[Taxacom] type species for a genus - lectotype?

[Karolina Fucikova]

Hello all,
I am working on a monograph of the algal genus Bracteacoccus and I have come
across a problem with the type species, B. aggregatus. I am hoping someone
here could give me some suggestions.
OK, here goes: The holotype for B. aggregatus is a figure and not a very
informative one. The circumscription has some usable info but not a lot. The
generic diagnosis of Bracteacoccus was emended by Starr in 1955. By then,
the live material (culture) associated with B. aggregatus was not available
(presumably lost or dead), and Starr based his emendation on another
species, B. minor. Since then, phycologists have been using Starr's concept
of Bracteacoccus, and several other species of Bracteacoccus have been
described since.
Now, I have molecular data for most Bracteacoccus species (based on type
cultures), but the most important one is obviously missing - B. aggregatus.
Not only is there no type material available - there are virtually no
cultures of B. aggregatus available at all. It's almost like nobody has seen
that species since its description in 1923. No wonder, too - with the vague
species description. What can I do about the type for the genus then? I have
heard of epitypes - I suppose I could pick a Bracteacoccus isolate that
roughly matches the original description and call it aggregatus, right? But
does that make sense when the genus name as we use it today is tied to
characteristics of a different species, B. minor? Is it acceptable for B.
minor to be designated a lectotype for the genus? We don't even know if the
original B. aggregatus had the characteristics that are now considered
diagnostic for Bracteacoccus (i.e., unequal flagellar length in zoospores).
My personal feeling is that it doesn't make sense to impose the name
aggregatus on something that may not even be close to the original material
(we'll never know). But in order to keep the name Bracteacoccus, which is
commonly used and understood, can we just leave aggregatus behind and select
a new type for the genus?
Sorry about the lengthy nature of this post - hope someone can help, or
perhaps refer me to a previous thread on a similar topic.
Many thanks!

-- 
Karolina Fucikova
PhD Candidate
Department of Ecology and Evolutionary Biology, University of Connecticut