18 – EUNOTIOID AND ASYMMETRICAL NAVICULOID DIATOMS

I. INTRODUCTION

In this chapter, we discuss the diverse assemblageof asymmetric diatoms that lack a keel. Grouping thesetaxa is a matter of convenience, because asymmetryabout the apical or transapical axis has evolved in various lineages (Kociolek and Stoermer, 1988c,1993a). Asymmety has arisen several times over evolu-tionary history as an adaptation to a stalked, or sessile,existence. Only recently have diatomists made explicithypotheses about convergent evolution of charactersand the extent to which members of these groups arephylogenetically distant taxa. Symmetry is generallyunreliable for diagnosing natural groups, yet the oldertaxonomic literature relied heavily on symmetry fea-tures (e.g., Bessey, 1899; Karsten, 1928; Hustedt, 1930;Patrick and Reimer, 1966, 1975), and features of asym-metry may still be helpful in identification.

Five families and 14 genera are considered here.Taxonomic differentiation is based on the number andorganization of the plastids, features of the nucleus andpyrenoids (Geitler, 1932; Round, et al., 1990, Cox1996), methods of sexual reproduction (Geitler, 1932,1973a), valve morphology, growth habits, and ecologi-

cal breadth. Due to their widespread distribution anddominance in many habitats, eunotioid and asymmetri-cal naviculoid diatoms have been the focus of valveultrastructural studies (Hasle, 1973; Dawson, 1972,1973a–c, 1974; Cox, 1996; Gaul et al., 1993). Still,less than 5% of most diatom taxa have been studiedfrom an ultrastructural point of view.

Members of these groups have been useful in environmental applications, such as paleolimnologicalreconstructions and as indicators of water quality(Patrick et al., 1954; Smol, 1990). However, this groupalso includes forms acknowledged to pose some of themost vexing taxonomic problems, such as the speciesidentification of many Eunotia and Gomphonema.

Patrick and Reimer (1966, 1975) have provided a foundation of North American taxa on which to doc-ument and understand diversity of these groups. Latermonographs or concentrated taxonomic work on thefollowing genera have been accomplished using wholly, or based in part on, North American speci-mens: Actinella (Kociolek et al., 1997), Gomphonema(e.g., Kociolek and Stoermer, 1987b, 1991; Kociolekand Kingston, 1999; Reichardt, 1999), Gomphoneis(Kociolek and Rosen, 1984; Kociolek and Stoermer,

655

18EUNOTIOID AND ASYMMETRICALNAVICULOID DIATOMS

J. P. Kociolek, S. A. SpauldingDiatom CollectionCalifornia Academy of SciencesGolden Gate ParkSan Francisco, California 94118

I. IntroductionII. Diversity and Morphology

A. EunotiaceaeB. CatenulaceaeC. CymbellaceaeD. GomphonemataceaeE. Rhoicospheniaceae

III. Ecology and DistributionA. Physical Factors

B. Chemical FactorsC. Biotic Factors

IV. Key and Descriptions of North AmericanGeneraA. KeyB. Descriptions of Genera

V. Guide to Literature for SpeciesIdentification

Literature Cited

Freshwater Algae of North AmericaCopyright © 2003, Elsevier Science (USA). All rights of reproduction in any form reserved.

1986, 1988a, b), Cymbella (Krammer, 1982, 1997a, b), and Reimeria (Kociolek and Stoermer, 1987a).

The following classification is proposed for thegenera considered herein:

BacillariophyceaeNaviculales

EunotiaceaeAmphicampa (Ehrenberg) Ralfs in PritchardActinella LewisEunotia EhrenbergPeronia Brébisson et Arnott ex KittonSemiorbis Patrick in Patrick et Reimer

CatenulaceaeAmphora Ehrenberg ex Kützing

CymbellaceaeCymbella C. A. AgardhDidymosphenia M. SchmidtEncyonema KützingReimeria Kociolek et Stoermer

GomphonemataceaeGomphoneis CleveGomphonema Ehrenberg

RhoicospheniaceaeGomphosphenia Lange-BertalotRhoicosphenia Grunow

II. DIVERSITY AND MORPHOLOGY

A. Eunotiaceae

The Eunotiaceae is an unusual and morphological-ly heterogeneous group. In earlier literature, this familywas referred to as rhaphidioid diatoms (Hustedt, 1926,1952), due to the peculiar orientation of the raphe system. The proximal raphe ends and most of thelength of the raphe are found on the valve mantle; onlythe distal raphe ends may extend onto the valve face.An exception to this arrangement occurs in Peronia,(Fig. 1E), in which the raphe system is positionedeccentrically on the valve face.

Of the raphe-bearing diatoms, the Eunotiaceae isthe only group with one or more rimoportules. Thesestructures are slitlike openings in the valve, with inter-nally thickened edges. In much of the older literature,rimoportules are termed labiate processes, or jellypores. Rimoportules are also present in centric and ara-phid diatoms and are thought to be a primitive feature.Rimoportules have also been suggested to be homolo-gous to the raphe system itself (Hasle, 1973). Becauseof the possession of both rimoportules and a raphe,eunotioid diatoms are thought to constitute an evolu-tionary intermediate, between the primitive araphidsand more advanced raphe-bearing groups (Hustedt,1926, 1952).

Cells may grow singly, in filaments, or at the endsof short stalks, attached to a variety of substratumtypes. Several members of the group have prominentspines around the periphery of the valve, whereas others (e.g., Semiorbis) have deep ridges running trans-versely across the valve. Within the family, the mostdiverse genus by far in terms of number of species isEunotia (Van Landingham, 1969). Eunotia and itsclose allies (e.g., Actinella, Amphicampa) characteristi-cally have a valve face traversed by striae and inter-rupted close to the ventral margin (e.g., Fig. 1A–C). Allother genera are relatively small, from the monotypicSemiorbis to genera with only several taxa in the NorthAmerican flora. Only one species of Actinella is reported from North America. Peronia, a relativelyrare genus, possesses a raphe on the valve face, whichis displaced to one side (Fig. 1E). The valve of Peroniaalso includes a central sternum (an unornamented areaor rib of silica running the length of the valve).Vyverman et al., (1998) have described a unique genuswithin the Eunotiaceae, with valve and symmetry features similar to Amphora. This genus, namedEunophora, is an endemic of Tasmania and has no representatives from North America (Vyverman et al., 1998).

B. Catenulaceae

Catenulaceae is represented by the genusAmphora, a widely distributed genus encompassing abroad spectrum of morphology. Members of Amphorashare an eccentrically placed raphe system, which islocated toward the ventral margin of the valve(Fig. 2G–I). The ventral mantle is distinctly more shal-low than the dorsal mantle. The position of the rapheand height of the ventral and dorsal mantles form afrustule that is highly adapted to grow on the curvedsurfaces of aquatic macrophytes. Amphora is represent-ed by fewer than 25 known species in the NorthAmerican flora (Stoermer and Yang, 1971; Patrick andReimer, 1975). Kingston et al., (1980) discussed differ-entiation of the genus from Cymbella.

C. Cymbellaceae

Members of the Cymbellaceae are asymmetricalabout the apical axis and herein include Cymbella,Encyonema, Reimeria, and Didymosphenia. Severaladditional genera have been subdivided out of Cymbellaand Encyonema (Krammer, 1997a, b). Reimeria,Cymbella, and Didymosphenia bear apical pore fields,(specialized pores, differentiated in size or positionfrom areolae) (Fig. 2). Apical pore fields of these gen-era are not bisected by the external distal raphe ends.

656 J. P. Kociolek and S. A. Spaulding

18. Eunotioid and Asymmetrical Naviculoid Diatoms 657

FIGURE 1 (A)–(C) Eunotia spp., the apical axis is asymmetrical and the transapical axis is symmetrical (A)Eunotia faba; (B) Eunotia sp.; (C) Eunotia serra; (D) Semiorbis hemicyclus, valves are highly arched and lackundulations; (E) Peronia fibula; on one valve the raphe is short and straight and a rimoportule is present nearthe apex; the other valve lacks a raphe, or it is only rudimentary; (F) Actinella punctata, valves are distinctlysymmetrical to the apical and transapical axes; (G) Amphicampa eruca, both dorsal and ventral margins aredistinctly undulate. Scale bars equal 10 μm. Scale bar in (A) applies to (A)–(G); except where marked in (E).


FIGURE 2 (A)–(C) Cymbella spp., valves are slightly to strongly asymmetrical to the apical axis and symmet-rical to the transapical axis (A) Cymbella proxima; (B) Cymbella turgidula; (C) Cymbella affinis; (D)Didymosphenia geminata, valves are markedly large and robust, and the apical pore field is not bisected by theraphe; (E), (F) Encyonema spp., the distal raphe ends are ventrally deflected (E) Encyonema muelleri; (F)Encyonema minuta; (G)–(I) Amphora spp., the frustules are markedly wedge-shaped (G) Amphora sp.; (H)Amphora pediculus; (I) Amphora perpusilla; (J), (K) Reimeria taxa, the dorsal margin is slightly arcuate,whereas the ventral margin is straight to slightly concave, and tumid at the central area (J) Reimeria sinuata f.antiqua; (K) Reimeria sinuata. Scale bars equal 10 μm. Scale bar in (B) applies to (B)–(K); except wheremarked in (A) and (D).

Discovery of evolutionary convergence in asymme-try has led to changes in classification of some genera(Kociolek and Stoermer, 1988c; Kociolek, 1998). BothCymbellaceae and Gomphonemataceae possess asym-metry about the transapical axis, as well as similaroverall valve morphology. Also, both families containgenera with apical pore fields. However, within theGomphonemataceae, apical pore fields are bisected bythe distal raphe. Cladistic analysis of cytologic andother morphologic characters showed evolutionaryparallelism between Didymosphenia and the Gompho-nemataceae (Kociolek and Stoermer, 1988c). Thus,Didymosphenia is now considered to be a member ofthe cymbelloid diatoms, rather than its previous inclu-sion with gomphonemoid taxa.

Stigmata (isolated perforations at the center of thevalve that have rounded external openings but slitlikeinternal openings) are also common in all four genera.These structures may be variable with respect to size,placement, and internal structure. In both Cymbella-ceae and Gomphonemataceae, a phylogenetic relation-ship exists between the position of stigmata, externaldistal raphe ends, nucleus, and pyrenoid (Geitler, 1981;Kociolek and Stoermer, 1988c). In taxa where the stigma is dorsal, the nucleus is also dorsally placed.These taxa also possess a ventral pyrenoid and ventraldeflection of the distal raphe ends (as in Encyonema;dorsal and ventral being determined by the curvatureof the valve outline). In other taxa (e.g., Cymbellasensu stricto, Didymosphenia) stigmata are ventral, the nucleus is ventral, the pyrenoid is dorsal, and theexternal distal raphe ends are deflected dorsally.

Cymbella is the most diverse genus within theCymbellaceae in terms of number of species (Krammer,1982, 1997a, b). Diversity within Reimeria andDidymosphenia has been masked more by a lack ofdetailed taxonomic work than by a lack of variation(Skvortzow and Meyer, 1928; Sala et al., 1993;Metzeltin and Lange-Bertalot, 1995).

D. Gomphonemataceae

The Gomphonemataceae appears to be a naturalgroup, diagnosed by several shared, derived features(Kociolek and Stoermer, 1988c, 1993a). Most speciesproduce stalks of mucopolysaccharides, which aresecreted through the apical pore field. Stalks form anattachment to benthic substrata, and dense aggregationsof vegetative clones are often visible to the naked eye.

Both Gomphoneis and Gomphonema are well-represented genera in the North American flora. Aremarkable aspect of the North American flora is thediversity and geographic distribution of Gomphoneis.Within the G. herculeana species complex (Kociolek

and Stoermer, 1988a), several large taxa may be abundant in freshwater diatom communities in westernNorth America, the Laurentian Great Lakes, and thesoutheast United States. Gomphoneis as originally construed (i.e. the doubly punctate species with longi-tudinal lines) is not a monophyletic group (Cleve,1894; Kociolek and Rosen, 1984; Kociolek andStoermer, 1988c). The Gomphoneis herculeana speciescomplex, with true stigmata and bilobed apical porefields, is more closely related to Gomphonema than tothe other species complex in Gomphoneis (Kociolekand Stoermer, 1993a). This second species complex, theGomphoneis elegans group, has stigmoids instead ofstigmata and condensed striae instead of apical porefields at the footpole. Some astigmate species may alsooccur in the G. elegans group.

Gomphonema is a large genus, with over 400 taxa(Van Landingham, 1978) and worldwide distribution.Within North America, it is common and diverse.Gomphonema species may be astigmate or bear stig-mata. Morphology has been well documented with thescanning electron microscope for some species (e.g.,Dawson, 1972, 1973c), but the diversity of the genus isjust now being revealed. Heterogeneity is becomingmore widely known with respect to the presence orabsence of stigmata. Furthermore, the structure of stigmata, type of areolar occlusions, and structure andposition of apical pore fields are variable in form.Taxonomic and morphological diversity in NorthAmerica is becoming more apparent (Lowe andKociolek, 1984; Kociolek and Stoermer, 1991;Kociolek et al., 1995; Kociolek and Kingston, 1999;Reichardt 1999).

E. Rhoicospheniaceae

The Rhoicospheniaceae is a group of freshwaterand marine taxa, with only two genera in fresh watersof North America. Rhoicosphenia has many distinctivefeatures, including flexed valves and one valve withvery small raphe branche (Fig. 3I–K). The genus alsoshares some features with members of the Cymbella-ceae and Gomphonemataceae, including type of sexualreproduction, organization of cytoplasmic organelles,stalked growth form, and, with the Gomphonemata-ceae, presence of pseudosepta. A single extant species isfound in fresh waters in North America, R. abbreviata(known until relatively recently as R. curvata). Thenomenclature (Lange-Bertalot, 1980) and morphology(Mann, 1982a, b) of the genus have been documented.

Gomphosphenia lacks stigmata, apical pore fields,septa, and pseudosepta while having characteristicanchor-shaped internal proximal raphe ends (Fig. 3L).Besides its asymmetry about the transapical axis, it



FIGURE 3 (A)–(E) Gomphonema spp., a single stigma is usually present on one side of the central area andlongitudinal lines are absent (A) Gomphonema sphaerophorum; (B) Gomphonema truncatum; (C)Gomphonema sp.; (D) Gomphonema acuminatum; (E) Gomphonema apuncto; (F)–(H) Gomphoneis (F)Gomphoneis olivacea, stigmoids number 0–4, longitudinal lines are absent, and striae are composed of indis-tinct puncta; (G) Gomphoneis eriense var. variabilis, valves possess stigmata, longitudinal lines, and doublypunctate striae; (H) Gomphoneis minuta var. lowei.; (I)–(K) Rhoicosphenia curvata, the concave valve possessesa raphe that extends almost the length of the valve; the convex valve possesses short raphe branches nearapices; (L) Gomphosphenia lingulataeforme. Scale bar equal 10 μm, applies to (A)–(L).

appears to be distantly related to Gomphonema andGomphoneis. Gomphosphenia includes a taxon citedin older literature as “Gomphonema brasiliense” (e.g., Wallace, 1960; Patrick and Reimer, 1975) and G.grovei (Kociolek et al., 1988). The former, now knownas Gomphosphenia lingulataeforme, has been reportedalmost exclusively from eastern North America(Kociolek and Kingston, 1999). Gomphospheniagrovei is found mostly as a fossil in western NorthAmerica and occurs elsewhere only rarely.

III. ECOLOGY AND DISTRIBUTION

Given the diversity of phylogenetic lineages andforms found in the group of diatoms dealt with in thischapter, it is difficult to generalize about ecological dis-tributions, especially at the level of genus. These formsall possess a raphe system, assume a variety of growthforms, and occur on a wide range of substratum types.Like the symmetrical naviculoid diatoms, they occur inlentic, lotic, and aerophilic habitats. Much of the litera-ture on the distribution of freshwater diatoms in NorthAmerica is now dated (Patrick and Reimer, 1966).Cholnoky (1965) covered a wide range of topics con-cerning the interplay of ecology and diatom distribu-tions. Lowe (1974) provides a summary of ecologicalpreferences and tolerances for selected freshwater taxa, based on literature reports. Krammer and Lange-Bertalot (1986, 1991) provide a wide range of summa-ry information for specific taxa considered in theirfloristic study of the diatoms of central Europe.

A. Physical Factors

Members of the Eunotiaceae may be cosmopolitan(e.g., Eunotia praerupta) or narrowly restricted in geographic distribution. For example, E. papilio is con-sidered circumboreal (Krammer and Lange-Bertalot,1991), and Actinella punctata is found across easternNorth America and Scandinavia (Kociolek et al.,1997). Other species from eastern North America areknown only from their type localities (Patrick, 1958).Some Eunotia species have been reported from specifictypes of physical habitat types, including some fromstrictly flowing or still waters (E. formica) (Foged,1948). Other Eunotia species have also been character-ized as being aerophilic (E. pectinalis var. minor)(Manguin, 1952).

Within the Catenulaceae, species are usually benthic and are found in swamps, wetlands, lakes, andlarge rivers with slow-moving currents. Some taxa arelimited to alpine or colder regions (Krammer andLange-Bertalot, 1986), including the upper Great Lakes

(Stoermer and Yang, 1971). For example, Amphoracalumetica is restricted to the upper Great Lakes(Patrick and Reimer, 1975; Edlund and Stoermer,1999).

Members of the Cymbellaceae are widely distrib-uted in freshwater ecosystems, including both lakes andrivers. A few taxa have been reported exclusively from either lentic (e.g., Cymbella lata, C. cymbiformisAgardh, C. proxima, C. cistula) habitats or lotic (e.g.,C. turgidula) habitats (Cholnoky, 1965; Patrick andReimer, 1975). The group is found across a broad tem-perature spectrum, but some species seem restricted tocool-water environments, such as Didymosphenia geminata and Encyonema norvegica (Patrick andReimer, 1975).

Members of the Gomphonemataceae are character-ized by their eurytolerance of flow conditions. Someforms (e.g., Gomphonema gracile) have been character-ized as being lake forms (Hustedt, 1930; Foged, 1954)whereas others are considered to be rheophils (e.g., G.parvulum) (Foged, 1948, 1954; Patrick and Reimer,1975). At times, some taxa are found in the planktonof lakes. Cells may grow individually or form massivebenthic colonies that blanket any available substrate.

Although many species are considered to be cos-mopolitan in distribution (e.g., G. parvulum and G.angustatum, among others) some are restricted to specific regions. For example, G. hebridense is confinedto the northern hemisphere (Krammer and Lange-Bertalot, 1986). Gomphonema apuncto and G.manubrium are known exclusively from the east coastof North America (Patrick and Reimer, 1975; Kociolekand Kingston, 1999), whereas other species are knownfrom single localities in the United States (Patrick andReimer, 1975; Reichardt, 1999).

Rhoicosphenia is common in lotic ecosystems oralong the shores of lakes. It is found across a widerange of nutrient and other chemical regimes.

B. Chemical Factors

The Eunotiaceae grow across the spectrum ofhydrogen ion concentration (pH), whether the habitatsare bogs rich in humic acids, drainages of the Atlanticcoastal plain, or clear lakes acidified by natural oranthropogenic sources. Certain species, such as E.exigua have been reported from habitats with pH values as low as 2–3. Others are found in circum-neutral or even slightly alkaline waters, whereas somemay be indifferent to pH (Lowe, 1974). Within thegenus Eunotia, species show a range of tolerance ofnutrient concentrations and organic contaminants. Somespecies are restricted to oligotrophic waters (Patrickand Reimer, 1966; Krammer and Lange-Bertalot,


1991), and others, such as E. ruzickae, are character-ized as preferring eutrophic waters. Eunotia septentri-onalis is known to occur in habitats with high sulfatelevels (Krammer and Lange-Bertalot, 1991).

Amphora, of the Catenulaceae, is most commonlya benthic, marine form. In fresh water, some species ofAmphora are found in circumneutral to alkaline waters,often in habitats with high ionic concentrations (Krammerand Lange-Bertalot, 1986; Round et al., 1990). Otherspecies are found only in very dilute, oligotrophic conditions. Cholnoky (1965) reports that A. inflata isfound in waters with high oxygen concentrations.

The Cymbellaceae are often characterized as occur-ring in circumneutral fresh waters across a wide spec-trum of nutrient concentrations and water chemistries.Yet, at the species level, habitat preferences becomemore apparent. Encyonema helvetica, C. aspera and D. geminata grow in oligotrophic waters. Reimeria sinuata was reported as having a pH optimum of 8(Cholnoky, 1965), and C. cesatii occurs in acid waters(Patrick and Reimer, 1975). Cymbella amphicephalaand E. microcephala are reported from high oxygenhabitats (Krammer and Lange-Bertalot, 1986).Cymbella pusilla Grunow is tolerant of relatively highlevels of specific conductance and may grow in abun-dance in estuaries (Patrick and Reimer, 1975).

In the Gomphonemataceae, most species are foundacross a wide range of pH values, but the group mightbe best characterized as being circumneutral. Severalspecies have been reported to be alkaliphilous, includ-ing Gomphonema acuminatum var. brebissonii, G.angustatum, and G. abbreviatum (Lowe, 1974). Manyspecies are tolerant of highly eutrophic waters, includ-

ing G. augur, G. sphaerophorum, G. minutum, G.parvulum, and Gomphoneis olivaceum (Patrick andReimer, 1975; Krammer and Lange-Bertalot, 1986).Other species, including Gomphonema subtileEhrenberg, are indicative of oligotrophic waters(Krammer and Lange-Bertalot, 1986). Krammer andLange-Bertalot (1986) suggest G. truncatum is found in waters high in electrolytes. Local extinction ofGomphoneis species in the lower Laurentian GreatLakes was attributed to sensitivity to eutrophicationand low concentrations of silica (Kociolek andStoermer, 1988a).

C. Biotic Factors

Sphagnum bogs and other organic-rich wetlandareas commonly contain a rich diversity of Euno-tiaceae, although the biotic interactions, if any, havenot been detailed. Eunotia species are epiphytic on awide range of bryophytes and aquatic vascular plants (Krammer and Lange-Bertalot, 1991). Eunotiabilunaris var. mucophila is found in the mucilage orother algae, including the red alga Batrachospermum(Krammer and Lange-Bertalot, 1986).

Czarnecki (1995) reports several species of Cym-bella, Encyonema, and Gomphonema found within themucilage of the protozoan Ophrydium versatile.Geitler’s (1975) suggestion that C. cesatii is an obligateinhabitant of the mucilage of this protozoan has notbeen confirmed (Czarnecki, 1995). Amphora species,many of the Cymbellaceae, and the Gomphonemata-ceae are common epiphytes on a variety of aquaticalgae, bryophytes, and vascular plants.


IV. KEY AND DESCRIPTIONS OF NORTH AMERICAN GENERA

A. Key

1a. Valve outline asymmetrical about apical axis (Figs. 1A, 2A)...............................................................................................................2

1b. Valve outline symmetrical about apical axis.......................................................................................................................................9

2a. In valve view, raphe restricted to ends of valve; in girdle view, most of raphe branch on valve mantle or not evident (Fig. 1C)..........3

2b. In valve view, raphe clearly in axial area on valve face; in girdle view, only tip or short section of raphe on mantle (Fig. 3C)............6

3a. Valves asymmetrical about transapical axis (Fig. 1F)..............................................................................................................Actinella

3b. Valves symmetrical about transapical axis..........................................................................................................................................4

4a. Raphe branches indistinct, with striae uninterrupted across valve face (Fig. 1D)...................................................................Semiorbis

4b. Raphe branches visible, striae commonly interrupted near ventral margin of valve............................................................................5

5a. Dorsal and ventral margins undulate (Fig. 1G)................................................................................................................Amphicampa

5b. Ventral margin smooth; dorsal margin undulate or smooth.....................................................................................................Eunotia

6a. Valves with distal raphe ends deflected dorsally, or not as below (Fig. 2A).........................................................Cymbella (sensu lato)

6b. Valves with distal raphe ends deflected ventrally (Fig. 2E)..................................................................................................................7

7a. Stigma present, centrally positioned, with relatively small, swollen, unornamented area on ventral margin (Fig. 2J, K).........Reimeria

B. Descriptions of Genera

Catenulaceae

Amphora Ehrenberg ex Kützing 1844 (Fig. 2G–I)Valves are asymmetrical to the apical axis and sym-

metrical to transapical axis. On the dorsal margin, thevalve mantle is deeper, or higher, than that on ventralmargin. As a result, the frustule is wedge-shaped. Thewedge shape prevents complete focus in one focalplane. The raphe is in a position of moderate to strongeccentricity. Furthermore, the raphe may be straight,arched, or slightly sigmoid. Striae on the dorsal marginare usually crossed by hyaline areas, whereas striae on the ventral margin are short. Depending on theposition of the valve, the striae on the ventral marginmay difficult to see. Stigmata are lacking, and terminalnodules are indistinct. The ultrastructure of Amphorahas been considered by Archibald and Schoeman(1984), Archibald and Barlow (1983), Karayeva et al.,(1984), and Lee and Round (1987, 1988). Stoermerand Yang (1969) described several new species ofAmphora from the Laurentian Great Lakes. Mann(1984) has documented sexual reproduction inAmphora.

Although primarily a marine genus, some species(i.e., A. ovalis) of Amphora are widely distributed in fresh waters across North America. Other species(i.e., A. calumetica), are restricted in distribution to the Laurentian Great Lakes (Edlund and Stoermer,1999). The extreme asysmmetry of Amphora makes it a benthic specialist, where it may attach firmly tosubstrata, especially other algae and aquatic plants.

Cymbellaceae

Cymbella C. A. Agardh 1830 (Fig. 2A–C)Valves are slightly to stongly asymmetrical to the

apical axis, and symmetrical to the transapical axis.Species with slight asymmetry may be very close tonaviculoid symmetry. The raphe is centrally or eccentri-cally positioned. Stigmata are absent, or if present,located on the ventral side of the central area. The distal raphe ends are straight or deflected dorsally.Cells grow in benthic habitats, often surrounded bymucilage or producing mucilaginous stalks. Apical porefields may be absent, or present at both poles. Taxawith apical pore fields are likely to be found growingon stalks.

The broad sense of Cymbella embraced here(Krammer, 1982; Krammer and Lange-Bertalot, 1986;Round et al., 1990) is probably not a natural group oftaxa. As such, it contains a heterogeneous assemblageof taxa that are not referred to Encyonema orReimeria. A natural group within Cymbella containsspecies with ventrally placed stigmata, dorsally deflectedexternal distal raphe ends, and apical pore fields.Krammer’s work has led to a broad understanding of the valve (Krammer, 1982), raphe (Krammer, 1979), and girdle components of cymbelloid frustule(Krammer, 1981). Krammer (1997a, b) has begun to revise the genus and identify clusters of morphologi-cally similar species. Krammer and Lange-Bertalot(1986) offer an excellent account of common membersof the genus. Cymbella is a large genus and is oftencommon in benthic habitats across North America. As a genus, it varies greatly in size and degree of asysm-


7b. Stigma dorsal or absent; ventral margin otherwise.............................................................................................................................8

8a. Valve mantle height dissimilar between dorsal and ventral margin; dorsal mantle height higher than ventral; interruption in striationalong dorsal portion of raphe (Fig. 2H, I)..............................................................................................................................Amphora

8b. Valve mantle height similar on dorsal and ventral margins (Fig. 2E, F)..............................................................................Encyonema

9a. Valves large, robust, with multiple stigmata and single, unlobed apical pore field.......................................................Didymosphenia

9b. Valves not as above..........................................................................................................................................................................10

10a. Raphe of reduced length on one or both valves (Figs. 1E, 3K)..........................................................................................................11

10b. Raphe long, of similar length on both valves....................................................................................................................................12

11a. Septa and pseudosepta present; one valve convex, the other concave (Fig. 3.I–K)..........................................................Rhoicosphenia

11b. Septa and pseudosepta absent, valves not highly arched (Fig. 1E)............................................................................................Peronia

12a. Proximal raphe fissure with anchor-shaped ends........................................................................................................Gomphosphenia

12b. Proximal raphe fissure not anchor shaped........................................................................................................................................13

13a. Valves with longitudinal lines on either side of the axial area or with 4 or more stigmoids around central area...............Gomphoneis(one exception, see genus description)

13b. Valves without longitudinal lines and with 0, 1 or (sometimes) 2 stigmata on one side of the central area.....................Gomphonema(some exceptions, see genus description)

metry, with some species with only slight asysmmetryto the apical axis. North American species have been considered by Hufford and Collins (1972a, b),Kingston (1978), and Selva (1981). Geitler (1927,1956, 1967) and Geitler and Mack (1953) have docu-mented sexual reproduction.

Didymosphenia M. Schmidt 1899 (Fig. 2D)Valves are markedly large and robust. Symmetry

relations are asymmetry to the transapical axis andsymmetry to the apical axis (although some popula-tions are asymmetrical to the apical axis). Both apicesare capitate, and valves are wedge-shaped in girdleview. A marginal ridge of silica is present on both sidesof the valves, terminating near the headpole as spines.Septa and pseudosepta are absent. Two to several stig-mata occur on one side of the central area. The apicalpore field is not bisected by the raphe. Kociolek and Stoermer (1988c) showed that this taxon is moreclosely allied to the cymbelloid diatoms than to thegomphonemoid groups to which it had previously beenreferred. Dawson (1973a, b) studied the ultrastructureof Asian specimens; Stoermer et al., (1986) quantifiedand compared shape and shape change across severalpopulations. Meyer (1929) documented sexual repro-duction in the genus.

A single species, D. geminata, occurs in westernNorth America. It is locally abundant in some lakesand streams, at times producing high concentrations of biomass. The sheer mass of mucilaginous stalks ofD. geminata cover surfaces and may foul water intakepipes, reaching nuisance porportions.

Encyonema Kützing 1833 (Fig. 2E, F)Valves are asymmetrical to the apical axis and sym-

metrical to the transapical axis. The dorsal margin ishighly arched, whereas the ventral margin is straight ornearly so. Stigmata are lacking or, if they are present,they are located on the dorsal side of the central area.The distal raphe ends are ventrally deflected. Apicalpore fields are absent. Cells occur singly and free, produce mucilaginous sheaths, or form colonies withinmucilaginous tubes. Krammer (1982) showed that theultrastructure of the species in Encyonema consistentlydiffers from other species included in Cymbella.Kociolek et al., (1994) documented the cytoplasmicfine structure of two Encyonema species with transmis-sion electron microscopy. Taxonomy and ultrastructureof the genus are considered in Krammer (1997a, b).

Encyonema is broadly distributed across NorthAmerica, primarily in benthic habitats. In the classicalliterature many of the species in this genus are includedin Cymbella.

Reimeria Kociolek et Stoermer 1987 (Fig. 2J, K)Valves are symmetrical to the transapical axis and

asymmetrical to the apical axis. The dorsal margin isslightly arcuate, whereas the ventral margin is straightto slightly concave, and tumid at the central area. Theaxial area is narrow, and the central area is unilaterallyexpanded toward the ventral margin. A single stigma islocated just ventral to the dilated proximal raphe ends.Apical pore fields are visible at both poles on the ventral margin. The distal raphe ends are deflectedtoward the ventral margin. Kociolek and Stoermer(1987a) proposed this genus for the Cymbella sinuataspecies complex.

Reimeria is limited to a small number of speciesand is broadly distributed across North America, primarily in benthic habitats.

Eunotiaceae

Actinella Lewis 1864 (Fig. 1F)Valves are distinctly symmetrical to the apical and

transapical axes. In valve view, the raphe is not evident.The raphe is highly reduced and restricted to the ventral margin. Terminal nodules are visible. Striae are clearly visible, with small spines evident along theoutline of the valve. The cells grow singly or in smallcolonies that are joined by mucilage secreted at the narrow ends of the cells.

Almost all reports of this genus are from soft oracidic waters in eastern and southeastern North America.Actinella is differentiated from Eunotia by asymmetryabout the transapical axis. A single species, A. punctata,is extant. Morphology and distribution records of A. punctata are documented in Kociolek et al. (1997).

Amphicampa (Ehrenberg) Ralfs in Pritchard 1861(Fig. 1G)

Valves are asymmetrical to apical axis, and sym-metrical to the transapical axis. Both dorsal and ventralmargins are distinctly undulate. The raphe is short andrestricted to the distal ends.

A single species, A. eruca, is rare to uncommon incircumneutral to alkaline waters in the midwestern andwestern United States (Kociolek, 2000). The report byPatrick and Reimer (1966) of A. mirabilis in NorthAmerica cannot be confirmed.

Eunotia Ehrenberg 1837 (Fig. 1A–C)Apical axis is asymmetrical, and transapical axis is

symmetrical. Dorsal margins of the valve are convexand may be smooth or undulate. Ventral margins of thevalve are straight or concave. The raphe is restricted tothe ends and lies along the valve mantle. Distal ends of the raphe curve slightly or strongly onto the valveface at the apices. Usually, the terminal nodules are


conspicuous. In girdle view, the frustules are rectangu-lar, or boxlike. Also, in girdle view the raphe branchesare evident. Ultrastructure of the genus has been docu-mented by Alles et al., (1991), Mayama and Kobayashi(1990, 1991), and Kobayashi et al., (1981). The treat-ments by Krammer and Lange-Bertalot (1991) andLange-Bertalot and Metzeltin (1996) are very helpfulfor species-level identifications. Geitler (1951a, b,1973c) documented sexual reproduction.

Cells occur singly, free or attached by mucilaginousstalks, or in long ribbon-like colonies. The genus islarge and widespread across North America, but mostdiverse in softwater or acid-water habitats (Patrick andReimer, 1966; Krammer and Lange-Bertalot, 1991).

Peronia Brébisson et Arnott ex Kitton 1868 (Fig. 1 E)Valve outline is clavate, with a narrow central

sternum. On one valve, the raphe is short and straight,and a rimoportule is present near the apex. The othervalve lacks a raphe, or it is only rudimentary. Thisinteresting genus is similar to the Naviculaceae, in that the position of the raphe is on the valve face. Italso shares the feature of a rimoportule with theEunotiaceae (Hasle, 1973; Round et al., 1990). Themorphology of a South American species has been documented (Kociolek, 2000).

Peronia occurs rarely in North America, with scattered reports from the midwestern, southern, andeastern United States, and occurs only in acidic waters.

Semiorbis Patrick in Patrick et Reimer 1966 (Fig. 1D)Valves are highly arched and lack undulations.

They are asymmetrical about the apical axis and sym-metrical about the transapical axis. The raphe is incon-spicuous, and the terminal nodules are not evident.Cells occur singly or in short filaments. Krammer andLange-Bertalot (1991) consider Semiorbis within thegenus Eunotia. Moss et al., (1978) documented theultrastructure of S. hemicyclus with the scanning electron microscope.

Patrick and Reimer (1966) report Semiorbis fromwaters of low mineral content and humic rich waters,especially bogs, of the eastern United States. Theyincluded this genus with the araphid diatoms despiteKolbe’s (1956) report of a short raphe system.

Gomphonemataceae

Gomphoneis Cleve 1894 (Fig. 3F–H)Valves are wedge-shaped: asymmetrical to the

transapical axis, and symmetrical to the apical axis.Both septa and pseudosepta are evident. Species possesseither stigmata, longitudinal lines, and doubly punctatestriae (G. herculeana, G. eriense), or 0–4 stigmoids, nolongitudinal lines, and striae composed of indistinct

puncta (G. olivacea, G. quadripunctata). Taxonomy,ultrastructure, distribution, and phylogeny of the genushave been documented (Kociolek and Rosen, 1984;Kociolek and Stoermer, 1986, 1988a, b, 1989).

Gomphoneis is found predominantly in midwesternand western North America. Like Gomphonema, theyproduce long, mucilaginous stalks, with the cells grow-ing upward from the point of attachment of the stalk.The colonies form thick, mucilaginous masses attachedto surfaces along the shores of lakes, rivers, andstreams.

Gomphonema Ehrenberg 1832 (Fig. 3A–E)Cells are asymmetrical to the transapical axis and

asymmetrical to the apical axis, forming a wedgeshape. A single stigma is usually present on one side ofthe central area. Longitudinal lines are absent. NorthAmerican species possess striae that are usually punc-tate and not costalike. Species commonly occur individ-ually or growing at the ends of mucilaginous stalks.Some taxa form stellate colonies or occur in mucilagi-nous masses. Our understanding of the taxonomy of the genus has benefitted from contributions byReichardt and Lange-Bertalot (1991), Ueyama andKobayashi (1988), and Lange-Bertalot (1993), whohave helped to provide a better understanding of valveultrastructure. North American specimens have beentreated by Wallace and Patrick (1950), Wallace (1960),Kalinsky (1984), Czarnecki and Blinn (1979), Hohn (1959), Van Landingham (1967), Kociolek andStoermer (1987b, 1991), Kociolek et al. (1995),Kociolek and Kingston (1999), and Lowe and Kociolek(1984). Geitler (1951c, 1973b) has documented sexualreproduction in Gomphonema species.

An estimated 150 Gomphonema taxa have beenreported from the across the United States (Kociolek,unpublished). The genus is found in nearly every habi-tat type within circumneutral lakes and streams.

Rhoicospheniaceae

Gomphosphenia Lange-Bertalot 1995 (Fig. 3L)Valves are cuneate, with straight or undulate sides,

never bent or flexed. Raphe is straight, filiform withexternal terminal fissures (both proximal and distal)straight. Internally, distal raphe fissure ends in a helic-toglossa; the proximal raphe fissure has characteristicanchor-shaped endings. Stigmata are lacking. Striae areopen foramina, sometimes obscured externally to givethe appearance of “ghost” striae. Apical pore fields, septa,and pseudosepta are all wanting. Kociolek et al. (1988),Lange-Bertalot (1995), and Kociolek and Kingston(1999) document the ultrastructure of this genus.

Gomphosphenia is a small genus, relatively recentlyseparated from Gomphonema (Lange-Bertalot, 1995).


Two species, G. grovei and G. lingulataeforme, havebeen collected from widely distributed benthic habitatsof fresh waters of North America. Wallace (1960) documented variation in a taxon called Gomphonemabrasiliense, which is now considered a species ofGomphosphenia.

Rhoicosphenia Grunow 1860 (Fig. 3I–K)Valves are heterovalvate and flexed about the

transapical axis, in girdle view. The concave valve pos-sesses a raphe that extends almost the length of thevalve. The convex valve possesses short raphe branchesnear apices only, which may be difficult to discern.Asymmetrical to the transapical axis and symmetricalto apical axis in valve view. The raphe is straight, andthe proximal ends are dilated. Cells may be free orattached to surfaces by mucilage stalks.

A single species, R. abbreviata, is extant in thefreshwater flora. It is widely distributed and commonacross North America. An extinct species swarm isfound in diatomite deposits in western North America(Schmidt, 1899).

V. GUIDE TO LITERATURE FOR SPECIESIDENTIFICATION

The following is a list of key references that dealwith species found in North America. Each containscitations to older literature and resources for other con-tinents. General references: Hustedt (1930); Hustedt(1927–1930); Krammer and Lange-Bertalot (1986,1991b); Lange-Bertalot and Metzeltin (1996); Patrickand Reimer (1966, 1975).

Taxon-specific references:1. Actinella—Kociolek et al. (1997)2. Amphora—Stoermer and Yang (1971)3. Encyonema—Krammer (1997a, b)4. Cymbella—Krammer (1997a, b)5. Reimeria—Kociolek and Stoermer (1987)6. Gomphoneis—Kociolek and Rosen (1984);

Kociolek and Stoermer (1986, 1988a, b, 1989)7. Gomphonema—Wallace and Patrick (1950);

Wallace (1960); Kalinsky (1984); Czarnecki andBlinn (1979); Hohn (1959); Kociolek andStoermer (1987b, 1991); Kociolek and Lowe(1984); Kociolek and Kingston (1999)

8. Gomphosphenia—Wallace (1960); Kociolek etal. (1988); Kociolek and Kingston (1999)

9. Rhoicosphenia—Lange-Bertalot (1980).

ACKNOWLEDGMENTS

We thank R. Sheath and E. F. Stoermer for commentsand suggestions that greatly improved this chapter.

LITERATURE CITED

Alles, E., Nörpel-Schempp, M., Lange-Bertalot, H. 1991. Taxonomyand ecology of characteristic Eunotia species in headwaterswith low electric conductivity. Beihefte zur Nova Hedwigia53:171–213.

Archibald, R. E. M., Barlow, D. J. 1983. On the raphe ledge in thegenus Amphora (Bacillariophyta). Bacillaria 6:257–266.

Archibald, R. E. M., Schoeman, F. R. 1984. Amphora coffeaeformis(Agardh) Kützing: A revision of the species under light and elec-tron microscopy. South African Journal of Botany 3:83–102.

Bessey, C. E. 1899. The modern conception of the structure and clas-sification of diatoms. Transactions of the American MicroscopicalSociety 21:61–85.

Cholnoky, B. J. 1965. The relationship between algae and the chem-istry of natural waters. Council for Scientific and IndustrialResearch, Special Report 129:215–225.

Cleve, P. T. 1894. Synopsis of the naviculoid diatoms, Part 1. KongligaSvenska Vetenskaps-Akademiens Handlingar 26:1–194.

Cox, E. J. 1996. Identification of freshwater diatoms from live mate-rial. Chapman & Hall, London, 158 p.

Czarnecki, D. B. 1995. Additions and confirmations to the algal floraof Lake Itasca (MN) State Park. III. The intramucilaginousdiatom flora of the colonial peritrich ciliate, Ophrydium versa-tile (Ophrydiidae), in: Kociolek, J. P., Sullivan, M. J. Eds., Acentury of diatom research in North America. A tribute to thedistinguished careers of Charles W. Reimer and Ruth Patrick.Koeltz Scientific Books, Champaign, pp. 183–194.

Czarnecki, D. B., Blinn, D. W. 1979. Observations on southwesterndiatoms. II. Caloneis latiuscula var. reimeri, Cyclotella pseu-dostelligera f. parva and Gomphonema montezumense n. sp., newtaxa from Montezuma Well National Monument. Transactionsof the American Microsopical Society 98:110–114.

Dawson, P. A. 1972. Observations on the structure of some forms of Gomphonema parvulum Kütz. I. Morphology based on lightmicroscopy, transmission and scanning electron microscopy.British Phycological Journal 7:255–271.

Dawson, P. A. 1973a. The morphology of the siliceous com-ponents of Didymosphenia geminata. British PhycologicalJournal 8:65–78.

Dawson, P. A. 1973b. Further observations on the genus Didymosphenia.British Phycological Journal 8:197–210.

Dawson, P. A. 1973c. Observations on some species of the diatomgenus Gomphonema C. A. Agardh. British Phycological Journal8:413–423.

Dawson, P. A. 1974. Observations on diatom species transferredfrom Gomphonema C. A. Agardh to Gomphoneis Cleve. BritishPhycological Journal 9:75–82.

Edlund, M. B., Stoermer, E. F. 1999. Taxonomy and morphology ofAmphora calumetica (B.W. Thomas ex Wolle) Perag., an epi-psammic diatom from post-Pleistocene large lakes, in: Mayama,S., Idei, M., Koizumi, I., Eds., Proceedings of the XIVth interna-tional diatom symposium. Koeltz Scientific Books, Koenigstein,pp. 65–76.

Gaul, U., Geissler, U., Henderson, M., Mahoney, R., Reimer, C. W.1993. Bibliography on the fine-structure of diatom frustules(Bacillariophyceae). Proceedings of the Academy of the NaturalSciences Philadelphia 144:69–238.

Geitler, L. 1927. Die Reduktionsteilung und Kopulation von Cymbellalanceolata. Archiv für Protistenkunde 58:465–507.

Geitler, L. 1932. Der Formwechsel der pennaten Diatomeen(Kieselalgen). Archiv für Protistenkunde 78:1–226.

Geitler, L. 1951a. Zelldifferenzierung bei der Gametenbildung undAblauf der Kopulation von Eunotia. Biologisches Zentralblatt70:385–390.


Geitler, L. 1951b. Kopulation und Formwechsel von Eunotia arcus.Österreichische Botanische Zeitschrift 98:293–337.

Geitler, L. 1951c. Die Stellungen der Kopulationpartner und derAuxosporen bei Gomphonema-Arten. Abhandlungen derMathematisch-Naturwissenschaftlichen Klasse, Akademie derWissenschaften Lit. Mainz 6:217–225.

Geitler, L. 1956. Autogamie, Geschlechtbestimmung und Pyknosevon Gonenkernen bei Cymbella aspera. Planta 47:393–396.

Geitler, L. 1967. Paarung und Auxosporenbildung bei Cymbella.Österreichische Botanische Zeitschrift 114:484–489.

Geitler, L. 1973a. Auxosporenbildung und Systematik bei pennatenDiatomeen und die Cytologie von Cocconeis-Sippen. Österre-ichische Botanische Zeitschrift 122:299–321.

Geitler, L. 1973b. Zur lebensgeschichte und Morphologie pennaterDiatomeen. I. Allogamie bei Gomphonema constrictum var.capitatum (Ehr.) Cleve. Österreichische Botanische Zeitschrift122:35–49.

Geitler, L. 1973c. Bewegungs- und Teilungverhalten der Chromatophorenvon Eunotia pectinalis var. polyplastidica und anderer Eunotia-Arten bei der Zellteilung. Österreichische Botanische Zeitschrift122:185–194.

Geitler, L. 1975. Über bau Algenflora der Gallertkolonien des CiliatenOphridium versatile. Archiv für Hydrobiologie 76:24–32.

Geitler, L. 1981. Die Lage des Chromatophors in Beziehung zurSystematik von Cymbella-Arten (Bacillarophyceae). PlantSystematics and Evolution 138:153–156.

Geitler, L., Mack, B. 1953. Die Achsenlagen der Auxosporen understlingzellen bei der Diatomee Cymbella. ÖsterreichischeBotanische Zeitschrift 100:261.

Hasle, G. R. 1973. The “mucilage pore” of pennate diatoms. Beiheftezur Nova Hedwigia 45:167–186.

Hohn, M. H. 1959. Variability in three species of Gomphonemaundergoing auxospore formation. Proceedings of the Academyof Natural Sciences of Philadelphia 316:1–7.

Hufford, T. L., Collins, G. B. 1972a. Some morphological variations inthe diatom Cymbella cistula. Journal of Phycology 8:192–195.

Hufford, T. L., Collins, G. B. 1972b. The stalk of the diatom Cymbellacistula. Journal of Phycology 8:208–210.

Hustedt, F. 1926. Untersuchungen über den Bau der Diatomeen. I.Raphe und Gallertporen der Eunotioideae. Berrichte der DeutschenBotanischen Gesellschaft 44:142–150.

Hustedt, F. 1930. Bacillariophyta, in: Pascher, A. Ed., Süsswasserfloravon Mitteleuropa. Vol. 10. Fischer, Jena, 466 p.

Hustedt, F. 1952. Neue und wenig bekannte Diatomeen. III.Phylogenetische Variationen bei den rhaphidioiden Diatomeen.Berichte der Deutschen Botanischen Gesellschaft 65:133–144.

Kalinsky, R. G. 1984. Notes on Louisiana diatoms. III. Some new,rare and interesting diatoms from northwestern Louisiana, in:Proceedings of the 7th International diatom symposium. Koeltz,Koenigstein, pp. 299–306.

Karayeva, N. I., Maggerramova, N. R., Rhazeva, S. G. 1984.Morphology of the diatom frustule of the genus Amphora basedon the data of electron microscopy. Botanicheskii Zhurnal69:492–497.

Karsten, G. 1928. Bacillariophyta (Diatomeae), in: Engler, A., Prantl,K., Eds., Die naturlichen Pflanzenfamilien. Vol. 2. Englemann,Leipzig, pp. 105–303.

Kingston, J. C. 1978. Morphological variation of Cymbella delicatu-la and C. hustedtii from northern Lake Michigan. Transactionsof the American Microscopical Society 97:311–319.

Kingston, J. C., Lowe, R. L., Stoermer, E. F. 1980. The frustular morphology of Amphora thumensis (Mayer) A. Cl. from northern Lake Michigan and consideration of its systematicposition. Transactions of the American Microscopical Society99:276–283.

Kobayashi, H., Ando, K., Nagumo, T. 1981. On some endemic speciesof the genus Eunotia in Japan, in: Proceedings of the 6thInternational diatom symposium. Koeltz, Koenigstein, pp. 93–114.

Kociolek, J. P. 1998. Does each genus of diatoms have at least oneunique feature?—A reply to Round. Diatom Research 13:177–179.

Kociolek, J. P. 2000. Valve ultrastructure of some Eunotiaceae(Bacillariophyceae), with comments on the evolution of theraphe system. Proceedings of the California Academy ofSciences Occasional Proceedings, 4th Series 52:11–21.

Kociolek, J. P., Kingston, J. C. 1999. Taxonomy, ultrastructure anddistribution of gomphonemoid diatoms (Bacillariophyceae:Gomphonemataceae) from rivers of the United States. CanadianJournal of Botany 77:686–705.

Kociolek, J. P., Rosen, B. H. 1984. Observations on North AmericanGomphoneis (Bacillariophyceae). I. Valve ultrastructure of G.mammilla with comment on the taxonomic status of the genus.Journal of Phycology 20:361–368.

Kociolek, J. P., Stoermer, E. F. 1986. Observations on NorthAmerican Gomphoneis (Bacillariophyceae). II. Descriptions andultrastructure of two new species. Transactions of the AmericanMicroscopical Society 105:141–151.

Kociolek, J. P., Stoermer, E. F. 1987a. Ultrastructure of Cymbella sin-uata (Bacillariophyceae) and its allies, and their transfer toReimeria, gen. nov. Systematic Botany 12:451–459.

Kociolek, J. P., Stoermer, E. F. 1987b. Geographic range and variabil-ity of the diatom (Bacillariophyceae) Gomphonema ventrico-sum Gregory. Beihefte zur Nova Hedwigia 45:223–236.

Kociolek, J. P., Stoermer, E. F. 1988a. Taxonomy, ultrastructure, anddistribution of Gomphoneis herculeana, G. eriense and closelyrelated species. Proceedings of the Academy of Natural Sciencesof Philadelphia 140: 24–97.

Kociolek, J. P., Stoermer, E. F. 1988b. Observations on North AmericanGomphoneis (Bacillariophyceae). IV. Ultrastructure and distri-bution of Gomphoneis elegans. Transactions of the AmericanMicroscopical Society 107:386–396.

Kociolek, J. P., Stoermer, E. F. 1988c. A preliminary investigation ofthe phylogenetic relationships of the freshwater, apical porefield–bearing cymbelloid and gomphonemoid diatoms(Bacillariophyceae). Journal of Phycology 24:377–385.

Kociolek, J. P., Stoermer, E. F. 1989. Phylogenetic relationships andevolutionary history of the diatom genus Gomphoneis. Phycologia28:438–454.

Kociolek, J. P., Stoermer, E. F. 1991. Taxonomy and ultrastructure ofsome Gomphonema Ehrenberg and Gomphoneis Cleve taxafrom the upper Laurentian Great Lakes. Canadian Journal ofBotany 69: 1557–1576.

Kociolek, J. P., Stoermer, E. F. 1993a. Freshwater gomphonemoiddiatom phylogeny: Preliminary results. Hydrobiologia 269/270:31–38.

Kociolek, J. P., Stoermer, E. F., Sicko-Goad, L. 1994. Cytoplasmicfine structure of two Encyonema species. Memoirs of theCalifornia Academy of Sciences 17:235–246.

Kociolek, J. P., Stoermer, E. F., Edlund, M. A. 1995. Two new fresh-water diatom species, in: Kociolek, J. P., Sullivan, M., Eds., Acentury of progress in diatom research in North America. Atribute to the distinguished careers of C. W. Reimer and R. M.Patrick. Koeltz Scientific Books, Champaign, pp. 9–20.

Kociolek, J. P., Rhode, K., Williams, D. M. 1997. Taxonomy, ultrastructure and biogeography of the Actinella punctata(Bacillariophyta: Eunotiaceae) species complex. Beihefte zurNova Hedwigia 65:177–193

Kolbe, R. W. 1956. Zur Phylogenie des Raphe-Organs der Diatomeen:Eunotia (Amphicampa) eruca Ehr. Botanische Noten 109:91–97.

Krammer, K. 1979. Zur Morphologie der Raphe bei der GattungCymbella. Beihefte zur Nova Hedwigia 21:993–1029.


Krammer, K. 1981. Morphologic investigations of valve and girdle ofthe diatom genus Cymbella Agardh. Bacillaria 4:125–146.

Krammer, K. 1982. Valve morphology in the genus Cymbella, in:Helmcke, J. G., Krieger, W., Krammer, K. Eds., Micromorphologyof Diatom Valves 11: 1–300.

Krammer, K. 1997a. Die cymbelloiden Diatomeen. Eine Monographieder weltweit bekannten Taxa. Teil 1. Allgemeines und EncyonemaPart. Bibliotheca Diatomologica 36:1–382.

Krammer, K. 1997b. Die cymbelloiden Diatomeen. Eine Monographieder weltweit bekannten Taxa. Teil 2. Encyonema Part., Encyonopsisund Cymbellopsis. Bibliotheca Diatomologica 37:1–469.

Krammer, K., Lange-Bertalot, H. 1986. Bacillariophyceae. Part 1.Naviculaceae, in: Ettl, H., Gerloff, J., Heynig, H., Mollenhauer,D., Eds., Süsswasserflora von Mitteleuropa, Vol. 2. Fischer,Stuttgart, 876 p.

Krammer, K., Lange-Bertalot, H. 1991. Vol. 2. Bacillariophyceae.Part 3. Centrales, Fragilariaceae, Eunotiaceae, in: Ettl, H.,Gerloff, J., Heynig, H., Mollenhauer, D., Eds. Süsswasserfloravon Mitteleuropa, Vol. 2. Fischer, Stuttgart, 576 p.

Lange-Bertalot, H. 1980. Ein Beitrag zur Revision der GattungenRhoicosphenia Grun., Gomphonema C. Ag., Gomphoneis Cl.Botanische Noten 133:585–594.

Lange-Bertalot, H. 1993. 85 Neue Taxa und über 100 weitere neudefinierte Taxa ergänzend zur Süsswasserflora von MitteleuropaVo. 2/1–4. Bibliotheca Diatomologica 27:1–454.

Lange-Bertalot, H. 1995. Gomphosphenia paradoxa nov. sp. et nov.gen. und Vorschlag zur Lösung taxonomischer Probleme infolgeeines veränderten Gattungskonzepts von Gomphonema(Bacillariophyceae). Beihefte zur Nova Hedwigia 60:241–252.

Lange-Bertalot, H, Metzeltin, D. 1996. Ecology–diversity–taxonomy.Indicators of oligotrophy. Iconographia Diatomologica, Vol. 2.Koeltz Scientific Books, Koenigstein, 390 p.

Lee, K., Round, F. E. 1987. Studies on freshwater Amphora species.I. Amphora ovalis. Diatom Research 2:193–203.

Lee, K., Round, F. E. 1988. Studies on freshwater Amphora species.II. Amphora copulata (Kütz.) Schoeman and Archibald. DiatomResearch 3:217–225.

Lowe, R. L. 1974. Environmental Requirements and Pollution Toleranceof Freshwater Diatoms. EPA-670/4-74-005. EnvironmentalProtection Agency, Cinncinnati, 334 p.

Lowe, R. L., Kociolek, J. P. 1984. New and rare diatoms from GreatSmoky Mountains National Park. Beihefte zur Nova Hedwigia39:465–476.

Mann, D. G. 1982a. Structure, life history and systematics ofRhoicosphenia. I. The vegetative cell of Rhoicosphenia curvata.Journal of Phycology 18:162–176.

Mann, D. G. 1982b. Structure, life history and systematics ofRhoicosphenia. II. Auxospore formation and perizonium structure of Rhoicosphenia curvata. Journal of Phycology18:264–274.

Mann, D. G. 1984. Observation on copulation in Navicula pupulaand Amphora ovalis in relation to the nature of diatom species.Annals of Botany (London) 54:429–438.

Mayama, S., Kobayashi, H. 1990. Studies on Eunotia species in theclassical “Degernäs Material” housed in the Swedish Museumof Natural History. Diatom Research 5:351–366.

Mayama, S., Kobayashi, H. 1991. Observations on Eunotia arcusEhr., type species of the genus Eunotia. Japanese Journal ofPhycology 39:131–141.

Metzeltin, D., Lange-Bertalot, H. 1995. Kritische Wertung der Taxain Didymosphenia (Bacillariophyceae). Beihefte zur NovaHedwigia 60:381–406.

Meyer, K. 1929. Über die Auxosporenbildung von Gomphonemageminatum. Archiv für Protistenkunde 66:421–435.

Moss, M. O., Gibbs, G., Gray, V., Ross, R. 1978. The presence of

a raphe on Semiorbis hemicyclus (Ehr.) R. Patr. Bacillaria1:137–150.

Patrick, R., Hohn, M., Wallace, J. H. 1954. A new method for deter-mining the pattern of the diatom flora. Notulae Naturae of theAcademy of Natural Sciences of Philadelphia 259:1–12.

Patrick, R. M., Reimer, C. W. 1966. The diatoms of the United States.Monograph 13. Academy of Natural Sciences of Philadelphia,688 p.

Patrick, R. M., Reimer, C. W. 1975. The diatoms of the United States.Vol. 2, Part 1. Monograph 13. Academy of Natural Sciences ofPhiladelphia, 213 p.

Reichardt, E. 1999. Zur Revision der Gattung Gomphonema. Die Artenum G. affine/insigne, G. angustatum/micropus, G. acuminatumsowie gomphonemoide Diatomeen aus dem Oberoligozän inBöhmen. Iconographia Diatomologica 8:1–203.

Reichardt, E., Lange-Bertalot, H. 1991. Taxonomische Revision desArtenkomplexes um Gomphonema angustatum–G. dichoto-mum–G. intricatum–G. vibrio und ähnlicher Taxa(Bacillariophyceae). Beihefte zur Nova Hedwigia 53:519–544.

Round, F. E., Crawford, R.M., Mann, D. G. 1990. The diatoms.Biology and morphology of the genera. Cambridge Univ. Press,Cambridge, UK, 747 p.

Sala, S. E., Guerrero, J. M., Ferrario, M. E. 1993. Redefinition ofReimeria sinuata (Gregory) Kociolek and Stoermer and recogni-tion of Reimeria uniseriata nov. sp. Diatom Research 8:439–446.

Schmidt, M. 1899. Tafel 215, in: A. Schmidt et al., Eds., Atlas derDiatomaceenkunde. Reisland, Leipzig.

Selva, J. 1981. Tertiary freshwater diatoms from the Ogallala ofwestern Kansas. Proceedings of the Iowa Academy of Sciences88:85–90.

Skvortzow, B.W., Meyer, K. 1928. A contribution to the diatoms ofBaikal Lake. Proceedings of the Sungaree River BiologicalStation 1:1–55.

Smol, J. P. 1990. Paleolimnology: recent advances and future chal-lenges. Memorie Istituto Italiano di Idrobiologia 47:253–276.

Stoermer, E. F., Yang, J. J. 1971. Contributions to the diatom flora ofthe Laurentian Great Lakes. I. New and little-known species ofAmphora (Bacillariophyta, Pennatibacillariophyceae). Phycologia10:397–409.

Stoermer, E. F., Qi, Y., Ladewski, T. B. 1986. A quantitative investi-gation of shape variation in Didymosphenia (Lyngbye) M.Schmidt (Bacillariophyta). Phycologia 25: 494–502.

Ueyama, S., Kobayashi, H. 1988. Two Gomphonema species withstrongly capitate apices: G. sphaerophorum and G. pseu-dosphaerophorum sp. nov., in: Proceedings of the 9th interna-tional diatom symposium Koeltz, Koenigstein, pp. 449–458.

Van Landingham, S. L. 1967. A new species of Gomphonema fromMammoth Cave, Kentucky. International Journal of Speleology2:405–406.

Van Landingham, S. L. 1969. Catalogue of the fossil and Recent gen-era and species of diatoms and their synonyms. Part III.Coscinophaena through Fibula. Cramer, Weinheim, Germany,pp. 1087–1756.

Van Landingham, S. L. 1978. Catalogue of the fossil and Recent generaand species of diatoms and their synonyms. Part IV. Fragilariathrough Naunema. Cramer, Weinheim, Germany, pp. 1757–2385.

Vyverman, W., Sabbe, K., Mann, D. G., Kilroy, C., Vyverman, R.,Vanhutte, K., Hodgson, D. 1998. Eunophora gen. nov.(Bacillariophyta) from Tasmania and New Zealand: Descriptionand comparison with Eunotia and amphoroid diatoms. EuropeanJournal of Phycology 33:95–111.

Wallace, J. H. 1960. New and variable diatoms. Notulae Nature331:1–8.

Wallace, J. H., Patrick, R. M. 1950. A consideration of Gomphonemaparvulum Kütz. Butler University Botanical Studies 9:227–234.


18 – EUNOTIOID AND ASYMMETRICAL NAVICULOID DIATOMS

Documents

Transcript of 18 – EUNOTIOID AND ASYMMETRICAL NAVICULOID DIATOMS