Eunereis patagonica (McIntosh, 1885)

Darbyshire, Teresa, 2014, Intertidal and nearshore Nereididae (Annelida) of the Falkland Islands, southwestern Atlantic, including a new species of Gymnonereis, ZooKeys 427, pp. 75-108 : 83-86

Taxon classification Animalia Phyllodocida Nereididae

Eunereis patagonica (McIntosh, 1885) Figure 3

Nereis patagonica McIntosh, 1885: 228-229, Pl. XXXV, figs 13-15, Pl. XVIIA, figs 1-2. - Pratt 1898: 15.

Nereis (Eunereis) hardyi Monro, 1930: 109-111, fig. 39. - Monro 1936: 134-135.

Eunereis patagonica . - Hartman 1953: 29. - Hartman 1964: 97, Pl. XXX, figs 3-4. - Hartman 1967: 62-64, Pl. 15.

Material examined.

Strait of Magellan, stn 313 (52°20'S, 067°39'W), sand, 100.6 m, 2 syntypes (NHMUK 1885.12.1.171) 20.01.1876; South America, off Uruguay, stn 1 (33°00'S, 051°10'W), blackish clay, 80 m, 2 specimens (SMNH 37888), 12.12.1901; south of West Falkland, Burdwood Bank, stn 59 (53°45'S, 061°10'W), gravel & stones, 137-150 m, 13 specimens (9-SMNH 37894; 4-SMNH 37902), 12.09.1902; off Falkland Islands, stn WS 86 (53°53'30"S, 060°34'30"W), 6 syntypes Nereis (Eunereis) hardyi (NHMUK 1930.10.8.841-844), 03.04.1927; Strait of Magellan, stn WS 834 (52°57'45"S, 068°08'15"W), 4 specimens Nereis (Eunereis) hardyi (NHMUK 1936.2.8.1463-1476), 02.02.1932.

Description.

Length up to 130 mm, width to 5 mm (excluding parapodia) for up to 85 chaetigers. Eyes present (Fig. 3 A–B). Tentacular cirri reaching to chaetiger 6-8 (postero-dorsal pair). Paragnaths absent from maxillary ring; arranged on oral ring as follows (Fig. 3 B–C): Area V =1-2; Area VI = 0; Areas VII–VIII = 7-8 in a row. Jaws dark, 5-10 teeth.

Dorsal cirrus longer than notopodia throughout (Fig. 3D), becoming more pronounced posteriorly. Anterior notopodia with dorsal and median ligules conical, median slightly more stout than dorsal. Small, notopodial prechaetal lobe present in anterior chaetigers.

Neuropodia with postchaetal lobe and ventral ligule equal-sized anteriorly; postchaetal lobe conical, reducing in size posteriorly, ventral ligule rounded in the anterior, conical posteriorly.

Notopodia with homogomph spinigers throughout, falcigers absent. Neuropodia with homogomph spinigers and heterogomph falcigers in superior fascicle, inferior fascicle with heterogomph spiniger and falcigers.

Species builds tough-walled tubes coated in sand grains and other coarse particles.

Remarks.

The above description is based on McIntosh (1885), Monro (1930, 1936 as Nereis hardyi ), and Hartman (1953, 1967). However, there is some discrepancy between the original descriptions that can now be clarified following examination of the specimens from those accounts. All three authors agree that paragnaths are absent in Areas I and II and that Area VII–VIII has a single row of 7-8. In Area III, paragnaths are absent on the specimens of both Monro (1930, 1936) and Hartman (1953, 1967), however there is a single conical paragnath present on McIntosh’s specimen. Paragnaths are absent from Area IV on specimens of McIntosh and Monro as well as Hartman’s (1953) Falkland Island specimens (SMNH 37894, 37902) but 3 conical paragnaths are present on her Uruguay specimens (SMNH 37888). The paragnaths described for Area V in Monro (1930, 1936) are present in identical form on Hartman’s (1953) Falkland Island specimens, although she placed them in Area VI in her description, however her Uruguay specimens from the same survey have 3 conical paragnaths in the same position. A single paragnath is present in Area V of McIntosh’s specimen and it is assumed that the second paragnath has been lost or is absent through aberration as McIntosh states in his description that the single paragnath is "nearly, but not quite median".

It is clear that Hartman’s (1953) Uruguay specimens are a different, currently unidentified species but that her Falkland Island specimens are identical to those of Monro (1930, 1936). Hartman’s 1967 description also agrees with Monro’s and the modified description above reflects these specimens. The presence of the single paragnath in Area III of McIntosh’s specimen requires further investigation as to whether this means that the species needs future re-assessment, as this would place the species in a different genus. Unfortunately, the specimen is in poor condition and a second, smaller specimen from the same location is even worse. However, a comparison of parapodia and what chaetae are available (the vast majority are broken on the McIntosh specimens) show them to be comparable. The paragnath arrangement above is therefore based on the specimens of Monro (1930, 1936) and Hartman (1953, 1967) that were actually collected from the Falkland Islands. The designation of McIntosh’s specimen requires further investigation although as it only deviates from the others in the presence of that single paragnath in Area III it is possible it is aberrant.

Eunereis patagonica was first recorded from the Falkland Islands by Pratt (1898) from samples that were probably from intertidal or shallow water samples, however no actual habitat, depth or locality details were given. The only other records from the Falkland Islands are those of Monro (as Nereis hardyi : 1930, 1936) and Hartman (1953, 1967) from offshore (106-150 m) samples, as well as an even deeper record at 1879-1886 m by Hartman (1967).

Outside of the region, the species was recorded by Hartman (1967) from 31 m (Cape Horn) to 300 m (South Shetland Islands) together with an additional record of a pelagic epitoke from the Pacific Antarctic Ridge at 3660 m considered to have been carried beyond its viable range.

The species is here believed unlikely to be found intertidally around the Falkland Islands but with potential to be found in the region’s nearshore (<30 m) waters; Pratt’s 1898 record (if accurate), likely being from this region.

Habitat.

Sand, shell, stones; 31-1886 m (?3660 m)

Distribution.

Tierra del Fuego, Strait of Magellan, Cape Horn, Falkland Islands, South Shetland Islands, South Orkney Islands,?Pacific Antarctic Ridge