Halodule bermudensis 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Plantae Tracheophyta Liliopsida Alismatales Cymodoceaceae

Scientific Name: Halodule bermudensis Hartog
Common Name(s):
English Species code: Hr, Species code: Hi
Taxonomic Notes: Originally described as Halodule wrightii,  and re-described as H. bermudensis in 1970. Current status is unclear. Recent collections in Bermuda reveal specimens of Halodule sp. that do not match the type specimen for Halodule bermudensis, and have been identified as H. wrightii. The status of Halodule bermudensis is therefore unknown, and  it is in need of genetic review to determine if it is a distinct species and requires more research to find this morphotype in Bermuda.

Assessment Information [top]

Red List Category & Criteria: Data Deficient ver 3.1
Year Published: 2010
Date Assessed: 2009-03-21
Assessor(s): Coates, K., Manuel, S., Sarkis, S., Kenworthy, J., Carruthers, T.J.B., Short, F.T. & van Tussenbroek, B.
Reviewer(s): Livingstone, S., Harwell, H. & Carpenter, K.E.
Halodule bermudensis is endemic to Bermuda in the Atlantic Ocean. The only confirmed records of collections of this morphological form of the genus are from 1922 in Walsingham Bay and 1913 in Gibbet Island. The specific distinctness of this taxon is questioned, based on current criteria for distinguishing among species of the genus Halodule (leaf morphology). Unless more specimens are located, its genetic characters may be difficult determine from the remaining preserved type specimens. Existing genetic data for Halodule specimens from Bermuda do not match the original morphological type that was described as H. bermudensis.

Halodule bermudensis is listed as Data Deficient due to the currently undetermined taxonomic status ( i.e. whether the species is a distinct from H. wrightii). However, it is very important to determine the validity of this species since its extremely limited range in Bermuda would qualify it for a threatened category if found to be valid. It could possibly be extinct in fact as no recent specimens matching the original description have been found in recent years.It is highly recommended that more surveys are carried out, and that both genetic and morphological evidence, particularly developmental flowering structure, be used to determine its taxonomic and conservation status.

Geographic Range [top]

Range Description:Halodule bermudensis is endemic to Bermuda in the Atlantic Ocean. The species was originally collected from Walsingham Bay and Gibbet Island, Flatts, Bermuda. The only confirmed records of collections of this morphological form of the genus are from 1922 in Jespersen, Walsingham Bay and 1913 in Collins, Gibbet Island (den Hartog 1964). However, no plants fitting the original taxonomic description have been found recently in Bermuda (K. Coates pers. comm. 2009).
Countries occurrence:
FAO Marine Fishing Areas:
Atlantic – western central
Additional data:
Estimated area of occupancy (AOO) - km2:1
Lower depth limit (metres):2
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:There is no specific population information available for Halodule bermudensis, and recent investigations suggest that the morphological type on which the description was based no longer is found in Bermuda (K. Coates pers. comm. 2009). Halodule bermudensis was only ever recorded from two sites.

It may still exist in the southwest corner of Bermuda (S. Manuel and K. Coates unpublished data). The total population covers an area of less than 50 m², and if the grass at that site turns out not to be H. bermudensis (based on morphology), then the last known records of this species may be from 1922 collections (K. Coates pers. comm. 2009).
Current Population Trend:Decreasing
Additional data:
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:Halodule bermudensis has only been identified from two very shallow subtidal locations, both where the seagrass is exposed at extreme low tides. It is not certain what the conditions in Walsingham Bay were in 1922, but it is now a shallow, very sheltered bay with mangroves and shoreline outflows from alkaline ponds. Also, as it is low energy, the sediments tend to be fine and soft. The second location, Gibbet Island, in much more exposed and the sediments are sandy - quite different from Walsingham Bay.

No reproductive plants from Halodule bermudensis have ever been seen.
Generation Length (years):2

Threats [top]

Major Threat(s): Pollution, boating and shoreline development are the threats present in the area (K. Coates pers. comm. 2009). Coastal development for moorings and docks are also potential threats (S. Sarkis pers. comm. 2007).

Conservation Actions [top]

Conservation Actions: There are no species-specific conservation measures currently in place.  A marine park was created in an area very close to the type location of H. bermudensis, however, probably because of the complex taxonomic history of this species, its presence in Walsingham Bay was not taken into account when the park boundaries were finalized and Walsingham Bay is not actually included in the marine park. A seagrass management plan is currently being developed (S. Sarkis pers. comm. 2007, S. Manuel and K. Coates pers. comm. 2009).

More research is needed regarding the taxonomy, distribution, life history and ecology of this species.  Populations trends should be monitored.

Citation: Coates, K., Manuel, S., Sarkis, S., Kenworthy, J., Carruthers, T.J.B., Short, F.T. & van Tussenbroek, B. 2010. Halodule bermudensis. The IUCN Red List of Threatened Species 2010: e.T173374A7002336. . Downloaded on 26 September 2018.
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