Acentronura australe 

Scope: Global

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Actinopterygii Syngnathiformes Syngnathidae

Scientific Name: Acentronura australe
Species Authority: Waite & Hale, 1921
Common Name(s):
English Southern Little Pipehorse, Southern Pygmy Pipehorse
Idiotropiscis australe (Waite & Hale, 1921)
Taxonomic Source(s): Dawson C.E. 1984. A new pipehorse (Syngnathidae) from Western Australia, with remarks on the subgenera of Acentronura. Japanese Journal of Ichthyology 31(2): 156–160.
Taxonomic Notes: Dawson (1984) and most later authors consider Idiotropiscus to be a subgenus of Acentronura.

Assessment Information [top]

Red List Category & Criteria: Data Deficient ver 3.1
Year Published: 2016
Date Assessed: 2006-02-02
Assessor(s): Kendrick, A.J. & Morgan, S.K.
Reviewer(s): Martin-Smith, K. & Morgan, S.K.
This species is currently known from very few specimens, and more research is needed on all aspects of its ecology, life history, reproduction, and distribution. The only quantitative estimates of abundance found the species at very low density (2.5–12.5x10-5 ind m-2), even relative to other syngnathids (see Habitat and Ecology). These surveys may or may not have been carried out in favourable habitat for A. australe. Similar syngnathids are known to inhabit reef and/or soft-bottom habitats where they are well camouflaged against algae or seagrass (Kuiter 2000, Kuiter 2004).

Acentronura (Idiotropiscis) australe is a male pouch brooder and, like some other syngnathid species, may have a low reproductive rate compared to other teleosts (Foster and Vincent 2004). This is supported by the fact that two male specimens collected near Carnac Island carried broods of 10 and 80 eggs (Kendrick, unpublished data). It is not known how widely the young of A. australe disperse, nor whether this brooding species may be particularly susceptible to localized extinction.
Previously published Red List assessments:

Geographic Range [top]

Range Description:Currently known only from few (i.e., <10) specimens collected from several localities in southern Australian marine waters. Records exist from Cape Jervis and St Vincent’s Gulf in South Australia, and in the vicinity of Carnac Island in south-western Western Australia.

See the Supplementary Material for a map of the known range of A. australe.
Countries occurrence:
Australia (South Australia, Western Australia)
FAO Marine Fishing Areas:
Indian Ocean – eastern
Additional data:
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:The current limited knowledge of the species suggests that it naturally occurs in low abundances in specific habitats. The distribution, size, connectivity and number of populations remain unknown.
Current Population Trend:Unknown
Additional data:

Habitat and Ecology [top]

Habitat and Ecology:Acentronura australe, is thought to camouflage itself against algae and seagrass, like many of its closest relatives (Kuiter 2000). Surveys in the vicinity of Carnac Island in Western Australia found that the abundance of this species was qualitatively low, and near Freemantle WA, Kendrick and Hyndes (2003) found densities of ca. 1.25x10-4 individuals m-2 on unvegetated bottom, and densities of 2.5x10-5 individuals m-2 in the overall survey area that was largely dominated by seagrasses. These densities are very low, even relative to other syngnathids. In the same study area, densities of another prevalent syngnathid, S. nigra, ranged from 1.3–15 individuals per m² in the various seagrass habitats surveyed (Kendrick and Hyndes 2003). Other syngnathids such as seahorses are known to be rare, but are still found at densities 1–5 orders of magnitude greater than A. australe (from 0.006–1.1 individuals per m² (Foster and Vincent 2004)). With the exception that it is known to be a pouch brooder, nothing is known of the reproductive biology or diet of A. australe.

A similar species from eastern Australia, Acentronura lumnitzeri (Syndney’s Pygmy Pipehorse), is known to occupy semi-exposed rocky reefs from 6–30 m, sparsely covered with clumps of Rhodophytes which provide good camouflage for the species (Kuiter 2004). Individual animals have been observed to occupy the same small sections of reef for up to eight months at a time (Kuiter 2004), suggesting that A. lumnitzeri, and perhaps also A. australe, may be site faithful.

Threats [top]

Major Threat(s): Not known to be fished. The only known Western Australian locality of A. australe, in the vicinity of Carnac Island, is adjacent to a major coastal residential and industrial area, which includes heavy port and naval infrastructure. Coastal waters in this area are currently subject to channel dredging and marine shell-sand mining, while marine pollution represents a significant potential threat.

Conservation Actions [top]

Conservation Actions: 1. No legislation has been enacted to specifically protect this species.
2. No Australian Society for Fish Biology listing.
3. This species may occur in the Marmion and Shoalwater Islands Marine Parks, which are located some kilometers from Carnac Island in Western Australia.

Citation: Kendrick, A.J. & Morgan, S.K. 2016. Acentronura australe. The IUCN Red List of Threatened Species 2016: e.T61314A91708447. . Downloaded on 21 October 2016.
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