Pherusa andersonorum, Salazar-Vallejo, 2014

Salazar-Vallejo, Sergio I., 2014, Revision of Pherusa Oken, 1807 (Polychaeta: Flabelligeridae), Zootaxa 3886 (1), pp. 1-61 : 15-17

Pherusa andersonorum n. sp.

Figure 3

Type material. Northeastern Pacific Ocean. California. Holotype ( LACM 2602 ) and 4 paratypes ( LACM 2603 ), off Goleta sewer outfall pipe (34°24.6' N, 119°44.5' W), Santa Barbara, in Macrocystis holdfast, plant dead 3–4 months before being collected, 12 m, 18 Feb. 2004, S. Anderson, coll.

Additional materials. Northeastern Pacific Ocean. California. One specimen ( LACM 6529 ), anterior fragment, Salmon Point , Mendocino County, rocky shore, tide pools, 10 Jun. 1949, W.K. Emerson, coll. (5.3 mm long, 1.5 mm wide, cephalic cage 3 mm long, 22 chaetigers). One specimen ( USNM 49791 ), complete, dorsally dissected previously, Los Angeles Harbor, Los Angeles, California (no further data), V.L. Human, coll. (18 mm long, 3 mm wide (distorted by compression), cephalic cage 5 mm long, 41 chaetigers; gonopodial lobes not seen; 7 notochaetae in chaetiger 10). Washington. Two specimens ( USNM 1260292 ), one complete and an anterior fragment, off Cantilever Pier, Friday Harbor Bay , San Juan Archipelago , 37 m, 15 Sep. 1962, M.E. Rice, coll. (complete specimen 55 mm long, 4 mm wide, cephalic cage 12.5 mm long, 68 chaetigers; 9 notochaetae in chaetiger 10) .

Description. Holotype (LACM 2602; Fig. 3A, B ) complete; body cylindrical, slightly tapered posteriorly; 21 mm long, 2.8 mm wide, cephalic cage 6 mm long, 43 chaetigers. Papillae with sand particles, especially along dorsal anterior papillae ( Fig. 3C ); anterior notochaetae with epizoic ciliates ( Fig. 3F ). Papillae arranged in 3–4 alternating transverse series.

Cephalic hood not exposed. Prostomium (observed in paratypes) low cone; four red eyes, anterior ones larger ( Fig. 3D, E ). Caruncle short. Palps large, 1.5–2.0 x longer and wider than branchiae; palp keels rounded, low. Lateral lips well developed; ventral and dorsal lips reduced.

Branchiae cirriform ( Fig. 3E ); four filaments arranged in a single row, two lateral pairs with two filaments each; filaments smaller and thinner than palps. Nephridial lobes short, placed below inner (third counting from the dorsalmost) branchiae.

Cephalic cage chaetae about ¼ as long as body, twice as long as body width. Chaetigers 1–3 forming cephalic cage; chaetae arranged in short series, dorsolateral in chaetiger 1, become lateral in chaetigers 2–3. About 10 noto- and 8 neurochaetae in chaetiger 1, 8 and 6 in chaetiger 2, and 6 and 5 in chaetiger 3.

Anterior dorsal margin of first chaetiger with a trilobed, low projection (better developed in paratypes, Fig. 3C ). Chaetigers 1–3 of about the same length. 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 ( Fig. 3F ). Notopodial lobes low, with one pre- and two long postchaetal papillae. Neuropodia lobes lower with one anterior, two posterior, and an inferior long 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; about 8 per fascicle, as long as body width, longer in posterior chaetigers. Neurochaetae multiarticulated capillaries in chaetigers 1–3; falcate anchylosed neurohooks from chaetiger 4, arranged in transverse series ( Fig. 3G ), 3 neurohooks anteriorly, becoming smaller, thicker, darker ( Fig. 3H ), up to 4 posteriorly.

Posterior end with long chaetae, notochaetae twice as long as body width; pygidium conical, truncate, anus depressed, terminal; without cirri.

Variation. The smallest paratype (7.5 mm long, 1 mm wide, cephalic cage 2.5 mm long, 31 chaetigers) has hooks with tips pale, depressed, thin, in chaetiger 4 and present through 10 chaetigers; they are replaced from the dorsalmost by dark anchylosed neurohooks, with the inferior hook the last to be replaced. This specimen had only 6 notochaetae per bundle in medial chaetigers. Other paratypes, being twice as large (10 mm long, 2 mm wide, cephalic cage 4 mm long, 40 chaetigers), have some similar neurohooks in fewer anterior neuropodia; the largest paratype (22 mm long, 3 mm wide, cephalic cage 5 mm long, 48 chaetigers) however, lacks them completely. Many paratypes have their anterior end everted because they were narcotized with MgCl 2; several were mature.

Remarks. Pherusa andersonorum n. sp. belongs to the group of species whose dorsal body papillae have sand particles on them. This group also includes P. aspera ( Stimpson, 1854) , P. incrustata Quatrefages, 1866 reinst., P. neopapillata Hartman, 1961 , and P. obscura Quatrefages, 1849 reinst. However, the only two species with sand particles present throughout the body are P. andersonorum n. sp. and P. aspera and despite their resemblance to each other, they differ in the relative number of neurohooks in medial and posterior chaetigers. In P. andersonorum n. sp., there are 3–4 neurohooks (body 2.8 mm wide), whereas P. aspera has more neurohooks per bundle (5–6; body 2 mm wide). These two species are found in different habitats: P. andersonorum n. sp., lives in dead kelp holdfasts in subtidal rocky bottoms, whereas P. aspera thrives in shelly bottoms in depths to 45 m ( Appy et al. 1980:33).

Etymology. This species is named after Genevieve and Shane Anderson, enthusiastic marine biologists formerly working at Santa Barbara City College and University of California, Santa Barbara, respectively. It is a modest homage to their achievements in teaching and research, and to thank them for their support by collecting and providing the means to study their materials. The epithet is a plural noun in the genitive case.

Type locality. Off Santa Barbara , California, USA, in dead Macrocystis holdfasts, in shallow depths (12 m) .

Distribution. Washington to Southern California, in mixed or rocky bottoms in shallow depths (0–37 m).

Figures

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.