Figures 10–11
Anthosoma robustum Verrill, 1873: 49, 54, 71, 134, 303, pl. 14, fig. 76.
Scoloplos robustus: Verrill 1881: 301, 317; Andrews 1891: 292; Sumner, et al. 1913: 624.
Scoloplos robusta: Webster & Benedict 1884: 724.
Scoloplos bustoris Eisig, 1914:422–423; Hartman 1942: 58–60, figs. 111–112; Horn & Bookhout 1950: 1, pls. 1–4. Fide Hartman 1957.
Haploscoloplos tortugaensis Monro, 1933a: 261–263, fig. 10a–d. Fide Mackie 1987.
Scoloplos rufa Treadwell, 1941: 1, figs. 1–6. Fide Hartman 1956.
Haploscoloplos bustoris: Hartman 1945: 30. Fide Hartman 1957.
Haploscoloplos robustus Hartman 1951: 78, pl. 21, figs. 4–6; 1956: 258, 268, 290; 1957: 272, pl. 25, figs 4–6; Day 1973: 91; Trott 2004: 280.
Scoloplos (Scoloplos) robustus: Pettibone 1963: 288–290, fig. 76g.
Leitoscoloplos robustus: Taylor 1984 1.17–1.19, fig. 1.16a–f; Mackie 1987: 16–18, fig. 17; Fauchald, Granados-Barba & Solís- Weiss 2009: 763; Blake 2017: 18.
Material examined. (145 specimens) Northeastern USA, Gulf of Maine, Damariscotta River Estuary, Lowes Cove, coll. G. Noyes, 7 Aug 1966, 43°56.012′N, 69°34.688′W, intertidal (5, MCZ 161587); upper end Pleasant Cove, coll. V. Walker, 19 Aug 1966, 43°54.956′N, 69°35.844′W, intertidal (21, MCZ 161588); Cove inside of Little Point, coll. D. Dorsey and V. Walker, 12 Aug 1966, 44°01.196′N, 69°32.823′W, 1–2 m (3, MCZ 161589); Seal Cove, coll. D. Dorsey and G. Noyes, 03 Aug 1966, 43°53.161′N, 69°34.119′W, 1–2 m (4, MCZ 161590); Peter’s Island, coll. V. Walker, 01 Sep 1966, 43°54.504′N, 69°33.764′W, 1–2 m (16, MCZ 161591); Middle Pleasant Cove, coll. D. Dorsey and V. Walker, Sep 1966, 43°55.259′N, 69°35.167′W, 1–2 m (66, MCZ 161592); Long Cove, coll. D. Dorsey and V. Walker, 04 Aug 1966, 43°54.299′N, 69°33.859′W, 1 m (5, MCZ 161594).— Connecticut, Long Island Sound, US EPA Dredged Material Disposal Site Survey, Sta. NLLRF, Rep. 2, 17 Feb 2000, 41°16.710′N, 72°02.000′W, 16 m (1, MCZ 161596).— New York, Long Island Sound, off Northport, pipeline survey, Sta. IG- 01, coll. P.L. Neubert, 27 Oct 1999, 40°55.75′N, 73°20.73′W, 3 m (1, MCZ 161682). Eastchester Bay, off Locust Point, pipeline survey, Sta. LP 2, Rep. 1, coll. P.L. Neubert, 14 Jul 2000, 40º49.201′N, 73º48.016′W, 4.5 m (14, MCZ 161593).— Off New Jersey, Atlantic Ocean, August 2008; Excalibur pipeline survey, Sta. 39B, coll. P.L. Neubert, 40°16.4468′N, 73°42.6671′W, 28 m (1, MCZ 161595).— Massachusetts, New Bedford Harbor, Long-term Monitoring Program, 1999 September-October Survey. Sta. 208-2, 23 Sep 1999, 41°38.981′N, 70°55.022′W, 1.3 m (1, MCZ 161575); Sta. 306-3, 14 Sep 1999, 41°37.15′N, 70°52.237′W, 2.8 m (1, MCZ 161576).— Off Massachusetts, Georges Bank, Benthic Infauna Monitoring Program, coll. G.W. Hampson, Chief Scientist. Sta. 4: Cruise M 6, R/V Oceanus, Rep. 2, 25 Nov 1982, 40°50.7′N, 68°00.2′W, 65 m (2, USNM 1620911); Cruise M10, R/V Oceanus, Rep. 2, 14 Nov 1983, 40°50.7′N, 68°00.2′W, 67 m (1, USNM 1620912). Sta. 10: Cruise M 1, R/ V Eastward, Jul 1981, Rep. 5, 40°,42.0′N, 68°36.0′W, 62 m (1, USNM 1620913); Cruise M 3, R/ V Endeavor, Rep. 5, 12 Feb 1982, 40°42.0′N, 68°35.1′W, 62 m (1, USNM 1620914); Cruise M 4, R/ V Cape Henlopen, Rep. 2, 16 May 1982, 40°42.0′N, 68°35.2′W, 62 m (1, USNM 1620915); Cruise M5, R/V Oceanus, Rep. 6, 28 Jul 1982, 40°42.0′N, 68°35.3′W, 56 m (1, USNM 1620916); Cruise M 8, R/ V Gyre, Rep. 4, 20 May 1983, 40°42.0′N, 68°35.2′W, 62 m (1, USNM 1620917); Rep. 5, (4, USNM 1620918). Sta. 11: Cruise M 2, R/V Oceanus, Rep. 2, 12 Nov 1981, 40°30.8′N, 68°33.5′W, 80 m (1, USNM 1620919); Rep. 5 (1, USNM 1620920); Cruise M 3, R/ V Endeavor, Rep. 1, 12 Feb 1982, 40°30.8′N, 68°33.6′W, 86 m (1, USNM 1620921); Rep. 2 (1, USNM 1620922); Cruise M 4, R/ V Cape Henlopen, Rep. 3, 16 May 1982, 40°30.8′N, 68°33.7′W, 83 m (2, USNM 1620923); Cruise M 6, Rep. 3, R/V Oceanus, 26 Nov 1982, 40°30.8′N, 68°33.7′W, 83 m (1, USNM 1620924); Cruise M 8, R/ V Gyre, Rep. 4, 20 May 1983, 40°30.8′N, 68°33.7′W, 84 m (1, USNM 1620925); Cruise M11, R/V Oceanus, Rep. 1, 14 Nov 1983, 40°30.8′N, 68°33.7′W, 86 m (1, USNM 1620926); Cruise M 12, R/ V Gyre, Rep. 6, 3 Jun 1984, 40°30.8′N, 68°33.7′W, 86 m (2, USNM 1620927).
Description. A large species, specimens from Georges Bank (USNM 1620918) up to 9.5 cm long, 3.5 mm wide across thoracic setigers, with 280 setigers (one complete); smaller specimens from Maine up to 17.5 mm long, 1 mm wide across thoracic setigers, with 125 setigers (complete specimen). Body elongate, with thoracic segments and anteriormost abdominal segments dorsoventrally flattened, with individual segments short, about 4–5 times wider than long; individual segments separated by narrow transverse groove (Figs. 10A, 11A). Individual thoracic and anterior abdominal segments with thin, transverse ridge extending between parapodia and entirely across dorsal and ventral surfaces producing a biannulate appearance (Fig. 11 A–C). Abdominal segments becoming longer with a narrow intersegmental ring anterior to larger segmental ring continuing ventrally between neuropodia. Middle and posterior segments about twice as wide as long. Shallow mid-ventral groove present from middle abdominal segments to near posterior end. Color in alcohol light tan.
Pre-setiger region triangular, elongate, as long as first 2½ setigers (Fig. 10 A–C). Prostomium conical, tapering to pointed tip; nuchal organs curved slits on posterior lateral margin (Fig. 10A); eyespots absent. Peristomium a single smooth achaetous ring dorsally (Fig. 10 A–B), ventrally encompassing mouth with upper lip formed of two large lobes and lower lip with curved row of ten or more narrow elongate lobes (Fig. 10C). Proboscis with one or more lobes when everted.
Thorax on larger specimens with 22–25 setigers with abrupt transition to abdominal segments. Boundary between thorax and abdomen indicated by elongation of neuropodia and decrease in number of neurosetae. Thoracic notopodial postsetal lobes short, weakly triangular in shape, narrowing apically, arising directly from body wall (Fig. 10 D–E). Abdominal notopodia becoming longer, digitiform in middle and posterior segments (Fig. 10 F– G).Thoracic neuropodial postsetal lobes short, stubby, arising from broadly rounded base (Fig. 10D); last 1–3 thoracic neuropodia with extra postsetal lobe and usually a short subpodial papilla resulting in one or two final thoracic setigers with three short lobes on largest specimens (Fig. 10E). Abdominal neuropodia thickened, becoming relatively short in middle and posterior segments, each narrowing to pointed apical lobe bearing subterminal ventral cirrus on lateral margin (Fig. 10F); extra postsetal lobes or subpodial papillae appearing to merge into subpodial flange over first 3–4 abdominal setigers (Fig. 10F); subsequent middle and posterior abdominal setigers with large, thickened, subterminal flange ventral to neuropodium (Fig. 10G); subpodial papillae absent on abdominal segments. Prominent interramal cirrus present on anterior abdominal setigers (Fig. 10F); narrow, conical or fingerlike at first, continuing for about 75 setigers, then reduced to short ciliated patch and/or protuberance in middle setigers (Fig. 10G); entirely absent in posterior setigers.
Branchiae typically from setiger 20–23, usually 22; initial thoracic branchiae short, papilliform (Fig. 10E), becoming full size by about setigers 25–27 or anterior abdominal segments (Fig. 10F). Anterior branchiae triangular, tapering to rounded apex; branchiae of middle and posterior segments becoming narrower and longer (Fig. 10G); each branchia with transverse folds and cilia on inner and outer margins.
Notosetae all camerated capillaries; furcate and flail setae not observed; capillaries of thoracic notopodia numbering about 50 in 4–5 irregular rows, reduced to about 25 in abdominal segments. Thoracic neurosetae all camerated capillaries with about 75–100 in 5–6 rows; abdominal neurosetae 8–9 long stiff capillaries with barbs along one edge and 1–3 imbedded aciculae, none observed protruding.
Pygidium consisting of numerous lobes surrounding anal opening; with two thin anal cirri attached laterally (Fig. 10H).
Variability. Smaller specimens with 14–19 thoracic setigers and branchiae from setigers 13–17 have been recorded (Mackie 1987; specimens from Maine in the present study). However, the nature of the extra postsetal lobes in the last thoracic neuropodia and relatively smooth form of the abdominal subpodial flanges of the neuropodia are similar to those of the larger specimens.
Remarks. Leitoscoloplos robustus is the largest known species of the genus (Pettibone 1963; Mackie 1987). Pettibone (1963) reported specimens having 300 setigers, a length of 37.5 cm and a thoracic width of 10 mm. The largest specimen measured in this study had 280 setigers and was 9.5 cm long and 3.5 mm wide across thoracic setigers. It is likely that larger specimens are in the Georges Bank samples, but most specimens were coiled upon preservation, including one that was complete and could not be accurately measured.
Leitoscoloplos robustus differs from the closely related L. fragilis in that the latter species has extra subpodial papillae in abdominal segments that continue posteriorly along most of the body and that typically divide the subpodial flange into separate lobes. In contrast, L. robustus has no abdominal subpodial papillae or lobes after the first 2–3 abdominal setigers and the borders of the subpodial flanges are therefore smooth and entire along most of the body. In addition, L. robustus has prominent neuropodial ventral cirri in abdominal setigers that is reduced or inconspicuous in L. fragilis.
Although similar morphologically, the distinction between L. fragilis and L robustus among specimens from the eastern U.S. was supported in a molecular analysis by Bleidorn (2009). In the same analysis, L. robustus specimens from Maine and Florida were shown to exhibit only minor genetic differences.
Distribution. Eastern Canada to Florida, intertidal to 86 m; northern Gulf of Mexico, Florida, intertidal to 10 m.
Genus Scoloplos de Blainville, 1828
Type species: Lumbricus armiger Müller, 1776, by monotypy.
Synonym: Scolaricia Eisig, 1914. Type-species: Scolaricia typicus Eisig, 1914, by monotypy. Fide Day 1973.
Diagnosis. (Emended). Prostomium pointed, usually prolonged; single achaetous peristomial ring. Branchiae first present from middle or posterior thoracic setigers or from abdominal setigers (8–26). Posterior thoracic setigers with 0–2 postsetal lobes and 0–2 subpodial lobes, never more than four lobes of both types combined; not forming ventral fringes. Thoracic neurosetae including blunt, inconspicuous uncini, few or many in distinct rows; accompanied by few to many crenulated capillaries; furcate setae usually present; heavy spear-like spines and bristle-topped setae absent. Abdominal neuropodia with imbedded, non-projecting acicula. Abdominal noto- and or neuropodial flail setae present or absent.
Remarks. Specimens of Scoloplos having thoracic neuropodial uncini or hooks and extra neuropodial postsetal or subpodial lobes have for the most part been identified as S. armiger (Müller, 1776), resulting in the species being identified from wide geographic areas and thus considered cosmopolitan (Hartman 1957; Pettibone 1963; Hartmann-Schr̂der 1971, 1996; Blake 1996). Accounts of S. armiger among European investigators, however, suggest that several species are involved. For example, McIntosh (1910) described specimens that have only a few thoracic neuropodial uncini or spines; whereas Hartmann-Schr̂der (1971, 1996) described specimens with numerous thoracic neuropodial uncini. Supporting the view that European S. armiger may represent a suite of species, recent investigations have demonstrated that different populations in shallow and subtidal locations in the North Sea are ecologically and reproductively isolated from one another (Kruse & Reise 2003; Kruse et al. 2003, 2004). Results from molecular sequence data also support these observations (Bleidorn et al. 2006). Additionally, these authors determined that specimens from the type locality in Norway represented yet a third species. These results suggest that at least three cryptic species are likely present among northern European specimens collectively identified as S. armiger. Bleidorn et al. (2006, 2009) also provided molecular results on some orbiniids from California in the eastern Pacific identified locally as S. armiger that might represent additional undescribed species. To date, none of these various species have been described or redescribed, including specimens from the type locality.
Previous studies along the U.S. Atlantic coast have reported species of Scoloplos as S. armiger, the widely reported European species, and S. acmeceps, an eastern Pacific species (Pettibone 1963; Maciolek-Blake et al. 1985; Trott 2004). The present morphological study of Scoloplos specimens from shelf and slope depths along the U.S. Atlantic coast suggest that several distinct species are present, none of which are either S. armiger or S. acmeceps. Three basic morphotypes are evident: (1) specimens with rows of numerous thoracic neuropodial uncini or hooks and with no extra postsetal or subpodial lobes; (2) specimens with thoracic neuropodial uncini reduced to a single row or a few isolated ventral spines and with extra postsetal and/or subpodial lobes; (3) specimens with 3–4 rows of numerous thoracic neuropodial uncini and with extra postsetal and/or subpodial lobes. Within these three basic morphotypes, there is considerable additional morphology available to separate individual species. These include differences in (a) the pre-setiger morphology with details of the upper and lower lips of the mouth, (b) the shape and form of the thoracic noto- and neuropodia, (c) the presence and form of subpodial flanges with or without internal glands, (d) the shape of the branchiae along the body, (e) the presence or absence of an interramal process or cirrus, (f) the presence or absence of notopodial furcate setae, (g) details of the intersegmental areas, and (h) pygidial morphology. These characters and other aspects of the following five species identified from shelf and slope depths along the U.S. Atlantic coast are reported:
Genus Scoloplos de Blainville, 1828
Type species: Lumbricus armiger Müller, 1776, by monotypy.
Synonym: Scolaricia Eisig, 1914. Type-species: Scolaricia typicus Eisig, 1914, by monotypy. Fide Day 1973.
Diagnosis. (Emended). Prostomium pointed, usually prolonged; single achaetous peristomial ring. Branchiae first present from middle or posterior thoracic setigers or from abdominal setigers (8–26). Posterior thoracic setigers with 0–2 postsetal lobes and 0–2 subpodial lobes, never more than four lobes of both types combined; not forming ventral fringes. Thoracic neurosetae including blunt, inconspicuous uncini, few or many in distinct rows; accompanied by few to many crenulated capillaries; furcate setae usually present; heavy spear-like spines and bristle-topped setae absent. Abdominal neuropodia with imbedded, non-projecting acicula. Abdominal noto- and or neuropodial flail setae present or absent.
Remarks. Specimens of Scoloplos having thoracic neuropodial uncini or hooks and extra neuropodial postsetal or subpodial lobes have for the most part been identified as S. armiger (Müller, 1776), resulting in the species being identified from wide geographic areas and thus considered cosmopolitan (Hartman 1957; Pettibone 1963; Hartmann-Schr̂der 1971, 1996; Blake 1996). Accounts of S. armiger among European investigators, however, suggest that several species are involved. For example, McIntosh (1910) described specimens that have only a few thoracic neuropodial uncini or spines; whereas Hartmann-Schr̂der (1971, 1996) described specimens with numerous thoracic neuropodial uncini. Supporting the view that European S. armiger may represent a suite of species, recent investigations have demonstrated that different populations in shallow and subtidal locations in the North Sea are ecologically and reproductively isolated from one another (Kruse & Reise 2003; Kruse et al. 2003, 2004). Results from molecular sequence data also support these observations (Bleidorn et al. 2006). Additionally, these authors determined that specimens from the type locality in Norway represented yet a third species. These results suggest that at least three cryptic species are likely present among northern European specimens collectively identified as S. armiger. Bleidorn et al. (2006, 2009) also provided molecular results on some orbiniids from California in the eastern Pacific identified locally as S. armiger that might represent additional undescribed species. To date, none of these various species have been described or redescribed, including specimens from the type locality.
Previous studies along the U.S. Atlantic coast have reported species of Scoloplos as S. armiger, the widely reported European species, and S. acmeceps, an eastern Pacific species (Pettibone 1963; Maciolek-Blake et al. 1985; Trott 2004). The present morphological study of Scoloplos specimens from shelf and slope depths along the U.S. Atlantic coast suggest that several distinct species are present, none of which are either S. armiger or S. acmeceps. Three basic morphotypes are evident: (1) specimens with rows of numerous thoracic neuropodial uncini or hooks and with no extra postsetal or subpodial lobes; (2) specimens with thoracic neuropodial uncini reduced to a single row or a few isolated ventral spines and with extra postsetal and/or subpodial lobes; (3) specimens with 3–4 rows of numerous thoracic neuropodial uncini and with extra postsetal and/or subpodial lobes. Within these three basic morphotypes, there is considerable additional morphology available to separate individual species. These include differences in (a) the pre-setiger morphology with details of the upper and lower lips of the mouth, (b) the shape and form of the thoracic noto- and neuropodia, (c) the presence and form of subpodial flanges with or without internal glands, (d) the shape of the branchiae along the body, (e) the presence or absence of an interramal process or cirrus, (f) the presence or absence of notopodial furcate setae, (g) details of the intersegmental areas, and (h) pygidial morphology. These characters and other aspects of the following five species identified from shelf and slope depths along the U.S. Atlantic coast are reported: