Posterior Chaetigers Research Articles

Revision ofTrophoniellaHartman, 1959 (Polychaeta, Flabelligeridae)

The identification and classification of flabelligerid polychaetes have been problematic due to three reasons: 1) the anterior end is rarely exposed and it carries the branchiae, whose type and arrangement are diagnostic; 2) there is no standardisation for naming chaetae; and 3) morphological delineations for most genera have been unstable. A redefinition and a revision of the type material of many species originally described in other genera but belonging to Trophoniella Hartman, 1959 are herein presented. Trophoniella together with Piromis Kinberg, 1856 and Pycnoderma Grube, 1877 share a very thick tunic and a projected branchial membrane which resembles a tongue. Their main difference is the type of neurochaetae in median and posterior chaetigers; thus, Trophoniella is redefined and restricted to include only the species with anchylosed hooks, whereas they are multiarticulated in Piromis and oligoarticulated in Pycnoderma; these two latter genera have been revised elsewhere. Therochaetella Hartman, 1967 is being regarded as a junior synonym of Trophoniella. The species of Trophoniella are further separated in two groups by the start of the anchylosed neurohooks (from about the chaetiger 10 or from median or posterior chaetigers). The species within each group can be separated by using the variation in the sediment cover and other attributes of noto- and neurochaetae. The genus as herein redefined contains, besides the type species, T. avicularia Caullery 1944 from Indonesia, 26 species including 11 previously undescribed: T. americana (Monro, 1928) n. comb, from Galapagos and Panama, T. bastidai n. sp. from western Mexico, T. borealis (Hartman, 1965) n. comb, from northeastern South America, T. capitata (Nonato, 1966) n. comb, from Brazil, T. chilensis (Hartman, 1967) n. comb, from Chile, T. ehlersi (Day, 1973) n. comb, from the eastern United States, T. eliasi n. sp. from central Argentina, T. enigmatica n. sp. from the Mediterranean Sea, T. fauveli n. sp. from the Mediterranean Egyptian coast, T. fernandensis (Augener, 1918) reinstated, n. comb, from northwestern Africa, T. fiegei n. sp. from the Persian Gulf, T. grandis (Blanchard in Gay, 1849) n. comb, from central Chile, T. harrisae n. sp. from southern California, T. havaica (Kinberg, 1867) n. comb, from Hawaii, T. hospita (Fauchald, 1972) n. comb, from the Gulf of California, T. incerta (Augener, 1918) n. comb, from West Africa, T. indica (Fauvel, 1928) n. comb. from the Bay of Bengal, T. jareckiorum n. sp. from the Caribbean Sea, T. lindae n. sp. from the Caribbean Sea, T. minuta (Blanchard in Gay, 1849) n. comb. from Chile, T. orensanzi n. sp. from Uruguay, T. reishi n. sp. from the Gulf of California, T. rigida (Caullery, 1944) n. comb. from Indonesia, T. rudis (Grube & Muller in Grube, 1877) n. comb. from southern Brazil, T. salazarae n. sp. from western Mexico, and T. tumbensis (Hartmann-Schroder, 1962) n. comb. from Chile. Members of the species are marine and mainly tropical or subtropical, thriving in shallow bottoms.

Morphological and molecular sequence analysis of the harmful shell boring species of Polydora (Polychaeta: Spionidae) from Japan and Australia

Accurate species identification is required to trace, monitor and limit the distribution of harmful shell boring species of the genus Polydora, which have been transported worldwide accompanying commercially important mollusk species. Morphological identification of species in the polydorid complex is difficult because of close similarities, therefore, nuclear 18S rRNA gene sequences were used for the first time to distinguish among the three serious aquaculture pests Polydora brevipalpa, Polydora uncinata, and Polydora aura, from Japan and Australia. The analysis revealed new intraspecific pigmentation variation and confirmed that P. uncinata and P. aura are closely related, possessing special notochaetae on the posterior chaetigers, while P. brevipalpa is a sister taxon to these two species. Polydora brevipalpa and P. uncinata share characteristic black-bar pigmentation on their palps, but they apparently are not part of the same clade.

A new species of Acrocirrus (Polychaeta: Acrocirridae) from Coconut Island, Oahu, Hawaii

A new species of Acrocirrus is described from shallow waters of Coconut Island in Kaneohe Bay, Oahu, Hawaii. Acrocirrus bansei sp. nov. is an Acrocirrus whose segment 13 (chaetiger 11) is modified and equipped with a heavy neuropodial acicular hook. This new species is most similar to A. frontifilis based on the presence of notopodial cirri, which have been, up to now, a unique feature of A. frontifilis. The species differ most notably by the absence of the notopodial cirri on the posterior chaetigers. A key to all recognized species of Acrocirrus is presented.

Revision of Piromis Kinberg, 1867 and Pycnoderma Grube, 1877 (Polychaeta: Flabelligeridae)

The taxonomy of flabelligerid polychaetes has been difficult because of three main problems: 1) the eversible anterior end is rarely exposed and its appendices are poorly known, 2) there is no standard terminology for chaetae, and 3) most generic definitions have been unstable or improperly defined. A redefinition and revision of all species in Piromis Kinberg, 1867 and Pycnoderma Grube, 1877 is herein presented. Piromis, Pycnoderma, and Trophoniella Caullery, 1944 share a thick tunic and a projected, tongue-shaped branchial plate. Their main difference is the type of neurochaetae in median and posterior chaetigers; thus, Piromis has multiarticulate, often bidentate neurochaetae, whereas Pycnoderma has oligoarticulate, often mucronate neurochaetae, while Trophoniella has anchylosed neurochaetae. This latter genus is being revised elsewhere. The species in Piromis or Trophoniella are separated depending on the extent and type of sediment cover, together with the presence of notopodial or dorsal lobes, the relative length of chaetal articles, especially in neurochaetae, and the relative abundance of body papillae or cephalic cage chaetae. As herein defined, Piromis includes 12 species with five being newly described, while Pycnoderma includes eight species with three being newly described. The species in Piromis are P. arenosus Kinberg, 1867 (type species), P. amoureuxi n. sp. from the Lesser Antilles, P. brisegnoi n. sp. from the Gulf of California, P. capulata (Moore, 1909) n. comb., P. eruca (Claparède, 1869), P. fauchaldi n. sp. from the Gulf of California, P. kisemboanus (Augener, 1918) n. comb., P. robertsi (Hartman, 1951), P. suni n. sp. from the South China Sea, P. vossae n. sp. from the Strait of Florida, P. websteri Day, 1973 n. status, and P. wehei n. sp. from the Indian Ocean. On the other hand, the species in Pycnoderma are P. congoense Grube, 1877 (type species), P. dannyi n. sp. from tropical Western Africa, P. escobarae n. sp. from the Gulf of Mexico, P. ferruginea (Gallardo, 1968) n. comb., P. glabra (Treadwell, 1901) n. comb., P. glasbyi n. sp. from Northeastern Australia, P. gracilis (Hartman, 1961) n. comb., and P. talehsapensis (Fauvel, 1932) n. comb. Another species, P. fernandense Augener, 1918, described from two localities from Ghana and Equatorial Guinea, is transferred to Trophoniella Caullery, 1944, by having anchylosed neurospines in posterior chaetigers. All Piromis and Pycnoderma species thrive in sediments, sometimes in mixed environments, in tropical to temperate regions. Piromis includes mostly shallow water species while Pycnoderma includes species living in greater depths.

Pseudopolydora species associated with mollusc shells on the south coast of South Africa, with the description of Ps. dayii, sp nov.

Two species of the genus Pseudopolydora, Ps. dayii, sp. nov. and Ps. antennata, were associated with gastropods on the south and south-east coasts of South Africa. Pseudopolydora dayii is characterized by prominent post-chaetal notopodial lobes on chaetiger 1 with very long chaetae, a prominent occipital tentacle, having hooded hooks that start on chaetiger 9, branchiae that start on chaetiger 6, stout hooks and lobes placed latero-posteriorly to the hooded hooks in posterior chaetigers. It is a surface-fouler and was found on several species of wild gastropods at four of the five sites sampled and from additional material from the south-west coast and on cultured abalone (Haliotis midae) at a farm on the south-west coast. Three individuals of Ps. antennata were found only with oysters at the easternmost site. This was the first record of this species outside of the Western Cape Province and it is possible that their association with the oysters was fortuitous.

Morphology and biology of a new Rhynchospio species (Annelida: Spionidae) from the South China Sea, Vietnam, with the review of Rhynchospio taxa

Adults of a new spionid polychaete, Rhynchospio nhatrangi, inhabit sandy tubes on muddy sand intertidal flats in an estuary of Nha Trang Bay, southern Vietnam. The worms are up to 8 mm long and 0.5 mm wide for 55 chaetigers. They are unique among spionids in the changes in the arrangement of hooks during ontogenesis: first development of tridentate hooks in neuropodia from chaetiger 10, later loss of hooks in chaetiger 10, and replacement of tridentate hooks by heavy unidentate hooks in neuropodia of chaetigers 11–14. Adults are simultaneous hermaphrodites having sperm in chaetigers 11–14 and oocytes from chaetiger 15 to 23–33. Spermatozoa are introsperm, about 300 µm long. Oocytes are about 120 µm in diameter, with a thin and smooth envelope. Fertilization and early larval development occur in a hatchery formed by elongated dorsal capillaries on the posterior chaetigers. Larvae escape from the hatchery probably when they have developed four chaetigers and then continue development in seawater, feeding on the plankton. When larvae have grown to 14–15 chaetigers, they likely undergo gradual metamorphosis and settle on the bottom. Metameric nuchal organs, glandular pouches in neuropodia, metanephridial segmental organs, hermaphroditism, sperm, and early larval morphology are described here for the first time for Rhynchospio species. An identification key is provided to eight currently recognized Rhynchospio species.

Significance of chaetal arrangement for maldanid systematics (Annelida, Maldanidae)

Maldanids are usually divided into several subfamilies: Euclymeninae, Lumbriclymeninae, Maldaninae, Nicomachinae, Rhodininae, Clymenurinae, Notoproctinae, and Boguinae. The taxonomy of maldanids and the delimination of these taxa are mainly based on head morphology, total number of segments, chaetal structure, shape of the pygidium, and position of the anus. The maldanid ingroup relationships, as well as the monophyly of the proposed subfamilies, have so far not been investigated. Pilgrim (1977) described a shift of the notopodial chaetal rows from a transverse direction in anterior chaetigers to a more longitudinal one in posterior chaetigers in Clymene torquata (Leidy, 1855) and Euclymene oerstedii (Claparede, 1863), both belonging to the Euclymeninae. We investigated several maldanid species to assess the usefulness of this character for maldanid systematics and used 3D-reconstruction techniques to reveal the complete geometry of the chaetal sacs. Our investigation shows that a shift is apparent in Euclymene, Axiothella, Johnstonia (all Euclymeninae) and Clymenura (Clymenurinae), but absent in species like Maldane sarsi (Malmgren, 1865), Metasychis disparidentata (Moore, 1904) (both Maldaninae) and Petaloproctus borealis Ardwisson, 1906 (Nicomachinae). The shift is not typical for sedentary polychaetes and is apomorphic within maldanid polychaetes. It thus argues for a close relationship between Euclymeninae and Clymenurinae. The investigation of further maldanid species of different subfamilies may shed additional light on maldanid systematics.