Cynoglossidae: M III A6

Cynoglossus lida (Bleeker, 1851).

Roughscale tonguefish

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
770-960	multiple	NA	clear	narrow	scattered	34% of NL	ca 50

Egg: The clear to light amber oil globules are usually evenly distributed in the yolk (A), and the early embryo has two lines of fine black pigment dorsolaterally. The embryo later becomes covered in yellow pigment spots, with some on the yolk (A). The eggs are difficult to separate from MIIIA1 and MIIIA2, as well as MIIIA8 at the smaller end of the size range, and always require hatching to confirm. The incubation period is about 30 hours.

Larva: The NH larva is elongate, with a distinctive yellow pigment pattern, which remains similar for the next two days (B). The first elongate dorsal ray forms by day 5 (C), and the bud of a second is visible at day 12 (E). The 30-day, postflexion larva, has a well developed rostral bulb (precursor to the rostral hook; Leis  & Trnski 1989), at the base of the elongated dorsal rays (F). The specimen in Plate F, was photographed from its right side, to show that the right eye is just beginning to migrate to the left side of the head. B: 2 days, C: 3 days, D: 5 days, E: 12 days, F: 30 days (22°C).

This egg was only reared once, and the 30-day larva was preserved as a voucher specimen. Nine larvae have been barcoded, 8 of which match 2 C. lida collected locally. One larval sequence does not match any species currently in BOLD, but clusters among the cynoglossids..

This egg was too rare off Park Rynie, to show a distinct spawning pattern (blue graph), although there is a suggestion of a summer peak. The annual catch was erratic (white graph), with 32 eggs in 1988 overshadowing an otherwise sparse presence, a pattern very similar to the previous species (MIIIA5). Perhaps the muddier offshore sediments resulting from the September 1987 floods were beneficial to these two species of flatfish. The egg was not seen in the DHM samples. Only 6 eggs were seen in the Park Rynie linked samples, 4 offshore and 2 inshore. See Section 7.3 and Table 1 of the Introductory Notes, for more information on the linked samples.