P.E. Tompsett, C.J. Neil, & P.A. Gainey

(Polychaetes and Oligochaetes by P.E. Tompsett and C.J. Neil; leeches by P.A. Gainey)

Marine annelids fall into a large and complex phylum, Annelida, the taxonomy of this group is currently under review so the main ‘traditional’ subdivisions are retained in the account below.

Generally, polychaetes have paired, lateral extensions of the body segments known as parapodia, head appendages and several types of chaetae (setae), often in bundles. Chaetae and parapodia give rise to a higher diversity of external morphology in polychaetes than in leeches or oligochaetes. The oligochaetes have fewer, simpler chaetae, rarely in bundles, and lack parapodia or similar structures. The leeches lack parapodia, head appendages and chaetae and have at least one, usually two, terminal suckers. There are no clear ecological boundaries between the groups and all are found in British waters. Polychaetes are almost exclusively marine whilst the oligochaetes have exploited the terrestrial, marine and freshwater environments and, although most leeches are freshwater, there are some 22 or 23 marine species in British seas, all of them parasites of fish.

The systematic sequence and nomenclature followed here is taken from Howson & Picton (1997). The authors would like to acknowledge the invaluable help given by A.S.Y. Mackie, (Amgueddfa Cymru — National Museum Wales), A.I. Muir (The Natural History Museum) and T. Harris (formerly of University of Exeter).

1. Polychaetes ( Bristle Worms)

Polychaetes are widely distributed, often abundant and ecologically important, particularly as a food source for fish and birds. There are some terrestrial and freshwater species but of around 9000 described species worldwide most are marine and of these over 800 have been recorded from British waters. The majority of polychaetes are free-living and they can be found in all marine habitats. They are mostly benthic, but there are a small number of pelagic species. The tiniest live interstitially in spaces in coarse sediments, such as the North Sea species Nerillidium marina which is less than 300μm long. Large species on British coasts include Chaetopterus variopedatus of some 250mm length and the King Rag Nereis virens which can reach 900mm in length. Sedentary or mobile, tube-dwelling or burrowing species live in sediments ranging from rich, organic silts to mobile, coarse sands. Some construct permanent tubes on, or bore into, rocks and shells. Certain species regularly associate with other biota, for example Laminaria holdfasts or other invertebrates. There are commensal and parasitic species, including members of the Myzostomida, a small group historically often considered a separate phylum. Probably the most familiar species are the Lugworms and Ragworms which are dug for use as angling bait.

National distribution data for polychaetes have not yet been assembled and data are relatively scarce. All species listed below have been recorded in fewer than five 10km squares in Cornwall and the Isles of Scilly. The lists have drawn on the few available literature sources and Cornish records for their compilation. They should not be regarded as authoritative. To some extent they reflect recording activity and part of their value will be in prompting more recording. The distribution of some species appears to be affected by temperature zones around the British coast; several are restricted to warmer southern waters.

Conservation concerns for many polychaetes are not known but intertidal populations are threatened locally by pollution such as oil spillages and large-scale disturbance of sediments such as commercial baitdigging. Two polychaetes are listed in Schedule 5 of the Wildlife and Countryside Act, 1981 (amended). One, the Lagoon Sandworm Armandia cirrhosa Filippi, has only been recorded in south Hampshire and is the only RDB polychaete (Bratton, 1991). The other, the Tentacled Lagoon Worm Alkmaria romijni, has been recorded in Cornwall (listed below) and south-west Wales.

The first list below is of species which appear to be rare on Cornish coasts and nationally (pR); this is followed by a list of those with very few local records and which may or may not be nationally scarce. It is hoped that this deficiency of data may encourage a greater recording effort for the future.

Mackie and Erseus (1997) provided the most recent list of British annelids, while Bellan (2001) produced a European register. Helpful references for identification and/or distribution of species include George and Hartmann-Schroder (1985), Hartmann-Schroder (1996), Hayward and Ryland (1990; 1995), Pleijel and Dales (1991), Westheide (1990), Chambers and Muir (1997) and the National Biodiversity Network (NBN) Gateway.

A. Provisionally Rare Species

1.1. Phyllodocida

1.1.1. Polynoidae

Lepidasthenia argus

1.1.2. Phyllodocidae

Eulalia mustela

Phyllodoce longipes

1.1.3. Syllidae

Autolytus longeferiens

Brania clavata

Trypanosyllis zebra

Typosyllis krohni

1.1.4. Lopadorrhynchidae

Pelagobia longicirrata

1.1.5. Nereididae

Neanthes irrorata

1.2. Eunicida

1.2.1. Eunicidae

Eunice vittata

1.2.2. Lumbrineridae

Lumbrineris coccinea

1.2.3. Dorvilleidae

Ophryotrocha hartmanni

1.2.4. Iphitimidae

Iphitime paguri

1.3. Spionida

1.3.1. Spionidae

Polydora giardi

1.4. Capitellida

1.4.1. Maldanidae

Micromaldane ornithochaeta

1.5. Nerillida

1.5.1. Nerillidae

Mesonerilla intermedia

1.6. Polygordiida

1.6.1. Polygordiidae

Polygordius lacteus

1.7. Protodrilida

1.7.1. Saccocirridae

Saccocirrus cf. papillocercus

1.8. Terebellida

1.8.1. Ampharetidae

Alkmaria romijni Tentacled Lagoon Worm

1.9. Sabellida

1.9.1. Sabellidae

Euchone southerni

Myxicola aesthetica

Myxicola infundibulum

Sabella discifera

1.9.2. Serpulidae

Apotamus similis

Vermiliopsis striaticeps

1.9.3. Spirorbidae

Paradexiospira vitrea

Pileolaria berkeleyana

Protolaeospira striata

B. Provisionally Scarce Species (in Cornwall and Isles of Scilly).

1. Phyllodocida

1.1. Aphroditidae

Hermonia hystrix

1.2. Polynoidae

Harmothoe areolata

Harmothoe fraserthomsoni

Malmgrenia marphysae

1.3. Phyllodocidae

Mysta picta

Nereiphylla rubiginosa

Eumida punctifera

1.4. Glyceridae

Glycera fallax

Glycera oxycephala

Glycera tridactyla

1.5. Goniadidae

Goniada norvegica

Goniadella bobretzkii

1.6. Sphaerodoridae

Sphaerodorum gracilis

1.7. Hesionidae

Gyptis rosea

Podarkeopsis capensis

1.8. Syllidae

Autolytus aurantiacus

Autolytus brachycephalus

Autolytus inermis

Autolytus quinquidecimdentatus

Autolytus rubropunctatus

Brania limbata

Ehlersia garciai

Eurysyllis tuberculata

Eusyllis assimilis

Haplosyllis spongicola

Myrianida pinigera

Odontosyllis fulgurans

Odontosyllis polyodonta

Opisthodonta pterochaeta

Pionosyllis compacta

Pionosyllis pulligera

Procerastea haleziana

Sphaerosyllis pirifera

Syllides longocirrata

Trypanosyllis coeliaca

Typosyllis hyalina

Typosyllis variegata

Typosyllis vittata

1.9. Nereididae

Micronereis variegata

1.10. Nephtyidae

Aglaophamus malmgreni

Nephtys hystricis

Nephtys longosetosa

2. Eunicida

2.1. Onuphidae

Aponuphis bilineata

2.2. Eunicidae

Nematonereis unicornis

2.3. Dorvilleidae

Dorvillea (Schistomeringos) rudolphi

3. Orbiniida

3.1. Paraonidae

Aricidea minuta

Paradoneis lyra

Paraonis fulgens

4. Spionida

4.1. Spionidae

Aonides paucibranchiata

Microspio mecznikowianus

Polydora caeca

Polydora caulleryi

Polydora cornuta

Polydora flava

Prionospio banyulensis

Prionospio ehlersi

Prionospio fallax

Prionospio steenstrupi

Pseudopolydora antennata

Pseudopolydora pulchra

Scolelepis bonnieri

4.2. Chaetopteridae

Phyllochaetopterus anglicus

4.3. Cirratulidae

Caulleriella alata

Caulleriella killariensis

Dodecaceria concharum

5. Ctenodrilida

5.1. Ctenodrilidae

Raricirrus beryli

Zeppelina variosetosa

6. Cossurida

6.1. Cossuridae

Cossura longocirrata

7. Capitellida

7.1. Capitellidae

Dasybranchus caducus

7.2. Maldanidae

Clymenura clypeata

Euclymene oerstedii

Heteroclymene robusta

Nicomache trispinata

Proclymene muelleri

8. Opheliida

8.1. Opheliidae

Ophelia limacina

Ophelia rathkei

Ophelia roscoffensis

Polyophthalmus pictus

9. Dinophilida

9.1. Dinophilidae

Dinophilus gyrociliatus

10. Protodrilida

10.1. Protodrilidae

Protodrilus flavocapitatus

11. Oweniida

11.1. Oweniidae

Myriochele danielsseni

Myriochele heeri

Myriochele oculata

12. Terebellida

12.1. Pectinariidae

Petta pusilla

12.2. Sabellariidae

Sabellaria spinulosa

12.3. Ampharetidae

Ampharete falcata

Ampharete lindstroemi

Sosane sulcata

12.4. Trichobranchidae

Trichobranchus glacialis

Trichobranchus roseus

12.5. Terebellidae

Amaena trilobata

Axionice maculata

Loimia medusa

Lysilla loveni

Parathelepus collaris

Polycirrus aurantiacus

Polycirrus caliendrum

Polycirrus tenuisetis

Streblosoma bairdi

Terebella lapidaria

Thelepus setosus

13. Sabellida

13.1. Sabellidae

Chone filicaudata

Euchone rubrotincta

Jasmineira caudata

Sabella variabilis

14. Myzostomida

14.1. Myzostomidae

Myzostomum cirriferum

2. Brackish and Marine Oligochaetes

There are fewer oligochaete species than polychaetes known from the marine environment, but they are often an important part of invertebrate communities in organically-rich, fine sediment habitats. A small number of oligochaete species bridge the gap between fresh and saline water, being found in both, and there is also a small but important group which regularly form the bulk of the macroinvertebrate community on British estuarine mud-flats where they can be found in enormous densities. This group includes sludge worms, a term used to describe species which are commonly identified with organic pollution of marine and freshwater habitats. Aquatic oligochaetes are generally smaller than the terrestrial species and many of the marine species are meiofaunal (less than 1mm in length). Problems with ready identification have undoubtedly deterred the recording of this group so that an assessment of the status and distribution of species is difficult. There are possibly 123 species of oligochaete in British coastal waters (Mackie and Erséus, 1997). These are now classified in just two families which contain brackish and marine species: the Naididae, including the Tubificinae, Rhyacodrilinae, Phallodrilinae and Limnodriloidinae, (see Erseus et al., 2008), and the Enchytraeidae. Within the Naididae, the Naidinae has the fewest marine species - possibly there are only 13 in Britain. The species which is described here as provisionally scarce may be more common than local records suggest.

Paranais litoralis

3. Leeches ( Hirudinea)

14 species of leech have been recorded in Cornwall; of these nine species are marine, of which eight can be considered nationally scarce. Useful references are Llewellyn (1966), Hayward & Ryland (1990) and Leigh-Sharpe (1933).

Branchellion borealis

Branchellion torpedinis

Brumptiana lineata

Hemibdella soleae

Janusion scorpii

Oceanobdella blennii

Oceanobdella microstoma

Pontobdella vosmaeri