Pherusa obscura Quatrefages, 1849

Salazar-Vallejo, Sergio I., 2014, Revision of Pherusa Oken, 1807 (Polychaeta: Flabelligeridae), Zootaxa 3886 (1), pp. 1-61 : 31-33

Pherusa obscura Quatrefages, 1849 , reinstated

Figure 11

Pherusa obscura Quatrefages, 1849:289–290 , Pl. 9, Figs 15–17 .

Trophonia borealis Hansen, 1880:230 , Pl. 4, Figs 8–12 ; 1882:38, Pl. 7, Figs 13–16 .

Stylarioides plumosus .— Haase 1915: 187–192 (partim, non Müller, 1776).

Stylarioides plumosa . — Fauvel 1927:116–117, Fig. 41a–g (partim, non Müller, 1776).

Type material. Northeastern Atlantic Ocean, English Channel. Holotype ( MNHN 627 ), Saint-Vaast-la-Hogue, Basse Normandie, France, 1868 (date probably wrong since the species was described in 1849).

Additional material. Norway. One specimen ( SMF 15336), Kroken, 27 Feb. 2005, Udekem & Acoz, coll. (preserved in alcohol; 62 mm long, 5 mm wide, cephalic cage 10 mm long, 66 chaetigers; dorsal papillae in chaetigers 1–3 forming larger sediment particles, 6 rows per segment; neurohooks from chaetiger 4, 3–5 anteriorly, 3–4 posteriorly per fascicle; notochaetae about as long as ½ body width, 5–6 per bundle; parapodia with 2–3 papillae slightly longer than other papillae of the same segment; oocytes black, perhaps by preservative, about 100?m) . Denmark. Four specimens, 3 complete ( LACM 6531 ), Øresund , RV Thelma, Modiolus community, 1 Jul. 1960 (12.5–51.0 mm long, 3–7 mm wide, cephalic cage 7–12 mm long, 33–65 chaetigers; dorsal papillae in anterior chaetigers long, with sand particles, 4–5 or 5–6 rows per segment; neurohooks from chaetiger 4, 3–5 anteriorly, 3–4 posteriorly per fascicle; notochaetae as long as ½ body width, 4–5 per bundle; parapodia with papillae slightly longer than other papillae of the same segment). One specimen ( MNHN A183 ), broken into two pieces, partially dehydrated, Steensund , Hyllekrog , Lolland, Denmark, 26 Aug. 1908, C. Gravier, coll. (28+ 18 mm long, 4 mm wide, cephalic cage 10 mm long, 66 chaetigers; 5 notochaetae per bundle in chaetiger 13). One specimen ( MNHN A183 ), Steensund, Hyllekrog (54.36° N, 11.30° E), 26 Aug. 1908, C. Gravier, coll. (48 mm long, 5 mm wide, cephalic cage 10 mm long, 66 chaetigers; dorsal papillae on anterior chaetigers long, sediment mostly eroded, 4–5 rows per segment; neurohooks from chaetiger 4, 3–4 anteriorly, 3 posteriorly per fascicle; notochaetae as long as 1/3 body width, 5–6 per bundle) .

Description. Holotype (MNHN 627) complete, dried-out, pale, distorted ( Fig. 10A, B ), 30 mm long, 2 mm wide, cephalic cage 7 mm long, 47 chaetigers. Body papillae digitate (collapsed in holotype), with some sand particles on a few anterior chaetigers; 5–6 transverse rows of papillae on medial or posterior segments.

Cephalic hood exposed in a non-type specimen (LACM 6531), smooth, margin papillated ( Fig. 11C ). Prostomium projected cone; eyes brownish, anterior eyes twice as large as posterior ones ( Fig. 11D ). Caruncle short, triangular. Palps and branchiae lost. Lips distorted by eversion of ventral pharyngeal organ.

Branchial scars arranged as two concentric rows; one continuous row with 4 filaments with interbranchial, round, glandular lobes; four other filaments into two lateral groups, each with two filaments per side; size relationship to palps unknown. Nephridial lobes pale, short, digitate, emerging under division of branchial rows.

Cephalic cage chaetae ¼ as long as body, or 3.5x longer than body width. Chaetigers 1–3 forming cephalic cage; chaetae progressively smaller, arranged in short lateral series, about 8 per ramus.

Anterior dorsal margin of first chaetiger without a distinct medial lobe (probably eroded). Anterior chaetigers with longer papillae laterally, not associated with chaetal lobes. Chaetigers 1–3 progressively longer. Chaetal transition from cephalic cage to body chaetae abrupt; anchylosed, falcate, blunt neurohooks start in chaetiger 4. Gonopodial lobes not seen.

Parapodia poorly developed, slightly larger in a few anterior chaetigers, in subsequent chaetigers chaetae emerge from body wall. Parapodia lateral; medial neuropodia ventrolateral. Notopodia and neuropodia with short papillae, close to each other.

Medial notochaetae in transverse to oblique series; all multiarticulated capillaries, articles short in a reduced basal region, then medium-sized medially becoming slightly longer distally ( Fig. 11E , insets), about 8–9 per bundle, as long as 1/3 body width. Neurochaetae multiarticulated capillaries in chaetigers 1–3; brownish, blunt neurohooks from chaetiger 4, mostly 4 per bundle in anterior and medial chaetigers ( Fig. 11F ), 3 in posterior chaetigers ( Fig. 11G ).

Posterior end damaged, truncate conical, anus terminal, without anal cirri. One specimen (SMF 15336) with dark brown oocytes, about 100 µm in diameter.

Variation. The specimens show variations in some morphological features as follows. The number of notochaetae was 5–6 per bundle (chaetiger 10) but some chaetae may be broken and the holotype has 8–9 notochaetae per bundle.

Remarks. Pherusa obscura Quatrefages, 1849 , reinstated, groups with other species with dorsal papillae with sand particles such as P. andersonorum n. sp., P. aspera ( Stimpson, 1854) , P. incrustata Quatrefages, 1866 , reinstated, and P. neopapillata Hartman, 1961 . Sediment particles are present along the body in P. andersonorum and P. aspera , whereas the other species have them restricted to anterior or to anterior to medial segments. However, in P. obscura the cephalic cage is 3x as long as body width, and has 5–6 transverse series of papillae per segment, whereas in P. incrustata and P. neopapillata cephalic cages are smaller (twice as long as body width), and they have more transverse rows of papillae (7–10).

The lumping of the typical P. plumosa with P. obscura stems from the revision by Haase (1915). He studied many specimens including some from Arctic and Baltic Sea localities, whose number of notochaetae was very variable. Likewise, he overlooked the indication by Hansen (1880) that Trophonia borealis , a junior synonym of P. obscura , had sand and mud particles over the dorsal papillae. This was followed by Fauvel (1927:116) and by Støp- Bowitz (1948a:13). However, they were lumping together several different populations, some of which may have been of different species. Since he failed to provide any details about the papillae and the sediment on them, it is difficult to define this issue. The species can be defined by having large, sand particles along few anterior chaetigers and fine particles along the rest of the body. Pherusa incrustata , however, has been redefined above as having large, sand particles along the dorsum of the whole body.

The original description of Pherusa obscura by Quatrefages (1866:479) was based on a very large specimen (80 mm long, 9 mm wide, about 50 chaetigers). For the chaetal features, he stated (p. 480): “Les pieds sont biramés et à rames écartées et peu saillantes. La supérieure porte quatre à cinq soies simples et ordinaires. A la rame inférieure, on trouve trois soies simples aussi, mais renflées et recourbées en crochet à leur extrémité. This translates as: ‘The feet are biramous with distinct little prominent rami. The dorsal carries four to five simple ordinary chaetae. In the ventral, we find three simple chaetae too, but distally swollen and falcate.” Therefore, because the specimen indicated as the holotype differs in size and collecting date, this reinstatement is made with some hesitation because this specimen is not the original one. Better topotype specimens would help clarify if this is the corresponding species although the type material might be lost.

Distribution. Scandinavia to the Mediterranean Sea, in subtidal depths and in mussel beds. This is a wide distribution but with current characters they cannot be separated.

Figures

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.

FIGURE 13. Pherusa rullieri n. sp., holotype (MNHN 1556). A. Anterior end, dorsal view. B. Anterior end, ventral view. C. Same, close up. D. Chaetiger 11, right parapodium, anterior view (insets: basal and medial notochaetal regions, aristate neurohooks). E. Chaetiger 25, right parapodium, anterior view. F. Chaetiger from posterior fragment, right parapodium, anterior view. Scale bars: A: 1.6 mm, B: 1.2 mm, C: 1.0 mm, D: 0.25 mm, E: 0.1 mm, F: 0.2 mm.

FIGURE 14. Pherusa sibogae (Caullery, 1944) n. comb., holotype (ZMA 1599). A. Anterior end, dorsal view. B. Anterior end, ventral view. C. Posterior region. D. Chaetiger 11, right parapodium, notochaetae (insets: basal and medial regions). E. Chaetiger 11, right parapodium, neurohooks (inset: basal and distal regions). F. Chaetiger 20, right parapodium, neurochaetaae. Scale bars: A, C: 0.5 mm, B: 0.4 mm, D, E: 170 µm, F: 25 µm.

FIGURE 15. Laminspina schmidtii (Annenkova-Chlopina, 1924) n. comb. A. Best syntype (ZIRAS 27296), dorsal view. B. Same, anterior end, ventral view. C. Non-type specimen (ZIRAS 27298), head, partly eroded, frontal view (BS: branchial scar, LL: lateral lip, PS: palp scar, VPO: ventral pharyngeal organ). D. Stylarioides negligens, holotype (USNM 32683), anterior fragment, dorsal view. E. Same, posterior fragment, cross section of one segment. F. Same, notochaetal basal medial, subdistal and tip regions. G. Same, lamispine basal, medial and distal regions (inset: SEM tip). H) Same, two lamispines, medial, transformation regions. Scale bars: A: 1.6 mm, B: 1.3 mm, C: 0.3 mm, D: 0.8 mm, E: 0.5 mm, F, G: 40 µm, H: 60 µm.

FIGURE 16. Lamispina amoureuxi n. sp. A. Holotype (MNHN 1557), anterior fragment, ventral view. B. Same, anterior end, dorsal view. C. Paratype (MNHN 1558), head, frontal view, depressed by cover slip (branchiae and palps removed; BS: branchial scar, NL: nephridial lobe, PS: palp scar). D. Same, sediment particles removed, anterior region, ventral view (arrows point at gonopodial lobes). E. Same, chaetiger 9, notochaetae (insets: basal, transition, subdistal and tip). F. Same, chaetiger 9, lamispines (insets: basal, medial and distal regions plus tips of smaller lamispines). G. Holotype, posterior region, dorsal view. Scale bars: A: 1.6 mm, B: 0.6 mm, C: 0.2 mm, D: 0.8 mm, E: 0.3 mm, F: 0.4 mm, G: 0.5 mm.

FIGURE 17. Lamispina carrerai n. sp., holotype (USNM 17387). A. Complete specimen, dorsal view (anterior fragment at left). B. Anterior end, dorsal view. C. Anterior fragment, terminal segments, dorsal view. D. Chaetiger 11, right parapodium, notochaetae (inset: tips). E. Chaetiger 11, right parapodium, lamispines (inset: medial and distal regions). F. Posterior fragment, posterior end, dorsal view. Scale bars: A: 2.5 mm, B: 0.5 mm, C: 0.6 mm, D, E: 160 µm, F: 0.3 mm.