FAMILY THIORHODACEAE 



843 



dor Scliwefelbacterien, Leipzig, 188S, 

 104; Rhodothiosarcina rosea Ellis, Sul- 

 phur Bacteria, London and New York, 

 1932, 163.) From Latin roseus, rose- 

 colored. 



Cells spherical, 2 to 3 microns in diam- 

 eter, occurring in packets containing 

 8 to 64 cells. Infrequent motility. 

 Color ranging from purplish-rose to 

 nearly black. 



Anaerobic. 



Habitat : Mud and stagnant bodies of 

 water containing hydrogen sulfide and 

 exposed to light ; sulfur springs. 



Distribution: Probably ubiquitous. 

 One of the less frequent among the pur- 

 ple sulfur bacteria. 



Illustration: Issatchenko, Recherches 

 sur les microbes de I'ocean glacial arc- 

 tique, Petrograd, 1914, Plate II, fig. 5. 



Genus II. Thiopedia Winogradsky. 



(Zur Morphologie und Physiologic der Bacterien, I. Scliwefelbacterien, Leipzig, 

 i, 85.) From Greek theion sulfur and pedion, plane. 



Individual cells spherical to short rod-shaped, the latter shortly before cell divi- 

 sion. Arranged in flat sheets with typical tetrads as the structural units. These 

 arise from divisions of the cells in two perpendicular directions. Cell aggregates of 

 various sizes, ranging from single tetrads to large sheets composed of thousands of 

 cells. Motility infrequent. Non-spore-forming. Contain bacteriochlorophyll and 

 carotenoid pigments. Capable of photosynthesis in the presence of hydrogen sul- 

 fide, and then storing sulfur globules. Anaerobic. 



The type species is Thiopedia rosea Winogradsky. 



L Thiopedia rosea Winogradsky. 

 {Erythroconis littoralis Oerstedt, Na- 

 turhist. Tidskrift, 3, 18-10-1841, 555; 

 Merismopedia littoralis Pabenhorst, 

 Flora Europaea Algarum, Leipzig, 2, 

 1865, 57; Winogradsky, Zur )tIorphologie 

 und Physiologic der Schwefelbacterien, 

 Leipzig, 1888, 85; Pediococcus roseus 

 Trevisan, I generi e le specie delle Bat- 

 teriacee, Milan, 1889, 28; Latnpropedia 

 rosea DeToni and Trevisan, in Saccardo, 

 Sylloge Fungorum, 8, 1889, 1049; Plaiio- 

 coccus roseus Migula, in Engler and 

 Prantl, Die natiirlichen Pflanzenfami- 

 lien, 1, la, 1895, 19.) From Latin roseus, 

 rose-colored. 



Size: 1 to 2 microns, often appearing 

 as slightly elongated cocci regularly 

 arranged in platelets. Color, pale red 

 to nearly black, depending upon the 

 amount of sulfur stored. Red color 

 visible only with large cell masses, not 

 in individuals. 



According to Winogradsky, the cells 

 are often embedded in a common slime 

 capsule; the extensive studies of Uter- 

 mohl (Archiv f. Hydrobiol., Suppl. Vol. 



5, 1925, 251-276) make the regular occur- 

 rence of such capsules extremely doubt- 

 ful. On the other hand, Utermohl em- 

 phasizes as quite characteristic the 

 common presence of a relatively large 

 pseudovacuole, or aerosome, in the cells 

 of this species encountered in plankton 

 samples. Winogradsky does not men- 

 tion this; nevertheless, it appears to be 

 a regular and valualile distinguishing 

 feature. 



Anaerobic. 



Habitat: Mud and stagnant bodies of 

 fresh, brackish and salt water containing 

 hydrogen sulfide and exposed to light; 

 sulfur springs. 



Distribution: Ubiquitous. Common, 

 frequently giving rise to very extensive 

 mass developments. 



Illustrations: Warming, Videnskab. 

 Meddel. naturhist. Forening, Kjoben- 

 havn, 1876, Plate VIII, fig. 2; Winograd- 

 sky, loc. cit., Plate III, fig. 18; Prings- 

 heim, Naturwissensch., 20, 1932, 481, the 

 last one a truly excellent photomicro- 

 graph. 



