TABLE 1.

Description of Klebsormidium morphotypes from alpine soil crusts collected at different elevations.

Morphospecies	Strain	Elevation m a.s.l.	Description
K. flaccidum	ASIB V100	2,363	Filaments long, (7.8)8.1–8.5(9.3) × (7.3)10.7–14.3(17.8) μm, with tendency to disintegration, not or slightly constricted; cells cylindrical, (1)1.3–1.5(1.8) times as long as wide; cell wall moderately thickened; H-pieces present rarely; chloroplast covers 1/2–2/3 of the cell inner surface, with smooth margins, pyrenoid large, surrounded by several layers of starch grains. In liquid media forming superficial hydrorepellent layer and submerged tufts; on agar forming undulating colonies
K. cf. flaccidum	SIE1 SIE3 KUE1a KUE2 STU1	1,548 1,548 2,435 2,435 2,866	Similar to K. flaccidum, but with much stronger tendency to disintegration, especially in old culture, cells (6.5)7–8.3(11.7) × (4.0)5.7–12.1(13.2) μm, chloroplast usually with crenulated or irregularly dissected margins, appears to be intermediate between K. flaccidum and K. dissectum morphospecies
K. elegans	PIT1 PIT3	2,843 2,843	Filaments long, robust, (8)8.5–9.5(9.8) × (5)7.3–11.8(16.7) μm, sometimes growing in rope-like aggregates; cells cylindrical to barrel-shaped, (1.1)1.2–1.7 times as long as wide; cell wall moderately thickened; H-pieces present, prominent; chloroplast covering half to 3/4 of the cell inner surface, with a median incision in the margin, dissected in four or more lobes; pyrenoid large, surrounded by several layers of starch grains. In liquid media forming submerged tufts; on agar forming rough undulating colonies
K. crenulatum	AH1  (SAG 2415)b	2,350	Filaments long, strong, thick, (9.2)10–11.5 × (6.4)7.1–12.9(16.8) μm wide, sometimes growing in rope-like aggregates; cells cylindrical, becoming barrel-shaped and sub quadrate in old filaments, 0.5–1(1.5) times as long as wide; cell doublets occasionally present; cell wall initially thin, becoming thick and corrugated in old filaments; H-pieces common, prominent; chloroplast girdle-shaped, almost ring-like, covers most of the cell inner surface, with longitudinal margins smooth or slightly lobed; pyrenoid large, surrounded by several layers of starch grains. In liquid media forming only submerged tufts, on agar forming rough, undulating colonies
K. dissectum	BOT2  (SAG 2417)c BOT4	609 609	Filaments moderately long, but easily disintegrated, especially in mature and old cultures, (6)6.4–8.6(9.3) × (5.9)8.9–15.5(16.7) μm, slightly or distinctly constricted; cells cylindrical, often slightly swollen, in unicell stage ellipsoid or ovoid, (1.1)1.5–1.8(2.5) times as long as wide; cell wall moderately thickened; H-pieces usually absent; chloroplast covers 1/2–2/3 of the cell inner surface, with margins crenulated or irregularly dissected; pyrenoid somewhat large, surrounded by several layers of starch grains. In liquid media forming superficial hydrorepellent layer and submerged tufts; on agar forming homogeneous colonies with crenulate margins
K. nitens	OBE1d OBE2 RAU1 STR1 UEB	1,046 1,046 1,074 1,280 1,680	Filaments short, thin, (4.5)5–5.9(6.7) × (6.3)7.2–13.6(19.5) μm; easily disintegrated to unicells; cells cylindrical, constricted, 1.3–1.5(3) times as long as wide; cell wall thin; H-pieces usually absent; chloroplast covers 1/2–2/3 of the cell inner surface, with delicately lobed margins; pyrenoid small, surrounded by a layer of starch grains. In liquid culture forming submerged tufts and superficial layer; on agar forming smooth colonies
K. cf. nitens	PAT AH2  (SAG 2416)e OBG	2,145 2,350 2,350	Similar to K. nitens, but filaments thin to medium width, (5.3)5.6–6.8(7.8) × (6.3)7.2–10.9(13.6) μm; sometimes unicellular stage with ellipsoid cells and lobed chloroplast resembling Interfilum species
K. subtile	STU3 RAU2 BIR HOH1 HOH2 PIT2 VOE5f	649 1,074 1,953 2,207 2,207 2,843 2,866	Filaments long, with some tendency to fragmentation, medium width, in young culture cells are long and cylindrical, in mature and old cultures the cells become isodiametric (length/width—(0.8)1–1.3(1.8)), (5.4)6.0–6.8(7.6) × (4.7)5.8–10.3(13.1) μm, filaments are slightly bead-like, constricted near cross walls, H-like pieces sometimes present; chloroplast covers 2/3 of the cell inner surface, with smooth or waved margins; the pyrenoid is small, round, compact, surrounded by a layer of starch grains. In liquid culture forming submerged tufts and superficial layer; on agar forming smooth colonies
K. cf. subtile	STR2 STR3 SIE2g MUT	1,280 1,280 1,548 2,650	Similar to K. subtile, but filaments often fragmented and usually in mature culture have long, filaments and unicells, from thin to medium in width, (5.4)5.8–6.8(7.2) × (4.0)5.6–10.8(11.9) μm
K. fluitans	VOE2 VOE3d VOE4 VOE7 VOE8 ASIB V103h ASIB V108	649 649 649 649 649 2,363 2,363	Filaments long, strong, sometimes with tendency to disintegration, (6.5)7.5–8.8(10.7) × (6.6)7.1–11.5 (17.4) μm; cells cylindrical to isodiametric, slightly swollen, (0.6)0.9–1.4 times as long as wide; cell wall of medium thickness; H-pieces present; chloroplast covers 1/2–3/4 of the cell inner surface, with margins smooth or delicately crenulated; pyrenoid medium-sized, surrounded by several layers of starch grains. In liquid culture submerged tufts present; on agar forming growths with rough surface
K. cf. fluitans	BOT1 BOT3d RAU3d	609 609 1,074	Similar to K. fluitans, but in culture abundant thick filaments often present together with thin filaments similar to K. subtile morphotype, cell width (5.4)6.4–7.8(8.8) μm

^aStrain KUE1 was previously identified as transitional morphotype between K. flaccidum and K. dissectum, based on morphological characters (Karsten et al. 2013).

^bStrain AH1 (SAG 2415) was previously identified as K. crenulatum, based on morphological characters (Karsten et al. 2010, Holzinger et al. 2011) and rbcL phylogeny (Kaplan et al. 2012).

^cStrain BOT2 (SAG 2417) was previously identified as K. nitens, based on rbcL phylogeny (Kaplan et al. 2012).

^dStrains OBE1, VOE3, BOT3 and RAU3 were previously identified as K. fluitans, based on ITS phylogeny (Kitzing et al. 2014).

^eStrain AH2 (SAG 2416) was previously identified as K. dissectum, based on morphological characters (Karsten and Holzinger 2012).

^fStrain VOE5 was previously identified as a transitional morphotype between K. subtile and K. subtilissimum, based on morphological characters (Karsten et al. 2013).

^gStrain SIE2 was previously identified as a transitional morphotype between K. nitens and K. dissectum, based on morphological characters (Karsten et al. 2013).

^hStrain ASIB V103 was previously identified as K. fluitans, based on morphological characters (Karsten et al. 2013) and ITS phylogeny (Kitzing et al. 2014).