Wednesday, May 20, 2020

[Ichthyology • 2020] Hippocampus nalu • A New Species of Pygmy Seahorse (Teleostei, Syngnathidae) from South Africa, and the First Record of A Pygmy Seahorse from the Indian Ocean

Hippocampus nalu 
Short, Claassens, Smith, Brauwer, Hamilton, Stat & Harasti, 2020

 DOI: 10.3897/zookeys.934.50924
  (photograph Richard Smith /

A new species and the first confirmed record of a true pygmy seahorse from Africa, Hippocampus nalu sp. nov., is herein described on the basis of two specimens, 18.9–22 mm SL, collected from flat sandy coral reef at 14–17 meters depth from Sodwana Bay, South Africa. The new taxon shares morphological synapomorphies with the previously described central Indo-Pacific pygmy seahorses, H. colemani, H. japapigu, H. pontohi, and H. satomiae, and H. waleananus, including diminutive size, twelve trunk rings, prominent cleithral ring and supracleithrum, spines on the fifth and twelfth superior and lateral trunk ridges, respectively, and prominent wing-like protrusions present on the first and/or second superior trunk rings posterior to the head. Hippocampus nalu sp. nov. is primarily distinguished from its pygmy seahorse congeners by highly distinct spine morphology along the anterior segments of the superior trunk ridge. Comparative molecular analysis reveals that the new species demonstrates significant genetic divergence in the mitochondrial COI gene from the morphologically similar H. japapigu and H. pontohi (estimated uncorrected p-distances of 16.3% and 15.2%, respectively). Hippocampus nalu sp. nov. represents the eighth member of the pygmy seahorse clade to be described from the Indo-Pacific, the first confirmed record from the African continent and the Indian Ocean, and an extension of more than 8000 km beyond the previously known range of pygmy seahorses from the Central and Western Indo-Pacific.

Keywords: Africa, COI, cryptobenthic, ichthyology, marine fish, morphology, Sodwana Bay, taxonomy

Figure 5. Hippocampus nalu in situ, SAMC-F041933, holotype, female, Sodwana Bay, South Africa at 14 m depth
(photograph Richard Smith / 

Figure 6. Hippocampus nalu in situ, SAMC-F041934, paratype, male, Sodwana Bay, South Africa at 14 m depth
(photograph Richard Smith /

Hippocampus nalu sp. nov.

Diagnosis: Hippocampus nalu sp. nov. is diagnosed by the following combination of characters: tail rings 29–30; dorsal fin rays twelve; pectoral fin rays ten; subdorsal rings four; two 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 a pair of unique double cuspidate spines projecting anteriad on the second superior trunk ridge; double spine above the eyes; absence of spines at the sixth superior trunk and eighth inferior trunk ridges; superior trunk ridge ending with two subdorsal spines protruding laterad; the posteriormost spine greatly enlarged on twelfth trunk ridge.

Etymology: Named after Savannah Nalu Olivier who discovered the new species in Sodwana Bay. In the South African languages, Xhosa and Zulu, nalu refers to the expression ‘here it is’ and therefore we extend its meaning in this case to the simple fact that H. nalu was there all along until its discovery. Additionally, the species name nalu is also the Hawaiian word that refers to the waves or surf of the moana (ocean), for that reason we find the name relevant as H. nalu was observed moving about in strong surge to different locations in the sandy habitat. A noun in the genitive.

New English Names: Sodwana pygmy seahorse, African pygmy seahorse, and Honeypot seahorse are proposed here for Hippocampus nalu.

Figure 7. Hippocampus nalu in situ, juvenile, approximately 10 mm SL, Sodwana Bay, South Africa at 14 m depth 
(photograph Richard Smith / 

Figure 8. Distribution of Hippocampus nalu. Type locality in red.

 Graham Short, Louw Claassens, Richard Smith, Maarten De Brauwer, Healy Hamilton, Michael Stat and David Harasti. 2020. Hippocampus nalu, A New Species of Pygmy Seahorse from South Africa, and the First Record of A Pygmy Seahorse from the Indian Ocean (Teleostei, Syngnathidae). ZooKeys. 934: 141-156. DOI: 10.3897/zookeys.934.50924