Pterocirrus bouchardi, Salazar-Vallejo, 2022

Salazar-Vallejo, Sergio I., 2022, New species of hesionid and phyllodocid polychaetes (Annelida, Errantia) from Clipperton Island, Zoosystema 44 (1), pp. 1-26 : 19-22

Pterocirrus bouchardi n. sp.

( Figs 5 ; 6 )

urn:lsid:zoobank.org:act:D44CEE99-D71E-494B-91B8-42386A8A08BE

TYPE MATERIAL. — Holotype. Clipperton Island • 1 specimen; Sta. 34; 10°18.75’N, 109°12.02’W; fallen coral mound; 20 m to 55 m; 26.I. 2005; S. Hourdez, K.-L. Kaiser, J.-M. Bompar, leg.; MNHN-IA-TYPE2046.

Paratypes. Clipperton Island • 3 specimens; Sta. 15 (no coordinates); chaetopterid tube mass and small stones; 37 m; 19.I.2005; J.-M. Bouchard, L. Albenga, L. Dugrais, leg.; MNHN-IA-TYPE2047 (anterior body third widest, without tentacular cirri, most dorsal cirri lost; largest paratype mature female, without posterior end; 6-5-17.0 mm long, 0.9-1.9 mm wide, complete paratypes with 76-98 segments, largest with 106 segments. 15-22 neurochaetae per bundle. Oocytes in parapodial space from segment 40, each 30-40 µm in diameter. Medium-sized specimen with blackish pigmentation along posterior body half) • 1 specimen; Sta. 24; 10°17.93’N, 109°14.00’W; coral rubble; night dive; 23 m; 22.I.2005; J.-M. Bouchard, L. Albenga, L. Dugrais, leg.; ECOSUR 278 (Body twisted, brownish anteriorly, dorsally with continuous pigmentation, darker inter-segmentally, ventrally up to segment 25 with a paler midventral oval area, following segments paler. Anterior fragment 6.6 mm long, 0.8 mm wide (excluding chaetae), 54 segments; dorsal tentacular cirri of segment 2 reach chaetiger 25-26; ventral tentacular cirri of segment 2 with long arista, tip curved; about 14 neurochaetae per bundle) .

ADDITIONAL MATERIAL. — Clipperton Island • 1; Sta. 18; 10°19.22’N, 109°13.38’W; rocks; suction pump, sediment under rocks; 55 m; 20.I.2005; J.-M. Bouchard, L. Albenga, L. Dugrais, leg. ECOSUR (anterior fragment twisted, tentacular and dorsal cirri lost, pharynx not exposed; dorsum brownish; fragment 8.5 mm long, 0.8 mm wide, chaetigers) .

DIAGNOSIS. — Pterocirrus with prostomium cordate, posterior margins entire, not projected posteriorly, median antennae inserted close to anterior margin; palps and antennae of similar size; dorsum with homogeneous pigmentation; acicular lobes of similar size; neurochaetae with handles smooth. Pharynx with abundant long papillae.

ETYMOLOGY. — The specific name is to honor Dr Jean-Marie Bouchard, a crustacean specialist who participated in the Clipperton Expedition, and was involved in sampling benthic samples, including the ones used for naming this species. The specific epithet is a noun in the genitive case ( ICZN 1999, Art. 31.1.2).

DISTRIBUTION. — Only known from the type locality, Clipperton Island, in subtidal rocky bottoms, 20-55 m depth.

DESCRIPTION

Body

Holotype (MNHN-IA-TYPE2046), juvenile with many dorsal cirri retained, pharynx almost completely exposed ( Fig. 5A ); body truncate anteriorly, wider by segment 20, tapered posteriorly; dorsum brownish, paler medially and posteriorly: body 9 mm long, 0.9 mm wide, 78 segments.

Anterior end

Prostomium cordate, distorted by everted pharynx, slightly bent posteriorly, barely wider than long, without anterior protuberance ( Fig. 5B ). Palps and antennae oblong tapered; palps and antennae of similar length, median antennae inserted close to anterior prostomial margin. Eyes large, brownish, subcircular, 1/3 as long as prostomial width. Posterior prostomial notch not seen. Segment 1 visible as a thin fusiform pigmented area. Nuchal organs not seen.

Pharynx

Pharynx exposed, including a smooth posterior enteric region, twice longer than pharynx, pharynx with abundant papillae ( Fig. 5B ), almost twice as wide as enteric portion. Each papilla 3-4× longer than wide, tapered, tips bent posteriorly. Pharynx aperture not seen.

Tentacular cirri

Tentacular cirri of segment 1 cirriform, reaching segments 9-10 (chaetigers 5-6); dorsal cirri of segments 2 and 3 cirriform, reaching segments 18-20 (chaetigers 14-16); ventral cirri of segment 2 with a large foliose projection, reaching segments 9-10 (chaetigers 5-6). Segment 3 without neuropodial lobes or chaetae. Segment 4 with neuropodial lobes and chaetae. Parapodia with dorsal cirri lanceolate, basally asymmetrical, mucronate, twice longer than wide, becoming slightly thinner in posterior segments ( Fig. 5D ). Supracicular lobes larger, more projected than infracicular ones ( Fig. 5C ), especially along anterior segments. Neurochaetae 12-15 compound spinigers per bundle; handles subdistally smooth (under 40 X enlargements), blades delicate, 20-25× longer than wide, denticulate, denticles larger basally. Ventral cirri oval, pointed, about twice longer than wide.

Posterior region

Tapered into a blunt cone; pygidium with anus terminal, anal cirri lost.

VARIATION

The holotype and three of the paratypes are juveniles (6.5- 9.0 mm long, 0.8-0.9 mm wide) showing brownish pigmentation dorsally and ventrally along anterior region in one paratype. One juvenile paratype (ECOSUR 278), slightly damaged ( Fig. 6A ), has darker intersegmental areas dorsally ( Fig. 6B ), and ventrally with pale midventral oval areas along a few anterior segments ( Fig. 6C ), following segments with a progressively smaller pigmented area. The largest paratype (MNHN-IA-TYPE2047) is a colorless, posteriorly incomplete mature female without tentacular or parapodial cirri ( Fig. 6D ) which also has intersegmental darker dorsal areas, but venter pale. This adult female is an anterior fragment (17 mm long, 1.9 mm wide), with oocytes floating in the coelomic parapodial spaces ( Fig. 6E ), each oval about 30-40 µm in length, and starting from about segment 40. Prostomial features such as eyes (size and pigmentation), as well as palps and antennae (size and insertion) are conservative, and show no modifications in the type material, although one antenna or cirrus were frequently missing. Because tentacular and dorsal cirri are dehiscent, their size-related modifications remain unknown; however, in the holotype dorsal cirri retain a similar shape throughout body, although they become slightly narrower along posterior segments. Neurochaetal numbers are somehow size-dependent because there are about 14 in smaller paratypes, and 22 in the largest one. In Pterocirrus species, neurochaetal handles look smooth, as indicated by Eibye-Jacobsen (1991), because they have a very short distal denticulated area.

REMARKS

Pterocirrus bouchardi n. sp. resembles P. montereyensis ( Hartman, 1936) described from central California, and recently redescribed by Pleijel et al. (2012), because they have a cordate prostomium, palps and lateral antennae of similar size, median antenna inserted close to anterior prostomial margin, eyes half as long as prostomial length, and segments dorsally smooth. These two species differ regarding the relative size of median to lateral antennae, dorsal cirri, and acicular lobes. In P. bouchardi n. sp. the median antenna is as long as lateral ones, dorsal cirri are tapered, without subdistal constriction, and acicular lobes are barely divergent, not separated from each other. On the contrary, in P. montereyensis the median antenna is smaller than the lateral ones, dorsal cirri are subdistally constricted, and acicular lobes are divergent, and medially separated from each other.

The reason why the juvenile was selected as the holotype is after it has the characteristic limbate ventral cirrus in chaetiger 2, whereas the adult specimen lost the cirri almost completely, and especially the diagnostic ones.

Figures

FIG. 5. — Pterocirrus bouchardi n. sp., holotype (MNHN-IA-TYPE2046): A, complete, dorsal view; B, anterior region, dorsal view; C, median chaetiger, right parapodium, without dorsal cirrus, posterior view (after Methyl green); D, posterior chaetiger, right parapodium, dorsal cirrus bent posteriorly, posterior view (after Methyl green); E, posterior region. Scale bars: A, 0.6 mm; B, 0.3 mm; C, D: 0.1 mm; E, 0.2 mm.

FIG. 6. — Pterocirrus bouchardi n. sp., paratypes: A, juvenile paratype (ECOSUR 278), without posterior region; B, same, anterior region, oblique dorsal view; C, same, oblique ventral view; D, largest paratype (MNHN), mature female, anterior region, dorsal view (tentacular and parapodial cirri lost); E, same, median chaetiger, left parapodium, anterior view with many oocytes (after Methyl green). Scale bars: A, 0.6 mm; B, C, D, 0.3 mm; E, 60 µm.