586 



ONTOGENY AND SYSTEMATICS OF FISHES- AHLSTROM SYMPOSIUM 



Table 151. Chae^acters Useful for the Separation of Gobioid Larvae to the Family Level. Characters present at least during postflexion 

 stage. 



' Larvae unknown, character states projected from adult conditions. 



useful in distinguishing gobioid larvae at all levels. The sequence 

 of fin development is similar in most gobioids. although it vaiies 

 somewhat in eleotrids and gobioidids. Numbers of fin rays and 

 spines vary greatly among the gobioids and are particularly use- 

 ful in distinguishing gobioids at the family and species levels 

 (Hoese-). Degree of fin development at different sizes is helpful 

 in separating certain species of larvae, particularly if complete 

 developmental series are available. 



Median finfolds and pectoral fins are present at hatching or 

 develop in early larvae of all known gobioids. The pelvic fin is 

 the last fin to form, usually beginning during the flexion or 

 postflexion stages. 



The caudal fin is the first fin to form diflTerentiated rays, be- 

 ginning during the flexion stage. Gobioids usually have 17 seg- 

 mented principal caudal rays and numerous secondary rays that 

 are usually all differentiated by the postflexion or transforming 

 stages. 



The second dorsal and anal fins are next to develop in eleo- 

 trids, gobiids, and microdesmids. The anterior and middle ele- 

 ments are first to form and development generally proceeds 

 posteriorly. It is difficult to distinguish the dorsal spines from 

 rays in the continuous dorsal fin of microdesmids during the 

 larval stages, but they are usually shorter than the rays. The first 

 element of the anal fin and the first element of the second dorsal 

 fin initially develop as rays, but later transform into spines in 

 most eleotrids and gobiids. The presence of a continuous (Afi- 

 crodesmus longipinnis. Fig. 311) or separated (Gobiidae Larva 

 2, Fig. 309) dorsal fin is useful in family diagnosis of gobioids. 

 This character varies considerably from the continuous dorsal 



 Hoese (this volume) provides a meristic table for gobioid families. 



in microdesmids, gobioidids, and trypauchenids to the widely 

 separated fins of the gobiid Periophthalmus cantonensis (Ko- 

 bayashi et al., 1973). 



The first dorsal and pectoral fins are usually next to complete 

 development in microdesmids and gobiids, while the full com- 

 plement of first dorsal spines is last to form in eleotrids. While 

 complete developmental series of eleotrids are sparse, it appears 

 that the posteriormost first dorsal spines form after the full 

 complement of pectoral and pelvic fin elements are present (e.g., 

 Dormitator maculatus, Eleotris ptsonis. and Erotelis smarag- 

 dus). Inthegobioidid, Taenoides cirratus (9 .3 mm), Dotsu(1958) 

 depicts the pectoral fin to be the last fin to obtain its full com- 

 plement of elements. First dorsal spines range from 2 or 3 in 

 some gobiids (e.g., Claringer cosnmrus) to 28 in some micro- 

 desmids (e.g., Microdesmus longipinnis). The gobiid Luciogo- 

 bius elongatus (Fig. 309) lacks a first dorsal fin entirely (Shiogaki 

 and Dotsu, 1972c). Pectoral fin rays range from 3 to 26. 



In known gobiids, trypauchenids, and microdesmids the pel- 

 vic fin is last to form and complete development. Development 

 of the pelvic fins in gobioids varies greatly between families and 

 within certain families such as the gobiids. Some gobioids have 

 strongly united pelvics that form a cup-shaped disc (Fig. 309) 

 at a very early age, while adult Rhyacichthys aspro (Rhyacich- 

 thyidae) have widely separated pelvics. Eleotrids, trypauchen- 

 ids, microdesmids, kraemeriids, and gobioidids usually have 

 separated or weakly united pelvics. Pelvic fins in gobiids range 

 from strongly united, forming a disc to weakly connected at the 

 base to totally separated (usually in species with reduced pelvics; 

 Fig. 309). The size at which pelvics develop is an important 

 character in the separation of some gobiid genera and species. 

 One pelvic spine and 2-5 rays occur in gobioids. Expedio par- 

 vulus (Gobiidae) lacks pelvic fins entirely (Fig. 310). 



