RICHARDSON and JOSEPH: LARVAE AND YOUNG OF BOTHIDS 



throughout development in three body regions: 

 head, abdominal, and tail. 



E. microstoums - Head Region 



The eyes of the smallest specimens examined 

 (2.3 mm) are pigmented. The head of early 

 stage lai*vae, 2-3 mm, is marked by a few melan- 

 ophores scattered along the lower jaw and on 

 the ventral body margin from the angle of the 

 lower jaw to the cleithrum (Figure 2A). The 

 concentration of ventral pigment increases with 

 age to about 8-9 mm (Figure 3) and then de- 

 creases (Figure 4), although it may vary con- 

 siderably among individuals. A group of melan- 

 ophores is usually noticeable on the postero- 

 ventral angle of the lower jaw and sometimes at 

 the tip of the cleithrum in larvae over 3 mm 

 (Figures 3, 4). Melanophores occur over the 

 hindbrain and midbrain singly or in groups in 

 larvae from 3.5 mm up to metamorphosis 

 (Figures 3, 4). Larvae over 8 mm have addi- 

 tional scattered melanophores around the 

 snout and upper jaw and on the operculum. 

 An internal pigment spot may be seen beneath 

 the lobe of the hindbrain by about 8 mm 

 (Figure 3D). A single stellate melanophore 

 appears on the operculum anterior to the base 

 of the pectoral fin at about 10-11 mm (Figure 

 4A, B). 



Figure 2. — Early stage larvae of A) Eiropus microstomus 

 (2.5 mm SL) and B) Citharichthys arctifrons (2.5 mm SL). 



After metamorphosis and with scale forma- 

 tion, head pigmentation becomes less pro- 

 nounced. A general darkening occurs on the 

 lips and over the brain (see Figure 7A). Later 

 the snout darkens and pigmentation increases 

 on the operculum. 



£. microstomus -Abdominal Region 



Most conspicuous is the pigmentation, which 

 persists until metamorphosis, on the gas bladder 

 (Figures 2 A, 3). This pigment area spreads out 

 onto the hindgut with the disappearance of the 

 gas bladder (Figure 4B, C). Melanophores 

 line the ventral body margin from the cleithrum 

 to the hindgut in early stage larvae (Figure 2A). 

 After the pelvic fin begins to form (5-7 mm), 

 melanophores no longer line the ventral body 

 margin at the base of the fin but increase in 

 concentration under the gut (Figures 3D, 4A). 

 Several diffuse melanophores, the number in- 

 creasing with age, appear over the end of the 

 hindgut at about 3 mm (Figure 3A). One or 

 two stellate melanophores are visible on the 

 pectoral fin near its ventral origin throughout 

 the larval period. Scattered melanophores ap- 

 pear on the distal margin of the pelvic fin after 

 it forms. Two or three characteristic internal 

 pigment spots appear along the dorsal surface 

 of the notochord above the gut cavity at about 

 4 mm and remain until metamorphosis. A 

 pigment spot appears on the dorsal body margin 

 above the gut cavity at about 3 mm (Figure 3A). 

 It persists until metamorphosis, although later 

 it is located on the proximal margin of the inter- 

 neural musculature (Figure 4 A, B). As the lar\^a 

 approaches metamorphosis, pigmentation ap- 

 pears and increases along the myosepta of the 

 body (Figure 4B,C). 



After metamorphosis, the gut cavity becomes 

 darkened on the eyed side. Pigmentation in- 

 creases on the pectoral and pelvic fins (Figures 

 7 A, 8A). Pigmentation along myosepta dis- 

 appears on the body but increases on the inter- 

 neural and interhemal regions in juveniles. 



E. microstomus - Tail Region 



Larvae of 2.3 mm have a band of pigment 

 about two-thirds the distance from the anus to 



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