Generic interrelationships within the Spionidae (Annelida: Polychaeta)

The phylogenetic relationships of spionid genera are estimated from parsimony analyses of morphological characters, with Trochochaetidae, Poecilochaetidae and Uncispionidae as outgroups. A first analysis of currendy recognised genera proved inconclusive and even exclusion of six of the most polymorphic genera resulted in 13 305 equally parsimonious trees and a fully collapsed consensus tree. A second analysis using only the type species of each genus, yielded four equally parsimonious trees; reduced to two after successive weighting. The topologies of these two trees indicated division of the family into four main groups: (1) Aonidella and Xandaros; (2) Prionospio (sensu fato)-complex, Laonice, Spiophanes and Aonides; (3) a large assemblage of genera, including Polydora-{senm late), Scolelepis, Malacoceros and Spio; (4) Atherospio, Pseudatherospio and Pygospiopsis. Earlier literature classifications of the group are evaluated and compared with die new results.     

A new genus of Syllidae (Polychaeta) from Western Australia

During a study carried out on the subfamily Exogoninae (Syllidae) from Australia, several specimens of a new genus and species were found in samples of dead coral substrate from Western Australia. They have long palps, fused except for a terminal notch, long median and two short lateral antennae, a single pair of short tentacular cirri, and short dorsal cirri, somewhat longer than the parapodial lobes. These characters resemble those of the genus Exogone Örsted, 1845. However, all these appendages are articulated. The chaetae are very similar to those of several species of Syllis Lamarck, 1818, having coarse spines on the margin of compound chaetal blades and truncated dorsal simple chaetae. Furthermore, the pharynx begins in chaetiger 3, posterior to the peristomium, as in many species of the genus Syllis; this condition does not occur in any described species of Exogone. The new genus is provisionally proposed to belong to the subfamily Syllinae, although it has some characters typical of the Exogoninae. Examination under the SEM shows another peculiar feature, the nuchal organs are distinctly laterally located. Within the Syllinae, only Paratyposyllis Hartmann-Schröder, 1962 has a single pair of tentacular cirri, but in that genus, the palps are only basally fused.     

Syllidae (Annelida, Polychaeta) from the Caribbean coast of Venezuela

Venezuela possesses a great variety of coastal environments allowing for a high diversity of marine species. However, systematic studies on marine invertebrates are scarce, especially on polychaetes. The family Syllidae is poorly known, and only 14 genera and 42 species have been reported from this country. A total of 13 genera and 26 species the Syllidae were identified from benthic samples collected on different substrata of the northeastern coast of Venezuela. Of these, seven genera and 16 species constitute new records for Venezuela: Odontosyllis guillermoi, Syllides floridanus, Salvatoria clavata, Salvatoria limbata, Sphaerosyllis longicauda, Parapionosyllis longicirrata, Trypanosyllis parvidentata, Trypanosyllis vittigera, Opisthosyllis sp., Syllis amica, Syllis armillaris, Syllis gracilis, Syllis pseudoarmillaris, Syllis vittata, Parasphaerosyllis indica and Myrianida convoluta.     

Phylogeny of Syllidae (Polychaeta) based on morphological data

The phylogeny of Syllidae is assessed in two parsimony analyses of 107 morphological characters. The first analysis included one species of each of the 71 genera of the Syllidae, as well as members of other close families. In the second analysis, 23 poorly known genera were excluded. Character information is based on the examination of available types, additional non-types and newly collected material. Syllidae, except Bollandia Glasby, 1994 is monophyletic. Both analyses supported three of the four traditional subfamilies (Exogoninae, Syllinae and Autolytinae) as monophyletic, whereas Eusyllinae was clearly a polyphyletic group. The genera Anoplosyllis Claparède, 1868, Astreptosyllis Kudenov & Dorsey, 1982 , Streptosyllis Webster & Benedict, 1884, Streptospinigera Kudenov, 1983 and Syllides Örsted, 1845 comprise a well-supported monophyletic group, which we classified as a new subfamily: Anoplosyllinae n. subfam. Our results indicated high levels of homoplasy in the morphological characteristics that traditionally used to differentiate groups, such as the fusion of palps and the presence of nuchal epaulettes. Considering the reproductive modes, schizogamy has appeared twice in the family as the derived condition evolving from epigamy, and Exogoninae may be divided into two monophyletic groups based on the brood system.     

On the associations between Haplosyllis (Polychaeta, Syllidae) and gorgonians (Cnidaria, Octocorallaria), with the description of a new species

The present paper includes a morphological, ecological and biological updating of the three gorgonian associated species of Haplosyllis (Polychaeta, Syllidae) known to date: H. chamaeleon (symbiont with Paramuricea clavata in the Mediterranean), H. anthogorgicola (symbiont with Anthogorgia bocki in the Japanese seas) and H. villogorgicola , a new species living symbiotically with Villogorgia bebrycoides which is only known from Tenerife (Canary Islands, Eastern Central Atlantic). The new species is described on the basis of ecological, morphological, morphometric and statistical analysis of relevant characteristics. Each host colony harboured about 15 pale-yellowish worms, whose cryptic colouration mimicked that of the host. They occurred either on the host branches or partly hidden inside cavities formed by the fusion of two branches. The new species is characterized by the presence of simple chaetae with clearly bidentate tips all along the body, the presence of gland pore aggregates distributed in two lateral rows and two ventral patches on each palp and the absence of ciliary tufts on the pharyngeal papillae. H. villogorgicola sp. nov. is closely related to H. chamaeleon . Thus, it is compared with two populations of this species collected in the north-west and south-west Mediterranean. Stolons of H. chamaeleon are re-described as tetracerous and a peculiar posterior end regeneration process occurring in adult worms during the stolon formation is described. H. anthogorgicola is also re-described, with particular emphasis on its appendage and chaetal arrangements. The main features of the three associations are discussed in light of the current knowledge on symbiotic polychaetes, particularly cnidarian-associated syllids.  © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 77 , 455–477.     

Endocrine control of reproductive periodicity in male Typosyllis prolifera (Polychaeta,Syllidae)

Under a “summer” light-temperature regime (LD 16:8, 20°C), the polychaete Typosyllis prolifera shows a spontaneous 30-day cycle of reproduction (stolonization). Previous experiments suggested cyclic reproduction to be controlled by corresponding changes in the inhibitory endocrine activity of the proventriculus. The evidence in this paper, however, indicates that the prostomium rather than the proventriculus is the primary source of control of reproductive periodicity. The prostomium of a “summer” male undergoes a spontaneous lunar cycle of hormonal activity. Hormone secretion occurs around day 13 after previous stolon release each time. The hormone probably operates a triggering mechanism that shifts worms from the postreproductive regeneration phase to the next stolonization phase. However, the action on peripheral targets may be indirectly via the proventricular system, the inhibitory activity of which probably becomes inactivated periodically under endocrine influence of the prostomium. Considering all the information available, a model of the cooperation of environmental factors and endocrine factors (prostomial and proventricular hormone) in the timing of the reproductive cycle in male T. prolifera is presented.     

Phylogeny and evolutionary history of the Aplodontoidea (Mammalia: Rodentia)

Athough over a hundred species of fossil aplodontoids have been described since the extant species, Aplodontia rufa (the mountain beaver), was first described by Rafinesque in 1817, a thorough survey of the relationships among all the species in this clade has not been undertaken since McGrew's study in 1941. Here, a complete phylogenetic analysis of all published species of aplodontoids is used to reconstruct the evolutionary relationships within the clade, and to present an updated classification of the Aplodontoidea. Several of the traditionally recognized subfamilies are found to be paraphyletic, namely the Prosciurinae, the Allomyinae, and the Meniscomyinae. Others, however, including the Aplodontinae and the Mylagaulidae, appear to be monophyletic. These latter two taxa, which include all of the hypsodont members of the aplodontoid clade, seem to be sister taxa. The history of the aplodontoid clade shows several episodes of rapid diversification in the Early Oligocene, the Late Oligocene, and the Early to Middle Miocene. The Ansomyinae and Aplodontinae show comparatively low speciation rates. The patterns of change in morphology and evolutionary rates suggest a need for a more detailed study of the causes of diversification, extinction, and ecological change in this lineage.  © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society, 2008, 153 , 769–838.     

Phylogeny of Syllidae (Polychaeta) based on combined molecular analysis of nuclear and mitochondrial genes

The phylogeny of Syllidae is assessed in a combined analysis of molecular data from nuclear 18S rDNA and mitochondrial 16S rDNA and cytochrome c oxidase subunit I. In total, 103 terminal taxa are examined: 88 syllids in the four classical subfamilies Eusyllinae, Exogoninae, Syllinae and Autolytinae, as well as 15 outgroup taxa from Phyllodocida and Eunicida. Maximum parsimony analysis of the combined data set indicates that Syllidae, as currently delineated, is monophyletic, though not with very high support values. Astreptosyllis Kudenov & Dorsey, 1982, Streptosyllis Webster & Benedict, 1884 and SyllidesÖrsted, 1845 comprise a monophyletic group well differentiated from the rest of the Syllidae. The subfamilies Autolytinae and Syllinae are monophyletic. Exogoninae is monophyletic, although not well supported, and Eusyllinae is clearly paraphyletic. Results corroborate previous studies about the evolution of reproductive modes in that epigamy is the plesiomorphic condition and schizogamy appeared independently in Autolytinae and Syllinae. © The Willi Hennig Society 2007.     

Musculature in polychaetes: comparison of Myrianida prolifera (Syllidae) and Sphaerodoropsis sp. (Sphaerodoridae)

Abstract. The relationship of the polychaete taxa Syllidae and Sphaerodoridae within Phyllodocida is still unresolved: phylogenetic analyses either show them as sister groups or more widely separated. The present article aims to provide information about the structure of the muscular system that could be essential for understanding their relationship. A crucial point is whether the body wall contains circular muscles, which has recently been shown to be absent in more taxa than previously known. The F-actin filaments in members of Myrianida prolifera (Syllidae) and Sphaerodoropsis sp. (Sphaerodoridae) were labeled with phalloidin and their three-dimensional relationships reconstructed by means of confocal laser scanning microscopy. Among the noteworthy differences that emerged between the species are (1) members of M. prolifera possess four, those of Sphaerodoropsis sp. eight, longitudinal muscle strands; (2) the body wall in M. prolifera contains transverse fibers in a typical, supralongitudinal position, while in Sphaerodoropsis sp., corresponding fibers lie beneath the longitudinal strands; (3) pro- and peristomium in M. prolifera have no distinct F-actin fibers, while five longitudinal pairs and three single transverse muscular fibers shape the anterior end in Sphaerodoropsis sp.; (4) the proventricle of M. prolifera comprises primarily radial muscle fibers arranged in distinct rows, while in Sphaerodoropsis sp. the axial proboscis consists of longitudinal and circular fibers and radial fibers are lacking; (5) in M. prolifera, the proximal and distal sections of the two anteriormost pairs of dorsal cirri possess longitudinal myofilaments, which are separate from the body wall musculature; by contrast, all appendages in Sphaerodoropsis sp. do not; (6) both species have bracing muscles: in M. prolifera they are positioned above the longitudinal fibers, whereas in Sphaerodoropsis sp. they are uniquely positioned between longitudinal and sublongitudinal transverse fibers. These results do not support a sister-group relationship of Syllidae and Sphaerodoridae. In addition, Sphaerodoropsis sp. is yet another example in the list of polychaetes lacking typical circular muscles in the body wall.     

The Unique Adaptation of the Life Cycle of the Coelomic Gregarine Diplauxis hatti to its Host Perinereis cultrifera (Annelida,Polychaeta): an Experimental and Ultrastructural Study

ABSTRACT. The coelomic gregarine Diplauxis hatti exhibits a unique adaptation of its life cycle to its polychaete host Perinereis cultrifera. Experimental and ultrastructural observations on natural populations from the English Channel showed that release of parasite spores is concomitant with the polychaete spawning. As the development of P. cultrifera is direct, the notochete larva ingest parts of the jelly coat covered with numerous sporocysts of D. hatti during hatching. Transepithelial migration of the sporozoites takes place in the gut of three‐ or four‐segment notochete larvae and syzygies of about 20 μm are observed in the coelom. Growth of these young syzygies is slow: after 18–24 mo they reach only 60–70 μm. They exhibit active pendular movements. In the English Channel, female and male gametogenesis of P. cultrifera begins at 19 mo and 2 yr, respectively; the somatic transformations (epitoky) in the last 4 mo of their 3‐year life. During epitoky, the syzygies undergo an impressive growth and reach 700–800 μm within a few weeks. A shift from pendular to active peristaltic motility is observed when the syzygies reach 200–250 μm. When gamogony occurs, syncytial nuclear divisions are initiated and cellularization produces hundred to thousands of male and female gametes of similar size. The male gametes exhibit a flagellum with 3+0 axoneme. The mixing of the gametes (“danse des gametes”) and fertilization are observed during 4–5 h. Zygotes differentiate sporoblasts with eight sporozoites. The sporozoites exhibit the canonical structure of Apicomplexa, a polarized cell with micronemes and rhoptries.     

Giant pelagic larvae of Phyllodocidae (Polychaeta,Annelida)

The microscopic anatomy of giant pelagic larvae of Phyllodocidae was studied using routine histological, SEM, and TEM techniques. The larvae consist of two distinct regions: a large spherical trochophore measuring up to 2 mm in diameter and a posterior, long (up to 10 mm length), narrow rudiment of the adult body with up to 120 segments. The larvae have an unusual mixture of larval and adult features, including a very complex, well-developed brain and ganglia in the ventral nerve cord, and only a single pair of protonephridia located in the hyposphere of the trochophore. A muscular pharynx is not developed. The intestinal wall, especially in the trochophore region, consists of endodermal cells containing considerable nutritive material in the form of yolk-like globular inclusions. The digestive tract of all larvae was empty. The position of the frontal sensory organ and the prototroch, the structure of the parapodia and setae, and the three pairs of tentacular cirri dictate inclusion of the larvae in the family Phyllodocidae. The relatively enormous size and unusual pattern of development of the adult body may be adaptations for a long pelagic life and rapid settlement of the species, which inhabits slopes of islands and underwater mounts located far apart. J. Morphol. 238:93–107, 1998. © 1998 Wiley-Liss, Inc.     

Phylogeny of the Cocculinoidea (Mollusca, Gastropoda)

Abstract. The superfamily Cocculinoidea is a group of marine, deep-water, limpet-like gastropods. Recent speculation surrounding their affinities has concentrated on their placement within the Gastropoda. However, phylogenetic relationships within the Cocculinoidea, especially the monophyly of families and genera within the group, remain poorly understood. Phylogenetic analysis of 31 morphological characters for 15 cocculinoidean taxa and 2 outgroups resulted in a single most parsimonious tree, length=70, CI=0.62, and RI=0.71. Monophyly of the Cocculinoidea, Cocculinidae, and the genera Cocculina and Coccopigya was supported; Paracocculina and Coccocrater were found to be paraphyletic. Character optimization demonstrates that many characters often cited as diagnostic of various taxa, are often homoplastic and/or synapomorphies at different hierarchical levels.     

Evolution of interstitial Polychaeta (Annelida)

An update of the systematics is given for the eight most important interstitial polychaete families: Diurodrilidae, Nerillidae, Protodrilidae, Protodriloididae, Saccocirridae, Parergodrilidae, Polygordidae and Psammodrilidae. Additional information and new observations are presented for the Diurodrilidae, Nerillidae and Psammodrilidae. Three new supplementary evolutionary hypotheses for these families are here suggested: (I) basal position of Diurodrilidae in Polychaeta, (2) evolution of Nerillidae in mud, and (3) evolution from meio- to macrofaunal forms of Psammodrilidae.     

Revision of Pseudonereis (Polychaeta, Nereididae)

A taxonomic revision of Pseudonereis (Polychaeta, Nereididae) shows that some of the described taxa are very similar in most morphological characteristics. The revision includes all ten taxa considered valid, and are redescribed from type material. Lectotypes are designated for Pseudonereis anomala Gravier, 1901, Pseudonereis noodti (Hartmann-Schröder, 1962) and Pseudonereis trimaculata Horst, 1924. The widely geographically distributed and well-known P. gallapagensis Kinberg, 1865 and P. variegata ( Grube, 1857 ) show striking morphological resemblance to less well-known taxa with similar distribution. Paragnath variation in populations of P. anomala is discussed relating to its geographical distribution. Pseudonereis trimaculata is recorded from Australia for the first time. Taxa belonging to Pseudonereis are predominantly tropical and subtropical. A cladistic analysis using parsimony is included to test for monophyly of Pseudonereis . A monophyletic clade including all Pseudonereis taxa is given low bootstrap support. This clade is supported by the synapomorphies: presence of paragnaths in closely spaced comb-like rows on the maxillary ring on the pharynx, and presence of p-bar paragnaths in Areas II–IV and VII–VIII. Several of the included taxa share the shield-shaped paragnath in Area VI, which serves to distinguish Pseudonereis spp. from Perinereis spp. Paragnaths of the type p-bars and shield-shaped bar is described for the first time; the latter character is different from the smooth bar-shaped paragnaths in Area VI as has previously been described in these taxa.  © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society , 2007, 150 , 145–176.     

Unusual modes of oogenesis and brooding in bivalves: the case of Gaimardia trapesina (Mollusca: Gaimardiidae)

Abstract. I describe an unusual case of follicular oogenesis in a bivalve, Gaimardia trapesina , a common marine bivalve from the Magellan Region and adjacent Sub-Antarctic waters, whose members brood their developing larvae. The gonad in G. trapesina is an acinus organ that infiltrates the perivisceral connective tissue; the walls of the acini are formed by tall, slender cells with distal nuclei, supported by a thin conjunctive tissue layer. At the onset of vitellogenesis, each developing oocyte becomes surrounded by a one-cell-thick layer of follicle cells, which may originate from the wall of the acinus. The cells form a follicle that completely encompasses single oocytes, except at the basal zone, where oocytes are in contact with the acinus wall. The follicle persists beyond the end of vitellogenesis and spawning. After gamete release, the persistent follicle participates in the attachment of ova and developing embryos to the interfilamental junctions of the inner and outer demibranchs of the gill, where embryos are incubated until hatching as late-stage pediveliger larvae. Ripe eggs are large (∼250 μm diameter), suggesting that development is entirely lecithotrophic. The follicle cells that mediate connections between developing embryos and the maternal individual probably have a mechanical role only, providing support and possibly facilitating the accommodation of a large number of embryos to maximize the branchial space available for brooding.     

Phylogeny and classification of Muscini (Diptera, Muscidae)

Worldwide in distribution, the tribe Muscini comprises 21 accepted genera and about 350 species. In the present study, a cladistic analysis based upon adult morphological characters is carried out in order to discuss the monophyly of the tribe and its genera, the intergeneric relationships and, in some cases, also the intrageneric relationships. As a result, Muscini is supported as a monophyletic tribe sister-group of Stomoxyini. Except for Morellia Robineau-Desvoidy, Curranosia Paterson, and Eudasyphora Townsend, all the remaining genera are monophyletic. The results are dubious for Polietes Rondani, which was then provisionally kept unchanged. Morellia was broadened to include the Neotropical endemic genera Parapyrellia Townsend, Trichomorellia Stein, and Xenomorellia Malloch. Therefore, a new classification is proposed for Morellia in which it is divided into four subgenera: Morellia s.s. , Parapyrellia , Trichomorellia , and Xenomorellia . Furthermore, the previously proposed subgenus Dasysterna Zimin is given new status as a genus; however, as it is preoccupied by Dasysterna Dejean, the new replacement name Ziminellia nom. nov. is proposed herewith. Eudasyphora was found to be a paraphyletic group relative to Dasyphora Robineau-Desvoidy; both genera are hence synonymized, and Dasyphora is classified in three subgenera: Dasyphora s.s. , Eudasyphora , and Rypellia Malloch. The analysis demonstrated that the traditional classification of Musca Linnaeus into subgenera is artificial and, moreover, that the use of characters from male genitalia could be strongly informative for classifying the genus in phylogeny-supported species groups. Finally, the new classification proposal for Muscini recognizes 18 genera and, furthermore, two undescribed genus-ranked taxa are indicated.  © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society , 2007, 149 , 493–532.     

Gametogenesis and reproduction in Hormogaster elisae (Oligochaeta, Hormogastridae)

Abstract. The gametogenesis of the earthworm Hormogaster elisae , an endemic species of central Spain, was studied over a 12-month period. The ovaries, seminal vesicles, male funnels, and spermathecae of 156 specimens were removed by dissection. Microscopic analysis of these organs allowed the study of the gametogenic cycle, and provided information on copulation method and reproductive cycle. Individuals of H. elisae have two pairs of spermathecae, the posterior of which is more important for the storage of sperm. In summer, the earthworms enter quiescence, and oogenesis and spermatogenesis are interrupted. The gametogenic processes occur mainly during autumn and winter. Ovules are produced during all months except August and September, and the spermathecae contain sperm over the full 12-month period. There is a reproductive peak in spring, when most ovules are produced and the clitellum is most developed.