A New Water-Mite of the Genus Stygomomonia (Family Momoniidae)Author(s): Rodger MitchellSource: Transactions of the American Microscopical Society, Vol. 78, No. 2 (Apr., 1959), pp.154-157Published by: Wiley on behalf of American Microscopical SocietyStable URL: http://www.jstor.org/stable/3224023 .

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ROBERT P. HIGGINS ROBERT P. HIGGINS

1936. Tardigrada. Das Tierreich 66: 1-340. 1946. Batillipes pennaki, a new marine tardigrade from the North and South

American Atlantic coast. Com. Zool. Mus. Hist. Nat. Montevideo, 2: 1-3. MATHEWS, G. B. 1938. Tardigrada from North America. Amer. Midi. Nat..

19: 619-626. PACKARD, A. D. 1873. Discovery of a tardigrade. Amer. Nat., 7: 740-741. PEARSE, A. S. (ed.) 1949. Zoological names. A list of phyla, classes, and orders.

24 pp. Durham. PENNAK, R. W. 1940. Ecology of the microscopic Metazoa inhabiting the sandy

beaches of some Wisconsin lakes. Ecol. Monogr., 10: 537-615. 1953. Tardigrada. In Fresh-water invertebrates of the United States. ix+

769 pp. New York: Ronald Press Co. PETERSEN, B. 1951. The tardigrade fauna of Greenland. A faunistic study with

some few ecological remarks. Medd. Gr0nland, 150: 1-94. WHITTAKER, R. H. and FAIRBANKS, C. W. 1958. A study of plankton copepod

communities in the Columbia Basin, southeastern Washington. Ecology, 39: 46-65.

A NEW WATER-MITE OF THE GENUS STYGOMOMONIA (FAMILY MOMONIIDAE)

RODGER MIICHELL

Biology Dept., University of Florida

Stygomomonia, marked by an unexplainable modification on the front legs, is among the wonderfully specialized inhabitants of deep stream gravels and subsurface waters. Although the fauna of such waters is well-known in Europe and has been the subject of recent studies in Japan (Imamura, 1957) it remains unstudied in the New World. The mites from gravels in the upper reaches of cold, permanent streams in Vermont indicate that there are Holarctic genera restricted to subsurface waters. A new species occurs in the Vermont collections which possesses a peculiar structure of special interest.

Two species are known, Stygomomonia latipes Szalay from central Europe (Viets 1955) and S. rotunda Imamura (1957) from Japan. A third name, S. riparia, has been validated by Habeeb (1957) who recorded a few measurements of one female from New Brunswick; a specimen probably belonging to that species is considered below.

Stygomomonia moodyi n. sp. Distinguished from all known species by the presence of only two

obscure, small setae on the lateral margin of coxa IV, the bold foveate sculpturing of all the body plates, the extension of coxae I and II posterior to the capitulum, and the short terminal segments of leg I.

Diagnosis: Body encased by complete dorsal and ventral shields marked by strong foveate impressions; dorsum with six evenly-spaced pairs of dorsoglandularia around its margin; a single lateroglandularia free in

1936. Tardigrada. Das Tierreich 66: 1-340. 1946. Batillipes pennaki, a new marine tardigrade from the North and South

American Atlantic coast. Com. Zool. Mus. Hist. Nat. Montevideo, 2: 1-3. MATHEWS, G. B. 1938. Tardigrada from North America. Amer. Midi. Nat..

19: 619-626. PACKARD, A. D. 1873. Discovery of a tardigrade. Amer. Nat., 7: 740-741. PEARSE, A. S. (ed.) 1949. Zoological names. A list of phyla, classes, and orders.

24 pp. Durham. PENNAK, R. W. 1940. Ecology of the microscopic Metazoa inhabiting the sandy

beaches of some Wisconsin lakes. Ecol. Monogr., 10: 537-615. 1953. Tardigrada. In Fresh-water invertebrates of the United States. ix+

769 pp. New York: Ronald Press Co. PETERSEN, B. 1951. The tardigrade fauna of Greenland. A faunistic study with

some few ecological remarks. Medd. Gr0nland, 150: 1-94. WHITTAKER, R. H. and FAIRBANKS, C. W. 1958. A study of plankton copepod

communities in the Columbia Basin, southeastern Washington. Ecology, 39: 46-65.

A NEW WATER-MITE OF THE GENUS STYGOMOMONIA (FAMILY MOMONIIDAE)

RODGER MIICHELL

Biology Dept., University of Florida

Stygomomonia, marked by an unexplainable modification on the front legs, is among the wonderfully specialized inhabitants of deep stream gravels and subsurface waters. Although the fauna of such waters is well-known in Europe and has been the subject of recent studies in Japan (Imamura, 1957) it remains unstudied in the New World. The mites from gravels in the upper reaches of cold, permanent streams in Vermont indicate that there are Holarctic genera restricted to subsurface waters. A new species occurs in the Vermont collections which possesses a peculiar structure of special interest.

Two species are known, Stygomomonia latipes Szalay from central Europe (Viets 1955) and S. rotunda Imamura (1957) from Japan. A third name, S. riparia, has been validated by Habeeb (1957) who recorded a few measurements of one female from New Brunswick; a specimen probably belonging to that species is considered below.

Stygomomonia moodyi n. sp. Distinguished from all known species by the presence of only two

obscure, small setae on the lateral margin of coxa IV, the bold foveate sculpturing of all the body plates, the extension of coxae I and II posterior to the capitulum, and the short terminal segments of leg I.

Diagnosis: Body encased by complete dorsal and ventral shields marked by strong foveate impressions; dorsum with six evenly-spaced pairs of dorsoglandularia around its margin; a single lateroglandularia free in

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A NEW WATER-MITE

the lateral membrane at about the posterior three-fourths of the body; ventral shield and coxae fused, with the line of fusion usually marked by internal coxal apodemes; three evenly spaced pairs of ventroglandularia along the margin of the ventral shield, one pair of ventroglandularia posterior to coxae IV. Coxae. All coxae fused; all but coxae IV meeting mesally, each delimited by internal apodemes; coxae I fused mesally and, together with coxae II, extend posteriorly to the base of the capitulum; coxae IV with slightly angulate mesal margins, lateral margins not defined by apodemes; two very small setae along the lateral margin of the coxa. Legs: Unmodified except for swollen segments 5-6 of leg I; segment 1-5

FIGS. 1-2 Stygomomonia moodyi n. sp.: venter; mesal aspect segments 5-6, leg I. FIGS. 3-4 S. ? riparia Habeeb: venter; mesal aspect segments 5-6, leg I.

expanded basally and slightly narrowed distally, with only a few un- modified terminal setae; segment 1-6 ovoid with a large dorsal incision in which the dorsally projecting tarsal claw lies, with four heavy setae on the mesal surface and a similar chaetotaxy on the lateral surface; tarsal claw hooked and pointing dorso-posteriorly; surface of leg segments with light reticulate markings. Genital Field. In the female the pair of genital plates lie lateral to the gonopore, bearing three acetabula; posterior to these a pair of short broad plates bearing two ventroglandularia; male genital plates each with three acetabula, fused with ventral shield, acces- sory glandularia plates lying free of the ventral shields.

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RODGER MITCHELL

Measurements: (average of type series) Dorsal shield, 0.48 mm. long, 0.38 mm. wide; leg segment 1-5, 0.128 mm. long by 0.047 mm. wide; leg segment I-6, 0.064 mm. long, 0.046 mm. wide.

Specimens. Holotype Female; Addison Co., Vermont, New Haven River two mi. south of Lincoln. IX.30.1956. Paratypes; one female, same data as holotype. One female Chittenden Co., Vermont, Preston Brook 212 m. southeast- of Jonesville, IX.14.1956. One male, one female Washington Co., Vermont, Downsville Brook at Waterbury, IX.10.1956. Two females Chittenden Co., Vermont, Mill Brook 512 mi. southeast of Jericho, IX.4.1954.

Discussion. Stygomomonia moodyi is of particular interest because it is rather unlike any of the known species of the genus all of which form a compact, obviously closely related group. Very marked differences in the form of the coxae and modifications of leg I separate the known species from S. moodyi and it is of interest to note that this new form is somewhat closer to the genera Momonia and Momoniella than other Stygomomonia. The similarities are not so marked, however, as to have any necessary phylogenetic significance.

It is a pleasure to name this species for Prof. Paul A. Moody of the University of Vermont.

Stygomomonia ? riparia Habeeb Four genital acetabula; mesal margins of coxae IV angulate; body

plates marked by delicate groups of alveoli; five conspicuous setae along the lateral margin of coxae IV and terminal segments of leg I very elongate.

Diagnosis: Shields with light alveolate impressions slightly coarser than those of S. latipes; dorso-glandularia boldly marked and a latero- glandularia in the usual position; ventral shield continuous with coxae III and IV but separated from the anterior two coxae by a suture; large prominent ventroglandularia. Coxae. First two coxae fused and free, their meso-posterior projections barely meeting at the mid line; coxae III broadly triangular in form; coxae IV with mesal margins parallel for some distance. Legs. Unmodified except for segments 5-6 of leg I; segment I-5 swollen basally and slightly tapering distally; segment I-6 relatively elongate with a dorsal projection basally and a broad dorsal depression in which the large bifid tarsal claw lies; setae of segment 6 fine and elon- gate. Genital Field. Of normal form except for four acetabula.

Measurements. Dorsal shield, 0.49 mm. long, 0.36 mm. wide; leg segment I-5, 0.202 mm. long, 0.051 mm. wide; leg segment 1-6, 0.081 mm. long, 0.041 mm. wide.

Specimen. One female, Chittenden Co., Vermont, Mill Creek 512 mi. southeast of Jericho, IX.4.1954.

The identity of this species cannot be made definitely until the type is made available or properly described. Measurements and number of acetabula are all that Habeeb gave in his description and the above specimen agrees with these few characters.

DISCUSSION Inhabitants of the interstitial waters of gravel can never be observed

adequately and certainly the problems facing such animals are difficult to appreciate. Some features of Stygomomonia are obvious; their lack of

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A NEW WATER-MITE A NEW WATER-MITE

pigment and their hydrophilic integument, which traps the animal at the water-surface, are characteristic of subterranean and deep water forms respectively, neither of which are ever exposed normally to the problem of contacting the air-water interface.

The most perplexing feature of the Momoniidae is how they use their peculiarly modified fore legs. Since both sexes and all the genera have similarly modified legs the function is probably one that requires a very specific device. After observing specimens Angelier (1933) was con- vinced that the function was tactile and S. latipes, with a leg similar to that in figure 4 does have hairs that are obviously sensory. S. moodyi lacks the long fine hairs, however, but still retains the essential morphology of leg segment I-6 (Fig. 2). This example of variation in tactile structures but with uniform mechanical relationships suggests an additional function for the leg.

Mechanically, the claw of the first leg, may anchor the animal or it may be used for feeding. The lack of any muscle development in the coxae and basal segments is good evidence that the first leg has not taken over a major part of the locomotor functions, for it has been shown that coxal apodemes are generally reliable indicators of the strength of leg action. It thus appears probable that both sensory and mechanical functions are carried out by leg I.

LITERATURE CITED ANGELIER, E. 1953. Recherches ecologiques et biog6ographiques sur la faune des

sables submerges. Arch. Zool. Exper. et Gen., 90: 37-161. HABEEB, H. 1957. New Hydrachnellae from North Carolina. Leafl. Acad. Biology,

No. 15, 8 pp. IMAMURA, TAIJI. 1957. Subterranean Water-Mites of the Middle and Southern

Japan. Arch. f. Hydrobiol., 53: 350-391. VIETS, KARL. 1955. In subterranen Gewassern Deutschlands lebende Wassermilben.

Arch. f. Hydrobiol., 50: 33-63.

NEW PARASITE RECORDS FROM STICKLEBACK AND SALMON IN AN ALASKA STREAM

OLIVER B. COPE U. S. Fish and Wildlife Service, Denver, Colorado

Some new fish parasite records were made during the course of fishery investigations in Alaska in the summer of 1947. The host fish, three-spine stickleback (Gasterosteus aculeatus Linn), king salmon (Oncorhynchus tshawytscha (Walbaum) ), and red salmon (Oncorhynchus nerka (Walbaum) ), were found in Otter Creek on the military reservation at Fort Richardson, Anchorage, Alaska. Otter Creek is tributary to Eagle Bay, an arm of Cook Inlet. Additional host and parasite material was collected for the author by Mr. David Sleeper in the summer of 1948.

Three parasites were found in abundance on Otter Creek fish, each

pigment and their hydrophilic integument, which traps the animal at the water-surface, are characteristic of subterranean and deep water forms respectively, neither of which are ever exposed normally to the problem of contacting the air-water interface.

The most perplexing feature of the Momoniidae is how they use their peculiarly modified fore legs. Since both sexes and all the genera have similarly modified legs the function is probably one that requires a very specific device. After observing specimens Angelier (1933) was con- vinced that the function was tactile and S. latipes, with a leg similar to that in figure 4 does have hairs that are obviously sensory. S. moodyi lacks the long fine hairs, however, but still retains the essential morphology of leg segment I-6 (Fig. 2). This example of variation in tactile structures but with uniform mechanical relationships suggests an additional function for the leg.

Mechanically, the claw of the first leg, may anchor the animal or it may be used for feeding. The lack of any muscle development in the coxae and basal segments is good evidence that the first leg has not taken over a major part of the locomotor functions, for it has been shown that coxal apodemes are generally reliable indicators of the strength of leg action. It thus appears probable that both sensory and mechanical functions are carried out by leg I.

LITERATURE CITED ANGELIER, E. 1953. Recherches ecologiques et biog6ographiques sur la faune des

sables submerges. Arch. Zool. Exper. et Gen., 90: 37-161. HABEEB, H. 1957. New Hydrachnellae from North Carolina. Leafl. Acad. Biology,

No. 15, 8 pp. IMAMURA, TAIJI. 1957. Subterranean Water-Mites of the Middle and Southern

Japan. Arch. f. Hydrobiol., 53: 350-391. VIETS, KARL. 1955. In subterranen Gewassern Deutschlands lebende Wassermilben.

Arch. f. Hydrobiol., 50: 33-63.

NEW PARASITE RECORDS FROM STICKLEBACK AND SALMON IN AN ALASKA STREAM

OLIVER B. COPE U. S. Fish and Wildlife Service, Denver, Colorado

Some new fish parasite records were made during the course of fishery investigations in Alaska in the summer of 1947. The host fish, three-spine stickleback (Gasterosteus aculeatus Linn), king salmon (Oncorhynchus tshawytscha (Walbaum) ), and red salmon (Oncorhynchus nerka (Walbaum) ), were found in Otter Creek on the military reservation at Fort Richardson, Anchorage, Alaska. Otter Creek is tributary to Eagle Bay, an arm of Cook Inlet. Additional host and parasite material was collected for the author by Mr. David Sleeper in the summer of 1948.

Three parasites were found in abundance on Otter Creek fish, each

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