Gulf Pipefish, Stigmatopora narinosa Browne & Smith 2007

Endemic to temperate waters of South Australia. The Gulf Pipefish is known only from Spencer Gulf and Gulf St Vincent, preferring areas with low turbidity and a patchy substrate of brown algae and sparse seagrass at 1-5 m.

Dorsal fin 37–45; Pectoral fin 12–13; Anal fin 2; trunk rings 17–19; tail rings 58–74; subdorsal rings 12.5-9.0 + 7.25–9.0 = 18.5–22.5.
 
Body very elongate, trunk shallow, not conspicuously broad in adult females; head aligned with body; snout laterally flattened and dorsally elevated, length 56–65% HL, depth 10–17% snout length; superior trunk and tail rings continuous; inferior trunk and tail rings continuous; lateral trunk ridge not confluent with lateral tail ridge, ending about 1.5 rings posterior to anal ring; tail not prehensile but very slender and flexible; longitudinal opercular ridge usually present in juveniles, not evident in adults.

Dorsal fin closer to tip of snout than to tip of tail, origin on 6th–8th trunk ring; anal fin tiny, below middle of dorsal fin; caudal fin absent; pectoral fin present.

Colour variable, usually greyish-green above with reddish-brown to dark brown transverse bands centred on the joints between the rings; bands distinctly broader ventrally, and disrupted in some, leaving a mottled pattern; tail tip often red. Juveniles often brown or golden.

Feeds on tiny crustaceans such as mysid shrimps.

Oviparous with eggs brooded by the males in a semi-enclosed pouch under the anterior part of the tail that extends for 15-18 rings from the anal ring; pouch plates absent or vestigial; well developed pouch folds meet on the ventral midline; males likely to be brooding at 113mm TL.
 
The eggs are deposited in two layers, a basal layer and an external layer. the maximum recorded brood size is 98 eggs.
 
Larvae: body rings are present at an early stage, reduced anal fin; TL at hatching 18mm.

The specimen with the greatest recorded number of eggs had 3 staggered rows of 64 basal membranous egg compartments on the tail, with the basal layer of eggs covered by a membrane with matching rows of egg pouches; the second layer with 34 eggs within the brood pouch folds resulted in a total of 98 eggs. 

Males  have extended brood patches from December to March, and juveniles < 9.0 cm are seen from December to March. Males  mature at 11.3 cm (Browne & Smith 2007).

Stigmatopora narinosa differs from S. nigra in having 9 rather than 6 sub-dorsal tail rings, a greater average number of dorsal rays (40.8 versus 36), subdorsal tail rings (9.08 versus 6.23) and subdorsal rings (19.8 versus 16.8).

Although S. narinosa and S. argus both have elongate narrow and shallow snouts, S. narinosa has a shorter, wider and more elevated snout. The brood pouch of S. narinosa extends 15-18 rings from the anal ring compared with 14-24 in S. argus, and 12-16 in S. nigra.

The specific name is from the Latin narinosus (= broadnosed) in reference to the wide and distinctive spatulate shape of the snout.

Stigmatopora narinosa Browne & Smith 2007, Mem. Mus. Vict. 64: 2. Type locality: Edithburg Pool, 35°05'S, 137°45'E, South Australia, depth 2 m.

Bray, D.J. 2021

Atlas of Living Australia