engleski

Diatom genus Poulinea as epibiont on Adriatic loggerhead sea turtles

Poulinea Majewska et al. is a marine diatom genus originally described from carapaces of olive ridley sea turtles (Lepidochelys olivacea) but has since been reported on other sea turtle species as well. Although phylogenetically distant from freshwater genus Gomphonema, Poulinea and genera such as Tripterion Holmes et al., Chelonicola Majewska et al., and Medlinella Frankovich et al. are often referred to as marine epizoic “gomphonemoids” due to the transapical heteropolarity of their valves. It has recently been noticed, that members of the above-mentioned taxa are characterized by remarkable morphological plasticity, which seems to be particularly high in Poulinea. The aim of the current study is to characterize the Adriatic Poulinea populations associated with local loggerhead sea turtles (Caretta caretta) using both morphological and molecular analyses. Diatom samples for morphological observations were obtained from the skin of several frozen loggerhead carcasses collected between 1995 and 2002. Abundant Poulinea populations were found on seven (out of 14) animals, each time showing a pronounced morphological variability. Moreover, several monocultures of Poulinea spp. were obtained from living sea turtles. Samples were analysed under light and scanning electron microscopy. In addition, three molecular markers (rbcL, psbC, and SSU) were sequenced from our cultures. This research offers new insights into the phylogeny and ecology of Poulinea and related taxa and sheds more light on the crypto and pseudo-crypto diversity in these small and poorly-known epibionts.

diatoms, epizoic ; marine “gomphonemoids” ; morphology ; phylogeny

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