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R. HOEPPLE AND H. J. Chu,
Brues that the fauna, of thermal waters as a whole corresponds to a fauna typical of brackish water. Among the nematodes which have been found in thermal waters, there is a group the representatives of which are ubiquitous, that means that they have adjusted themselves to very different ecological conditions. It is, therefore, not surprising to find these forms in water of higher temperature. To this group belong: Mononchus brachyuris Bütschli var. macrodenticulatus Micoletzky; Mononchus macrostoma Bastian, 1865; Plectus parvus Bastian, 1865; Trilobus allophysis (Steiner), 1919; Aphelenchus parictinus Bastian, 1865; Chronoguster gracilis Cobb, 1913; Diploscapter coronata (Cobb), 1893.
Species which until the present have been found only in thermal water of a temperature higher than that of the atmosphere and which, there- fore, can be regarded to a certain degree as specific, are the following :- Dorylaimus therma Cobb, 1926; Dorylaimus atratus v. Linstow, 1901; Chromadora salinarum v. Linstow, 1901; Chromadora nanna Hoeppli, 1926; Microlaimoides setosus Hoeppli, 1926; Microlaimoides lingi, n. sp.; Greenia orientalis n. sp.; Cyatholaimus chungsani n. sp.; Monhystrella ginlingensis n. sp.; Monhystera filiformis var. fukienensis n. var, and Plectus chengmoh- liangi n. sp.
These species belong to genera which have representatives in salt water as well as in fresh water and soil with the exception of Plectus chengmohliangi; Plectus species have hitherto been reported only from fresh water and soil but have not been found in sea water.
In the genus Dorylaimus by far the majority of species live in soil and fresh water. On the other hand, most representatives of the genus Chromadora occur in salt water. Microlaimus, Monhystrella (close to Terschellingia) and Cyatholaimus species occur in about the same number of species in salt and in fresh water. The examination of these forms did not result in any morphological pecularity which could be considered due to the influence of a different thermal environment.
Regarding the species which have been exclusively reported from thermal waters, we find that the same or nearly related species occur in places which are geographically far distant from each other. There were found: Microlaimoides setosus in Yellowstone Park, Microlaimoides lingi in Fukien, China; Chromadora salinarum in Germany, Chromadora nanna in Yellowstone Park; Greenia orientalis (related to Plectus and Chromadora) in South, Central and North China; Cyatholaimus chungsani in Fukien, South China.
SUMMARY,
The nemic fauna of various hot springs in China and Formosa is not an ordinary fresh water fauna, because apparently some wide spread fresh water species do not occur in thermal waters. The nematode fauna of the springs examined is composed of two groups: (a) Ubiquitous species which normally occur under very different ecological conditions and which have probably a specially well-developed faculty of adjustment to different osmotic pressures and different temperatures. The first mentioned factor is
The Hong Kong Naturalist.
Free-Laving Nematodes from Hot Springs in China and Formosa,
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in our opinion more important than the second. (b) Species more or less specific for thermal waters belonging to a small number of genera which have mostly fresh water as well as marine representatives. These specific forms occur in identical or closely related species in thermal waters in different parts of the work.
No morphological pecularities due to the thermal environment could be found.
LITERATURE.
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Cobb, N. A. 1893. Nematodes, Mostly Australian and Fijian. Macleay Memorial Vol. Dept. Agric. New South Wales, Miscell. Publ. No. 13. Sydney.
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Steiner, G. 1917. Ueber das Verhältnis der marinen freilebenden Nematoden zu denen des Süsswassers und des Landes. Biol. Zentralbl., 37, No. 4.
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