Chaetogaster
Chaetogaster K. von Baer, 1827 (ref. ID; 1257, 3692, 6913, 7211)
Family Naididae (ref. ID; 1577, 1928, 5876, 5939, 6554, 7854)
Family Naididae: Subfamily Chaetogastrinae Sperber, 1948 (ref. ID; 1257, 7211)
ref. ID; 1663
Posterior end not with two lateral and one median process. Common and abundant everywhere. Dorsal setae completely lacking. Carnivorous. Mouth and pharynx large. (ref. ID; 1663)
ref. ID; 1923
Septa well developed; ventral setae "crotchet", with a swelling, the nodulus; without ventral hair setae. Penis lacking, gonads in some segments between 4 and 8; spermathecae in the same segments as the testes; lateral commisural blood vessels only in the anterior body segments. Without dorsal setae. (ref. ID; 1923)
- Chaetogaster annandalei Stephenson, 1917
See; Chaetogaster diastrophus (Gruithuisen) (ref. ID; 7098)
- Chaetogaster cristallinus Vejdovsky, 1883 (ref. ID; 1923, 3692, 6618, 6653, 6913) reported author and year? (ref. ID; 5939)
- Chaetogaster crystallinus Vejdovsky, 1883 (ref. ID; 1257, 1663, 3692, 6554) reported year? (ref. ID; 1577, 1928, 3446)
- Chaetogaster diaphanus (Gruithuisen, 1828) (ref. ID; 1257, 1663, 1923, 3692, 6554, 6913, 7098, 7854) reported year? (ref. ID; 1577, 1928, 3446) reported author and year? (ref. ID; 5939)
Syn; Nais diaphana Gruithuisen, 1828 (ref. ID; 3692)
- Chaetogaster diastrophus (Gruithuisen, 1828) (ref. ID; 1257, 1663, 1861, 1923, 3692, 7211, 7854) reported year? (ref. ID; 1577, 1928, 3446) reported author and year? (ref. ID; 5939)
Syn; Chaetogaster annandalei Stephenson, 1917 (ref. ID; 7098); Nais diastropha Gruithuisen, 1828 (ref. ID; 3692)
- Chaetogaster krasnopolskiae Lastockin, 1937 (ref. ID; 3692)
- Chaetogaster langi Bretscher, 1896 (ref. ID; 1257, 1663, 1923, 3692, 7854) reported year? (ref. ID; 1577, 3446) reported author and year? (ref. ID; 5939)
- Chaetogaster limnaei (ref. ID; 5939)
- Chaetogaster limnaei K. von Baer, 1827 (ref. ID; 1257, 1663, 1923, 3692, 6913, 7098, 7854) reported year? (ref. ID; 1928)
- Chaetogaster limnaei limnaei K. von Baer, 1827 (ref. ID; 5897) reported year? (ref. ID; 1577)
- Chaetogaster limnaei vaghini Gruffydd (ref. ID; 1577)
- Chaetogaster parvus Pointner, 1914 (ref. ID; 6618)
- Chaetogaster setosus Svetlov, 1925 (ref. ID; 1257, 3692) reported year? (ref. ID; 1577)
Chaetogaster cristallinus Vejdovsky, 1883 (ref. ID; 1923, 3692, 6618, 6653, 6913) reported author and year? (ref. ID; 5939)
Descriptions
Commissusal blood vessels ordinarily rudimentary on the pharynx; with an incision on the anterior margin of the prostomium (at times difficult to see). (ref. ID; 1923)
Chaetogaster crystallinus Vejdovsky, 1883 (ref. ID; 1257, 1663, 3692, 6554) reported year? (ref. ID; 1577, 1928, 3446)
Descriptions
Prostomium inconspicuous. Prostomium with median cleft. Chains of zooids 2.5 to 7.0 mm long. Up to six setae per bundle in II. (ref. ID; 1663)
This species is recorded by Prof. Hartog from Cork (tom. cit.), but as he described it as "a large species, revealing its structure under a pocket-lens," the record is somewhat dubious. (ref. ID; 1928)
Prostomium with a median incision. Chaetae in II, 11-12 per bundle, 158-162 µm. In the rest, 5-8, 100-135 µm with the upper teeth slightly longer than the lower, shorter and more curved than those of II. (ref. ID; 6554)
Remarks
Chaetal measurements conform well to the known range for this very transparent species. It has been considered synonymous with Chaetogaster diaphanus (see Brinkhust and Wetzel 1984), and the genus is in need of revision. (ref. ID; 6554)
New record
Argentina: San Juan River, San Juan Province, 14 May 1986, coll. E. Drago, U: Molet, 2 specimens. (ref. ID; 6554)
Chaetogaster diaphanus (Gruithuisen, 1828) (ref. ID; 1257, 1663, 1923, 3692, 6554, 6913, 7098, 7854) reported year? (ref. ID; 1577, 1928, 3446) reported author and year? (ref. ID; 5939)
Synonym
Nais diaphana Gruithuisen, 1828 (ref. ID; 3692)
Descriptions
Prostomium inconspicuous. Prostomium without median cleft. Setae more than 145 µm long in II. With more than six setae per bundle in II. (ref. ID; 1663)
Prostomium pointed. Dorsal chaetae absent. Ventral chaetae of II, 4-8 per bundle, 95-100 µm, the rest, 3-7, 62-74 µm. (ref. ID; 6554)
The prostomium of this species is inconspicuous, and the mouth is pursed in a fixed state. (ref. ID; 7098)
Remarks
As this species is almost crystal clear, and is also small (only 5 or 6 chaetigerous segments) and inactive, it may be frequently overlooked. It is probably cosmopolitan. The chaetal measurements fall within the normal range (Sperber 1948). It has been suggested as synonymous with Chaetogaster langi (see Brinkhurst & Wetzel 1984), but again this cannot be confirmed or denied without an overall revision of the genus. (ref. ID; 6554)
New record
Peru: Cienequilla on Lurin River, Depto. Lima, August 1970, coll. J. O'Neill, 20 specimens, W.J. Harman collection. (ref. ID; 6554)
Measurements
Length of worm 2.5-25 mm (ordinarily 10-15 mm); longest setae of segment 2 usually more than 200 µm. (ref. ID; 1923)
Chaetogaster diastrophus (Gruithuisen), 1828 (ref. ID; 1257, 1663, 1861, 1923, 3692, 7211, 7854) reported year? (ref. ID; 1577, 1928, 3446) reported author and year? (ref. ID; 5939)
Synonym
Chaetogaster annandalei Stephenson, 1917 (ref. ID; 7098); Nais diastropha Gruithuisen, 1828 (ref. ID; 3692)
Descriptions
See Chaetogaster limnaei limnaei (ref. ID; 1577)
Not epizoic on snalis or clams. Prostomium conspicuous. (ref. ID; 1663)
This species is common and widely distributed. (ref. ID; 1861)
Prostmium well developed, pointed with long sensory hairs, length 0.5-5 mm. (ref. ID; 1923)
The prostomium, though distinct, is not so prominent as Vejdovsky figured it. The chitinous plate, which lies at the back and under the brain is very conspicuous. There are 6-7 setae in a bundle, those on the second segment being considerably larger than the others. The nerve-cord has a very irregular outline, as though fringed with glandular outgrowths. The length is 1-2 mm; and the individuals consist of 10-12 segments. It is interesting to watch these worms working their way rapidly through close-set weeds. The anterior bundles of setae can be thrust forward, and expanded like a fan, and are used like claws, to drag the rest of the body forward. (ref. ID; 1928)
Remarks
Over 100 specimens collected from Lake Washington north of Mercer Island, Washington, had dorsal setae beginning in VI, opposite the second set of ventral setae, those in III-V being absent. This characteristic was noted by Hiltunen and Klemm (180) but Lafont (1981) erected the new taxon Pseudochaetogaster longmeri for similar material from France. We do not feel that action to be justified if based solely on this characteristic. Hiltunen and Klemm included C. langi Bret. as a synonym of C. diastrophus, but apparently overlooked the action of Kasprzak (1972) who synonymized C. crystallinus Vejd. with C. diaphanus (Gruit.). (ref. ID; 7211)
Chaetogaster langi Bretscher, 1896 (ref. ID; 1257, 1663, 1923, 3692, 7854) reported year? (ref. ID; 1577, 3446) reported author and year? (ref. ID; 5939)
Descriptions
Prostomium inconspicuous. Prostomium without median cleft. Setae less than 100 µm long. (ref. ID; 1663)
Commissural blood vessels ordinarily well developed on the pharynx; without an incision on the anterior margin of the prostomium. (ref. ID; 1923)
Chaetogaster limnaei K. von Baer, 1827 (ref. ID; 1257, 1663, 1923, 3692, 6913, 7098, 7854) reported year? (ref. ID; 1928)
Descriptions
Epizoic on surface or in mantle cavity of aquatic snails and fingernail clams (Sphaerium). Chain of zooids 2 to 6 mm long. Usually eight segments in first animal of a chain. (ref. ID; 1663)
Prostomium inconspicuous. Body length of worm 7 mm or less. Esophagus very short; ordinarily found living in the mantle cavity of pulmonate snails. (ref. ID; 1923)
Chaetogaster limnaei limnaei K. von Baer, 1827 (ref. ID; 5897) reported year? (ref. ID; 1577)
Descriptions
Important criteria for the distinction of the different species of Chaetogaster are, according to Sperber (1950), among others: form, number and length of the setae. Values for the dimension of the worm chains as well as number and length of the setae of segment II and VI. These two segments are the most important for taxonomic determination. The chains of Ch. diastrophus are somewhat longer than those of Ch. l. limnaei. The number of the setae in segment II and VI is significantly lower than in the Ch. l. limnaei populations examined, whereas the lengths of the setae lie within the confidence limits that are typical for Ch. l. limnaei as well. The arithmetic mean of the number and length of the setae is significantly higher in segment II than in segment VI in all three forms. Within the subspecies Ch. l. limnaei there are found significant differences on an intraspecific level in mean lengths of the bundles in segment II as well as in segment VI, whereas the number of setae did not vary significantly between populations. Both facts have already been found by Buse (1974) in populations from other host species. The variability within a given population of Ch. diastrophus is approximately as great as in the single populations of Ch. l. limnaei. On the other hand total variability within the two species is quite different. Newly formed setae bundles of the second animal of a chain have often not grown to full length when the separation of the two individuals begins. This might be one of the reasons for the natural variability within a population. On the other hand, the number of setae lies near the upper limit, that are give for segment II in Table 1. The second animal of each chain of Ch. diastrophus contained as an average 6.6 setae in each bundle (range: 6-7) and a mean length of 80.3 µm (range: 60-90 µm). Possibly, the new individuals develop initially that number of setae given as the upper limit of the range presented in Table 1, but lose setae later. Differences are found between the right and the left bundle on segment II of up to 3 setae. (ref. ID; 1577)
Habitats
Living on the outer surface of snails. (ref. ID; 1577)
Habitats
Living in the kidney of snails. (ref. ID; 1577)