Phylum: Annelida Neanthes limnicola Class: Polychaeta, Errantia Order: Phyllodocida, Nereidiformia A mussel worm Family: Nereididae, Nereidinae Taxonomy: Depending on the author, Ne- wider than long, with a longitudinal depression anthes is currently considered a separate or (Fig. 2b). subspecies to the genus Nereis (Hilbig Trunk: Very thick segments that are 1997). Nereis sensu stricto differs from the wider than they are long, gently tapers to pos- genus Neanthes because the latter genus terior (Fig. 1). includes species with spinigerous notosetae Posterior: Pygidium bears two, styli- only. Furthermore, N. limnicola has most form ventrolateral anal cirri that are as long as recently been included in the genus (or sub- last seven segments (Fig. 1) (Hartman 1938). genus) Hediste due to the neuropodial setal Parapodia: The first two setigers are unira- morphology (Sato 1999; Bakken and Wilson mous. All other parapodia are biramous 2005; Tusuji and Sato 2012). However, re- (Nereididae, Blake and Ruff 2007) where both production is markedly different in N. limni- notopodia and neuropodia have acicular lobes cola than other Hediste species (Sato 1999). and each lobe bears 1–3 additional, medial Thus, synonyms of Neanthes limnicola in- and triangular lobes (above and below), called clude Nereis limnicola (which was synony- ligules (Blake and Ruff 2007) (Figs. 1, 5). The mized with Neanthes lighti in 1959 (Smith)), notopodial ligule is always smaller than the Nereis (Neanthes) limnicola, Nereis neuropodial one. The parapodial lobes are (Hediste) limnicola and Hediste limnicola. conical and not leaf-like or globular as in the The predominating name in current local in- family Phyllodocidae. (A parapodium should tertidal guides (e.g. Blake and Ruff 2007) is be removed and viewed at 100x for accurate Neanthes limnicola. identification). Notopodial lobes at posterior end of animal are normal, not elongate, but Description smaller than anterior lobes (Hartman 1938). Size: Individuals 25–45 mm in length, 2.5–4 Setae (chaetae): All setae are composite. mm in width (without parapodia) and have The notopodia (Fig. 5) bears only one kind of 45–82 segments (Hartman 1938). The illus- seta – homogomph spinigers, which are long, trated specimen, from Coos Bay, was 25 sharp composite spines with basal prongs of mm long. equal length (Fig. 4a). The neuropodia (Fig. Color: The illustrated specimen was pale, 5) contain several each of three kinds of setae translucent to pale yellow green. – homogomph and heterogomph spinigers, General Morphology: Very thick worms and heterogomph falcigers (with basal prongs that are rather wide for their length (Fig. 1). of unequal length) (Fig. 4a, b, c). They also Body: Individuals are flattened dorso- have heterogorph and homogomph falcigers ventrally and extremely active. Nereids are with blunt, short and curved setae (Fig. 4c) recognizable by their anterior appendages (Fauchald 1977). N. limnicola has one special including two prostomial palps and four peri- fused falciger in the upper acicular stomial tentacular cirri (see Anterior ap- neuropodium (Figs. 4d, 5) (Johnson 1903). pendages) (Blake and Ruff 2007). (Differentiation among these setae must be Anterior: Prostomium trapezoidal, A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: https://oimb.uoregon.edu/oregon-estuarine-invertebrates and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] Hiebert, T.C. 2015. Neanthes limnicola. In: Oregon Estuarine Invertebrates: Rudys' Illustrated Guide to Common Species, 3rd ed. T.C. Hiebert, B.A. Butler and A.L. Shanks (eds.). University of Oregon Libraries and Oregon Institute of Marine Biology, Charleston, OR. made with a compound microscope after Nephridia: placing the parapodium in glycerin or Possible Misidentifications mounting medium, on a slide.) Acicula or The prostomia of nereid worms are heavy, black spines, are present at the base quite alike, with four eyes, a pair of frontal of each parapodial lobe (Fig. 5). antennae and biarticulate palps, and 3–4 Eyes/Eyespots: Two pairs of eyes in trape- pairs of tentacular cirri. The genus Nean- zoidal arrangement on prostomium (Fig. 2b) thes currently, includes 3–4 local species (Nereididae, Hartman 1968; Blake and Ruff (Blake and Ruff 2007). Neanthes species 2007). The eyes of epitokous individuals have only homogomph spinigerous setae in are enlarged (Hilbig 1997). the posterior notopodia, a trait it shares with Anterior Appendages: One small pair of Hediste, but without the fused falcigers. frontal antennae, which are separated at Some authors currently place N. limnicola in their bases, occurs on the prostomium (Fig. the genus Hediste (Sato 1999; Bakken and 2b). Also on the prostomium are a pair of Wilson 2005; Tusuji and Sato 2012). The palps, with cylindrical processes and small genus Neanthes is further distinguished by hemispherical palpostyles at the distal ends having only conical paragnaths on both pro- (Fig. 2b). Four pairs of tentacular cirri are boscis rings, and biramous parapodia with found on the peristomium. The second of composite setae (Hartman and Reish 1950). dorsal pairs longest (Fig. 2b) (Johnson Neanthes limnicola is distinct because 1903) and the others, including a more ven- individuals are usually pale and translucent, tral pair, are quite short for a nereid. not dark green and its posterior parapodial Branchiae: Absent (Blake and Ruff 2007). lobes are not expanded like those of N. Burrow/Tube: Individuals build thin, pale brandti. brown, loosely constructed tubes in vertical Neanthes brandti has been at times burrows that are Y-shaped and mucus lined considered a subspecies or a synonym of N. (Smith 1950). Newly hatched young build virens, the large (50–50 cm in length), cold- protective tubes of sand grains and mucus. water form (Breton et al. 2004). This latter Pharynx: The pharynx bears a distinct ever- species, however, has only a few sible proboscis. The everted proboscis has paragnaths on its proboscis rings, (i.e. 2–3 two rings, oral (or proximal) and distal (or rows in Areas VII, VIII), not many as in N. maxillary) and terminates with two fang- brandti (4–5 rows in Areas VII, VIII). The shaped jaws (Fig. 3). The oral ring is used prostomium of N. virens is small and largely in burrowing, while the distal ring is triangular, its eyes are small and on the used in feeding (Barnes and Head 1977). posterior half of the prostomium. It has short Each ring is equipped with many papillae antennae and massive palps. These and conical paragnaths and their patterns species exhibit overlapping geographic are taxonomically relevant. In this species distributions and it is possible that they are Area I usually has one tooth; Area II has the the same species (Breton et al. 2004). largest teeth and about 12 in a crescent; Ar- Neanthes succinea is one of the most ea Ill has a broad patch of 20–25; IV has common nereids in the NE Pacific but is rec- broad crescents of 30–35; V usually has no ognizable from N. brandti by its very paragnaths (Hartman 1938); VI has three enlarged posterior notopodial lobes, with a small points and Areas VII and VllI have two small distal dorsal cirrus attached at the end continuous rows (Figs. 3a,b). of the lobe (Blake and Ruff 2007). It has a Genitalia: A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: https://oimb.uoregon.edu/oregon-estuarine-invertebrates and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] heteronereid form and N. limnicola does prefer soft mud, sometimes in channels with not. N. succinea is thought to be a more Salicornia (Smith 1953). However, N. southern form (although it has been repor- limnicola is not limited by substrate and can ted from Netarts Bay). survive in almost entirely dry mud. Thus, this Neanthes species have spinigerous species can survive in unstable environment notosetae only (Hilbig 1997). The morpho- (e.g. Salinas River, Smith 1953). The unique logically similar genus, Nereis sensu reproductive strategy (see Reproduction) of stricto, is characterized by species with N. limnicola may have evolved in response to spinigerous notosetae in the anterior half the unstable or extreme habitats in which they of the body and falcigerous notosetae live (Tosuji et al. 2010). posteriorly (Pettibone 1963; Smith 1959). Salinity: Adapts to a wide range in salinity Common Nereis species include the very from 2–25, but is usually found in areas of re- abundant Nereis vexillosa, an olive green duced salinity (Smith 1950). This species is to brown worm found in many diverse known to inhabit brackish or freshwater (Sato marine environments, especially in mussel 1999; Blake and Ruff 2007) beds. It has greatly elongated, strap-like Temperature: From cool and temperate wa- notopodial lobes in the posterior ters and, although warmth (30°C) negatively parapodia. Nereis eakini, from rocky affects reproduction, it does not cause fatali- habitats, has a long prostomium and ties (Smith 1953). proboscis rings covered with small round Tidal Level: Shallow intertidal. paragnaths. The bright green Nereis Associates: In the Salinas River, associates grubei has greatly expanded posterior include the isopod Gnorimosphaeroma orego- notopodial parapodial lobes and no nensis, and amphipods Corophium paragnaths in Area V of the proboscis. spinicorne, Anisogammarus contervicolus Nereis procera is subtidal in sand, has tiny (Smith 1953). N. limnicola does not overlap eyes, a very long body, and unusually with Nereis vexillosa or Neanthes brandti inconspicuous paragnaths on its proboscis (Coos Bay, 1970 unpublished student report). (Hartman 1968). The genus Nereis differs Abundance: Abundant at Coos bay, espe- from Hediste because members of the cially the east side of Coos Bay (L.C. Ogles- latter genus has 1–3 fused falcigers on the by, pers. com.). Populations are irregularly supra-acicular bunch of posterior distributed and tend to occur in isolation in neuropodial setae (no local species are shallow water in Salinas River, California known, Blake and Ruff 2007).