World Congress of Malacology Antwerp ... - Unitas Malacologica

Malacological studies in a mega-diverse and poor country as Brazil
Simone, Luiz Ricardo L.
Museu de Zoologia da Universidade de São Paulo, Cx. Postal 42494, 04299-970 São Paulo, SP
Brazil,
Email: lrsimone@usp.br
The Malacofauna from Brazil, both marine and continental, are the best studied from South America.
However, informal estimative is that it is no more than a third known. The problems are still more
urgent because of quick environmental degradation and the weak resources for zoological studies in a
country that more than 20% are deprived people. Certainly several species have been lost before they
at least have been known.
Two examples of research in Brazilian territory are shown. One of them is dredges provided by shell
dealers in Canopus Bank, NE Brazilian coast, relatively close and shallow, in which several new
species were obtained. The other is an analysis based on a catalogue recently published, that
inventoried the entire known malacofauna of the Brazilian ecosystems. This is an important source of
data, showing the main known groups and the bio-communities weaker studied.
Species diversification in ancient lakes: patterns of morphological and ecological differentiation
in Tylomelania (Cerithioidea: Pachychilidae) from Lake Poso, Sulawesi, Indonesia
Simonis, Jutta 1 ; von Rintelen, Kristina 1 ; Marwoto, Ristiyanti 2 ; von Rintelen, Thomas 1 ;
Glaubrecht, Matthias
1. Museum of Natural History, Humboldt University Berlin, Invalidenstrasse 43, 10115 Berlin,
Germany,
Email: jutta.simonis@museum.hu-berlin.de
2. Museum Zoologicum Bogoriense, Research Center for Biology, LIPI, Cibinong 16911, Indonesia
Ancient lakes and their endemic faunas are model systems for the study of evolutionary patterns and
add to our understanding of speciation processes. Species level taxonomy often remains poorly
studied in ancient lake radiations, though, presenting a major obstacle for evolutionary hypothesis
testing. We here present for the first time morphological and ecological data for a species flock of the
viviparous freshwater gastropod Tylomelania (Cerithioidea, Pachychilidae) in Lake Poso, Sulawesi,
Indonesia.
Only four species of Tylomelania have been described from Lake Poso so far, plus three species from
the outflowing river that show lacustrine features as well. Recent sampling campaigns in the lake
have revealed a high diversity of hitherto undescribed forms, however. At least 24 morphospecies can
currently be distinguished based on their characteristic shell and radula morphology. A unique feature
of Lake Poso Tylomelania is the conspicuous body colouration in some species. Many species show
clear substrate preferences, with several taxa occurring on just one substrate such as e.g. rocks, wood
or mud. In addition, some taxa were found to exhibit a marked depth preference as well.
The diversity of radula forms in Lake Poso Tylomelania is striking and even exceeds that found in the
other ancient lake system on Sulawesi, the Malili lakes. Common to both lake systems, however, is
the correlation between radula morphs and substrates documented here for the first time for Lake
Poso. Some radula types are species specific and several similar radula forms are characteristic for
certain substrates such as e.g. very short and dense radulae for soft substrates and enlarged pointed
radulae on rocks. Some highly derived radula forms seem to have evolved in parallel in both ancient
lake systems on Sulawesi.
207