Worm Breeder's Gazette 12(2): 14 (January 1, 1992)
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
"...diversity is esthetically enthralling." (Th. Dobzhansky, 1970)
As part of a coordinated effort to collect, identify and characterize rhabditid worms that are closely (and not so closely) related to Caenorhabditis elegans, we are compiling morphological, developmental and other data on some wild isolates from various sources. Necromenic ("waiting for the cadaver")(2) species have been isolated by dissecting surface-sterilized invertebrate hosts; other species have been isolated from soil samples using the Baermann funnel technique(3). Four of these species are presently available from the CGC (deposited by S.E.B.): Caenorhabditis vulgaris(4,5) (morphologically similar to C. remanei, it was found to be a different species on the basis of cross-mating tests(6)), Rhabditis sp.(5,7), Pellioditis sp.(5,7), and Pelodera sp.(5) (probably P. teres or a close relative(7)). Preliminary taxonomy was attempted using Andrassy's key(8), and we presently solicit advice from expert Rhabditidae zoologists (e.g., W. Sudhaus(7)). Brief descriptions and illustrations of these species are presented in this abstract; detailed descriptions, measurements and scaled illustrations are available on request.
[See Figure 1]
The metastom (arrow) of C. vulgaris bears a single large denticle that could have been formed by the fusion of two denticles (the probable ancestral state for this morphological character for most Caenorhabditis species(9)). The metastoms (arrows) of the Rhabditis and Pellioditis species bear about five minute bumps or "warts"; that of the Pelodera species bears three prominent denticles (note also the separated lips on the Pelodera species). All scale bars represent 10.0 µm.
[See Figure 2]
Work on elucidating the correct taxonomy of these species will continue with further characterizations of their development and anatomy. We anticipate that this growing collection of different species will prove invaluable for comparative studies at both morphological and molecular levels, and for species identifications by cross-mating.
2. Sudhaus, W., & Schulte, F. 1989. Nematologica 35:15-24.
3. Ayoub, S. M., 1977, as cited in Poinar, G. O., Jr., 1983. The Natural History of Nematodes (Prentice Hall, New Jersey) p. 87. We use KimWipes instead of filter paper, with great success.
4 Baird, S. E., Fitch, D. H. A., & Emmons, S. W. Caenorhabditis vulgaris n. sp. (Secernentea: Rhabditidae); an internal associate of pill bugs and snails. In preparation.
5. These species were originally deposited in the CGC under the names C. vulgariensis, R. terricola, R. maupasi and Cuticularia oxycerca, respectively, exemplifying the difficulties associated with correct taxonomy and identification for members of the Rhabditida based solely on the key. (7,8)
6 Baird, S. E., Sutherlin, M. E., and Emmons, S. W., 1992. Reproductive isolation in Rhabditidae (Nematoda:Secernentea); mechanisms that isolate six species of three genera. Evolution, in press.
7. Walter Sudhaus, Institut fur Zoologie, Freie Universitat Berlin, personal communication.
8. Andrassy, I., 1983. A Taxonomic Review of the Suborder Rhabditina (ORSTOM, Paris). Sudhaus, W., 1976. Zoologica 43: 1-229.