Atractophora is a small red alga, mucilaginous in nature and grows as an epiphyte on maerl. It is known only from a few isolated sites in the British and Ireland.

In brief

• This species grows as an epiphyte on maerl.
• It has been found at only four localities in Northern Ireland.
• It grows in the shallow sublittoral to 20 m.
• The best time to see it is probably July to September.
• It is rare in Britain and Ireland, being only of western distribution.
• No threats are known save damage to the habitat.

Species description: Only the gametangial phase of the plant is known, tetransporangia are unknown. The gametangial thallus is erect, red and grows to a height of 10 cm. It is attached by a small basal disc and is much branched with downgrowing filaments which enclose the axes. The spreading filaments grow irregularly in a diffuse manner. It grows as an epiphyte on maerl.

Life cycle: The carpospores germinate and develop directly to the gametangial phase. A tetrasporangial phase is unknown.

Similar species: Many other finely-branched algae are similar such as: Antithamnion, Dasya and Spyridia. Microscopic examination is required for identification.

How to see this species: There are only four records from Northern Ireland: County Antrim, from Rathlin Island and Loughan Bay and in County Down, at Greenore Point and near the entrance of Strangford Lough. The species is to be found only in the sublittoral to 20 m depth and is best looked for by SCUBA diving over maerl beds.

Current status: Rare. Probably under-recorded. It is recorded from only four sites in Northern Ireland: Rathlin Island and Ballygalley Head in County Antrim and a southern shore of Strangford Lough and Greenore Point in County Down. This is mainly a western species with records from the Inner Hebrides of Scotland, Galway and Cork in the south of Ireland, a few records from Wales and south-western England.

Why is this species a priority in Northern Ireland?

• Criterion 3: Rare or restricted range – rare breeding species confined to 5 hectads or less (based on expert judgement).

Threats: As far as is known, there is no threat and no note of any decline aside from. the loss of preferred habitat (maerl). Any damage to the sublittoral will endanger this species and others.

Action: Records of new sites for this species, with details of habitat and population are always valuable. Observations with a photograph can be recorded using iNaturalist, find the MBDP-NI iNaturalist project here.

Alternatively, records can be sent to CEDaR, National Museums Northern Ireland, 153 Bangor Road, Cultra, Holywood, County Down, BT18 0EU. Tel 028 9039 5257, e-mail cedar.records@nationalmuseumsni.org, or via the online portal.

Objectives:

• The status of Atractophora hypnoides will be surveyed and monitored and appropriate conservation action undertaken if required.

Conservation:

• Rathlin Island is a Marine Protected Area with multiple designations.
• Strangford Lough is a Marine Protected Area with multiple designations.

Distribution Map from NBN: Atractophora hypnoides at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Atractophora hypnoides at iNaturalist World Species Observations database.

WoRMS: Atractophora hypnoides at World Register of Marine Species. Accepted name: Atractophora hypnoides P.Crouan & H.Crouan, 1848. AphiaID: 145767.

Classification: Biota; Plantae; Biliphyta; Rhodophyta; Eurhodophytina; Florideophyceae; Rhodymeniophycidae; Atractophorales; Atractophoraceae; Atractophora

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Adapted from text by Osborne Morton (2026). Atractophora hypnoides. P.Crouan & H.Crouan, 1848. [In] Priority species, Marine Biodiversity Portal NI. https://www2.habitas.org.uk/marbiop-ni/priorityaccounts.php?item=ZM1910. Accessed on 2026-09-13