ABLE: CYPRINODONTIFORMES 



363 



(Turner, 1937; Scrimshaw, 1945; Turner 1940a; Thibault and 

 Schultz, 1978). 



The eggs of all cyprinodontiforms contain conspicuous oil 

 droplets (Foster. 1967) (Table 97) including the viviparous poe- 

 ciliids such as Gambusia affinis (Kuntz, 1914a). Within the 

 Fundulidae the size and number of oil droplets is extreme; Lu- 

 cania parva has 8-12 large droplets (Fig. 190C) and Fundulus 

 n. sp. from Bermuda has up to approximately 350 with a mean 

 of 181 droplets per egg (Fig. 190F, and Able et al., in prep.). 

 Subspecific variation in the fundulid F. heteroclitus is pro- 

 nounced and population means range from 10 to 180 droplets 

 (Morin and Able, 1983). 



These droplets probably provide nutrition late in embryonic 

 development (Smith, 1957; Lentz and Trinkhaus, 1967; Blaxter, 

 1969a; Temer, 1979). The chemical composition of lipids in 

 the oil droplets has been determined by Bailey (1973). The oil 

 droplets are clumped together at ovulation but disperse after 

 fertilization. Individual oil droplets are retained in the yolk sac 

 after hatching in several Fundulus species, L. parva (see Hardy, 

 1978a), R. marmoratus (McMillan, 1979) and postflexion G. 

 affinis (Ryder. 1885). The eggs of all known oviparous and ovo- 

 viviparous cyprinodontiforms have a small perivitelline space 

 and are spherical (except in Nothobranchius in which the egg is 

 oval, Scheel, 1968). 



The chorion is variable in thickness and surface structure 

 (Table 97). In most of the oviparous and ovoviviparous forms 

 the chorion is multilayered and thick, whereas in many vivipa- 

 rous forms it is considerably reduced (see Flegler, 1977). De- 

 tailed studies of the chorion microstructure are available for the 

 fundulid F. heteroclitus (Kuchnow and Scott, 1977) and the 

 rivulid Cynolebias bellottii (Sterba and Muller, 1962; Muller 

 and Sterba, 1963). The chorion of all oviparous and ovovivipa- 

 rous forms have adornments of some type on the surface. In- 

 stances where they have been reported as lacking (F. heteroclitus, 

 F. parvipinnis. Foster, 1967; F. majalis. Hardy, 1978a) are in- 

 correct. Often the chorion is covered with filaments either uni- 

 formly arranged or clustered together to form tufts (Fig. 190, 

 191; Table 97). The filaments can vary in diameter and density 

 between species (Fig. 190 and 191) and subspecies (Dumont 

 and Brummetl, 1980; Morin and Able, 1983). Differences in 

 these structures in F. heteroclitus appear to be correlated with 

 spawning site preference (Able, 1984). Fundulus majalis has 

 microfilaments on the large filaments and on the chorion surface 

 (Fig. 191 A, B). Some species have other structures ("punctae" 

 of Foster, 1967) which appear as small spherical knobs on the 

 surface of the chorion, occasionally with filaments originating 

 from them (Fig. 190D, E; 19 ID, E). In other species the surface 

 of the chorion may be sculptured (Table 97). Fundulus luciae 

 has numerous circular pits in the chorion surface (Fig. 190D, 

 E). The distribution of chorionic modifications (filaments, mi- 

 crofilaments, pits, knobs) within the Cyprinodontiformes is in- 

 completely known and thus it is difficult to assess their phylo- 

 genetic significance. Several species of fundulids studied possess 

 punctae or knobs (Table 97; Figs. 190, 191) while these are 

 lacking in the cyprinodontids (see Fig. 1 90A, B) thus supporting 

 the separation of these groups by Parent! (1981). 



The presence of chorionic filaments in the Cyprinodonti- 

 formes is a synapomorphy shared with the Atheriniformes and 

 Beloniformes as discussed in this volume and constitutes one 

 of the synapomorphies serving to unite the Atherinomorpha. 

 Further studies of egg morphology in the oviparous forms will 



Table 96. 



Published Descriptions of Cyprinodontiform Early Life 

 History Stages Listed by Family and Genus. 



probably provide useful insights into the phylogeny of this abun- 

 dant and diverse group. 



Embryonic development 



Embryonic development within the Cyprinodontiformes is 

 almost as variable in duration and number of physiological and 

 morphological modifications as in all other fishes combined. 

 The incubation time may be as short as 4-8 days in C. variegatus 

 and Jordanella Jloridae (see Foster, 1967; Hardy, 1978a) to 

 possibly longer than a year in some of the "annual" species. 

 Parent! (1981) considers this annual habit to have developed 

 more than once within the Cyprinodontiformes. This is sup- 



