A Revision of the South American Fishes of the Genus Nannostomus Giinther (Family Lebiasinidae)
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A Revision of the South American Fishes of the Genus Nannostomus Giinther (Family Lebiasinidae) STANLEY H. WEITZMAN and J. STANLEY COBB SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY • NUMBER 186 SERIAL PUBLICATIONS OF THE SMITHSONIAN INSTITUTION The emphasis upon publications as a means of diffusing knowledge was expressed by the first Secretary of the Smithsonian Institution. In his formal plan for the Insti- tution, Joseph Henry articulated a program that included the following statement: "It is proposed to publish a series of reports, giving an account of the new discoveries in science, and of the changes made from year to year in all branches of knowledge." This keynote of basic research has been adhered to over the years in the issuance of thousands of titles in serial publications under the Smithsonian imprint, com- mencing with Smithsonian Contributions to Knowledge in 1848 and continuing with the following active series: Smithsonian Annals of Flight Smithsonian Contributions to Anthropology Smithsonian Contributions to Astrophysics Smithsonian Contributions to Botany Smithsonian Contributions to the Earth Sciences Smithsonian Contributions to Paleobiology Smithsonian Contributions to Zoology Smithsonian Studies in History and Technology In these series, the Institution publishes original articles and monographs dealing with the research and collections of its several museums and offices and of professional colleagues at other institutions of learning. These papers report newly acquired facts, synoptic interpretations of data, or original theory in specialized fields. These pub- lications are distributed by mailing lists to libraries, laboratories, and other interested institutions and specialists throughout the world. Individual copies may be obtained from the Smithsonian Institution Press as long as stocks are available. S. DILLON RIPLEY Secretary Smithsonian Institution SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY • NUMBER 186 A Revision of the South American Fishes of the Genus Mannostomus Gtinther (Family Lebiasinidae) Stanley H. Weitzman and J. Stanley Cobb SMITHSONIAN INSTITUTION PRESS City of Washington 1975 ABSTRACT Weitzman, Stanley H., and J. Stanley Cobb. A Revision of the South American Fishes of the Genus Nannostomus Giinther (Family Lebiasinidae). Smithsonian Contributions to Zoology, number 186, 36 pages, 34 figures, 1975.—Based on newly collected material, this study is a supplemental treatment to an earlier review of the South American genus Nannostomus by the senior author. Eleven species are here recognized, N. espei, N. digrammus, N. harrisoni, N. beckfordi, N. bifasciatus, N. minimus, N. marginatus, N. trifasciatus, N. marilynae (new), N. unifasciatus, and N. eques. An artificial key to all these species is included. Additional collections of two species, N. bifasciatus and N. minimus, have allowed a more complete description of the former and recognition of the latter, which had been listed as a synonym of N. beckfordi by Weitzman (1966). One new species, N. marilynae, is described from the Amazon basin. The interrelationships of all the species are reconsidered and because the new material has revealed intermediate conditions in the characters formerly used to separate the nominal genera Nannostomus and Poecilobrycon, the latter is here regarded as a synonym of the former. Relationships among the species are not clear from the population samples currently available for study, but it seems probable that N. espei, in the aggregate of its characters, is the most primitive species in Nannostomtis and not closely related to any other species. N. marginatus and N. trifasciatus, undoubt- edly closely related to each other, are not particularly close to any other species or species group. The same may be said for the related N. eques and N. unifas- ciatus in their relation to other species. The remaining species all seem distinct from one another and their possible relationships to other species in the genus remain obscure. Evolutionary trends toward specialization within the genus appear to be devel- opment of longitudinal stripes, development of oblique bands, loss of ossification of the sensory canal in the second infraorbital bone, an elongation and thicken- ing of the anal-fin rays of males as an aid to fertilizing eggs, possibly the develop- ment of an ocellus in the dorsal lobe of the caudal fin, and development of nuptial tubercles on the ventral surface of the head. Thickening of anal-fin rays occurs to a certain extent in other lebiasinids, but it is carried to an extreme in some species of Nannostomus. Nuptial tubercles occur in another lebiasinid genus, Pyrrhuh'na, but their high concentration on the ventral surface of the head in Ar. unifasciatus is a specialization not found in Pyrrhulina. OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is recorded in the Institution's annual report, Smithsonian Year. SI PRESS NUMBER 5186. SERIFS COVER DESIGN: The coral Montastrea cavernosa (Linnaeus). Library of Congress Cataloging in Publication Data Weitzman, Stanley H. A revision of the South American fishes of the genus Nannostomus Giinther (family Lebiasinidae) (Smithsonian contributions to zoology, no. 186) Supt. of Docs, no.: SI 27:186 1. Nannostomus. 2. Fishes—South America. I. Cobb, J. Stanley, joint author. II. Title. III. Series: Smithsonian Institution. Smithsonian contributions to zoology, no. 186. QL1.S54 no. 186 [QL638.L3] 591'.08s [597'.521 ISBN 74-11317 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 - Price SI.10 (paper cover) Contents Page Introduction . 1 Classification of the Family Lebiasinidae . 2 Genus Nannostomus Giinther 3 Artificial Key to the Species of Nannostomus . 6 Nannostomus espei (Meinken) 7 Nannostomus digrammus Fowler 9 Nannostomus harrisoni (Eigenmann) 11 Nannostomus beckfordi Giinther 14 Nannostomus bifasciatus Hoedeman 16 Nannostomus minimus Eigenmann 21 Nannostomus marginatus Eigenmann . 25 Nannostomus trifasciatus Steindachner 27 Nannostomus marilynae, new species 29 Nannostomus unifasciatus Steindachner 33 Nannostomus eques Steindachner 33 Sumario . 35 Literature Cited 36 A Revision of the South American Fishes of the Genus Nannostomus Giinther (Family Lebiasinidae) Stanley H. Weitzman and J. Stanley Cobb Introduction To help the aquarist identify these popular aquarium fishes, as well as to illustrate the differ- Since publication of a review (Weitzman, 1966) ences between the color patterns of live and pre- of the nominal lebiasinid genera Nannostomus and served specimens, we have included drawings as Poecilobrycon, the senior author has accumulated well as photographs of preserved specimens where specimens of several of the known species from new appropriate. In addition we have included avail- localities, obtained specimens that show unre- able photographs of live specimens even though corded variation, and received additional speci- most of these are without locality information. mens of two poorly known species, N. bifasciatus The key of Weitzman (1966) has been revised Hoedeman and N. minimus Eigenmann. Examples to accommodate a new generic concept, to admit of a new species from Brazil, N. marilynae, have the new species, to include N. minimus, which been in the senior author's care for nearly 20 years was formerly considered a synonym of N. beck- but were not described as new previously because fordi, and to correct an error. The species names all specimens at hand were juveniles. In 1969 one N. beckfordi and N. digrammus had been inad- of us (Weitzman) found live specimens of this new vertently exchanged in the original key. species in an aquarium shop in the Washington, The methods for taking counts and measure- D. C, metropolitan area. At the same time two ments and the terminology used here for the color males of N. digrammus Fowler were obtained, and pattern of Nannostomus species are the same as life colors of this species are recorded here. All this those outlined by Weitzman (1966). In brief the new material has allowed a reevaluation of the term stripe is restricted to elongate pigmented generic problem within this group of lebiasinids areas that extend horizontally along the sides of as well as a new consideration of species relation- the fish. The primary stripe is the main dark mid- ships. side stripe usually extending from the snout, across the eye, opercle, and body to the caudal-fin base, Stanley H. Weitzman, Division of Fishes, Department of and sometimes onto the caudal fin. The dark Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560. J. Stanley secondary stripe is dorsal to the primary stripe and Cobb, Department of Zoology, University of Rhode Island, lies between the dark pigment of the back and the Kingston, Rhode Island 02881. pale stripe just dorsal to the primary stripe. The 1 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY dark tertiary stripe is the ventralmost and may provided live specimens with locality information extend from the lower jaw, across the ventral part of N. espei and N. minimus. of the operculum, ventral to the base of the pecto- James E. Bohlke, Robert H. Gibbs, Jr., William ral fin, across the ventrolateral part of the belly L. Fink, and David W. Dunham read the manu- just dorsal to the base of the pelvic fins, and to script and offered valuable suggestions. the base of the anal fin. The nocturnal oblique The work was partially supported by Smith- bands are areas of pigment, usually two on each