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Investigations of the Black Lugworm (Arenicola defodiens) in South Wales
... In describing the gills and nephridiopores, Wells did not state how useful he felt them to be as characters. In the two species Arenicola marina and Arenicola defodiens, that are sympatric in the UK, the gills have been shown to be useful characters in respect to the branching pattern (Cadman & Nelson-Smith, 1993;Brind & Darbyshire, 2015). However, in the Abarenicola species investigated here, the branching pattern and number of main gill stems do not show significant differences. ...
The new species Abarenicola wellsi n. sp. from the Falkland Islands is described along with a re-description of Abarenicola brevior n. stat. with which it had previously been confused. The two species are distinguished using both morphological and molecular techniques, new characters are described and previously recognized characters are clarified, all of which support the assignment of species status as opposed to subspecies. Both species are part of the Abarenicola assimilis ‘group’ within which all taxa were originally described as subspecies. The group as a whole is re-evaluated and all members are elevated from subspecies to species status based mainly on the new characters of shape, distribution and pigmentation of the proboscidial papillae. The group now consists of six species: Abarenicola assimilis n. stat., A. brevior n. stat., Abarenicola devia n. stat., Abarenicola haswelli n. stat., Abarenicola insularum n. stat. and A. wellsi n. sp.
A new species of lugworm Arenicola defodiens sp. nov. (common name ‘black lug’ or ‘runnydown’) is described from 148 specimens taken from intertidal sands around South Wales. Comparisons are made with the well-known and generally more common lugworm Arenicola marina (L.). To aid in diagnosis, a table illustrating differences in the genetics, ecology and morphology is also provided.
This study demonstrates that the two species of lugworm, previously classified as Arenicola marina occupy distinct zones within sandy beaches around South Wales. Arenicola marina (sensu stricto) or blow lug, is found higher up the shore, tending to be concentrated at mid-tide level, whilst A. defodiens Cadman & Nelson-smith, 1993 or black lug is most numerous at or below mean low water of spring tides and, unlike A. marina in this area, also apparently extends subtidally. Arenicola marina is found in estuaries, unlike A. defodiens, and seems to inhabit slightly less exposed beaches. Degree of sorting, mean and median particle size do not appear to be a significant factor in determining lugworm distributions. Some possible explanations for these observed differences, including differences in burrow depth and salinity tolerance, are discussed.