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

32 A.D. Barber / Terrestrial Arthropod Reviews 4 (2011) 17–39
1954 ) and the myriapods of St.Helena (Matic and Darabantu, 1977 ) all of which
include European species. Crabill ( 1964 ) thought that Maoriella edentatus (Attems,
1947) described from Tahiti (no locality details) might possibly be an aberrant
Maoriella macrostigma Attems 1903 transported from New Zealand by early Polynesian
voyagers; Maoriella is a genus known otherwise only from New Zealand with one species
from Australia. “Terrestrial” (especially soil) animals, especially those associated
with agriculture or similar practices, would seem to be likely to be spread this way
rather than sea shore organisms although the possibility of the latter being carried in
ship’s ballast should not be forgotten.
Accidental dispersal by rafting of animals e.g. on plant debris (hydrochory) is certainly
seen as a likely dispersal mechanism, for animals and littoral species are in an
optimum situation for this, both in terms of being accidentally carried away and of
establishing themselves when they arrive at a suitable destination. Suomalainen ( 1939 )
had reported on Pachymerium ferrugineum fl oating on sea water for as long as 31 days
before sinking and long survival when submerged in such water. Anecdotally, Nesrine
Akkari ( pers. comm .) described how a live Pachymerium ferrugineum was taken directly
in a landing net from the water in a shallow lagoon in Tunisia by a colleague who was
collecting mosquito larvae. Interestingly, this species is probably tone of the most widespread
centipedes in the world. Fossil evidence suggests that rafting occurred in palaeooceans
and during recent centuries the composition and abundance of fl oating items
has been strongly aff ected by human activities; it is suggested that rafting continues to
be an important dispersal in present-day oceans (Th iel and Gutow, 2004 ).
Th ere is, in fact, very limited quantitative data on the extent to which even insects
actually survive as drifters and most studies on animals spreading by rafting concentrate
on marine species (e.g. Th iel and Gutow, 2005 ). Drifting vegetation has been
found up to 16km off shore which supported many insects although only 25% of it had
living terrestrial animals and no living insects were found in vegetation collected 160km
off shore (although colonies of ants have been reported in drifting wood) (Bowden and
Johnson, 1976 ). Even if the chances of survival are small, the possibility remains for
transport in this way. Th e pseudoscorpion Apocheiridium pelagicum Redikorzev, 1938
was fi rst collected 200 miles (320km) at sea in plankton nets; its habitat is in reefs
constantly submerged by the sea (Roth and Brown, 1976 ). Th e fact that heteropterous
bugs ( Halobates spp.) can live on the surface of the open ocean suggests also that there
is no fundamental reason why arthropods of terrestrial origin should not be able to
survive in this environment for a period of time and be dispersed over wide distances.
Crabill ( 1960 ) discussed the issue of rafting as a means of distribution of centipedes
referring to Caritohallex minirrhopus , Balophilus riveroi and Schendylus virgingordae collected
in West Indian beach drift and to specimens of Pectiniunguis from seaweed on a
beach in Florida Key. He thought that animals might not be “discomfi ted much or at
all perhaps” in the wood or under the bark of fl oating trees or bushes and suggesting
that, although many, perhaps the majority, would perish, over the immense length of
time and the millions of such voyages that were begun, many must have reached land
and survived. He went on to comment that “during the immense stretches of time of
the past some centipedes – they may well have been Schendylidae – made the journey