New species of hesionid and phyllodocid polychaetes (Annelida, Errantia) from Clipperton Island

ABSTRACT The study of marine annelids from oceanic islands has been problematic, especially because of the lack of infrastructure, or of easily accessible logistics for frequent expeditions. In this contribution, some specimens collected during the J.-L. Étienne Expedition to Clipperton Island in 2005, belonging to the families Hesionidae Grube, 1850 and Phyllodocidae Örsted, 1843 are newly described. Type material is deposited in the Muséum national d'Histoire naturelle, Paris, and a few others in El Colegio de la Frontera Sur, Chetumal. Hesionidae includes Psamathe charpyi n. sp. diagnosed by having eyes of similar size and neurochaetal blades 4-10 × longer than wide. In Phyllodocidae an assessment of the affinities within Phyllodoce Savigny in Lamarck, 1818 results in re-establishing its subgenera as distinct genera, and three species are newly described: Anaitides albengai n. sp., Nereiphylla etiennei n. sp., and Pterocirrus bouchardi n. sp. Anaitides albengai n. sp. is separated from more similar species by having the prostomium as long as wide, eyes ¼ as long as prostomial width, and basal pharynx region with 8-9 large papillae per row. Nereiphylla etiennei n. sp. differs from more similar species by having a rectangular prostomium, lateral antennae half as long as prostomial width, and ventral cirri barely longer than neurochaetal lobe. Pterocirrus bouchardi n. sp. separates from more similar species by having antennae of similar length, dorsal cirri tapered not distally constricted, and acicular lobes barely divergent. Keys are included for identifying all World species for each genus.


INTRODUCTION
In the Eastern Tropical Pacific, there are few studies concentrated on polychaetes from oceanic islands. Salazar-Vallejo (1989) included 65 species reported from the Revillagigedo Islands. Blake (1991)  Hesionid annelids are common in tropical environments; these annelids show diverging morphological patterns, one group having large, often colorful bodies with about 20 segments, whereas the other has smaller, brownish to pale bodies with many segments, and are sometimes associated with other invertebrates, especially echinoderms. Hesionids have a short, eversible pharynx that can have inner jaws for capturing their prey but feeding biology has been studied for only three species, out of 130, which emphasizes the need for additional field and lab studies on trophical ecology (Jumars et al. 2015;Salazar-Vallejo & Rizzo 2021).
On the other hand, phyllodocid annelids are present in all marine regions; most have long, thin colorful bodies with many segments, and are free-living in sandy or mixed bottoms. Phyllodocids produce abundant mucus and have long eversible pharynxes, whereas hardened structures are only known for a few species as denticulate papillae; their feeding biology has been documented for 12 species out of 400. They include carnivores, carrion-feeders, and one hydrothermal vent species sucking blood from other benthic annelids (Jumars et al. 2015;Villalobos-Guerrero et al. 2021). (2009) recorded no hesionids and two phyllodocid species from Clipperton Island: Eumida sanguinea (Örsted, 1843) originally described from Denmark, and Phyllodoce madeirensis Langerhans, 1880, originally described from Madeira. Dean et al. (2012) recorded four hesionid species including the Chilean Psamathe ancuda (Wesenberg-Lund, 1962), and four phyllodocid species, including P. madeirensis and Nereiphylla castanea (von Marenzeller, 1879) originally described from Japan.

Solís-Weiss & Hernández-Alcántara
In this contribution one hesionid and three phyllodocid species are newly described from Clipperton Island. For all genera, keys to all species in the world are also included.

Material and Methods
Specimens were collected during the J.-L. Étienne Expedition to Clipperton Island in 2005. Most stations were sampled by a team of scuba divers and sometimes using a suction pump for gathering specimens; the station and field data were listed by Poupin et al. (2009: 214-215). Type and non-type material is deposited in the Muséum national d'Histoire naturelle, Paris (MNHN) and El Colegio de la Frontera Sur, Chetumal (ECOSUR). The taxonomic treatment is given per family and then by genus/species in alphabetical order, with a slight variation for Phyllodoce-like genera. Small specimens were mounted on a drop of preservative fluid, and aligned, covered with a coverslip, and then alcohol-glycerol was added for measurements and observations in the compound microscope. Unless otherwise indicated, parapodial features included in the keys refer to median segments. Dimensions for phyllodocid body structures differ slightly from Teixeira et al. (2020: 226), because dorsal and ventral cirri length are taken as the longest distance between tip and base, not including the peduncle or ceratophore, whereas the size of eyes or lateral antennae is given as a fraction of prostomial width or length. Keys are mostly dichotomic; a few triple options were kept for brevity, 1984) from Florida, United States. On the other hand, Pleijel (1998) also regarded P. fusca and P. cirrata as synonyms, and Parapar et al. (2004: 232) followed it. However, despite the proximity of the type localities for these two species, both in the English Channel, there is no type material and topotype specimens for both species should be compared to corroborate this conclusion. There is one apparent difference regarding the length of ventral cirri according to the original descriptions, and some later illustrations (McIntosh 1908: pl. 69, fig. 16;Hartmann-Schröder 1996: 133, fig. 5b).
In P. fusca it is short, not reaching the tip of neurochaetal lobes, whereas in P. cirrata it is longer, reaching the tip of neurochaetal lobes. The key below regards them as different species based on this feature.

Posterior region
Unknown. Bergström (1914: 55-56) used and standardized 14 characters for revising the delineation and diagnosis for the phyllodocids. He proposed three new families, and among phyllodocids he proposed nine genera, six of which were regarded as valid by Fauchald (1977). Bergström (1914: 118) keyed out Anaitides Czerniavsky, 1882, Phyllodoce and Sphaerodoce Bergström, 1914 by using the shape and length of the tentacular cirri (oblong or tapered, long in the former two, against globular, short in the latter), and the arrangement of pharynx papillae on the basal region (forming rows in Anaitides, versus diffuse in the two others). Bergström (1914) also indicated he was partially following the Phyllodoce species groups proposed by Augener (1913b: 213-215), based on pharynx papillae pattern and dorsal cirri shape. To these features, Bergström added the shape of the ventral cirri for his key to Anaitides species (Bergström 1914: 139-140). Chamberlin (1919), and later Hartman followed Bergström and regarded Anaitides and Phyllodoce as separate genera throughout their publications;Fauchald (1977) included them as independent genera. Hartmann-Schröder initially regarded Anaitides and Phyllodoce as distinct genera, and later changed her mind and used subgenera in Phyllodoce.
Most authors, however, have preferred to regard them as subgenera. The first to provide explanations for this was Fauvel (1919: 357-359). Because of the problems with following Bergström formula for indicating the appendages of the first segments, especially for detecting the presence of chaetae, Fauvel rejected its use, although he emphasized (Fauvel 1919: 357) Bergström "gave a correct importance to pharynx features". Fauvel also indicated that "a more serious inconvenience of his classification was the multiplication of genera in a certainly abusive way" (Fauvel 1919: 358). He also added that "after more than 20 years, I reject this atomization of genera, completely useless in polychaetes where species are relatively few in each family" (Fauvel 1919: 359), and concluded: "However, in a genus including hundreds of species, the fractioning is more justified than in a genus having a small number of species, as is generally the case in polychaetes." This was Fauvel, and he was both very productive and very influential on other colleagues working on polychaetes. Regretfully, the morphological features of the anterior end and pharynx papillation patterns were not evaluated, despite the fact that in several other errant families, these attributes are useful for separating similar genera.
Pleijel (1991) made the first phylogenetic analysis of the Phyllodocidae. He studied 21 taxa and assessed 26 characters, but the shape of antennae and tentacular cirri was not included, and his character 9 combined basal and distal regions of the pharynx, but the basal region was not clarified regarding papillae patterns, as opposed to the distal region. Among his conclusions, Pleijel (1991: 238) listed seven genera or subgenera as junior synonyms of Phyllodoce: Anaitides; Aponaitides  , 1979;Paracarobia Czerniavsky, 1882, Protocarobia Czerniavsky, 1882, Phyllouschakovius Blake, 1988, Sphaerodoce, and Zverlinum Averincev, 1972. This synonymy reflects that some diagnostic features were disregarded, such that these taxa were regarded as similar under that perspective. Pleijel (1991Pleijel ( , 1993a hesitated about including Prophyllodoce Hartman, 1966 because he could not study the type material. This latter genus resembled Phyllodoce especially regarding the papillae pattern on the basal pharynx area, but the presence of two small dorsal tubercles on segment 1 was regarded as an additional pair of tentacular cirri, and used to separate it from Phyllodoce, as indicated in the original proposal (Hartman 1966: 182, key, 187, diagnosis). Pleijel (1991Pleijel ( , 1993b was correct. In a newly described species of Anaitides (see below), there are two dorsal tubercles on segment 1, but it matches the generic delineation for Anaitides. These so-called tubercles, or additional tentacular cirri, were regarded as nuchal organs (Gravier 1896: 341;Uschakov 1972: 123), and they are present in some species such as Phyllodoce laminosa (Pleijel 1991: 239, fig. 1 A, B), the type species of Phyllodoce. Consequently, the presence of nuchal organs cannot be enough to separate Prophyllodoce from Phyllodoce.

McCammon & Montagne
The other genera are very homogeneous regarding the development of prostomial appendages and tentacular cirri, but they were originally proposed as different genera by using differences in the tentacular cirri pattern, and pharyngeal features, especially the spatial arrangement of papillae, and sometimes additional parapodial characters. For example, Chamberlin (1919: 100) keyed out Anaitides, Phyllodoce and Sphaerodoce by using the type of tentacular cirri, and for the two former ones, the arrangement of pharynx papillae.
Pleijel (1991: 238) also indicated that "splitting this large genus is desirable but should be based on defining properties for all subgroups and will have to await further studies". Pleijel (1993b: 296, 298-299) returned to the problem and proposed recognizing three subgenera: Anaitides (incl. Aponaitides) with about 19 species, Phyllodoce (incl. Paracarobia and Sphaerodoce, perhaps Prophyllodoce) with about 21 species, and Zverlinum (incl. Phyllouschakovius) with three species. Most species could not be included in the above genera because "available specimens of many species are few and in poor condition" (Pleijel 1993b: 297).
The standardized diagnoses for these subgenera are modified from Pleijel (1993b: 296, 298-299). They are herein regarded as distinct genera because they present a unique combination of morphological features, which was confirmed in the later phylogeny (Pleijel 1993b). Diagnoses and incorporation of their type species (ICZN 1999, Art. 13.2.3) are as specified below. These taxa can be separated with the key given below. diagnosis. -Phyllodocids with prostomium with two oblong, tapered lateral antennae, median antenna usually reduced into a nuchal papilla. Four pairs of tentacular cirri, all oblong, tapered. Dorsal cirrophore without acicula; supracicular lobes blunt, as long as subacicular ones; ventral cirri medially widened. Pharynx with two regions; basal region usually completely covered by small round papillae, rarely with dorsal smooth areas.

reMarks
As indicated above, Prophyllodoce Hartman, 1966, with P. hawaiia Hartman, 1966 as its type species, has its basal pharynx area as in Phyllodoce, but there is one pair of lateral short tubercles in addition to the first pair of tentacular cirri on segment 1. Hartman (1966) regarded these tubercles as additional cirri, and Fauchald (1977: 48) regarded them as papillae, and recognized Prophyllodoce in his key to genera. However, Uschakov (1972: 123) indicated that "the additional pair of tentacular cirri on the first segment are… projecting nuchal organs, observed in some species of the genus Phyllodoce". After this, it can be noted that the next statement by Uschakov was wrongly translated because due to the presence of everted nuchal organs, the genus cannot key to Phyllodoce-like genera
reMarks Relevant features that help reinstate Sphaerodoce rely on the anterior part of the body. The type species, P. quadraticeps Grube, 1878 was described from the Philippines; it has a quadratic prostomium, and almost all its tentacular cirri, as well as lateral antennae and palps are all globular, whereas the prostomium is oval to cordate, and cirri are all subulate in Phyllodoce. Because these unique features were not included (shape of prostomium, shape of tentacular cirri), the type species groups with other species of Phyllodoce sensu stricto in the phylogeny by Pleijel (1993b). The papillae pattern on the pharynx was not described by Grube (1878). Gravier (1900Gravier ( : 1908 recorded P. quadraticeps for the Red Sea and observed the pharynx by dissection, and Day (1967: 146, fig. 5.2h) illustrated a specimen with a partially exposed pharynx. The pharynx is very long with abundant small papillae, but these Western Indian Ocean records might belong to a different species. Pleijel (1993b: 298) listed specimens deposited in several museums and regarded the papillation pattern of the basal pharynx area as dense and diffuse. Averincev, 1972reinstated Zverlinum Averincev, 1972.  diagnosis. -Phyllodocids with prostomium with two oblong tapered lateral antennae, median antenna often reduced to a nuchal papilla. Four pairs of oblong tapered tentacular cirri. Dorsal cirrophore with acicula; supracicular lobe digitate; ventral cirri tapered, not medially widened, sharp. Pharynx with two regions, basal region with irregularly distributed, multi-denticulate papillae, without smooth areas, distal region with round irregular tubercles.

Genus Zverlinum
reMarks Pleijel (1993b) indicated in the abstract that the type species, Austrophyllum monroi Hartman, 1964 was a junior synonym of Phyllodoce bulbosa Wesenberg-Lund, 1962, but no further details were incorporated in the publication. Austrophyllym monroi Hartman, 1964 was named after one specimen from South Georgia that Monro (1930: 74) had identified as Phyllodoce longipes Kinberg, 1865, and P. bulbosa was described from Central Chile. However, besides their type localities, there are certain morphological differences indicated in the original illustrations that would render such synonymy doubtful. For example, in A. monroi the prostomium is longer than wide, whereas it is wider than long in P. bulbosa, although this might be attributed to certain distortion due to pharynx eversion. The denticulate pharyngeal papillae illustrated for A. monroi were neither described, nor confirmed for P. bulbosa. Further, mid-body parapodia also differ. In A. monroi the dorsal cirri are longer than wide and supracicular lobes are very long, whereas in P. bulbosa cirri are as long as wide, and supracicular lobes are not so markedly projected. These differences might be explained because the parapodia were taken from different body regions. In any case, a re-examination of type or topotype material is required to corroborate the synonymy. diagnosis. -Phyllodocids with prostomium with two oblong tapered lateral antennae, median antenna often reduced into a nuchal papilla. Four pairs of oblong tapered tentacular cirri. Dorsal cirrophore without acicula; supracicular lobe usually blunt, as long as subacicular one; ventral cirri usually medially widened. Pharynx with two regions, basal region with large papillae, usually arranged in longitudinal rows, dorsal and ventral areas smooth (without papillae).
gender. -Feminine. After the code (ICZN 1999, Art. 30.1.4.4), the suffix -ides "is to be treated as masculine unless its author, when establishing the name, stated it had another gender or treated it as such by combining it with an adjectival species-group name in another gender form." Czerniavsky (1882: 159) listed the species for his new genus, newly transferred from Phyllodoce (feminine) and made no modifications for their corresponding suffixes, thus implying he regarded his new genus-name as having a feminine gender.
distribution. -The species of Anaitides have been described from shallow-water localities in tropical, temperate and polar seas. key to sPecies of anaitides czerniavsky, 1882 reMarks Pleijel (1993b: 295, fig 1G) regarded P. citrina Malmgren, 1865 as incertae sedis especially because it has less than 6 lateral rows of papillae per side on its pharynx basal region. More than six rows were documented for one Anaitides species (Day 1973: 22), as well as non-regular lateral rows for several other species (Hartmann-Schröder 1965b: 86;Gathof 1984: 19.33), and differences in the number of papillae per row (O'Connor 1987: 312). Further, in the new species described below, A. albengai n. sp., variations in the number of lateral rows were noted, and often in the same specimen there was a different number of rows along the left or the right side. However, the presence of smooth areas along dorsal and ventral surfaces are more regular and this explains why the midventral smooth surface is diagnostic, whereas the number of lateral rows is not. Consequently, P. citrina is included in Anaitides as indicated by Uschakov (1972: 130), and after the redescriptions by Pleijel (1988: 143), Dales (1991: 78), andPleijel (1993a: 35). For the key below, the descriptions or redescriptions were used to key out the species; sometimes, more than one morphological pattern has received the same name, and this explains why the same species name may be reached in two or more alternatives. They are included and might mean problematic records deserving further study. Likewise, the distribution area is incorporated but it does not mean the full distribution of the species.

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

Oocytes
Visible in parapodial spaces, especially abundant in median chaetigers; each about 50-60 µm in diameter.

variation
The nuchal organs are retracted if the pharynx is not exposed (Fig. 3A); they become visible after the pharynx is fully exposed (Fig. 3F). The eye shape varies from reniform to oval. Tentacular cirri changes with size; smallest specimens had their longest ones reaching chaetiger 2; they stabilize about reaching chaetiger 10 at 14 mm body length. The basal pharynx region is variable; it is often asymmetrical having regular rows on one side, and irregular ones on the other, and the number of rows varies from 5-6 regular ones to about 10 irregular ones. The dorsal surface is often smooth, but there can be up to 3-4 papillae in an irregular row. The ventral surface is always smooth. The dorsal cirri are narrower in anterior and posterior chaetigers, whereas they are slightly wider in median ones. The typical ciliary band in dorsal cirri are present along their posterior surface; staining helps making them more visible, but their length is progressively reduced in posterior chaetigers. It runs close to the inner margin as a straight band, running almost the entire length of the inner margin in median chaetigers (Fig. 3B, C), and becoming shorter and thinner in posterior chaetigers (Fig. 3D, E). Anal cirri are rarely present because the posterior region is delicate; if present, they are as long as the length from the last 2-3 chaetigers before the anus. reMarks Many authors preferred to use the junior synonym, Genetyllis Malmgren, 1867, over Nereiphylla. Among these authors is Day (1967), whereas others used first the older (Fauvel 1923) and later the younger names (Fauvel 1953). Some other authors regarded both genera as valid (Bergström 1914;Hartman 1959), being separated by having cylindrical versus depressed tentacular cirri. Pleijel (1991: 235) noted tentacular cirri are flatter in larger specimens of both genera and concluded they could not be kept separate on this single difference and regarded them as synonyms. For the key to species, the lists available in WoRMS (Read & Fauchald 2020a, b) were adjusted mostly after Pleijel (1991).
Nereiphylla etiennei n. sp. (Fig. 4) urn diagnosis. -Nereiphylla with prostomium rectangular, longer than wide; lateral antennae half as long as prostomial width; eyes 1/ 6-1/ 7 prostomial width; longest tentacular cirri reach chaetiger 5; dorsal cirri cordate, blunt, longer than wide; ventral cirri oval, blunt. reMarks Nereiphylla albovittata Grube, 1860 from the Adriatic Sea has not been found again, and it could not be incorporated in the key, but it can be keyed out by using keys in Fauvel (1923). Nereiphylla oculata (M'Intosh, 1885), described with hesitation as belonging in Genetyllis, from the Celebes Sea, does not belong in Nereiphylla. The specimen was slightly dried-out when McIntosh studied it, and he indicated it had several unique features. For example, the eyes resemble those present in alciopins, the tentacular cirri are displaced anteriorly and dorsally, such that they are arranged transverse to body length axis, and he also indicated the body wall differs from what is seen in other phyllodocids. Chaetae are compound falcigers, but nothing else could be indicative for its generic placement, and if its prostomial and tentacular cirri features are corroborated, it might represent an unknown group of bathypelagic polychaetes. The anterior end of the single specimen was subjected to histological sectioning for illustrating fine details of eyes, although it was referred to as N. lutea (Malmgren, 1865) in the following page with a contribution by Marcus Gunn on the eyes and cephalic ganglion. In any case, being it a confusion of the species name, or a detailed study based on the Scandinavian species, fresh specimens from the Celebes Sea are needed to clarify its affinities.  width throughout fragment, 2.7 mm long, 0.3 mm wide, 33 chaetigers. Prostomium rectangular, slightly longer than wide (Fig. 4A). Lateral antennae and palps oblong tapered, of similar length, half as long as prostomial width (Fig. 3B); without median antenna.
Eyes dark brown, about 1/ 7 as long as prostomial width. Posterior prostomial notch not seen, a paler area visible, but not depressed. Segment 1 completely reduced dorsally. Nuchal organs not seen.   Pharynx Pharynx partially exposed in paratypes (Fig. 4B), brownish, as long as first 6 segments; surface completely covered by globular papillae, in alternating rows, each papilla slightly longer than wide; 8-9 larger papillae in aperture.

Posterior region
Visible in one paratype (Fig. 4D) tapered into a blunt cone; pygidium with anus terminal, anal cirri 2-3× longer than dorsal cirri of previous chaetigers, lanceolate, with long tips and abundant brownish globular glands.
variation Pigmentation varies, with the anterior region often paler than median and posterior ones. Globular pigmented glands vary in abundance along body; dorsum often with a transverse band with abundant to sparse glands, and in paler segments often one pair of pigmented glands are visible one on each side, close to parapodial bases. The prostomial shape is not modified after pharynx eversion. Dorsal cirri are longer and with tips better defined along anterior chaetigers, but in median and posterior chaetigers they become shorter and with tips less defined. One of the paratypes (ECOSUR) has spermatids in parapodial coelom and although the other specimens were not dissected, they are regarded as mature organisms, not juveniles despite their small size.
reMarks Nereiphylla etiennei n. sp. resembles what Gardiner (1976: 113, Fig. 7h-k) recorded from the Northwestern Atlantic as N. castanea (von Marenzeller, 1879). These two species have prostomium longer than wide, eyes 1/ 6-1/ 7 as long as prostomial width, longest tentacular cirri reaching chaetiger 5, dorsal cirri cordate, longer than wide, and ventral cirri oval, blunt. These species differ especially because in N. etiennei n. sp. the prostomium is rectangular, lateral antennae are half as long as prostomial width, and ventral cirri are barely longer than neurochaetal lobe, whereas in Gardiner's specimens the prostomium is oval, lateral antennae are 1/3 as long as prostomial width, and ventral cirri are longer than neurochaetal lobes. On the other hand, N. castanea has been recorded from many different localities throughout the world. Some of the records include descriptions and illustrations such that they were regarded as different from the typical form in the key above, as redescribed by Izuka (1912: 199, Pl. 21 , Fig. 3). These differences deserve a further study to clarify their relevance and if confirmed, they should be regarded as distinct species. This, however, is beyond the objective of this contribution.
distribution. -The species of Pterocirrus have been described mostly from shallow-water localities from tropical, temperate and polar seas.
reMarks Pterocirrus Claparède, 1868 was proposed as a subgenus in Eulalia Savigny, 1822, and it was regarded as an independent genus by Michaelsen (1892: 103), de Saint-Joseph (1895: 226), and Ehlers (1904: 17). However, Bergström (1914 regarded it as a junior synonym of Sige Malmgren, 1865. His conclusion was surprising because of three facts. First, Sige lacks winged ventral cirri in segment 2, which were used for naming the subgenus as Pterocirrus. Second, Sige has digitate, markedly projected supracicular lobes, which are not so projected in Pterocirrus. Third, in Sige the pharynx appears smooth, but in Pterocirrus it was characterized as having abundant large, blunt papillae by McIntosh (1908: 62).
As part of his monograph on Northwestern Pacific polychaetes, Uschakov (1972: 151) included a key to phyllodocid genera, reinstated Pterocirrus as an independent genus, and provided a diagnosis and a key for identifying its species. Uschakov's proposal was followed by Banse (1973), Banse &Hobson (1974), andFauchald (1977). Pleijel (1991) analysed  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.

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.

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.