366 



ONTOGENY AND SYSTEMATICS OF FISHES -AHLSTROM SYMPOSIUM 



Fig. 191. Scanning electron micrographs of the chorion surface of the fundulids F. majalis (A, B), Fundulus n. sp. from Bermuda (C), the 

 rivulid Rinilus mannoratus (D, E) and the profundulid Profundulus punctalus (F). 



ported by an apparent difference in the manner in which hatch- 

 ing is delayed. Fundulus confluentus can hatch after three months 

 of "latency" or postponement of hatching (Harrington, 1959; 

 Harrington and Haeger, 1958) while the embryos continue to 

 grow and utilize yolk reserves. Delayed hatching is probably 

 typical for many North American fundulids, as seen in F. het- 

 eroclitus (Taylor et al., 1977) and Adinia xenica (Koenig and 

 Livingston, 1976). The incubation period is known to be influ- 

 enced by temperature (see Gabriel, 1944) and dissolved oxygen 

 (DiMichele and Taylor, 1980). During diapause, which occurs 

 in the annual killifishes (Wourms, 1972a, b, c) hatching may be 

 delayed for up to six months in nature and possibly longer than 

 a year under extreme conditions. During this time growth does 

 not occur, cardiac activity ceases and the yolk is not depleted. 

 The length of the incubation period may be controlled by tem- 

 perature, photoperiod, desiccation and oxygen tension cues (see 

 Matias, 1982). 



The embryonic development of several aplocheilids (Aploch- 

 eilus), a rivulid {Rivulus) and two fundulids (Adinia and F. 



heteroclitus) has been described in detail (Table 96). Some 

 authors have placed special systematic significance on the pat- 

 tern of vitelline circulation of the embryo in cyprinodonti forms 

 (Foster, 1967; Hubbs and Bumside, 1972) and other atherino- 

 morphs (White et al., this volume). The viviparous poeciliids, 

 anablepids, jenynsiids (placed in the Anablepidae by Parenti, 

 1981) and goodeids have a variety of modifications for receiving 

 nourishment during development (reviewed by Wourms, 1981). 

 The phylogenetic significance of independent development of 

 viviparity in several cyprinodontiform lineages is discussed in 

 detail by Parenti (1981). 



Larvae 



The larvae of oviparous cyprinodontiforms are incompletely 

 known (Table 96) despite the fact that many of them are avidly 

 bred by aquarium hobbyists. All of those known lack the preanal 

 finfold characteristic of the beloniforms (except exocoetids) 

 (Collette et al., this volume) and have a longer preanal length 

 than the atheriniforms (White et al.. this volume). In all cy- 



