The four recognized inshore species of seahorse from Southern Australasia, and one new type can be keyed out using the table below.  One species we have tabled was described and previously named, New Holland Seahorse Hippocampus novae-hollandiae.  Its status as a species was withdrawn after a revision that considered the species as synonymous with H. whitei.  However, the specimens named as Hippocampus novae-hollandiae did not conform to H. whitei.  This misnaming was not recognised until 2006 after the mass strandings of seahorses on Southern Yorke Peninsula, South Australia. The Bull-neck Seahorse is a deeper water species from 64 to 100 meters depth. 

Mass standings of seahorses in 2006 and the previous discredited species H. novae-hollandiae.

In 2006 the IFG became aware because of information from IFG participant Adrian Brown of the mass stranding of seahorses during April 2006 on southern York Peninsula, South Australia.  Upon examination by Dr Robert Browne these seahorses were unfamiliar and conformed to the same type as many specimens named Hippocampus novae-hollandiae in the collection of the South Australian Museum.   However, in the past specimens in the South Australian Museum that did not conform to H. abdominalis or H. breviceps were considered as Hippocampus novae-hollandiae.

After the revision these specimens were then considered as H. whitei.  They are very different from H. whitei as shown in the meristics table.  Consequently the status of this type is being revised in comparison to other seahorses of Southern Australasia.  The IFG has given the common name Willyama Seahorse to this new type in recognition of the site of the mass strandings which is characterised by the wreck of the Willyama.  The Willyama was stranded in April 1907 almost exactly 100 years previous to the strandings of the Willyama Seahorse.

1980, Scott et al; White’s Seahorse. H. whitei, Bleeker, Verh. Kon. Akad. Wetensch. Amsterdam, 2 (17), 1855, p. 311.  

1923, Waite; Common Seahorse. Hippocampus novae-hollandiae. Species occurs through southern Australia from Western Australia to New South Wales, also in Tasmania. 

1921, Waite and Hale; H. novae-hollandiae, Stein., Sitzb. Akad. Wiss. 1iii. 1866. p. 474, pl. 1, fig. 2.

RDF = Rings supporting Dorsal Fin.  As used by Project Seahorse 2004 this index is expressed the number of rings covered by the dorsal fin with the number of body rings then the number of tail rings. ie. 3/1 means three body rings and one tail ring.  Project Seahorse illustrations in their ‘Species Descriptions’ frequently show dorsal fins extending between rings.  With other syngnathids the distance between the rings - as 0.25 of the distance covered by the dorsal fins - are also expressed (Dawson 1984). We have adopted Dawson 1984 conventions in Inshore Fish Group (IFG) studies.  This system is different than that used for pipefish.

TDR = total dorsal ring distance covered by the dorsal fin.

TR = The number of Trunk Rings.

Coronet = the crown at the back of the head; expressed by project seahorse a single number.  IFG has found the spines on the coronet often array as a polygon with a central spine.  The Inshore Fish Group uses the convention of the central spine then the number of spines in the polygon. ie. 1/4 means a central spine surrounded by four spines.

Dors. Rays = The number  of Dorsal Fin Rays.

Pect. Rays = The number of Pectoral Fin Rays.

Height = distance from the tip of the coronet to the tip of the uncurled tail.

Cheek spine = on the bottom of the operculum on the side of the head.