Beach, Calif. (7.5 mm), in 1977; by otter trawl in 

 Marina del Ray, Calif. (12.0 mm), in June 1977: 

 and from the larval fish collection of the Harbors 

 Environmental Projects (University of Southern 

 California) taken by horizontal plankton tows in 

 Los Angeles Harbor (specimens collected in 

 1972-73). A total of 32 larvae from 2.6 to 7.5 mm of 

 G. rhessodon were examined for larval charac- 

 teristics. An additional 311 larvae ofG. rhessodon 

 (2.9-7.5 mm) from King Harbor were checked spe- 

 cifically for the presence of melanophores on the 

 head. Larvae were examined and drawn using a 

 Wild'* stereomicroscope fitted with a camera 

 lucida. Standard length (SL) was measured from 

 the tip of the snout to the tip of the notochord until 

 completion of notochord flexion and then to the 

 posterior margin of the hypural plate. 



Results and Discussion 



Gohieiox rhesiiidiiti 



The most distinctive character of G. rhessodon 

 larvae was the presence of 8-17 (mean 12) stellate 

 melanophores, which ran laterally in two or three 

 rows from the pectoral fin region to just posterior 

 to the anus (Table 1, Figures 1-3). The dorsum of 

 the gut was also heavily pigmented with stellate 

 melanophores (not included in the lateral 

 melanophore counts). The gut pigmentation often 

 obscured the well-developed swim bladder. Myo- 

 mere counts ranged from 24 to 29 (mean 27) but 

 were difficult to count, especially in early stages. 

 All specimens up to 6.9 mm had four to seven 



■•Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



Table l. — Summary of larval measurements and adult counts 

 for Gobiesox rhessodon andRtrnicola muscarum (Miller and Lea 

 1972 and present study). 



regularly spaced melanophores along the ventral 

 portion of the tail region. The length of the gut 

 averaged approximately 35*7^ of body length in all 

 specimens examined. Head length ranged from 19 

 to 25'7f SL in most specimens <6.5 mm. Individu- 

 als 5^6.5 mm had a much larger head of about 33'7f 

 of SL. All specimens had a stellate melanophore at 

 the base of each pectoral fin which was covered by 

 the opercular flap in later stages ( >6.9 mm). The 

 larvae from Catalina and Los Angeles Harbor pos- 

 sessed from zero to four spots on the dorsal portion 

 of the head. Forty-two percent (mean 24, range 

 2.6-6.9 mm) of the larvae had head pigmentation 

 in the form of spots. Of the larvae examined from 

 King Harbor, 79^f (mean 311) lacked this head 

 pigmentation. The larvae with and without head 

 spots were very similar in every other respect. 



The larvae of G. rhessodon hatched at about 4.0 

 mm (three specimens ranged from 3.9 to 4.1 mm) 

 from attached, monolayered eggs laid under rocks 

 and cobble in the intertidal zone at Catalina Is- 

 land. Nest guarding adults have been found from 

 spring to early summer by Lavenberg.^ The rela- 

 tively advanced larvae possessed well-developed 

 jaws and pectoral fins at hatching and a laterally 

 bilobed yolk, which was absorbed within the first 

 24 h. The gut had two or three constrictions giving 

 it the appearance of being looped. The constric- 

 tions were characteristic of the larvae up to 6.9 

 mm. Notochord flexion occurred between 5.5 and 

 6.9 mm, and caudal fin rays started to develop just 

 prior to flexion. Dorsal and anal fin ray develop- 

 ment began around 6.2 mm and the fins were de- 

 veloped sufficiently for positive identification at 

 about 6.9 mm. The development of the pelvic fins 

 began at 5.5 mm and the characteristic suction 

 disc was formed at about 7.0 mm. Transformation 

 and settling probably occur between 8 and 12 mm 

 as evidenced by an 8-mm planktonic specimen 

 from King Harbor that possessed juvenile pigmen- 

 tation (McGowen see footnote 2) and the 12-mm 

 juvenile (Figure 3) which was collected by benthic 

 otter trawl. This latter specimen exhibited the 

 ability to cling to surfaces after capture. 



Larvae of G. rhessodon appear to be the most 

 common Gobiesox encountered in several near- 

 shore plankton sampling programs in southern 

 California (Brewer see footnote 1; McGowen see 

 footnote 2; White see footnote 3). This is to be 

 expected in that previous species lists of adult/ 



'Lateral melanophores obscurred myomeres so that accurate counts could 

 not be taken 



^Counts from Los Angeles County Museum specimen X-rays — G rhessodon 

 (LACM1998), (ourspecimens, R rrruscarum (LACMW70-16). six specimens 



^Robert J. Lavenberg. Curator of Fishes. Los Angeles County 

 Museum of Natural History, Los Angeles, CA 90007. Pers. com- 

 mun. June 1977. 



301 



