EASIN - European Alien Species Information Network

Kostas Tsiamis
8/6/2018 - 1:57 PM

Thread Opening Text:
Need to clarify if Eudendrium merulum is alien in the Mediterranean Sea; alien, native or cryptogenic (alien status not sure)?

Stefano PIRAINO
8/6/2018 - 2:56 PM

The species has been described from Australia (Watson, 1985). Type locality: Bass Strait, Victoria, Australia. It was reported for the first time in the Mediterranean Sea a few years later by Bavestrello and Piraino (1991) who found several fertile colonies (in Ligurian Sea and in Southern Thyrrenian Sea) that matched the diagnosis of E. merulum. The identification of E. merulum is facilitated by a distinctive cnidocyte type, i.e. large microbasic euryteles around the glandular ring, the hypostome and on the gonophores, characterized by three large spines composed by revolving lamellae. Taking in consideration that in the Fifties and Sixties a considerable amount of work was made on the hydroid fauna of the Mediterranean (including that made by J Picard on the Eudendriidae, probably one of the best studied and conspicuous hydroid family), it seems more realistic to consider the appearance of E. merulum in the Mediterranean Sea as new introduction rather than the new recognition of a native species (with bipolar distribution) previously confused with different sister species (e.g. E. ramosum). 

Watson J.E., 1985. The genus Eudendrium (Hydrozoa: Hydroida) from Australia. Proceedings
of the Royal Society of Victoria 97(4): 179-221.
Bavestrello G., Piraino S., 1991. On two Eudendrium (Cnidaria, Hydrozoa) species from the
Mediterranean Sea. Oebalia, n.ser., 17: 197-207.

Kostas Tsiamis
8/7/2018 - 7:13 AM

Thread Closing Text:
Status in the Mediterranean Sea: alien

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