Busby and Ambrose Development of larval and juvenile Odontopyxis tnspmosa and Xemeretmus latifrons 



399 



Tucker trawls, sled trawls, and bottom trawls. Collec- 

 tions were made by the Vancouver Public Aquarium 

 (VPA), Oregon State University (OSU), University of 

 Washington (UW), NOAA's Southwest Fisheries Sci- 

 ence Center (SWFSC-CalCOFI program), and the 

 Alaska Fisheries Science Center (AFSC) from the years 

 1932 to 1991. Specimens are currently housed in the 

 larval fish collections of these institutions. Larvae and 

 juveniles were originally fixed in 3.5 or 5.0% formalin 

 and subsequently transferred and stored in 3.5% buff- 

 ered formalin or 70% ethanol. 



Larvae of 0. trispinosa and X. latifrons were identi- 

 fied using the serial approach. This method uses adult 

 characters to progressively link juveniles to smaller 

 specimens through a continuous sequence of shared simi- 

 larities. Pigmentation, head spination, body morphol- 

 ogy, dermal plates, and meristic features were all used 

 as diagnostic characters. Identification of adult and ju- 

 venile specimens was accomplished by using methods 

 of Miller and Lea (1972), Hart (1973), and Kanayama 

 (1991). Nomenclature and taxonomic classification of 

 the family Agonidae follow Kanayama (1991). Develop- 

 mental series were illustrated by using a camera lucida 

 attached to a dissecting stereomicroscope. 



Only melanistic pigmentation is described because 

 formalin fails to preserve color pigments. In the de- 

 scription of pigmentation, the term "band" refers to 

 any aggregation of melanophores that approximates a 

 vertically oriented rectangle. A "bar" also approximates 

 a rectangle but is horizontally oriented. A "patch" is 

 any other distinguishable aggregation of melanophores. 



Measurements 



The following measurements were made on 45 larvae 

 and early juveniles of 0. trispinosa and 45 larvae of 

 X. latifrons by using an ocular micrometer in a stereo- 

 microscope: 



Standard length (SL) — Snout tip to notochord tip 



prior to development of caudal fin, then to posterior 



margin of hypural element. (All body lengths in this 



study are standard lengths.) 

 Body depth — Vertical distance from dorsal to ventral 



body margin at pectoral-fin base. 

 Snout to anus length — Distance along body midline 



from snout tip to a vertical line through center of 



anal opening. 

 Head length (HL) — Snout tip to posterior edge of 



opercle (to pectoral-fin base in small larvae before 



opercular margin is visible). 

 Head width — Distance across head between dorsal 



margins of orbits. 

 Snout length — Snout tip to anterior margin of orbit 



of left eye. 

 Eye diameter — Greatest diameter of left orbit. 

 Pectoral fin length — Distance from pectoral-fin base 



to tip of the longest ray. 



Osteology 



Selected specimens were cleared and differentially 

 stained to identify cartilage and bone with alcian 

 blue and alizarin red-S (Pothoff, 1984). Skeletal ele- 

 ments and dermal plates were recognized as ossified 

 upon initial uptake of alizarin red-S. Twenty-seven 

 0. trispinosa (5.3^41 mm) and 12 X. latifrons (7.4- 

 39.2 mm) were cleared and stained for study. Counts 

 of meristic features were made on stained specimens 

 only. Not all stages of development were stained for 

 X. latifrons because specimens were limited. Preflexion, 

 flexion, and postflexion stage larvae were stained 

 (Kendall et al., 1984). Nomenclature of skeletal ele- 

 ments follows that used by Leipertz (1985) for X. 

 triacanthus. Plate nomenclature follows that of Gruchy 

 (1969) and is described in Figure 2. Terminology of 

 larval head spination follows that proposed for adult 



DLP 



LLP 



VLP 



Figure 2 



Terminology of bony plates in agonid larvae: DLP=dorsolateral; MDP=mid-dorsal; SLP=supralateral; LLP=lateral line; ILP=infralateral; 

 VLP=ventrolateral; MVP=mid-ventral (after Gruchy, 1969). 



