Platycephalidae: M III A2

Onigocia oligolepis (Regan, 1908) & ?Thysanophrys celebica (Bleeker, 1854)

Large-scale flathead


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








49% of NL



Egg: Early eggs have their light amber oil globules widely scattered or clustered (A). The developing embryo and yolksac become increasingly covered in yellow and black pigment dots. This egg was routinely hatched, to use larval shape to distinguish it from MIIIA1. Incubation is about 40 hours.

Larva: The 1-day larva is elongate, with a long gut and prominent pale green edge to the finfolds (B), which intensifies, and becomes yellow, in the 10-day larva (D), and is retained at flexion (E). B: 1 day, C: 4 days, D: 10 days, E: 16 days, F: 38 days (24-25°C).

Nine larvae have been barcoded, two of which matched two adult O. oligolepis collected from the Aliwal Shoal (BOLD). The other 5 larvae indicate a second species, but no match has been found among locally collected platycephalids. The reared series featured above, came from a batch of 28 eggs taken in the DHM sample of 31 March 1994. Settlement occurred at about 30 days. The reared juvenile was tentatively identified as Thysanophrys celebica, but no adult sequences are available, to indicate whether this is correct. Identification remains tentative, pending further adult barcodes.


Linked samples Offshore Inshore
Eggs 58 71
Hits 24 43

But for mid-winter, this species spawns all year round off Park Rynie (blue graph). The egg was the 15th most common in the DHM samples (Introductory Notes: Table 2), where it showed a similar spawning pattern (green graph). Catches of the eggs have become less frequent off Park Rynie in recent years (white graph). The Park Rynie linked samples had more eggs inshore (55%), consistent with its presence in the DHM samples, and indicating spawning close inshore, inside the 30m depth contour. See Section 7.3 and Table 1 of the Introductory Notes, for more information on the linked samples