Stomiiformes: F I A2

Opostomias micripnus (Gunther, 1878)
Scaleless dragonfish

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








69% of NL

Ca. 55

Egg: When found newly spawned the PVS is wide, comprising 54-57% of egg diameter, but it closes as the larva develops (A). In some specimens the oil globule is clear, in others amber tinted. In all cases the egg was identified by the curious pinched and distorted shape of the oil globule (A). A dense band of black and yellow pigment develops ventrally along the larva prior to hatching. Incubation time is uncertain, but one egg took 72 hours to hatch (25°C)

Larva: The newly hatched larva is very elongate, with unpigmented eyes and unformed mouth (B). The front arrow points to the oil globule; the other to the anus (B). Eyes are pigmented by day 4 (C). Gut length has shortened to 61% by day 6 (E). B: NH, C & D: 4 days, E: 6 days.

Although this egg was not seen from 2000-2005, two found in August 2006 have been barcoded. No match has been found among the South African adult material. A wider search has found a match with Opostomias micripnus (Melanostomiidae) from New Zealand, for the 2006 pair of eggs (BOLD).

This egg has only been seen on 12 occasions in the Park Rynie samples, but the data suggests the fish is a summer/autumn spawner (blue graph). The collection amounts to 17 eggs, of which only 1 was in an inshore sample, implying spawning occurs in or over deep water, as is well documented for Melanostomiidae. See Section 7.3 and Table 1 of the Introductory Notes, for more information on the linked samples. The presence of these eggs in surface plankton samples off Park Rynie is probably indicative of a "Natal Pulse" passing through the area, pulling cold deep water up onto the shelf. See Section 3.4.2 of the Introductory Notes for more information on the "Natal Pulse".