Species of uncertain affinities currently assigned to Glenodinium Genus 1. Glenodinium Ehrenberg 1836, p. 174 Type species: Glenodinium cinctum Ehrenberg 1836 The genus Glenodinium was described in a very incomplete way by Ehrenberg in 1836. In the following decades the name G. cinctum was used in most works dealing with freshwater dinoflagellates, sometimes accompanied by descriptions and illus- trations which differed considerably from one another. The generic name has been used with criteria that varied more extensively over the years than for any other dinoflagellate genus. For many authors throughout the twentieth century the name was applied on the basis of the negative character of not having visible structure on the theca (Meunier 1919), despite the definition of the genus based on a range of tabulations in Schiller’s (1935a) monographic treatment in Rabenhorst’s Kryp- togamen-flora. When Wołoszyńska (1916) described the genus Sphaerodinium, she concluded, after publication of her paper, that it was identical to Glenodinium and that her species Sphaerodinium limneticum was identical to Glenodinium cinctum (Wołoszyńska 1917). Instead of transferring her species of Sphaerodinium to the older genus Glenodinium, she did the opposite and transferred Ehrenberg’s Gleno- dinium cinctum to Sphaerodinium. This resulted in confusion and the exclusion of the type species from the genus Glenodinium in most identification manuals. Most species below will undoubtedly be transferred to other genera, and the identity of the type species will have to be resolved. Because of their very thin amphiesmal plates, species of this group occupy an intermediary position between the “naked” gymnodinioids and the heavily “armored” peridinioids and gonyaulacoids. Some may prove to be peridinioids, other are perhaps woloszynskioids. Key to species of uncertain affinities currently referred to Glenodinium: 1a Cells with eyespot .......................................................................................... 2 1b Cells without eyespot ................................................................................... 10 2a Eyespot horseshoe-shaped or triangular ......................................................... 3 2b Eyespot comma-shaped or round ................................................................... 5 3a Eyespot horseshoe-shaped ������������������������������������������������������������������������������ 4 3b Eyespot triangular ............................................................ 2. G. amphiconicum 4a Cells dorsoventrally strongly compressed ���������������������������������� 7. G. gessneri 4b Cells barely compressed dorsoventrally ......................................1. G. cinctum 5a Chloroplasts present, sulcus does not extend to apex ..................................... 6 5b Chloroplasts absent, sulcus extends to apex ......................10. G. leptodermum 6a Chloroplasts blue-green or glaucous ..........................................8. G. glaucum 6b Chloroplasts yellow or brown ������������������������������������������������������������������������ 7 © Springer-Verlag GmbH Deutschland, ein Teil von Springer Nature 2018 Ø. Moestrup, A. J. Calado, Süßwasserflora von Mitteleuropa, Bd. 6 – Freshwater Flora of Central Europe, Vol. 6: Dinophyceae, Süßwasserflora von Mitteleuropa, https://doi.org/10.1007/978-3-662-56269-7 454 Species of uncertain affinities currently assigned to Glenodinium 7a Cells strongly compressed dorsoventrally ���������������������������������� 7. G. gessneri 7b Cells not or only slightly compressed dorsoventrally ..................................... 8 8a With numerous chloroplasts ........................................................................... 9 8b With few large rounded chloroplasts, cells shaped as a parallelogram ............. ...................................................................................................13. G. peisonis 9a Cingulum slightly descending, sulcus forms circular area on epicone ............. .................................................................................................17. G. segriense 9b Cingulum circular, sulcus forms very slight indentation on epicone ���������������� ..........................................................................................18. G. vindobonense 10a Edges of the sulcus terminate in antapical tooth .................4. G. denticulatum 10b No teeth at the antapical end of the sulcus edges ..........................................11 11a Cells disc-shaped .......................................................................................... 12 11b Cells may be slightly compressed dorsoventrally but not disc-shaped ......... 13 12a Cells very flat, posterior end flat, undulated, cell 46 µm long; in eutrophic ponds ............................................................................................. 11. G. limos 12b Cells ca. 14 µm thick and 32 µm long; in acid bogs ...................... 12. G. mezii 13a Chloroplasts absent.............................................................16. G. punctulatum 13b Chloroplast present ....................................................................................... 14 14a Epicone narrower than hypocone ........................................... 3. G. dangeardii 14b Epicone as wide as or wider than hypocone ................................................. 15 15a Epicone wider than hypocone (overhanging) .......................15. G. pulvisculus 15b Epicone as wide as hypocone (occasionally hypocone wider) ��������������������� 16 16a Epicone with apical pore ........................................... 14. G. pseudostigmosum 16b No apical pore .............................................................................................. 17 17a With numerous chloroplasts ......................................................................... 18 17b With two chloroplasts, one at each end ................................ 6. G. eurystomum 18a Cell with wide indentation at the right anterior end ............5. G. emarginatum 18b Apical end without emargination ................................................................. 19 19a Cells 20–24 µm long, sometimes less ................................... 9. G. helicozoster 19b Cells 30–40 µm long ................................................................17. G. segriense 1. Glenodinium cinctum Ehrenberg sensu auctorum (Fig. 404) Glenodinium cinctum Ehrenberg 1836, p. 174; Ehrenberg 1838, p. 257, pl. XXII, fig. XXII ≡Peridinium oculatum Dujardin 1841, p. 374 ≡ Peridinium cinctum (Eh- renberg) Claparède & J. Lachmann 1859, p. 404, nom. illeg. (non Peridinium cinc- tum (O. F. Müller) Ehrenberg) Glenodinium berghii Lemmermann 1900b, p. (117) (Glenodinium cinctum sensu Bergh 1881, pp 247, 248, 251, figs 65–67) Cells ovoid to subspherical, epi- and hypocone of approximately equal size. Epi- cone hemispherical to rounded conical, hypocone rounded conical. Cingulum cir- cular, sulcus does not extend into the epicone. Cells yellow, with smooth theca. Large horseshoe-shaped eyespot. Ehrenberg (1838) indicated the size as 47 µm; his illustrations show a range of 33–53 µm in length, width 33–50 µm, thickness 30 µm. Variants by subsequent authors include differences in relative length of the epi- and hypocone and a differently shaped, or even absent, eyespot. Ecology: mesotrophic to eutrophic ponds, more rarely in lakes (Lemmermann 1910). Geographical distribution: Germany. Genus 1. Glenodinium 455 b d g a c f e h Fig. 404 Glenodinium cinctum Ehrenberg (a–f after Ehrenberg 1838; g, h after Bergh 1881). a, b ventral views; c dorsal view; d, e right lateral views; f cell division?; g emp- ty theca seen from the dorsal side; h recently divided cells within mucilage of division cyst 2. Glenodinium amphiconicum J. Schiller 1955, p. 49, pl. IX, fig. 49 (“ampliconicum”) (Fig. 405) Cells biconical, slightly flattened dorsoventrally. Epi- and hypocone of almost equal size. Sides straight or slightly concave when seen from the ventral side, the cells thereby acquiring the appearance of a parallelogram. Cingulum barely de- scending. Sulcus on hypocone only, deeper in front, more flattened posteriorly. With numerous yellowish-brown chloroplasts, shaped as oval plates. The number of chloroplasts varies with the season, fewer in spring, more in summer and au- tumn. Eyespot almost triangular, located in the anterior part of the sulcus, anterior edge of the eyespot slightly concave. Thin cell cover present. Cells 28–30 µm long, 24–26 µm wide. Ecology: Lake Neusiedl, Austria, May–October 1951. Geographical distribution: Austria. ac dfg be Fig. 405 Glenodinium amphiconicum J. Schiller (after Schiller 1955). a, b ventral and dorsal views; c, d ventral views with triangular eyespot; e vertical view; f round protoplast retracted inside enlarged cell cover; g biconical cell 456 Species of uncertain affinities currently assigned to Glenodinium ab d c e Fig. 406 Glenodinium dangeardii Lemmermann (after Dangeard 1888). a ventral view; b, c cell division in immotile stage before and after liberation of daughter cells, respectively; d immotile cell surrounded by a thick layer of mucilage; e resting cyst 3. Glenodinium dangeardii Lemmermann 1910, p. 634, figs 37–40 (p. 580) (Fig. 406) Glenodinium cinctum sensu Dangeard (1888, pp 127, 128, pl. V, figs 1–5) Epicone hemispherical, smaller than the conical hypocone which is rounded at the antapex. Cingulum circular. Sulcus extends to the antapex, and slightly onto the