Ambassidae: K III B9C

Ambassis natalensis Gilchrist & Thompson, 1908.

Slender glassy

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
600-670	1	190	clear	narrow	bow	30% of NL	24

Egg: This egg was collected with a surface skimming plankton net in the Msimbazi estuary, on 27 November 2003, when ripe running females of A. ambassis were encountered while cast-netting for adult DNA material. The mouth of the estuary was closed at the time, surface salinity was 13.5‰, and the temperature was 28°C.  The eggs were not seen to develop the dense yellow pigment on the embryo, as noted in KIIIB9, but the oil globule is a similar size relative to egg diameter (A). In some, the darkening of the light amber oil globule, with black pigment, is apparent.

Larva: The NH larva has pale yellow pigment behind the eyes and in a patch midtail (B), and dark pigment dorsally on the notochord in midbody. By day 2, most pigment had disappeared (C), and the 4-day larva showed just a few spots of  yellow pigment on the head, and dark pigment over the gut (D). B: NH, C: 2 days, D: 4 days (23°C).

Given the presence of ripe running female A. ambassis at the time, it is assumed these eggs belong to this species. The low salinity water fits the profile of the species, compared to the other two Ambassis in KZN waters (S. Weerts, CSIR, Durban pers. comm.). Barcodes of larvae from KIIIA9B have however proved to be Ambassis ambassis, which points to the likelihood that this is Ambassis natalensis. Identification is tentative, pending barcodes from hatched larvae.