Scoloplos verrilli, Blake, 2021

Blake, James A., 2021, New species and records of Orbiniidae (Annelida, Polychaeta) from continental shelf and slope depths of the Western North Atlantic Ocean, Zootaxa 4930 (1), pp. 1-123 : 54-59

Scoloplos verrilli new species

Figures 25–27

urn:lsid:zoobank.org:act:72DA560F-2F73-4C2A-9D8D-D7BBE81DBA43

Scoloplos (Scoloplos) armiger: Pettibone 1963: 292–293 , fig. 76 h–I; Trott 2004: 280. Not Müller, 1776.

Scoloplos armiger: Blake et al. 1998 : C-1, C-2 (in part). Not Müller, 1776.

Material examined. (88 specimens) Northeastern USA, Massachusetts Bay, MWRA Harbor and Outfall Monitoring Program. 1995 August Survey : Sta. FF-13, 42°19.19′N, 70°49.38′W, 19 m, holotype ( MCZ 161633 ) and 4 paratypes ( MCZ 161634 ) . Sta. FF-9, 42°18.75′N, 70°39.40′W, 49 m, 11 paratypes ( MCZ 161631 ) . Sta. FF-10, 42°24.84′N, 70°52.72′W, 27 m (1, MCZ 161632 ) .— 1992August Survey: Sta. NF-1, 42°20.35′N, 70°50.51′W, 42 m (2, MCZ 161614 ) . Sta. NF-5, 40°25.62′N, 70°50.03′W, 28 m (2, MCZ 161615 ) . Sta. NF-6, 42°24.30′N, 70°49.99′W, 31 m (2, MCZ 161616 ) . Sta. NF-7, 42°24.60′N, 70°48.89′W, 32 m (5, MCZ 161617 ) . Sta. NF-11, 42°23.39′N, 70°50.25′W, 31 m (1, MCZ 161619 ) . Sta. NF-12, 42°23.40′N, 70°49.83′W, 33 m (6, MCZ 161620 ) . Sta. NF-13, 42°23.40’N, 70°49.35’W, 33 m (1, MCZ 161621 ) . Sta. NF-15, 42°22.93′N, 70°49.67′W, 32 m (3, MCZ 161622 ) . Sta. NF-19, 42°22.30′N, 70°48.30′W, 32 m (5, MCZ 161623 ) . Sta. FF-4, Rep. 2, 42°117.30′N, 70°25.50′W, 48 m ( MCZ 161624 ) . Sta. FF-9, Rep. 1, 42°18.75′N, 70°39.40′W, 48 m (9, MCZ 161625 ) . Sta. FF-9, Rep. 2, 42°18.75′N, 70°39.40′W, 48 m (9, MCZ 161626 ) . Sta. FF-10, Rep. 3, 42°24.84′N, 70°52.72′W, 27 m (2, MCZ 161618 ) . Sta. FF-12, Rep. 1, 42°23.40′N, 70°53.98′W, 22 m (1, MCZ 161627 ) ; Rep. 2, 2 paratypes ( MCZ 161628 ) ; Rep. 3, 4 paratypes ( MCZ 161629 ) . Sta. FF-13, Rep. 1, 42°19.19′N, 70°49.38′W, 19 m (9, MCZ 161630 ) .— 1996 August Survey: Sta. MF-02, 42°20.331′N, 70°49.69′W, 30 m (3, MCZ 161647 ) . Sta. MF-07, 42°24.60′N, 70°48.89′W, 33 m (2, MCZ 161648 ) . Sta. MF-08, 42°24.00′N, 70°51.81′W, 32 m (3, MCZ 161649 ) . Sta. MF-09, 42°23.99′N, 70°50.69′W, 29 m (3, MCZ 161650 ) . Sta. MF-10, 42°23.57′N, 70°50.69′W, 35 m (2, MCZ 161651 ) . Sta. MF-14, 42°22.70′N, 70°50.26′W, 29 m (1, MCZ 161652 ) . Sta. MF-20, 42°22.69′N, 70°50.69′W, 28 m, 4 paratypes ( MCZ 161653 ) . Sta. MF-22, 42°20.87′N, 70°48.90′W, 36 m (1, MCZ 161654 ) . Sta. NF-15, 42°22.93′N, 70°49.67′W, 32 m; (1, MCZ 161655 ) . Sta. NF-19, 42°22.30′N, 70°48.30′W, 32 m (4, MCZ 161656 ) . Sta. NF-24, Rep. 1, 42°22.83′N, 70°48.10′W, 37 m (1, 161657); Rep. 2, 12 paratypes ( MCZ 161658 ) . Rep. 3, 19 paratypes ( MCZ 161659 ) . Sta. FF-5, Rep. 3, 42°08.0084′N, 70°25.35′W, 61 m (1, MCZ 161635 ) . Sta. FF-9, Rep. 1, 42°18.75′N, 70°39.40′W, 49 m (2, MCZ 161636 ) ; Rep. 2 (4, MCZ 161637 ) . Sta. FF-10, Rep. 1, 42°24.84′N, 70°52.72′W, 27 m (5, MCZ 161638 ) ; Rep. 2, 4 paratypes MCZ 161639 ); Rep. 3 (1, MCZ 161640 ) . FF-Sta. 12, Rep. 1, 42°23.40′N, 70°49.83′W, 22 m, 15 paratypes ( MCZ 161641 ) ; Rep. 2 (5, MCZ 161642 ) ; Rep. 3 (5, MCZ 161643 ) . Sta. FF-13, Rep. 1, 42°19.19′N, 70°49.38′W, 19 m (3, MCZ 161644 ) ; Rep. 2, 5 paratypes ( MCZ 161645 ) ; Rep. 3 (3, MCZ 161646 ) .— 1997 August Survey: Sta. FF-9, Rep. 1, 42°18.75′N, 70°39.40′W, 49 m (2, MCZ 161660 ) . Sta. FF-10, Rep. 1, 42°24.84′N, 70°52.72′W, 27 m (5, MCZ 161661 ) . Sta. FF-12, Rep. 1, 42°23.40′N, 70°49.83′W, 22 m (3, MCZ 161662 ) ; Rep. 2 (5, MCZ 161663 ) ; Rep. 3 (3, MCZ 161664 ) . Sta. MF-2, 42°20.31′N, 70°49.69′W, 29 m (1, MCZ 161665 ) . Sta. MF-

9, 42°23.99′N, 70°50.69′W, 35 m (2, MCZ 161666 ) . Sta. MF-10, 42°23.57′N, 70°59.29′W, 34 m (5, MCZ 161667 ) . Sta. MF-12, Rep. 3 42°23.40′N, 70°49.83′W, 34 m (2, MCZ 161668 ) . Sta. MF-20, 42°23.69′N, 70°50.69′W, 28 m, 1 paratype ( MCZ 161669 ) .

Description. A large species; holotype complete, partially coiled, 175 setigers, 42 mm long and 0.8 mm wide across thorax; paratype (MCZ 161634) with ca. 200 setigers, 42.2 mm long, 1.3 mm across thorax; both with 17 thoracic setigers and branchiae from setiger 14. Other large specimens with 16–17 thoracic setigers and branchiae from setigers 13–14. Thoracic segments dorsoventrally flattened, often with 6–8 anterior thoracic segments swollen dorsally due to location of internal retracted pharynx; Thoracic segments short, about six times wider than long ( Fig. 25A ), transitioning to abdominal segments at least 2½ times longer than thoracic segments ( Fig. 27 A–B). Transition from thorax to abdomen denoted by appearance of elongate, enlarged neuropodium, simple at first, becoming longer and with apex split over successive segments. Color in alcohol light tan; subpodial flanges of middle and posterior abdominal neuropodia with a few internal glands retaining stain red with Rose Bengal and reddish brown with Shirlastain A.

Pre-setiger region triangular, wider than long, as long as first 2½ setigers ( Fig. 25 A–C). Prostomium conical, tapering to pointed tip ( Figs. 25 A–C; 27A–B); nuchal organs semi-circular slits on posterior lateral margin ( Fig. 25C ); eyespots absent. Peristomium as long as first setiger, with a single smooth annular ring dorsally ( Fig. 25A ), surrounding mouth ventrally, forming upper and lower lips ( Fig. 25B ); upper lip of mouth with two narrow transverse curved lobes; ventral lip of mouth with 8–10 narrow elongate lobes. Proboscis with three long, narrow lobes seen when everted ( Fig. 27B ).

Anterior thoracic notopodia with digitiform postsetal lobe, base arising directly from body wall; lobe triangular, short at first ( Fig. 26A ), then becoming longer, narrow in posterior thoracic segments ( Fig. 26B ). Thoracic neuropodia with broad base, bearing medial postsetal lobe, short and rounded at first ( Fig. 26A ), then becoming conical in shape in posterior thoracic setigers; posterior thoracic neuropodia from setigers 14–15 developing a second short postsetal lobe and a short subpodial papilla ( Fig. 26B ). Transition to abdominal segments abrupt, with neuropodia becoming thick, elongate and with fewer neurosetae ( Figs. 25A , 26C ); notopodial postsetal lobes becoming narrow and elongate along rest of body ( Figs. 26 C–E, 27E). Abdominal neuropodia of anterior and middle setigers elongate, narrow, divided into two parts separated by notch ( Fig. 26 C–D); medial lobe long, pointed; ventral lobe shorter, rounded apically, directed laterally; ventral lobe lost in far posterior neuropodia that taper to a pointed tip ( Fig. 26E ). Interramal cirrus absent, but distinct low, rounded interramal swelling bearing cilia present at base of notopodium ( Fig. 26 B–E). Abdominal neuropodia with narrow subpodial flange throughout ( Figs. 26 D–E, 27E); anteriormost abdominal neuropodia with subpodial flange transitioning from second postsetal lobe of thoracic neuropodia ( Fig. 27C ); a single subpodial papilla retained on a few anterior abdominal segments. Subpodial flanges of middle and posterior abdominal setigers with few large internal pigmented glands.

Branchiae from thoracic setiger 13 or 14; branchiae short, triangular at first ( Figs. 25A , 26B ), becoming longer, leaflike; branchiae full size by first abdominal segment ( Fig. 26C ). Branchiae of middle and posterior setigers elongate, narrow, weakly asymmetrical ( Figs. 26 D–E, 27E). Each branchia thickly ciliated along lateral and medial margins ( Figs. 26 C–E, Fig. 27E ).

Thoracic notosetae numerous thick, long, camerated capillaries arranged in 2–3 rows. Thoracic neurosetae with about four rows of capillaries and a few hooked uncini first occurring as a group in ventral most part of fascicle and then over subsequent setigers extending dorsally as single curved row of 7–8 uncini between third and fourth row of capillaries ( Fig. 25D ). Uncini difficult to observe among more numerous capillaries, always shorter and observed in ventral part of fascicle. Uncini best observed in first 7–10 setigers, becoming reduced to 3–4 uncini in lower part of setal fascicle; either absent or not observed in posterior thoracic setigers. Individual uncini with shafts smooth on convex side, tapering to narrow, rounded tip; concave side of shaft flattened, bearing barbs along most of shaft ( Fig. 25E ). Abdominal notosetae thin, camerated capillaries and 1–2 furcate setae. Furcate setae with unequal tynes; long tyne with blunted tip and apical notch; shorter tyne with narrow rounded tip; each with row of thin needles extending medially ( Fig. 25 F–G). Abdominal neurosetae with up to 4–6 thin capillaries, each with short barbs along one edge, and 1–2 narrow curved aciculae, sometimes protruding, with rounded tip ( Fig. 26D inset). Flail setae not observed.

Pygidium short, with two dorsal lobes each subdivided into 2–3 parts and two large ventrolateral lobes surrounding anal opening; with two long anal cirri arising dorsally ( Figs. 26F , 27D ).

Remarks. Scoloplos verrilli n. sp. was commonly collected in Massachusetts Bay as part of the long-term monitoring program associated with an offshore outfall. The species differs from S. pettiboneae n. sp. and S. pseu- doarmiger n. sp., which are also present offshore Massachusetts, in having only a few uncini in thoracic neuropodia instead of numerous uncini in multiple rows. Along the U.S. Atlantic coast, S. verrilli n. sp. from off New England is most similar to S. papillatus n. sp., which occurs in upper slope sediments off North Carolina. Details regarding the differences between these two species were reviewed in the account for S. papillatus n. sp. (see above).

Scoloplos armiger sensu Pettibone (1963) is believed to be the same as S. verrilli n. sp. because she noted that only a few spines, together with numerous capillaries, were present in thoracic neuropodia. However, her account suggests that other species were likely present in her material as well.

Etymology. This species is named for Professor Addison Emery Verrill, eminent 19 th century zoologist at Yale University. Professor Verrill’s surveys and subsequent publications on the marine invertebrates of offshore New England included descriptions of numerous polychaetes including orbiniids. Currently three common species of Leitoscoloplos and one species of Phylo that occur along the U.S. Atlantic coast were originally described by Verrill (1873).

Distribution. Massachusetts Bay, 19– 51 m.

Genus Leodamas Kinberg, 1866

Type-species: Leodamas verax Kinberg, 1866 , by monotypy.

Synonym: Branchethus Chamberlin, 1919b . Type-species: Branchethus latum Chamberlin, 1919b , by monotypy. Fide Hartman 1957.

Diagnosis. (after Blake 2017). Prostomium pointed on anterior margin, usually prolonged; most species with a single achaetous peristomial segment; immature adults of some species with two achaetous peristomial segments and adults of at least one species with vague indication of two achaetous segments. Branchiae single or multiple branches, either from anterior thoracic setigers 4–7 or from posterior thoracic setigers or first abdominal setigers. Posterior thoracic setigers with 0–2 postsetal lobes and 0–2 subpodial lobes, never more than four lobes of both types combined; lobes not forming ventral fringes. Thoracic neuropodial uncini large, conspicuous, arranged in one to many distinct vertical rows, with accompanying capillaries few or entirely lacking; heavy spear-like spines and bristle-topped setae absent. Abdominal neuropodia with projecting aciculae, either thin and inconspicuous or large and curved apically. Abdominal noto- or neuropodial flail setae present or absent.

Remarks. Blake (2017) redefined Leodamas and referred 29 species to the genus; two additional species were subsequently qdescribed by Sun et al. (2018) from the East China Sea and Blake (2020) from the South China Sea. Blake (2017) divided the species into two groups: (Group A) species with branchiae from an anterior thoracic setiger (4–7) and thoracic neuropodial uncini typically in three or more rows and (Group B) species with branchiae from a posterior thoracic or anterior abdominal setiger (12–29) and with thoracic neuropodial uncini typically in 1–2 rows. The species assigned to Group B were previously referred to the genus Scoloplos , but redefined as a separate group of Leodamas species by Blake (2017). Only species belonging to Group A were found in the present study.

Based on Blake (2017, 2020) and Sun et al. (2018), 21 species of Leodamas are known, of which only four have been reported from depths greater than 500 m. In the present study, three additional species have been found: (1) L. cuneatus n. sp. in lower slope depths of New England and mid-Atlantic sites off New Jersey and Delaware, (2) L. mucronatus n. sp. from upper slope depths off South Carolina, and (3) L. notoaciculatus n. sp. from inner shelf depths off New Jersey. The two deep-water species have unusual pre-setal morphology.

Figures

FIGURE 25. Scoloplos verrilli n. sp. Paratypes (MCZ 161628): A, anterior end, dorsal view; B, anterior end, ventral view; C, anterior end, left lateral view; D, diagram of thoracic setiger and rows of capillaries and uncini (not to scale); E, thoracic neuropodial uncinus; F, G, furcate setae.

FIGURE 26. Scoloplos verrilli n. sp. Paratypes (MCZ 161628): A, thoracic setiger 5, anterior view; B, thoracic setiger 15, posterior view; C, anterior abdominal setiger 20, posterior view; D, middle abdominal setiger, posterior view; E, far posterior abdominal setiger, posterior view; F, pygidium, dorsal view.

FIGURE 27. Scoloplos verrilli n. sp. A, holotype, anterior end, right lateral view; B, paratype, anterior end, right lateral view; C, paratype, detail of thoracic-abdominal transition, arrows denote subpodial lobes; D, holotype, pygidium, left lateral view; E, middle abdominal setiger, posterior view. A, D, holotype (MCZ 161633); B–C, E, paratype (MCZ 161634). All stained with Shirlastain A.