Two new species of deepwater plecs have been described by ichthyologists Nathan Lujan and Carine Chamon.
The two new species have been caught from the deep main channels of rivers and are named Hemiancistrus pankimpuju and Panaque bathyphilus in a recent issue of the journal Ichthyological Exploration of Freshwaters.
Hemiancistrus pankimpuju is known from the Maraon River (in the Amazon River drainage) and is distinguished from congeners in having a smaller eye, elongate filaments on the caudal fin and lacking an iris operculum.
This species is named after the white colour of the type specimens, from ~pankim meaning beautiful and ~puju meaning white in the language of the Aguaruna people indigenous to northern Peru.
Panaque bathyphilus, by Nathan Lujan.
Panaque bathyphilus is distinguished from congers in having a combination of elongate filaments on the caudal fin, deep body, small eyes, shorter interorbital distance and caudal peduncle depth.
This species is known from the Solimes River (in the Amazon River drainage) and is named after the deep river channel habitat of this species .
Hemiancistrus pankimpuju has been exported in the trade as L350 and Panaque bathyphilus as L90.
Although both species are originally distinguished from their respective congeners as lacking pigmentation, pigmented forms of these species exist and are more common in the trade (the de-pigmented type specimens are the result of their living in deep water).
The authors also mention and discuss the hypothesis that the long caudal filaments may be a mechanosensory adaptation for detection and avoidance of predators approaching from behind.
They also discuss other deepwater adaptations (such as the absence of an iris operculum) in loricariids seen in both species.
For more information, see the paper: Lujan, NK and CC Chamon (2008) Two new species of Loricariidae (Teleostei: Siluriformes) from main channels of the upper and middle Amazon Basin, with discussion of deep water specialization in loricariids. Ichthyological Exploration of Freshwaters 19: 271"282.