Jordan and Bruce: Larval development of three roughy species 



Spination Aulotrachichthys larvae have well-developed 

 head spination. Our smallest specimen has a low 

 supraocular ridge with a single spine. The number of 

 supraocular spines increases to 3-4 by 4.4 mm 

 (Fig. 3C); they become quite robust and reach a maxi- 

 mum number of 8-9 during flexion. Generally, the pos- 

 terior group of these spines are the largest and are 

 recurved. Preopercular spines are present by 4.4 mm, 

 with an anterior preopercular series added by 4.9 mm. 

 By 5.7 mm, preopercular spination is quite robust, with 

 secondary ridging and branching of the largest spines 

 (particularly at the angle) (Fig 3D). Nuchal, supra- 

 cleithral, and posttemporal spines, as well as nasal 

 and cranial ridges, are developed prior to 5.7 mm. 

 During flexion a hard bony plate forms in the region of 

 the posttemporal, extending posteriorly to the level of 

 the opercular margin. This plate extends beyond the 

 opercular margin by 7.9 mm, and is retained in the 

 adult. Available specimens are insufficient to deter- 

 mine if this plate results from the fusion of the 

 supracleithral and posttemporal series. During flexion, 

 spines also develop on the dentary and infraorbital. 

 Several cranial and opercular ridges appear at this 

 stage. 



A single spine is present immediately posterior to 

 the anus by 4.9 mm. Dermal spines are present on the 

 pelvic bases by 5.7 mm, and by 7.9 mm a cluster of 

 spines is also present immediately anterior to the anus. 

 The 7.9 mm specimen has well developed dermal 

 spination in longitudinal rows over the entire body 

 surface and on the dorsal- and anal-fin bases, although 

 there is no sign of scalation. Additionally, this speci- 

 men has a row of strong spines extending posteriorly 

 along the ventral midline from the anus towards the 



anal fin, probably precursors to the ventral scutes of 

 adults. Fine villiform teeth are present in both jaws. 



Pigmentation Aulotrachichthys larvae are heavily pig- 

 mented (with the exception of the posteriormost 5-6 

 myomeres, including the notochord tip) throughout the 

 larval period. The pelvic fins are heavily pigmented in 

 the smallest specimen and remain so in the 7.9 mm 

 specimen. Aulotrachichthys larvae are more heavily 

 pigmented than Paratrachichthys, although, as with 

 Paratrachichthys, there are few useful distinguishing 

 characters based on pigment pattern. 



Optivus sp. (Fig. 4) 



Morphology Body depth increases to a maximum 

 of 49% body length during flexion (Table 4). Body 

 depth at anus increases only slightly compared with 

 Paratrachichthys and Aulotrachichthys, because the 

 anus position in Optivus remains static. Head length 

 increases from 36% body length in preflexion larvae to 

 44% in juveniles. Eye diameter remains relatively con- 

 stant. The mouth is moderate to large, reaching to the 

 center of the eye in our smallest specimen (2.5mm) 

 and beyond the eye in larvae greater than 4.0 mm. 

 The gut, which is initially straight, quickly thickens, 

 coils, and becomes broadly triangular by 3.5 mm. 

 Optivus larvae do not develop a light organ. Notochord 

 flexion commences at about 4.0 mm and is complete by I 

 7.1mm. There are 27-29 myomeres. 



Fin development Pelvic fins first appear in larvae of 

 3.0 mm as slight swellings on either side of the gut. 



