|Authors||M.D. Medel, P.J. López-González| |Title||Distribution
patterns in Atlantic hydroids| |Keywords||Hydrozoa;
zoogeography; faunal affinities; Atlantic Ocean.| |Abstract||The
present study is a first attempt to comparing the hydroid faunas
of the various Zoogeographie areas of the Atlantic Ocean. We
restricted ourselves to species of the orders Antho- and
Leptomedusae, of which 1050 species were taken into account. The
classification of zoogeographic areas used follows Ekman and
Briggs, with slight modifications; thus, the Strait of Gibraltar
is here considered as a separate zoogeographic area due to its
character of a transition zone between several areas in the
Northeastern Atlantic Region. Species were arranged into
Zoogeographic groups to compare the faunal composition of the
various Zoogeographic areas. The Dice similarity index was used
for each comparison.| The fauna of North-eastern Region can be
split into three groups of similarity: 1) that of the
Mediterranean and Lusitanian Provinces plus th