NOTE De Forest and Busby: Development of larval and early iuvenile Apodichthys flavidus 



477 



Puget Sound, WA, and from 

 adjacent waters. Specimens 

 were initially preserved in 

 3.59f buffered formalin solu- 

 tion and later transferred 

 to 70% ethanol (Busby et 

 al., 2000). A dissecting ste- 

 reomicroscope was used to 

 examine pigmentation, gen- 

 eral body size and struc- 

 ture, and to obtain meristic 

 counts. Morphological mea- 

 surements were made on 

 55 suitable specimens by 

 using a digital image anal- 

 ysis system consisting of a 

 video camera attached to a 

 dissecting stereomicroscope 

 and a computer with image 

 analysis software. All mea- 

 surements were taken from 

 the left side of the speci- 

 men. Standard length was 

 used throughout the study 

 unless otherwise indicated. 

 During flexion stage, noto- 

 chord length (NL) was mea- 

 sured and recorded as SL. 

 Measurements included 

 standard length, head 

 length, eye diameter, body 

 depth, snout to anus length, 

 and pectoral-fin length, as 

 described by Moser (1996). 

 To describe osteological 

 development of A. flavi- 

 dus, with emphasis on the 

 development of the caudal 

 skeleton, 12 specimens were 

 cleared and stained by us- 

 ing the technique described 

 by Potthoff (1984). The 

 terms "unossified precur- 

 sor" or "element" are used 

 to describe unossified ele- 

 ments that took up alcian 

 blue stain but not alizarin 



red-s stain. From the cleared and stained specimens, 

 stages of larval development were identified from land- 

 marks of caudal-fin development. Caudal skeletons of 

 six specimens representing distinct stages were used to 

 create illustrations. Developmental stage terms follow 

 Kendall et al. (1984) and Neira et al. (1998). The flexion 

 stage was divided into three additional stages: early-, 

 mid- and late-flexion. Early-flexion begins at hatch- 

 ing, mid-flexion begins with the formation of the forth 

 hypural and epurals, and late flexion begins with the 

 development of the flfth hypural and ends with complete 

 notochord flexion. Nomenclature of caudal skeleton ele- 

 ments follows Fujita (1989). 



14 5 mm 



^^^--—^^^^^^^ 



'"^^ 



"~~~^~'^S^^ 



37.0 mm 



Figure 1 



Developmental series of penpoint gunnel i Apodichthys flavidus)AA) Early-flexion 

 larva. Clam Bay, 6 April 1989 (UW 104928): (B) mid-flexion larva (from Matarese 

 et al., 1989); (C) late-flexion larva, Friday Harbor, 20 April 1994 (UW 104930); (D) 

 postflexion larva. Clam Bay, 20 April 1989 (UW 104932): (E) juvenile, Sequim Bay, 

 2.5 April 1989 (UW 104934). Illustrations by Beverly Vinter. 



Results 



Morphology 



Apodichthys flavidus larvae are approximately 12.0-13.0 

 mm at hatching and in early flexion stage and have 

 little or no yolk sac present (Fig. lA). The early-flexion 

 stage occurs between hatching and 14.0 mm. Mid-flexion 

 begins at approximately 14.0 mm (Fig. IB), late-flex- 

 ion at 17.0 mm (Fig. IC), and postflexion at 20.0 mm 

 (Fig. ID). Transformation to the juvenile stage occurs 

 between 25.0 mm and 30.0 mm. Juveniles examined 

 ranged from 30.1 to 42.3 mm and looked like small 



