cryptic and sibling species

Detlev Cordes dcordes at BIOLOGIE.UNI-ERLANGEN.DE
Mon Oct 18 10:21:08 CDT 1999

At 15:17 Uhr -0700 17.10.1999, Ken Kinman wrote:
>     Please correct me if I am wrong, but are sibling species pretty much
>equivalent to "cryptic species" (closely related, but separate species which
>are morphologically almost identical, but distinguishable by molecular and
>other means---such as differences in bird songs, which I believe led to the
>discovery of some avian sibling species).

In my opinion the two terms are not equivalent - At the department here we
think that "sibling species" in almost all cases are also "cryptic", but
"cryptic species" not necessarily are "siblings"! In wolf spiders (the
group of my research) the term "cryptic species" has been used often for a
larger group of species (sometimes 4 or 8 taxa) that are difficult to
separate by means of their morphology - then the behaviour turned out to be
a powerful tool to separate them (as in the above mentioned example for
        "Cryptic species" does not say anything about their phylogenetic
relationships - they are difficult to recognize, and need to be
investigated with more complicated methods - behavioural comparison,
molecular approach -  so this is our problem, that we first use our eyes to
separate species. Instead "sibling species" are defined by means of their
phylogenetic "sister relationships" (in german: "sibling species" =
"Zwillingsarten") and in my opinion they are TWO taxa only.

Two examples - 1. A taxon of European wolf spiders (Alopecosa accentuata)
turned out to comprise two very similar (genitalia, outer appearance)
biospecies - "sibling species", obviously sharing a high degree of
phylogenetic relationship. This came out after sorting individuals from
different populations after their behaviour and ecology. 2. In an other
European group 6 taxa (Pardosa lugubris group) are extremely difficult to
recognize (morphology) but comparatively easy to separate after their
behaviour -- these are 6 "cryptic species". A closer analysis of
behavioural and molecular similarities may lead to a reasonable definition
of TWO "sibling species" inside this group - the two that share ONE

Kipling Will wrote:
>Jim Liebherr and I used "cryptic sibling" in our discussion of  a beetle
>species that we described.
Your example is wonderful for the term "cryptic" - the wings/remains of
wings, hidden under elytra. For me your usage of "cryptic siblings" is
somehow "double said".


Dr. Detlev Cordes
Institut fuer Zoologie II, Universitaet Erlangen-Nuernberg
Staudtstrasse 5, D - 91058 Erlangen, Germany
  Fax: ++49-9131-858060
  email: dcordes at

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