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Polychaetes of the spionid genus Trochochaeta occur mainly in the northern hemisphere, including North and Central America. In South America, they have been reported only from the northeast region of Brazil – Sergipe and Paraíba – despite numerous biological investigations around the continent. In 2006, a dense population (up to 7000 individuals per square meter) of Trochochaeta was discovered in the estuary of Santos, São Paulo, Brazil, hosting the busiest container sea port in Latin America, and in 2008, one Trochochaeta specimen was found in Camamu Bay, Bahia. We identify these worms as Trochochaeta japonica Imajima, 1989 and describe and illustrate their morphology. This is the first record of the species from outside of its type locality in Honshu, Japan. It might have been introduced to the estuary of Santos as larvae in ballast water of ocean-going vessels. We review the systematics of Trochochaeta and provide an identification key to 12 currently recognized species.

Trochochaeta japonica Imajima, 1989 (Figs 2���6) Trochochaeta Japonica Imajima, 1989: 139 ���145, figs 2���5. Material. BRAZIL, S��o Paulo, Ba��a de Santos, coll. S. Sartor: st. 5, 23.986547��S, 46.288919��W, 14.8 m, 0 9 Oct 2006, UERJ 364 (1); st. 12, 23.925733��S, 46.323285��W, 15.8 m, 11 Oct 2006, UERJ 19 (1), MNRJ P1463 (3 sPecimens mounted on SEM stubs); st. 21, 23.913450��S, 46.374767��W, 6 m, 8 Oct 2006, MNRJ P1462 (2 sPecimens mounted on SEM stubs), 10 Oct 2006, UERJ 63 (46), NHMUK 2017.216���225 (15), MIMB 33633 (19), SMF 24358 (15); st. 24, 23.914689��S, 46.310389��W, 2.6 m, 11 Oct 2006, UERJ 121 (2); st. 25, 23.920325��S, 46.305252��W, 4.1 m, 11 Oct 2006, UERJ 49 (45); st. 26, 23.919175��S, 46.293536��W, 3.2 m, 11 Oct 2006, MNRJ P1459 (1), UERJ 19 (16); st. 28, 23.916811��S, 46.277 314��W, 6 m, 11 Oct 2006, UERJ 172 (51), MNRJ P1461 (2); st. 35, 23.923031��S, 46.401797��W, 6.4 m, 0 8 Oct 2006, UERJ 240 (4); st. 40, 23.958794��S, 46.417139��W, 5.5 m, 0 8 Oct 2006, UERJ 281 (1). Bahia, Camamu Bay, Serinha��m Estuary, coll. F. Barros: st. 35, 13.760263��S, 39.070332��W, 8.1 m, 20 SeP 2008, UFBA-LEB 0 0 4 (1). SOUTH KOREA, East China Sea, coll. J.- W. Choi: Hallyeo marine Park, st. 140, 34.7411��N, 128.4367��E, 10 m, 7 May 2014, MIMB 33 635 (1); st. F15, 33.00��N, 127.00��E, 103 m, 1 Jun 2015, MNRJ P1637 (3); st. A3, 34.42��N, 128.50��E, 61 m, 8 Jun 2015, MIMB 3 3636 (1); st. H12, 32.00��N, 126.75��E, 109 m, 7 Nov 2015, MIMB 33637 (2). Adult morphology (based on material from BraZil). All sPecimens anterior fragments, largest about 20 mm long and 2 mm wide for 40 chaetigers. Pigmentation absent on body and PalPs, but glandular Pads above and below neuroPodia from chaetiger 5 to chaetiger 15 (Fig. 2A) and in notoPodial lamellae on chaetigers 5���10 aPPearing rose in fixed sPecimens. Anterior 15 chaetigers widest, flattened dorso-ventrally; succeeding chaetigers gradually narrowing, oval to rounded in cross-section. Prostomium small, fusiform, widest in middle Part, anteriorly rounded to truncate, with four small knobs, comPrising one Pair of fronto-lateral knobs and one Pair of median knobs; Posteriorly extending to end of chaetiger 1 as a narrow caruncle (Figs 3A, 5A). Peristomium reduced to narrow lines on sides of Prostomium, and a narrow ventral liP enclosing mouth laterally and Posteriorly (Fig. 5B). Two Pairs of small red eyes arranged traPeZoidally, comPrising one Pair of median eyes deePly imbedded into Prostomium and not seen in some sPecimens, and one Pair of lateral eyes situated anteriorly and set wider aPart; in each Pair eyes often situated asymmetrically (Fig. 5A). Short occiPital antenna Present on Prostomium behind median eyes; antenna low, indistinct and broken in some sPecimens. Nuchal organs U-shaPed ciliary bands on sides of caruncle (Figs 3A, 5A). PalPs arising from dorsal Parts (residues) of Peristomium, between Prostomium and notoPodia of first chaetiger, as long as 20���30 chaetigers, with frontal longitudinal groove lined with fine cilia and sided by undulating membrane. Chaetiger 1 with short smooth straight caPillaries in notoPodia and long smooth caPillaries in neuroPodia; neurochaetae about twice as long as notochaetae, arranged in a fan and directed antero-laterally and uPwards (Fig. 5A). Postchaetal lamellae fleshy and conical in both rami; notoPodial lamellae twice as long as neuroPodial lamellae (Figs 3B, 5A). Middorsal Part of chaetiger 1 extending Posteriorly and Pressed into chaetiger 2, thus caruncle aPPearing very close to Posterior edge of chaetiger 2 (Fig. 3A). Chaetiger 2 with neurochaetae and fleshy conical lamellae in both rami, notochaetae absent (Figs 3B, C, 5A). NotoPodial lamellae situated close to neuroPodial lamellae and both shifted ventrally, aPPearing lower than neuroPodial lamellae on chaetigers 1 and 3. Neurochaetae on each side comPrising uP to seven thin falcate yellowish sPines arranged in a fan-shaPed vertical row and alternating with equal number of simPle hirsute caPillaries arranged between or slightly Posterior to sPines. Chaetiger 3 with smooth simPle caPillaries in notoPodia and two kinds of chaetae in neuroPodia (Figs 3B, C, 5C). Notochaetae on each side arranged in three grouPs comPrising suPerior tuft of 3���4 caPillaries, and anterior and Posterior vertical rows of slightly shorter caPillaries, uP to six in each row. Neurochaetae comPrising uP to six falcate sPines arranged in a fan-shaPed vertical row and alternating with equal number of short and slender hirsute caPillaries situated between sPines or slightly Posterior to them. Falcate sPines dark brown, smooth and heavy, much larger and darker than sPines of chaetiger 2, deePly embedded into body, with distal Part slightly curved and Protruding out of body wall. Postchaetal lamellae short and fleshy, conical, slightly flattened in both rami. Chaetiger 4 with simPle caPillaries and fleshy, oval, flattened Postchaetal lamellae in both rami (Figs 3B, D, E, 5D). Chaetae in each ramus arranged in three grouPs, in notoPodia comPrising suPerior tuft of 3���5 long and slightly hirsute caPillaries, and anterior and Posterior vertical rows of short and consPicuously hirsute caPillaries, and in neuroPodia comPrising anterior and Posterior vertical rows of hirsute caPillaries and inferior tuft of 2���4 slightly shorter and thinner hirsute caPillaries (Fig. 3D, E). From chaetiger 5, notoPodial caPillaries gradually reduced in number and Postchaetal lamellae gradually reduced in siZe (Fig. 2A); both caPillaries and lamellae absent after chaetiger 10, excePt small lamellae Present on chaetiger 11 in some individuals. NeuroPodia of chaetigers 5���15 large, with numerous chaetae Protruding from Prominent conical neuroPodial lobes flanked Posteriorly by fleshy, rounded, flattened Postchaetal lamellae (Fig. 3B, D). Lower Parts of neuroPodial lobes greatly inflated, largest on chaetigers 7���10, with numerous glandular ePithelial cells gathered in distinct Patches or Prominent Pads (Fig. 2A), aPPearing rosy in fixed sPecimens; same rosy glandular cells also Present in antero-dorsal Parts of neuroPodia and in notoPodial Postchaetal lamellae on same chaetigers. Neurochaetae of chaetigers 5���15 comPrising two vertical rows of frayed, flattened, distally Pointed heavy sPines (Figs 3D, 6A), uP to nine sPines in each row, Posterior row of uP to 18 long caPillaries with consPicuously hirsute convex side of distal end (Figs 3D, 6B), and inferior tuft of 2���5 slightly shorter and thinner caPillaries (Fig. 6C). NeuroPodial sPines heaviest and darkest on chaetigers 6���10, gradually becoming smaller, thinner, lighter and fewer on succeeding chaetigers. From chaetiger 16 onwards, neuroPodia small, with three kinds of chaetae Protruding from low conical neuroPodial lobes flanked by small triangular Postchaetal lamellae and extending Posteriorly as thin horiZontal membranes (Fig. 6H); notoPodia lacking. Neurochaetae comPrising anterior tuft of 2���5 long caPillaries weakly hirsute on distal convex side (Fig. 6G), 2���5 aristate sPines arranged in almost horiZontal row and alternating with similar number of smooth syringe-like sPines (Figs 3F, 4A, 6 D���F). Distal ends of aristate sPines curved and flattened, greatly Protruding out of neuroPodial lobe, each having hirsute convex side and a long Pointed terminal Process (Fig. 6D, E). Syringe-like sPines mostly embedded into neuroPodial lobes and only long Pointed distal ends Protruding outside (Figs 3F, 4A, 6F). One Pair of small PaPillae Present on ventral side of each chaetiger from chaetigers 13���15 to chaetigers 19���22 (Fig. 4B). From chaetigers 37���41 onwards, each notoPodium with a bundle of uP to seven straight acicular sPines (Fig. 2B). SPines entirely embedded into body wall; notoPodial lobes and Postchaetal lamellae lacking. Small mouth flanked Posteriorly by ventral Peristomial liP (Fig. 5B). Foregut axial, with two small, aPParently ciliated, dorso-lateral folds. Ventral buccal bulb absent. Narrow oesoPhagus extending throughout thoracic chaetigers and terminating with simPle voluminous, thin-walled giZZard-like structure beginning from chaetigers 15���17 and extending through 3���6 chaetigers. Main dorsal blood vessel without heart body. NePhridia well seen from chaetiger 16 onwards, not certain in more anterior chaetigers. Juvenile morphology. Smallest sPecimen about 0.3 mm wide with notoPodial caPillaries of chaetigers 1���10 (excePt chaetiger 2) and neuroPodia of chaetigers 1���4 aPPearing same as in larger sPecimens. NeuroPodia of chaetigers 5���10 with frayed sPines arranged in two vertical rows, caPillaries arranged in a Posterior row, and large glandular Pads. From chaetigers 9���10 Posteriorly, frayed sPines gradually becoming thinner, straighter and lighter, and on chaetigers 11���12 aPPearing similar to caPillaries. From chaetiger 13 onwards, neuroPodia with 1���2 slender caPillaries, 1���2 aristate sPines, 1���2 syringe-like sPines, small conical Postchaetal lamellae and lateral membranes. SPecimens about 0.7 mm wide with notoPodial caPillaries of chaetigers 1���10 (excePt chaetiger 2) and neuroPodia of chaetigers 1���4 aPPearing same as in larger sPecimens. NeuroPodia of chaetigers 5���12 with frayed heavy sPines arranged in two vertical rows, caPillaries arranged in a Posterior row, and large glandular Pads. From chaetigers 9���10 Posteriorly, frayed sPines gradually becoming thinner, straighter and lighter, and on chaetigers 12��� 13 aPPearing similar to caPillaries. From chaetiger 14 onwards, neuroPodia flat, without glandular Pads, with 1���2 slender caPillaries, 1���2 aristate sPines, 1���2 syringe-like sPines, small conical Postchaetal lamellae and lateral membranes. SPecimens about 0.9 mm wide with large glandular Pads on neuroPodia of chaetigers 5���13. Chaetigers 14 and 15 flat, with small conical or triangular neuroPodial Postchaetal lamellae (lamellae slightly enlarged on chaetiger 14) and lateral membranes; ventral glandular Pads not yet develoPed but glandular cells Present in neuroPodial lamellae of chaetiger 14. Neurochaetae of chaetiger 14 aPPearing as caPillaries; aristate and syringe-like sPines absent. From chaetiger 15 onwards, neurochaetae comPrising 2���3 caPillaries, 1���3 aristate sPines and 1���3 syringelike sPines. Habitat. In the estuary of Santos, S��o Paulo, adults of T. japonica occurred at the dePth of 2.6���15.8 m in sandy and muddy sediments with shell fragments and gravel. The salinity at the stations varied from 17.6 to 27.3���. Density of worms at some stations reached 7000 individuals Per one square meter. All individuals were collected in October 2006 and were immature. In Camamu Bay, Bahia, the only sPecimen was collected in SePtember 2008 from silty sediment at the dePth of 8.1 m, salinity 27.3���; it was immature, aPParently juvenile., Published as part of Radashevsky, Vasily I., Rizzo, Alexandra E. & Peixoto, Antonio J. M., 2018, First record of Trochochaeta japonica (Annelida: Spionidae) in Brazil with identification key to species of the genus, pp. 566-578 in Zootaxa 4462 (4) on pages 568-572, DOI: 10.11646/zootaxa.4462.4.8, http://zenodo.org/record/1441881, {"references":["Imajima, M. (1989) A new species of Trochochaeta (Polychaeta, Trochochaetidae) from Japan. Bulletin of the National Science Museum, Tokyo, Series A (Zoology), 15 (3), 139 - 146."]}

The small, monogeneric family of polychaetes known as Trochochaetidae has been exclusively collected in the northern hemisphere, mainly in temperate–cold environments. Nine species have been described so far including Trochochaeta mexicana sp. nov. described herein, while one species remains unnamed. Only two species had previously been recorded in the eastern Pacific, so T. mexicana sp. nov. is the first record for the family in the tropical Mexican Biogeographic Province. The new species is characterized by having a pair of eyes, acicular neurochaetae on chaetigers 2 and 3, a small knob-like antenna and a nuchal crest projecting through chaetiger 1. Trochochaeta mexicana sp. nov., together with Trochochaeta kirkegaardi, Trochochaeta diverapoda and Trochochaeta cirrifera are the only trochochaetids that have been found exclusively in warm environments.

Trochochaeta Levinsen, 1884 diverapoda (Hoagland, 1920): Taratara, Philippines. USNM (redescr. Pettibone 1976b, Mackie 1990a), Published as part of Salazar-Vallejo, Sergio I., Carrera-Parra, Luis F., Muir, Alexander I., León-González, Jesús Angel De, Piotrowski, Christina & Sato, Masanori, 2014, Polychaete species (Annelida) described from the Philippine and China Seas, pp. 1-68 in Zootaxa 3842 (1) on page 45, DOI: 10.11646/zootaxa.3842.1.1, http://zenodo.org/record/4928482, {"references":["Hoagland, R. A. (1920) Polychaetous annelids collected by the United States Fisheries Steamer \" Albatross \" during the Philippine Expedition of 1907 - 1909. Bulletin of the United States National Museum, 100 (1), 603 - 635. http: // dx. doi. org / 10.5962 / bhl. title. 23987","Pettibone, M. H. (1976 b) Contribution to the polychaete family Trochochaetidae Pettibone. Smithsonian Contributions to Zoology, 230, 1 - 25. http: // dx. doi. org / 10.5479 / si. 00810282.230"]}

Salazar-Vallejo, Sergio I., Carrera-Parra, Luis F., Muir, Alexander I., León-González, Jesús Angel De, Piotrowski, Christina, Sato, Masanori (2014): Polychaete species (Annelida) described from the Philippine and China Seas. Zootaxa 3842 (1): 1-68, DOI: http://dx.doi.org/10.11646/zootaxa.3842.1.1

Family: Trochochaetidae Species: Cherusca nitens Müller 1858 References: Müller (1858) Environment: unknown Depth: unknown Coordinates: unknown Note: Specimens from the type locality are needed to elucidate the taxonomical position of this species. This species seems to be endemic to the studied area.

This study summarizes taxonomic information on polychaetes from Santa Catarina State, southern Brazil, between25º57'S and 29º23'S, and provides species distribution records together with information on habitats, based on historicaldata and novel records from primary surveys. Rarefaction curves showed that most species were found in the shallowsublittoral (to 60 m) rather than in deep sublittoral (>60 m) or estuarine habitats. Altogether, 228 valid species belongingto 141 genera and 44 families were recorded. This inventory adds 141 new records to previous regional reports. We founda shift in occurrence of species when comparing data from the study area with data from both southward (29–33º S) andnorthward (23–26º S) sites. Few species were shared between consecutive sites: this could be a response to the regionalbehaviour of the atmosphere and water masses, with a progressive increase in the influence of subantarctic waters and a decrease in the influence of subtropical waters.

Metacer-cariae, found in the body-cavities of Trochochaeta multisetosa (Oersted) (Trochochaetidae, Polychaeta sedentaria) are described and identified as belonging to Zoogonoides viviparus (Olsson, 1868) Odhner, 1902. A combination of these observations with the Results of investigations, made by previous authors, on the biology of the cercariae, gives the outlines of a life cycle for Z. viviparus.