamaria - 1 sp.

Former genera; Gymnosorus , Haematostagon , Lithymenia , Nardoa and Sonderopelta

WoRMS doesn't accept the genera; Agissea, Brasilophycus, Olokunia, Piriora, Rhodowynnea and Squamaria. It also notes; Cruoriopsis is accepted as synonym of Peyssonnelia, Haematostagon is accepted as synonym of Peyssonnelia, Lithymenia is accepted as synonym of Peyssonnelia Sonderopelta is accepted as synonym of Sonderophycus.

Distribution The order has cosmopolitan distribution, worldwide. They are found in places such as Brazil, western Atlantic Ocean,Yossi Loya, Kimberly A. Puglise and Tom C.L. Bridge (Editors) San Andres Island, (in the Caribbean Sea),Santiago Herrera, Juan Armando Sanchez and Luisa Fernanda Dueñas (Editors) Jamaica (also in the Caribbean Sea), Puerto Rico, Gulf of California (Pacific Ocean), Hawaii,Sherwood, A.R., Paiano, M.O., Spalding, H.L. & Kosaki, R.K. (2020) Biodiversity of Hawaiian Peyssonneliales (Rhodophyta). 2. Sonderophycus copusii, a new species from the Northwestern Hawaiian Islands. ALGAE 35: 145–155. https://doi.org/10.4490/algae.2020.35.5.20 Azores (Atlantic Ocean), Brittany in France,Christian Wiencke (Editor) southern Australia, New Zealand, also parts of Asia (near Indonesia, Thailand, South Korea and China).Antoninovich Eduard Titlyanov, Viktorovna Tamara Titlyanova, Xiubao Li and Hui Huang

They can grow at low depths, from the Intertidal zone, (between in western Atlantic Ocean), or down to depths as low as below sea level in the Pacific Ocean (near California).

Members of Peyssonneliales can be found growing on hard substratum (bedrock), or found growing on corals.

Uses Peyssonnelia has anti-viral abilities.Maria Hayes (Editor)

Ecology Peyssonneliaceae make thick, brown/dark red growths that may have a soft top above a hard base. Fish do not eat it, allowing it to grow and smother corals. Peyssonneliaceae also keep coral from successfully reproducing sexually by preventing coral larvae from settling.

References

Other sources Ballantine, D. L., Lozada-Troche, C. & Ruíz, H. 2014. Metapeyssonnelia tangerina (Peyssonneliaceae, Rhodophyta), a new species associated with coral reef habitats in Puerto Rico, Caribbean Sea. Phycol. Res. 62:197-205. Ballantine, D. L. & Ruiz, H. 2005. Two Peyssonnelia species (Peyssonneliaceae, Rhodophyta) from Puerto Rico including Peyssonnelia flavescens sp. nov. Phycologia 44:328-34. Bassi, D., 1997. Vegetative anatomy and palaeoecology of Polystrata alba (Pfender) Denizot, 1968 (Cryptonemiales, Peyssonneliaceae) (Late Eocene, Northern Italy). Revue de Paléobiologie 16 (2):309-320. Dixon, K.R. & Saunders, G.W., 2013. DNA barcoding and phylogenetics of Ramicrusta and Incendia gen. nov., two early diverging lineages of the Peyssonneliaceae (Rhodophyta). Phycologia 52: 82–108. DNA barcoding and phylogenetics of Ramicrusta and Incendia gen. nov., two early diverging lineages of the Peyssonneliaceae (Rhodophyta) Sherwood, A.R., Paiano, M.O., Spalding, H.L. & Kosaki, R.K. 2020. Biodiversity of Hawaiian Peyssonneliales (Rhodophyta). 2. Sonderophycus copusii, a new species from the Northwestern Hawaiian Islands. ALGAE 35: 145–155. Biodiversity of Hawaiian Peyssonneliales (Rhodophyta): Sonderophycus copusii sp. nov., a new species from the Northwestern Hawaiian Islands