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Hannover, Germany

Sterrenburg F.A.S.,Stationsweg 158 | Tiffany M.A.,San Diego State University | Hinz F.,Alfred Wegener Institute for Polar and Marine Research | Herwig W.E.,Freidingstrasse 11 | Hargraves P.E.,Florida Atlantic University
Phytotaxa | Year: 2015

Seven new Haslea species demonstrate that the genus has evolved a richer morphological repertoire than so far reported. H. feriarum sp. nov. has a valve contour suggesting an Amphora; H. staurosigmoidea sp. nov. has a sigmoid valve with a pseudostauros; H. tsukamotoi sp. nov. and the closely similar H. meteorou sp. nov. possess uniquely shaped external central raphe endings and a fully sideways-tilted internal raphe system; H. clevei sp. nov. and H. avium sp. nov. also have central raphe ending shapes not yet described in the genus; H. amicorum shows interrupted longitudinal fissures besides the continuous fissures characteristic of Haslea. A survey of the Haslea species described, for differentiation of our taxa, led to two conclusions: 1) the data in the protologue of H. indica Desikachary & Prema are spurious and 2) “Navicula” duerrenbergiana Hustedt is here transferred to the genus Haslea. The basic Haslea morphology is a sandwich-type valve, with a grate-like inner layer (here called basal layer) and an outer layer (here called tegumental layer) perforated by continuous longitudinal fissures. These two layers are shored by upright longitudinal “bulkheads”, here called saepes, seen to be perforated in the valves that permitted their observation. This morphology is closely similar to that of Gyrosigma (and Pleurosigma). The great variety of central external raphe ending patterns in Haslea, Gyrosigma and Pleurosigma is shown and discussed. © 2015, Magnolia Press. Source

Gyrosigma tenuissimum (W.Sm.) J.W.Griffith & Henfr. was examined in the original material and an emended description is presented. Its protologue contains an error of taxonomic significance: in the type material, the valve and raphe sternum do not show the considerable flexure described and illustrated in Smith (1853). A comparison with Gyrosigma coelophilum N. Okamoto & Nagumo revealed that the latter, although similar in several characters, differs sufficiently in others to warrant separate specific status. Descriptions of two new taxa are given: Gyrosigma tenuissimum var. gundulae var. nov. and Gyrosigma baculum sp. nov. Both show very fine longitudinal striae at or beyond the limit of ordinary light microscopy and are practically non-sigmoid. © 2014 Magnolia Press. Source

Lobban C.S.,University of Guam | Ashworth M.P.,University of Texas at Austin | Car A.,University of Dubrovnik | Herwig W.,Freidingstrasse 11 | Ulanova A.,Uppsala University
Diatom Research | Year: 2015

Licmosphenia Mereschkowsky (Licmophorales: Licmophoraceae) is distinguished from Licmophora C. Agardh almost entirely by the presence of an apical window in the septum of the valvocopula. Recently, SEM images of three new species, all with coarse striae, showed that the valve morphology was indistinguishable from a group of Licmophora species including L. ehrenbergii, and gene sequence data showed Licmosphenia sister to the few available Licmophora spp. Two questions remain: (1) what is the structure of Licmosphenia spp. with fine striae? and (2) what would further molecular evidence contribute to understanding whether these genera are distinct or not? New LM and SEM observations on Licmosphenia species and sequence data from additional Licmophora species now answer these questions. Valve ultrastructure of a new, finely striated species with a small apical aperture, from Mallorca, Spain, is similar to finely striated Licmophora species, and the position of Licmosphenia in the phylogenetic tree is now within the Licmophora clade. The presence of apical apertures in two morphological groups of Licmophora suggests that the apical window has arisen at least twice. Licmophora is the older genus name and we therefore formally transfer all Licmosphenia species to it. In addition to Licmophora garyi from Mallorca, we describe a curved species from the Adriatic, Licmophora arcuata, similar to L. grunowii but with much coarser striae, and a species from Guam with a very large apical aperture, L. pisciformis. We also designate an epitype for Licmosphenia clevei Mereschkowsky, the type species of that genus. © 2015 The International Society for Diatom Research. Source

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