Pherusa incrustata de Quatrefages 1866

Pherusa incrustata Quatrefages, 1866, reinstated

Figure 6

Pherusa incrustata Quatrefages, 1866:480.

Stylarioides plumosa.— Fauvel 1907:20, 1909:6, 1927:116–117, Figs 41a–g.— 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).

Type material. Mediterranean Sea. Syntypes (MNHN 380–382), collected by J.-C. Savigny, no further data (syntype 382 used for redescription; syntype 380 dried out but retaining sand grains cover; 50 mm long, 2.5 mm wide, cephalic cage 10 mm long, 63 chaetigers; syntype 381 is an anterior fragment, 70 mm long, 5.5 mm wide, cephalic cage 20 mm long, 39 chaetigers, sand grains removed).

Additional material. Northeastern Atlantic Ocean, Norway. One anterior fragment (LACM 6530), Hardangerfjorden, Norway, Sta. 8-60, 18– 42 m, 22 Oct. 1958, K. Fauchald, coll. (34 mm long, 4.5 mm wide, cephalic cage 10 mm long, 36 chaetigers; dorsal papillae on anterior chaetigers large, with sand grains; 4–5 rows per segment; neurohooks from chaetiger 4, 4, then 3 per fascicle; notochaetae as long as ½ body width). Eight specimens (MNHN 183), only one complete, Bergsfjord (69°27'00" N, 17°18'00" E), 1881–1894, M. Pouchet, coll. (one anterior fragment dissected; complete 15 mm long, 3 mm wide, cephalic cage 7 mm long, 33 chaetigers; 7 notochaetae in chaetiger 10). Denmark. Four specimens, two complete (MCZ 1346), no further data (32–42 mm long, 3.5–4.0 mm wide, cephalic cage 7–8 mm long, 53–54 chaetigers; dorsal papillae on anterior chaetigers large, rounded, with fine sediment and sand grains, 4–5 rows per segment; 6–7 notochaetae in chaetiger 10, notochaetae as long as ½ body width; neurohooks from chaetiger 4, 4 (3) in anterior chaetigers, 3 in posterior ones per fascicle). One specimen without posterior end (ZMUH 15394), North Sea, no further data (81 mm long, 6 mm wide, cephalic cage 12 mm long, 60 chaetigers; anterior papillae with sand particles; 7 notochaetae in chaetiger 10). Twenty-three anterior fragments (ZMUH 19245), partly dried-out, Kieler Bucht (no further data), Kühlmorgen-Hille, coll. (1–4 mm wide, cephalic cage 3–17 mm long; 5–8 notochaetae in chaetiger 10; smallest complete specimen 4 mm long, 1 mm wide, cephalic cage 3 mm long, 41 chaetigers; all with sand grains over anterior chaetigers and neurohooks from chaetiger 4). Faroe Islands. Anterior fragment (MNHN 183), 1899, RV La Manche Expedition to the Faeroes (Føroyar) Archipelago (62°05' N, 00°45' W), no further data (37 mm long, 3.5 mm wide, cephalic cage 8 mm long, 47 chaetigers; 8 notochaetae in chaetiger 10). France. One specimen (MNHN 183), complete, partly dried-out, Wimereux, Nord-Pas-de-Calais (50°46'00" N, 01°37'00" E), no further data (59 mm long, 6 mm wide, cephalic cage 11 mm long, 70 chaetigers; 8 notochaetae in chaetiger 10). Two specimens (MNHN 183), one complete, partly dried-out, Tatihou, off Saint Vaast-la-Houge, no further data (complete 52 mm long, 4.8 mm wide, cephalic cage 11 mm long, 65 chaetigers; 7 notochaetae in chaetiger 10). Three specimens (MNHN 183), dried-out, Saint- Vaast-la-Hogue (49.35° N, 01.16° W), 20 Aug. 1894, B. de Saint-Joseph, coll. (sand particles on some body papillae). Two specimens (MNHN 457) complete, anterior end partially everted, St. Vaast, Aug. 1908, fixed in Bouin, P. Fauvel, coll. (37–49 mm long, 4.0– 4.5 mm wide, cephalic cage 9.0– 9.5 mm long, 65 chaetigers; chaetigers 1–3 with sand grains forming a single mass). Seven specimens (MNHN 457), some with anterior end exposed, Tatihou, 1895, P. Fauvel, coll. (10–47 mm long, 1.5–5.0 mm wide, cephalic cage 3–9 mm long, 31–62 chaetigers; chaetae in chaetiger 10: 6–7 noto- and 3–4 neurochaetae; slightly size-dependent). Two specimens (MNHN 507), Tatihou, May 1895, P. Fauvel, coll. (13.2–36.0 mm long, 3.0– 3.5 mm wide, cephalic cage 8.5–9.0 mm long, 37 (reg. post. end)–59 chaetigers; chaetae in chaetiger 10: 6–7 noto- and 3 neurochaetae).

Description. Syntype (MNHN 382) complete, most sand grains removed (Fig. 6A), when present giving a granulose appearance (Fig. 6D), even some posterior notochaetal bundles trimmed off. Body pale, cylindrical, tapered posteriorly, distorted by compression over anterior and posterior ends; 57 mm long, 5.5 mm wide, cephalic cage 10 mm long, 72 chaetigers. Body papillae arranged in 7–9 transverse rows per chaetiger dorsally (Fig. 6B), and ventrally (Fig. 6C).

Anterior end not exposed (anterior features based on a non-type specimen, MNHN 183). Cephalic hood short, margin smooth. Prostomium pale, low; four eyes, dark brown, anterior ones larger. Caruncle short, triangular. Palps thick, contracted, palp lobes low, rounded. Lips distorted by contraction; dorsal and lateral lips fused, ventral lip not seen.

Branchiae cirriform, arranged as two concentric rows; four filaments in a continuous row, and two lateral groups, each with two filaments, all of about the same size and width, about half as long as palps. Nephridial lobes placed on the inner side of the anterior branchial groups (Fig. 6E, asterisk).

Cephalic cage chaetae about 1/6 as long as body length, about twice as long as body width. Chaetigers 1–3 forming cephalic cage; chaetae arranged in short series, 12–14 notochaetae for first two chaetigers, about 10 in chaetiger 3 and 6–8 neurochaetae per bundle. Chaetigers 1–3 of about the same size. Anterior margin of chaetiger 1 papillate; with larger sand tubercles (Fig. 6B, D), papillae similar throughout following chaetigers. Chaetal transition from cephalic cage to body chaetae abrupt; anchylosed, falcate, blunt neurohooks from chaetiger 4. Gonopodial lobes not seen.

Parapodia poorly developed, chaetae emerge from body wall. Parapodia lateral; medial neuropodia ventrolateral. Notopodial lobes with 2–3 pre- and 2–3 postchaetal papillae, slightly larger than adjacent ones. Neuropodial lobes more heavily eroded, with about 1–2 postchaetal papillae.

Medial notochaetae arranged in a È-pattern, transverse to body axis, directed dorsally; all notochaetae multiarticulated capillaries, articles short basally, medium-sized medially, long distally (Fig. 6F); 9–10 notochaetae per bundle, as long as half body width. Neurochaetae multiarticulated capillaries in chaetigers 1–3; falcate, anchylosed neurohooks from chaetiger 4, arranged in oblique series, 4–5 per ramus along anterior chaetigers, 4 in posterior chaetigers.

Posterior end rounded, with long chaetae, most broken; pygidium conical, truncate, anus dorsoterminal, without dorsal cirri.

Variation. Despite the large size variation, the number of notochaetae per chaetiger (chaetiger 10) was quite consistent; other features varied as follows.

The number of neurochaetae is size dependent; the largest syntype (MNHN 381) has 6–7 neurospines per bundle in anterior chaetigers (Fig. 6G), and 4–5 in posterior chaetigers.

Remarks. Pherusa incrustata Quatrefages, 1866, reinstated, groups with other species having sand particles on their dorsal body papillae, including P. andersonorum n. sp., P. aspera (Stimpson, 1854), P. neopapillata Hartman, 1961, and P. obscura Quatrefages, 1849 reinst. Two species, P. andersonorum n.sp. and P. aspera, differ from the others as body papillae are encrusted. By having 7–10 transverse rows of papillae per segment, P. incrustata resembles P. neopapillata, differs in the relative abundance of cephalic cage chaetae and on the extension of sand particles along the body. In P. incrustata there are many more cephalic cage chaetae (10–14 notochaetae, 6–8 neurochaetae per bundle), and sand particles are present in anterior to medial segments, whereas in P. neopapillata there are less cephalic cage chaetae (6–8 chaetae per fascicle), and sand particles are restricted to anterior segments.

Distribution. The original label indicates syntypes were collected by J.-C. Savigny in the Mediterranean Sea. It is unknown if this refers to the coasts of Egypt, or France, but the then common terminology separated the Atlantic from the Mediterranean shores, and included country names for other locations, such that it could have been found on the French Mediterranean coasts. The materials available indicate it is present in the Mediterranean and Eastern Atlantic areas, in shallow water (18–42 m depth).