Electronic Supplement 3
|
Organisms
Diversity & Evolution 2 (2002) Electronic Supplement 3 |
|
Michael Schrödl:
Heavy infestation by endoparasitic copepod
crustaceans (Poecilostomatoida: Splanchnotrophidae) in Chilean opisthobranch
gastropods, with aspects of splanchnotrophid evolution.
print
version: Org. Divers. Evol. 2(1): 19-26. 2002 (full article)
electr. suppl.:
Part 1. Collecting sites and local prevalence of Ismaila spp.
pdf-format, 132 KB
Part 2. Parasitism of
opisthobranchs examined during this study. pdf-format, 108 KB
Abstract:
Copepods of
the family Splanchnotrophidae are very significant parasites of shell-less
opisthobranchs, but little information exists on their occurrence, infection
frequencies, and local or seasonal abundances. Using a quantitative faunistic
approach, 2257 potential hosts belonging to 47 opisthobranch species were
collected from 1991 to 1996 off the Chilean and Argentinian coasts, mainly by
SCUBA. Endoparasitic splanchnotrophids of the genus Ismaila were found
in 303 host specimens, corresponding to a 13% prevalence of infection. The
opisthobranch hosts were one sacoglossan, three doridoidean and four
aeolidoidean nudibranch species. In total, 12 Chilean opisthobranch species are
known to be infected with splanchnotrophids. This amounts to about 20% of all
shell-less opisthobranch species from Chile, and a remarkable 26% of all
splanchnotrophid hosts worldwide. Infection frequencies are low in most host
species, but reached 89-100% in certain populations of Thecacera
darwini, Okenia luna, Flabellina sp. 1 and Elysia
patagonica, representing the highest rates of infestation by
splanchnotrophids ever documented. In Thecacera darwini, the prevalence
was very low in northern Chile, consistently high in central Chile, and low in
the south. High infestation coupled with a high number of sympatric but
host-specific species indicate the coast of central Chile is a centre of
Ismaila evolution. The biogeography of splanchnotrophid genera is
discussed, and a hypothesis on their distributional history is
presented.
Key words: Chile, Opisthobranchia, parasite,
Splanchnotrophidae, Ismaila, biogeography, evolution
 |