Segmented worms (Phylum Annelida): a celebration of twenty years of progress through Zootaxa and call for action on the taxonomic work that remains.

Zootaxa has been the leading journal on invertebrate systematics especially within Annelida. Our current estimates indicate annelids include approximately 20,200 valid species of polychaetes, oligochaetes, leeches, sipunculans and echiurans. We include herein the impact of Zootaxa on the description of new annelid species in the last two decades. Since 2001, there have been over 1,300 new annelid taxa published in about 630 papers. The majority of these are polychaetes (921 new species and 40 new genera) followed by oligochaetes (308 new species and 10 new genera) and leeches (21 new species). The numerous papers dealing with new polychaete species have provided us a clear picture on which polychaete families have had the most taxonomic effort and which authors and countries have been the most prolific of descriptions of new taxa. An estimated additional 10,000+ species remain to be described in the phylum, thus we urge annelid workers to continue their efforts and aid in training a new generation of taxonomists focused on this ecologically important group.

Ten new species of Phyllodoce Lamarck, 1818 (Phyllodocidae, Annelida) from Brazil.

Herein we provide a taxonomic revision of Phyllodoce species from Brazil, describing 10 new species in addition to two new records, Phyllodoce longipes Kinberg, 1866 and Phyllodoce cf. madeirensis Langerhans, 1880. Phyllodoce sp. A. and Phyllodoce sp. B. are probably new but the number and condition of available specimens do not provide adequate and reliable diagnostic features for a formal description. These species have been collected in diverse marine and estuarine environments from shallow estuarine bottoms to continental shelf and slope sediments and submarine canyons from off southern and southeastern Brazil. A key to the fourteen species of Phyllodoce occurring in Brazil is also given.

An abundant new genus and species of fan worms (Polychaeta: Sabellidae) from Hawaii.

A new genus and species of Hawaiian sabellid polychaete, Euchonoides moeone n. gen. et n. sp. is described. This new species has consistently been one of the most abundant polychaetes collected in Mamala Bay, Hawaii, reaching densities of 141,046 ind. m-2 and representing up to 30.6% of all polychaetes collected in that region. The species has a small body (~2 mm length) with a reduced number of abdominal chaetigers (8-10), and is distinguished by the presence of the following features: 1) three pairs of radioles; 2) radiolar skeleton with two longitudinal rows of cells from radiole base to third proximal pair of pinnules, remainder of each radiole skeleton with single rows of cells; 3) pinnules unpaired, alternating (snowflake arrangement); 4) thoracic uncini acicular with a large tooth above the main fang followed by a series of small ones; 5) thoracic chaetiger 3 enlarged; 6) a wide belt on third abdominal chaetiger; and 7) a pre-pygidial depression composed of three chaetigers, with lateral wings, among a combination of several others features. Histological sections have shown that the abdominal belt seems to be a clitellum-like structure where oogenesis takes place. The new genus is compared with other plesiomorphic genera sharing similar morphological features. Patterns of abundance of the new species are presented for the past 27 years in Mamala Bay.

Two new species of Protocirrineris (Polychaeta: Cirratulidae) from Brazil

Introduction: Brazil has more than 8 000 km of coastline but its marine invertebrates are still poorly known. The cirratulid polychaetes have been an especially neglected group because of its challenging taxonomy. Objective: To describe a new species of Protocirrineris. Methods: In a recent survey in two of the largest Brazilian bays, Todos os Santos Bay and Camamu Bay, 84 specimens of four morphotypes of the multitentaculate genus Protocirrineris were collected. Because of the lack of modified chaetae, the taxonomy of Protocirrineris is challenging and only two of these morphotypes are herein described as new species. Results: These two new species are characterized by having tentacular filaments in two groups over chaetigers 3-4 and first branchiae present from chaetiger 1. They differ from each other in relation to the nature of the achaetigerous region, posterior region, ultrastructure of capillary chaetae and methyl green staining pattern. Two incomplete specimens are also considered as Protocirrineris, and brief descriptions are given. Conclusions: The genus Protocirrineris is cited for the first time in Brazil. Four new morphotypes were found in two large estuaries of Brazil, and two new species are formally described.

Introducción: Brasil tiene más de 8000 km de costa, pero sus invertebrados marinos aún son poco conocidos. Los poliquetos cirratulidos han sido un grupo especialmente descuidado debido a su desafiante taxonomía. Objetivos: Identificar morfotipos de Cirratulidae multitentaculados y encontrar nuevos caracteres diagnósticos. Métodos: En muestreo reciente en dos de las bahías más grandes de Brasil, Bahía de Todos los Santos y Bahía de Camamu, se colectaron cuatro morfotipos del género multitentaculado Protocirrineris. Resultados: Debido a la falta de quetas modificada, la taxonomía de Protocirrineris es un desafío y solo dos de estos morfotipos se describen aquí como nuevas especies. Estas dos nuevas especies se caracterizan por tener filamentos tentaculares en dos grupos sobre los quetígeros 3-4 y las primeras branquias presentes de quetígero 1. Se diferencian entre sí en relación con la naturaleza de la región sin quetas, región posterior, ultraestructura de las quetas capilares y el patrón de tinción con verde de metilo. Dos especímenes incompletos también se consideran Protocirrineris, y se dan breves descripciones. Conclusiones: Se cita por primera vez la presencia del género Protocirrineris en Brasil. Cuatro morfotipos del género han sido encontrados en dos grandes estuarios de Brasil. Dos especies nuevas para la ciencia son descriptas.

Opheliidae (Annelida: Polychaeta) from the western Pacific islands, including five new species.

Intertidal, shallow subtidal and deep-water opheliids from the Hawaiian Islands, Guam in the Mariana Islands and Tutuila in American Samoa were examined and nine species are described, five of which are new. Armandia garretti sp. nov. and A. circumpapillata sp. nov. are new species proposed for previous records of A. intermedia Fauvel, 1902 from Hawaii. Armandia cf. paraintermedia Parapar Moreira, 2015 is recorded from intertidal muddy bottoms of Tutuila and A. amakusaesis Saito, Tamaki Imajima, 2000 from subtidal regions in Guam. Polyophthalmus mauliola sp. nov. is described from Hawaiian material and a comparative table with relevant morphological features of eight species of this genus is presented. Ophelina cf. chaetifera (Hartman, 1965) and Ophelina abranchiata Stop-Bowitz, 1948 are new records to Hawaii from up to 507 m depth, Ophelina kohni sp. nov. is described from shallow waters of Guam and Ophelina manana sp. nov. is described from Mamala Bay, Oahu.

Four new species of Magelona (Annelida: Magelonidae) from Easter Island, Guam and Hawaii.

Several collections of magelonids from Easter Island, Guam in the Mariana Islands and Hawaii were examined. Five magelonids are fully described and illustrated: Magelona anuheone sp. nov. (Easter Island), M. cf. symmetrica Mortimer Mackie, 2006 (Guam), M. alexandrae sp. nov. (Hawaii), M. cinthyae sp. nov. (Hawaii) and M. paulolanai sp. nov. (Hawaii and Guam). Magelona anuheone sp. nov. has a distinctly longer than wide prostomium with inflated and well-developed prostomial horns, similar to M. montera from the Indian Ocean. Magelona alexandrae sp. nov. belongs to Magelona species with crenulated upper margin of thoracic postchaetal lamellae and also well-developed prostomial horns. Magelona cinthyae sp. nov. is unique among its congeners in that several collected adult individuals presented two or more eyespots in the prostomium, a feature only previously recorded to pelagic larval stages. Magelona paulolanai sp. nov. belongs to a group of species with rudimentary prostomial horns, simple capillaries on chaetiger 9 and tridentate abdominal hooks. All species are illustrated and compared to their morphologically similar congeners.

A new species of Raricirrus (Annelida: Cirratuliformia) from deep-water sunken wood off California.

The genus Raricirrus is characterized by the absence of feeding palps, presence of filamentous branchiae, posterior segments shorter and wider than preceding ones, and by having diverse types of chaetae, including serrate capillaries, long natatory capillaries, falcate and finely pectinate, coarsely serrate chaetae and simple curved spines. A new species of Raricirrus is proposed based on morphological and mitochondrial DNA data. The K2P distance comparison of 16S and COI sequences from Raricirrus specimens collected from sunken wood in the deep-sea (3100 m) off Monterey, California, differed in less than 0.02 in both loci from those of another undescribed Raricirrus species collected at deep-sea hydrothermal vents in the East Scotia Ridge, Southern Ocean, and they are considered conspecific. This species is unique among its congeners by the lack of serrate chaetae, presence of acicular spines and neuropodial capillaries. Raricirrus jennae sp. nov. has only long capillaries on anterior notopodia, straight acicular spines with companion capillaries on posterior notopodia (from chaetigers 15-20), and similar acicular spines and companion capillaries throughout neuropodia. Raricirrus jennae sp. nov. appears to be an opportunistic and widely distributed species. The genus Raricirrus is emended to include the presence of acicular spines and keys to all cirratulid and ctenodrilid genera and Raricirrus species are presented.

Taxonomic remarks on the genus Ctenodrilus (Annelida: Cirratulidae) including description of a new species from the Pacific Ocean.

A new species of Ctenodrilus is described based on morphology, anatomy and molecular (COI and 16S) data. Phylogenetic analyses revealed that the newly described Hawaiian species is the sister taxon of the widely distributed C. serratus. Comparisons of K2P distances show distances of at least 10.9 % for 16S and 18.7 % for CO1. Morphology of C. serratus differs from C. pacificus sp. nov. in the shape, number and distribution of multidentate hooks along the body, extent in segments of anterior ventral cilia, and presence of stomach cilia. Ctenodrilus pacificus sp. nov. resembles C. parvulus in terms of the internal anatomy but differs in respect to the shape of multidentate hooks. Asexual reproduction in the new species is described including associated changes in the external morphology and internal anatomy. A revision of the taxonomic characters of Ctenodrilus is also presented in order to provide background information for a better assessment of the widely distributed taxon Ctenodrilus serratus.

Laubieriopsis petersenae n. sp. and L. cf. cabiochi (Amoureux, 1982) (Polychaeta: Fauveliopsidae) from dredge disposal sites off Honolulu, Hawaii.

Fauveliopsid polychaetes have been collected at dredge disposal sites off Honolulu from 397-507 m depth. We report and describe the first Pacific record of Laubieriopsis cf. cabiochi (Amoureux, 1982), originally described from the North Atlantic. A new species, Laubieriopsis petersenae, n. sp. is described as being the species in the genus with the lowest number of body segments (15). Other distinctive features are the presence of bidentate aciculars on thoracic chaetigers, and unpaired genital papilla present on the right side of chaetiger 6/7. The new species is most similar to the L. brevis complex from the Atlantic and L. hartmanae and L. brevis japonica from the Pacific Ocean, but differs on the combination of the characters cited above. We provide an emended diagnosis for this genus to include the ultrastructure of the acicular with rows of spines, and a key to all described species.

The multitentaculate Cirratulidae of the genera Cirriformia and Timarete (Annelida: Polychaeta) from shallow waters of Brazil.

A large number multitentaculate cirratulids have been described worldwide but most are only known through the original descriptions. Type material, voucher and recently collected specimens from Brazil were revisited in order to reveal their true identity and confirm the records of widely distributed species in this region. Six species are described, three of which are new, Cirriformia capixabensis sp. nov., Cirriformia chicoi sp. nov. and Timarete ceciliae sp. nov. COI and 16S sequences were obtained and used for inter-specific comparisons. Timarete caribous is reported from several localities along the Brazilian coast and a new synonym, Cirratulus melanacanthus, is proposed. The species Timarete oculata, originally described from Brazil and lumped into the Timarete filigera species complex, is herein revalidated and redescribed. The occurrence of the species Timarete filigera and Cirriformia tentaculata is not confirmed from the Brazilian coast. Descriptions, illustrations and a key to genera and species are provided.

Bitentaculate Cirratulidae (Annelida: Polychaeta) from the northwestern Pacific Islands with description of nine new species.

Thirteen cirratulid species from the Hawaiian, Mariana and Marshall Islands are described. Nine species are new to science: Aphelochaeta arizonae sp. nov., Aphelochaeta honouliuli sp. nov., Caulleriella cordiformia sp. nov., Chaetozone michellae sp. nov., Chaetozone ronaldi sp. nov., Monticellina anterobranchiata sp. nov., Monticellina hanaumaensis sp. nov., and Tharyx tumulosa sp. nov., from Oahu, Hawaii and Aphelochaeta saipanensis sp. nov., from Saipan in the Mariana Islands. Dodecaceria fewkesi and Monticellina nr. cryptica are newly recorded from the Hawaiian Islands. Dodecaceria laddi is widely distributed in the western Pacific and material collected from the Hawaiian, Mariana and Marshall islands is described. We provide SEM photographs for all species in addition to line drawings and methyl green staining pattern photographs for the new species.

Integrated assessment of mangrove sediments in the Camamu Bay (Bahia, Brazil).

Camamu Bay, an Environmentally Protected Area, may be affected by the pressures of tourism and oil exploration in the adjacent continental platform. The current quality of the mangrove sediments was evaluated by porewater bioassays using embryos of Crassostrea rhizophorae and by an analysis of benthic macrofauna and its relationships with organic compounds, trace metals and bioavailability. Porewater toxicity varied from low to moderate in the majority of the samples, and polychaetes dominated the benthos. The Grande Island sampling station (Station 1) presented more sandy sediments, differentiated macrobenthic assemblages and the highest metal concentrations in relation to other stations and guideline values, and it was the only station that indicated a possible bioavailability of metals. The origin of the metals (mainly barium) is most likely associated with the barite ore deposits located in the Grande and Pequena islands. These results may be useful for future assessment of the impact of oil exploration in the coastal region.

Relationship of metal content and bioavailability with benthic macrofauna in Camamu Bay (Bahia, Brazil).

Camamu Bay (Bahia, Brazil) is an Environmental Protected Area with mangroves of economic and ecological importance. The objective of this study was to elucidate, through the distribution of the benthic macrofauna and its relationships with trace metals and bioavailabilty, if the current quality of the mangrove sediments of Camamu Bay is acceptable for the protection of aquatic life. Seven sampling stations were selected as representative of the meso-littoral region of Camamu Bay. It was found 581 macrobenthic organisms distributed in 38 species. The highest values of metals occurred at stations located in areas that influenced by barite extraction, while the lowest concentrations were found in areas with relatively lower anthropogenic influence. Analysis of acid volatile sulphide and simultaneously extracted metals showed the occurrence of the ratio SEM/AVS >1, indicative of possible bioavailability of metals, at only one station. The results suggested that Camamu Bay is a nearly pristine area.