Loading ...
Sorry, an error occurred while loading the content.

Re: FW: [beemonitoring] in search of Bombus cockerelli [1 Attachment]

Expand Messages
  • John S. Ascher
    plot malar length against breadth of the mandible at its base for all of the specimens labelled cockerelli, together with samples of vagans, sandersoni,
    Message 1 of 7 , Jul 21, 2011
    • 0 Attachment
      "plot malar length against breadth of the mandible at its base for all of
      the specimens labelled cockerelli, together with samples of vagans,
      sandersoni, mixtus, bolsteri, vagans s. str., and balteatus."

      The AMNH cockerelli have long malar spaces as in vagans and unlike mixtus
      (and because of this had been misdet. as flavifrons), but not very long as
      in balteatus. As mentioned before, the problem is that these are small
      workers, and judging malar space of these is more difficult than for
      queens.

      As far as I know B. vagans occurs in Washington and Idaho (see Stephen
      revision) and Montana but is not well known from further south in the
      Rocky Mountains. I would like to see more details of reports from Wyoming,
      Utah, and Colorado. It would certainly be useful to better document the
      southern distribution of vagans in the west. As far as I know, there is a
      big gap between the southernmost sites where vagans is well known and the
      NM localities for cockerelli, so if cockerelli is a form of vagans it is a
      remarkable disjunction.

      John


      >
      >
      > Subject: RE: [beemonitoring] in search of Bombus cockerelli
      > Date: Thu, 21 Jul 2011 10:42:47 +0100
      > From: P.Williams@...
      > To: sheila_123@...
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      > Hi Sheila
      >
      >
      >
      > Please would you be kind enough to post
      > this for me to the beemonitoring discussion group:
      >
      >
      >
      > A few thoughts on the cockerelli issue:
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      > JA: After further study inspired by Doug's
      > comments I find that the malar
      >
      > space of our "cockerelli" is indeed longer than in mixtus.
      > Furthermore, T2
      >
      > is entirely yellow, whereas mixtus should have at least some black hairs
      >
      > on the apicoposterior margin.
      >
      > In the
      > absence of COI barcode data, the best way forward right now might be to
      > plot
      > malar length against breadth of the mandible at its base for all of the
      > specimens
      > labelled cockerelli, together with samples of vagans, sandersoni, mixtus,
      > bolsteri,
      > vagans s. str., and balteatus. This needs to be done preferably by one
      > person, because there can be substantial differences among observers in
      > the
      > selection of measuring points.
      >
      > Further
      > to the earlier comments on identification of B. sandersoni, I think it
      > must be
      > diagnosed with reference to malar length, or to DNA data such as COI
      > barcodes.
      >
      > DY: I'm now very puzzled at the
      > nature of the AMNH specimens; the USNM
      >
      > and UCR specimens have fairly long malar spaces, indistinguishable
      >
      > from vagans or flavifrons (note that of the five diagnostic features
      >
      > I gave for flavifrons vs. cockerelli, malar space was not one of
      >
      > them), and much longer than New Mexico specimens of mixtus. I put up
      >
      > two photos of the head of the UCR specimen on our project's Facebook
      >
      > page at http://www.facebook.com/pages/DBCNet/108649695863427
      >
      > Many
      > thanks for this - I had not seen it until this morning. Unfortunately the
      > picture is insufficiently clear that I can take measurements with
      > confidence.
      >
      > Attached
      > is an image of the B. sandersoni specimen from Tennessee that I mentioned
      > in an
      > earlier message.
      >
      > DY: I'm beginning to have suspicions
      > that malar space is a phenotypically-plastic trait,
      >
      > and that by building our keys around that one character, we may be
      >
      > obscuring actual species limits. Didn't Jim Thomson (and maybe a few
      >
      > others, like Claire Kremen) do some work suggesting competitive
      >
      > displacement in tongue length?
      >
      > I know
      > of some evidence for weak allometric variation within some bumblebee
      > species in
      > tongue length, which is likely to covary with malar length, but a
      > suggestion
      > that malar length is strongly plastic within bumblebee species and shows
      > competitive displacement seems unlikely from my experience. It needs
      > evidence and it would be interesting to see the references. What is much
      > more evident is that specimens are often misidentified so that there are
      > mixed
      > series associated with a particular name. We have to be careful that all
      > of the “cockerelli” are in fact of the same taxon, whatever that
      > taxon may prove to be.
      >
      > Paul Williams
      >
      > NHM, London,
      > UK
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >
      >


      --
      John S. Ascher, Ph.D.
      Bee Database Project Manager
      Division of Invertebrate Zoology
      American Museum of Natural History
      Central Park West @ 79th St.
      New York, NY 10024-5192
      work phone: 212-496-3447
      mobile phone: 917-407-0378
    Your message has been successfully submitted and would be delivered to recipients shortly.