Diversity and distribution of shallow water marine molluscs of Sabah, with a focus on morphological and ecological differentiation of turbinidae/genus turbo/lunella

This study examined the biodiversity and distribution of shallow water marine molluscs in the near shore and shallow waters of Sabah, Malaysian Borneo and surrounding areas. The main focus of this study is on Gastropoda and to a lesser degree also on Bivalvia. Although other classes (Cephalopoda, A...

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Bibliographic Details
Main Author: Markus Ruf
Format: Thesis
Language:English
Published: 2010
Subjects:
Online Access:https://eprints.ums.edu.my/id/eprint/10105/1/mt0000000503.pdf
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Summary:This study examined the biodiversity and distribution of shallow water marine molluscs in the near shore and shallow waters of Sabah, Malaysian Borneo and surrounding areas. The main focus of this study is on Gastropoda and to a lesser degree also on Bivalvia. Although other classes (Cephalopoda, Aplacophora, Opisthobranchia, Scaphopoda, Polyplacophora and Monoplacophora) were occasionally collected, they are excluded from this thesis based solely on time and logistical constrains. One of the main goals of this research is not only to determine the distribution and diversity of mollusks, but also to establish the first reference-collection for molluscs in the State of Sabah to be located at UMS in the "BORNEENSIS" Biodiversity collection. Sampling of specimens was conducted at various points along the Sabah coastline, using various collecting methods. At 174 locations, a total of 2,772 sample transects, 45 market investigations, 32 sand samples and 54 hours of trawling produced 890 species out of 284 genera and 75 families of gastropods along with 261 species out of 131 genera and 42 families of bivalves. Altogether 10,345 specimens and shell fragments were collected and where possible identified. The gastropod families with more than ten species per family comprised the Buccinidae, Bursidae, Cassidae, Cerithiidae, Columbellidae, Conidae, Cypraeidae, Ellobiidae, Fasciolariidae, Hipponicidae, Mitridae and Costellariidae, Muricidae, Nassariidae, Naticidae, Neritidae, Olividae, Ovulidae, Ranellidae, Strombidae, Terebridae, Trochidae, Turbinidae and the Turridae. The bivalve families with more than ten species per family comprised the Arcidae, Cardiidae, Mytilidae, Ostreidae, Pectinidae, Spondylidae, Tellinidae and the Veneridae. Several rare and one "lost" species (Cyclina orientalis, Sowerby, 1852) were discovered but no endemic molluscs were found. Each of the habitats examined had a unique mollusc fauna compared with other habitats. As an example of further, more detailed analysis of the local mollusc fauna and as a benchmark for future studies, one mollusc family (the Turbinidae, Vetigastropoda) was selected for more detailed morpho-spatial examination. The analysis of morphological differences was performed for six preselected species to show their morphological and ecological differentiation such as the variation in biometrics, habitat ranges and preference, as well as the analysis of the radulae, micro habitats and observed behaviors. Results from this study indicate that Sabah has an extremely diverse marine mollusc fauna, several orders of magnitude greater than previous published accounts, and it is suggested measures should be taken to protect this valuable natural resource. The results from the Turbinidae study revealed that the six species show substantial biometric and morphological differentiation. No previously unrecognized cryptic species were found, but strong ecological differentiation could not be detected. This thesis should inspire students and malacologists alike to further expand on this list of local mollusc fauna, with a view to developing a comprehensive, family-wide coverage of the Gastropoda of Sabah; and to easily identify molluscs in combination with the above mentioned reference collection.