The nematode lungworms (suborder Strongylina) of North American deer of the genus Odocoileus .

1. Seven species of lungworms are so far known to occur in North American deer of the genus Odocoileus: Dictyocaulus filaria (Rudolphi, 1809) Railliet & Henry, 1907; D. viviparus (Bloch, 1782) Railliet & Henry, 1907; Varestrongylus alpenae (Dikmans, 1935) n.comb.; Pneumostrongylus tenuis n.sp.; Elaphostrongylus odocoilei Hobmaier & Hobmaier, 1934; Protostrongylus coburni Dikmans, 1935; and P. macrotis Dikmans, 1931. Specimens (from deer) of all these species except Dictyocaulus filaria and Protostrongylus coburni have been studied in the course of this work. 2. Two subspecies of Odocoileus virginianus (Boddaert) and two of O. hemionus (Rafinesque) have been reported as hosts for lungworms. These may be listed with their established lungworm parasites as follows: Common white-tailed or Virginia deer, Odocoileus v. virginianus (Boddaert): Dictyocaulus viviparus, Varestrongylus alpenae—new record, Pneumostrongylus tenuis—new record. Northern white-tailed deer, Odocoileus v. borealis Miller: Dictyocaulus filaria, D. viviparus, Varestrongylus alpenae, Protostrongylus coburni. Rocky Mountain mule deer, Odocoileus h. hemionus (Rafinesque): Dictyocaulus viviparus, Protostrongylus macrotis. Columbian black-tailed deer, Odocoileus h. columbianus (Richardson): Dictyocaulus filaria, D viviparus—new record, Elaphostrongylus odocoilei. 3. A new species, Pneumostrongylus tenuis, is based on a single male lungworm from a bronchiole of Odocoileus v. virginianus. Pneumostrongylus tenuis differs from P. calcaratus Monnig, 1932, genotype of Pneumostrongylus Monnig, 1932, in spicular, gubernacular, and bursal characters. 4. Pneumostrongylus alpenae Dikmans, 1935, is transferred to the genus Varestrongylus Bhalerao, 1932, as a result of the study of specimens of Pneumostrongylus alpenae and Varestrongylus pneumonicus Bhalerao, 1932, genotype of Varestrongylus. The former becomes Varestrongylus alpenae (Dikmans, 1935) n.comb. Also placed in this genus are Varestrongylus sagittatus (Mueller, 1890) n.comb. (syn. Strongylus, or Protostrongylus sagittatus) and Varestrongylus capreoli (Stroh & Schmid, 1938) n.comb. (syn. Protostrongylus capreoli). 5. The reports of Protostrongylus coburni from Odocoileus v. virginianus by Goble (1943) were based on larvae and adult lungworms in sections of lung tissue. Subsequent observations by Cheatum (in litt.) strongly indicate that these were actually Varestrongylus alpenae. 6. The structure of the gubernaculum in Protostrongylus macrotis is redescribed, and the conclusion reached that this form may be regarded as an aberrant species of Protostrongylus. Appendages at the distal ends of the gubernacular crura are given the name pedes (sing, pes), and the sclerotized are, found in the bursa of a number of genera of the Protostrongylinae, the name arcus. 7. The fact that crura have not been described for the gubernaculum of Elaphostrongylus cervi Cameron, 1931, genotype of Elaphostrongylus Cameron, 1931, whereas E. odocoilei Hobmaier & Hobmaier, 1934, possesses them must be regarded as a possibly significant difference between the two species; but it is suggested that E. cervi may be found to have these structures. Therefore E. odocoilei is left in Elaphostrongylus.