Pyrenomonadaceae is a family of

cryptomonads The cryptomonads (or cryptophytes) are a superclass of algae, most of which have plastids. They are traditionally considered a division of algae among phycologists, under the name of Cryptophyta. They are common in freshwater, and also occur ...

which includes three or four known genera. They are distinguished from other cryptomonads by their

nucleomorphs Nucleomorphs are small, vestigial eukaryotic nuclei found between the inner and outer pairs of membranes in certain plastids. They are thought to be vestiges of red and green algal nuclei that were engulfed by a larger eukaryote. Because the nucl ...

being imbedded into the

pyrenoid Pyrenoids are sub-cellular phase-separated micro-compartments found in chloroplasts of many algae,Giordano, M., Beardall, J., & Raven, J. A. (2005). CO2 concentrating mechanisms in algae: mechanisms, environmental modulation, and evolution. ''An ...

, and the presence of distinctive pigment

phycoerythrin Phycoerythrin (PE) is a red protein-pigment complex from the light-harvesting phycobiliprotein family, present in cyanobacteria, red algae and Cryptomonad, cryptophytes, accessory to the main chlorophyll pigments responsible for photosynthesis.The ...

545.

Taxonomy

Rhodomonas ''Rhodomonas'' is a genus of cryptomonads. It is characterized by its red colour, the square-shaped plates of its inner periplast, its short furrow ending in a gullet, and a distinctly shaped chloroplast A chloroplast () is a type of memb ...

'' was the first genus within today's Pyrenomonadaceae identified, being described in 1898. For most of the 20th century, all other genera now recognized as ''Pyrenomonadaceae'' were placed into various other taxa (ex. ''Rhinomonas fulva'' as ''Cryptochrysis fulva'')

Adolf Pascher Adolf Alois Pascher (31 May 1881 – 7 May 1945) was a Bohemian botanist and phycologist, notable for his descriptions of several new genera of algae, protists, and vascular plants. Biography Born in Stožec, Pascher was the son of a teacher, ...

placed

within his subfamily Cryptochrysideae in 1913. Butcher's highly influential 1967 phylogeny of all then-known Cryptophytes did not recognize ''Rhodomonas'', reclassifying all previously described Rhodomonas species as ''

Chroomonas ''Chroomonas'' is a genus of cryptophytes first described by Anton Hansgirg. It includes the species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can ...

''. Between 1982 and 1986, a series of

ultrastructure Ultrastructure (or ultra-structure) is the architecture of cells and biomaterials that is visible at higher magnifications than found on a standard optical light microscope. This traditionally meant the resolution and magnification range of a c ...

studies by Uwe J. Santore found considerable morphological inconsistencies within Butcher's ''Chroomonas'', leading him to identify the new genus

Pyrenomonas ''Pyrenomonas'' is a genus of cryptomonad.Guiry, M.D. & Guiry, G.M. (2018). AlgaeBase. World-wide electronic publication, National University of Ireland, Galway (taxonomic information republished from AlgaeBase with permission of M.D. Guiry). Pyr ...

in 1984. Two years later, he revived genus ''Rhodomonas'' and proposed the existence of a clade largely consisting of "reddish-brown cryptomonads". Expanding upon Santore's research, in 1988 D.R.A. Hill and R. Wetherbee analyzed various cryptomonads that had been treated as ''

Cryptochrysis Cryptochrysis is a formerly recognized genus of cryptomonads first proposed by Adolf Pascher in 1911. He initially treated it as the sole genus in family ''Cryptochrysidaceae'', but later treated it as a member of the ''Cryptochrysideae'' subfami ...

'' by early 20th century researchers. From this they identified several new species of ''Rhodomonas'', and introduced the new genus ''

Rhinomonas ''Rhinomonas'' is a genus of cryptophytes. It includes the species ''Rhinomonas pauca''. References Cryptista genera {{Cryptomonad-stub ...

''. Hill would identify another "reddish-brown cryptomonad" genus in 1991, '' Storeatula''. In 1989, Hill and Wetherbee argued that ''Rhodomonas'' was synonymous with ''Pyrenomonas'', triggering an academic debate regarding whether or not each genus should be treated separately. This debate remains unresolved as of 2019. The earliest reference to ''Pyrenomonadaceae'' in an approximately modern sense was made by Gianfranco Novarino and Ian Lucas in their 1993 classification scheme for the

Cryptophyceae The cryptophyceae are a class of algae, most of which have plastids. About 230 species are known, and they are common in freshwater, and also occur in marine and brackish habitats. Each cell is around 10–50 μm in size and flattened in shape ...

. In this classification scheme, the family included ''Rhinomonas'' and ''Pyrenomonas''. An updated scheme in 1999 added ''Storeatula'' as well. Overall monophyly of the ''Pyrenomonadaceae'' has been universally supported by electron-microscope and molecular-based studies in the 1990s and 2000s. A 2002 phylogenic study of 18s rDNA suggested that, while the family itself was monophyletic, ''Rhodomonas'' was not, with '' R. abbreviata'' forming a clade with ''Storeatula'' while all other ''Rhodomonas'' species examined formed a clade with ''Rhinomonas''. A more comprehensive phylogenetic study in 2014 largely agreed with and expanded upon earlier findings, presenting a preliminary classification scheme with three unnamed clades.

Taxonomy

Clay et al, 1999

Deane et al, 2002

Majaneva et al, 2014

References