A New Nonparasitic Species of the Holarctic Lamprey Genus Lethenteron Creaser and Hubbs, 1922, (Petromyzonidae) from Northwestern North America with Notes on Other Species of the Same Genus

A new nonparasitic lamprey, Lethenteron alaskense from Alaska and Northwest Territories is described and illustrated. The holotype (No. NMC 76-614) is deposited in the National Museum of Natural Sciences, Ottawa, Canada. The study was based on 67 metamorphosed specimens. The species, by its permanently non-functional intestinal tract and weak dentition, smaller disc and much smaller size (maximum 188 mm), is easily separable from the parasitic Lenthenteron japonicum (maximum length 625 mm) found in the same areas. It is distinguishable from nonparasitic L. lamottenii, found in eastern and southern North America, by 1) a generally weaker dentition but possessing more anterials and supplementary marginals; 2) typically with five velar tentacles as opposed to seven in L. lamottenii; 3) differences in pigmentation pattern of the second dorsal fin and a lack of dark pigmentation on the gular region; 4) smaller size in comparison to 299 mm maximum length in L. lamottenii; and 5) distinct areas of geographical distribution separated from each other by 2400 km. All three, L. alaskense, L. lamottenii, and L. japonicum have usually 66 to 72 trunk myomeres. L. alaskense, by its higher number of myomeres is separable from two other nonparasitic species: L. reissneri from Asia with less than 64 myomeres and L. meridionale from eastern tributaries of the Gulf of Mexico with 50 to 58 myomeres

A New Nonparasitic Species of Lamprey of the Genus Entosphenus Gill, 1862, (Petromyzonidae) From South Central California

A new nonparasitic lamprey from the Friant-Kern Canal, east of Delano, California, is described and illustrated. The holotype (number CAS 35987) is deposited in the California Academy of Sciences, San Francisco, California. The species is distinguishable from all species of the genus Entosphenus by: 1) low number of trunk myomeres — 53 in the ammocoete and between 54 and 57 (average 55.5) in transformed specimens, whereas in other species the range is 58-73; 2) reduced dentition with typical numbers of teeth — 2 supraoral cusps, 1-1-1-1 inner lateral teeth on each side of the disc, 9-12 (average 10.3) posterial teeth; 3) only 3 velar tentacles, whereas in other species the number of tentacles varies from 5 to 18; 4) small size of transformed specimens, 117-142; and 5) restricted distribution. The description is based on the study of eleven newly transformed individuals and one ammocoete