Two new nematode species of the genus Cosmocephalus Molin, 1858 (Spirurida: Acuariidae), with an amended generic diagnosis and an identification key to Cosmocephalus spp. Author Mutafchiev, Yasen Author Halajian, Ali Author Georgiev, Boyko B. text Zootaxa 2010 2349 1 20 journal article 10.5281/zenodo.193420 dd7f086e-6df6-4c73-a338-837cee1ab9e2 1175-5326 193420 Cosmocephalus jaenschi Johnston & Mawson, 1941 Material studied: One male specimen ( paratype , labelled ‘cotype’), AHC 21265, mounted in glycerine jelly, one slide; host: Phalacrocorax carbo L. ( Pelecaniformes , Phalacrocoracidae ); locality: Tailem Bend, South Australia . Redescription ( Fig. 7A, B ) Body length 11.0 mm. Maximum body width 228, about mid-body; width 97 at level of cloaca. Tail 293 long. Anterior end with two triangular pseudolabia, each bearing single amphid and pair of prominent papillae. Pair of swellings situated dorsally and ventrally at bases of pseudolabia. Cordons arise dorsally and ventrally between pseudolabia, extending in longitudinal direction to 371 from anterior body end, recurrent and anastomosing laterally at 102 from anterior body end ( Fig. 7A ). Each cordon consisting of a single row of cuticular plates (each c. 1.5 µm long) and longitudinal cuticular ridge along outer rims of plates; cuticular plates and longitudinal ridge delimiting deep, almost closed longitudinal groove. Maximum width of cordons 38. Deirids 18 long, tricuspid, at 453 from anterior body end. Excretory pore at 537 from anterior body end. Lateral alae well-developed, 17 wide, extending from level posterior of deirids to level about middle of body. Buccal cavity 389 long and 20 wide. Muscular oesophagus 929 long and 54 wide. Glandular oesophagus 3,770 long and 179 wide. Nerve ring at 421 from anterior body end. Cuticle 11–13 thick. Distance between cuticular striations 3–4 μm. Caudal alae 753 long. Single ventral cuticular ridge extending between level at 1,870 from posterior body end and beginning of caudal alae. Single median sessile precloacal papilla present. Nine pairs of pedunculate caudal papillae, 4 precloacal and 5 postcloacal ( Fig. 7B ). Anterior 3 pairs of postcloacal papillae with almost same distance between them; fourth pair at some distance from them; fifth pair at posterior end of tail. Sixth pair of postcloacal papillae sessile, smaller, situated between bases of last pedunculate papillae. Left spicule 672 long and 12 wide, with prominent projection on its distal end. Right spicule 159 long and 31 wide. Phasmids subterminal. I CL/BL 0.034; I mOE/gOE 0.249; I OE/BL 0.425; I CA/BL 0.068; I LSP/ RSP 4.226. Remarks. Cosmocephalus jaenschi was described on the basis of two male specimens obtained from Phalacrocorax carbo from Tailem Bend, Australia ( Johnston & Mawson 1941 ). Johnston & Mawson (1942) described a single female specimen collected from Pelecanus conspicillatus as belonging to C. jaenschi . They mentioned that the two males from P. c a r b o had tricuspid deirids; in contrast, the female identified as the same species had bicuspid deirids. This questions the identification of the female specimen described by Johnston & Mawson (1942) and we consider that the morphology of female of this species remains unknown. Johnston & Mawson (1941) did not mention the presence of lateral alae. Our study revealed the existence of lateral alae in the type material.