Eclipidrilus pacificus Steven & Fend, 2005, n. sp.

Eclipidrilus pacificus n. sp. (Figures 1–10) HOLOTYPE: USNM 1073033. A whole mounted worm in Kleermount. TYPE LOCALITY: Washington: Jefferson Co.: pool in small spring next to the Hoh River, 47º49’00”N, 124º06’46”W, in mud and macrophyte roots in shallow water. PARATYPES: From the type locality. USNM 1073034–1073037: 2 sectioned worms (1 sagittal, 1 transverse), 1 whole mount, 2 dissected and slide mounted. Collected by S. Fend. 29.IV.1999. OTHER MATERIAL: Typical specimens: Washington: Clallam Co: muddy seep beside Road 29, Calawah River drainage, 47º57’29”N, 124°14'31"W, 26.IV.2004. 4 dissected. Jefferson Co: from the type locality, 29.IV.1999. 1 whole mount, 1 longitudinally dissected. 2.VI.2003. 4 whole mounts, 4 dissected; 2 partially mature, dissected. Small tributary to Clearwater River at Coppermine Bottom Camp, 47°39'21"N, 124°11'58"W, 25.VI.2004. 8 dissected. Pacific Co.: South Naselle River near Knappton, 46°17'38"N, 123°48'36"W, 25.VI.2004. 5 dissected. All collected by S. Fend. Variant 1: Idaho: Latah Co.: Palouse River at Laird Park, 46º56’35”N, 116º38’29”W, 2.V.2000, collected by D. L. Gustafson. 1 dissected. Shoshone Co.: Middle Fork Saint Maries River near Two Bit Creek, 47°00’08”N, 116°10’30”W, 28.VII.2003, collected by D. L. Gustafson. 2 dissected. Oregon: Yamhill Co.: small spring west of Peavine Ridge, in mud and macrophyte roots, slow current, 45º14’19”N, 123º 22’50”W, 30.I.2000. 1 whole mount, 1 dissected, 2 sectioned (1 sagittal, 1 transverse). 10.V.2001. 6 whole mounts. Lane Co.: small spring and stream beside Fox Hollow Rd., Eugene, in mud, 44º00’36”N, 123º04’50”W, 29.I.2000. 3 whole mounts. 1.VI.2003. 4 dissected, 3 whole mounts, 2 sectioned (1 sagittal, 1 transverse). Spring at mouth of Tenmile Creek, in mud and macrophyte roots, shallow water with slow current, 44º13’30”N, 124º06’29”W, 30.I.2000. 2 whole mounts. Washington: Pierce Co.: Taylor Bay Inlet, 9.IX.2003, collected by M. Allen. 3 dissected. Worms collected by S. Fend unless otherwise noted. Variant 2: Oregon: Clatsop Co.: Columbia River estuary at Snag Island, VIII.1980, collected by E.J. Clairain and C. Newling. 8 whole mounts, from the Royal Ontario Museum, No.1989­037, slides labeled 1, 5, 7, 8, 9, 11, 16, 17. Karlson Island (Columbia River estuary), 28.VI.2002, collected by R. Draheim. 1 whole mount, 3 dissected, 2 sagittally sectioned. Knappa Slough at dock (Columbia River estuary), 24.VI.2002, collected by R. Draheim. 5 dissected. Warren Slough (Columbia River estuary), 28.VI.2002, collected by R. Draheim. 2 whole mounts, 1 dissected. Tillamook Co.: spring beside Nestucca River, 7 km upstream of Blaine, 4.VI.2003, collected by S. Fend. 1 dissected. Partially mature, undetermined: Pacific Co.: small spring along the Naselle River, 46º24’00”N, 123º43’42”W, in mud and macrophyte roots, 30.IV.1999, collected by S. Fend. 1 dissected. Pierce Co.: Little Mashell Creek, 20.IX.2001, collected by M. Allen. 1 whole mount. Description Typical specimens Length of preserved worms 17–32 mm, 69–107 segments; width 0.52–0.80 mm in X, maximum width to 0.82 mm. Secondary segmentation prominent in segments V–X, resulting in a narrow anterior ring in each segment; variable in posterior segments (Fig. 1 A–B). Chaetae sigmoid, simple­pointed, with nodulus 29–38% of chaeta length from tip (Fig. 2 A). Chaeta length 125–170 µm in mid­body; slightly shorter in posterior segments, but proportions similar in anterior and posterior segments. Dorsal and ventral chaetae approximately equal in length; within each bundle, the outer (more lateral) chaeta slightly shorter than the inner. Prostomium rounded­conical, about 0.3 mm long, width about equal to length. Brain in I, not strongly lobed. Pharynx in II–IV; dorsal wall with columnar cells; ventral wall much thinner than dorsal anterior to IV (Fig. 2 B, cf. Fig. 14 A). Pharyngeal glands in V–VII(VIII). Longitudinal muscle layer 20–35 µm thick in preclitellar segments; circular muscle layer 5–7 µm; both layers thinner in posterior segments. Epidermis 10–20 µm thick anterior to clitellum; to about 35 µm in clitellum. Dorsal blood vessel passes under the brain in I before dividing; the two forks pass around the buccal cavity and rejoin in V as a single ventral vessel. One pair of lateral, commissural blood vessels joins dorsal vessel in segments anterior to XII; each commissure strongly convoluted, and those in the first few segments usually enter the next segment before joining the ventral vessel (Fig. 2 B). Commissures in X and XI loop into sperm and egg sacs. Dorsal vessel without lateral vessels between the clitellar segments and about the posterior 1/2 to 1/3 of the body. Beginning near mid­body or posteriorly, two pairs of short, blind lateral blood vessels usually branch off the dorsal vessel in each segment. Lateral vessels are longer, with up to 5–10 short branches in the posterior 1/3 to 1/4 of some specimens (Fig. 2 D), but remain short and inconspicuous in others (Fig. 2 C). Perivisceral sinus begins in VII; chloragogen cells begin in VII or VIII. First nephridia usually paired on 6/7, the next on 12/13 or posterior; nephridia in few to most posterior segments, paired or on one side only. Each nephridium has a small anteseptal funnel, a granular postseptal thickening, and an irregular, posterior duct 18–20 µm in diameter. The posterior duct branches, with a short branch to the nephropore anterior to ventral chaetae. Another branch extends along the ventral blood vessel as a convoluted mass, entering posterior and/or anterior segments; posterior to XIII it appears continuous with ducts from other nephridia across multiple segments. Nephropores simple, inconspicuous. Testes paired in IX and X, smaller in IX. Ovaries paired in XI; usually elongate, extending to 11/12 or into XII. Sperm sacs paired, extending back as far as XXII; egg sacs may extend 1 or 2 segments beyond sperm sacs. Female funnels up to 120 µm tall, with the posterior side much longer than the anterior; female pore intersegmental, on 11/12. Clitellum IX–XIII. Single male pore midventral (beneath the ventral nerve cord) in X, behind the ventral chaetae (Figs. 1 A–B, 3A, 4A). A short, cylindrical penis is contained within a shallow concavity, within a ring of thickened epidermis 170–340 µm in diameter (Figs. 4 A, 5B,D, 8A–B). Epidermal cells within the concavity interspersed with narrow ducts from large (160–300 µm tall), petiolate accessory glands; gland mass to 550 µm wide (Figs. 4 A, 8A). Penis variably extended, 20–160 µm long and 40–50 µm wide, formed by extrusion of the atrial duct epithelium. Epithelial cells in the most ectal part of the duct have basal nuclei and fibrous, ectally­directed extensions that appear continuous with the penis (Figs. 4 A, 5D, 8B). Lumen at ectal end appears slightly cuticular, and may appear irregular or sinuous (Fig. 5 D, 8B). Atrium extending as far as XIX, with distinct ectal duct and ental ampulla (Fig. 3 A). Atrial duct 600–2300 (1530) µm long. The ectal half is a 60–100 µm diameter tube of loose, mostly longitudinal muscle, about 20 µm thick, with an inner epithelium that changes from columnar to elongate­fibrous in about the ectal 200 µm, near the male pore (Figs. 4 A, 5B). Ental portion of duct about 40 µm in diameter with a thinner (4–6 µm) muscle layer that is mostly longitudinal, with a very thin (ca. 1 µm) inner circular layer. Ampulla nearly cylindrical, but tapered ectally; length 520–1900 (890) µm, maximum diameter of muscle tube 130–220 (180) µm. Ampulla with an outer layer of longitudinal muscle 22–50 (38) µm thick, an inner transverse­circular layer 10–25 (15) µm thick, and epithelium 8–19 µm thick (Figs. 5 A, 9A–C). Fibers in the longitudinal muscle layer in radially arranged lamellae (Fig. 9 B), parallel to the long axis of the ampulla, slightly sinuate, but not arranged in opposing layers. The inner, transverse muscle layer has parallel fibers arranged orthogonally to the long axis of the atrium (Fig. 9 A–C). Lumen of ampulla variable, 12–100 (42) µm wide, or 0.08–0.61 (0.27) times atrium diameter. The atrial ampulla is covered with a single layer of small cells (possibly nuclei of muscle cells) and a layer of densely packed, multicellular prostate glands (Fig. 5 A, 9A–C). Prostatic cells are narrowly petiolate, usually occurring in small bundles of up to about 10 cells; individual bundles 40–90 µm tall. Male funnels paired on 9/10 and 10/11; the anterior pair smaller than the posterior (median height 100 µm vs. 160); the posterior pair usually extends back into XI within the sperm sac. Both anterior and posterior male funnels usually functional, with associated sperm. Both anterior and posterior vasa deferentia narrow (8–16 µm diameter). All four vasa deferentia join the atrial duct, running outside the muscle layer until the ampulla, where they gradually pass through the muscle layers (Fig. 9 B) and eventually the epithelium, and enter the ental part of the lumen. Posterior vasa deferentia enter X directly, without penetrating 10/11 and forming a loop in XI. Spermathecae paired in IX; pores on ventral chaetal lines, near the anterior septum (8/ 9), usually within the narrow, secondary annulus (Fig. 1 A–B). Pores usually prominent, sometimes on low mounds. Each spermatheca has a narrow ectal duct 230–720 (370) µm long, and a distinct ental ampulla 420–1330 (680) µm long by 130–410 µm wide (Fig. 6 A,D). The ectal end of the duct widens into a narrow vestibule 145–310 (215) µm deep by 64–96 (77) µm wide, with a mostly longitudinal muscle layer surrounding a very thin transverse­circular layer and columnar lining cells with basal nuclei (Figs. 6 A, 10A). Entally, the duct narrows abruptly, forming a short, convoluted section inside the muscle tube (Fig. 6 A). A short band of thickened, transverse­circular muscle surrounds and constricts the beginning of this section (Fig. 10 A). Near the midpoint, the duct widens; the ental half is 40–50 µm in diameter; a thin (3–4 µm), mus

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