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I'm trying to understand the relationship of plants formerly classified as Dorstenia crispa with distinct individuals continuously classified as Dorstenia foetida. I would assume that the distinctive phenotype would warrant a var. or forma, if not a subspecies, but I haven't seen it written as such anywhere.

I turned to monographs, which in one case stated:

incl. Dorstenia crispa Engler (1898); ... incl. Dorstenia crispa var. lancifolia Rendle (1915) ≡ Dorstenia foetida ssp. lancifolia (Rendle) Friis (1983);

  1. Would this indicate that a specimen identified as D. crispa is properly identified no more specifically than as D. foetida?
  2. Does this indicate that a specimen of D. crispa v. lancifolia is properly D. foetida ssp. lancifolia; or simply recognising that D. crispa v. lancifolia and D. foetida ssp. lancifolia would refer to the same individuals, which are properly still called nothing more than D. foetida?
  3. Since these formerly-recognised infraspecific taxa do exist as separately-kept lines in cultivation, would they be properly recognised as cultivars?

My answer may simply be the closing remark in the above-quoted description, "Since the various forms are connected by intermediates, it is impossible to recognize infraspecific taxa." However, that's deeply-unsatisfying if cataloguing a collection that contains several now-synonymous specimens.

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  • $\begingroup$ Welcome to Biology Stack Exchange! I think this is a fine question, and I look forward to hearing (or rather seeing) the answers! $\endgroup$ – L.B. Oct 26 '15 at 22:47
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    $\begingroup$ Thank you! I appreciate the welcome, and hope this gets some answers myself. :-D $\endgroup$ – sehrgut Oct 26 '15 at 23:58
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    $\begingroup$ This seems like the type of thing that might vary from publication to publication. If you have access to the full book, maybe there's a key/glossary where you can find what the authors mean by these symbols $\endgroup$ – C_Z_ Oct 27 '15 at 14:22
  • $\begingroup$ I'd like to know the meaning of the triple bar myself. Incl. probably means "including." Your question may be largely answered by the Catalogue of Life, which cites Dorstenia crispa as a synonym for Dorstenia foetida ssp. lancifolia. $\endgroup$ – David Blomstrom Oct 27 '15 at 21:16
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According to the Taxon guidelines for authors (pdf, pg 205), a triple-bar (≡) indicates a homotypic synonym:

Homotypic names are cited in chronological order in a single paragraph with the identity sign (≡), followed by the type.

So, in your example, Dorstenia foetida was described on the basis of the same type specimen used by Forsskål in 1775 to describe Kosaria foetida -- or possibly a neotype was designated linking these two names, possibly by Schweinfurth in Bull. Herb. Boissier 4(App. 2): 120 in 1896. More information about the relevant type specimens would help sort this out.

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  • $\begingroup$ That makes sense. How does it play with "incl.", then? I see, then, that D. crispa var. lancifolia shares a type with the superceding name D. foetida ssp. lancifolia. What relationship does that type have to D. foetida, indicated by the incl.? Is it simply that the taxonomist preparing this monograph is indicating his belief that they all should share a type, even though currently they don't? $\endgroup$ – sehrgut Nov 4 '15 at 23:22
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    $\begingroup$ I'm afraid I have no idea! If I had to guess, I'd guess that "A: incl. B" means that all individuals associated with the name B are considered by the taxonomist to belong to their circumscription of name A, without the requirement that they share a homonym. In some cases, it looks like B is a subspecies or variety, suggesting that these should be subsumed into A and not considered a separate entity. I'd hoped someone more knowledgeable would chime in but since that hasn't happened yet, here's my somewhat-informed guess! $\endgroup$ – Gaurav Nov 20 '15 at 20:54

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