Talk:Epithemia

All species in the genus Rhopalodia have been subsumed into Epithemia per Ruck et al. 2016, but not all people agree with this. I think it would be useful to denote which taxa in the species list were "once" Rhopalodia (and may be returned to Rhopalodia depending on where taxonomists settle over the next few years). Cyanochic (talk) 18:10, 16 September 2024 (UTC)

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I'd like to propose a relatively minor rewording of the first sentence in the [Relatives] section and some notes on relatively pedantic accuracy. I will not add any edits to this page as I have COI. (Full transparency: I am first author on paper 1 referenced below.)

The sentence currently reads as: "The closest relatives of the SBs are various members of the (overly broad, since divided)[13] genus Cyanothece, especially strain ATCC 51142."

I'd like to suggest rewording to something akin to: "The closest relatives of the SBs are within the family Aphanothecaceae." And then bring the last sentence of the 2nd paragraph to immediately follow. ("The closest named to the SBs is Rippkaea orientalis.")

My reasoning for suggesting this change: No close relatives to the endosymbionts are within the genus Cyanothece anymore. (As the article currently mentions, it has been heavily split.) Rippkaea is the closest named free-living genus later mentioned in the paragraph (specifically Rippkaea orientalis PCC 8801). The other strain mentioned (ATCC 51142) is now within the genus Crocosphaera. For what it's worth, that strain is much more closely related to the nitroplast mentioned than these endosymbionts.

If whoever edits this would like to retain more detail or look into it more: A whole genome phylogeny of endosymbionts places the symbionts most closely related to Rippkaea orientalis PCC 8801 (and an unnamed unicellular cyanobacterium SU2). 1 Past single gene phylogenies (nifH or 16S) do place the Rhopalodiaceae endosymbionts near Cr. subtropica ATCC 51142. References already in the page are available for this: Schvarcz et al (currently ref 2) and Nakayama et al. 2011 (currently ref 7)

Two pedantic accuracy notes:

• "The diazoplasts have no photosynthetic genes at all." is not completely accurate. In the paper currently referenced there, they show that the endosymbiont has lost nearly all genes for photosynthesis, but not ALL. (Fig 3 shows PS related genes in blue.)
• "Based on fossil records, the symbiosis happened in a common ancestor of species that carry it about 35 million years ago." Should be "at least 35 million years ago". The current day species are in the fossil record going back at least 35 million years ago, as in "not more recently than 35 million years ago". There aren't currently any studies improving or making a more accurate estimate.

Cyanochic (talk) 04:05, 22 January 2026 (UTC)