Geographic Distribution of the San Juan Ichthyofauna of Central America with Remarks on Its Origin and Ecology
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University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Investigations of the Ichthyofauna of Nicaraguan Lakes Papers in the Biological Sciences 1976 Geographic Distribution of the San Juan Ichthyofauna of Central America with Remarks on its Origin and Ecology William A. Bussing Universidad de Costa Rica Follow this and additional works at: https://digitalcommons.unl.edu/ichthynicar Part of the Aquaculture and Fisheries Commons Bussing, William A., "Geographic Distribution of the San Juan Ichthyofauna of Central America with Remarks on its Origin and Ecology" (1976). Investigations of the Ichthyofauna of Nicaraguan Lakes. 11. https://digitalcommons.unl.edu/ichthynicar/11 This Article is brought to you for free and open access by the Papers in the Biological Sciences at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Investigations of the Ichthyofauna of Nicaraguan Lakes by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Published in INVESTIGATIONS OF THE ICHTHYOFAUNA OF NICARAGUAN LAKES, ed. Thomas B. Thorson (University of Nebraska-Lincoln, 1976). Copyright © 1976 School of Life Sciences, University of Nebraska-Lincoln. Geographic Distribution of the San Juan Ichthyofauna of Central America with Remarks on its Origin and Ecology WILLIAM A. BUSSING INTRODUCTION Recent collections on the Atlantic versant of Honduras and Nicaragua reveal a depauperate ichthyofauna with lit The scientific study of fishes of the Great Lakes of tle endemism. The San Juan Assemblage clearly extends to Nicaragua began in 1864 with the description by Gunther northern Nicaragua before merging with a marginal of Heros labiatus (=Cichlasoma labiatum) from Lake Man Usumacinta fauna. Collections from Panama and Costa agua. Subsequently, Gunther reported on several other Rica also reveal that the southern limit of the San Juan species collected in the Great Lakes by Captain M. Dow. J. Province lies southward in Panama. Astorqui (1967) reviewed the sparse ichthyological litera Provisional province limits were placed where considera ture dealing with Nicaraguan fishes and pointed out the ble faunal changes occur in the assemblages of adjacent paucity of recent studies. Since then Villa (1971) has pro watersheds. Species were then assigned to one or more pro duced a provisional list of the freshwater and brackish vinces on the basis of their distribution, and the totals com water fishes of Nicaragua and Astorqui (1972) has analyzed piled by drainage basin. Interpolation was applied in these the ichthyofauna of the Great Lakes Basin. Riedel (1972) charts where known distributions were discontinuous. Final discussed the geological history of the Great Lakes in rela placement of province limits was then made and all species tion to the composition and evolution of its fish fauna. were reassigned to provinces on the basis of this last judg The present paper analyzes the existing distribution and ment. ecology of the lower Central American ichthyofauna, in In addition to the above empirical method, a computer light of paleogeologic knowledge, in order to determine the analysis was applied to the same distributional data of the derivation of historical faunal elements, the barriers re principal Atlantic drainages between eastern Guatemala sponsible for subdivision of these ancestral ichthyofaunas, and eastern Panama (Table 1 and Fig. 1). Drs. Jay M. Sav and the subsequent dispersal which has resulted in secon age and Ian R. Straughan of the Allan Hancock Founda dary distributions of the descendent species in the San Juan tion, University of Southern California, applied a Poly the tic Fish Province. For the purposes of this analysis, only Aglomerative Classification using the similarities indexes of freshwater fishes (i.e., species of non-marine affinity) are Czekanowski or Jaccard and the flexible sorting strategy, utilized. normal (site site) analysis and inverse (species species) analysis. Results were determined from a dendrogram that FISH PROVINCES OF CENTRAL AMERICA shows the degree of similarity between these groups of The present state of distributional and systematic knowl drainage basins. The results confirm the significance of the edge of the Middle American ichthyofauna now permits faunal boundaries recognized by the intuitive approach, major fish provinces to be outlined, although a revision of but reveal that the Usumacinta-SanJuan boundary was in one major taxon (Rhamdia) may modify the number of correctly placed. The faunal boundaries are as follows in species components somewhat. descending order of significance: 1) a major discontinuity In preparing an analysis of faunal provinces, I have re between the San Juan and Isthmian Provinces, 2) a very lied heavily on Miller's (1966) data for fish distribution in significant discontinuity between the San Juan and northern Middle America and for his tentative delimitation Usumacinta Provinces, 3) a significant discontinuity be of the northern boundaries of the Usumacinta and tween the Rio Motagua and Ulua basins, 4) significant dis Chiapas-Nicaraguan Provinces. The Panamanian drainage continuities between the Rio Cocle Norte and Chagres ba systems delineated by Loftin (1965) and his distribuJional sins and Chagres and San Bias watersheds of the Isthmian data, modified by subsequent study of some of the material, Province. On the basis of these results, Table 1 was pre were incorporated in the analysis. A geographic analysis of pared to show for each drainage the total number of species Honduran fishes by Martin (1972), based on extensive col and the number of these which also occur in the other lections from both Atlantic and Pacific versants, was crucial drainages (i.e., the degree of affinity between the species of in the study. Other critical collections from previously un each basin and each of the provinces). For example, there collected localities in Nicaragua were generously donated are 46 freshwater species known from the San Juan basin; by Jaime Villa and supplemented by my own collections all by definition are members of the San Juan Province; 20 from central and southern Nicaragua. Collections made in of these also occur in the Usumacinta Province and 7 in the Central America since 1961 to the present, by numerous Isthmian Province (Table 1). collectors, provided knowledge of Costa Rican fish distribu Usumacinta Province.-Miller (1966) delimited the pro tion (Bussing, 1967) and establish limited additions to the vince and discussed its ichthyofauna. In the present ar ichthyofauna of other Central American republics. rangement, the province is extended to include the entire 157 BUSSING TABLE 1. Distribution of freshwater fishes by Atlantic drainages (Lopez, 1972). Many Isthmian freshwater species drop out from southern Guatemala to eastern Panama. The total number of in this region and widespread Central American species species per drainage is given first, followed by the number of aside, only one Isthmian species reaches the Tarcoles species of each drainage represented in each of the other Central drainage to the north. No Chiapas-Nicaraguan species American Fish Provinces. The abbreviations to the left of each drainage refer to the map symbols in Figure 1. reach the Pirris drainage except ubiquitous forms which extend along the entire Pacific slope. A more detailed Drainage Total Usumacinta Sanjuan Isthmian species treatment of Costa Rican zoogeography will be presented elsewhere. PO Polochic 30 30 11 5 Between the northern limits mentioned and the southern MO Motagua 31 31 14 5 border of Panama, 97 species representing 51 genera and UL Ulua 26 26 17 6 c:'" 12 families of freshwater fishes occur in the Isthmian Pro 'u LA La Ceiba 23 23 15 6 '"E vince. ::> AG Aguan 23 23 18 6 ;5 PL Paulaya 19 19 16 6 Chiapas-Nicaraguan Province.-North of the Punta Mala PT Patuca 21 21 18 6 promontory, the narrow Pacific coastal plain receives much CO Coco 23 23 20 6 less rainfall than southern Costa Rica or the Atlantic low lands. I have not analyzed this faunal assemblage in detail, PR Prinzapolka 24 20 24 6 ES Escondido 24 19 24 6 but some observations are pertinent to an understanding of SJ Sanjuan 46 20 46 7 the San Juan ichthyofauna. This area, as delimited by Mil "'" CR Chirrip6 30 17 30 7 ler (1966) and modified by the present study, certainly qual -," PA Parismina 27 16 27 7 ifies as a fish province. Depauperate as it is, endemism is MA Matina 24 15 24 7 marked and several species are autochthonous. Forty-five rJ'J"'" 51 Sixaola 18 12 18 9 species representing 18 genera and 9 families of freshwater CH Changuinola 18 11 18 10 fishes occur in the region. It must be pointed out however, LC L. Chiriqui 19 10 19 11 that at least 14 of the 45 known species are primarily Atlan GM G. Mosquitos 18* tic forms that have gained access to the Pacific slope through several dispersal routes in the southern part of the " CN Code Norte 17 6 11 17 ·s'" CG Chagres 33 6 11 33 province. Few of these species are widely distributed on the ~ SB San BIas 25 4 9 25 Pacific versant, which suggests recent arrival, competition with better adapted species, and/or difficulty in surviving in -By interpolation a region subject to xeric climate. From south to north, the following areas are affected by Atlantic versant of Honduras and northern Nicaragua to Atlantic faunal intrusion: between the Rio Coco and Prinzapolka drainages (Fig. 1). 1) The Rio Bebedero and Rio Tempisque drainages of On the basis of this delimitation, 130 species representing Guanacaste Province, Costa Rica contain two widespread 34 genera and 10 families of freshwater fishes occur in the species of Atlantic origin, Cichlasoma dovii and C. longimanus, province. and four species of restricted distribution, Cichlasoma alfari, Clearly a subprovince is indicated between the Rio Herotilapia multispinosa, Alfaro cultratus and Rivulus isthmen Motagua and Rio Coco drainages, but this depauperate re sis. The headwaters of the Rio Tempisque pass within 200 gion harbors no distinctive major fauna nor the endemic meters of Atlantic tributaries of the Rio Sapo a at 400 meters forms which would permit a major province rank.