Lophiiformes: Development and Relationships 



T. W. PlETSCH 



THE order Lophiiformes is an assemblage of 18 families, 63 

 genera, and approximately 282 living species of marine 

 teleosts, the monophyletic origin of which seems certain based 

 on the following synapomorphic features: (1) Spinous dorsal fin 

 primitively of six spines, the anteriormost three of which are 

 cephalic in position and modified to serve as a luring apparatus 

 [involving numerous associated specializations, e.g., a medial 

 depression of the anterior portion of the cranium, loss of the 

 nasal bones (nasal of Rosen and Patterson, 1969 = lateral eth- 

 moid) and supraoccipital lateral-line commissure, and modifi- 

 cations of associated musculature and innervation]; (2) Epiotics 

 separated from parietals and meeting on the midline posterior 

 to the supraoccipital; (3) Gill opening restricted to a small, elon- 

 gate tubelike opening situated immediately dorsal to, posterior 

 to, or ventral to (rarely partly anterior to) pectoral-fin base; (4) 

 Second ural centrum fused with the first ural and first preural 

 centra to form a single hypural plate (sometimes deeply notched 

 posteriorly) that emanates from a single, complex half-centrum 

 (Rosen and Patterson, 1969:441, text figs. 4E, 60); (5) Pectoral 

 radials narrow and elongate, the ventral-most radial consider- 

 ably expanded distally; and (6) Eggs spawned in a double, scroll- 

 shaped mucous sheath (Rasquin, 1958). 



Within the order there are currently recognized three subor- 

 ders: the Lophioidei, containing a single family and 25 species 

 of relatively shallow- water, dorso-ventrally flattened forms (Ca- 

 ruso, 1981, 1983; Caruso and Bullis, 1976); the Antennarioidei, 

 with six families and approximately 121 species, nearly all lat- 

 erally-compressed, shallow-water, benthic forms (Bradbury, 

 1967; Pietsch, 1981, 1984; Pietsch and Grobecker, in press); 

 and the Ceratioidei, containing about 136, typically globose, 

 meso- and bathypelagic species (Bertelsen, 1951; see also Ber- 

 telsen, this volume). 



Development 



Little is known about the early life stages of lophiiform fishes, 

 unequal information being available for only the Lophiidae, 

 Antennariidae and most ceratioid families. Eggs are well-known 

 in lophiids (Fulton, 1898; Bowman, 1920; Bigelow and Welsh, 

 1925) and antennariids(Mosher, 1954; Rasquin, 1958) but un- 

 known in all other lophiiforms. Larvae are adequately described 

 in lophiids (Bowman, 1920; Martin and Drewry, 1978), anten- 

 nariids(Mosher, 1954; Rasquin, 1958) and most ceratioids (Ber- 

 telsen, 1951), but remain undescribed in chaunacids and ogco- 

 cephalids despite some available material. 



Probably the most striking characteristic of early ontogeny in 

 lophiiforms is the fact that eggs are spawned embedded in a 

 continuous, ribbon-like sheath of gelatinous mucous, often re- 

 ferred to as an "egg-raft" or "veil" (with one known exception, 

 see Pietsch and Grobecker, 1980). Within this mucous veil are 

 found thousands of roughly-hexagonal, liquid-filled chambers 

 arranged in one to several irregular layers, each chamber con- 

 taining from one to three eggs (see Rasquin, 1958 for further 

 details and figures of the structure of egg rafts). Development 

 is fairly direct, with the larvae in all known groups gradually 

 acquiring adult characters over a size range of approximately 5 



mm total length (TL) in antennariids to 65 or 70 mm TL in 

 lophiids. Specialized ontogenetic stages are absent except for the 

 peculiar "scutatus" prejuvenile present in the ontogeny o{ An- 

 lennarius radiosus (see below). 



Lophiidae 

 Of the 25 species and four genera of the Lophiidae (Caruso, 

 198 1), early life stages have been described for only three species, 

 all of the genus Lophius: L. americamts (Martin and Drewry, 

 1978, and numerous references cited therein), L. piscatohus 

 (Tuning, 1923) and L. /'(/a'e^a5M(Padoa, 1 956e). Of these, early 

 ontogeny is best documented in L. americanus. a spring or 

 summer spawner, whose egg rafts measure 0. 1 5-1 .5 m wide and 

 6-12 m long. Living eggs are slightly oval, their major axis 

 measuring 1.61-1.94 mm. The outer shell appears smooth and 

 transparent, the yolk homogeneous and amber in coloration. 

 The perivitelline space is narrow. A single, copper, orange or 

 pinkish-colored oil globule is present, having a diameter of ap- 

 proximately 0.40-0.45 mm. Yolk-sac larvae measure 2.5-4.9 

 mm TL. The larvae, ranging in size from 6.5 to approximately 

 10.5 mm TL, are prominently pigmented, with early-forming 

 dorsal rays and pectoral and pelvic fins (Fig. 164A). Relative to 

 antennariid larvae, the head is small, somewhat less than 30% 

 of standard length. The gut is unusually short. The dorsal and 

 pelvic rays are unusually elongate. The soft-dorsal and anal fins 

 are last to form. The pectoral fin is typically large and fan- 

 shaped. Fin ray counts are complete by approximately 12 mm 

 TL. Transformation to the prejuvenile stage takes place at a size 

 somewhat greater than approximately 12 mm TL; the juvenile 

 stage is not reached until at least 65 mm TL. In well preserved 

 specimens of some species (i.e., Lophiodes spilurus; SIO 59-324, 

 65.5 mm TL) the epidermal layer of the head and body is greatly 

 distended by transparent, gelatinous connective tissue, giving 

 the larvae an inflated or balloon-like appearance (as described 

 for ceratioid larvae by Bertelsen, 1951:12; see also Bertelsen, 

 this volume). (Largely taken from Martin and Drewry, 1978: 

 359-366, where the reader will find a full series of figures and 

 more detailed description of early ontogeny.) 



Although the significance of variation in larval pigmentation 

 in lophiids is largely unknown, larvae of the American species, 

 Lophius americanus Valenciennes, are more easily distin- 

 guished from those of the European L. piscatorius Linnaeus than 

 are the adults, using characteristic differences in pigmentation 

 (Taning, 1923; Martin and Drewry, 1978). Tuning (1923), after 

 studying early developmental stages, considered the two species 

 to be distinct at a time when many authors regarded them as 

 synonyms (Martin and Drewry, 1978). 



Meristic characters that typify early life stages of lophiids are 

 compared with those of other lophiiforms in Table 88. 



Antennariidae 



The family Antennariidae consists of 41 species distributed 

 among 1 2 genera (a modification of Schultz, 1957; Pietsch, 1981, 

 1 984; Pietsch and Grobecker, in press). Of these, early life stages 



320 



