Hippocampus nalu Short, Claassens, Smith, de Brauwer, Hamilton, Stat & Harasti, 2020
Sodwana pygmy seahorse

Family:  Syngnathidae (Pipefishes and seahorses), subfamily: Syngnathinae
Max. size:  2.2 cm SL (male/unsexed); 1.89 cm SL (female)
Environment:  demersal; marine; depth range 12 - 17 m
Distribution:  Western Indian Ocean: South Africa. Probably occurring further north off East Africa in Mozambique, Tanzania, and Kenya, and offshore to Madagascar which may be confirmed by future localised ichthyofaunal surveys.
Diagnosis:  Dorsal soft rays (total): 12-12. This species is distinguished by the following set of characters: tail rings 29-30; D 12; pectoral fin rays 10; subdorsal rings 4; there are 2 pairs of bilateral wing-like protrusions behind the head formed by a pair of large oblong spines projecting anterolaterad on the first superior trunk ridge and 1 pair of unique double cuspidate spines projecting anteriad on the second superior trunk ridge; double spine above the eyes; no spines at the sixth superior trunk and eighth inferior trunk ridges; superior trunk ridge ending with two subdorsal spines protruding laterad; posteriormost spine greatly enlarged on twelfth trunk ridge (Ref. 122372).
Biology:  This species remains undetected because of its cryptic behaviour and diminutive size. It is observed in flat sandstone-based coral reefs comprising of low pinnacles, shallow drop offs, and sandy gullies, with the latter being exposed to strong currents. It was found loosely associating with short algal turf, used as a holdfast, which was growing on sand-covered coral bedrock separated by sandy gullies (around 2 meters wide). Ambient seawater temperature averaged ca. 24 °C during the dives, which were conducted in October of 2018. Collectors experienced strong swells on the exposed reefs of 2 Mile Reef during data collection. The holotype and paratype appeared to be a mated pair, found within approximately 60 cm distance of each other on the two dives. Behaviour of the pair was observed prior to collection which was very similar to congeners H. pontohi and H. japapigu. Several individuals, including a small juvenile (ca. 1.0 cm SL), were found in the gullies and observed to be associated with low-growth algal turf. The juvenile, retained the dark colouration of a recently settled juvenile pygmy seahorse (Ref. 122372).
IUCN Red List Status: Not Evaluated (N.E.) Ref. (130435)
Threat to humans:  harmless
Country info:   
 


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