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Title:Systematics of the stickcatfishes (Farlowella, Loricariidae)
Author(s):Retzer, Michael Eugene
Doctoral Committee Chair(s):Page, Lawrence M.
Department / Program:Biology, Zoology
Agriculture, Fisheries and Aquaculture
Discipline:Biology, Zoology
Agriculture, Fisheries and Aquaculture
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Biology, Zoology
Agriculture, Fisheries and Aquaculture
Abstract:The catfish genus Farlowella (Loricariidae) is a group of 25 species that morphologically and behaviorally mimics sticks and are widely distributed throughout the Amazon, Orinoco, Paraguay, and smaller Atlantic drainages in northern South America, including in the Maracaibo basin of Venezuela. Six species are new to science and are diagnosed, described, and contrasted to 19 previously described species.
Phylogenetic analysis using PAUP resulted in 42 trees of 65 steps. Nineteen species of Farlowella are placed in six species groups that are recognized as monophyletic groups in both strict consensus and majority rule (50%) consensus trees. Six species have uncertain relationships and are not placed in any group.
The breeding odontodes, snout length, and change in the number of scutes are of importance to reproduction and evolution of the sticklike appearance of Farlowella. Breeding odontodes on the side of the head have evolved from being large in F. curtirostra and F. taphorni, to small or medium in most species of Farlowella, to being absent in the F. amazona species group. Evolving a more sticklike form has involved lengthening the snout, lengthening and narrowing the body, and shortening the fins. In contrast, shorter snouts and bodies, wider and deeper bodies, and longer fins make the body less sticklike. Farlowella amazona and F. vittata are the most sticklike, and F. curtirostra, F. mariaelenae, F. nattereri, and F. taphorni, are the least sticklike.
The F. curtirostra species group lineage was separated from the ancestral population of Farlowella by the isolation of the Lago Maracaibo drainage by the Andean uplift 24 mya. The date of lineage separation suggests that the age of the genus is at least 24 million years old and that most of the diversification of genus occurred since the isolation of the Lago Maracaibo drainage.
Patterns of speciation among genera of fishes suggest that the enormous diversity of neotropical fishes is the result of different events. This evidence is contrary to the belief that single events (i.e., separation of the continents of Africa and South America; Pleistocene glaciation) account for much of the enormous diversity in the neotropical biota.
Issue Date:1994
Rights Information:Copyright 1994 Retzer, Michael Eugene
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9512527
OCLC Identifier:(UMI)AAI9512527

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