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Protistology 1 (2), 72-75 (1999) July, 1999
Protistology
The first isolation of Cochliopodium gulosum Schaeffer, 1926 (Lobosea, Himatismenida) since its initial description. I. Light-microscopical investigation
Alexander A. Kudryavtsev
Department of Invertebrate Zoology, Faculty of Biology and Soil Science, St. Petersburg State University, Russia
Summary
A marine lobose amoeba possessing characteristic features of the genus Cochliopodium (Hertwig and Lesser, 1874) Kudryavtsev, 1999 was found in the upper layer of sand at the beach of Keret Island, Kandalaksha Bay, the White Sea. Light-microscopical identity of this isolate and Cochliopodium gulosum Schaeffer, 1926 has been shown. This species has never been isolated and studied since its initial description. Its validity and generic position are confirmed by the results of light-microscopical investigation. Problems of biogeography of amoebae are briefly discussed.
Key words: amoebae, systematics, Lobosea, Himatismenida, Cochliopodium gulosum
The genus Cochliopodium (Hertwig and Lesser, 1874) Bark, 1973 comprises about 20 species of lobose amoebae (Bark, 1973; also see A.A.Kudryavtsev, in this issue). Among these species only 3 - C. bilimbosum (Auerbach, 1856) Leidy, 1879, C. minus Page, 1976 and C. larifeili Kudryavtsev, 1999 were studied with electron microscopy together with 3 unidentified strains which correspond to the diagnosis of this genus, but cannot be identified with any of known species (Bark, 1973; Nagatani et al., 1981). The majority of other species were never isolated since their initial description, and re-investigation of these species with modern techniques seems to be necessary. One of such species is Cochliopodium gulosum Schaeffer, 1926.
The results of its light-microscopical investigation and identification are presented here. This species was found in the samples of sand collected at the intertidal zone of the Keret Island (the Chupa Inlet, Kandalaksha Bay, the White Sea; salinity about 15-17%o) in September, 1997.
In locomotion amoebae were rounded or oval (Fig. 1-3), with length often slightly greater then breadth. Granuloplasmic hump was rounded and located centrally or, in rapid movement, post-centrally (when viewed from above; see Fig. 1-3). It was surrounded by a hyaloplasmic veil. The anterior margin of hyaloplasm was smooth (Fig. 1, 3) or with 2-3 to 10 subpseudopodia (Fig. 2), usually less then 10 pm in length. The posterior end of the body was smooth.
Length of the locomotive form varied from 56 to 90 pm (mean 80 pm), breadth, from 56 to 86 pm (mean 73 pm).
Amoebae had one spherical nucleus of vesicular type with large central nucleolus (Fig. 4). Diameter of nucleus varied from 8 to 15 pm (mean 12 pm), of nucleolus, from 6 to 10 pm (mean 8 pm). Granuloplasm contained large number of rounded refractive yellow crystals and minute transparent vesicles (Fig. 1). Sometimes food vacuoles with diatoms could be seen.
Scales constituting tectum were seen with light microscope as large conspicuous dots on the surface of the hyaloplasmic veil (Fig. 1-3). They were arranged in 1 layer more or less equidistantly from each other. Sometimes in locomotion, the anterior parts of hyaloplasm and subpseudopodia were not covered by tectum (Fig. 2-3).
Light-microscopical characters of this isolate correspond to the diagnosis of Cochliopodium gulosum designed by Schaeffer (1926; see tab. 1). The differences concerned only the set of cytoplasmic inclusions and interpretation of the appearance of tectum. Schaeffer stated that amoebae studied by him possessed «bluish-green refractory granules» but «no crystals could be demonstrated» (Schaeffer, 1926, p. 107). We suggest that these «refrac-tory granules» are identical with the crystals of amoebae described here. Judging from the text and illustrations of Schaeffer’s paper (Fig. 5), amoebae studied by him pos-
© 1999 by Russia, Protistology.
Figs. 1-4. Cochliopodium gulosum. Light-microscopical photographs. 1-2. Locomotive forms on glass surface (phase contrast). 3. Locomotive form on glass surface (differential interference contrast). 4. Haematoxylin stained preparation (bright field). H - hyaloplasm, G - granuloplasm, S - subpseudopodia, T - tectum, N - nucleus. Scale bar 10 pm throughout.
sessed tectum visible with light microscope which had the same appearance as that of amoebae described here, although Schaeffer (op. cit.) considered scales to be the minute granules located inside the cytoplasm, not on the surface of an amoeba.
Therefore, the amoeba strain studied in present work can be included in the genus Cochliopodium due to the presence of tectum (for modern generic diagnosis see A.A.Kudryavtsev, in this issue), and it would be identified as C. gulosum. In the combination of light-microscopical characters it differs from any of the previously described species of this genus (Archer, 1877; Korotneff, 1879;
Leidy, 1879; Penard, 1890, 1902, 1903; West, 1901; Page, 1976a) as well as from any of the unidentified strains studied by now (Bark, 1973; Nagatani et al., 1981). Thus, it can be considered to be a separate species within the genus Cochliopodium. Subsequently its diagnosis would be modified by the addition of electron-microscopical characters (in particular, the scale structure).
C. gulosum was initially found in the coastal waters of North America. Its isolation from the White Sea (NorthWestern Eurasia) confirms the idea of distribution of many species of amoebae at the territory ofboth continents (Page, 1976b). However, the biogeography of rhizopods remains
74 ■ Alexander A. Kudryavtsev
Fig. 5. Cochliopodium gulosum. Schematic drawing of the locomotive form (modified from Schaeffer, 1926). Scale bar 10 pm.
very poorly studied. Therefore, isolation of species from remote habitats is important for understanding the peculiarities of their distribution over the world.
Acknowledgements
I am grateful to Dr Alexey V. Smirnov for general supervision over the work and to Dr Andrew V Goodkov for valuable discussion of the manuscript. The collecting and preliminary treatment of the material were carried out at the Marine Biological Station of the Saint-Petersburg State University.
References
Archer W. 1877. Resume of recent contribution to our knowledge of «fresh-water Rhizopoda». Quart. J. Micros. Soc. 17, 330-353.
Bark A.W. 1973. A study of the genus Cochliopodium Hertwig and Lesser 1874. Protistologica. 9, 119-138.
Korotneff A. 1879. Etudes sur les Rhizopodes. Arch. Zool. Exp. Gen. 8, 467-482.
Kudryavtsev A.A. 1999. Description of Cochliopodium larifeili n. sp. (Lobosea, Himatismenida), an amoeba with peculiar scale structure, and notes on the diagnosis of the genus Cochliopodium (Hertwig and Lesser, 1874) Bark, 1973. Protistology. 1, (in this issue).
Leidy J. 1879. Freshwater Rhizopods of North America. Government Printing Office, Washington.
Nagatani Y., Yamaoka I. and Sato N. 1981. Scale structure of the external surface of an amoeba. Zool. Mag. 90, 112-115.
Page F.C. 1976a. An illustrated key to freshwater and soil amoebae. Freshwater Biological Association, Ambleside.
Page F.C. 1976b. Some comparative notes on the occurrence of Gymnamoebia (Protozoa, Sarcodina) in British and American habitats. Trans. Amer. Micros. Soc. 95, 385-394.
Table 1. Comparison of the characters given by Schaeffer (1926) for Cochliopodium gulosum with the characters of amoebae isolated from the White Sea
Character Schaeffer's description Characters of the White Sea isolate
1. Length of the locomotive form 80 ^m 56-90 |im (mean 80 |im)
2. Shape during locomotion Oval to circular with a "thin sheet of protoplasm" (hyaloplasm) surrounding the "main mass of protoplasm" (granuloplasm); "pseudopods" (subpseudopodia) on the outer edge of the sheet of protoplasm Oval to circular with granuloplasmic hump surrounded by hyaloplasmic veil with subpseudopodia at the anterior edge
3. Size and shape of the nucleus Nucleus spherical, 15 ^m in diameter, with "central chromatin mass" (nucleolus), 10 |im in diameter Nucleus spherical, 8-15 (12) |im in diameter, with large central nucleolus, 6-10 (8) ^ in diameter
4. Cytoplasmic inclusions Food vacuoles with diatoms, numerous small transparent vacuoles, "bluish-green refractory granules"; no crystals Food vacuoles with diatoms, numerous small transparent vacuoles, rounded refractive crystals
5. Appearance of tectum Small (less than 1 |im) pale granules filling the thin protoplasmic sheet surrounding the central mass of cytoplasm Conspicuous dots on the surface of the hyaloplasmic veil
Penard E. 1890. Etudes sur les Rhizopodes d’eau douce Mem. Soc. Phys. Hist. Nat. Geneve. 31, 1-230.
Penard E. 1902. Faune Rhizopodique du Bassin de Leman Henry Kuendig, Geneva.
Penard E. 1903. Notice sur les Rhizopodes du Spitzberg Arch. Protistenkd. 2, 238-282.
Address for correspondence: Alexander A. Kudryavtsev, Dept. of Invertebrate Zoology, Fac. of Biology & Soil Sci., St. Petersburg State University, 199034, Universitetskaja nab. 7/9 St. Petersburg, Russia.
E-mail: alexanderkudryavtsev@yahoo.com
Schaeffer A.A. 1926. Taxonomy of the Amebas. Carnegie Institution of Washington, Washington.
West G.S. 1901. On some British freshwater Rhizopods and Heliozoa. J. Linn. Soc. (Zool.). 28, 309-342.
The manuscript is presented by A.VGoodkov
