Pempheridae: M II A5
Parapriacanthus ransonneti Steindachner, 1870 (and Pempheris adusta Bleeker, 1877).
Slender sweeper and dusky sweeper
|
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 |
|
1100-1200 |
multiple |
NA |
clear |
narrow |
Scattered ventrally |
54% of NL |
25 |
.
Egg: This egg is sticky, and in plankton samples, usually has a few items, such as strands of the blue-green alga Trichodesmium, adhering to it. Early eggs usually have the oil globules scattered on the perimeter (A). Later embryos have bright yellow pigment spots all over, and a few are scattered on the yolk surface (B). The oil globules are small and scattered. Fine black spots are seen on the embryo. Incubation is 45-50 hours.
Larva: The NH larva is distinctive among eggs with multiple oil globules (C), and the separate oil globules are still visible in the yolksac. The pelvic fin buds appear by day 4 (E, black arrow on lower specimen), and are brightly pigmented by day 5 (F). C: NH, D: 2 days, E: 4 days, F: 5 days (24°C). Note: the white patch in the dorsal finfold of the upper larva in Plate E is not pigment, but due to the larva dying under anaesthetic.
Efforts to rear this larva were unsuccessful. Five larvae have been sequenced, 4 of which match the sequence of 5 adult P. ransonneti collected locally (BOLD). The other 2 match 4 adult Pempheris adusta*, suggesting that this species also has a multiple oil globule when fresh (but see L II A2).
* The genus is currently under review and this species will very likely be separated from P. adusta, and assigned a new name in the same genus (J Randall, pers.comm. June 2014).
| Linked samples | Offshore | Inshore |
| Eggs | 226 | 144 |
| Hits | 59 | 79 |
These eggs were seen all year round (blue graph), but have shown a curiously erratic annual presence off Park Rynie over the study period (white graph). The egg was not seen in the DHM samples. The Park Rynie linked samples had more eggs offshore (61%), but the percentage is low, indicating spawning inshore of the two indicator species, in the region of 30m water depth. See Section 7.3 and Table 1 of the Introductory Notes, for more information on the linked samples.