Toward a revision of the genus Synura, section Petersenianae (Synurophyceae, Heterokontophyta): morphological characterization of six pseudo-cryptic species
Abstract
Morphological data, based on transmission and scanning electron microscopy of silica scales, are provided for six genetic lineages of the Synura petersenii species complex as revealed by multiple genetic markers (internal transcribed spacer rDNA, psaA, rbcL and cox1). The morphology allows clear distinction of all six lineages, as well as their separation from all other taxa in section Petersenianae.
The lineages are redefined or described as new species in accordance with previously published molecular and morphometric evidence as S. petersenii, S. glabra, S. truttae comb. et stat. nov., S. americana sp. nov., S. macropora sp. nov. and S. conopea sp. nov. The section Petersenianae further includes nine taxa with well-known ultrastructural characteristics.
Four have status of species (S. australiensis, S. longisquama, S. macracantha and S. obesa), and five have been described as different formae of S. petersenii sensu law (S. petersenii f. asmundiae, S. petersenii f. bjoerkii, S. petersenii f. columnata, S. petersenii f. praefracta and S. petersenii f. taymyrensis). All 15 taxa can be distinguished by the shape of the body scales, scale dimensions, keel shape, number of and distance between struts, degree of interconnections between struts, and the size of base plate pores, keel pores, and base plate hole.
A key to species is provided. The biogeography of newly defined taxa is discussed based on the morphological data obtained from previously published reports.