Leiognathidae: L III F5

Secutor ruconius  (Hamilton-Buchanan, 1822)

Pugnose soapy


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








35% of NL



Egg: The embryo in eggs about 12 hours old, has fine yellow dots and heavier stellate black dots down the body. The whole egg has a yellow tinge, seen on a white background. Near hatching, the yellow pigment spots are big and splashy, both on the embryo and oil globule, with a few on the yolk near the oil globule (B). The oil globule is clear. Incubation is 24-26 hours. Eggs are seen in 2 development stages; thus are probably spawned both morning and evening.

Larva: The oil globule position in the NH larva is astern, but not tightly so (C). The 1-day larva is easily confused with LIIIG4, and KIIIB3A, but the 2 & 3-day larvae can be positively distinguished by the presence of a diagonal line of small bumps in the dorsal and ventral finfolds, converging on the notochord posteriorly (F, black arrows; F1 black arrows dorsally, white arrows ventrally). By day 3-4, a supraoccipital crest is forming (G, black arrow above top specimen); is well developed in the 8-day larva (H), and persists at the onset of flexion in 14 days (I). Flexion is complete in the 23 day larva (J).  C: NH, D: 1 day, E: 2 days, F: 3 days, G: 4 days, H: 8 days, I: 14 days, J: 23 days, K: 43 days (25°C).

This egg was relatively easy to rear, made easier by the large batches of eggs collected. Some differences in pigment density suggested that there might be two species, but DNA will be needed to confirm this. Thirteen hatched larvae have been barcoded (BOLD), 8 of which match 7 adult S. ruconius (some submitted as S. insidiator in error). Five of the larvae match an adult submitted as Gazza minuta, but which has not barcoded with 7 adult Gazza minuta already sequenced. The identity of this specimen needs to be checked.

Linked samples Offshore Inshore
Eggs 1248 1317
Hits 55 129

Very much a summer egg off Park Rynie (blue graph). Also common in the DHM samples, where it showed a bigger October-November presence (green graph). Has become less abundant off Park Rynie in recent years (white graph). The Park Rynie linked samples showed an even balance of eggs, with slightly more in the inshore samples, indicating spawning well inside the 30m depth contour. See Section 7.3 and Table 1 of the Introductory Notes, for more information on the linked samples