840 



ORDER VII. BEGGIATOALES 



shape; M.L. adj. leptomitiformis Leptomi- 

 tus-like. 



Trichomes, 1.0 to 2.5 microns in diameter, 

 of uniform width. Segments 4.0 to 8.0 mi- 

 crons in length; segmentation observable 

 only after removal of sulfur globules. Ter- 

 minal cells are usually rounded. 



Habitat : Found in fresh-water and marine 

 environments containing hydrogen sulfide. 



condition, they are of uniform width; bulg- 

 ing of the sides occurs under unfavorable 

 conditions. Trichomes clearly segmented. 

 Segments 5.0 to 13.0 (average, 8.5) microns 

 in length. Terminal cells are rounded or 

 tapered. 



Habitat : Apparently restricted to marine 

 environments containing hydrogen sulfide. 

 Frequently found on decaying marine algae. 



4. Beggiatoa minima Winogradsky, 

 1888. (Beitr. z. Morph. u. Physiol, d. Bac- 

 terien, I. Schwefelbacterien, 1888, 25.) 



mi'ni.ma. L. sup. adj. minimus least, 

 smallest. 



Trichomes, less than 1 micron in diame- 

 ter, of uniform width, normally appearing 

 unsegmented. Segments about 1 micron in 

 length. 



Habitat: Found in fresh-water and ma- 

 rine environments containing hydrogen 

 sulfide. 



5. Beggiatoa gigantea Klas, 1937. (Klas, 

 Arch. f. Mikrobiol., 8, 1937, 318; includes 

 the large forms of Beggiatoa mirahilis Cohn, 

 Hedwigia, 4, 1865, 81.) 



gi.gan'te.a. Gr. adj. giganteus gigantic. 



Trichomes 26.4 to 55.0 (average 35 to 40) 

 microns in diameter. Klas {op. cit., 1937, 

 318) gives 26.4 to 42.9 microns as the dimen- 

 sions, which would exclude the largest forms 

 of Beggiatoa mirahilis described by Hinze 

 (Ber. d. deut. bot. Ges., 19, 1901, 369). Since 

 the proposal of a separate species for such 

 organisms appears at present unjustified, 

 the maximum diameter has here been in- 

 creased. When the trichomes are in a healthy 



6. Beggiatoa mirahilis Cohn, 1865, 

 emend. Klas, 1937. (Cohn, Hedwigia, 4, 

 1865, 81; Klas, Arch. f. Mikrobiol., 8, 1937, 

 318.) 



mi.ra'bi.lis. L. adj. mirahilis marvelous. 



Trichomes 15.0 to 21.5 (average, 17.0) 

 microns in diameter. The so-defined species 

 does not overlap with Beggiatoa gigantea 

 according to Klas {loc. cit.). When the tri- 

 chomes are in a healthy condition, they are 

 of uniform width; an unfavorable environ- 

 ment induces bulging of the sides. Segments 

 5.0 to 13.0 (average, 8.5) microns in length; 

 segmentation usually observable without 

 special treatment. Terminal cells are 

 rounded or tapered, sometimes bent. 



Comment: Uphof (Arch. f. Hydrobiol., 

 18, 1927, 83) has recognized a species, Beg- 

 giatoa maxima, which, on account of its di- 

 ameter (10 to 20 microns) , falls partly within 

 the range of Beggiatoa mirahilis and partly 

 within Beggiatoa arachnoidea. Since it was 

 found in a fresh-water environment, the 

 habitat of Beggiatoa mirahilis may not be 

 restricted to marine media. 



Habitat: Apparently restricted to marine 

 environments containing hydrogen sulfide. 

 Common on decaying marine algae. 



Genus II. Thiospirillopsis Uphof, 1927. 

 (Arch. f. Hydrobiol., 18, 1927, 81.) 



Thi.o.spi.ril.lop'sis. M.L. neut.n. Thiospirillum a genus of bacteria; Gr. noun opsis ap- 

 pearance; M.L. fem.n. Thiospirillopsis that which has the appearance of Thiospirillum. 



Colorless sulfur bacteria occurring in segmented and spirallj^ wound trichomes. Exhibit 

 a creeping motility combined with rotation so that the trichomes move forward with a 

 corkscrew-like motion. The tips may oscillate. Resembles Spirulina among the Oscilla- 

 toriaceae. 



The type species is Thiospirillopsis floridana Uphof. 



1. Thiospirillopsis floridana Uphof, 

 1927. (Arch. f. Hydrobiol., 18, 1927, 83.) 



flo.ri.da'na. M.L. adj. fioridanus per- 

 taining to Florida. 



