Figures (6)  Tables (1)

    • Figure 1. 

      (a) The amoebae of D. discoideum persist across the organism's complete life cycle. (b) The steps involved for observing spores.

    • Figure 2. 

      Examples of different dictyostelid spore shapes (all the images are from the corresponding references). (a) Dictyostelium globisporum spores. Bar = 5 μm[18]. (b) D. minimum spores. Bar = 10 µm[19]. (c) Heterostelium equisetoides. Bar = 10 μm[20]. (d) Cavenderia boomerangispora, long and frequently curved PG+. Bar = 10 μm[23]. (e) H. naviculare, elongated navicular spores with consolidated polar granules. Bar = 5 μm[27]. (f) H. flexuosum, relatively small spores, note the widely distributed, numerous unconsolidated granules. Bar = 10 μm[23]. (g) D. polycarpum, group of spores with polar spore granules PG. Bar = 5 μm[30].

    • Figure 3. 

      Microscopic features (shape and granules) of spores used in the identification of dictyostelid species.

    • Figure 4. 

      Examples of different dictyostelid spore granules (all the images are from the corresponding references). (a) Dictyostelium robusticaule. Bar = 20 μm[34]. (b) Heterostelium stolonicoideum, oblong spores note the conspicuous unconsolidated polar granules. Bar = 10 μm[23]. (c) Raperostelium cymosum, large elliptical, mostly reniform spores with conspicuous consolidated polar to subpolar granules. Bar = 6 μm[37]. (d) Cavenderia fulva, elliptical spores with prominent refractive consolidated granules at their poles. Bar = 5 μm[37]. (e) R. ibericum. Bar = 10 μm[38]. (f) C. minima, small elliptical irregular spores with polar to subpolar consolidated granules, generally the cluster of granules appears larger at one of the poles. Bar = 6 μm[37]. (g) D. capillare, elliptical spores with conspicuous, consolidated polar granules. Bar = 5 μm[32]. (h) D. unicornutum, broadly elliptical spores with polar and subpolar granules. Bar = 5 μm[32]. (i) C. bhumiboliana, rather large, elliptical spores with consolidated polar granules. Bar = 10 μm[39]. (j) Hagiwaraea irregularibrachiatum, elliptical short spores with small unconsolidated polar to subpolar granules. Bar = 6 μm[37].

    • Figure 5. 

      The current classification used for dictyostelids[36].

    • Figure 6. 

      Dictyostelids rely on animal vectors for spore dispersal in many instances. (a) Noctuid moth. (b) Snail. (c) Sparrow. (d) Eastern chipmunk. (e) Turtle.

    • Species Morphological state (consolidated vs unconsolidated) Distribution
      (polar, subpolar,
      dispersed)      		 Visibility (conspicuous vs inconspicuous) Special structures
      (e.g., halos, refractive features)      		 Others Ref.
      Dictyostelium ammophilum ! ++ (Occasionally +) Romeralo et al.[40]
      D. capitatum + – Hagiwaia[41]
      D. dichotomum Mostly + ++ to + + Vadell & Cavender[14]
      D. gargantuum – On the surface Vadell et al.[42]
      D. germanicum Mostly – + On the surface Cavender et al.[43]
      Polysphondylium violaceum + + Vadell and Cavender[15]
      P. aureum + + + Hodgson & Wheller[44]
      P. fuscans – + Perrigo[45]
      P. patagonicum + Mostly + + Vinaceous Vadell et al.[42]
      Raperostelium ibericum Mostly +, some – – + One or more relatively
      large granules      		 Romeralo et al.[38]
      R. australe Polar to subpolar/
      dispersed      		 + Cavender et al.[46]
      R. cymosum + ++ to + + Cavender et al.[37]
      R. maeandriforme + ! + Some with a heterogeneous content Cavender et al.[32]
      Acytostelium anastomosans Central + Cavender et al.[27]
      *A. subglobosum Distinctively different
      from other species due to inconsistently scarce,
      minute granulation and clearly recognizable zonation      		 Cavender & Vadell[16]
      Heterostelium anisocaule – + Cavender et al.[46]
      H. luridum – Mostly throughout
      the cytoplasm      		 Kauffman et al.[47]
      H. migratissimum Median + ++ and + + Cavender et al.[8]
      H. parvimigratum Mostly + Not consistently ++ or +, – Cavender et al.[8]
      H. radiatum ++ – Perrigo et al.[48]
      H. rotatum Mostly – – (the largest at
      the poles)      		 Landolt et al.[23]
      H. stolonicoideum Mostly – ++ Landolt et al.[23]
      H. tikalense – ++ Vadell & Cavender[15]
      Cavenderia ungulata + ++ + Often surrounded by
      a clear narrow halo      		 Large Cavender et al.[49]
      C. pseudoaureostipes + Mostly ++, sometimes +
      or with – smaller granules      		 Surrounded by clear halos Many rounded Vadell et al. [39]
      C. antarctica + ++ to + + Sometimes unipolar, smallest individuals lack granules Cavender et al.[46]
      C. nanopodia + + Irregular in shape and size Vadell & Cavender[14]
      C. fasciculata ++ or + + Traub et al.[30]
      C. fasciculoidea + ++ + Surrounded by a clear halo Visible as angular units Vadell et al.[42]
      C. fulva 1–2 large + ++ to +,
      sometimes –      		 Cavender et al.[37]
      C. macrocarpa + ++ to + Vadell & Cavender[14]
      *C. minima Heterogeneous content (often one much larger cluster of granules at one pole with halos, plus tiny dispersed granules) Cavender et al.[37]
      *C. subdiscoidea + ++ Dense, round, with clear halos Duringdormancy—spores enlarge when in contact with humid substrate, making the spore body heterogeneous and granules larger Vadell et al.[39]
      C. helicoidea – ++ Cavender et al.[49]
      Special cases are indicated by an asterisk '*', consolidated '+', unconsolidated '−'; polar '++', subpolar '+', dispersed '−'; conspicuous '+', inconspicuous '−'; concurrence '!'.

      Table 1. 

      Species of dictyostelids containing polar particles along with their sources and original literature descriptions.