Posted: Feb 12 2012
Rissoina angeli Espinosa & Ortea, 2002, R. striatocostata (d'Orbigny, 1842) Page 2 of 2
This is a very long and complicated presentation with multiple galleries. Be sure to scroll down and see it all.
Some more correspondence regarding R. angeli:
2012/2/26. Marlo :
"Hi Emilio,
I have a poor photo copy of E&O’s paper with a very poor image of their R. angeli, Do you have any images of their type material. If not, how confident are you that Raúl’s material is indeed the same shell?"
2/26/2012. Emilio:
"I have the issue of Avicennia with the desciption of R. angeli. Unfortunatly Espinosa & Ortea didnot use SEM photographs, so, the photo is not enough to consider which species is. Raúl saw the type material and he find the shell which sent me and he thought that it was the same species. But the most sure is to ask for the loan of the paratype in the Tenerife Museum.
To contact with Espinosa or Ortea is not useful because they only had two shells when the description was made and not more later."
3/8/2012. This date Emilio provided his interpretation of the data we've compliled and presented it with several other species under the heading "The Rissoina species with planktotrophic* development in the Caribbean and close areas."
*larvae dispersed into the water and generally spend a fairly long period suspended and feeding in the water column."
Emilio commented: "I have thought about the problem of the Rissoina species and, after the examination the important material from Marien Faber, I have goten the following conclusions which I am sending you for study and discussion: the taxa are in older order, and this is only a scheme." "I have focussed the problem only in the planktotrophic species." "I have also one group of photographs from Marlo which must be placed in a name. But I prefer to wait for the R. angeli paratype."
Rissoina elegantissima (d’Orbigny, 1842) - (It may be Schwartziella)
Rissoina bermudezi (Aguayo & Rehder, 1949) - Not problem
Rolán, E. & Fernández-Garcés, R. Dec 2010. The shouldered species of the Rissoininae (Mollusca: Rissooidea) in the Caribbean with the description of three new species. Novapex 11(4): 83-91.
3/8/2012. Upon review of Emilio's scheme Harry asked:
"Dear Emilio,
Very interesting and well-done approach." "What happened to R. cancellina?"
8 Mar 2012. Emilio replied:
"R. cancellina has only two whorls of protoconch, anyway, I have add it to the scheme (added above). Lesser than 2 probably are of direct development.
There are more Rissoinidae with multispiral protoconch, as bryerea, floridana, catesbyana, chesneli, for example, but these may be Schwartziella species. The taxon Rissoina sigmifer Mörch, 1876: do you have any information about?"
3/8/2012 . Regarding Rissoina sigmifer Mörch, 1876, Harry replied:
"The protoconch of Rissoina sigmifer is depicted by Colin (2001: pl. 16), and I have shells from:
Palm Beach Co., FL
Bahamas (3): GBI, GBI, New Providence
Honduras.
Several of these have well-preserved protoconchs: 1.5 whorls using the Pilsbry method (which produces the highest whorl count of the three techniques). Interestingly, the nucleus is quite small. It would make a nice SEM, but for the present project, this species can be ruled out."
3/8/2012. Harry commented further:
"With respect to this very useful production, I see a couple of things that might be resolved in short order:
(1) Method of whorl-counting. The issue is where the first whorl ends; there are three choices in the literature.
(2) Do I have R. cancellina correctly depicted at http://www.jaxshells.org/88ff11.htm?
(3) If it better serves our purpose, you could remove certain other species from consideration by, for example, placing R. elegantissima d'Orbigny, 1842 in Ailinzebina Ladd, 1966; R. bermudezi in Folinia; maybe even putting the reticulate taxa in Phosinella."
3/8/2012. Marien brought it up,
"one thing I would like to address separately (before even opening Emilio's ms), is whorl count. My humble opinion is that ALL counting methods are wrong. The thing to do, I think, is count from the end. If you draw a straight line up you can count the whole whorls. Any accuracy beyond that is questionable. It seems fair (to me) to list a half whorl, perhaps even a quarter whorl, but anything more "precise" (as, .e.g., stated by Verduin, who used tenths of a whorl several of his Basteria papers) is just nonsense."
There then followed several emails regarding counting protoconch whorls, which are presented at Counting Protoconch Whorls.
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