Nephtys Caecoides Class: Polychaeta, Errantia
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Phylum: Annelida Nephtys caecoides Class: Polychaeta, Errantia Order: Phyllodocida, Phyllodocida incertae sedis A sand worm Family: Nephtyidae Description inserted just beneath dorsal cirri, which are Size: Individuals up to 100 mm in length and small, in anterior setigers (Blake and Ruff 5–8 mm in width, with up to 129 segments 2007) (Fig. 5). Beginning with the fourth seti- (Hartman 1968; Hilbig 1997). The illustrated ger, and continuing to within 10–20 setigers specimen has 115 segments (Fig. 1). from worm posterior, there is a recurved cirrus Color: A strong pigment pattern on prosto- between the parapodial lobes (Fig. 5) (Lovell mium and first few segments (Fig. 2) per- 1997). In juvenile specimens, this can be sists through preservation. Body usually nearly straight (Fauchald 1977). steel to dark grey (Hartman 1938). The interramal cirrus is larger than the General Morphology: Anterior cylindrical in dorsal cirrus, except in the last nine segments cross-section and becomes slender and rec- (Hartman 1968). tangular posteriorly (Nephtyidae, Blake and Setae (chaetae): All nephtyid setae are sim- Ruff 2007). ple and the setae of both rami are of similar Body: Trim, stiff and slender in appearance morphology. Overall, there are four main (Hartman 1938), rectangular in cross section types of nephtyid setae including capillary (Hartman and Reish 1950). Anterior third is (e.g. spinose), barred (which are pre- stout and wide, while the middle and poste- acicular), lyrate and setae with spines rior regions become slender and more flexi- (Dnestrovskaya and Jirkov 2011). Nephtys ble (Hilbig 1997). First segment is incomple- caecoides exhibits three setal types; 1) a te dorsally (Hartman 1968) (Fig. 2). bunch of short, stiff and slender barred setae Anterior: Prostomium is trapezoidal (pre-acicular) (Fig. 4a, b); 2) post-acicular se- or rounded and changes shape when pro- tae with upper fascicle of spinulose capillaries boscis is everted (Fig. 2) (Hilbig 1997). and large middle fascicle with wide spinose Trunk: Thick with widely separated setae (Fig. 4c); 3) neurosetae with upper parapodial rami (Fig. 1, 5). smooth capillaries and spinose setae in midd- Posterior: Pygidium bears long cau- le fascicle and spinulose capillaries in lower dal cirrus that is sometimes lost during col- fascicle. Setae of first parapodium are poin- lection or preservation. ted anteriorly and the remainder are lateral Parapodia: Parapodia are biramous and (Fig. 2) (Hilbig 1997). A single acicula is pre- rami are widely separated, densely packed sent in each ramus, and is transparent or ye- and their setae are fan-shaped (Nephtyidae, llow and tapers to a fine tip (Hilbig 1997). Blake and Ruff 2007). Both noto- and neu- Eyes/Eyespots: Absent in adults (Hilbig ropodia are rounded in the worm posterior 1997). (Fig. 5b) and the acicular lobes are incised Anterior Appendages: Prostomium bears in the middle of the worm (Fig. 5a). First pa- four small simple antennae, in two pairs which rapodial pair pointed anterior (Hilbig 1997). are widely separated. One pair of nuchal or- Another defining characteristic of the gans present (Hilbig 1997). Nephtyidae are the interramal cirri that are Branchiae: The interramal cirri, which are in- 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. Nephytes caecoides. 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. serted just beneath each dorsal cirrus, are phological details. The species most closely sometimes called branchiae (Blake and Ruff related to and difficult to differentiate from N. 2007). caecoides include N. caeca and N. cali- Burrow/Tube: forniensis. N. caeca is slightly larger, irides- Pharynx: Bears short and wide proboscis cent, with no prostomial pigmentation and a with a variety of papillae, their number and rough proboscis with no unpaired medial arrangement is of taxonomic significance papilla. Furthermore, this species has inter- (Blake and Ruff 2007). The proboscis in ramal cirri beginning on the fifth or sixth se- Nephtys species can be divided into three tiger, not the fourth (as in N. caecoides). distinct regions including the proximal, sub- This is a northern species, which is locally distal and distal (Lovell 1997) (Fig. 3). In N. rare, and likely introduced from the eastern caecoides there are 20 pairs of distal papil- United States (Blake and Ruff 2007). N. lae, an unpaired mid-dorsal papilla and 22 californiensis is found mostly on the outer rows of sub-terminal papillae with 3–6 papil- coast, or if in bays, only in very clean coarse lae per row (five per row in the illustrated sand. It has a distinctive V-shaped pigment specimen). Mid-dorsal and mid-ventral dis- pattern (sometimes with red spot at center) tal areas of the proboscis are without papil- of pigmentation on the lower end of the pro- lae and smooth (Lovell 1997; Hilbig 1997) stomium, a smooth proboscis without medial (Fig. 3). papilla, soft silky flowing setae and inter- Genitalia: ramal cirri beginning on the third setiger. Nephridia: Three other Nephtys species that are not so easily confused with N. caecoides. Possible Misidentifications N. cornuta, a small species (less than 15 Worms of the family Nephtyidae mm in length) that can be identified by its can be distinguished by their anteriorly cy- distinctive bifid ventral and posterior anten- lindrical and posteriorly rectangular bodies nae. This species often retains larval eyes (in cross section), well-developed bi-lobed on the third setiger, a feature which is usual- parapodia, interramal cirri, four small pro- ly lost in other closely related species (Blake stomial antennae, and eversible globular and Ruff 2007). N. cornuta can also be dif- proboscis with terminal rows of papillae. ferentiated because it has 18 distal paired They are strong and muscular worms that papillae (instead of 20 in N. caecoides) and can be good burrowers and strong swim- interramal cirri that begin on setiger five mers (Blake and Ruff 2007). Nephtyids (rather than four in N. caecoides) (Lovell superficially resemble the genus Nereis, 1997). N. punctata is much like N. caeca in however, they have no long anterior ap- size and form (Hartman 1938), but has pendages (tentacular cirri) and their pro- interramal cirri beginning on setiger 8–10, boscis armature is quite different (Kozloff and with incised acicular lobes in the 1993). The distinctive taxonomic charac- anterior parapodia. This species is large ters of N. caecoides include 20 distal and muscular with wide body and short paired papillae, 22 rows of sub-distal papil- parapodia and is currently only reported in lae with 3–6 papillae per row, an unpaired southern California (Hilbig 1997; Blake and mid-dorsal papilla and interramal cirri be- Ruff 2007) ginning on setiger four (Lovell 1997). N. parva, colorless except for a dark Some Nephtys species are distin- spot in the middle of its prostomium guished from each other by very fine mor- (Hartman 1968), a smooth proboscis proxi- 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] mally, no medial papilla, eyespots on its meters MLLW (Clark and Haderlie 1962). In- third setiger and interramal cirri beginning dividuals observed from 0.0 m to +1.2 m, with on the fourth setiger. The type material 15 specimens collected at 0.0 m, 7 specimens from this species is suspected to have at +0.9 m and 1 specimen at +1.2 m (Johnson been miscurated and the holotype appears 1970). to be that of N. cornuta, while the species Associates: Nephtys caeca has much the description and paratypes match N. cae- same habitat (Porch 1970). coides more closely. Thus, this species is Abundance: One of the most common not a currently a valid taxon (Lovell 1997; nephtyids in California where San Francisco Blake and Ruff 2007). Bay densities were recorded at 130 individu- N. ferruginea has the same number als/m2 (Jones 1961) and Bodega Bay densi- of paired distal and sub-distal papillae, ties were 32 individuals/m2 (Clark and Hader- however, the interramal cirri in this species lie 1962). The most commonly found begin on setiger three, rather than four in nephtyid in Coos Bay and distribution is a fun- N. caecoides (Lovell 1997). N. ferruginea ction of protection from exposure, rather than individuals have a distinct rust colored other physical factors (e.g. salinity or tempe- pigment in a V-shape pattern on rature, Porch 1970). prostomium in addition to transverse bars Life-History Information mid dorsally on the first 20 setigers and Reproduction: The reproduction and larval oblique stripes dorsolaterally (Hilbig 1997). development of N. caecoides is not known. Ecological Information However, Nephtys species are usually free- Range: Type locality is Tomales Bay, Cali- spawning with pelagic development that pro- fornia (Hartman 1968). Known range in- ceeds via a trochophore larva (e.g. N. caeca, cludes western Canada to southern Califor- Fernald et al. 1987; Crumrine 2001). nia. Larva: Nephtyid trochophore larvae have a Local Distribution: Coos Bay distribution pair of eyes, dome-shaped prostomium and includes many stations, especially those barrel-shaped body. They have well devel- within the South Slough. The distribution of oped prototrochs and telotrochs, with neu- N. caecoides is very close to Scoletoma zo- rotrochs present in young larvae. Nephtyid nata but occurs in sandier mud (Porch larvae are common in plankton samples and 1970).