Peter Koller

Peter Koller

Tel: (+49) 0941 / 943 2152

Welcome to the world of Sulawesian freshwater crabs.

bild1 Thanks to Christoph Schubart I had the opportunity to conduct my Diploma thesis on freshwater crabs of the Indonesian island Sulawesi during 2003/ 2004. The topic of the thesis was "Rekonstruktion der Besiedlung der Malili-Seen (Sulawesi, Indonesien) durch Süßwasserkrabben (Crustacea: Decapoda: Brachyura: Parathelphusidae)" and therefore my main interest was - and still is - to reveal the phylogenetic relationships within the endemic freshwater crab species of the Malili lake system and between these and the species in the surrounding rivers with the goal to get an idea how the colonization of the lakes and speciation took place.

The reason for studying Sulawesi and the Malili lake system is for one the special role of Sulawesi for the understanding of the biogeography in this part of the world due to its situation between the tectonic plates of Asia and Australasia and for the other the high degree of endemism - not only of crab species, but also other taxa like fishes, molluscs or shrimps - within the ancient lakes of the Malili region, L. Matano, L. Mahalona and L. Towuti. As it is for the crabs, there are right now five species (Parathelphusinae) known belonging to three different ecotypes, e. g. generalists, detritivores and molluscivores.


The methods I use to study these subjects are genetic sequence analyses of mitochondrial (16S rDNA, Cytochrome oxidase I) and nuclear (ITS 1, 5.8S rDNA, ITS 2) markers and morphometric and morphological comparisons between species and populations. Concerning the morphology, I am placing current emphasis on the first gonopod G1, as it is considered a good character for inferring phylogentic relationships.

Right now it looks like there are at least two independent colonization events of the Malili lakes with the molluscivore genus Syntripsa establishing in the lakes independently from the unspecialized Parathelphusa species and the detritivore Nautilothelphusa zimmeri. A peculiar result of my work is the special relationship between N. zimmeri and P. ferruginea. In this case, contradictionary results for the mitochondrial data on the one side and nuclear and morphological data on the other side are at hand and probably a case of mitochondrial introgression.

For the future, I want to extend my work on the river forms of the whole island, to investigate further the phylogeny of the crab fauna of the Malili and Poso regions and also different adaptions of the ecotypes concerning feeding morphology.