- B. Cells less than 3 microns in width.
2. Rhabdomonas gracilis.
II. Cells containing calcium carbonate inclusions in addition to sulfur globules.
3. Rhabdomonas linsbaueri.
1. Rhabdomonas rosea Cohn, 1875. (Cohn, Beitr. Biol. Pfl., 1, Heft 3, 1875, 167; Beggiatoa roseo-persicina Zopf, Z. Morphol. d. Spaltpflanzen, Leipzig, 1882, 30; Rhabdochromatium roseum Winogradsky, Schwefelbacterien, Leipzig, 1888, 100; Rhabdochromatium fusiforme Winogradsky, ibid., 102.)
ro′se.a. L. adj. roseus rosy, rose-red.
Cells uneven in width and length, often swollen to spindle-shaped, sometimes tending towards filamentous growth. The greatest width of a spindle-shaped or fusiform cell may be close to 10 microns; in the more filamentous structures it is usually around 5 microns. The length varies between 10 and 30 microns for single cells; filamentous forms, frequently showing bulges and constrictions suggestive of compound structures in which cell division has been incomplete, may attain considerably greater lengths, up to 100 microns. The ends of spindle-shaped cells often taper to very fine points or attenuated fibers; also, filaments are generally thinner toward the extremities. Single individuals and short filaments are motile by means of polar flagella, long filaments rarely motile. The ends of a filament may become pinched off and swim away.
Color rose-red; cells are usually filled with sulfur globules.
There is no good reason for maintaining Rhabdomonas fusiformis (Rhabdochromatium fusiforme Winogradsky) as a separate species; the variations in size and shape bring this form well within the range of Rhabdomonas rosea. Present indications strongly suggest that the latter species should be regarded as a peculiar developmental form of Chromatium okenii.
Habitat: Mud and stagnant water containing hydrogen sulfide and exposed to light; sulfur springs.
Illustrations: Cohn, op. cit., 1875, Pl. VI, fig. 14; Warming, Vidensk. Meddel. natur-histor. Foren., Kjöbenhavn, 1876, Pl. VII, fig. 1c-e; Zopf, op. cit., 1882, Pl. V, fig. 2b; Winogradsky, op. cit., 1888, Pl. IV, fig. 9-11, 13-14.
2. Rhabdomonas gracilis (Warming, 1876) Bergey et al., 1923. (Monas gracilis Warming, Vidensk. Meddel. naturhist. Foren., Kjöbenhavn, 1876, 331; Rhabdochromatium minus Winogradsky, Schwefelbacterien, Leipzig, 1888, 102; Rhodocapsa suspensa Molisch, Die Purpurbakterien, Jena, 1907, 17; Bergey et al.. Manual, 1st ed., 1923, 402.)
gra′ci.lis. L. adj. gracilis thin, slender.
Cells much smaller than those of Rhabdomonas rosea and with less tendency to form fusiform cells. Usually filamentous, more or less cylindrical, often with constrictions, but found up to 60 microns in length. Shorter filaments motile. Polar flagellate. Slime formation may occur under special conditions. Rose-red. Sulfur globules. Probably an abnormal growth form of Chromatium virosum.
Habitat: Mud and stagnant water containing hydrogen sulfide and exposed to light; sulfur springs.
Illustrations: Warming, op. cit., 1876, Pl. VII, fig. 5; Winogradsky, op. cit., 1888, Pl. IV, fig. 12; Molisch, op. cit., 1907, Pl. II, fig. 11-12.
3. Rhabdomonas linsbaueri (Gicklhorn, 1921) van Niel, 1948. (Rhabdochromatium linsbaueri Gicklhorn, Ber. d. deut. bot. Ges., 39, 1921, 312; van Niel, in Manual, 6th ed., 1948, 855.)
lins.bau′er.i. M.L. gen. noun linsbaueri of Linsbauer; named for K. Linsbauer, an Austrian botanist.
Cells resemble those of Rhabdomonas rosea, irregular, rod-shaped, 3 to 5 microns wide, up to 30 microns in length.
The characteristic feature of the species, and the chief means of differentiation, is the occurrence of calcium carbonate inclusions in addition to the sulfur globules in the cells. Whether this is strictly an environmentally conditioned characteristic, due to the photosynthetic development of the bacteria
