Chaetodontidae: L III F2

Chaetodon blackburnii Desjardins 1836, C. dolosus Ahl 1923 & C. auriga Forsskål, 1775

Brownburnie;                                   Blackedged butterflyfish;   Threadfin butterflyfish

Egg diameter in µm	Number of oil globules	Diameter of oil globule in µm	Yolk texture	Perivitelline space	Position of oil globule at hatch	Gut length   at eye- pigment stage	Myomeres
700-745	1	170-180	clear	narrow	stern	62% of NL	24

Egg: This egg has a clear oil globule, which is astern in the yolksac of the unhatched embryo (A).The embryo has tiny black pigment spots evenly scattered dorsally along the whole body. The yolk has a rough surface. Incubation is about 26 hours.

Larva: The 1-day larva has yellow pigment dots, ventrally along the notochord, from head to tail, and dorsally, along the notochord, from the oil globule to beyond midtail (B). Black pigment intensifies, giving the larva a greenish tint, with a dark line running from eye to tail, ventrally, and from anus to tail dorsally (C, C1, C2).  Some larvae are distinctly darker than others, suggesting at least two species. The dorsal, ventral and caudal finfolds are peppered with fine black dots (C1). B: 1 day, C: 2 days, D: 4 days (23°C). Plate E shows a 4.5mm NL juvenile Chaetodon from a plankton saample collected off Park Rynie, species unknown.

Attempts at rearing this egg were unsuccessful. Ten larvae have been sequenced for DNA barcoding, 2 matching 3 adult C. blackburnii, 8 matching 4 adult C. dolosus, and 2 matching 2 adult C. auriga (all adults locally collected). The former two species are the two most common chaetodontids seen in 30-40m on reefs off Park Rynie, along with C. marleyi (FIIIA5). Chaetodon auriga is common on the Aliwal Shoal. Further careful separation for barcoding is needed to establish whether these three species can be recognised at the larval stage.

Linked samples	Offshore	Inshore
Eggs	1432	1300
Hits	147	143

This was a common egg off Park Rynie (Introductory Notes Table 3), and was found all year round (blue graph). It was also common in the DHM samples (green graph), where it showed a summer spawning peak. Egg catches off Park Rynie have remained fairly steady over the study period (white graph). The Park Rynie linked samples showed slightly more eggs offshore (52%), suggesting the adults are spawning mainly between the 20m and 30m depth contours. See Section 7.3 and Table 1 of the Introductory Notes, for more information on the linked samples.