Paralichthyidae: L III C9

Pseudorhombus arsius (Hamilton-Buchanan, 1822).

Largetooth flounder

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
840-940	1	120-170	clear	narrow	stern	48% of NL	35

Egg: When seen fresh, this egg can be confused with LIIIC3, KIIIA4 and KIIIA8, because all four have a relatively small oil globule, for this size egg. Later, the appearance of fine yellow pigment on the larva and yolk, which becomes greener as the egg develops, excludes KIIIA4. The eggs often hatch while sorting in the evening of collection, but are occasionally seen fresh. The oil globule is light amber, and the egg sometimes appears slightly oval.  Incubation is 25-35 hours.

Larva: The NH larva (B) has green pigment forming curious patterns in the finfolds, interspersed with black dots. The pigment pattern becomes brown by day 4, but the intensity and pattern remains essentially the same (D). The larva curls when disturbed. B: NH, C: 1 day, D: 2 days, E: 4 days (22-24°C). Plate B1 shows the NH larva of LIIIC3, to illustrate the difference.

This species has not been reared, made more difficult by the low numbers usually seen in samples. Six larvae have been sequenced, 4 of which have matched the sequence of 3 adult P. arsius from the KZN coast (BOLD).The sixth larva has matched another Pseudorhombus, probably not P. natalensis, which as accounted for (LIIIE9).

This egg was uncommon off Park Rynie, but was seen most months of the year (blue graph). It was seen on 5 occasions in the DHM samples (green graph). Annual abundance of the eggs off Park Rynie has remained fairly steady, apart from an unusual sample in 1998 (white graph). The Park Rynie linked samples showed the majority of eggs inshore (71%), suggesting the bulk of spawning occurs inshore of the 20m depth contour. This species is frequently

linked samples	Offshore	Inshore
Eggs	33	81
Hits	21	34

netted from Durban’s Addington beach, by local seine-netters. See Section 7.3 and Table 1 of the Introductory Notes, for more information on the linked samples.