Beschreibung:
<jats:p><jats:bold>Abstract. </jats:bold> On the central coast of Victoria, Australia, the ascidian <jats:italic>Pyura stolonifera</jats:italic> (H<jats:sc>eller</jats:sc>. 1878) assumes 2 morphs. a yellow form living exclusively on inner shores, and a brown morph mainly on outer coasts. Distributional surveys, morphological analyses and field transplant experiments were conducted as part of a multidisciplinary investigation designed to elucidate the environmental and genetic components of dimorphism in this species. Distributional surveys revealed that the 2 morphs have a parapatric distribution. Morphological analyses showed striking differences between morphs in colours of tissue types, external anatomy, morphometry and gravimetry. Possible ecological significances of this morphological differentiation are discussed. Transplant experiments, in which morphs were moved within and between habitats, yielded no evidence for morphological plasticity in adults of this species for the great majority of characters examined.</jats:p>