AMERICAN MUSEUM Novltates PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY CENTRAL PARK WEST AT 79TH STREET, NEW YORK, N.Y. 10024 Number 3195, 17 pp., 6 figures, 1 table May 16, 1997 Egg Surface Structure and Larval Cement Glands in Nandid and Badid Fishes with Remarks on Phylogeny and Biogeography* RALF BRITZ' ABSTRACT Egg surface structure and larval morphology of procedure. The genus Afronandus is tentatively the Nandidae and Badidae were studied with assigned to this monophyletic group because it SEM, and cement organs of larval Nandus and shares with the other three African-South Amer- Badis were histochemically stained using the PAS ican Nandidae the character of adhesive filaments technique. The study is supplemented with data at the vegetal egg pole. Comparison of egg and on reproductive behavior. The Asian Nandidae larval structure between the Nandidae and Badi- differ from the African-South American Nandi- dae revealed no characters indicating a close re- dae in important features of reproductive behavior lationship of the two families. as well as egg and larval structure. No synapo- Lundberg's (1993) hypothesis, which explains morphy for the family Nandidae could be identi- the distribution of the African-South American fied. The genera Polycentropsis, Polycentrus, and Nandidae by dispersal through seawater, is reject- Monocirrhus, however, form a monophyletic ed on the basis of the ecological preferences of group on the basis of the following synapomor- these Nandidae. The age of origin of African- phies: eggs with a unique surface pattern of nar- South American Nandidae is hypothesized to date row ridges running radially from the micropyle; back at least to the late Cretaceous, that is, before larvae with a multicellular cement gland on top the separation of Africa and South America. of the head; and adults with a unique spawning * This paper is dedicated to the memory of the influential zoologist Hans M. Peters who died December 13, 1996, at the age of 89. ' Postdoctoral Fellow, Department of Herpetology and Ichthyology, American Museum of Natural History. Present address: Lehrstuhl fur Spezielle Zoologie, Universitat Tubingen, Auf der Morgenstelle 28, 72076 Tubingen, Germany. Copyright X American Museum of Natural History 1997 ISSN 0003-0082 / Price $2.40 2 AMERICAN MUSEUM NOVITATES NO. 3195 INTRODUCTION Nandidae, or leaffishes, occur in fresh wa- mented by data obtained from ovarian eggs ters of Southeast Asia, West Africa, and of the poorly known West African species South America (Berra, 1981; Nelson, 1994), Afronandus sheljuhzkoi. After evaluating the a disjunct distribution that has been noted by phylogenetic significance of these new data, a number of ichthyologists and zoogeogra- the hypothesis recently proposed by Lund- phers (see Lundberg, 1993 for a review). In berg (1993) to explain the current distribu- the past, seven genera, Nandus, Afronandus, tion of the family Nandidae and its sub- Polycentropsis, Polycentrus, Monocirrhus, groups was examined. Badis, and Pristolepis, have been arranged in various combinations with different numbers ACKNOWLEDGMENTS of families (Gunther, 1861; Boulenger, 1904; Jordan, 1923; Weber and De Beaufort, 1936; I am deeply indebted to R. Rucks (Kiel) Berg, 1958; Greenwood et al., 1966; Liem, and R. Donoso-Buchner (Dorsten) for pro- 1970; Lauder and Liem, 1983; Nelson, viding eggs and larvae of Polycentropsis, 1994). They are usually classified as mem- Monocirrhus, and Badis and for sharing with bers of the Percoidei (Johnson, 1984; Nelson, me their profound knowledge of nandid be- 1994), although sometimes a closer relation- havior. I am grateful to the individuals at the ship to the Anabantoidei (labyrinth fishes) or Lehrstuhl fur Spezielle Zoologie, Universitat the Channidae (snakeheads) has been postu- Tiubingen, especially W. Maier for the op- lated (Gosline, 1968, 1971; Nelson, 1969; portunity to maintain specimens of N. nan- Rosen and Patterson, 1990). Barlow et al. dus and B. badis at his institute, H. Schop- (1968) compared breeding behavior, egg and pmann for his expert skills with SEM, and larval morphology, and osteology of Badis M. Hohloch and M. Meinert for a variety of and Polycentrus and found striking differ- technical advice and assistance. G. Teugels, ences between the two genera. As a conse- Musee Royale de L'Afrique Centrale quence, they removed Badis from the Nan- (MRAC; Tervuren), kindly lent a specimen monotypic family, of Afronandus shelhjuhzkoi for SEM of its didae and erected a new eggs. At the American Museum of Natural Badidae. Subsequently, Pristolepis also was P. to the History (New York), the help of Fong- considered to be related only remotely Melville with SEM was greatly appreciated. Nandidae (Liem, 1970; Liem and Green- The present study was supported by a grant wood, 1981). Liem (1970) restricted the fam- of the Landesgraduiertenforderung Baden- ily Nandidae to five genera, Nandus, Afron- Wurttemberg at the Lehrstuhl fur Spezielle andus, Polycentropsis, Polycentrus, and Zoologie and subsequently by a Kalbfleisch Monocirrhus, and provided an osteological Postdoctoral Fellowship at the Department of definition of the group. Nevertheless, he ad- Herpetology and Ichthyology of the Ameri- mitted that "no single osteological feature can Museum of Natural History. distinguishes the family from other per- The manuscript was read and greatly im- coids" (op. cit. p. 82). The monophyly of the proved by the comments of M. Toledo-Piza, Nandidae is still questionable and its phylo- G. Nelson, and J. Atz and by the reviews of genetic inter- and intrarelationships remain S. 0. Kullander and K. F Liem. unresolved (Lundberg, 1993). Aquarium breeding of three geographical- MATERIALS AND METHODS ly separated Nandidae-the Southeast Asian Nandus nandus, West African Polycentropsis Freshly spawned, fertilized eggs and lar- abbreviata, and South American Monocir- vae of N. nandus, P. abbreviata, M. poly- rhus polyacanthus-as well as the Southeast acanthus, and B. badis were prepared for Asian Badis badis provided the opportunity SEM using the procedure described in Britz to investigate whether egg and larval char- et al. (1995). They were observed and pho- acters reported for Polycentrus by Barlow et tographed with a Cambridge Stereoscan 250 al. (1968) are actually representative of the Mk2. Nandidae. These results have been supple- Ovarian eggs of A. sheljuhzkoi were ob- 1997 BRITZ: NANDID AND BADID FISHES 3 tained from a preserved female specimen tained about 70 ripe eggs with a diameter of (MRAC 73-05-P-4669-4674). After remov- 1.1-1.3 mm. The size of spawned, fertilized ing maternal tissue by use of fine forceps, eggs may be slightly larger due to formation eggs were critical-point dried in a Balzers of the perivitelline space (Laale, 1980). The CPD 030, coated with 150 A gold-palladium, vegetal egg pole bears a tuft of filaments that and observed and photographed using a originates from a circular area on the zona Zeiss DSM 950. radiata (fig. IE, F) and supposedly serves to To confirm the position and shape of ce- attach the egg to the substrate. The micropyle ment glands or individual cement cells, lar- is situated on the opposite pole (fig. IG) and vae of N. nandus (2.5 days postspawning) has a diameter of almost 4 ,um. The zona and B. badis (-3 days postspawning) were radiata near the micropyle does not show any studied histochemically. The larvae were striking surface structure (fig. 1H) apart from stained in toto for mucopolysaccharides in the numerous canal openings typical of many accordance with the PAS (= periodic acid teleost eggs (Stehr and Hawkes, 1983; Riehl, Schiff reaction) technique of Peters and 1991). Berns (1982) and then photographed with a POLYCENTROPSIS ABBREVIATA: The male of Zeiss Tessovar. this other West African nandid usually builds a nestlike structure of air bubbles under RESULTS leaves that are floating at the water surface; EGG STRUCTURE IN THE NANDIDAE eggs are attached to the underside of these leaves (Rucks, 1992). The male guards the NANDUS NANDUS: Two Southeast Asian spe- clutch, which may consist of 300-350 eggs cies of the genus Nandus, for which infor- (Scheel, 1964b; Rucks, 1992). Eggs measure mation is available, spawn several thousand 1.3-1.4 mm in diameter. SEM reveals that small, translucent eggs that adhere to plants their vegetal pole attaches to the leaf with the and other substrates and show no parental aid of a stalk of radially arranged fiber bun- care (for N. nandus: Parameshwaran et al., dles (fig. 2A). Each bundle originates from 1971; personal obs.; for N. nebulosus: Rucks, the zona radiata of the egg (fig. 2B) and ends 1973, 1996). Respective data for the newly at a distance of -0.5 cm (fig. 2A). Bundles described third species in the genus, Nandus are about 10 ,um wide and consist of many oxyrhynchus (Ng et al., 1996), are lacking. smaller individual fibers that had a width of Spawned eggs of N. nandus measure 0.7-0.8 0.2-0.3 ,um each (fig. 2B). The zona radiata mm in diameter. SEM demonstrated that the shows a distinct honeycomblike surface pat- animal pole of the egg adheres to the sub- tern where the fibers originate (fig. 2B). The strate (fig. IA); to observe the micropyle, the animal pole bears a considerable number of egg had to be removed from the substrate radial ridges which run radially from the oval (fig. iB). A circular area around the micro- micropylar pit situated in a craterlike eleva- pyle bears a dense carpet of short filaments tion (fig. 2C). The micropyle also has a (fig. IC, D) that appear to be primarily re- slightly oval shape, 4 ,um long and 2 ,um sponsible for the attachment of the egg to the wide (fig. 2D). substrate. The micropyle is situated in the MONOCIRRHUS POLYACANTHus: The South middle of this area and has a diameter of -2 American nandid M.