Cultural evidence for the morphologic plasticity of Entophysalis deusta (Meneghini) Drouet and Daily (Chroococcales, Cyanophyceae) W.F. Prud’homme+van+Reine andC. van den Hoek 1. INTRODUCTION Drouet and Daily (1956) in their revision of the coccoid Myxophyceae, unite under often Entophysalis deusta (Meneghini) Drouet and Daily a number of recorded marine littoral rock-inhabiting and lime-penetrating Cyanophyceae, such as Gloeocapsa crepidinum Thur. ex Born. & Thur. (traditionally Chroococcaceae), Entophysalis granulosa Ktitz. (traditionally Chroococcales, Entophysalidaceae), Pleurocapsa fuliginosa Hauck (traditionally Pleurocapsales, Pleurocapsaceae), Hyella caespitosa Born. & Flah., Hyella balani Lehmann (traditionally Pleurocapsales, Hyellaceae). In all Drouet and Daily synonymize 100 specific nomenclatural and infraspecific names with E. deusta. Of these, 22 are synonyms, so 78 putative taxa belong, according to these revisers, to one species. However, the large of these are used majority names never in recent publications on cyanophycean taxonomy. In Parke and Dixon's 'Revised check-list of British marine algae' (1964) 8 marine be deusta Chroococcales are enumerated that should ranged under Entophysalis according to the taxonomic concepts ofDrouet and Daily. 2. MATERIAL AND METHODS with Old oyster-shells, infected various species of perforating algae, were collected near Wemeldinge (Oosterschelde, Netherlands). These shells appeared to contain ‘Hyella caespitosa’ filaments. In order to kill algae growing attached to the surface these shells were scrubbed and about seconds. of such shells dipped in 50 % aethanol during 5 to 10 Fragments were subsequently cultured in culture tubes containing Erdschreiber-chalk-agar covered by a thin layer of Erdschreiber. After weeks characteristic colonies to mm 6 blackish-green gloeocapsoid (c. 1 3 in had the surface of the of other diameter) appeared on agar (fig. 1), among a number perforating algae. Unialgal cultures were isolated from the above gloeocapsoid colonies and grown in tubes with Erdschreiber-chalk-agar covered by a thin layer ofErdschreiber. After colonies had of which small 3 weeks typical gloeocapsoid appeared, to a part of were added. The transparant fragments oyster-shells Erdschreiber-chalk-agar was of 11 and chalk. prepared from a mixture Erdschreiber, 18 g agar 10—20 g For preparation of Erdschreiber, cf. Dammann, 1930. other best with thin Entophysalis-colonies (not the perforating algae!) grew on agar a of fluid that and top layer (Erdschreiber) subsequently disappeared by evaporation absorption by the agar. Growth on agar without a fluid top layer orwith too much fluid was clearly much smaller. and The cultures were kept in culture rooms of 20° C and 12° C in daily 18 hours' BLUMEA VOL. No. 278 XIV, 2, 1966 colonies from aethanol treated cells. — Fig. I. Gloeocapsoid grown directly Figs. 2—4. Unialgal Entophysalis-like colonies, fig. 4 with Hormathomena-like cells (unilateral thickening of sheath). — Colonies with of Thick-lined cells Figs. 5 24. grown in contact fragments oyster-shell. growing outside the shell, thin-lined cells growing inside the shell. The penetrating cells form Hyella-like filaments. — shell 5 23 surface views, fig. 24 cross-section of with Hyella-like filaments. The different did have influence photoperiods. two temperatures not any appreciable on the results. in Plants growing the transparantfragments of shells were directly observed under the Hoek 279 W. F. Phud'homme van Reine & C. van den : Plasticity of Entophysalis deusta For legends see facing page. Some were decalcified with a solution of Na -EDTA microscope. fragments 5 % 2 (ethylenediaminetetraacetic acid, disodium salt) in Erdschreiber. After two days the of such fragments were decalcified and the cyanophyte was still living. Cross-sections fragments were made by hand with a razor-blade. AND 3. RESULTS DISCUSSION colonies aethanol treated shells. The 1. Morphology of grown directly from blackish-green, showed the shining colonies, macroscopically as well as microscopically, typical mor- of phology of ‘Gloeocapsa crepidinum’ (fig. 1). Gelatinous irregular colonies rounded or mutually flattened cells, surrounded by colourless, not obviously lamellatedsheaths. Cell- divisions in all directions. Cells oftenseemingly in groups oftwo or four (in surface view). ' Transitions Diameterof cells to ‘Entophysalis granulosa’ are present. 4—15 /*. 280 13LUMEA VOL. XIV, No. 2, 1966 2. Morphology of unialgal cultures growing on agar and isolated from material described under under 3.1. Macroscopical aspect as 3.1. Partly resembling ‘Gloeocapsa crepidinum’, ' partly ‘Entophysalis granulosa’, both aspects merging into each other. Cell-divisions in all directions, but with a preference for the direction perpendicular to the surface, as a result of which the cells are arranged in vertical cellrows. Lamellation of the sheaths obvious than under The sheaths often devel- more 3.1. quite unilaterally more to cells similar to ‘Hormathonema’ oped giving rise or cell-groups ' spp. (cf. Ercegovic, Geitler The 1929 b, 1930—32) (fig. 4). ‘Entophysalis granulosa’ '-aspect is the characteristic result of crowding in well-growing cultures. In nature old crusts of the 'black zone' of this of the upper intertidal belt exhibit aspect. Diameter cells 2.5—10 /i (fig. 2 —4). colonies contact with Such colonies 3. Morphology of grown in fragments of oyster-shells. reacted in accordance with Drouet and Daily's description of Entophysalis deusta by of basal the forming a profusion filaments penetrating into shell-fragments (fig. 6—24). Such filaments from from isolated arise ‘Gloeocapsa’-like cell-groups (fig. 17, 22, 23, 24) or cells The (fig. 14, 18, 19, 21, 24). filaments show true branching, but often they are The filaments lamellation. unbranched. sheaths of the penetrating do not have an obvious be inside the The filaments Gloeocapsoid cell-groups may also found shell. penetrating of The are sometimes composed two to several cell-rows. penetrating phase is identical with forms described as Hyella caespitosa and H. balani. Particularly cells or cell-groups initial Geitler with perforation cover Pleurocapsa minuta (1930—32, p. 355) (fig. 6, 7, 8, 13, 14). Conclusions and results the 4. discussion. These support concept of Entophysalis deusta as a morphologically highly plastic cyanophyte, whose different morphological possibili- ties are often encounteredin the literature as Gloeocapsa crepidinum, Entophysalis granulosa, Pleurocapsa fuliginosa, and Hlyella caespitosa. Results ofinvestigations of naturally occurring accordance with material are in this opinion (cf. Koumans-Goedbloed, 1966; van den Hoek, 1958; personal experience of the second author). Drouet and Daily, in their 'Revision of the coccoid Myxophyceae reduce a number ’, of about 2800 the nomenclatural total of taxa. names (including synonyms) to a 32 the other Geitler, on hand, in his compilatory work on the Cyanophyceae (1930—32) which serves as an identification work for the more traditionally thinking algologists, this recognizes 322 species as belonging to group. Drouet and revision much of Daily's provoked criticism, part which very severe These authors' (Bourrelly, 1957; Geitler, i960; Skuja, 1956). two comparative investiga- tions of and documentation large numbers of dried specimens are considered naively uncritical As ('naivste Kritiklosigkeit') (Geitler). to Entophysalis deusta we do not agree with and of this better founded and Geitler, since Drouet Daily's concept species is entities it documented than those of the synonymous with and described in the general compilation works. However, one can admit that a more exhaustive treatment of the taxonomic principles underlying their work and figures illustrating their viewpoints would have facilitated a more constructive discussion. The above reviewers criticize Drouet and Daily for not having investigated living populations, because the taxonomically valid characters can only be observed in living material (in fact the authors investigated much living material, particularly from the United The used to differentiate this States). criteria traditionally in group are: a) structure of thallus in form (unicellular, multicellular, rows or not so, branched or not so, etc.), b) of mode of formation of cells, c) cell-division, d) nannocvtes or endospores, e) structure W. F. Prud'homme van Reine & C. van den Hoek: Plasticity of Eiitophysalis deusta 281 and colour of absence of sheaths, f) dimensions, g) presence or gas vacuoles, h) habitat (epiphytic, endolithic, epilithic), i) colour of cell-contents. Of these criteria only the last to be much modified dried used one is apt in material. In practice, it is as a criterion of Further dried minor importance. many cyanophycean specimens survive long periods. of the of deusta teated 26 102 synonyms Entophysalis are in Geitler's compilation, namely 1) Entophysalis granulosa Kiitzing 1843, 2) Gloeocapsa crepidinum Thuret 1876, 3) Dermocarpa violacea Crouan fr. 1858, 4) Placoma vesiculosa Schousboe & Thuret in Hauck Bornet & Thuret 1876, 5) Pleurocapsa fuliginosa 1885, 6) Hyella caespitosa Bornet Flahault & 1888, 7) Hyella caespitosa var. spirorbicola Hansgirg 1892, 8) Aphanocapsa littoralis Hansgirg 1892, 9) Hyella caespitosa var. nitida Batters 1896, 10) Pleurocapsa Collins halani Lehmann littorinae crepidinum 1901, n) Hyella 1903, 12) Hyella Setchell & Gardner 1918, 13) Placoma violacea Setchell & Gardner 1918, 14) Pleurocapsa entophysaloides Setchell & Gardner