Cheilodactylidae: K III A1

Chirodactylus jessicalenorum Smith 1980

Natal fingerfin

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
910-1030	1	220-260	clear	narrow	bow	53% of NL	33-35

Egg: Due to the 2-day incubation time, these eggs were collected quite fresh, or in the about-to-hatch state seen in A. When fresh, due to size and the amber oil globule, I most often confused them with Sarpa (LIIIB9), which is also a winter spawner, and Umbrina canariensis (LIIIA4). A day later, the oil globule under the embryo’s head, and the greenish tinge to the embryo’s pigment, identifies this egg (A), as does the pigment pattern in the egg, against a white background (A1). Incubation is about 40 hours.

Larva: The almost continuous yellow pigment down the length of the newly hatched larva, distinguishes this from the next species (KIIIA2). It is likely tht the two different pigment colours of B and C represent the two species revealed by barcoding (see notes below). By 3-4 days, a dark band of pigment has formed over the gut, and runs to the end of the notochord (E). A small patch of black pigment is seen dorsally near the notochord tip (D1). By day 5 this has extended forward to anterior to the anus, and the band over the gut has extended forward through the eye to the tip of the nose (F1). C: NH, D: 2 days, E: 3 days, F: 5 days, G: 12 days, H: 23 days (22°C).

This larva was reared to 23 days, at which stage it was just undergoing flexion (H), consistent with the known extended pelagic stage of cheilodactylids (Leis & Trynski 1989). No gill spines or pelvic fins were seen at this stage. Brownell (1979) reared a cheilodactylid, which he tentatively identified as Cheilodactylus fasciatus. This egg has more yellow pigment than Brownell's illustration, and so does the larva. Fourteen larval DNA barcode sequences are currently available, of which 11 match the sequence of 5 Chirodactylus jessicalenorum collected locally. But 3 larvae hatched from eggs collected in August 2007 match 6 adult Chirodactylus brachydactylus from our waters. Attempts to separate these two species at the egg stage are continuing.

Although of reasonable size from an angling perspective, this fish is not vulnerable to current angling pressure as it is rarely caught on baited hooks. It is however, targeted  by spear fishermen, operating from ski-boats, on the offshore pinnacles.

This cheilodactylid is a winter spawner in our waters (blue graph). In the DHM samples, the egg was only seen twice, both in mid-winter (July-August). At Park Rynie, the egg has remained common throughout the study period (white graph). In the Park Rynie linked samples, the eggs were more common offshore (75%), indicating spawning inside the 40m contour. See Section 7.3 and Table 1 of the Introductory Notes, for more information on the linked samples.

Linked samples	Offshore	Inshore
Eggs	2057	689
Hits	66	70