618 



ONTOGENY AND SYSTEMATICS OF FISHES-AHLSTROM SYMPOSIUM 



The numbers at the nodes indicate characters that are discussed 

 by Collette and Russo (in press). 



Scomberomorus differs from Acanthocybium at character 17 

 and from all other scombrids in possessing a spatulate vomer 

 that projects anteriorly well beyond the neurocranium. Scom- 

 beromorus differs from both Acanthocybium and Grammator- 

 cynus in 12 osteological characters. In three more characters, 

 Scomberomorus differs from both genera but is closer to Acan- 

 thocybium. Scomberomorus and Acanthocybium share 17 os- 

 teological synapomorphies at character 18 but differ from 

 Grammatorcynus. There are six species groups within Scom- 

 beromorus: sinensis, commerson, munroi. semifasciatus. gut- 

 tatus. and regalis (Fig. 325; Collette and Russo, in press). 



The young stages of scombrids are difficult to identify to genus 

 and particularly to the species level (Richards and Potthoff, 

 1974). Young stages are, for the most part, easily identified to 

 family, but the eggs are unknown except for a few species. To 

 give some indication of the amount of work already directed to 

 these problems, a recent bibliography of young scombrids cov- 

 ering the years 1880-1970 listed 170 papers dealing with iden- 

 tification of eggs, larvae, and juveniles (Richards and Klawe, 

 1972). Where no specific references are indicated, information 

 is from papers listed by Richards and KJawe (1972) or Fritzsche 

 (1978). 



Development 



Scombrid eggs are very difficult to identify because they re- 

 semble the vast majority of perciform eggs characterized by 0.8- 

 1 .9 mm in diameter, smooth shell, usually a single oil globule 

 (several in Sarda), narrow perivitelline space, homogenous yolk 

 and a variety of distribution patterns of pigment cells including 

 melanophores and other pigments, usually yellow, white or green. 

 The latter three colors are lost upon preservation and are only 

 useful for identifying living eggs. Because of the great interest 

 in rearing scombrids from eggs, several papers have appeared 

 which describe living eggs, but not enough species have been 

 described to shed light on relationships. The following works 

 should be consulted: Harada et al. (1971); Mori et al. (1971); 

 Richards and KJawe (1972); Harada, Muruta and Miyashita 

 (1973); Harada, Muruta and Furutani (1973); Yasutake et al. 

 (1973); Harada et al. (1974); Ueyanagi et al. (1974); and Mayo 

 (1973). 



Most larvae can be identified using a combination of char- 

 acters, principally number of myomeres, body shape, head spi- 

 nation, and distribution of melanophores. Larvae are unknown 

 for only three genera— Gasterochisma. Orcynopsis and Cybio- 

 sarda. The present state of knowledge of larval scombrids is 

 shown in Table 158. Morphological characters common to lar- 

 vae of this family are: (1) large head, large mouth opening and 

 large eye; (2) development of head spination; (3) posterior mi- 

 gration of anus (anus located in anterior region of body in early 

 larval stage; it migrates posteriorly toward anal fin during de- 

 velopment). 



The following accounts follow the order of presentation in 

 Table 158. 



Scomber and Rastrelliger (Fig. 326). — These two genera are 

 thought to be the most primitive and lack some of the larval 

 specialization seen in the other genera (Rastrelliger is not illus- 

 trated). The first dorsal fin forms after the second dorsal whereas 

 in other genera the first dorsal develops before the second dorsal. 



The head is not large (less than 'A SL) in comparison with other 

 genera. The dorsal profile of the head is gently arched from 

 above the eye to the tip of the snout which is rounded. Head 

 spination is not developed. The typical pigmentation is the pres- 

 ence of melanophores on the mid- ventral side of the trunk and 

 tail in both genera. Myomeres number 3 1 . The species of Scom- 

 ber can be separated except it is difficult to distinguish S. ja- 

 ponicus from 5. australasicus. Head proportion and pre-anal 

 length may be useful as diagnostic characters. 



Grammatorcynus (Fig. 326). — Grammatorcynus bilineatus lar- 

 vae resemble Scomber and Rastrelliger in dorsal profile of head 

 but have a pointed snout. Head spination is not developed but 

 preopercular spines are present. Typical pigmentation is the 

 presence of a lateral pigmented blotch above the anal fin and 

 the development of saddle-shaped pigment blotches on the body 

 and a pigment patch on the caudal fin base in larger larvae. Also 

 characteristic are two lateral lines which are discernible at 57 

 mm SL in juveniles. Myomeres number 31. The larvae were 

 recently re-described by Nishikawa (1979), but larvae of the 

 second species, G. bicarinatus. recently recognized by Collette 

 (1983) are unknown. 



Scomberomorus (Fig. 327).— This speciose genus is character- 

 ized by having a supraoccipital protuberance (Euthynnus has a 

 slightly discemable protuberance). The head is large with an 

 elongate snout and large mouth. Preopercular spines are well 

 developed, and in at least one species, S. cavalla, are the longest 

 in the family. A spiny supraorbital crest is well developed. Me- 

 lanophores appear on the mid-dorsal and mid-ventral side of 

 the trunk and tail. Adequate descriptions have been published 

 for S. cavalla and S. maculatus and recently (Jenkins et al., 

 1984) for 5. commerson. S. queenslandicus and 5. semifascia- 

 tus. 



Acanthocybium (Fig. 327).— This single species has been well 

 described and is very easy to recognize (Wollam, 1969; Mat- 

 sumoto, 1968). It is characterized by a large number of myo- 

 meres (62-64), elongate gut, elongate snout, and melanophores 

 on the bases of the second dorsal and anal fins (on larvae >6 

 mm SL). It is the only species which does not exhibit posterior 

 migration of the anus. 



Sarda (Fig. 327).— The snout is moderately elongate and the 

 head spination, consisting of supraorbital crests, preopercular 

 spines and pterotic spines, are well developed. Dentition on 

 both jaws is well-developed. Melanophores occurring on the 

 ventral midline appear to migrate dorsally along myosepta with 

 growth in a posterior to anterior direction. In postflexion larvae 

 the pelvic and first dorsal fin are heavily pigmented. Good, 

 thorough descriptions are lacking for all of the species. 



Gymnosarda (Fig. 327).— The larvae of this monotypic genus 

 are unique in the remarkable development of the head, espe- 

 cially elongation of the snout, wide mouth with fang-like den- 

 tition, and spinous preopercles, supraorbital crests, and pterotic 

 spines. The extremes of the body proportions are: ca. 60% for 

 head in SL, ca. 60% for snout in head, and ca. 85% for upper 

 jaw in head. Melanophores are absent from the tail region and 

 the branchiostegal rays are heavily pigmented. The larvae were 

 described by Okiyama and Ueyanagi (1977). 



