956 



ORDER I. RICKETTSIALES 



immune sera showed agglutination in dilu- 

 tions too low to be considered positive. 



9. Wolbachia sericea (Giroud and Mar- 

 tin, 1946) Philip, 1956. {Rickettsia sericea 

 Giroud and Martin, Bull. Soc. path, exot., 

 39, 1946, 264; Philip, Canad. Jour. Microbiol., 

 2, 1956, 267.) 



se.ri'ce.a. M.L. adj. sericeus silken. 



Minute, coccoid, diplococcoid and short 

 rods up to 0.5 micron in length. Violet with 



Giemsa's stain and red with Macchiavello's 

 stain. Bipolar staining may be observed. 



Cultivation: Not reported. 



Pathogenicity and source: Found both 

 extracellularly and intracellularly in 19 of 

 241 mites examined {Sericothrombium holo- 

 sericeum, a species which is not parasitic on 

 vertebrates in any stage). No longer con- 

 sidered pathogenic for the host mites. No 

 susceptibility was found in laboratory 

 animals. 



Genus VII. Symbiotes Philip, 1956. 



{Coivdnjia Macchiavello, Prim. Reunion Interamer. del Tifo, Mexico, 1947, 417; not Cowdria 



Moshkovskiy, Uspekhi Souremennoi Biol., 19, 1945, 18; Philip, Canad. Jour. 



Microbiol., 2, 1956, 267.) 



Although Cowdryia Macchiavello (1947) antedates Symbiotes Philip (1956), the former 

 generic name is an orthographic variant of an earlier generic name, Cowdria Moshkovskiy 

 (1945), and is therefore an illegitimate homonym. 



Sym.bi.o'tes. Gr. mas.n. symbiotes one who lives with a companion, a partner. 



Rickettsia-like, pleomorphic organisms living chiefly intracellularly in arthropod tissues 

 and approaching most nearly the true symbiotic or commensalistic relationship to their 

 hosts; this is evidenced by the development in the host of special organs, or mycetomes, 

 though no species of the Rickettsiales is yet known to be confined to such a location. 



The type species is Symbiotes lectularius (Arkwright et al.) Philip. 



1. Symbiotes lectularius (Arkwright et 

 al., 1921) Philip, 1956. (Rickettsia lectularia 

 Arkwright, Atkin and Bacot, Parasitology, 

 13, 1921, 35; Cowdryia lectularia Macchia- 

 vello, Prim. Reunion Interamer. del Tifo, 

 Mexico, 1947, 417; Symbiotes lectularia (sic) 

 Philip, Canad. Jour. Microbiol., 2, 1956, 

 267.) 



lec.tu.la'ri.us. M.L. adj. lectularius the 

 specific epithet of the common bedbug, 

 Cimex lectularius. 



Minute, pleomorphic, intracellular or- 

 ganisms, the typical form being coccoid or 

 diplococcoid, 0.2 by 0.4 to 0.5 micron, 

 staining deep purple with Giemsa's stain. 

 Bacillary, lanceolate and thread forms, 

 0.25 to 0.3 by 3.0 to 8.0 microns, occur which 

 stain more red than purple with Giemsa's 

 stain. Granules were reported in the thread 

 forms which were liberated during dark- 

 field examination. Motility of some of the 

 filamentous forms has been reported. The 

 possibility that a true bacterium occurs in 

 association has also been postulated. 



Cultivation : Attempts to grow this organ- 

 ism on cell-free media have been unsuccess- 



ful. However, Steinhaus (Jour. Bact., ^2, 

 1941, 757) cultivated, from- suitable host 

 sources, a diphtheroid in semi-solid media 

 and embryonated chicken eggs; the relation- 

 ship of the diphtheroid to this species was 

 uncertain. 



Pathogenicity and source: Found espe- 

 cially in paired, special organs, the myce- 

 tomes, in the common bedbug {Cimex 

 lectularius); also occurs in other tissues, the 

 alimentary tract, ovaries, testes, Malpighian 

 tubules and Berlese's organ. Transovarially 

 transmitted between generations and so 

 mutualistically adapted that it seems prob- 

 able that every bedbug harbors the organ- 

 ism. The same, or a related organism, was 

 observed in the swallow bedbug {Cimex 

 hirundinis) and in "accessory lobes" 

 (mycetomes?) in the tropical bedbug {Cimex 

 rotundatus). The only effect on the host was 

 reported as swellings in the Malpighian 

 tubules due to masses of organisms in the 

 cells, though destruction of such cells was 

 not noted. No effects were produced by in- 

 jection into laboratory animals and into 

 two human volunteers. 



