584 



ONTOGENY AND SYSTEMATICS OF FISHES-AHLSTROM SYMPOSIUM 



Fig. 310. Larvae of gobiids from top to bottom: E.xpedio parvulns. 12.0 mm SL (redrawn from Shiogaki and Dotsu I971e); Astrabe lactisella, 

 11.1 mm SL (from Dotsu and Shiogaki 1971); Gobionellus beleosoma. 8.6 mm SL. (GCRL:02038). 



The gut is generally straight and extends to about midbody 

 or just beyond (~50% to 65% SL) in most gobioids (Figs. 309- 

 311), although in many species the gut is slightly looped just 

 anterior to the vent as in Microgohius thalassinus (Fig. 309). In 

 the trypauchenid, Trypauchen microlepis (Fig. 311). the gut is 

 considerably shorter (~39% SL) than in other gobioids. 



A prominent feature of gobioid larvae is a large gas bladder, 

 usually situated slightly anterior of midbody (Fig. 309). The gas 

 bladder is located just posterior to the pectoral fin in Trypauchen 

 microlepis (Fig. 311) and is smaller and less pronounced than 

 in most other gobioids. In small larval microdesmids ( <4.0 mm) 

 the gas bladder is located at about mid-gut, while in larger larvae 

 it is found about midbody, near the posterior portion of the gut 

 (Fig. 311). The prominent gas bladder in larvae usually disap- 

 pears by the juvenile stage, but is retained in the adults of some 

 species such as Gobiosoma atronasum (Colin, 1975). 



Eyes of known gobioid larvae are basically round or slightly 



ovoid in shape. The elongate gobioids such as the microdesmids 

 and gobioididshave small eyes (<20% HL) while most eleotrids 

 and gobiids have somewhat larger eyes (>20% HL). 



The head is of moderate length (~ 16% to 34% SL), generally 

 slightly rounded and gently sloping. The shape of the head changes 

 drastically in many species as they transform into juveniles. In 

 microdesmids such as Microdesmus longipinms and Gunnelli- 

 chthys sp. the lower jaw becomes hooked and protruding during 

 the later pelagic larval stages (Fig. 311). 



The lengths of dorsal and anal fin bases vary considerably 

 and are useful in the separation of gobioid larvae at various 

 taxonomic levels. The lengths of the fin bases are related to the 

 number of elements and/or the spacing between the individual 

 elements, which varies considerably. Trypauchenids, micro- 

 desmids, and some gobioidids, all have long dorsal and anal fin 

 bases (Fig. 311). Some eleotrids (Eleolris pisonis and Erotelis 

 smaragdus) and various gobiids (Rhinogobius similus. Yono- 



