Revision of Flabelliderma Hartman, 1969 (Polychaeta: Flabelligeridae)

The flabelligerid genus Flabelliderma Hartman, 1969 is redefined and its type species is re‐established. In comparison with Flabelligera Sars, 1829, the diagnostic features include the fusion of papillae forming tubercles, often adhering sediment particles, and notopodial lobes forming large ovoid lobes. Four species are described and presented as new combinations, and three others were previously undescribed; thus the species included are F. papillosa (Essenberg, 1922) from southern California, F. berkeleyorum n. sp. from Washington, F. claparedei (de Saint‐Joseph, 1898) from the Bay of Biscay, F. gourdoni (Gravier, 1906) from Antarctica, F. lighti n. sp. from Guadalupe Island, western Mexico, F. ockeri n. sp. from southern California, and F. pruvoti (Fauvel, 1930) from New Caledonia.

The members of these two genera have three main modifications of the anterior end, in comparison with the other flabelligerid genera: (1) the chaetae of the first chaetiger, or cephalic cage, are arranged in a transverse line, making an almost complete circle around the head; (2) the head region, which includes prostomium, peristomium, nephridial lobes, and branchiae, is rarely eversible-there seems to be a direct relationship between the length of the eversible head region and the size of the cephalic cage chaetae; the region covering the eversible head is the cephalic hood; and (3) the neurohooks are explain its etymology, but she was obviously stressing this skin difference. Flabelliderma has been restricted by Light (1978) such that now it is regarded as a monotypic genus.
In this contribution, the type species for Flabelliderma is re-established, and the genus is redefined based upon a revision of several species previously included in Flabelligera. By sharing notopodial lobes with globular papillae, dorsal tubercles of varying length, and neurohooks with articulated handle and blunt entire crest, they are redescribed and transferred to Flabelliderma. A key to all species is also included. The revision and delineation of Flabelligera are part of another forthcoming contribution but the species therein included do not form an homogeneous group.

Material and methods
All materials were studied with ordinary light microscopy, and specimens of two species were studied alive. Preserved specimens were washed in a 50/50 mixture of commercial vinegar and 70% ethanol to remove adsorbed or foreign materials; some were temporarily stained by placing them for a few seconds in an oversaturated solution of methyl green in 70% alcohol. Photographs were made with digital cameras and photos were employed to prepare the plates. Most figures are based on a series of photographs with a selection of the best areas, and then pasted together. This has been preferred over line-drawings because it illustrates the features as they really are and not what the illustrator thinks that they should be. Unless otherwise stated, body length does not include the anterior long chaetae, and body width does not include notochaetae. Abbreviations for figures b, branchia; bs, branchial scars; c, caruncle; dl, dorsal lip; ll, lateral lip; nl, nephridial lobe; pl, palp lobe; ps, palp scar; vl, ventral lip.
Type species. Stylarioides papillosa Essenberg, 1922, reinstated. Diagnosis (emended) Body papillae abundant, usually grouped forming dorsal and lateral tubercles, making elongate thick notopodial lobes, free from from the rest of the body. Cephalic hood reduced. Branchiae cirriform, sessile on a branchial plate, arranged in two lateral groups. Nephridial lobes placed medially on the branchial plate, separated from the branchiae. Parapodia lateral, homogeneous. Notopodial lobe thin or ovoid, often including globular or vesicular papillae. Neurohooks multiarticulated; handle articulated, crest entire. Free-living in rocky or mixed bottoms, rarely symbiotic with sponges. Hartman (1961, p 118) proposed Flabelligera essenbergae as a replacement name for Stylarioides papillosa Essenberg, 1922; in her catalogue, she had regarded this name as a secondary junior homonym of Siphonostomum papillosum Grube, 1840, described from the Mediterranean Sea (Hartman 1959, p 416). However, Siphonostoma papillosum was regarded, in turn, as a questionable synonym of Flabelligera affinis Sars, 1829, or Pherusa monilifera delle Chiaje, 1831 (Hartman 1959, p 420) which are very different genera. However, she had regarded Stylarioides papillosa (Grube) as a member of Flabelligera (Hartman 1959, p 421), but based on the study of type material, this conclusion is incorrect.

Discussion
This confusion was due to the fact that Grube (1850, p 320) regarded his species as a junior synonym of Siphonostoma diplochaitus Otto 1821, which belongs in Flabelligera. However, Grube himself later solved the problem by regarding his species as a junior synonym of Stylarioides monilifer, which was commented upon several times in his revision (Grube 1877, p 60, 67, 71). Further, this synonymy was repeated by Fauvel (1927, p 118); unfortunately these synonymy statements were overlooked by Hartman. Therefore, Siphonostomum papillosum Grube, and Stylarioides papillosa Essenberg are not congeneric, and following Article 59.4 (International Commission on Zoological Nomenclature (ICZN) 1999), this should be resolved. Thus, the solution should involve a new combination for the original name, instead of a replacement name, the original name should be used as the type species of the genus, and Flabelliderma essenbergae Hartman, 1961, must be regarded as a junior objective synonym of Stylarioides papillosa Essenberg, 1922 (see below).
Flabelliderma contains only two species after Hartman's key (1969, p 286): F. essenbergae and F. commensalis. She noticed the large notopodial development in what she regarded as the type species, although neuropodial alignment is very different as well. Later, Fauchald (1977, p 116-117) presented the genus as monotypic, with Flabelligera commensalis Moore, 1909, as the type species, and added a diagnostic feature improving the original definition to: ''body papillae with thick mucus and encrusted with debris''. Light (1978, p 682-685) noticed these confusions, brought back F. commensalis to Flabelligera, and emended the generic definition stressing the long pedunculate and vesicular papillae, as well as the enlarged notopodial lobes. This definition is partially followed here, but F. commensalis does not fit in Flabelligera because its neuropodia are placed very close to the midventral line, and because of its symbiotic habit. This issue will be documented elsewhere.
Thus, in comparison with Flabelligera, the main diagnostic features for Flabelliderma are that individual papillae, or their groups, are easily seen because they make sediment-loaded tubercles, and by the large notopodial lobe development, often with large vesicular papillae. As currently redefined, the genus includes Flabelliderma papillosa (Essenberg, 1922) n. comb., F. berkeleyorum n. sp., F. claparedei (de Saint-Joseph, 1898 n. comb., F. gourdoni (Gravier, 1906) n. comb., F. lighti n. sp., F. ockeri n. sp., and F. pruvoti (Fauvel, 1930) n. comb. Three additional new species are described: F. berkeleyorum n. sp. collected while swimming in Friday Harbor, Washington, F. lighti collected in a shallow subtidal sponge in Guadalupe Island, and F. ockeri collected in dead giant kelp holdfasts, a species that has previously been identified as F. essenbergae (i.e. F. papillosa).

Diagnostic features
On the basis of this redefinition, Flabelliderma is not monotypic and certainly it is far from being a well-known genus. Since there are species collected in tropical, temperate, or polar environments, many more species might remain undescribed. The following are the main diagnostic features for the species in the genus.
Body papillae. There are several differences in body papillae among different Flabelliderma species. Individual papillae are lageniform, often provided with long stems and sometimes carry a long mucro. Most species adhere sediment particles on each individual papillae; these particles are mostly fine, loosely adhered to the papillae but sometimes they form dehiscent clavate sediment tubercles, with abundant sediment (Figures 1B, C, 2D, 3A, D, 5A, B), or with little sediment ( Figure 4A-C), or stiff rectangular tubercles, especially dorsally ( Figure 6A, B, D). The only exception is F. pruvoti, because their papillae are spherical or with a tiny mucro, and are mostly sediment-free ( Figure 7A-C). Dorsal papillae are often fused forming large sediment tubercles or masses and their relative number per transverse line, along a median segment, is given to clarify specific features.
Notopodial lobes. The notopodial papillae fuse to each other forming notopodial lobes, which often include globular or vesicular papillae. This term refers to their position, but it must be kept in mind that they are not body wall outgrowths from the notopodia; they are rather a complex construct of notopodial papillae. The notopodial lobes might be thin or ovoid (Figures 2A, B, E, 3D, 4C, 5D, 7A-C), or more or less funnel-shaped or distally expanded ( Figure 5D). They may also differ in the relative amount of sediment adhered on individual papillae; thus, those having sediment restricted to their bases give a pilose or ''hairy'' appearance to the lobes (Figures 4B, C, 5D). However, if the papillae are spherical, with a long stem but without mucro, the sediment will be very sparse and the notopodial lobes will appear clean ( Figure 7C).
Notochaetae. All notochaetae are covered by the notopodial lobes. There may be some variations in their number, in the type of articulation, or in the relative size of the articles along the chaetae. The number of notochaetae may be size-dependent and probably of limited usage. However, the pattern of articulation might be more specific, although some chaetae have articulations better defined or extended throughout its length. Thus, the articles can be short if they are wider than long, medium-sized if they are as long as wide, and long if they are longer than wide. Further, the articulation size varies among the chaetae and this feature is useful.
Neurohooks. Neurohooks can be divided in two parts. The exposed portion includes the distal piece, or crest, which is often thin and curved; in most species it is tapering and sharp, and rarely it can be medially expanded and blunt ( Figure 7D). The handle is not exposed and it is multiarticulated; the articulations will be referred to as short, if they are wider than long, medium-sized if they are as long as wide, and long if they are longer than wide. The number of long articles in the median region, as well as their relative length, differs among species, and there is a tendency to become shorter and poorly-defined towards the crest. The relative size and degree of pigmentation of the crest varies along the body; anterior or posterior neurohooks are more delicate, and slightly less pigmented, than those present in median chaetigers.
Anterior end and branchial structure based on neoparatypes. Prostomium high cone with four dark-reddish large eyes. Caruncle well developed, lateral keels elevated, thin, median one wider, swollen. Palps long, tips eroded; palp bases rounded, small. Lips damaged. Branchiae mostly lost; each lateral group with about 40 scars. Nephridial lobes long, one lost, as long as palps, placed towards the dorsal margin, separated from the branchiae ( Figure 1C).
Cephalic cage chaetae as long as one-ninth body length, densely covered by papillae, difficult to count. Anterior dorsal margin of first chaetiger with long papillae (mostly damaged). Anterior chaetigers without especially long papillae, with large vesicles. Chaetigers 1-3 of about the same length. Chaetal transition from cephalic cage to body chaetae abrupt, neurohooks present from chaetiger 2. Gonopodial lobes not seen.
Parapodia well developed, placed on the body corners ( Figure 1D); median neuropodia ventrolateral. Notopodial lobes ovoid with rough surface. Dorsal sediment tubercles about as long as notopodial lobes, mostly of a single size; soft, made by loosely packed large globular papillae; most papillae ovoid, with a short nipple-like distal projection. Some large vesicular papillae separated from the lobes. Neuropodia shorter lobes, masked by elongate papillae almost completely covering the neurohooks.
Median notochaetae arranged in a short transversal line; four to five multiarticulated capillaries per bundle, as long as two-thirds body width, with short articles basally and medially, longer distally. Neurochaetae multiarticulated hooks from chaetiger 2, mostly a single hook per ramus. Handle articulation with three longer articles medially, becoming progressively longer, distal articles shorter. Crest darker, tapering, acute, slightly curved distally ( Figure 1E). Posterior end tapering; pygidium with anus terminal (as seen in neoparatypes), without anal cirri, or pigment, rarely pale brownish.

Discussion
Essenberg (1922) did not designate type material and his single specimen is lost. When Hartman (1961) changed the original name and redescribed the species, she failed to designate any of her three specimens as types, but her materials belong elsewhere (see below). Later, Light (1978) regarded two of Hartman's specimens as syntypes, which cannot be the case because they were not employed for the original description, but did not recognize any of them as neotypes. He further expanded the species definition by introducing some rather different specimens under the same species name. Thus, in order to avoid any instability in the usage of the species name, a neotype and neoparatypes are herein designated. The specimens come from about 0.3u north from the type locality (San Diego, California), and were found in the same type of environment (subtidal, eelgrass roots). The other specimens indicate that size can be 8-26 mm long, with 25-27 chaetigers.
In introducing Flabelligera essenbergae as a new name, Hartman (1961, p 338) stated that ''The specific name is preoccupied (Hartman 1959, p 416) and here replaced with one in honor of the first describer''. However, she was not aware that her materials differ from the original ones in at least one basic and relevant feature: the dorsal tubercles are different. In F. papillosa they are ''long, finger-shaped, attached to the body by a narrow neck'' (Essenberg 1922, p 379), while Hartman (1961) provided no details of the dorsal papillae, but her illustrations show they are larger, thicker, less abundant, and with a very wide base. Therefore, F. essenbergae becomes a junior subjective synonym, because it was introduced as a replacement name, and a new name is required for the other form (see below).
Flabelliderma papillosa n. comb. is closely allied to F. lighti n. sp. by having dorsal and lateral clavate tubercles. They differ in the relative size of dorsal sediment tubercles in comparison with the notopodial lobes, and in the relative number of dorsal sediment tubercles per transverse row on each segment. In F. papillosa the dorsal sediment tubercles are larger, as long as notopodial lobes, and they are less abundant than in F. lighti n. sp. On the other hand, F. papillosa resembles F. claparedei (de Saint-Joseph, 1898) n. comb. because they have dorsal clavate sediment tubercles; however, they differ in the relative size of their tubercles. Thus, they are of a single size in F. papillosa while they are of two different sizes in F. claparedi.

Distribution
From Monterey to San Diego, California, in subtidal kelp holdfasts, seagrass root masses, and in shallow sandy bottoms (20 m).
Anterior end observed in one paratype. Prostomium a low cone, with four fading eyes. Caruncle well developed. Palps white, thick, slightly longer than branchial filaments; palp bases low, rounded. Lateral and dorsal lips fused, laterals massive, ventral lip reduced. Branchial groups with filaments arranged in 15 rows, each with two to five filaments, about 40 filaments per group; longest shorter than palps. Nephridial lobes large, base rounded, tips rounded, placed above the level of the eyes ( Figure 2C).
Cephalic cage chaetae as long as one-seventh body length or as long as body width; about 70 per fascicle. Anterior dorsal margin of first chaetiger papillated. Anterior chaetigers without especially long papillae. Chaetigers 1-3 slightly decreasing in size posteriorly. Chaetal transition to body chaetae abrupt; neurohooks present from chaetiger 2. Gonopodial lobes not seen in holotype (one paratype with whitish short, rounded lobes in chaetigers 5-6). Parapodia well developed, lateral; median neuropodia ventrolateral. Notopodial lobes cylindrical, thin, soft, surface regularly slightly nodulose, made by closely packed globular papillae ( Figure 2D, E). Dorsal sediment tubercles rounded, smaller than notopodial lobes, all of about the same size. Neuropodia projected lobes, carrying lageniform papillae but no globular papillae.
Median notochaetae arranged in a short transverse line; multiarticulated capillaries with short articles basally, longer medially and distally; about five notochaetae per bundle; chaetae about two-thirds as long as notopodial lobe or about two-thirds as long as body width. Neurochaetae multiarticulated hooks from chaetiger 2, one per ramus. Handle articulation with short articles basally, three to four longer ones medially, then progressively shorter. Crest darker, subbasally wider, blunt, markedly curved distally ( Figure 2F). Posterior end as a rounded lobe; pygidium with anus pale, terminal, no anal cirri.

Discussion
Flabelliderma berkeleyorum n. sp. resembles F. ockeri by having short sediment dorsal tubercles. They differ especially in the relative size of the tubercles, being larger, more or less rectangular in F. ockeri while they are short, rounded in F. berkeleyorum.
This species was caught because they were swimming and were attracted to a light (Berkeley and Berkeley 1960). Swimming or swarming members of Flabelligera have been recorded on at least three other occasions. The first record was made by Sorby (1906, p 437;McIntosh 1915, p 112); he found that F. affinis was swimming abundantly during several years and that this abundance lasted for a few years. Sorby thought that while swimming, the adults may release their gametes. The second record was made by Gravier and Dantan (1928, p 159-160); they collected some specimens with a light trap in February and June in the Mediterranean but they were small specimens. In the third report, Herpin (1929, p 86-87) noticed many small specimens without sexual products, but in July, he found large males which released sperm when placed in flasks with sea water, and concluded that swarming may be made by just a few individuals. The fourth record was made by Berkeley and Berkeley (1960, p 792-793); they noticed five Flabelligera specimens collected with a light in Friday Harbor. They indicated that they were sexually mature and spawning; about their specific identity, they found it closer to F. affinis than to F. infundibularis, which is common in the region. However, although there are some morphological differences that might be related to reproductive transformation or epitoky, this is unlikely since there are no different chaetae and at least in the holotype there remain many dorsal sediment tubercles. Further, there were no ova in the specimens; thus, either they had spawned completely or the spherules found were rather detached dorsal sediment tubercles. It is noteworthy that Pettibone (1954, p 289) noticed that when the specimens appear in the water column, they lack any transparent tunic. This might indicate that they could be members of Flabelliderma, rather than Flabelligera, as was the case for these specimens from Friday Harbor.

Etymology
This species is named to honour the life and work of the late Edith and Cyril Berkeley. They made many relevant publications on Canadian polychaetes, especially on those living along the Pacific coast, and also made some contributions to the study of more southern polychaetes, including those living in Mexican waters.

Type locality
Friday Harbor, Washington.

Distribution
Northeastern Pacific coasts but apparently restricted to the type locality, although it might have been confused with the other common species there, Flabelligera infundibularis Johnson, 1901.

Additional material
Four specimens, three compressed, another one dried out (MNHN-448) collected in the same locality, 27 July 1908, A. de Saint-Joseph, coll. One specimen (MNHN-449) collected in the same locality, 30 July 1900, A. de Saint-Joseph, coll.
Median notochaetae arranged in a short transverse line; 12-14 multiarticulated capillaries per fascicle, about as long as body width, with articles long, basally and medially, becoming slightly shorter distally. Neurochaetae multiarticulated hooks from chaetiger 2, one hook per ramus. Handle articulation with three longer articles medially, first shorter, two others of about the same length; more distal articles shorter. Crest darker, tapering, acute, only tip markedly curved ( Figure 3E). Posterior end tapering distally, truncated; pygidium with anus terminal, as a rounded muscular lobe; no anal cirri.
In the original description, there were detailed measurements of article length in each type of chaetae, but little information about the general aspect of the worm. However, there were two statements that are indicative of this new generic placement; de Saint-Joseph (1898, p 363) stated that the worm had sediment on the outer cuticle: ''…entourné d'une couche épaisse de mucus melangée de sable et de vase…'' and that it had notochaetal lobes with globular papillae, some with a distal lobe, with long stems (1898, p 364, Plate 21, Figures  178, 179): ''Les papilles qui accompagnent les soies sont lagéniformes ( fig. 176); les autres ont 3 formes différentes: 1u en massue ( fig. 177); 2u sphérique (fig. 178); 3u sphérique surmountée d'une pointe cylindrique.'' However, the holotype had been manipulated too much and most papillae and sediment tubercles were removed; so, for the original description, these features were based on a curled specimen that had not been brushed before.
Because of the shape of the dorsal tubercles Flabelliderma claparedei (de Saint-Joseph, 1898) n. comb. resembles F. papillosa and F. lighti n. sp; however, F. claparedei differs by having dorsal sediment tubercles of two different sizes, and its notopodial lobes are foliose, instead of cylindrical or globose, as is the case in the other species. The original name employed by de Saint-Joseph, ''claparedii'' must be modified since it was formed after Edouard Claparède, it must be claparedei.

Distribution
Only known from the type locality, St. Jean de Luz, southwestern France, in rocky shores.
Median notochaetae arranged in a short transverse line; eight to nine multiarticulated capillaries per fascicle, as long as one-fourth to one-third body width, with articles long basally and medially, becoming shorter distally. Neurochaetae multiarticulated hooks from chaetiger 2. Handle articulation with two longer articles medially, proximal article about half as long as distal one, more distal articles shorter. Crest slightly darker, tapering, tip blunt, curved distally ( Figure 4E).
Posterior end tapering ( Figure 4C); pygidium with anus terminal, short muscular ring, no anal cirri. One specimen collected in May (SMNH-55733) had ova of about 125 mm. Another specimen (MNHN-A184) has two parasite egg-masses in the cephalic area ( Figure 4F); one is complete, oval, 1 mm long with about 10 eggs in line; another one broken. In both cases there is a thin membrane and a very thin, transparent, short peduncle attaching it to the flabelligerid anterior end.

Discussion
Flabelliderma gourdoni (Gravier, 1906) n. comb. is unique in having hirsute notopodial lobes, which is due to the fact that their papillae have long mucrones and they are sediment-free. It includes F. pennigera Ehlers, 1908; the latter was described on the basis of having notochaetal lobes resembling feathered projections, which is precisely the diagnostic feature for F. gourdoni. On the other hand, F. pennigera was described as having neurohooks from chaetiger 3, not from chaetiger 2 as is the case in F. gourdoni. However, the second parapodia are ventrally displaced, giving the impression that first neurohooks appear in chaetiger 3, when the adjacent notochaetae are regarded as second chaetiger neurochaetae.

Distribution
Besides the type locality, it has been recorded in Antarctic and subantarctic areas in deep water (76-385 m).

Type material
Eastern Pacific Ocean: holotype (CAS-168303) collected in Old Sealer's Cove (Old Sealer's Station), southeastern side of Isla Guadalupe (28u539N, 118u189W), Mexico, miscellaneous scrapings in low intertidal, associated with yellow sponge that turned red purple in preservation, staining the polychaete, 1 January 1975, W. L. Lee and A. J. Ferreira, coll.
Prostomium high cone with four dark eyes (not clearly seen against the red purple colour). Caruncle present, wide basally, medially elevated, projected dorsally. Palps missing; palp bases rounded, large. Branchial groups with about 40 filaments. Two nephridial lobe scars, placed towards the dorsal margin, separated from the branchiae ( Figure 5C).
Cephalic cage chaetae short, one-twelfth as long as body or two-thirds as long as body width (excluding notopodia); chaetae densely covered by papillae, difficult to count. Anterior dorsal margin of first chaetiger without papillae, probably eroded. Anterior notopodia without especially long papillae. Chaetigers 1-3 of about the same length. Chaetal transition from cephalic cage to body chaetae abrupt, neurohooks present from chaetiger 2. Gonopodial lobes not seen.
Parapodia well developed, placed on the body corners; median neuropodia ventrolateral. Notopodial lobes ovoid, rough projections, made by loosely packed globular papillae. Dorsal sediment tubercles thin, smaller than notopodial lobes, mostly of a single size; soft ( Figure 5D). Most papillae cylindrical, with long distal nipplelike projections. Some large globular papillae outside the notopodial lobes. Neuropodia shorter lobes, masked by elongate papillae almost completely covering the neurohooks.
Median notochaetae arranged in a transverse short line, tips not exposed, four to five multiarticulated capillaries per bundle, as long as half body width, with short articles basally and medially, longer distally. Neurochaetae multiarticulated hooks from chaetiger 2, mostly a single hook per ramus. Handle articulation with three longer articles, proximal one shorter, the others slightly longer. Crest darker, tapering, acute, slightly curved distally ( Figure 5E).

Discussion
Some of the specimens herein regarded as members of Flabelliderma lighti n. sp. and F. ockeri n. sp. were included by Light (1978) in F. essenbergae, which is a junior synonym for F. papillosa. These two species are different regarding the dorsal sediment tubercles, since they are soft, clavate, pedunculate in F. lighti n. sp., while they are stiff, with a wide base and sessile in F. ockeri n. sp. Flabelliderma lighti n. sp. is closely allied to F. papillosa. As stated above, they differ in the relative size and number of dorsal sediment tubercles. In F. lighti they are smaller than the notopodial lobes and more abundant per segment, while in F. papillosa they are at least of about the same size as the notopodial lobes and less abundant per segment. Further, they come from different environments: F. lighti was associated with a low intertidal sponge, collected on a rocky shore, while F. papillosa is free-living in mixed bottoms, in crevices, in intertidal or subtidal depths.

Etymology
This species is named after William J. Light, who made important publications on spionids and maldanids, and especially solved some problems in the taxonomy of flabelligerids.

Distribution
Currently only known from the type locality in shallow subtidal rocky shores in Guadalupe Island, Mexico, associated with a yellow sponge.
Cephalic cage chaetae one-ninth as long as body length, or half as long as body width (excluding notopodia); chaetae densely covered by papillae, difficult to count. Anterior dorsal margin of first chaetiger with long papillae (smooth after their removal in neotype). Anterior notopodia without especially long papillae. Chaetigers 1-3 of about the same length. Chaetal transition from cephalic cage to body chaetae abrupt, neurohooks present from chaetiger 2. Gonopodial lobes not seen.
Parapodia well developed, placed on the body corners ( Figure 6D); median neuropodia ventrolateral. Notopodial lobes funnel-shaped, distally widened or ovoid with rough surface. Dorsal sediment tubercles smaller than notopodial lobes, of variable size; stiff, made by closely packed papillae and sediment. Some large vesicular papillae projecting out from the notopodial lobe. Neuropodia shorter lobes, masked by elongate papillae almost completely covering the neurohooks.
Median notochaetae arranged in a transverse short line; multiarticulated capillaries with articles poorly defined basally and medially, better defined distally, rapidly increasing their length, five to six per bundle, as long as half body width. Neurochaetae multiarticulated hooks from chaetiger 2, mostly a single hook per ramus. Handle articulation with two longer articles medially, proximal one less than half as long as next one, more distal articles shorter. Crest darker, wider medially then tapering, acute, markedly curved distally ( Figure 6E). Posterior end tapering; pygidium with anus terminal, without anal cirri.

Discussion
Flabelliderma ockeri n. sp. is the only species in the genus that forms stiff, widely-based, dorsal sandy tubercles.

Etymology
This species is named after Mr. David Ocker, in recognition of his long-standing generous support to polychaete workers, most having come from Chetumal. Thanks to his support, many extremely productive research visits have been made to Los Angeles.

Type locality
Corona del Mar, California.

Distribution
Southern California, low intertidal in rocky bottoms, in seagrass root masses, kelp holdfasts, or under rocks up to 12 m depth. The dead kelp holdfast, where some specimens were taken from, was 3-4 months old (S. Anderson, personal communication, 2004).

Description
Holotype  complete, greyish, slightly damaged, cylindrical, with long, whitish, cylindrical notopodial lobes ( Figure 7A, B). Body densely papillated; papillae small, capitate, globose, very abundant dorsally (eroded in holotype; 40-50 per segment in paratype), smaller laterally, tiny ventrally. It is 32 mm long, 3 mm wide (including notopodia 7 mm), cephalic cage 2 mm long, 42 chaetigers. Prostomium a low cone, with four dark eyes. Caruncle well developed. Palps white, thick, as long as branchial filaments; palp bases low, rounded. Lateral lips massive; ventral and dorsal lips reduced. Branchial groups with filaments arranged in 12 rows, each with three to five filaments, about 40 filaments per group; longest as long as palps. Nephridial lobes large, base foliose, tips missing, placed at the same level as the eyes.
Cephalic cage chaetae as long as one-fifteenth body length or two-thirds body width (most damaged in holotype); about 60 chaetae per side. Anterior dorsal margin of first chaetiger papillated. Anterior chaetigers without especially long papillae. Chaetigers 1-3 of about the same length. Chaetal transition from cephalic cage to body chaetae abrupt; neurohooks present from chaetiger 2. Gonopodial lobes not seen.
Parapodia well developed, lateral; median neuropodia ventrolateral. Notopodial lobes cylindrical, soft with surface smooth, made by closely packed globular papillae ( Figure 7C). Large dorsal sediment tubercles absent; dorsal papillae smaller than notopodial lobes, all of the same size. Neuropodia projected lobes, carrying globular papillae, less densely packed, but each papilla larger, ovoid or club-shaped.
Median notochaetae arranged in a short transverse line; multiarticulated capillaries with very short articles basally and medially, become longer distally; about five notochaetae per bundle; chaetae about two-thirds as long as notopodial lobe or about two-thirds as long as body width. Neurochaetae multiarticulated hooks from chaetiger 2, one per ramus (rarely two). Handle articulation without long articles, most articles short, poorly defined. Crest darker, basally wider, then tapering, blunt, markedly curved distally ( Figure 7D). Posterior end as a rounded lobe; pygidium with anus darker, dorsoterminal, no anal cirri.

Discussion
Flabelliderma pruvoti (Fauvel, 1930) n. comb. differs from other species in the genus because it has very small dorsal papillae. The record of a hirsute articulation in the neurohooks by Fauvel (1930, Figure 8d) is explained as the breakage of the oblique chaetal filaments.

Distribution
Only known from the type locality, Île de Pins, New Caledonia.
Key to species of Flabelliderma Hartman, 1969, redefined