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








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. Thirteen larvae have been barcoded, 11 of which match 5 C. lida collected locally, 4 catalogued under the code MIIIA8. Two matching larval sequences do not match any species currently in BOLD, but cluster among the cynoglossids.

Although eggs were collected off Park Ryniein all months (blue graph), there is a summer peak. The annual catch was erratic (white graph), with 1988 and 2006 overshadowing an otherwise sparse presence. Perhaps the muddier offshore sediments resulting from the September 1987 floods, and 2005 rains, were beneficial to this species. The egg was not seen in the DHM samples.

Linked samples Offshore Inshore
Eggs 6 151
Hits 5 14

The Park Rynie linked samples were biased by two big inshore samples, but even with these reduced to 1 egg each, had 79% in inshore samples, pointing to spawning in very shallow water. See Section 7.3 and Table 1 of the Introductory Notes, for more information on the linked samples