Haemulidae: E III A4

Plectorhynchus chubbi (Regan, 1919).

Dusky rubberlip

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
940-960	1	215	segmented	narrow	bow	60% of NL	24

Egg: This egg has a clear oil globule (A), and yellow pigment dots are spread evenly over the embryo, in a ring around the oil globule, and a few dotted on the yolk. Black pigment dots follow the same pattern but are ventral on the oil globule. Plate A1 shows a slight variation, with the oil globule smothered in yellow pigment.

Larva: The larva is more deeply bodied than that of Decapterus and Trachurus (EIIIA6), B: NH (ORI), B1: 1 day (Park Rynie), C: 3days (ORI), D: 4 days (Park Rynie).

This species was first seen in a sample of eggs taken from the main tank at the ORI, Durban, during February 1993, when I was doing some collaborative work with Dr Pat Garratt, on rearing slinger (Chrysoblephus puniceus) and soldier (Cheimerius nufar) from eggs spawned in the main display tank. Preliminary identification was a process of elimination, based on the species in the main tank, and the fact that the oil globule position, segmented yolk and pigment in the finfolds at first hatching, all pointed to a carangid or haemulid. In the plates above, the specimens from ORI have deliberately been mixed with specimens from Park Rynie. The ORI 3-day larva is malformed, but there are other differences which could suggest two species.

A single larva, collected in February 2011, has been barcoded, and it matches the sequence of adult Plectorhynchus chubbi, which fits the above criteria, including being present in the ORI main tank at the time. However, confirmation must await further sequences.

The position of the oil globule in newly hatched larvae is not infallible, and occasional specimens, in some species more than others, are seen where it is misplaced. On occasion, specimens of Dinoperca petersi (FIIIA2) have been seen, which have the oil globule displaced towards the bow. In such cases confusion with P. chubbi will occur. However, in FIIIA2, the gut is distinctly shorter, in the 4-5 day larva.

This species has only been seen on 6 occasions at Park Rynie, but along with the January sample from ORI, suggests a summer spawner (blue graph).