A NEW NEMATODE, OSTERTAGIA BULLOSA, PARASITIC IN THE ALIMENTARY TRACT OF SHEEP BY BRAYTON HOWARD RANSOM Assistant Custodian, Helminthological Collections, United States National Museum AND MAURICE C. HALL Assistant Zoologist, Bureau of Animal Industry, United States Department of Agriculture No. 1892. — From the Proceedings of the United States National Museum, Vol. 42, pages 175-179 Published February 28, 1912 Washington Government Printing Office 1912 A NEW NEMATODE, OSTERTAGIA BULLOSA, PARASITIC IN THE ALIMENTARY TRACT OF SHEEP BY BRAYTON HOWARD RANSOM Assistant Custodian, Helminthological Collections, United States National Museum AND MAURICE C. HALL Assistant Zoologist, Bureau of Animal Industry, United States Department of Agriculture No. 1892. — From the Proceedings of the United States National Museum, Vol. 42, pages 175-179 Published February 28, 1912 Washington Government Printing Office 1912 n AF ft- A NEW NEMATODE, OSTERTAGIA BULLOSA, PARASITIC IN THE ALIMENTARY TRACT OK SIIIOFOP. By.BRAYTON Howard Ransom, Assistant Custodian, 1 Ichninthological Collection*, thiiled States National Museum, Maurice C. Hall, Assistant Zoologist, Bureau of A trivial Industry, United Stales Department of Agriculture. The nematode described in this paper was first collected by the junior author at an abattoir in Colorado Springs, Colorado, April 28, 1911. Comparison with the descriptions of species given in Ransom (1911) led to the conclusion that the species was probably now. Specimens were then sent to the senior author who also was of the opinion that it was a new species. The sheep from which this ma- terial was collected were originally from the ranch of Mr. W. H. Wells near Resolis, Colorado, and specimens of the nematode here described wore collected by both of us dming the summer of 191 1 from sheep at Mr. Wells's ranch. The nematode was found in nearly every sheep examined at the ranch and was the only nematode found in the stomach with the exception of the stomach worm, JI;/m and the greatest number of Ihrmonclmx contortus, 537. Usually there were less than a dozen of each. This comparative freedom from infection with nematodes in Colorado sheep is to bo attributed in part to the dry climate and in part to the extensive area covered in range feeding, thereby preventing concen- tration of infection. Mr. W. D. Foster of the Zoological Division, Bureau of Animal Industry, has called our attention to a single specimen of a nematode, a female, collected by him May 13, 1910, from a sheep received in Proceedings U.S. National Museum, Vol. 42— No. 1892. 175 176 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 42. Washington from Montana. This specimen he had been unable to identify with any described species. Examination shows that it is of the same species as that collected by us in Colorado. Ostertagia bullosa is therefore known to occur in two of the Rocky Mountain States. Two other species of this genus have been found thus far only in the Rocky Mountain region, namely Ostertagia marslialli and 0. occidentalis, these two being reported heretofore only from Montana. To these records may be added our finding, in 1911, at a Denver abattoir, of 0. marshalli in sheep from Wyoming and Utah, and of 0. occidentalis in sheep from Wyoming. The new species is white when freshly collected and has the usual characteristics of the genus Ostertagia, but differs from other species of the genus in that the two ventral rays of each lateral lobe of the bursa are rather widely divergent, the spicules are simple and not split into several processes posteriorly, and the gubernaculum is of the same yellow-brown color as the spicules instead of being colorless. In the key given in Ransom (1911) this species runs down to Ostertagia trifurcata of which only the male is known. In several respects, however, it differs from trifurcata. The gubernaculum in 0. trifurcata is a narrow colorless structure, whereas in 0. bullosa it is a yellowish-brown structure, irregularly trihedral in shape. The spicules in 0. trifurcata are twisted but are not curved in their long axis, and are divided into 3 processes at the posterior end. The spicules in 0. bullosa are narrow, curving, tubular structures, not divided at the posterior end which is acutely pointed. Each of the two terminal branches of the dorsal ray in 0. trifurcata has a short process on the outer side and one on the inner. 0. bullosa has a short process on the outer side, but the process on the inner side is only sug- gested by a slight and often indistinct bifurcation at the tip. The principal characters of 0. bullosa are as follows: OSTERTAGIA BULLOSA Ransom and Hall, 1912. Specific diagnosis. — Ostertagia: Male (fig. 1) about 7.3 mm. long. Maximum thickness 115 p just in front of bursa. Diameter of head 17 p; diameter of body at level of nerve ring 44 to 48 p, at base of esophagus 68 a. Esophagus 510 to 545 p in length, surrounded by a nerve ring at a distance of 220 to 250 p from the anterior end. The excretory pore is situated about 270 p from the anterior end of the body. Cervical papilla? not evident. The esophagus increases in diameter from 16 p anteriorly to 45 or 50 p at its posterior end. The bursal membrane has a very distinct longitudinal striation. The median lobe is only slightly shorter than the lateral lobes. The lateral lobes are usually partly folded over each other in their ventral por- tions. The ventro-ventral (fig. 2, v. v.) and latero- ventral (fig. 2, 1, v.) no. 1892. A NEW PARASITIC NEMATODE— RANSOM AND HALL. 177 rays diverge considerably, which is unusual in the genus Ostertagia, and their tips are at least half as far apart as the tips of the latero- ventral and externo-lateral rays. The distance between the tips of the externo-lateral and medio-lateral rays is much less than that between the latter and the tip of the postero-lateral ray. Of the paired rays, the latero-ventral is the thickest- Following this in the order of size are Imm. I mm. \ 00 JUL. Fig. 1.— Osteetagia bullosa. Male and female. *vulva. enlarged. the externo-lateral (fig. 2, e.l.), then the medio-lateral (fig. 2, m. I.), the postero-lateral (fig. 2, p. I.), and the externo-dorsal (fig. 2, e. d.), which are of about the same size, and lastly the ventro-ventral. The dorsal ray (fig. 2, d.) is about 140