OBSERVATIONS ON THE MORPHOLOGY OF TRUTTAEDACNITIS-CLITELLARIUS AND TRUTTAEDACNITIS-LEBEDEVI (NEMATODA, CUCULLANIDAE) FROM ACIPENSERIDS AND SYNONYMY OF THE 2 SPECIES
A. Choudhury et Ta. Dick, OBSERVATIONS ON THE MORPHOLOGY OF TRUTTAEDACNITIS-CLITELLARIUS AND TRUTTAEDACNITIS-LEBEDEVI (NEMATODA, CUCULLANIDAE) FROM ACIPENSERIDS AND SYNONYMY OF THE 2 SPECIES, Systematic parasitology, 33(2), 1996, pp. 89-99
Truttaedacnitis clitellarius (Ward & Magath, 1917) (Nematoda: Cucullan
idae) is redescribed from the lake sturgeon Acipenser fulvescens from
North America and compared with T. lebedevi (Skrjabina, 1966) from the
Siberian sturgeon A. baeri. Studies on the morphology and morphometri
cs of the two species reveal considerable overlap with unique shared c
haracters, such as the previously unreported position of the excretory
pore at the level of the pseudobuccal capsule and arrangement of caud
al papillae. This position of the excretory pore is anteriormost among
all cucullanids. Although there is a trend towards smaller size of bo
dy and spicules in T. lebedevi, this reflects a long period of geograp
hical separation and likely accounts for the minor morphological varia
tions noted. Consequently, the two species are synonymised. The presen
ce of one species of Truttaedacnitis, T. clitellarius, specific to fre
shwater acipenserids in North America and Siberia, suggests an ancient
origin and slow rare of evolution for this cucullanid.