Geophilomorph centipedes and the littoral habitat - Books and ...

A.D. Barber / Terrestrial Arthropod Reviews 4 (2011) 17–39 33
successfully and this explanation reasonably accounts for the presence in Africa and
South America of many, but of course not all, congeneric or conspecifi c centipedes”.
Th is hypothesis was supported by Pereira and Minelli ( 1993 ) and Pereira et al. ( 1997 ),
the latter writing “Th ere is a single specimen of Schendylops in the Natural History
Museum in London, too damaged for allow for confi dent specifi c identifi cation, but
good enough to allow a confi dent identifi cation as a member of a genus occurring,
with many species, on both sides of the Atlantic. Th is specimen was collected long ago
from Ascension Island, midway between Africa and South America, along the route
of the westbound South Equatorial Current”.
On both a local and a global scale, the varied nature of coasts will be likely to break
up species into a series of isolated populations which would favour genetic divergence.
Dispersal across oceans and to isolated islands would accentuate this eff ect. Th is may
be refl ected in variations in characters between populations at diff erent sites.
Geophilomorphs are convenient animals in which to study such diff erences by looking
at variation of numbers of leg-bearing segments at particular locations as described by
Lewis ( 1962 ) for Strigamia maritima and Shinohara ( 1961 ) for Tuoba littoralis . Arthur
and Kettle ( 2000 ) demonstrated a latitudinal cline in segment number in Strigamia
maritima in Britain, suggesting that climatic selection and local adaptation could be
responsible; Vedel et al. ( 2008 ) showed that, in laboratory experiments, temperature
regime infl uences the number of leg-bearing segments that develop in this species and
which could provide an explanation for this phenomenon.
Conclusions
It can be seen that there is a wide diversity of species of littoral centipedes around the
world but with obvious and sometimes surprising gaps in our knowledge including the
shortage of records from the coasts of eastern North America, most of Africa including
South Africa and large parts of Asia. Th ere are also littoral centipedes, presumably
geophilomorphs, reported in the literature from a variety of locations when, apparently,
no identifi cation was made or specimens kept e.g. Cape Verde Islands, Galapagos
(Crossland, 1929 ), Colombia, Panama, Costa Rica (Polhemus and Evans, 1969 ),
North America (Hoff man and Carlton, 2007 ). Th ere may also be described species
that have been missed in this survey.
On northwestern European coasts alone there are at least eight or so genuini or indifferenti
species described (depending on taxonomic issues, etc.) and the number from
Japanese shores is comparable. It would be surprising if such relative species richness
was not replicated in at least some other regions and that areas from which only one or
two or no species have been described are probably in many cases much under recorded.
It seems highly likely, therefore, that there are further, as yet undescribed, littoral
geophilomorphs and/or a wider distribution of known species than has already been
recorded.
What we have is a somewhat incomplete picture but one that suggests that, wherever
conditions are favourable (outside the polar regions), seashore geophilomorphs are