[Taxacom] North America, Central America + S.E. Asia sister taxa

Kenneth Kinman kennethkinman at webtv.net
Thu Dec 29 21:05:30 CST 2011


Hi John and Don,
      It is not surprising that there are so many such Pacific patterns,
since there are a number of different ways by which they could have
arisen, including northern Beringian dispersal, southern Antarctic
dispersal, or even direct dispersal across the Pacific (as well as even
broader original distributions undergoing severe geographic extinction
of intermediate taxa).      

       Interestingly, any of the three mentioned below (Enicoscolus,
Pitnus, and Batis) seem to me to be good candidates for direct dispersal
across the Pacific via rafting.  Pitnus are leaf-miners which could feed
on the leaves of rafting trees, Batis plants are a good candidate to
survive on rafts since they are extremely salt-tolerant, and even
Enicoscolus larvae could easily feed on the dying matter in such rafts.
Not at all surprising that Pitnus is even found in the Galapagos.    
               --------Ken
----------------------------------------------------------

John Grehan wrote:   
     This observation points out the reality of Pacific patterns. The
NG/Aust-C America distribution is relatively unambiguous with respect to
the main massings being immediately adjacent to the Pacific basin. In my
Galapagos study I found the saltwort genus Batis to also be in north
Queensland/Papua NG as well as Central America/Baja
California/Galapagos/Caribbean/Atlantic Brazil. 
The central USA-SW Australia pattern is less unambiguous as it is not
obvious which ocean basin is involved. Further outgroup comparisons
might help. Also in my Galapagos study I found the genus Pitnus recorded
from the Caribbean/Central America/W Mexico/SW USA/Galapagos and
southern/SW Australia. 
Trans Pacific patterns are almost beyond counting, being so frequent and
taxonomically broad. 
John Grehan 
-----Original Message----- 
From: Don.Colless at csiro.au [mailto:Don.Colless at csiro.au] 
Sent: Friday, December 23, 2011 11:28 PM 
To: John Grehan 
Subject: RE: [Taxacom] North America, Central America + S.E. Asia sister
taxa 
As a minor contribution to this thread, may I record the genus
Enicoscolus, with a species in Papua-New Guinea and North Queensland and
the rest in central America. I cannot conceive this as due to
convergence. There is another genus, name forgotten for the moment, with
a species in central USA and one in SW Australia. The identity was
confirmed  by a very surprised - and eminent - North American Dipterist. 
Donald H. Colless 






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