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Over 50% of imperiled fish species in Texas are endemic to the Rio Grande drainage. Bothriocephalus acheilognathi was recently collected from the Rio Grande and might pose further risk for these species. We examined the impact of this exotic tapeworm on fish condition and reproduction using a surrogate species, Cyprinella lutrensis. Fish were collected from two mainstem sites and one tributary site within Big Bend National Park from February through December 2006. Adjusted mean Fulton condition was higher for uninfected fish than infected fish. No differences were detected between uninfected fish for gonadosomatic indices, number of vitellogenic oocytes, number of late vitellogenic oocytes, late vitellogenic occyte maximum diameters, or proportion of late vitellogenic oocytes to total number of oocytes. These findings suggest that C. lutrensis is investing energy in reproduction at the expense of somatic growth, but energy invested in reproduction was not affected by tapeworm occurrence. [ABSTRACT FROM AUTHOR]

Mitochondrial DNA of nematodes undergoes frequent rearrangements, so it is a very good model for studying the mitochondrial genome evolution. The complete mitochondrial genome of a parasitic nematodeSenga ophiocephalinawas sequenced and annotated. The 13,816 bp-long genome contained 12 protein-coding genes (atp8gene was missing), two ribosomal RNAs, 22 transfer RNAs, and a 391 bp non-coding region. Phylogenetic analysis showed thatS. ophiocephalinaforms a monophyletic cluster with the remaining two Bothriocephalidae species. [ABSTRACT FROM PUBLISHER]