CTENASCAROPHIS-LESTERI N-SP AND PROSPINITECTUS-EXIGUUS N-SP (NEMATODA, CYSTIDICOLIDAE) FROM THE SKIPJACK TUNA, KATSUWONUS-PELAMIS

Two cystidicolid nematodes, Ctenascarophis lesteri n. sp. and Prospini tectus exiguus n. sp., are described from the skipjack tuna, Katsuwonu s pelamis, from Fiji, New Caledonia, Marquesas Islands, New Zealand, P apua New Guinea, and Puerto Rico. The former species differs from Cten ascarophis gastricus, the only other member of the genus, by having co mb rows extending farther posterior than two-thirds the body length, t o the anus in the female; it also has differently distributed spines o n each comb, with a maximum of 32 rather than 8. The male has 7 rows o f precloacal longitudinal crests; 3 pairs of precloacal, 1 pair adanal , and 6 pairs postcloacal papillae; and a spicule ratio of 1:3.4-1:5.0 . The latter species differs from Prospinitectus mollis, the only othe r species in the genus, by being less than one-half as long, 3.5-5.9 m m long; with a proportionally longer esophagus; fewer spines per spine ring, a maximum of 49 compared with 100; deirids that lack spinules; males with an unornamented precloacal cuticle as well as a different n umber and distribution of caudal papillae, 2 precloacal and 7 postcloa cal; and a smaller spicule ratio, 1:4 rather than 1:5-1:7.