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Flatface Seahorse Hippocampus planifrons Peters, 1877
[CAAB 37 282078]

Distribution Map see an interactive map here (new window)

The Flatface Seahorse, found only in northwestern Australia, was, until recently, thought to be widespread across northern Australia.

Distribution, ecology and habitat:

Endemic to tropical Western Australia, from Broome to Dirk Hartog Island; benthic on algal and rubble reefs in shallow bays from intertidal depths to 20 m.

Size:

Height to 70 mm, but may grow to 120 mm.

Food and feeding:

Carnivores. Like most other seahorses, this species presumably feeds by sucking small crustaceans and other small prey items, including planktonic zooplankton, into its mouth.

Reproduction and early life history:

Reproduction: Sexes separate, reproduction a form of viviparity or ovoviviparity, whereby the males give birth to tiny independent young. The female uses an ovipositor to transfer her eggs into an elaborate enclosed pouch under the abdomen of the male. The male not only fertilizes the eggs inside the pouch and provides physical protection for the developing embryos, he also osmoregulates and aerates the embryos and may provide some nourishment until the offfspring are born.
Eggs: Not described.
Larvae: Not described.

Characteristics:

Meristics: D 23-24 (usually 23); A 4; P 18-19; trunk rings 11; tail rings 37-38; subdorsal rings 3-4 + 1.
Head and body: Head relatively small, snout short, about equal to postorbital length; nasal profile convex, rising upwards to angle of about 45° from snout; trunk slender, more than twice as long as its depth in adults.
Spines and tubercles: Body ridges with small tubercles becoming smooth with age. Subdorsal spines 4/0,0,1,1 or 5/0,0,0,1,1; small outwards curving spine above eye; nape spine small, directed anterodorsally; shoulder ring spines small, uppermost spine low and directed outward next to gill-opening, central spine at level just below level of centre of pectoral-fin base, lowermost spine directed outward; small lateral head spine; small spine behind eye; body spines of small to moderate size along dorsal and lateral ridges, few enlarged, most prominently along dorsal-fin base.
Coronet: Coronet slightly raised, 2 small anterior spines, 3 posterior spines of moderate size, central spine enlarged and recurved.
Lateral line: Lateral line pores small, distinct, situated just above lateral ridge at each ring on trunk, reaching about 18^th tail ring.
Fins: Dorsal-fin origin variable in position, ranging from before, in front of, on, or behind 8^th trunk ring.

Colour:

In life - females overall greenish brown with dark blotching over dorsal region of trunk and tail; snout with dark lateral spots. In preservative - body mainly brown, snout with dark spots.

Similar species:

H. planifrons is similar to H. dahli, differing in having a higher coronet, better developed spines on the trunk and tail ridges, a nape spine directed forwards away from the coronet and spots laterally on the snout.

Fisheries:

There is no known international trade in H. planifrons for the aquarium or Asian Traditional Medicine industries. The species is IUCN listed, however, as a synonym of H. trimaculatus, which is one of the main seahorses involved in the Traditional Medicine trade (see IUCN listing below).

Conservation Status:

International: Listed under Appendix II of the Convention on the International Trade in Endangered Species of Wild Flora and Fauna (CITES). As a result, the species is subject to the Convention, http://www.cites.org/.
Listed (as a synonym of H. trimaculatus) as Vulnerable (VU A4cd) on the 2007 IUCN Red List of Threatened species (see ‘Fisheries' section above). http://www.iucnredlist.org/search/details.php/10087/summ
Australian legislation: Marine Listed under the Federal Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act 1999). http://www.environment.gov.au/epbc/species/marine.html

Remarks:

H. planifrons has been regarded by some authors as a synonym of H. trimaculatus. Specimens from the Northern Territory and Queensland which were previously misidentified as H. planifrons are the Lowcrown Seahorse, H. dahli.

Other common names:

Flat-face Seahorse, Low-crowned Seahorse.

Original citation:

Hippocampus planifrons Peters 1877, Mber. K. Preuss. Akad. Wiss. Berl. 1876: 851, "Naturalists Channel", nw. Australia, 10 fm.

Etymology:

From the Greek ippos = horse and kampe = curvature. The specific name planifrons is from the Latin plan meaning flat or level, and frons meaning brow, forehead or fore part, in reference to the flat face of this species.

References:

Hoese, D.F., D.J. Bray, J.R. Paxton & G.R. Allen. 2006. Fishes. In Beesley, P.L. & A. Wells. (eds.) Zoological catalogue of Australia. Volume 35. ABRS & CSIRO Publishing: Australia, 2178 pp.

Kuiter, R.H. 2000. Seahorses, Pipefishes and their Relatives. TMC Publishing, Chorleywood, UK, 240 pp.

Kuiter, R.H. 2001. Revision of the Australian Seahorse of the genus Hippocampus (Syngnathiformes: Syngnathidae) with descriptions of nine new species. Rec. Aust. Mus. 53: 293-340.

Lourie, S.A., A.C.J. Vincent & H.J. Hall. 1999. Seahorses: an identification guide to the world's species and their conservation. Project Seahorse. London, UK.

Peters, W. 1877. Übersicht der während der von 1874 bis 1876 unter der Commando des Hrn. Capitän z. S. Freiherrn von Schleinitz ausgeführten Reise S. M. S. Gazelle gesammelten und von der Kaiserlichen Admiralität der Königlichen Akademie der Wissenschaften übersandten Fische. Monatsb. Akad. Wiss. Berlin 1876: 831-854.

Pogonoski, J.J., D.A. Pollard & J.R. Paxton. 2002. Conservation Overview and Action Plan for Australian Threatened and Potentially Threatened Marine and Estuarine Fishes, Canberra, Environment Australia, 375 pp.

Whitley, G.P. 1952. Some noteworthy fishes from eastern Australia. Proc. Roy. Soc. N. S. W. 1950/51: 27-32.