Ecological Distribution of Cellular Slime Molds in Forest Soils of Germany James C

Bot Relv 105:199-219 0253-1453/95/020199-21 $1.50+0.20/0 @ 1995 Birkhiiuser Verlag, Basel

Ecological distribution of cellular slime molds in forest soils of Germany James C. Cavender 1, Jeannine Cavender-Bares2 and Hans R. Hohl3 1 Department of Environmental and Plant Biology, Ohio University, Athens, Ohio 457011-2979 USA 2 Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massa- chusetts 02138 USA 3 I!lstitute of Plant Biology, University of Zurich, Zollikerstr. 107, CH-8008 Zurich, Switzerland

Manuscript acceptedSeptember 18, 1995

Abstract

Cavender J. C., Cavender-Bares J., and Hohl H. R. 1995. Ecological distribution of cellular slime molds in forest soils of Germany. Bot. Helv. 105: 199-219. Surface soils were collected from deciduous, coniferous and mixed coniferous-deciduous forest of Germany during the latter half of July 1993 and were plated out for cellular slime molds at Ohio University during the first half of August, 1993. Twenty-four sites were sampled from different geographical regions in southern, central and western Germany. Germany has a fairly diverse cellular slime mold flora/fauna similar to that of the cool temperate zone of Japan and to the North American bi-state region of Ohio and West Virginia. Eighteen morphological species were isolated which match those described in the literature. Three entities were isolated only once, hence are considered to be rare: Acytostelium leptosomum, Dictyostelium capitatum, and a new species, Dictyos- telium germanicum. Four species originally described from Japan were isolated for the first time from Europe: Dictyostelium microsporum, D. capitatum, D. implicatum and Polysphondylium candidum. The most commonly isolated were Dictyostelium mucoroides, S-type and Polysphondylium violaceum. Cellular slime mold populations of deciduous and coni(erous forests have distinct differences. Numbers of clones per gram and species richness were higher in soils of deciduous forests than in coniferous forests. Key words: Cellular slime mold, dictyostelid, ecological distribution, forest soil.

Introduction

Cellular slime molds were introduced to the world by Oskar Brefeld, a German mycologist, with his report of the discovery of Dictyostelium mucoroides in 1869. He also described Polysphondylium violaceum (1884), although he did not find these cellular slime molds in.(orest soils. Oehler (1922), working in Wiirzburg, reported that D. mucoroides could be isolated from forest soil. We have found these two species to be the most common in Central Europe. Hagiwara (1984) has assembled evidence to show that

199 200 JamesC. Cavenderet al.

Brefeld's descriptionof D. mucoroidesmatches most closely another cosmopolitanspe- cies which Raper (1984) designatedas D. sphaerocephalum(Oud.) Saccoet March. Hagiwara createdthe nameD. brefeldianumfor the taxon we are naming D. mucoroides, S-type.Because there is no holotype designatedand preservedfrom Brefeld's description, we are, for the time being, using Raper's taxonomy. Cavender(1969) was the first to make an ecologically-baseddistributional study of Europe. However,only two siteswere sampled in Central Europe,one in WestGermany and one in Switzerland.Traub (1972)later did a comprehensivesurvey of cellular slime molds in Switzerland which was augmented by further collections of Cavenderand published in 1981 (Traub, Hohl and Cavender1981 a, 1981b). Three new specieswere described:Dictyostelium fasciculatum, D. polycarpum,and Polysphondyliumfilamento- sum. Traub also designatedtwo types of D. mucoroidesas Sand L types. This differen- tiation of D. mucoroideshas beencontinued in this study. They may representdistinct species.Leitner (1987)made someinteresting observations of three cellular slime molds with respectto forest soil pH. He found Dictyosteliummucoroides and D. fasciculatum more prevalent in deciduousforest with neutral or slightly alkaline soils while D. minu- turn was more common in deciduousforest soils which were acidic (ca. pH 5.0). In this study, Dictyostelium implicatum Hagiwara, D. microsporum Hagiwara, D. capitatum Hagiwara, D. germanicumnsp., D. septentrionalisCavender, and Poly- sphondyliumcandidum Hagiwara are reported for the first time from Europe. Dictyoste- lium germanicumwas isolated from a mature beechforest within a Tertiary volcaniccone in the Eifel region of the Rhineland Palatinate. It is unique in having small solitary sorocarpsbearing oblong sporeswith numerousunconsolidated polar granules.

Study Area

Germany,with an areaof357,000 square kIn, hasa great diversity of topographyand soils due to a rather complexorogeny. Among the microenvironmentspresent are those influencedby glacial till, including sandand bog environments,limestone, sandstone and basaltic bedrock, as well as considerableloess deposits in certain areas. Most of the country is broken into mountains and valleys by a network of rivers of considerable water volume indicative of an abundant rainfall distributed throughout the year (Ellen- berg 1988). Air temperature in summer seldomexceeds 30°C and in winter -20°C. "Such a climate encouragesthe universal growth of trees" (Ellenberg 1988). Despite considerableagricultural activity, Germany still has over one third of its land in forest. The climate favors beech(Fagus sylvatica) and oak (Quercusrobur) but there are also somedeciduous woodlands with an assortmentof dominants suchas maple (Acer)and linden (Tilia). Conifers,spruce (Picea abies) and Scotspine (Pinussylvestris) are naturally dominant in the northeast and at higher elevations although much of the deciduous forest of central and westernGermany has beenreplaced by conifer plantations.

Methods

Fifty gram soil sampleswere collected in Whirl Pac plastic bags during late July and early August 19~ and processedfor Dictyostelidaein a way similar to that reported by Cavenderand Raper(1965). However,all cultureswere shakenby hand rather than by machine.All of the soils were processedduring late August 1993at Ohio University upon return from Germany. Botanica Helvetica 105/2, 1995 201

The method of analyzingdictyostelid populations in soil is basedon the appearanceof clones of cellular slime molds on a dilute hay-infusion agar surface which has beeninoculated with an appropriate soil dilution and a pre-grownbacterial food supply. Coloniesof the developingorgan- isms are identified and counted in the isolation plates. Unidentifiable colonies are removed to two-memberedcultures with Escherichiacoli Blr for further study.The acrasianpopulations in each forestare expressedin terms of frequency,relative density,and density(Tables 2-4). Densityis the total number of clonesper gram of soil while frequencyis the number of times a speciesoccurs at a particular site expressedas a percentage,and relative densityis the relative number of colonies of eachspecies at a site expressedas a percentage.Isolates of eachspecies were cultivated on non-nu- trient agar with 24 hour pre-grownE. coli and preservedby lyophilization in the KennethB. Raper cellular slime mold collectionhoused at Ohio University. Soil pH was measuredin the lab using a RadiometerION83 ION METER. Photomicrographswere takenusing an Olympusphase contrast microscope. Forests in foothills, mountainousareas and lowlands were sampled in central, western,and southernGermany (Fig. 1). The lowlands of northernand easternGermany, however, were exclud- ed due to time constrai~tsexcept for one site (LH). Characteristicsof eachsite are listed in Table 1. Theseinclude location, date of collection,geographical region, forest type, dominant trees,geolog- ical features,elevation, humus type and soil pH.

Results

The results of the distributional study are presented in Tables 2-4. Dictyostelids recovered from soils of coniferous or mixed coniferous deciduous forest are presented in Table 2, dictyostelids recovered from neutral or alkaline soils in deciduous forests are presented in Table 3, and dictyostelids recovered from acid soils in deciduous forests are presented in Table 4. Comparisons of the cellular slime mold populations in these three environments within Germany can, therefore, be made more easily. Eighteen of the nineteen species isolated are illustrated with photomicrographs in Figs. 2-55. Spores, aggregation pattern and sorocarps are reproduced. Descriptions of these species except for Traub's D. mucoroides L-type may be found in either Raper's (1984) or Hagiwara's (1989) monographs, therefore our comments are limited to salient features. A description and Latin diagnosis of D. germanicum is presented here. Dictyostelium germanicum Cavender, Cavender-Bares, et Hohl sp. novo (Figs. 50, 51, 52) Sorocarpia plerumque solitaria, erecta, magnitudine regularissima, normaliter 0.5-1.5 mm longa, ecolorata; sorophoria cellulis uniserialiter dispositis, diametro basali circa 23-26 J.Ufiad 4-6 J.Ufiangustata ad apicem; sori globosi 60-120 J.Ufi;aggregationes tumuliformes 160-260 !lm, interdum margine brevibus radiis striatae, sporae ellipticae obtusae, plerumque 3-4 x 6-8 !lm granulis polaribus non consolidatis, Stirps typica: ME-1. Sorocarps usually solitary, erect, very uniform in size, usually 0.5-1.5 mm long, unpigmented, sorophores with a single tier of cells taper from about 23 -26 !lm at the base to 4-6 !lm at the tip; sori spherical mostly 60-120 !lm in diameter; aggregations mound-like 160-260 !lm, sometimes with short streams, spores elliptical with blunt ends, mostly 3-4 x 6-8!lm with numerous unconsolidated polar granules. Type strain ME-1 deposited in Kenneth B. Raper dictyostelid collection at Ohio University. Habitat: leaf mold of a mature beech forest located within a volcanic cone of the Eifel region in -the Rhineland Palatinate. 1. D. mucoroides, S-type, RO-1b, Figs. 2-4. Unpigmented, single large sorocarps with basal discs of supporting cells, radiate aggregates, spores without polar granules. 202 James C. Cavender et at.

Table 1. Collection sites.

Niedersachsen(Lower Saxony) Geologicfeatures: Mountain, basaltcliffs LH Site: Liineburger Heide Elevation:200-500 m Date: 7.29.93 Humustype: mull Region: LiineburgerHeide Soil pH: 4.7RS (Luneberg Heath) Site: RothaargebirgejSiegen Foresttype: Mixed coniferous-deciduous Date: 7.26.93 Dominanttrees: Beech(Fagus), Region: Rothaargebirge Oak (Quercus),Birch (Betula), Foresttype: Mixed coniferous-deciduous Pine (Pinus),Spruce (Picea) Dominanttrees: Beech,Oak, Spruce Geologicfeatures: glacial moraine Geologicfeatures: mountainous Elevation: 50-100 m Elevation: 600 m Humustype: mor Humustype: mor Soil pH: 3.6 Soil pH: 4.8 TH Site: TorfllausjHarz Date: 7.30.94 Region: Harz Rheinland-Pfalz(Rhineland Palatinate) Foresttype: Coniferous KM Site: Kobern/Mosel Dominanttrees: Spruce Date: 7.23.93 Geologicfeatures: mountainous Region: Eifel, Mosel Valley Elevation: 800m Foresttype: Deciduous Humustype: mor Dominanttrees: Hornbeam (Ostrya) Soil pH: 3.8 Geologicfeatures: elevated terrain along Mosel river Elevation: 150-250 m Nordrhein-Westfalen Humustype: mull (North Rhine Westphalia) Soil pH: 4.2 KV Site: Kottenforstville in Bruhl ME Site: Miiuseberg/Eifel Date: 7.23.93 Date: 7.21.93 Region: Rhine Valley, Region: Eifel northern RheinischesSchilefergebirge Foresttype: Deciduous Foresttype: Deciduous Dominanttrees: Beech,Hawthorn Dominanttrees: Basswood(Tilia), (Crataegus) Maple (Acer), Birch Geologicfeatures: north facing slope of Geologicfeatures: glacial lake basin lake basin Elevation: 150m Elevation: 450-550 m Humus type: mull Humustype: mull Soil pH: 7.0 Soil pH: 5.7 EW Site: Elmpter Wald/Dutch Border Date: 7.23.93 Region:Niederlandisches Tiefland Hessen(Hesse) (Dutch lowland) RG Site: Rheingau Foresttype: Mixed coniferous-deciduous Date: 7.20.93 Dominanttrees: Pine, Oak, Birch Region: Rheingaugebirge,Taunus Geologicfeatures: glacial moraine Foresttype: Deciduous Elevation: < 100m Dominanttrees: Chestnut (Castanea), Humus type: mor Oak, Cherry (Prunus),Hawthorn, Soil pH: 4.8 Basswood DR Site: Drachenfels/Rhein Geologicfeatures: elevated terrain along Date: 7.25.93 Rhine river Region.:.Siebengebirge Elevation:450-500 m Foresttype: Deciduous Humustype: mull Dominanttrees: Beech Soil pH: 4.5 Helvetica 105/2, 1995 203

Table Collection sites(continued).

TN Site: Taunus summit Dominanttrees: Beech Date: 7.20.93 Geologicfeatures: lake shore Region:Taunus Elevation:400 m Foresttype: Deciduous Humustype: moder Dominanttrees: Alder (Alnus)Birch, Soil pH: 4.4KS Beech,Larch (Larix), Oak Site: Kaiserstuhl Geologicfeatures: mountainous gorge Elevation: 500m Date: 8.9.93 Humustype: mull Region: Schwarzwald(Black Forest) Soil pH: 4.5 Foresttype: Coniferous Dominanttrees: Hazel Nut (Corylus), SO Site: StarkenbergjOdenwald Maple, Beech,Ash, Locust (Robinia), Date: 8.9.93 Poplar (Populus) Region:Odenwald Geologicfeatures: loess deposits Foresttype: Deciduous Elevation: <450 m Dominanttrees: Walnut (Juglans),Maple, Humustype: mull Beech,Sycamore (Platanus), Oak, Soil pH: 7.6 Chestnut, Basswood,Ash (Fraxinus) Geologicfeatures: limestone parent material Bayern (Bavaria) Elevation: 500m WO Site: Wonsee/FriinkischeSchweiz Humustype: mull Date: 8.2.93 Soil pH: 7.0 Region: Friinkische Schweiz Foresttype: Mixed coniferous-deciduous Baden-Wurttemberg Dominanttrees: Oak, Alder, Beech, RO Site: Rothenburg ob der Tauber Ironwood (Carpinus),Basswood, Date: 8.4.93 Hornbeam, Spruce,Birch Region: Schwiibisch-Friinkisches Geologicfeatures: limestone outcrops Stufenland Elevation:400-450 m Foresttype: Deciduous Humus type: mull Dominanttrees: Walnut, Maple, Birch, Soil pH: 7.0 Basswood HS Site: Haag/Steigerwald Geologicfeatures: limestone parent Date: 8.3.93 material, steepslope Elevation:450-500 m Region: Steigerwald Foresttype: Mixed coniferous-deciduous Humustype: mull Dominanttrees: Beech,Spruce, Oak, Soil pH: 7.7 Pine, Birch EB Site: EriskirchjBodenseej Geologicfeatures: sandstone ravine Reid Naturschutzgebiet Elevation: 450m Date: 8.7.93 Humustype: moder Region: Lake Constance, Soil pH: 4.6 belowSchwiibische Alb DF Site: Danube, west of Ingolstadt Foresttype: Deciduous Date: 8.5.93 Dominanttrees: Oak, Birch Region:Danube flood plane, Geologicfeatures: lake shore Friinkische Alb Elevation:400 m Foresttype: Deciduous Humustype: mull Soil pH: 6.9 Dominanttrees: Ash Geologicfeatures: Danube river EK Site: EriskirchjBodensee flood plain Date: 8,7.93 Elevation: 380m Region: Lake Constance, Humustype: mull belowSchwiibische Alb Soil pH: 7.3

Botanica 204 JamesC. Cavenderet al.

Table1. Collection sites(continued).

SV Site: Spitzing-SeejVoralpen Ff Site: FriedrichrodafThiiringerWald Date: 8.6.93 Date: 7.31.93 Region: Bayerische Alpen (Bavarian Alps) Region: Thiiringer Wald Forest type: Coniferous Foresttype: Mixed coniferous-deciduous Dominanttrees: Spruce,Fir (Abies) Dominanttrees: Spruce,Birch, Beech, Geologicfeatures: steepmountain slope, Maple, Hazel Nut, Alder limestoneparent material Geologicfeatures: bordering an upland Elevation: 1200-1500m swamp Humustype: mull Elevation: 600-800 m Soil pH: 7.3 Humustype: moder Comments:forest die-backevident Soil pH: 3.5

Freistaat Sachsen(Free State of Saxony) Thiiringen (Thuringia) HE Site: HomersdorfjErzgebirge DH Site: Barbarossahohle Date: 8.2.93 Date: 7.30.93 Region: SachsischesBergland just above Region: Thiiringer Becken,Hainleite the Erzgebirge Foresttype: Deciduous Foresttype: Coniferous Dominanttrees: Maple, Oak Dominanttrees: Spruce Geologicfeatures: limestone, Geologicfeatures: mountainous Karst topography Elevation: 550m Elevation: 200-250 m Humustype: mOT Humus type: mull Soil pH: 3.5 Soil pH: 7.3 FB Site: FichtelbergjCzechborder SH Site: Sondershausen Date: 8.2.93 Date: 7.30.93 Region: Erzgebirge Region: Thiiringer Becken,Hainleite Foresttype: Coniferous Foresttype: Deciduous Dominanttrees: Spruce Dominanttrees: Oak Geologicfeatures: mountainous Geologicfeatures: Elevation: 1200m Elevation:200-250 m Humustype: mOT Humus type: mull Soil pH: 3.7 Soil pH: 4.7 Comments:serious forest die-back

2. D. mucoroides,L-type, KS-2, Figs. 5-7. Unpigmented, single, large phototrophic sorocarps; sorophores without basal discs, radiate aggregations develop distinctive lumpy centers,sorogens elongated, slightly larger spores than S-type, spores without polar granules. 3. D. implicatum,HS-4, Figs. 8-10. Radiate aggregation,robust solitary sorocarpswith basaldiscs become tangled when grown in diffuse light; sporestend to germinateto form secondarysorocarps, spores without polar granules and larger than those of D. mu- coroidesS-type. 4. D. aux.eo-stipesvar. aureo-stipes,RO-4, Figs. 11-13. Irregularly branched flexuous sorocarps with yellow sorophoreswhen grown in the dark; aggregatesbreak up into smallercenters; spores with conspicuousconsolidated polar granules. Helvetica 105/2, 1995 205

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--."."~ Fig. 1. Map of Germany showing the locations of the twenty-four collection sites. LH -Luneburger Heide, TH -TorfhausjHarz, KV -Kottenforstville in Bruhl, EW -Elmpter WaldjNetherlands border, DR -DrachenfelsjRhein, RS -RothaargebirgejSiegen, KM -KobernjMosel, ME - MiiusebergjEifel, RG -Rheingau, TN -Taunus summit, SO -StarkenbergjOdenwald, RO - Rothenburg ob del Tauber, EB -EriskirchjBodenseejReid Naturschutzgebiet, EK -Eriskirchj Bodensee, KS -Kaiserstuhl, WO -WonseesjFriinkische Schweiz, HS -HaagjSteigerwald, DF - Danube f1~dplain, Ingolstadt, SV -Spitzing-SeejVoralpen, BH -Barbarossahohle, SH -Sonder- hausen, FT -FriedrichrodajThuringer Wald, HE -HomersdorfjErzgebirge, FB -Fichtelbergj Czech border. Botanica Helvetica 105/2,1995 209 210 JamesC. Cavenderet al.

Figs. 11-19. Photomicrographsof Dictyosteliumaurea-stipes var. aurea-stipes,D. aurea-stipesvar. helvetiumand Polysphondyliumviolaceum. 11-13. D. aurea-stipesvar. aurea-stipes.11. Spores, x 750. 12...Aggregation,x 40. 13. Sorocarps,x 40.14-16. D. aurea-stipesvar. helvetium.14. Spores, x 750. 15. Aggregation, x 40. 16. Sorocarps, x 40. 17-19. P. violaceum.17. Spores, x 750. 18. Aggregation, x 40. 19. Sorocarps, x 40. Botanica Helvetica 105/2, 1995 211

Figs. 20-28. Photomicrographsof Polysphondyliumpallidum, P. filamentosumand P. candidum. 20-22. P...pallidum.20. Spores, x 750. 21. Aggregation, x 40. 22. Sorocarps, x 40. 23-25. P.filamentosum.23. Spores, x 750. 24. Aggregation, x 40. 25. Sorocarps, x 40. 26-28. P. candidum.26. Spores, x 750. 27. Aggregation, x 40. 28. Sorocarps, x 40. 212 JamesC. Cavenderet al.

Figs. 29-37. Photomicrographsof Dictyosteliumseptentrionalis, D. sphaerocephalum,and D.fasciculatum.29-.J1. D. septentrionalis.29. Spores, x 750.30. Aggregation, x 40.31. Sorocarps, x 40. 32-34. D. sphaerocephalum.32. Spores, x 750.33. Aggregation, x 40.34 Sorocarps, x 40.35-37. D. fasciculatum.35. Spores, x 750. 36. Aggregation, x 40. 37. Sorocarps, x 40. Botanica Helvetica 105/2, 1995 213

Figs. 38-46. Photomicrographsof D. polycarpum,D. microsporumand Acytosteliumleptosomum. 38-40. D. }I(Ilycarpum.38. Spores, x 750. 39. Aggregation, x 40. 40. Sorocarps, x 40. 41-43. D. microsporum.41. Spores, x 750.42. Aggregation, x 40. 43. Sorocarps, x 40. 44-46. Acytosteli- um leptosomum.44. Spores, x 750. 45. Aggregation, x 40. 46. Sorocarps, x 40. 214 JamesC. Cavenderet at.

Figs. 47-55. Photomicrographs of Dictyostelium minutum, D. germanicum,and D. capitatum. 47-49. 1). minutum. 47. Spores, x 750. 48. Aggregation, x 40. 49. Sorocarps, x 40. 50-52. D. germanicum.50. Spores,x 750.51. Aggregation, x 40.52. Sorocarps,x 40.53-55. D. capitatum. 53. Spores, x 750. 54. Aggregation, x 40. 55. Sorocarps, x 40. Botanica Helvetica 105/2, 1995 215

5. D. aureo-stipesvar. helvetium,FT-l, Figs. 14-16. Irregularly branched sorocarps, robust and erectsorocarps with yellow sorophoreswhen grown in the dark; aggregates break up into smaller units, sporeswith conspicuousconsolidated polar granules. 6. P. violaceum,FT-5, Figs. 17-19. Purple to violaceous pigmentation of sorocarps, whorled branches;aggregates break up, sporeswith consolidated polar granules. 7. P. pal/idum, LH-4, Figs.20-22. Unpigmented sorocarps, numerous whorls of branches,radiate aggregation,spores with unconsolidatedpolar granules. 8. P.filamentosum,RS-5, Figs. 23-25. Distinguished by the elongatedterminus of the main axis as well as the axesof the whorled branchesof the sorocarps,radiate aggregation, unconsolidatedpolar granules. 9. P. candidum,ME-2, Figs. 26-28. Unpigmented sorocarps,terminal segmentmay be elongated,radiate aggregation,more robust than P. pal/idum with fewer whorls, large sporeswith unconsolidatedpolar granules. 10. D. septentrionalis.FB-l, Figs. 29-31. Very robust thick sorocarps often with ex- pandedbases, radiate aggregations,will not grow above20 °C, large sporeswithout polar granules. 11. D. sphaerocephalum,KS-5, Figs. 32-34. Small but stout sorocarps,characterized by thick sorophore tips with slime collars and well developed supporters of prostate sorophores,spores without polar granules. 12. D.jasciculatum, RO-la, Figs. 35-37. Severalsorocarps per aggregate,aggregates break up, conspicuousconsolidated polar granules. 13. D. polycarpum,KS-4, Figs. 38-40. Small coremiform sorocarps,mound-like aggregates or short streams, relatively long spores with conspicuousunconsolidated polar granules. 14. D. microsporum,HE-4, Figs. 41-43. Severaldelicate sinuous sorocarps develop from an aggregate,aggregates mound-like developing a lobed stream network when older, sporesof two sizeswith conspicuousconsolidated polar granules. 15. Acytostelium leptosomum,DR-4, Figs. 44-46. Minute size;mound-like aggregates, sometimeswith streams;acellular, very delicate sorocarps;spherical spores. 16. Dictyosteliumminutum, HS-2, Figs.47-49. Smallsize; mound-like aggregationwith reversestreaming when older, solitary or more commonly severalsorocarps per aggregate, sporeswith or without inconspicuouspolar granules. 17. D. germanicum,ME-l, Figs. 50-52. Small size;mound-like aggregates;single soro- carp per aggregate;oblong sporeswith numerousunconsolidated polar granules. 18. D. capitatum,TH-2, Figs. 53-55. Delicate; mound-like aggregatesor short, coarse streams; severalsorocarps per aggregate;sorophores with capitate tips; spores with inconspicuouspolar granules. 19. D. giganteum,FT -2, not illustrated. Very similar to D. mucoroidesS-type with much longer erector- creepingsorophores. 216 JamesC. Cavenderet al.

Key to the dictyostelidsof Germany

Sorophoresacellular (Acytostelium) sporesspherical, sorocarps very delicate Acytosteliumleptosomum (Figs. 44-46) 1. Sorophorescellular, sporeselliptical. 2 2. Sorocarpsunbranched or branchedbut never with whorled branches(Dictyostelium ) 2. Sorocarpstypically with whorls of branches(Polysphondylium) . 3 3. Sorocarpspigmented, sorophores and son violet to purple. .. Polysphondyliumviolaceum (Figs. 17-19) 3. Sorocarpsunpigmented4. 4 Whorls numerous. .. Polysphondyliumpa//idum (Figs. 20-22) 5.4.Whorlsfew Lateral branch tips elongated, tips of main axis also elongated 5

Polysphondyliumfilamentosum (Figs. 23-25) 5. Lateral branchesnot elongated,main axis tips may be elongated Po/ysphondy/iumcandidum (Figs. 26-28) 6. Sorocarpsunpigmented and without whorled branches. 8 6. Sorocarpspigmented, sorophores yellow in reducedlight or darkness. 7 7. Sorophoreserect, branched,spores with conspicuouspolar granules, conifer or mixed coniferousdeciduous forests. .Dictyoste/ium aureo-stipesvar. he/vetium (Figs. 14-16) 7. Sorophoresprone or flexuous,branched; spores with conspicuouspolar granules; deciduousforest. Dictyoste/iumaureo-stipes var. aureo-stipes (Figs. 11-13) 8. Sorocarpssmall, mostly < 2 mm high, sorophorescomposed of a single tier of cells.. 15 8. Sorocarpsmedium, large or very large >2 mm to 1.5 cm, sorophorescomposed of more than one cell incross section 9 9. Aggregationlarge, radial, do not break up 10 9. Aggregationslarge, initially radial but break up into numerous smaller aggregations, sorocarpsclustered, spores with conspicuouspolar granules,abundant in deciduousforests with neutral or alkaline humus. Dictyoste/iumfascicu/atum (Figs. 35-37) Sorocarps very large, reaching 5-15 mm in height. 11 10. Sorocarps large but mostly <5 mm unless exposed to one-sided illumination. 12 11. Sorocarps erect, robust 1.0-1.5 cm high, very large sori (up to 500 1Un),arising from expanded, conical bases; will not fruit above 20 °c Dictyostelium septentrionalis (Figs. 29-31) 11. Sorocarps erect, 5-10 mm high, or commonly greatly elongated by migration, up to several cm in length. Dictyosteliumgiganteum (not illustrated) 12. Sorocarps mostly 2-5 mm when erect, sorophores partially prostrate showing little taper, sori relatively large, 175-350 ~m in diameter with cupule-like residues at bases of sori Dictyostelium sphaerocephalum (Figs. 32-34) 12. Sorocarps mostly 2-5 mm when erect unlike the above. 13 13. Sorocarps becoming entangled in diffuse light, spores of collapsed sori germinate to form secondary sorocarps with basal discs. Dictyostelium implicatum (Figs. 8-10)13. Sorocarps not becoming entangled in diffuse light. 14

10. Botanica Helvetica 105/2, 1995 217

14. Sorocarps with slightly expanded conical bases. Dictyoste/ium mucoroides, S-type

(Figs. 2-4)14.

Sorocarps without expanded bases, aggregations assume a "lumpy" appearance in late stages,

sorogens elongated, sorophores migrating extensively. .Dictyoste/ium mucoroides, L-type

(Figs. 5- 7) 15. Sorocarpsclustered, aggregations usually mound-like. 18 15. Sorocarpssolitary or weakly clustered,aggregations usually mound-like. 16 16. Sporesoblong 3-4 x 6-81!m with numerousconspicuous unconsolidated polar granules. Dictyosteliumgermanicum (Figs. 50-52) 16. Sporessmaller mostly 2-3 x 4-61!m with inconspicuouspolar granules. 17 17. Sorophoretips capitate,coniferous or mixed coniferousdeciduous forest Dictyosteliumcapitatum (Figs. 53-55) 7. Sorophore tips not capitate, abundant in deciduous forest with acid humus Dictyosteliumminutum (Figs. 47 -49) 18. Sorocarpsin coremiform clusters,spores long, with numerousconspicuous unconsolidatedpolar granules. Dictyosteliumpolycarpum (Figs. 38-40) 18. Sorocarpsin irregular clusters,spores small and of two sizesboth with conspicuous consolidatedpolar granules. Dictyosteliummicrosporum (Figs. 41-43)

Discussion

With 19 species,the region studied in Germany has very similar speciesrichness to both the bistate region of Ohio and WestVirginia and the cool temperatezone of Japan. This could be the result of close similarity in the degreeof topographical, geographical and forest variation. Somespecies, are plentiful and common on all three continents,such as Dictyostelium mucoroidesS type, D. sphaerocephalum,D. minutum, Polysphondyliumpallidum and P. violaceum.Others are absent or very infrequent on one continent while they are prevalent on one or both of the others. The specieswhich are absent or relatively infrequent in Europe but common in North America and Japaninclude D. discoideum, D. purpureum,and D. polycephalum.Those absent or less frequent in Eastern North America but more common in Europe are P. candidum,P.filamentosum, D. polycarpum, D. septentrionalis,and D. implicatum.The last two speciesappear to be more common in the Pacific Northwest than elsewherein North America (Cavender,unpublished data). D. fasciculatumis an endemicto Europe. Three new speciesnot found in Switzerland or elsewherein Europe occur in Ger- many. One of these,D. capitatum,was isolated from a mixed coniferous-deciduousforest in the Harz mountains on the former border betweenEast and West Germany,while the second,D. germanicum,occurred in a deciduousforest in the Eifel region of Rhineland Palatinate.The most commonof the three, D. microsporum,was found at three separate coniferoussites. This is a fairly commonspecies in mixed coniferous-deciduousforest in Japan.- Coniferous forests with acid mor humus and deciduous forests with neutral or alkaline mull humus have distinct differences in their dictyostelid populations. Numbers 218 JamesC. Cavenderet al.

per gram are higher in deciduous forests, even those with acid soils, probably due to higher bacterial populations. Dictyostelium aureo-stipesvar. helvetium is an indicator species for coniferous forest. Other characteristic species are D. septen trionalis, and D. microsporum. Dictyostelium fasciculatum, D. polycarpum, P. candidum and D. aureo-stipes var. aureo-stipes are characteristic of deciduous forest with neutral or alkaline mull humus. Dictyostelium minutum is characteristic of deciduous forest with acid humus. Dictyostelium mucoroides S-type is dominant in most forests of Germany regardless of forest or humus type although it appears to be most prevalent in deciduous forest with mull humus and neutral or alkaline pH. Polysphondylium violaceum and Dictyostelium minutum may also dominate dictyostelid populations, the former in coniferous forest and the latter in deciduous forest with acid humus. The two sites with greatest species richness, Kaiserstuhl in the Black Forest region and Rothenburg on the Tauber river in central Germany, had mull humus with slightly alkaline pH. Yet two other sites with alkaline soil, Barbarossahohle south of the Harz mountains in the former East Germany and Wonsee in the Friinkische Schweiz mountains, had low speciesrichness. These sites appeared to have experienced greater anthro- pogenic disturbances. The highest numbers per gram were found in the Rothaargebirge near Siegen,a mixed forest with acid humus. This forest had speciescharacteristic of both acid coniferous and alkaline deciduous forest. Because of the high density and diversity of its dictyostelid populations this forest should be investigated further for other species. The lowest numbers per gram « 100) were in soils of four coniferous forests (spruce or pine) with acid humus. Again, this is most likely due to the lower densities of bacteria in mor humus.

The authors wish to thank Dr. Hiramitsu Hagiwara for examination of some of the isolates (ME-!, ME-2, TH-2, HE-4) and Kent Bares for assistancein collection of samples.

References

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