MARCH 1962 / VOL. 40 / NO. 3 An lchthydium, Probably Sulcatum of the Mountain Lake, Virginia Area by CHARLES E. PACKARD Rumania, Russia, Switzerland and the Randolph-Macon College United States. Remane (4) listed 8 Ashland, Virginia species but made no mention of I. sulca- tum Stokes. Probably the form most frequently mentioned in the literature is I. podura Muller of 1773. A National Science Foundation grant Stokes (1) described the gastrotrichan received through the auspices of the "Icthydium sulcatus" from Trenton, New University of Virginia made study and Jersey, as follows: "The characteristic research possible at its Mt. Lake Biologi- of this form is the deep transverse fur- cal Station in Giles County, Virginia, rows conspicuously developed on the back during the summers of 1958 and 1960. and sides. The body is transparent, and A number of smooth and near-smooth unusually soft and flexible. The posterior species of gastrotrichs were found in the region, between the arch of the back and marshy areas near the station buildings the caudal furcation, is narrowed, and and in Mountain Lake itself. Several of much longer than in other species. The these animals regularly showed a rippled esophagus is short, being not more than body surface which seemingly appeared one-sixth of the length of the body." He and disappeared as a temporary feature reported similar observations as early as of the gross body form. However, several 1887. Is this a valid species? instances were encountered where the Brunson (2) published a more exten- oddly ringed, or "segmented" annulation, sive account of "Ichthydium sulcatum so conspicuous in many coelhelminths on Stokes", which he collected in July, 1944, the larger scale, was constant. All at- in Michigan, figuring the same, thus tempts to cultivate such organisms in strengthening the finding of Stokes. artificial media over more than a few "Smooth" gastrotrichs were observed by days failed. Individuals bearing resem- the author in New Hampshire, Maine, blance to Ichthydium are here selected New York, and Virginia from the early from the total of 176 gastrotrichs isolated nineteen thirties through the succeeding for data recordings during the months of years. No decision was ever reached as June, July and the first part of August to whether there was or wasn't a clear-cut 1958. pattern of cuticular thickenings and Although "rippled" forms were seen variously-shaped markings resembling true as early as the second week in June, scales. specimen #106, isolated from a collec- Murray (3) has said that Joblot in tion taken at the Mountain Lake north 1718 seemingly was first to see and de- shoreline, containing many small water scribe a gastrotrich that was later to plants growing submerged on the rocks, become the genus Ichthydium. Since then on July 18, seemed clearly to be of the members of the genus have been reported Ichthydium sulcaturn type. It was very widely but very intermittently from all slim and streamlined as were others noted, continents except Australia, including possessing features which reminded one such loci as Bulgaria, Ceylon, England, of Heterolepidoderma species. Overall Germany, Hungary, Nubia, Paraguay, length was 133.2 microns, esophagus being 82 • Turtox News Vol. 40, No. 3, March, 1962 C) 1962, General Biological Supply House, Inc. 33.3 long. toes 16.65. The posterior end Toes were arched in side view, slender, was distinctly narrowed this part being clear with rounded ends. Ventral ciliation only slightly longer than the esophagus. was dense but short throughout. Circular sulcations were very definite, Esophagus and narrowed posterior end being visible even under low magnifica- were the same length and a little over a tion. The animal was well ciliated ven- fourth of the entire extent. The posterior trally, had two pairs of dorsal "hairs" dorsal pair of hairs was located very far projecting stiffly from the surface, the back at the end level of the intestine. foremost measuring as much as the "toes", They showed the same queerly reflexed tip. the hindmost being reflexed at the tip. Specimen #122, examined 7123, from The head was clearly 5-lobed, bearing a the lake collection made earlier in the shield and subterminal mouth, also a pair week, was 149.85 microns. Its features of lateral, clear vesicles. The intestine were very much as its predecessor's. was darkly granular. A greatly elongated However, #106 moved about leisurely egg, rounded and blunt posteriorly, whereas this animal darted and snapped extended well beyond the esophageal- its body like a minnow. Intestine was intestinal junction. It showed lobulations. very dark but the body had a yellowish Mouth width was 3.33 microns, head cast. Esophagus here was rounded at its width 23.31. Tiny bits of crushed glass junction with the intestine hut the pre- supported the cover slip. The animal was vious form showed these two structures a rapid swimmer and darter. Its curious meeting in a truncate line. The mouth body form resembled that of a very here was ribbed or "beaded", a condition slender woman in a hobble skirt. With not previously noted. The extent from evaporation of the water drop the body side to side of the frontal shield was 6.66 flattened and thickened. There seems microns. strong likelihood that the organism was Specimens 128 and 129 were recovered very closely akin to the I. sulcatum of on 7/28 at a slightly different locus on both Stokes and Bronson. the shore, beside the small boat-wharf, On 7/19/58 specimen #116 was re- by a large rock at the left of the Lakeside covered for measurement, from a collec- House going northeast. Data were meager. tion taken from Nunn's small pasture The diagnosis made was "probably I. pond in the western part of Giles County, sulcatum". a mate to this being seen. Data are: Specimen #164, taken from the marshy (microns), overall length, 129.87; esoph- area close to the laboratory, on 8/8, ageal length, 29.97; narrowed posterior seemed most elongated of any of these zone, 16.65 long, 11.1 wide; body width smooth species. measuring about 173 16.65; toe spread the same; head width microns although there was difficulty in 17.76; neck width 14.43. The intestine making a completely accurate determina- was again coarsely granular and there tion. In this creature delicate transverse was a small anterior shield. stripings were noted in the esophagus, From a morning collection taken at the also a sort of notched or jointed condi- lakeshore with abundant water plants tion halfway down the slender caudal scraped from the stones, on 7/21, a third prolongations. specimen very similar to both of the pre- Throughout the series of studies there ceding was isolated into methocel and occurred examples where various delicate supported by glass bits. Overall length cuticular patterns seemed to be present. reached about 159 microns. Head was The gastrotrichs were strongly similar in large for body width, mouth small but gross structure but varied in some de- prominent, shield present. Lateral vesi- tails. At the University of Maine in the cles, attenuated posterior end, spread toes, nineteen thirties when studies were pros- and relatively short esophagus were well ecuted, such smooth and near-smooth defined. The body tapered very gradually. types were found. The genus Heterolepi- Vol. 40, No. 3, March, 1962 Turtox ews • 83 doderma has kept coming to mind and it tude is hereby expressed to Dr. H. H. has become increasingly desirable that Hobbs, director of the station during the more satisfactory cultivation methods be summers of 1958 and 1960. and to all devised whereby isolated clones could be others for the many courtesies and favors had for observation. This may be the shown. surest and safest way of determining whether a given gastrotrich is or is not a references valid species inasmuch as many slight 1. Stokes—,k. C.: Aquatic Microscopy, p. 195 ff., variations may occur within a population. John Wiley, 1918. Would the grooves, so evident in some 2. Brunson, R. B.: An Introduction to the Tax- animals, and so much suggested in others onomy of the Gastrotricha with a Study of Eighteen Species from Michigan. Trans. Am. without being permanent seemingly, per- Micr. Soc. 69: 325 N., 1950. sist through a succession of generations 3. Murray, J.: On the Gastrotricha. Jour. Quek. unmodified by varying environmental con- Micr. Club, 2d series 12, p. 211, 1913-15. 4. Remane, A.: Gastrotricha. Bronn's Klassen ditions? It is hoped that analyses on und Ordnungen des Tierreichs. 4 Abt. 2, data accumulated may be presented in Buch 2, Tiel 2, Lfg. 1-2, 1-242. 1935-36. future papers. There is evidence that a member or some members of the genus Heterolepidoderma, apparently unreported from the United States, may have been had. Smooth species have been cultivated but not in such numbers nor for a length of time sufficient to warrant critical re- porting. Late July and early August of the summer of 1960 at Mountain Lake were characterized by low precipitation and almost no moisture at all in the formerly soggy and wet marshy area near the laboratory. Numerous collections from the lake at the same loci visited in 1958 showed a considerable number of chaeto- notids but not the rich and abundant fauna of 1958. No circularly ringed forms occurred from the samples of water plants secured by scouring the stones. 1 20A55-D Many samples were also taken from "Lake Rana", the small frog pond on the station grounds fed by the water course from Riker Mount Salt Pond Mountain, but very few gastro- trichs were found. Data from the 1960 for Botanical Specimens season are being processed.