308 



ONTOGENY AND SYSTEMATICS OF FISHES-AHLSTROM SYMPOSIUM 



in ichthyoplankton surveys. Only B. hathymaster appears to 

 live in relative isolation from other species of Bregmaceros. In 

 the Indo-Pacific, B. ransquamosus (small-size, early matura- 

 tion, low meristics) and B. arabkus (high meristics) possibly 

 were derived from a B. nectabanus stock intermediate in me- 

 ristic characteristics. The basic B. nectabanus stock also may 

 have given rise to B. bathymaster and B. cantori. Detailed study 

 of eastern Atlantic B. cantori-\'\V.e larvae may help to resolve 

 questions about dispersal and evolution of species. 



Bregmaceros Type A is curious. Like B. macclellandi. its lar- 

 vae develop the occipital ray at <2.5 mm (Table 84). Yet, it 

 bears little resemblance to B. macclellandi in other meristic or 

 pigmentation characters. It has the lowest vertebral and median 

 fin ray counts of any Bregmaceros except B. ransquamosus (Ta- 

 ble 83). Larvae of Type A generally occur over the deep shelf 

 and slope, occasionally in oceanic waters, and often co-occur 

 with B. cantori and B. atlanticus (Houde, 1981). 



The status of B. japonicus is unclear although this form may 



be a western Pacific variety or subspecies of B. atlanticus (Be- 

 lyanina, 1974). A recent reexamination of the holotype (Masuda 

 and Ozawa, 1979) indicated that its vertebral and median fin 

 ray counts exceeded or were at the upper extreme of ranges 

 reported for B. atlanticus (Table 83). There is a need for critical 

 examination of B. atlanticus and B. japonicus specimens from 

 the tropical Pacific Ocean. Juveniles and adults that I examined' 

 from the eastern, tropical Pacific appeared to be typical B. at- 

 lanticus but none of the small larvae had typical B. atlanticus 

 pigmentation. A moderately heavily-pigmented larva was pres- 

 ent in tropical Pacific collections that may be an undescribed 

 species. Its status and its possible relationship to the B. atlan- 

 ticus/ B. japonicus systematics problem need to be determined. 



University of Maryland, Center for Environmental and 

 EsTUARiNE Studies, Chesapeake Biological Laboratory, 

 Solomons, Maryland 20688. 



Ophidiiformes: Development and Relationships 

 D. J. Gordon, D. F. Markxe and J. E. Olney 



THE order Ophidiiformes contains 300-400 species occu- 

 pying mostly benthic habitats over a broad range of depth 

 and salinity. These are elongate, tapering fishes with or without 

 a caudal fin. The dorsal and anal fins are long, sometimes con- 

 fluent, without spines and with pterygiophores more numerous 

 than adjacent vertebrae. The pelvic fins, if present, are located 

 far forward and are reduced to one or two rays, sometimes with 

 a small spine. 



Cohen and Nielsen (1978) summarized the present under- 

 standing of the systematics of ophidiiform fishes, presented keys 

 to the genera, and provided a useful framework on which to 

 base a discussion of the order. The presence or absence of vi- 

 viparity defines two suborders, Bythitoidei and Ophidioidei. 

 Bythitoidei contains the live-bearing "brotulids" and is divided 

 into two families, Aphyonidae and Bythitidae. The oviparous 

 Ophidioidei contains Ophidiidae and Carapidae. Ophidiidae 

 includes the cusk-eels (Ophidiinae) and the oviparous "brotu- 

 lids," previously allied with the bythitoids in the family Bro- 

 tulidae. 



Aphyonidae, reviewed by Nielsen (1969), contains 18 species 

 in five genera. These ovoviviparous fishes are benthopelagic and 

 found worldwide. Bythitidae contains over 80 species in 28 

 genera. Most species of this family occur either in shallow trop- 

 ical waters, including coral reefs, or in waters of intermediate 

 depths on the continental shelf and slope. Some deeper-dwelling 

 slope species occur at higher latitudes, a few species inhabit 

 abyssal waters and some are found in freshwater. Carapidae 

 contains about 30 species divided into two subfamilies (Pyra- 

 modontinae, Carapinae) and six genera, all possessing a vexil- 

 lifer larva (Olney and Markle, 1979; Markle and Olney, 1980; 



Markle et al., 1983). Some species are free-living while others 

 are inquilines within the body cavities of invertebrate hosts 

 (Trott, 1 970; Trott, 1981). Ophidiidae, as defined by Cohen and 

 Nielsen (1978), includes oviparous ophidiiform fishes lacking a 

 vexillifer larva and possessing a supramaxillary bone. The fam- 

 ily is divided into four subfamilies: Brotulinae, Brotulotaeni- 

 inae, Neobythitinae and Ophidiinae. Brotulinae contains one 

 genus (Brotula) with at least five species (Cohen and Nielsen, 

 1978). Adult Brotula are benthic and circumtropical on the 

 continental shelf Brotulotaeniinae contains the single genus 

 Brotulotaenia with four midwater, tropical representatives (Co- 

 hen, 1974). Neobythitinae is a morphologically diverse group 

 containing 38 genera and over 135 species with worldwide dis- 

 tribution and a wide depth range, but mostly deep sea. Ophi- 

 diinae consists of about 60 nominal species with several un- 

 described forms (Lea, 1980), mostly in shelf waters. 



Development 



Knowledge of the early life history of ophidiiform fishes varies 

 considerably among major taxa. Larvae of the live-bearing species 

 are infrequently collected and larvae of deep water forms are 

 even rarer. The incomplete state of knowledge of the taxonomy 

 of bythitoid fishes renders identification of most of their larvae 

 tentative. On the other hand, carapid and ophidiine larvae are 

 common to abundant in tropical plankton. Carapid larvae are 

 relatively well known and have proven to be of systematic value 

 (Olney and Markle, 1979; Markle and Olney, 1980). Though 

 the larvae of only a small percentage of the species of ophidiines 

 are known, these larvae provide useful characters for under- 

 standing relationships within the group (Gordon, 1982). 



