ORIGINAL ARTICLE On the status of the Hawaiian seahorses Hippocampus hilonis, H. histrix and H. fisheri (Syngnathidae) ZOLTA ´ N SZABO ´ 1 *, BETHANY K. KIMOKEO 1 , ROBERT J. TOONEN 1 & JOHN E. RANDALL 2 1 Hawai‘i Institute of Marine Biology, University of Hawai‘i, Ka ¯ ne‘ohe HI 96744, USA, and 2 Bishop Museum, Honolulu HI 96817-2704, USA Abstract Three species of seahorses of the genus Hippocampus are recognized within the Hawaiian Islands, H. kuda, H. fisheri and H. histrix. Based on molecular and morphological evidence H. kuda is treated here as two subspecies, the Hawaiian H. kuda hilonis and H. kuda kuda from elsewhere in the Indo-Pacific region. Molecular analysis also indicates that recent populations of H. kuda hilonis are not based on introduced fishes as their cytb sequence is identical to that of the H. hilonis holotype. Hippocampus fisheri is endemic to the Hawaiian Islands. The Hawaiian record of H. histrix is based on a specimen collected from O‘ahu in 1877 and one reported from Maui in 1928. The specimens are identified correctly, and there is no reason to doubt these old records, illogical as they seem. Key words: Hawaiian Islands, Hippocampus, meristic and morphological comparison, molecular study, Syngnathidae Introduction Jordan & Evermann (1902) named two new species of seahorses from the Hawaiian Islands in the Bulletin of the US Fish Commission. Hippocampus fisheri Jordan & Evermann, 1902, was adequately described from the holotype, collected at Kailua on the west coast of the island of Hawai‘i, and five specimens from the stomach of a Mahimahi (Cor- yphaena sp.). Hippocampus hilonis Jordan & Ever- mann, 1902, however, was described from only a single specimen from Hilo, Hawai‘i in a mere six lines. The same descriptions were repeated in 1905 for Jordan & Evermann’s The Aquatic Resources of the Hawaiian Islands. Part I.  The Shore Fishes. Both species were then well illustrated. Fowler (1928) placed both H. fisheri and H. hilonis in synonymy of Hippocampus kuda Bleeker, 1852, type locality Singapore, in his Fishes of Oceania. He reported Hippocampus histrix Kaup, 1856, type locality Japan, as a new record for the Hawaiian Islands from a single specimen ‘about 85 mm long, in poor preservation, obtained by C. F. Winslow at Maui.’ Tinker (1944) and Gosline & Brock (1960) followed Fowler in reporting H. kuda and H. histrix from the Hawaiian Islands. Recent major publications on seahorse systematics do not always agree on the taxonomy of various species and species-groups (Lourie et al. 1999, Fricke 2004, Kuiter 2009). Based on Ahnesjo ¨ (2010) and our own results, here we follow Lourie et al. (1999) as the main source for seahorse identification and geographical distribution. Lourie et al. (1999) in- cluded H. fisheri, H. histrix and H. kuda from the Hawaiian Islands in their review of the seahorses of the world. Their distribution map for H. kuda has many Indo-Pacific localities from Pakistan to Tahiti and Hawai‘i. However, they indicated that the name H. kuda ‘may apply to several species.’ Mundy (2005) and Randall (2007) noted that H. histrix is still known from only one small specimen from Maui. They continued in the use of the name H. kuda for the third species of the genus from the Hawaiian Islands. However, Randall added, ‘Cur- rent research may result in the recognition of *Correspondence: Zolta ´n Szabo, Hawai‘i Institute of Marine Biology, University of Hawai‘i, P.O. Box 1346 Ka ¯ne‘ohe, HI 96744, USA. E-mail: zoltan.himb@gmail.com Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark Marine Biology Research, 2011; 7: 701709 (Accepted 14 January 2011; Published online 31 August 2011) ISSN 1745-1000 print/ISSN 1745-1019 online # 2011 Taylor & Francis DOI: 10.1080/17451000.2011.558096 Downloaded by [zoltan szabo] at 00:37 23 September 2011