Diaz-Tapia P., Barbara I., Cremades J., Verbruggen H. & Maggs C.A. (2017)
Three new cryptogenic species in the tribe Polysiphonieae (Rhodomelaceae, Rhodophyta)
Phycologia 56: 605-623


During our sampling surveys of the tribe Polysiphonieae in Spain and Australia, three previously unrecorded species were collected. Based on molecular and morphological evidence they are proposed as new species. Polysiphonia delicata sp. nov. and P. radiata sp. nov. belong to Polysiphonia sensu stricto and have the characters that define this group (rhizoids in open connection to pericentral cells, branches independent of trichoblasts, 4-celled carpogonial branch and spermatangial branches replacing trichobasts). They differ from members of this group either by rbcL sequence divergences greater than 4.5% and/or by morphological characters. The third species is placed in Melanothamnus, as M. pseudoforcipatus sp. nov. In agreement with the morphological delineation of the genus, it has plastids lying only on the radial walls of pericentral cells. It can be separated from most other members of the genus by having naked segments between trichoblasts or branches and/or rbcL sequence divergences higher than 4%. In Galicia, Spain, both Polysiphonia species were mainly collected in marinas and on piers, while M. pseudoforcipatus was found at a site close to oyster aquaculture facilities. P. delicata was also found in Victoria, Australia, and the potentially non-native status of these three species in relation to their known distribution is discussed.

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