Eusyllis grandmariae, Brusa, Vivian S., Aguado, M. Teresa, Martín, Guillermo San & Rouse, Greg, 2013

Brusa, Vivian S., Aguado, M. Teresa, Martín, Guillermo San & Rouse, Greg, 2013, Revision of the genus Eusyllis Malmgren, 1867 (Annelida: Phyllodocida: Syllidae: Eusyllinae), with the description of a new species from the eastern Pacific Ocean, Zootaxa 3599 (1), pp. 37-50 : 42-43

Eusyllis grandmariae n. sp.

( Figs. 1 , 2 A–E, 3 A–E & 4 A–D)

Material examined. Holotype (SIO-BIC A3234) and 4 paratypes (SIO-BIC A3235), collected via ROV Doc Ricketts on October 2nd 2009, on a juvenile whale carcass ( Eschrichtius robustus ) initially sunk the 5th October 2004 at 633m depth (38.802 ºN 122.994ºW—Monterey Submarine Canyon, California, U.S.A. North Pacific Ocean); collected by Greg Rouse.

Description. Body fragile, all specimens fragmented, holotype complete specimen, in nine fragments, with 12 + 4 + 4 + 4 +2 +4 + 6 + 3 + 6 segments, 6.5 mm total length for about 45 chaetigers. Anterior end distinctly convex dorsally. Prostomium ovate, wider than long, with four reddish eyes in trapezoidal arrangement, anterior pair bigger than posterior one. Lateral antennae longer than prostomium and palps together, on anterior margin of prostomium; median antenna about two times longer than lateral ones, between anterior eyes, usually posteriorly directed ( Fig. 2 A). Palps large and relatively short, triangular, slightly fused at basis ( Figs. 2 A, 3A, 3B). Nuchal organs distinct, semi-circular, pigmented in brown ( Fig. 2 A), extending laterally over prostomium. Tentacular segment narrow, shorter than subsequent segments ( Fig. 2 A). Dorsal tentacular cirri longer than lateral antennae, shorter than median one; ventral tentacular cirri less than half long as dorsal ones ( Fig. 2 A). Antennae, tentacular cirri and dorsal cirri smooth, filiform. Dorsal cirri alternating in length (as long as median antenna or shorter respectively), wider at basis and getting narrower at tips; cirrophores well developed ( Figs. 2 A, 2C). Parapodia ovate, with two distal lobes ( Fig. 3 E, arrow). Ventral cirri distinctly triangular ( Figs. 2 C, 3E, arrow). A dark internal gland, spherical or kidney-shaped at basis of each parapodium ( Fig. 2 C). Compound heterogomph chaetae, with long shafts ( Figs. 2 A, 2C, 3A, 3D); numerous (9–11) chaetae per parapodium ( Figs. 2 A, 2C, 3A, 3D). Blades slender, longer on anterior parapodia; minutely bidentated, distal tooth somewhat hooked, proximal tooth small, spine-like; short spines on margin, more developed basally, shorter towards tips ( Figs. 2 D, 2E, 4A–D). Distinct dorso-ventral gradation of blades length, 42–49 µm dorsally, 31–40 µm ventrally (anterior parapodia), 32–42 µm dorsally, 23–35 ventrally (posterior parapodia). Two aciculae per parapodium, distally expanded, tapered ( Figs. 2 D, 2E). Pharynx wide, through five segments, with a crown of 10 big soft papillae and a crown of numerous smaller basal papillae; incomplete ( Fig. 3 C, 3D) or complete ( Fig. 2 B) denticled arc, with about 53 short, acute teeth, and a conical anterior dorsal pharyngeal tooth ( Figs. 2 B, 3C, 3D); proventricle as long as pharynx, through six segments, with about 30 muscle cell rows. Short pygidium and long anal cirri.

Distribution. Monterey Bay, California, U.S.A., North West Pacific Ocean

Habitat. This is the only species of the genus recorded from whale bones.

Remarks. Eusyllis grandmariae n. sp. is unique in having compound chaetae with elongated blades, short spines on margin and minute, spine-like proximal teeth. Only E. longicirrata Imajima, 1966 , from Japan, has similar chaetae. However, it has chaetae about twice longer, much longer dorsal cirri, two to five times longer than body width, digitiform ventral cirri (triangular in the new species), and palps totally separated.

Etymology. In loving memory of Maria Brusa, the first author’s grandmother.

Figures

FIGURE 1. Eusyllis grandmariae n. sp. (Holotype alive, dorsal view).

FIGURE 2. Eusyllis grandmariae n. sp. (Holotype) (A) anterior part, dorsal view; (B) pharynx and denticled arc; (C) crosssection of a body segment; (D – E) compound chaetae and aciculae. Scales: A 10 µm, B 20 µm, C 10 µm, (D – E) 40 µm.

FIGURE 3. Eusyllis grandmariae n. sp. (Paratype) SEM. (A) anterior part, dorsal view; (B) prostomium and anterior segments; (C) everted pharynx; (D) anterior part, ventral view; (E) parapodia, ventral view.