Research Article |
Corresponding author: María Capa ( maria.capa@ntnu.no ) Academic editor: Greg Rouse
© 2016 María Capa, Karen J. Osborn, Torkild Bakken.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Capa M, Osborn KJ, Bakken T (2016) Sphaerodoridae (Annelida) of the deep Northwestern Atlantic, including remarkable new species of Euritmia and Sphaerephesia. ZooKeys 615: 1-32. https://doi.org/10.3897/zookeys.615.9530
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Sphaerodoridae (Annelida) is a seeming uncommon and minimally diverse group of polychaetes in the northwestern Atlantic, with only seven species reported from the United States, and none from the eastern coast of Canada, before the present study. Review of the large Smithsonian collection (National Museum of Natural History, Washington) revealed the presence of two morphologically extraordinary undescribed species and added a new record to the north-western Atlantic region. Euritmia carolensis sp. n. is characterised by bearing approximately 20 sessile spherical papillae arranged in three transverse rows per segment, ventrum with 4–6 larger papillae near the parapodial bases and parapodia without papillae; bearing 4–5 simple chaetae that are enlarged subdistally. Sphaerephesia amphorata sp. n. is distinguished from other congeners in the presence of four longitudinal rows of sessile, bottle-shaped macrotubercles with exceptionally long digitiform terminal papilla, and parapodia with four rounded and small papillae, bearing 4–7 compound chaetae, with blades 7–11 times as long as wide. Other encountered species are also herein re-described, including intraspecific variation and updated iconography. Comparison of material also allowed some systematic changes in the group, including the synonymisation of the genus Amacrodorum with Euritmia, and the transfer of Ephesiopsis shivae to Ephesiella. A key to the species reported from the Northwestern Atlantic is provided.
Generic synonymy, Amacrodorum , Ephesiopsis , epithelial tubercles, NW Atlantic, shelf, slope
The northwest Atlantic (considered herein as the continental shelf and slope areas off Atlantic Canada and New England) is a relatively well-studied area in terms of its benthic polychaete fauna (e.g.
Species recorded in northwestern Atlantic shelf, slope and abyssal depths.
Species | Type locality |
---|---|
Clavodorum atlanticum Hartman & Fauchald, 1971 | Northwest of Bermuda, 37°59.2'N, 69°26.2'W, 3834 m depth. |
Ephesiella macrocirris Hartman & Fauchald, 1971 | Off New England, 39°46.5'N, 70°43.3'W, 1470–1330 m depth. |
E. mixta Hartman & Fauchald, 1971 | Off New England, 38°33'N, 68°32'W, 3753 m depth. |
Sphaerororidium minutum (Webster & Benedict, 1887) | Off New England, mainly shelf depths |
Sphaerodoropsis corrugata Hartman & Fauchald, 1971 | Off New England, 39°56'30"N, 70°39'54"W, 400 m depth. |
S. elegans Hartman & Fauchald, 1971 | Off Brazil, 00°03.0'S, 27°48.0'W, 3730–3783 m depth. |
S. longipalpa Hartman & Fauchald, 1971 | Bermuda Slope, 32°16'36"N, 64°36'18"W, 1700 m depth. |
Revision of the sphaerodorids deposited at the Smithsonian collection, National Museum of Natural History, Washington, revealed undescribed species fitting the definition of Euritmia Sardá-Borroy, 1987 and Sphaerephesia Fauchald, 1972, but presenting noteworthy attributes never described in any member of either of these two groups. Euritmia hamulisetosa Sardá-Borroy, 1987, type species of the genus, was described from shallow subtidal environments in southern Spain. Euritmia capense (Day, 1963) is so far considered the only congener and reported from South Africa (
Members of Sphaerephesia, a genus with nine nominal species described to date, are recognised by the presence of macrotubercles with a terminal papilla and compound chaetae (
For this study, specimens of previously described species from the area were also examined, allowing re-description of Ephesiopsis guayanae Hartman & Fauchald, 1971, Sphaerodoridium minutum (Webster & Benedict, 1887) and Sphaerodoropsis corrugata Hartman & Fauchald, 1971. Each of these species is also peculiar and inhabit the northwestern Atlantic. In the process of re-describing these species we comment on the morphological intraspecific variability observed.
This study does not intend to represent an exhaustive taxonomic account of the sphaerodorid fauna of the northwest Atlantic. Instead, the aim is to highlight the need of further benthic surveys and taxonomic revisions of the material housed in museum collections in order to increase the knowledge of the biodiversity inhabiting the northwestern Atlantic Ocean floor, including the description of new species with remarkable morphological characteristics that may assist in understanding the morphological variation of the family.
Specimens deposited in the collections of the
Methylene-blue staining was used to highlight glandular areas and papillae by immersing selected specimens in 70–80% ethanol with some dissolved crystals of the compound for several minutes. Micrographs were taken with a Leica DFC 420 camera attached to a Leica MZ 16A stereo microscope and a Leica DM 6000B compound microscopes (Leica Microsystems, Wetzlar, Germany). Stacks of multi-focus shots were merged into a single photograph to improve resolution with Leica Application Suite v3.7 software (Leica Microsystems, Wetzlar, Germany). Some parapodia were mounted on microscope slides with glycerine.
Scanning electron micrographs were taken on specimens after dehydrating them in a series of 70, 80, and 90% ethanol and series of mixtures of absolute ethanol and Hexamethyldisilazane (HMDS) with the following ratios 2:1, 1:1, 1:2, and then into pure HMDS. The prepared samples were mounted on holders, sputter-coated with gold (10 nm thickness). The micromorphology and topography were determined using a Philips FEI INSPECT (Hillsboro, Oregon, USA) scanning electron microscope (SEM) at the Museo Nacional Ciencias Naturales (Madrid, Spain) and a JEOL-JSM-6480 SEM at the Cellular and Molecular Imaging Core Facility (CMIC) of the Faculty of Medicine of the Norwegian
A key for species identification was generated after consideration of the species reported from the northwestern Atlantic (with an asterisk) and other from adjacent geographic regions such as the Gulf of Mexico and the Caribbean (considering recent reviews e.g.
Abbreviations used on the figures: 1st, first chaetiger; al, acicular lobe; ap, antenniform papillae; eg, egg; la, lateral antenna; ma, median antenna; mc, macrotubercle; mi, microtubercle; mo, mouth; no, nuchal organ; pa, palp; tc, tentacular cirrus; vc, ventral cirrus.
Ephesiopsis
Hartman & Fauchald, 1971: 68;
Ephesiopsis guayanae Hartman & Fauchald, 1971.
Body long and slender. Two longitudinal rows of macrotubercles, one pair per segment, absent on first chaetiger. Macrotubercles sessile, with terminal papillae. Two longitudinal rows of microtubercles, one pair per segment, running parallel between macrotubercles. Additionally, papillae arranged in 4–5 transverse rows on dorsum and ventrum. Prostomial and peristomial appendages short, spherical or digitiform. Parapodia from chaetiger 2 with both simple and compound chaetae; hooks on first chaetiger absent or present.
The genus was originally erected and justified by the presence of both simple and compound chaetae in every chaetiger (
An examination of the types of the recently described Ephesiopsis shivae Rizzo, 2009 from Brazil revealed that the specimens do not show the typical generic attributes (
Sphaerodorum
sp. C.–
Ephesiopsis guayanae Hartman & Fauchald, 1971: 68–69, Pl 33, figs A–G.
Holotype:
Ephesiopsis shivae, holotype MZSP883 24°07.637'S 45°51.895'W, 09 Jan 1998, Sta. 6661, 147 m, Santos/São Paulo to Ilha Grande Bay/Rio de Janeiro; paratypes MZSP1031 (2 ind.), 24°07.637'S, 45°51.895'W, 09 Jan 1998, Sta. 6661, 147 m, Santos/São Paulo to Ilha Grande Bay/Rio de Janeiro.
Palps and lateral antennae digitiform, median antenna shorter. Tentacular cirri ellipsoid. Parapodia with 4–6 parapodial papillae; compound chaetae with blades 1.5–2.5 times as long as maximum width on mid-body chaetigers, simple chaetae wider and with angular silhouette; hooks present on first chaetiger.
Measurements and general morphology. Holotype 2.2 mm long, 0.2 mm wide, with 26 chaetigers, divided in two. Body elongated, sub-quadrangular in section, with slightly convex dorsum. Anterior end bluntly rounded, slightly narrowing along posterior segments. Segmentation inconspicuous, tegument with transverse wrinkles. Preserved specimen lacking pigmentation.
Head. Prostomium with five short appendages, including a pair of digitiform palps in ventral-most position, a pair of lateral antennae, similar in shape and size to palps, and a median antenna, shorter (one third) and thinner than lateral antennae (Fig.
Ephesiopsis guayanae,
Tubercles. First chaetiger with two dorsal macrotubercles; microtubercles absent (Fig.
Parapodia. Parapodia sub-conical, increasing in size towards chaetiger 3 (Fig.
Chaetae. First chaetiger with two pairs of hooks, one pair on each parapodia together with elongate simple chaetae. One compound and 2–4 simple chaetae in all chaetigers, arranged in a curved transverse row around acicular lobe (Figs
Pygidium. Pygidium terminal, with one mid-ventral digitiform anal cirrus and a pair of dorsal anal cirri, similar in shape but slightly smaller than macrotubercles (Fig.
Internal features. A pair of eyes anterior to first chaetiger.
Reproductive features. Copulatory organs or eggs not seen in holotype. Paratype with eggs in coelomic cavity.
The paratype, an incomplete gravid female, is larger than holotype, 3 mm long and 0.25 wide, with 44 chaetigers. The specimen from New Jersey is 2 mm long and 0.25 wide. The number and morphology of chaetae showed variation among the material examined. The holotype possessed two pair of hooks on first chaetiger, absent or not seen in the paratype while the specimen from New Jersey had one pair (Fig.
The most remarkable attribute of this species is the presence of simple chaetae, in all parapodia, that are flat and sub-distally widened and have an angular contour. This differs from other members of the long bodied sphaerodorids (Ephesiella and Sphaerodorum), where chaetae, simple or compound respectively, present more rounded edges. In this respect, the holotype and paratypes of E. guayanae show some morphological differences, which, if considered as part of the intraspecific variation, may open a discussion of the legitimacy for the genus. These special, simple, sub-distally widened and flat chaetae were not conspicuous in the paratype. The apparently simple chaetae present in both holo- and paratype do not differ much from those pseudocompound chaetae present in other Ephesiella (e.g. Ephesiella brevicapitis Moore, 1909). With so little material in hand, only two types, it is difficult to conclude on the status of the genus and the identity of the paratype. The species seems not to have been found again, until now.
The chaetae of the specimens collected from sediments of deep New Jersey waters resemble those observed in the paratype of E. guayanae. In every parapodium a group of simple chaetae can be observed, they are not so wide and angular as those present in the holotype, but still they appear to be simple chaetae. Examination of these specimens under SEM revealed a faint oblique mark in the position where an articulation between shaft and blade is expected, and some chaetae seem to be bent at this point. Together these observations suggest that they may be pseudocompound chaetae (Fig.
Surinam, Dutch Guayana, 520–550 m.
From Dutch Guayana to New Jersey, 520–2507 m.
Euritmia
Sardá-Borroy, 1987: 48;
Amacrodorum Kudenov, 1987a: 917–918.
Euritmia hamulisetosa Sardá-Borroy, 1987.
Body short and ellipsoid. Macro- and microtubercles absent; papillae all over body surface and parapodia. Prostomial and peristomial appendages short, spherical or digitiform. Parapodia with simple chaetae, enlarged sub-distally, with serrated cutting edges; hooks absent.
This genus was erected to accommodate a small and atypical species with the body covered by numerous papillae and bearing simple chaetae, Euritmia hamulisetosa Sardá-Borroy, 1987, from southern Spain, and a species previously described as Sphaerodorum, Euritmia capense (Day, 1963), from South Africa (
The genus currently gathers four species, distinguished mainly by the shape and arrangement of dorsal and ventral papillae, the number and arrangement of parapodial papillae and the shape of the chaetae (Table
Comparative features of members of Euritmia, from original descriptions.
Euritmia hamulisetosa | Euritmia capense | Euritmia bipapillatum | Euritmia carolensis sp. n. | |
---|---|---|---|---|
Source |
|
|
|
this study |
Type locality | Cadiz, Spain | Cape Town, South Africa | Alaska, US | South Carolina, US |
Depth | Intertidal | ? | 59 m | 799 m |
Size (length × width) | 0.6×0.125 mm | 2.5×0.8 mm | 2.1×0.5 mm | 0.5×0.2 mm |
Number of chaetigers | 14 | 16 | 16 | 12 |
Prostomial appendages | 3 pairs + median antenna | not distinguishable | two pairs (longer) + median antenna. Lat ant. with spurs | two pairs (longer) + median antenna |
Eyes | two pairs | one pair | one pair | not observed |
Shape of dorsal papillae in mid-body | spherical, all similar in size | spherical, two sizes | two kinds and sizes, hemispherical and ellipsoid | two kinds, hemispherical and ellipsoid |
Number of dorsal papillae in mid-body | four transversal rows | two transverse rows | three transversal rows | three transversal rows |
Ventral papillae | four transversal rows | ? | three transversal rows, elliptical and spherical | two transversal rows |
Parapodial papillae | one dorsal, one ventral | one dorsal, one ventral and three smaller ones on anterior and posterior surfaces | one on anterior surface | none |
Chaetae mophology | serrated, hooked and with distal spine | smooth, hooked | smooth, hooked | smooth or finally serrated, hooked |
Number of chaetae per parapodium | six | ten | four or five | five |
Moreover, a group of species to date considered belonging to Sphaerodoropsis (Group 4, according to
Holotype:
Off Charleston Bump, South Carolina, 799 m.
Body short and ellipsoid. Dorsum with approximately 20 sessile spherical papillae arranged in three transverse rows per segment. Ventrum with 4–6 larger papillae near the parapodial bases. Prostomial and peristomial appendages short and ellipsoidal. Parapodia without papillae; with 4–5 simple chaetae with serrated cutting edges, enlarged sub-distally.
Measurements and general morphology. Holotype 0.5 mm long, 0.2 mm wide, with 12 chaetigers; gravid female. Body ellipsoid, with strongly convex dorsum and flattened ventrum. Epithelium with transversal wrinkles, segmentation not noticeable (Fig.
Head. Head fused to first chaetiger (Figs
Tubercles. Dorsum with three transverse rows of papillae per segment (Figs
Parapodia. Parapodia conical, as long as wide in all chaetigers (Fig.
Chaetae. Large, recurved hooks in first chaetiger absent. All parapodia with 4–5 simple chaetae; blades seemingly smooth on cutting edge and slight curved distal tip (Figs
Pygidium. Pygidium with two dorsolateral pear-shaped tubercles and single midventral digitiform cirrus, longer than lateral cirri (Fig.
Internal features. Muscular pharynx visible though body wall from chaetiger 2–5.
Reproductive features. Copulatory organs not observed. Ovoid eggs measuring 100 µm diameter occupy most of the coelomic cavity.
The two paratypes lack eggs, other features are very similar.
Euritmia carolensis sp. n. is distinguished from other congeners by the presence of dorsal papillae arranged in three transverse rows per segment. Most of these are spherical and similar in size but some in a dorsal-most position are elliptical and larger, without a clear distribution pattern. Euritmia hamulisetosa is provided with spherical papillae, all similar in size, in four transverse rows per segment; E. capense bears two different sizes of spherical papillae each on a single transversal row per segment; and E. bipapillatum bears both hemispherical and elliptical papillae in three transversal rows per segment and with a particular zig-zag arrangement (
The epithet of this species refers to the type locality North Carolina.
North Carolina to New Jersey (US), from 799 to 2014 m.
Sphaerephesia
Fauchald, 1972: 97;
Sphaerephesia longisetis Fauchald, 1972.
Body short and ellipsoid, some species slender. Four or more longitudinal rows of sessile macrotubercles with terminal papillae. Microtubercles absent (?). Papillae over body surface and parapodia. Prostomial and peristomial appendages short, spherical or digitiform. Parapodia with compound chaetae; hooks absent.
There are two species in the genus described as presenting microtubercles (tubercles consisting of a basal collar and a terminal papillae) on the lateral or dorsolateral side of the body, but these differ from those typically present in the long-bodied sphaerodorids (i.e. Ephesiella, Ephesiopsis and Sphaerodoridium).
Holotype:
Sphaerephesia fauchaldi Kudenov, 1987b, holotype
Four longitudinal rows of sessile, bottle-shaped macrotubercles with long digitiform terminal papilla and 3–4 transverse rows of small spherical papillae per segment. Microtubercles absent. Distance between dorsal-most macrotubercles similar to distance between those and lateral ones. Parapodia with ventral cirri nor surpassing length of acicular lobe and four rounded and small papillae. Parapodia with 4–7 compound chaetae, with thin shafts and blades 7–11 times as long as wide.
Measurements and general morphology. Gravid female, 1.5 mm long, 0.2 mm wide, with17 chaetigers. Body elongated, tapering at both ends, slightly flattened dorso-ventrally (wider than high). Dorsum convex and ventrum flattened (Fig.
Sphaerephesia amphorata sp. n., paratypes,
Head. Anterior end bluntly rounded (Fig.
Tubercles. First and last chaetigers with two macrotubercles, sessile, bottle-shaped and provided with a long terminal papilla (Figs
Sphaerephesia amphorata sp. n., paratypes,
Parapodia. Parapodia elongated, sub-conical, increasing in size towards chaetiger 4 and around 2–3 times longer than wide (Figs
Chaetae. Compound chaetae present in all chaetigers, arranged in a curved transverse row (C-shaped) behind acicular lobe and numbering 4–7 per fascicle (Fig.
Pygidium. Pygidium terminal, with mid-ventral digitiform anal cirrus and a pair of dorsal anal cirri, similar in shape to macrotubercles (Fig.
Internal features. Eyes not observed in any specimen. Muscular pharynx runs along three anterior chaetigers.
Reproductive features. Some paratypes and additional specimens examined are gravid females carrying large discoid eggs, 200 µm in diameter that occupy most of the body coelom, from the anterior to the posterior segments; other specimens seem to be filled with sperm. However, ‘copulatory organs’ were not observed in either females or males.
Paratypes varying in size from 0.8 to 1.5 mm and seven to 17 chaetigers. Most features are conserved in this species and all specimens examined regardless the size bear the dorsal macrotubercles with the unusual elongated terminal papillae as long as the macrotubercle. Length of blades vary within fascicles and also along the chaetigers, generally between 7–11 times longer than maximum width.
The most conspicuous and distinct morphological attribute of Sphaerephesia amphorata sp. n. is the presence of dorsal macrotubercles with elongated papillae providing them the characteristic amphora shape, while other described species in the genus have a rounded terminal papilla. Six of the nine nominal Sphaerephesia species share with S. amphorata sp. n. the presence of four rows of macrotubercles with a terminal rounded papilla, several additional papillae on dorsal surface, and falcigers with long blades. These are Sphaerephesia similisetis Fauchald, 1972, Sphaerephesia longisetis Fauchald, 1972, Sphaerephesia chilensis Fauchald, 1974, Sphaerephesia fauchaldi Kudenov, 1987b, Sphaerephesia regularis Böggemann, 2009 and Sphaerephesia hutchingsae Capa & Bakken, 2015. None of the species mentioned share with the new species the number of parapodial papillae; S. fauchaldi, S. hutchingsae, S. longisetis and S. similisetis bear over six parapodial papillae while S. regularis and S. chilensis are provided with one or two parapodial papillae (
Only known from type locality, East of Cape Lookout, North Carolina, United States, North Atlantic, ranging from 580 to 2003 m.
Amphora, is a Greek word that refers to the pottery vases used since the Bronze Age by the Greco-Romans to transport liquids. The shape of these containers resembles the characteristic shape of the dorsal macrotubercles of this species.
Sphaerodoridium
Lützen, 1961: 409–410 (in part),
Sphaerodorum claparedii Greeff, 1866
Body short and ellipsoid. Six or more longitudinal rows of macrotubercles on dorsum, in one transversal row per segment. Macrotubercles stalked and smooth, without terminal papilla. Smaller, stalked tubercles on ventrum. Microtubercles absent. Papillae over body surface and parapodia. Prostomial and peristomial appendages digitiform. Parapodia with only compound chaetae; hooks absent.
Ephesia minuta Webster & Benedict, 1887: 728–729, pl. IV, figs 64–66.
Sphaerodoropsis
minuta
.–
Sphaerodoum
minutum
.–
Sphaerodoridium
minutum
.–
Lectotype:
Palps and lateral antennae digitiform, median antenna shorter and digitiform. Tentacular cirri digitiform. Eyes not observed. Parapodia with three (or four) parapodial papillae; compound chaetae with blades 4–5 times as long as maximum width on mid-body chaetigers.
Measurements and general morphology. Holotype 1.1 mm long, 0.6 mm wide and with 22 chaetigers. Body ellipsoid, ovoid in cross-section, with slightly flattened ventrum and convex dorsum (Fig.
Sphaerodoridium minutum, paratypes
Head. Prostomium with five short appendages, including a pair of digitiform palps in ventral-most position, a pair of digitiform lateral antennae, similar in size and shape as palps, and a digitiform median antenna, shorter than lateral antennae and palps (Fig.
Tubercles. First chaetiger with eight dorsal macrotubercles; following chaetigers each with one transversal row of dorsal macrotubercles increasing to 10–12 tubercles per segment from chaetiger 5 (Fig.
Parapodia. Parapodia sub-conical, increasing in size towards chaetiger 3 (Fig.
Chaetae. All parapodia with 4–7 compound chaetae, arranged in a curved transverse row around acicular lobe (Fig.
Pygidium. Pygidium terminal, with one mid-ventral digitiform anal cirrus projecting beyond parapodia, and one pair of clavate anal cirri, at base on median cirrus (Fig.
Internal features. Specimens are all opaque after fixation and preservation and internal features not observable.
Reproductive features. Copulatory organs or eggs not seen in type specimens.
Most paratypes show small, digitiform anterior appendages but the anterior end is often retracted and these are not easily discernible. This species seems very homogenous regarding the number and arrangement of epithelial tubercles. The exact number of macrotubercles and papillae is, however, difficult to assess in the type material because some of these are detached or because when macrotubercles are inflated and the stalk allows some reorganization, the exact number of tubercles per segment is imprecise. Parapodial papillae in mid-body segments vary between three and four as in some specimens a second papillae can be observed at the base of the posterior parapodial surface (Fig.
The original description is detailed and accurate for most characters, including those more difficult to observe. In most type specimens the dorsal macrotubercles are lost or they fall off when being handled and consequently the total number of tubercles vary from the 10–12 macrotubercles in each transverse row as stated in the original description. Macrotubercles are described as being attached to the body by a “short neck” (
Sphaerodoridium minutum is most similar to S. guerritai Moreira & Parapar, 2015, described from the north eastern Atlantic, having as many dorsal macrotubercles, but S. minutum lacks the characteristic papillae on the macrotubercle’s stalk that S. guerritai possesses, and the latter species has long stalks compared to the short ones in S. minutum. Further, there are clear differences between the two species in number and composition of parapodial papillae. Sphaerodoridium minutum is also similar to Sphaerodoridium evgenovi Gagaev, 2015, Sphaerodoridium kolchaki Gagaev, 2015, and Sphaerodoridium kupetskii Gagaev, 2015, all recently described from the Arctic Ocean, as they all share a similar arrangement and number of macrotubercles (
Sphaerodoridium minutum has similar number of stalked macrotubercles to Clavodorum polypapillata (Hartmann-Schröder & Rosenfeldt, 1988) described from Antarctica, and C. andamanense Bakken, 2002 described from Thailand. In C. polypapillata the original description overlooked stalked macrotubercles (
Sphaerodoridium minutum has been reported with a wide geographic distribution (
The validity and clear delimitation of Sphaerodoridium and Clavodorum Hartman & Fauchald, 1971 has been regarded as doubtful. Several authors pointed out the insubstantial generic differences between the two genera (
This species is known from the New England region of the US. It has been reported from the North Atlantic (e.g.
Sphaerodoropsis
Hartman & Fauchald, 1971: 69;
Sphaerodorum sphaerulifer Moore, 1909.
Body generally short and ovoid, some forms slender. Four or more longitudinal rows of macrotubercles, in one or several transverse rows per segment. Macrotubercles sessile and smooth, without terminal papillae. Microtubercles absent. Papillae over body surface and parapodia. Prostomial and peristomial appendages short, spherical or digitiform. Parapodia with compound chaetae; hooks absent.
Sphaerodoropsis Hartman & Fauchald, 1971: 69–71, pl 34, figs a, b.
Sphaerodoridium
sp. A. –
Holotype:
Sphaerephesia fauchaldi Kudenov, 1987b, holotype
Body ellipsoid, with four longitudinal rows of sessile, rounded to pear-shaped macrotubercles without terminal papillae, per segment. Distance between dorsal-most macrotubercles exceeds distance between those and lateral ones. Parapodia with ventral cirri as long as acicular lobe or slightly shorter and 4–6 rounded, small papillae, sometimes a dorsal one slightly larger. Parapodia with 10–16 compound chaetae, with thin shafts and blades 12–16 times as long as wide.
Measurements and general morphology. Gravid female, 2 mm long, 0.5 mm wide, with 17 chaetigers. Body ellipsoid, slightly flattened dorso-ventrally (wider than high). Tegument with transverse wrinkles and segmentation only barely discernible. Preserved specimen lacking pigmentation.
Head. Anterior end bluntly rounded (Fig.
Sphaerodoropsis corrugata,
Tubercles. First chaetiger with two macrotubercles; rest of chaetigers with four macrotubercles, each arranged in four longitudinal rows along dorsum (Fig.
Parapodia. Parapodia sub-conical, 1–2 times longer than wide (shorter in anterior and posterior most chaetigers), wrinkled (Fig.
Sphaerodoropsis corrugata,
Chaetae. Compound chaetae present in all chaetigers, arranged in a curved transverse row around acicular lobe and numbering 8–12 per fascicle in mid-body chaetigers (Fig.
Pygidium. Pygidium terminal, with mid-ventral digitiform anal cirrus and a pair of dorsal anal cirri, similar in shape to macrotubercles but slightly smaller.
Internal features. Eyes not observed in any specimen; holotype with a pair of reddish anterior spots that may not be eyes, but the nuchal organs. Muscular pharynx runs along chaetigers 3–6.
Reproductive features. Holotype and a few of the additional specimens examined are gravid females carrying large discoid eggs, 200 µm in diameter that occupy most of the body coelom, from the anterior to the posterior segments. “Copulatory organs” not observed.
Specimens measured from 0.6 mm to 3.5 mm. Specimens assigned to this species show some variation in the number and arrangement of the epithelial papillae, probably because there are not easily ascertained in the holotype and were not described in detail in the original description. Larger specimens with approximately 30 papillae present between mid-macrotubercles and 10 between these and the lateral ones in mid-segments (Fig.
Sphaerodoropsis corrugata has not been reported since its original description. Records of this species include off New York state, from 400 to 1500 m (
Sphaerodoropsis elegans Hartman & Fauchald, 1971 originally described from Brazil but also reported from New England, resembles S. corrugata. It also belongs to the Sphaerodoropsis Group 1 sensu
New England, United States, 250–2000 m.
The species reported from the northwestern Atlantic (considered herein as the continental shelf and slope areas off Atlantic Canada and New England) are marked with *.
1 | Long-bodied individual, with two longitudinal rows of spherical macrotubercles (large tubercles) on dorsum with a terminal papilla, and two additional rows of microtubercles (small tubercles with a collar and a terminal papillae) running along the body within the macrotubercles rows | 2 |
– | Body ellipsoid with blunt anterior and posterior ends, dorsal tubercles in more than two longitudinal rows, dorsal microtubercles absent | 5 |
2 | All chaetae simple, robust, with hooked distal ends and rounded edges | Sphaerodorum “flavum” Ørsted, 1843* |
– | At least some chaetae compound or semi compound | 3 |
3 | All parapodia, except in first or second anterior segment, bearing compound and simple chaetae, the latter with angled edges | Ephesiopsis guayanae Hartman & Fauchald, 1971 * |
– | All chaetae, except in first or second anterior segment, compound or semi-compound, often with lost blades | 4 |
4 | Parapodia with 5‒6 papillae each, all arranged at distal end, no erect papilla on dorsal surface of parapodia | Ephesiella macrocirris Hartman & Fauchald, 1971* |
– | Parapodia with two papillae each, not at distal end, one erect papilla on dorsal surface and one on anterior surface of each parapodium | Ephesiella mixta Hartman & Fauchald, 1971* |
– | Parapodia with about 11 papillae each, two on superior margin of parapodia, in addition to others (about nine) distributed randomly over the parapodia | Ephesiella bipapillatum Kudenov, 1987 |
5 | Dorsal macrotubercles, stalked, arranged in six or more longitudinal rows | 6 |
– | Dorsal macrotubercles sessile, arranged in four or more longitudinal rows | 9 |
6 | Lateral antennae without spurs at their bases, ventrum with 10 or more longitudinal rows of papillae in mid-body segments | 7 |
– | Lateral antenna with spurs at their bases, ventrum with up to six longitudinal rows of papillae in mid-body segments | 8 |
7 | Antennae over three times longer than wide, middle antennae often longer than lateral antennae. Ventrum with 10 longitudinal rows of papillae in middle segments, parapodia with 3–6 papillae | Clavodorum mexicanum Kudenov, 1987 |
– | Antennae short, up to three times longer than wide, middle antennae often shorter than lateral. Ventrum with up to 15 longitudinal rows of papillae in middle segments, parapodia with 2–3 papillae | Sphaerodoridium minutum (Webster & Benedict, 1887) * |
8) | Ventrum with papillae arranged in two longitudinal rows, parapodia with a single papilla on the ventral surface | Clavodorum atlanticum Hartman & Fauchald, 1971* |
– | Ventrum with papillae arranged in six longitudinal rows, parapodia with four papillae | Sphaerodoridium lutzeni Kudenov, 1987 |
9 | Dorsal macrotubercles arranged in four longitudinal rows, and one transverse line per segment; chaetae compound | 10 |
– | Dorsal tubercles, considered papillae because of the smaller size compared to macrotubercles of other species, arranged in over 10 longitudinal rows, and approximately two transverse rows per segment; chaetae simple, widened subdistally | Euritmia carolensis sp. n. * |
10 | Dorsal macrotubercles smooth, mainly spherical but some, especially in posterior segments can be pear-shaped | 11 |
– | Dorsal macrotubercles with a terminal papilla | 12 |
11 | Parapodia with 4–6 rounded, small papillae, sometimes a dorsal one slightly larger, 10–16 compound chaetae with blades 12–16 times as long as wide | Sphaerodoropsis corrugata Hartman & Fauchald, 1971* |
– | Parapodia with about 20 papillae and up to 10 chaetae about eight times as long as wide | Sphaerodoropsis vittori Kudenov, 1987 |
12 | Parapodia with a single papilla near de base of the superior edge; chaetae are about eight times as long as wide | Sphaerodoropsis elegans Hartman & Fauchald, 1971* |
– | Parapodia with four papillae; 7–9 chaetae with blades 10–12 times as long as wide | Sphaerodoropsis longipalpa Hartman & Fauchald, 1971* |
We greatly appreciate all the help received from colleagues in several institutions (Australian Museum, Zoologisches Museum Hamburg, Natural History Museum of Los Angeles County, and the Smithsonian National Museum of Natural History) that have facilitated the access to the collection and also sending some material for examination. Special thanks to Angelika Brandt, Anna Murray, Kathrin Philipps-Bussau, Kirk Fitzhugh, Leslie Harris, and Steve Keable. Also to Linda Ward for her help during MC’s stay at the USMN. SEMs were taken in Museo Nacional de Ciencias Naturales de Madrid during a European Commission Taxonomic Initiative SYNTHESYS (ES-TAF-2839), and in NTNU. We are indebted to Juan Moreira for discussions of morphological and species affinities. Juan Moreira and Maite Aguado kindly reviewed the manuscript and made some useful comments for its improvement.