[Taxacom] "Masteria mystery" solved?

[Kenneth Kinman]

Hi Michael,  
      Well, I suggested that the center of origin of
Masteria was in the Antarctica area.  Antarctica itself was relatively
warm in the Mesozoic, but might have not been warm enough for Masteria,
unless they retreated into caves during the winter months (which is
possible, since many Masteria seem to like caves).    
   
      However, I would lean more toward an origin a bit further north
(perhaps Argentina).  Argentina is likely where the entire Subfamily
Masteriinae would have originated.                    
                        --------Ken
                   
P.S. I wonder if anyone has explored any caves in Borneo looking for
Masteria.   
---------------------------------------------- 
Michael Heads wrote: 
Hi Ken, 
  I'm not quite sure that I follow your line of reasoning. Are you
suggesting a center of origin for Masteria in Antarctica? Platnick (AMNH

spider website) does not accept that the Indian species of Ischnothele

belongs in the genus (America/India would be a very unusual
distribution). He lists Euagrus from Taiwan, Guatemala to USA (standard
trans-tropical Pacific) and South Africa (standard
trans-Atlantic). The Atlantic opened about the same time that the
central Pacific plateaus formed (mid-Cretaceous), which suggests a
simple global process for Euagrus.    
I don't think Masteria is (currently) an island-hopper - all the

species in the Caribbean and all but one in the Pacific are endemic to
single archipelagos, compatible with allopatric differentiation in a
phase of immobilism. On the other hand, its Cretaceous ancestors may
well have been actively dispersing when they colonized the new areas

of land provided by the plateaus (possibly from prior islands in the
region).   You suggest Mesozoic vicariance for Masteria and I
agree. The large igneous plateaus in the central Pacific have
drifted long distances westward (Ontong Java plateau etc.) and eastward
(Inca plateau etc.). They included forest (or at least trees) and
presumably there were also animals there, so... what happened to
them? Could they have been incorporated into America along with the
plateaus? This might explain the distinctive distribution of
Masteria in America (only in the Caribbean), and in the west Pacific
(west only to New Guinea - Philippines).   Michael 
Wellington, New Zealand. 
My papers on biogeography: http://tiny.cc/HeadsPubs My new book
'Molecular Panbiogeography of the Tropics': http://tiny.cc/MolPanbio 
________________________________  
 From: Kenneth Kinman <kennethkinman at webtv.net> 
To: taxacom at mailman.nhm.ku.edu 
Sent: Tuesday, 10 January 2012 3:53 AM 
Subject: [Taxacom] "Masteria mystery" solved? 
  
Hi Michael,            
    I think I've solved a lot of the mystery surrounding the
Masteria disjunction.  And thankfully, I didn't need either
panbiogeography or terranes floating long distances east and west across

the Pacific.  
      I looked beyond subfamily Masteriinae to other subfamilies
of Dipluridae, and the distribution of Ischnothele jumped out at me
(neotropics plus one species in India).  Euagrus is somewhat similar,
but involved South Africa instead of India.        This pretty
clearly points to vicariance (during the Mesozoic) centered far to the
south (in the area of Antarctica), and of course any intermediate
species still in the southern polar region would have eventually gone
extinct (from the cold in particular).        So subsequent
dispersal of Masteria (by rafting, ballooning, or whatever) would have
been over shorter distances, perhaps the longest being east to Fiji. 
This genus is clearly a fairly good island-hopper (in both the Pacific
and Caribbean).  On the other hand, genus Ischnothele didn't need to
island-hop, but simply rode on India as it travelled north to Asia.  
    Therefore, I predict that Masteria will be found on other
islands in the Pacific, perhaps even Borneo.  However, diplurid
spiders seem to have had little luck invading very much of Eurasia
beyond the area around India, so competitive exclusion by other
mygalomorphs could be a factor (perhaps even in Borneo).        

    --------Ken Kinman  
______________________________________