Pherusa plumosa ( Müller, 1776 )

Salazar-Vallejo, Sergio I., 2014, Revision of Pherusa Oken, 1807 (Polychaeta: Flabelligeridae), Zootaxa 3886 (1), pp. 1-61 : 9-13

Pherusa plumosa ( Müller, 1776) restricted

Figure 1

Amphitrite plumosa Müller, 1776:216 .— Fabricius, 1780:288–289.— Müller, 1789:16–17, Pl. 90, Figs 1–2 .— Grube, 1850:321.

Trophonia? goodsiri Johnston, 1840:371–373 , Pl. 11, Figs 1–10 .

Siphonostomum plumosum . — Rathke, 1842:84–92, Pl. 6, Figs 1–7 (syn.), 1843:208–211, Pl. 11, Figs 1–2 .

Flemingia plumosa .— Johnston, 1846:447 (n. comb.).

Trophonia plumosa .— Johnston, 1865:224–225, Pl. 19, Figs 1–10 (same descr. & illust. for T. goodsiri ).

Stylarioides plumosa .— Fauvel, 1907:20, 1909:6, 1927:116–117, Figs 41a–g (partim).— McIntosh 1915:89–96, Pl. 89, Fig. 1 , Pl. 95, Figs 11–11b Pl. 96, Figs 1–1a , Pl. 104, Figs 1–1d (syn.).— Rioja-LoBianco, 1931:96–98, Pls 28–29.—Wesenberg- Lund, 1950:35.— Kirkegaard, 1959:43 (partim).

Pherusa arctica Støp-Bowitz, 1948a:20–22 , Fig. 4 .

Pherusa plumosa .— Oken, 1815:377, Pl. 4, Sect. 6, Fig. 2 .— Cunningham & Ramage, 1888:674–676, Pl. 46, Fig. 39A–B (Anat.).— Støp-Bowitz, 1948a:13–18, Fig. 2 (syn., partim), 1948b:33–36, Fig. 12 .— Eliason, 1962:62–64, Fig. 8 (syn., neurochaetal variation).— Jirkov & Filippova, 2001:362–363, Figs 1–3 (syn.).

Type material. Northwestern Atlantic Ocean. Greenland. Neotype ( USNM 23257 ), 1.9 km NW of Conical Rock, Igannaq (76º05'07.12" N, 68º41'27.57" W), NW Greenland, 46-110 m, 22 Jul. 1940, R.A. Bartlett, coll.

Additional material. Northwestern Atlantic Ocean. Greenland. Anterior fragment ( USNM 50948), off Little Hellefiske Bank, Western Greenland, Sta. 29F (64°54' N, 53°38' W), 79–85 m, 18 Aug. 1968, Blake & Dean, coll. (20 mm long, 5 mm wide, cephalic cage 10.5 mm long, 20 chaetigers; dorsal papillae on anterior chaetigers long, tapered, mostly without sediment grains, 4–5 series per segment; neurohooks from chaetiger 4, 4 per fascicle; notochaetae as long as ½ body width). Anterior fragment ( ZMUC 1793), Skovfjord, Greenland, RV Rink, Sta. 143 (no further data), 65–90 m, 3 Sep. 1912 (44 mm long, 8 mm wide, cephalic cage 15 mm long, 26 chaetigers; dorsal papillae on anterior chaetigers rounded, short, with fine sand particles, 4–5 series per segment; neurohooks from chaetiger 4, 4, then 5–6 per fascicle, 4 again towards the end of the fragment; notochaetae as long as ½ body width). One specimen ( ZMUC 1794), Lindenowfjord, Greenland, 400–600 m, 28 Jul. 1935, Bertelsen, coll. (50 mm long, 5 mm wide, cephalic cage 10 mm long, 52 chaetigers (regenerating from chaetiger 35); dorsal papillae on anterior chaetigers rounded with fine mud particles, 4–5 series per segment; neurohooks from chaetiger 4, 3–4 per fascicle, reduced to 2 in medial and posterior chaetigers; notochaetae as long as ½ body width). Canada. Four anterior fragments, damaged ( USNM 1609), off Newfoundland, RV Albatross, Cruise 1885, Sta. 2458 (46°48' N, 52°34' W), 163 m, 2 Jul. 1885 (12 mm wide; 7–9 notochaetae in chaetiger 10; all with neurohooks from chaetiger 4, including the smallest fragment with 3 mm body width; 4–7 neurohooks in anterior chaetigers, 3–5 in posterior ones per fascicle, body-size dependent; 4–5 series of large papillae on anterior chaetigers; notochaetae as long as ½ body width). One specimen ( USNM 8940), anterior fragment, many chaetae broken, off Halifax, Nova Scotia, RV Speedwell, Sta. 98-99, 33 m, 15 Sep. 1817, A.E. Verrill, id. as Trophonia affinis . Two specimens ( USNM 8952), Bedford Basin, Nova Scotia, RV FishHawk, Sta. 53, 64 m, 25 Aug. 1877, A.E. Verrill, id. as T. aspera (one with anterior end exposed, chaetae previously trimmed, used for description). One specimen ( USNM 15468), anterior fragment, outside of Hebron, Labrador, 110 m, gravel, 25 Aug. 1908. One specimen ( USNM 15469), anterior fragment, Nain, Labrador, 132 m, mud, 18 Aug. 1908. Three specimens ( USNM 23259), one anterior, two medial fragments, Kneeland Bay, Frobischer Bay, 31 m, 26 Aug. 1942, E.C. Rigby, coll. (dried out, body wall and chaetae dark brown). One specimen ( USNM 23263), without posterior end, Soak Point, Hebron Fjord, Labrador, 24 m, rock, pebble, sand, 31 Aug. 1949, D.C. Nutt, coll. One specimen ( USNM 1131519) broken in two parts, off Resolute, Cornwallis Island, Sta. 62-4003, B-10 (74°39.1' N, 94°16.8' W), 30 m, 9 Jul. 1962 (35 mm long, 6 mm wide, cephalic cage 10.5 mm long, 26 chaetigers; cephalic cage delicate; 11–12 notochaetae in medial chaetigers). One specimen ( USNM 1131520), broken in three parts, most papillae eroded, slightly dried out, chaetae reddish, Labrador, RV Resolute, Sta. 704 B7b (56º43' N, 81º38' W), 22 m, mud, 24 Jul. 1955 (86 (24+33+29) mm long, 4.5 mm wide, cephalic cage 16 mm long, 11 notochaetae in chaetiger 10). Northeastern United States. Five specimens ( USNM 8945), two complete, three without posterior ends, flaccid, Casco Bay, SE Monhegan, Maine, 132 m, 13 Sep. 1873, A.E. Verrill, id. as T. aspera (30–63 mm long, 3–6 mm wide, cephalic cage 5.5–12.5 mm long, 64–75 chaetigers, 7-10 notochaetae in chaetiger 10). One specimen ( USNM 8947), breaking in two, RV FishHawk, Sta. 170-171, 165 m, 24 Aug. 1878, A.E. Verrill id. as T. aspera (33 mm long, 3.4 mm wide, cephalic cage 8.5 mm long, 63 chaetigers, 7 notochaetae in chaetiger 10). One specimen ( USNM 8948), cephalic cage broken, Massachusetts Bay, US FishHawk, Sta. 205, 77 m, 16 Sep. 1878, A.E. Verrill, id. as T. aspera (50 mm long, 4 mm wide, cephalic cage 6 mm long, 74 chaetigers, 8 notochaetae in chaetiger 10). Two specimens ( USNM 8949), anterior fragments, RV Speedwell, Sta. 154, 70 m, 15 Aug. 1878, A.E. Verrill, id. as T. aspera . One specimen ( USNM 8955), broken in two, off Salem, Massachusetts, RV FishHawk, Sta. 32-33, 165 m, A.E. Verrill, id. as T. aspera (42 mm long, 4 mm wide, cephalic cage 10 mm long, 62 chaetigers, 8 notochaetae in chaetiger 10). One specimen ( USNM 15384), partially dehydrated, many papillae eroded, Massachusetts Bay, RV Speedwell, Sta. 219, 59 m, 18 Sep. 1878, A.E. Verrill, id. as T. aspera . Northeastern Atlantic Ocean. Germany, Baltic Sea. Three specimens ( USNM 288), very damaged, Kielerbucht, K. Moebius, coll., no further data (complete 32 mm long, 4 mm wide, cephalic cage 10 mm long, 55 chaetigers, 8 notochaetae in chaetiger 10). France. Two specimens ( MNHN 457), complete, tunic removed almost completely, Tatihou, Aug. 1895, P. Fauvel, coll. (72–81 mm long, 6 mm wide, cephalic cage 10–11 mm long, 66–69 chaetigers; anterior chaetigers without a mass of sediment grains; chaetiger 10 with 8–10 noto- and 4–5 neurochaetae). Four specimens ( MNHN 507), three complete, Tatihou, May–Jul. 1895, P. Fauvel, coll. (complete ones 55–69 mm long, 4.5–5.5 mm wide, cephalic cage 9–10 mm long, 62–72 chaetigers; anterior chaetigers without a mass of sediment grains; chaetiger 10 with 7–8 noto- and 3–4 neurochaetae).

Description. Neotype (USNM 23257) damaged, apparently fixed in ethanol, without posterior end ( Fig. 1A ), some parapodia already removed. Body cylindrical, greyish; 49 mm long, 4 mm wide, cephalic cage 14 mm long, 36 chaetigers. Dorsal papillae with fine sediment particles, forming rounded tubercles, especially in anterior chaetigers ( Fig. 1B ); other papillae with less sediment or eroded, conical, elongate. Papillae arranged in 6–8 transverse, alternating rows.

Cephalic hood not exposed, branchial tips barely exposed (anterior end features observed in another specimen USNM 8952). Prostomium low cone, anterior eyes black, posterior ones not visible. Caruncle short. Lateral lips wide, projected, well developed; ventral and dorsal lips reduced.

Branchiae cirriform, thick, arrangement distorted by contraction ( Fig. 1C ), four filaments in a row and two lateral groups with two filaments. Palps lost; palp keels rounded. Nephridial lobes lost, scars between external distal branchiae and proximal ones.

Cephalic cage chaetae 3x as long as body width. Chaetigers 1–2 forming cephalic cage, chaetiger 3 with chaetae ½–? as long as second chaetiger ones. Chaetae arranged as short series, dorsolateral in chaetigers 1-3, and following chaetigers. Chaetiger 1 with 18 noto- and 12 neurochaetae, chaetiger 2 with 15 noto- and 8 neurochaetae, chaetiger 3 with 14 noto- and 6 neurochaetae. Anterior dorsal margin of first chaetiger with an anteriorly directed lobe, papillae eroded (up to five in smaller specimens, USNM 8945).

Anterior chaetigers with dorsal papillae forming large sediment tubercles. Chaetigers 1–3 increasing in size posteriorly. Chaetal transition from cephalic cage chaetae to body chaetae abrupt; anchylosed, falcate blunt neurohooks start in chaetiger 4 ( Fig. 1D ). Gonopodial lobes not seen (rounded, low, dark greyish lobes on chaetigers 5 and 6 in USNM 15384).

Parapodia poorly developed, reduced low chaetal lobes; chaetae emerge from the body wall. Parapodia lateral; medial neuropodia ventrolateral. Notopodia and neuropodia with two postchaetal papillae, neuropodial ones smaller.

Medial notochaetae arranged in a È-pattern; all notochaetae multiarticulated capillaries, articles short basally, medium-sized medially, long subdistally and distally ( Fig. 1E ), 10 per fascicle, as long as body width. Neurochaetae multiarticulated capillaries in chaetigers 1–3; simple anchylosed neurohooks from chaetiger 4, arranged in transverse series, 4–5 hooks per fascicle in anterior and medial chaetigers ( Fig. 1F ).

Posterior end missing in neotype. Other specimens with posterior end truncate, conical, with anus terminal, without anal cirri.

Variation. The complete specimens show wide variation in several features as follows (measurements in millimetres):

Remarks. Pherusa plumosa ( Müller, 1776) was briefly described and has been recorded from many different and distant localities all over the world. The species is herein restricted to include specimens provided with golden chaetae, following the redescription by Müller (1789:16), and with papillae covered mostly by fine sediment particles, forming a globular smooth surface, as stated in the above redescription. Støp-Bowitz (1948a) followed Fauvel (1927) for the definition of the species. However, Fauvel indicated a very wide variation in type of sediment cover on dorsal papillae, ranging from sand to mud, as well as pigmentation, juveniles varied between dark orange or rusty yellow, and adults from greenish, dark brown or even iron gray. This is a very wide definition and must be restricted. Likewise, the synonymy by Pettibone (1956:563) should be re-evaluated; the records by Okuda (1937:52), Ushakov (1955:309; 1965:285), and by Hobson & Banse (1981:58) need confirmation (see below).

As Pherusa plumosa is the type species of Pherusa , its original description was brief. The original material was either never deposited or was destroyed, and requests to collection managers in major European museums led to the conclusion that there is no type material available ( ICZN 1999, Art. 75.3.4) and therefore a neotype is designated to clarify the taxonomic status of the species ( ICZN 1999, Art. 75.3.1–75.3.3). Further, the original description was brief but as stated above its description contains useful information to discriminate the species from similar ones such as the relative cephalic cage chaetae pigmentation, which is consistent with the neotype ( ICZN 1999, Art. 75.3.5). The neotype was collected in northern Greenland, far away from the supposed type locality, but the oceanic conditions are comparable along the Western Greenland coast ( McGinley 2008). The neotype and other Greenlandic specimens are believed to be conspecific ( ICZN 1999, Art. 75.3.6), and have been deposited in the National Museum of Natural History, Smithsonian Institution ( ICZN 1999, Art. 75.3.7).

The number of notochaetae has been regarded as remarkably constant despite size variations ( Schlieper 1927:334); thus Baltic Sea specimens 1.3 cm long with 21 chaetigers, or those being 6.5 cm long with 45 chaetigers, have only 5 notochaetae in chaetiger 10. Therefore, there are apparently two forms involved under the same name, which has been regarded as very variable by Haase (1915:190); one is characterized by 5–6 notochaetae while the other has 7 or more notochaetae. The neotype and additional specimens all had seven or more notochaetae; those specimens having fewer notochaete may belong to another species. Further, the difference in the number of notochaetae in medial chaetigers is useful to separate similar species present along the Northwestern Atlantic Ocean ( Appy et al. 1980). Nevertheless, as indicated in the key above, because notochaetae are brittle, the relative type and sediment cover, together with number of neurochaetae, are more reliable as diagnostic features. Therefore, specimens which can be referred to as P. plumosa have fine particles on body papillae, while those with large sediment particles, often a single sand grain per papilla, and along anterior, medial and posterior regions, are herein regarded as members of P. incrustata Quatrefages, 1866 , reinstated (see below). Specimens previously regarded as members of P. plumosa but having few notochaetae per bundle belong in Pherusa obscura Quatrefages, 1849 , reinstated (see below). On the other hand, this revised definition of Pherusa plumosa ( Müller, 1776) , resembles P. nipponica n. sp. because their papillae are covered by fine sediment particles. The main differences between P. plumosa and P. nipponica refer to the relative number of transverse series of papillae, and the shape and colour of their neurohooks; thus, P. plumosa has 6–8 transverse series of papillae and neurohooks brownish, slightly falcate, whereas P. nipponica has 3–4 series and their neurohooks are paler and markedly curved.

Earlier Støp-Bowitz (1948a:20–24) had suggested that size was a useful character to split and describe two similar species: P. arctica and P. falcata , being 2–20 mm long. Both species were provided with apparently pseudocompound neurohooks along a few anterior chaetigers. Eliason (1962:62) showed that very small specimens of P. plumosa have these chaetae and he regarded P. arctica as a junior synonym. Type material was not available for this study but his conclusion is herein supported. Pherusa falcata , however, is newly combined and transferred to Lamispina n. gen. (see below).

Neotype locality. Conical Rock , Igannaq, Northwestern Greenland, 50–120 m depth.

Distribution. The species was described from Southwestern Greenland; it extends into temperate environments, especially in the Atlantic Ocean, in 22–600 m depth. Other records are questionable but this wide distribution probably includes more than one biological species and with the available characters they cannot be separated.

Figures

FIGURE 1. Pherusa plumosa (Müller, 1776). A. Neotype (USNM 23257), complete specimen, dorsal view. B. Anterior end, dorsal view. C. Another specimen (USNM 8952), head, frontal view (branchiae and palps removed; BS: branchial scar, LL: lateral lip, PS: palp scar, VL: ventral lip). D. Neotype, anterior end, right side, ventral view. E. Same, chaetiger 9, notochaetae. F. Same, neurochaetae. Scale bars: A: 7.3 mm, B: 1.2 mm, C: 1 mm, D: 0.67 mm, E: 0.33 mm, F: 0.3 mm.

FIGURE 2. Pherusa affinis (Leidy, 1855), paraneotypes (USNM 1251742). A. Anterior end, dorsal view. B. Same, ventral view. C. Non-type specimen (USNM 40214), anterior end, oblique dorsal view. D. Same, head, frontal view (branchiae and palps removed; BS: branchial scar, LL: lateral lip, PS: palp scar). E. Another paraneotype (USNM1251742), chaetiger 10, right notopodium (insets: basal and medial chaetal regions). F. Same, chaetiger 21, right neuropodium (insets: neurochaetal tips). Scale bars: A: 0.80 mm, B: 0.76 mm, C: 1.2 mm, D: 0.70 mm, E: 110 µm, F: 100 µm.

FIGURE 3. Pherusa andersonorum n. sp. A. Holotype (LACM 2602), oblique lateral view. B. Same, anterior end, ventral view showing ventral pharyngeal organ. C. Paratype (LACM 2603), anterior end, dorsal view, methyl green staining. D. Same, head, partly everted (branchiae and palps removed; BS: branchial scar, NL: nephridial lobe, PS: palp scar). E. Another paratype with one palp and all branchiae preserved (Pa: palp, VPO: ventral pharyngeal organ). F. Another paratype, cross section of a medial segment. G. Same, chaetiger 5, right neurochaetae. H. Same, chaetiger 20, right neurochaetae. Scale bars: A: 2.7 mm, B: 0.9 mm, C: 1.1 mm, D: 0.3 mm, E: 0.7 mm, F: 0.25 mm, G: 50 µm, H: 46 µm.

FIGURE 4. Pherusa aspera (Stimpson, 1854). A. Neotype (USNM 8889), anterior region, dorsal view. B. Same, ventral view. C. Another specimen (USNM 8957), head, frontal view (branchiae and palps removed; BS: branchial scar, LL: lateral lip, PS: palp scar). D. Neotype, chaetiger 10, right notopodium (inset: chaetal tips). E. Same, chaetiger 9, neurochaetae (two smaller neurochaetae not shown). Scale bars: A, C: 0.7 mm, B: 0.9 mm, D: 225 µm, E: 112 µm.

FIGURE 5. Pherusa hobsonae n. sp. A. Holotype (USNM 43803), lateral view. B. Anterior end, dorsal view. C. Same, right side, ventral view. D. Paratype (USNM 1131565), anterior end, dorsal view, tunic removed. E. Same, head, frontal view (branchiae and palps removed; BS: branchial scar, NL: nephridial lobe, PS: palp scar). F. Paratype, chaetiger 12, right parapodium, notochaetae (inset: basal and distal regions). G. Same, chaetiger 12, right parapodium, neurochaetae (one not shown). Scale bars: A: 3 mm, B: 2.2 mm, C: 1.7 mm, D: 1 mm, E: 0.5 mm, F: 0.25 mm, G: 45 µm.

FIGURE 6. Pherusa incrustata de Quatrefages, 1866, reinstated. A. Syntype (MNHN 382), dorsal view (inset: posterior region of dried syntype with large dorsal sediment particles). B. Anterior end, dorsal view (body wall damaged by removal of sediment particles). C. Anterior end, ventral view. D. Non-type specimen (MNHN 507), anterior end, dorsal view. E. Another non-type specimen (MNHN 183), head, frontal view (branchiae and palps removed; BS: branchial scar, LL: lateral lip, PS: palp scar; *: nephridial lobes base). F. Syntype (MNHN 381), chaetiger 10, basal, medial and distal notochaetal regions. G. Same, chaetiger 10, neurochaetae (2 broken). Scale bars: A: 3 mm, B: 2 mm, C: 1.9 mm, D: 1.4 mm, E: 0.8 mm, F: 0.3 mm, G: 0.4 mm.

FIGURE 7. Pherusa mikacae n. sp. A. Holotype (NHMR 17740), anterior end, dorsal view. B. Paratype (NHMR 17741), anterior end exposed, ventral view (palps corrugated, branchiae smooth). C. Paratype (ECOSUR), anterior end, dorsal view. D. Same, ventral view. E. Same, anterior region, ventral view. F. Parapodium 12, notochaetae (inset: basal, medial and distal regions). G. Same, parapodium 12, neurochaetae with eroded tips (inset: paratype NHMR 17742, parapodium 10, tip of neurohook). Scale bars: A: 0.9 mm, B: 0.8 mm, C, E: 0.7 mm, D: 1.3 mm, F: 160 µm, G: 80 µm.

FIGURE 8. Pherusa moorei n. sp., holotype (USNM 5391). A. Dorsal view. B. Anterior end, dorsal view. C. Anterior end, ventral view. D. Chaetiger 12, notochaetae (insets: basal, medial and distal regions). E. Chaetiger 9, neurochaetae (inset: tips of two chaetae). F. Chaetiger 33, neurochaetae (insets: tips of chaetae). Scale bars: A: 2.2 mm, B: 1.7 mm, C: 1.5 mm, D: 0.4 mm, E: 260 µm, F: 200 µm.

FIGURE 9. Pherusa neopapillata Hartman, 1961. A. Holotype (LACM 531), lateral view. B. Paratype (LACM 532), anterior end, dorsal view, some sand particles removed. C. Same, chaetiger 11, notochaetae. D. Same, chaetiger 6, right parapodium, neurochaetae. E. Same, chaetiger 27, right parapodium, neurochaetae. Scale bars: A: 0.8 mm, B: 0.9 mm, C: 0.4 mm, D: 0.2 mm, E: 0.1 mm.

FIGURE 10. Pherusa nipponica n. sp. A. Holotype (CMNH 305), before being brushed-off, anterior end, dorsal view. B. Same, after removal of foreign materials, anterior end, slightly oblique dorsal view. C. Same, posterior end, oblique dorsal view. D. Paratype (CMNH 1534), head, frontal view (branchiae and palps removed; BS: branchial scar, LL: lateral lip, NL: nephridial lobe, PS: palp scar). E. Same, chaetiger 10, right parapodium, anterior view, some chaetae broken (insets: basal and distal notochaetal regions; neurochaetae). F. Same, chaetiger 35, left parapodium, neurochaetae. Scale bars: A: 1.1 mm, B: 0.9 mm, C: 1.0 mm, D: 190 µm, E: 260 µm, F: 80 µm.

FIGURE 11. Pherusa obscura Quatrefages, 1849, reinstated. A. Holotype (MNHN 627), dried-out, anterior region in dorsal view. B. Same, anterior end, dorsal view. C. Non-type specimen (LACM 10552), anterior end in lateral view, head everted. D. Same, head, frontal view (BS: branchial scar, LL: lateral lip, NL: nephridial lobe, VPO: ventral pharyngeal organ). E. Non-type specimen (MNHN A183), chaetiger 12, right parapodium, notochaetae (insets: basal, medial and distal regions). F. Same, chaetiger 12, neurochaetae. G. Same, chaetiger 53, right parapodium, anterior view. Scale bars: A: 1.7 mm, B: 1.2 mm, C: 2 mm, D: 0.7 mm, E: 450 µm, F: 130 µm, G: 0.5 mm.

FIGURE 12. Pherusa papillata (Johnson, 1901). A. Syntypes (MCZ 1900), dorsal view. B. Same, anterior fragment, anterior end, dorsal view. C. Same, anterior end, ventral view (branchiae and palps exposed). D. Non-type specimen (USNM 43821), head, frontal view (branchiae and palps removed; BS: branchial scar, NL: nephridial lobe, PS: palp scar). E. Same, chaetiger 9, right parapodium, neurochaetae. F. Same, chaetiger 25, right parapodium, posterior view (insets: basal and distal notochaetal regions, largest neurohook). Scale bars: A: 3.3 mm, B: 1.5 mm, C: 0.9 mm, D: 0.4 mm, E: 0.1 mm, F: 0.3 mm.