Evolutionary morphology of trichomycterid catfishes: about hanging on and digging in

The catfi shes (Siluriformes) comprise a particularly diverse teleost clade, from a taxonomic, morphological, biogeographical, ecological and behavioural perspective. The Neotropical Trichomycteridae (the “parasitic” catfi shes) are emblematic of this diversity, including fi shes with some of the most specialized habits and habitats among teleosts (e. g. hematophagy, lepidophagy, miniaturization, fossorial habitats, altitudinal extremes). Relatively little information is available on general trichomycterid morphology, as most work so far has concentrated on phylogenetically informative characters, with little concern about general descriptive anatomy. In this paper we provide a synthesis of new and previously-available data in order to build a general picture of basal crown group trichomycterid morphology and of its main modifi cations. We focus on the evolutionary morphology in two relatively distal trichomycterid lineages, i. e. the hematophagous Vandelliinae and the miniature, substrate dwelling Glanapteryginae. New evidence is discussed in relation to the evolution of the opercular system as well as morphological modifi cations in miniature species exhibiting an interstitial life style.