354 



ONTOGENY AND SYSTEMATICS OF FISHES -AHLSTROM SYMPOSIUM 



only Fodiator acutus (with two subspecies; reaching 195 mm 

 SL); Parexocoetinae with two species of Parexocoetus (reaching 

 140 mm SL); Exocoetinae with three species of Exocoetus 

 (reaching 200 mm SL); and Cypselurinae with four genera— 

 Prognichthys (4 species; reaching 1 90 mm SL), Cypselurus sensu 

 stricto (11 species; reaching 260 mm SL), Cheilopogon (not 

 differentiated from Cypselurus by some authors; 1 8 species; con- 

 tains the largest species of flyingfishes, some reaching 380 mm 

 SL), and Hinmdichthys (8 species; reaching 190 mm SL; in- 

 cludes the more specialized subgenus Danichthys which was 

 recognized as a genus by Bruun and others). All are strictly 

 marine, mostly in tropical and subtropical waters. 



Similarities in the skeletal structure (Parin, 1961) and lateralis 

 system (Parin and Astakhov, 1982) between Exocoetus and the 

 Cypselurinae (Cheilopogon, Cypselurus, Prognichthys, and Hi- 

 rundichthyus) indicate that differentiation of Exocoetus from 

 the main stem took place significantly later than separation of 

 the primitive short-winged flyingfishes (Fodiator and Parexo- 

 coetus). There is particular interest in the interrelationships within 

 the subfamily Cypselurinae. One problem concerns whether 

 Cypselurus should be accepted in the wide sense (Bruun, 1935; 

 Staiger, 1965; Gibbs and Staiger, 1970) or divided into two 

 genera, Cypselurus and Cheilopogon (Parin, 1961). The diag- 

 nostic differences between these two genera are not simple. 

 Therefore, Parin herein presents the following definition: "lower 

 jaw usually a little shorter than the upper; at least some jaw 

 teeth tricuspid; juveniles with a single chin barbel or without 

 barbels" in Cypselurus, and "lower jaw a little longer than upper, 

 teeth mostly unicuspid or with smaller supplementary cusps 

 laterally; juveniles with two barbels which may be fused into a 

 napkin-like appendage" in Cheilopogon. Each genus contains 

 groups of species, several of which were distinguished by Bruun 

 (1935) or Parin (1961) at the level of subgenera. 



The similarities and differences between species groups are 

 most noticeable in the juvenile stages and form the basis of the 

 systematics of the Cypselurinae worked out by Parin (1961). If 

 we consider barbels in flyingfishes to be derived from the pair 

 of cutaneous lappets on the lower jaw of needlefishes, halfbeaks, 

 and primitive flyingfishes, the most generalized state of this 

 character is the presence of two separate barbels. Their deriv- 

 atives are fusion into a single appendage or complete loss. In 

 the speciose genus Cheilopogon, according to the classification 

 of Parin (1961), the juvenile stages of most intrageneric group- 

 ings—the subgenera Procypselurus (composed of the Ch. ni- 

 gricans and Ch. cyanoptenis groups), Maculocoetus, and Abe- 

 ichthys— are characterized by a pair of barbels, sometimes joined 

 at their bases, and presence of an enlarged melanistic dorsal fin 

 ("Parexocoetus stage"). In juveniles of the subgenus Cheilopo- 



gon. the dorsal fin is greatly enlarged, but the barbels are fused 

 into a fringed appendage. In the subgenus Ptemchthys, paired 

 barbels remain but the " Pare.xocoetus stage" is lost (present only 

 in Ch. longibarbits, which, apparently should be removed from 

 this subgenus). The subgenus Paracypselurus is somewhat in- 

 termediate between Cheilopogon and Cypselurus. Juveniles have 

 paired barbels and an enlarged dorsal fin, but adults are closer 

 to Cypselurus \n structure ofthejaw and other characters (except 

 absence of tricuspid teeth). 



Summary 



There is a considerable amount of information available on 

 the early life stages of beloniform fishes. Specialized structures 

 such as egg filaments, barbels, beaks, and melanistic dorsal fin 

 lobes have systematic value. It is pleisiomorphous for the eggs 

 of beloniform fishes to have chorionic filaments (Rosen and 

 Parenti, 1981). One or more loss events presumably gave rise 

 to the apomorphous condition, an absence of chorionic fila- 

 ments, seen in the dwarf sauries (Cololabis adocetus and Scom- 

 heresox simidans) and in the flyingfishes of the genus Exocoetus. 

 The development of a beak during some life stage is a derived 

 feature that occurs in all belonids, scomberesocids (except C 

 adocetus) and hemiramphids, and the two most primitive ex- 

 ocoetid genera (Fodiator and Pare.xocoetus). It is never found 

 in the adrianichthyids. Presence of a beak is a synapomorphy 

 for the Exocoetoidei and supports Rosen and Parenti's (1981) 

 division of the Beloniformes into two suborders, the Adrianich- 

 thyoidei (no beak) and the Exocoetoidei (beak). A second char- 

 acter that supports this is relative length of the gut at hatching, 

 40-50% standard length in Adrianichthyoidei and approxi- 

 mately 66% in the Exocoetoidei. The superfamily Scombere- 

 socoidea differs from the Exocoetoidea in having a premaxillary 

 lateral line canal and in having the upper jaw at least slightly 

 elongate. 



(B.B.C.) National Marine Fisheries Service Systematics 

 Laboratory, National Mliseum of Natural History, 

 Washington, District of Columbia 20560; (G.E.M.) 

 Section of Ichthyology. Los Angeles County Museiim 

 OF Natural History, 900 E.xposition Boulevard, Los 

 Angeles, California 90007; (N.V.P.) P.P. Shirshov 

 Institute of Oceanology, Academy of Sciences of the 

 U.S.S.R., Krasikova Street 22, Moscow 1 1 72 1 8, U.S.S.R.; 

 (S.M.) Research Division, Fisheries Agency, Ministry 

 OF Agriculture, Forestry and Fisheries, Government 

 OF Japan, 2-1, 1-Chome, Kasumigasekj, Chiyoda-Ku, 

 Tokyo, Japan. 



