Anthostoma fragile Verrill, 1873: 598–599
Scoloplos fragilis : Verrill 1881: 301
Hartman 1942: 60–61
Brown 1982: 213–227
Scoloplos (Scoloplos) fragilis : Pettibone 1963: 290–292
Haploscoloplos fragilis : Hartman 1944: 340
Leitoscoloplos fragilis : Taylor 1984
New species and records of Orbiniidae (Annelida, Polychaeta) from continental shelf and slope depths of the Western North Atlantic Ocean
Blake, James A.
Zootaxa
2021
2021-02-17
4930
1
1
123
3T3D3
(Verrill, 1873)
Verrill
1873
[151,600,330,357]
Polychaeta
Orbiniidae
Leitoscoloplos
Animalia
14
15
Annelida
species
fragilis
Figures 4–5
Anthostoma fragileVerrill, 1873: 598–599. Scoloplos fragilis: Verrill 1881: 301; Hartman 1942: 60–61, figs. 113-115; Brown 1982: 213–227. Scoloplos (Scoloplos) fragilis: Pettibone 1963: 290–292, fig. 76a–f. Haploscoloplos fragilis: Hartman 1944: 340, pl. 14, fig. 5, pl. 18, fig. 6; 1945: 30, pl. 6, fig. 5; 1951: 76–78, pl. 21, figs. 1–3; 1957: 271–272, p. 25, figs. 1–3; Trott 2004: 280. Leitoscoloplos fragilis: Taylor 1984: 1.19–1.21, fig. 1.18a–g; Mackie 1987: 15–16, fig. 16; Blake et al. 2001: Appendix, 9-1; Fauchald, Granados-Barba & Solís-Weiss 2009: 763; Blake 2017: 18.
Material examined. ( 1,239 specimens) Northeastern USA, Maine, Damariscotta RiverEstuary, Upper Dodge Cove, coll. V. Walker, 05 Aug 1966, 43°59.658′N, 69°33.255′W, intertidal (18, MCZ 161580).— Massachusetts, Woods Hole, coll. G. Sene Silva, 08 Aug 2005, intertidal (1, MCZ 161581).— Massachusetts, New Bedford Harbor, Long-term Monitoring Program, 1999 September-October Survey: ( Upper Harbor): Sta.105-1, 14 Sep 1999, 41°36.407′N, 70°53.983′W, 6.4 m(1, MCZ 161540); Sta.108-3, 06 Oct 1999, 41°40.496′N, 70°54.955′W, 1 m(3, MCZ 161541); Sta.111-1, 05 Oct 1999, 41°40.42′N, 70°54.9′W, 1 m(1, MCZ 161542); Sta.120-1, 18 Nov 1999, 41°13′N, 70°55.08′W, 1 m(5, MCZ 161543); Sta.121-3, 18 Nov 1999, 41°40.154′N, 70°55.003′W, 1.4 m(5, MCZ 161544); Sta.125-3, 29 Sep 1999, 41°40.01′N, 70°55.098′W, 3 m(2, MCZ 161545); Sta.130-3, 01 Oct 1999, 41°39.848′N, 70°55.086′W, 1.8 m(2, MCZ 161546); Sta.134-1, 01 Oct 1999, 41°39.756′N, 70°55.032′W, 2.3 m(46, MCZ 161547); Sta.135-3, 01 Oct 1999, 41°39.753′N, 70°54.936′W, 1.7 m(40, MCZ 161548); Sta.139-1, 29 Sep 1999, 41°39.675′N, 70°55.104′W, 1.4 m(71, MCZ 161549); Sta.140-3, 01 Oct 1999, 41°39.685′N, 70°54.977′W, 3.3 m(30, MCZ 161550); Sta.147, 28 Sep 1999, 41°39.594′N, 70°54.91′W, 1.7 m(2, MCZ 161551); Sta.150-3, 28 Sep 1999, 41°39.513′N, 70°55.087′W, 3.4 m(13, MCZ 161552); Sta.154-2, 28 Sep 1999, 41°39.415′N, 70°55.050′W, 3.4 m(3, MCZ 161553). ( Lower Harbor): Sta.202-1, 06 Oct 1999, 41°39.323′N, 70°55.032′W, 4.7 m(30, MCZ 161554); Sta.207-1, 22 Sep 1999, 41°38.984′N, 70°55.270′W, 1.7 m(147, MCZ 161555); Sta.208-2, 23 Sep 1999, 41°38.981′N, 70°55.022′W, 1.3 m(35, MCZ 161556); Sta.212-2, 24 Sep. 1999, 41°38,826′N, 70°4.906′W, 3.3 m(2, MCZ 161557); Sta.216-2, 22 Sep 1999, 41°38.660′N, 70°55.023′W, 2.2 m(10, MCZ 161558); Sta.218-1, 27 Oct 1999, 41°38.663′N, 70°54.527′W, 9.5 m(26, MCZ 161559); Sta.220-2, 22 Sep 1999, 41°38.507′N, 70°55.141′W, 11.1 m(31, MCZ 161560); Sta.222-1, 23 Sep 1999, 41°38.501′N, 70°54.641′W, 3.1 m(79, MCZ 161561); Sta.224-3, 22 Sep 1999, 41°38.338′N, 70°55.269′W, 10 m(37, MCZ 161562); Sta.226-1, 21 Sep 1999, 41°38.336′N, 70°54.809′W, 3.5 m(39, MCZ 161563); Sta.227-3, 21 Sep 1999, 41°38.330′N, 70°54.537′W, 3 m(71, MCZ 161564); Sta.231-1, 21 Sep 1999, 41°38.166′N, 70°54.874′W, 4.1 m(21, MCZ 161565); Sta.235-3, 20 Sep 1999, 41°38.011′N, 70°55.035′W, 8.8 m(17, MCZ 161566); Sta.237-1, 24 Sep 1999, 41°38.006′N, 70°54.541′W, 6 m(1, MCZ 161567); Sta.240-3, 20 Sep 1999, 41°37.873′N, 70°54.91′W, 10 m(28, MCZ 161568); Sta.242, 20 Sep 1999, 41°37.67′N, 70°54.416’′W, 5.8 m(9, MCZ 161569); Sta.245-3, 19 Sep 1999, 41°37.67′N, 70°54.780′W, 3.4 m(43, MCZ 161570); Sta.249-1, 19 Sep 1999, 41°37.52′N, 70°54.67′W, 2.4 m(17, MCZ 161571); Sta.250- 3, 19 Sep 1999, 41°37.51′N, 70°54.42′W, 8.5 m(10, MCZ 161572). ( Outer Harbor): Sta.306-3, 14 Sep 1999, 41°37.15′N, 70°52.237′W, 2.8 m(12, MCZ 161573); Sta.310-1, 14 Sep 1999, 41°36.407′N, 70°53.983′W, 6.4 m(1, MCZ 161574).— Connecticut, Noank, coll. J.A. Blake, 3 May 1966, 41°19.48′N, 71°59.05′W, intertidal (1, MCZ 161582); Mystic, coll. J.A. Blake, 21 Dec 1965, 41°20.8′N, 71°58.29′W, intertidal (1, MCZ 161579).— New York, Long IslandSound, off Eastchester, Sta. IG25, coll. P.L. Neubert, 28 Oct 1999, 40°52.45′N, 73°45.15′W, 23 m(18, MCZ 161585); Sta.IG 26, 28 Oct 1999, 40°52.20′N, 73°45.66′W, 13 m(115, MCZ 161586); off Throgs Neck, Sta. TN6A, coll. P.L. Neubert, 40°48.6848′N, 73°48.6204′W, 4 m(150, MCZ 161583); Sta.TN12A, 40°48.7949′N, 73°47.1572′W, 16 m(45, MCZ 161584).
Description. Specimen from New BedfordHarbor (NBH) (MCZ 161559) complete, 3.5 cmlong, 1.0 mm wide across thorax with 145 setigers, similar to largest specimens reported by Mackie (1987) from Nantucket, Massachusetts, of 3.9 cmlong, 1.9 mmwide across thorax with 150 setigers. Pettibone (1963) reports larger specimens up 15 cm long, 3 mmwide, and with up to 250 setigers. Body elongate, with thoracic segments short, dorsoventrally flattened, about 4.5 times as wide as long ( Fig. 4A). Thoracic segments of largest specimens with low transverse ridge across dorsum and venter between parapodia. Anterior abdominal segments becoming longer, about 1.5 times as wide as long in anterior segments; middle and posterior abdominal segments crowded, very short. Larger specimens with 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 two setigers ( Fig. 4A–B). Prostomium conical, tapering to pointed tip; nuchal organs curved slits on posterior lateral margin; eyespots absent (but see juvenile morphology below). Peristomium a single smooth achaetous ring dorsally, ventrally encompassing mouth with upper lip formed of two large lobes and lower lip with curved row of eight or more narrow elongate lobes ( Fig. 4B). Proboscis not observed but recorded as a multilobed sac when everted (Pettibone 1963). Thorax with 14–16 setigers (13–16 recorded by Mackie 1987) with abrupt transition to abdominal segments with elongation of neuropodia and decrease in number of neurosetae. Thoracic notopodial postsetal lobes short, triangular in shape along most of thorax ( Fig. 4C), becoming longer in last 1–2 thoracic setigers ( Fig. 4D); all notopodial postsetal lamellae arising directly from body wall. Thoracic neuropodial postsetal lobes short, papillate, arising from broadly rounded base ( Fig. 4C); last 1–3 thoracic neuropodia with extra postsetal lobe and 1–2 short subpodial papillae resulting in last 1–3 thoracic setigers with three short lobes ( Fig. 4D). Abdominal notopodia becoming longer, fingerlike in middle and posterior segments ( Fig. 4E–F). Abdominal neuropodia longer and thickened in middle and posterior segments each narrowing to long narrow apical lobe with a short subterminal lateral cirrus; extra subpodial papillae retained only on first 3–4 abdominal neuropodia ( Fig. 4E), papillae then merging with subpodial flange and continuing over middle and posterior abdominal setigers as large, subpodial flange with 2–3 distinct lobes ( Fig. 4F). Prominent fingerlike interramal cirrus present on last 1–2 thoracic setigers ( Fig. 4D), continuing on anterior and middle abdominal setigers ( Fig. 4E), reduced to low interramal mound or process in posterior neuropodia ( Fig. 4F). Branchiae from setiger 14 or posterior thoracic segment on Connecticutspecimens and larger specimens from New BedfordHarbor, but recorded from abdominal segments by Pettibone (1963) and Mackie (1987); first branchiae on Connecticutand NBH specimens minute, papilliform, becoming full size by about setigers 25–27 or anterior abdominal segments. Anterior branchiae triangular, tapering to rounded apex ( Fig. 4D); branchiae of middle and posterior abdominal segments becoming longer and narrow apex more pointed ( Fig. 4E–F); all branchiae with transverse folds and cilia on inner and outer margins. Notosetae all camerated capillaries; furcate and flail setae not observed; capillaries of thoracic segments numbering about 40 in3–4 irregular rows in thoracic notopodia, reduced to about 15–20 inabdominal segments. Thoracic neurosetae all camerated capillaries with about 50 in3–4 rows; abdominal neurosetae including 3–7 long stiff capillaries with barbs along one edge and 1–2 imbedded aciculae, none observed protruding. Pygidium with two thin lateral anal cirri ( Fig. 5B–C). Variability. The adult specimens encountered here differ from the accounts by Pettibone (1963) and Mackie (1987) in having branchiae from the last one or two thoracic setigers instead of the first abdominal setiger. In addition, the interramal cirrus is typically first present on posterior thoracic segments together with extra subpodial lobes. The interramal cirri are best observed by staining with Shirlastain A; they are more-or-less limited to the last thoracic and middle abdominal setigers. The cirri are reduced to a short, rounded process on small specimens and difficult to see. Juvenile morphology. Juveniles were present in samples from the Throgs Neck (TN) (MCZ 161583) and NBH (MCZ 161564) collections. Several of these specimens were examined in an effort to determine at what size the characters that distinguish L. fragilisfrom local congeners were present. However, unlike the 300-µm-mesh sieve used to collect the L. acutusjuveniles from MassachusettsBay, the sieve size used to separate the fauna from the TN and NBH sediment was 500-µm mesh. As a result, there were fewer juveniles in these samples. However, the smallest sizes observed of L. fragiliswere similar to those of L. acutus. All juveniles have an acutely pointed prostomium; body segments are crowded, especially in posterior setigers. A 28-setiger juvenile from TN is 2.1 mmlong with nine thoracic setigers and branchiae from setiger 10 ( Fig. 5A). Low interramal processes are present on anterior abdominal setigers; these are the anlage of interramal cirri. At this stage, the prostomium is short and triangular. A 32-setiger NBH juvenile is 2.9 mmlong with 11 thoracic setigers with branchiae from setiger 12 ( Fig. 5B, E). At this stage, the prostomium has elongated. The characteristic interramal cirri are observed on a few anterior abdominal setigers as low mounds; in middle and posterior neuropodia short subpodial flanges are irregular in shape due to weakly developed subpodial lobes; posterior setigers are crowded and the characteristic lobed subpodial flange is evident ( Fig. 5E). A 40-setiger NBH juvenile is 3.27 mmlong with 12 thoracic setigers and branchiae from setiger 13 ( Fig. 5C). A few interramal cirri were observed in middle thoracic setigers ( Fig. 5D) and the neuropodia of the same segments were observed to have an irregular subpodial flange due to the presence of a superior subpodial papilla and medial notch. The prostomium has become longer and more pointed. Interestingly, a pair of eyespots was observed on the prostomium of the latter specimen and others of the same size ( Fig. 5F). Such eyespots were not observed on adults. The pygidium of all juveniles consisted two lobes each bearing a long anal cirrus ( Fig. 5B, F). Only camerated capillaries were observed in the noto- and neuropodia of these juveniles.
Remarks. Leitoscoloplos fragilisis most similar to L. robustuswith which it sometimes occurs. The bilobed subpodial flanges of abdominal segments differ from those of L. robustus, which has relatively smooth subpodial flanges (see comments below for L. robustus). The juveniles and adults reported here indicate that the fewest number of thoracic setigers observed is nine on a 28-setiger specimen with branchiae from 10; the largest juvenile reported is a 40-setiger specimen with 12 thoracic setigers and branchiae from setiger 13. The larger adults reported here are up to 150 setigers, 12 cmlong and with a thorax of 14–16 setigers and branchiae from the posteriormost thoracic setigers. The characteristic interramal cirri were present, if only rudimentary, on the smallest juveniles collected and the lobed appearance of the subpodial flange was obvious on the 40-setiger juvenile. These results indicate that the most important characters required to identify L. fragilisare evident early in development.
Biology. Brown (1982)described some aspects of the distribution and biology of L. fragilison a tidal flat in Delaware, USA. The species lives in the upper 15 cmof sediments having sand-size particles (1.36–1.44 mean phi Ø). Salinity at the site ranged from 28–30 PSU and a wide range of water temperatures from 2.0°C in December to 28°C in August. At the study site, a wave-swept sand bar, the species occurred on slopes, ridges, and troughs with the highest densities on slopes. At least three age classes were found, with reproductive maturity occurring after two years; the smallest specimens occurred in the August or mid-summer samples. Gametogenesis and reproductive biology were not investigated; egg diameters were not provided and cocoons with eggs or larvae were not observed. In New BedfordHarbor, Massachusetts, the highest densities of L. fragilisoccurred in lower portions of the Upper Harborand throughout the Lower Harborat stations having high sand and gravel content of 50% or greater ( Blake et al. 2001).
Distribution. Eastern Canadato Florida; Gulf of Mexico; intertidal to shallow subtidal.
3069842367
1966-08-05
MCZ
V. Walker
United States of America
43.9943
Upper Dodge Cove
1
-69.55425
Damariscotta River
14
15
MCZ 161580
1
Maine
3069842972
2005-08-08
MCZ
G. Sene Silva
United States of America
Woods Hole
14
15
MCZ 161581
1
Massachusetts
3069842830
1999-09-14
MCZ
Sta.
United States of America
New Bedford Harbor
6
41.606785
September-October Survey
1
-70.89972
Long-term Monitoring Program
14
15
MCZ 161540
1
Massachusetts
3069842512
1999-10-06
MCZ
United States of America
1
41.674934
Sta.
1
-70.91592
14
15
MCZ 161541
1
3069842782
[395,1208,869,898]
1999-10-05
MCZ
United States of America
1
41.673668
Sta.
70
-70.915
14
15
MCZ 161542
1
3069842560
1999-11-18
MCZ
United States of America
1
41.216667
Sta.
925
-70.918
14
15
MCZ 161543
1
3069842302
1999-11-18
MCZ
United States of America
1
41.669235
Sta.
1
-70.91672
14
15
MCZ 161544
1
3069842598
[325,1153,941,970]
1999-09-29
MCZ
United States of America
3
41.666832
Sta.
9
-70.9183
14
15
MCZ 161545
1
3069842550
1999-10-01
MCZ
United States of America
2
41.664135
Sta.
1
-70.9181
14
15
MCZ 161546
1
3069842612
1999-10-01
MCZ
United States of America
2
41.6626
Sta.
1
-70.9172
14
15
MCZ 161547
1
3069842812
[327,1215,1013,1042]
1999-10-01
MCZ
United States of America
2
41.66255
Sta.
1
-70.9156
14
15
MCZ 161548
1
3069842951
1999-09-29
MCZ
United States of America
1
41.66125
Sta.
1
-70.9184
14
15
MCZ 161549
1
3069842688
1999-10-01
MCZ
United States of America
3
41.661415
Sta.
1
-70.91628
14
15
MCZ 161550
1
3069842806
[401,1222,1085,1114]
1999-09-28
MCZ
United States of America
2
41.6599
Sta.
7
-70.91517
14
15
MCZ 161551
1
3069842500
1999-09-28
MCZ
United States of America
3
41.65855
Sta.
1
-70.91811
14
15
MCZ 161552
1
3069842377
1999-09-28
MCZ
United States of America
3
41.656918
Lower Harbor
1
-70.9175
Sta.
14
15
MCZ 161553
1
3069842504
1999-10-06
MCZ
United States of America
5
41.655384
Sta.
1
-70.9172
14
15
MCZ 161554
1
3069842416
[263,1202,1193,1222]
1999-09-22
MCZ
United States of America
2
41.649734
Sta.
1
-70.921165
14
15
MCZ 161555
1
3069842468
1999-09-23
MCZ
United States of America
1
41.649685
Sta.
1
-70.91703
14
15
MCZ 161556
1
3069842753
1999-09-24
MCZ
United States of America
3
41.6471
Sta.
1
-70.081764
14
15
MCZ 161557
1
3069842502
[451,1376,1265,1294]
1999-09-22
MCZ
United States of America
2
41.644333
Sta.
1
-70.91705
14
15
MCZ 161558
1
3069842818
1999-10-27
MCZ
United States of America
10
41.644382
Sta.
1
-70.90878
14
15
MCZ 161559
1
3069842456
1999-09-22
MCZ
United States of America
11
41.641785
Sta.
1
-70.919014
14
15
MCZ 161560
1
3069842859
1999-09-23
MCZ
United States of America
3
41.64168
Sta.
1
-70.91068
14
15
MCZ 161561
1
3069842305
[260,1145,1373,1402]
1999-09-22
MCZ
United States of America
10
41.638966
Sta.
1
-70.92115
14
15
MCZ 161562
1
3069842624
1999-09-21
MCZ
United States of America
4
41.638935
Sta.
1
-70.91348
14
15
MCZ 161563
1
3069842698
1999-09-21
MCZ
United States of America
3
41.638832
Sta.
1
-70.90895
14
15
MCZ 161564
1
3069842944
[327,1216,1445,1474]
1999-09-21
MCZ
United States of America
4
41.6361
Sta.
1
-70.914566
14
15
MCZ 161565
1
3069842639
1999-09-20
MCZ
United States of America
9
41.63352
Sta.
1
-70.91725
14
15
MCZ 161566
1
3069842708
1999-09-24
MCZ
United States of America
6
41.633434
Sta.
1
-70.90902
14
15
MCZ 161567
1
3069842566
[415,1287,1517,1546]
1999-09-20
MCZ
United States of America
10
41.631218
Sta.
7
-70.91517
14
15
MCZ 161568
1
3069842382
1999-09-20
MCZ
United States of America
6
41.627834
Sta.
14
15
MCZ 161569
1
3069842516
1999-09-19
MCZ
United States of America
3
41.627834
Sta.
9
-70.913
14
15
MCZ 161570
1
3069842831
[452,1319,1589,1618]
1999-09-19
MCZ
United States of America
2
41.62533
Sta.
11
-70.91116
14
15
MCZ 161571
1
3069842451
1999-09-19
MCZ
Outer Harbor
United States of America
9
41.625168
Sta.
11
-70.907
14
15
MCZ 161572
1
3069842650
1999-09-14
MCZ
United States of America
3
41.619167
Sta.
9
-70.87061
14
15
MCZ 161573
1
3069842941
1999-09-14
MCZ
United States of America
6
41.606785
Sta.
1
-70.89972
14
15
MCZ 161574
1
3069842891
1966-05-03
MCZ
J. A. Blake
United States of America
41.324665
Noank
11
-71.98417
14
15
MCZ 161582
1
Connecticut
3069842709
[259,1278,1733,1762]
1965-12-21
MCZ
J. A. Blake
United States of America
41.34667
Mystic
92
-71.9715
14
15
MCZ 161579
1
3069842356
1999-10-28
MCZ
Sta. IG & P. L. Neubert
United States of America
23
40.87417
Eastchester
11
-73.7525
Long Island
14
15
MCZ 161585
1
New York
3069842537
[375,1229,1805,1834]
1999-10-28
MCZ
United States of America
13
40.87
Sta.
11
-73.761
14
15
MCZ 161586
1
3069842347
MCZ
Sta. TN & P. L. Neubert
United States of America
4
40.811413
Throgs Neck
1
-73.81034
14
15
MCZ 161583
1
3069842578
MCZ
United States of America
16
40.813248
Sta.
1
-73.78595
14
15
MCZ 161584
1
3069842940
Lower Harbor
Upper Harbor
18
19
1
Bedford