The genus Myriapora. Pathways of evolution.
Schäfer, P., Bader, B., Nikulina, E.
Myriapora is an evolutionary young cheilostome bryozoan genus
restricted to the Northern hemisphere. It is known with at least six
species from mid Tertiary to recent times. Earliest, unproved reports
of the type species M. truncata are from the eocene of Rumania,
followed by the Oligocene of Germany, the Miocene (Tortonian) of the
Paratethys (Vienna basin) and the Guadalquivir basin (SW Spain) and NW
Marocco, and from the lower Pliocene of Netherlands. Today,
M. truncata is an exclusively Mediterranean species. It is
distinguished from the fossil populations by its distinctly ssed and
M. fungiformis was found in Oligocene (Rupelian), near-coast sediments
of epicontinetal Europe, M. bugei has its distribution around the
oceanic islands of the Central Atlantic (Azores, Great Meteor
Bank). Fossil occurrences are restricted to the Miocene (Upper
Tortonian, Messinian) of NW Marocco).
In contrast to the former species, M. coaractata, M. orientalis,
M. subgracilis and M. subgracilis variabilis are restricted to
cold-temperate to polar shelves of the N Atlantic, Siberian Sea and N
Based on their different wall ultrastructures (apomorphies), two
phylogenetic lineages are considered as sister groups. According to
this hypothesis, the taxon Myriapora Blainville is based on the types
species Millepora truncata Pallas; adelphotaxon is Leieschara M. Sars
based on the types species L. coarctata Sars. Thus, the formerly
revised taxon Leieschara M. Sars should be re-established.
The hypothetical phylogeneic tree is confirmed by the biogeographic
distribution of the two clades. Myriapora is a mediterranean(Central
Atlantic, warm-temperate taxon, while Leieschara is restricted to
This hypothetical phylogenetic tree is based exclusively on
morphologic characters. As a next step, the attempt is undertaken to
test the tree by molecular genetics.