Systematics and evolution of syllids (Annelida,Syllidae)

A large, combined phylogenetic analysis (including morphological and molecular data from 18S rDNA, 16S rDNA and cytochrome c oxidase subunit I), with the highest number of species and genera of Syllidae studied to date (213 terminals), is examined. The data were explored with different parameters and optimality criteria (parsimony, likelihood, and bayesian inference). The monophyly of Syllidae and most of the traditional subfamilies is supported. The subfamily Eusyllinae is polyphyletic, as currently delineated, but it is herein reorganized and its diagnosis modified to be a valid group. Additional well supported clades arise. The phylogenetic relationships of the well known and established genera, as well as several enigmatic genera (e.g. Anguillosyllis, Paraopisthosyllis and Parahaplosyllis), the position of which in syllid taxonomy was uncertain or dubious to date, are clarified. The results corroborate previous hypotheses about the evolution of the reproductive and brooding modes. Within Syllinae, the nature of the stolon is phylogenetically informative. The classification of the whole family is revised and discussed on the basis of this phylogenetic hypothesis. © The Willi Hennig Society 2011.     

Phylogeny and reproduction in Syllidae (Polychaeta)

The phylogeny of 12 representatives of the four syllid subfamilies is analysed using 44 morphological characters and 96 character states. The analysis is designed to answer two questions: are the four subfamilies monophyletic, and how are the different reproductive strategies related? Syllids show two modes of reproduction, epigamy and schizogamy. Epigamy is mainly constrained to two of the four subfamilies, Eusyllinae and Exogoninae but occurs also in some members of Autolytinae. Schizogamy can be of two types–scissiparity and gemmiparity–and both types are found in Syllinae and Autolytinae. Several modes of brood protection also occur in the family; in some epigamous species the eggs and even juveniles are attached to the main animal, whereas in brooding schizogamous species the stolons care for the young. Brood protection appears in Exogoninae, a few species of Eusyllinae, and some Autolytinae. The resulting tree indicates that members exhibiting brood protection are constrained to one clade, and that it is uncertain whether epigamy or schizogamy is the plesiomorphic reproductive mode. Three of the four subfamilies, Autolytinae, Exogoninae and Syllinae, are supported in the analysis whereas Eusyllinae is found to be polyphyletic.     

Autolytinae, Eusyllinae an Exogoninae (Syllidae: Polychaeta) from Coiba National Park, Panama)

This is the second paper on the Syllidae (Polychaeta) from hard substrata of the Coiba National Park (Pacific coast of Panama) (the first paper treated Syllinae). On this second paper nineteen species belonging to eleven genera of the subfamilies Autolytinae, Eusyllinae and Exogoninae (Syllidae: Polychaeta) are reported. The samples were collected by SCUBA diving, either by removing 4 kg blocks of dead coral (Pocillopora spp.) or scraping off 25 x 25 cm quadrats of Telesto multiflora or algae (Dyctiota cf. flavellata, Padina cf. durvillaei and another currently unidentified species). They were collected during four expeditions carried out between 1996 and 1998. Four species are newly reported for the Eastern Pacific: Eusyllis lamelligera Marion & Bobretzky, 1875, Exogone exmouthensis Hartmann-Schr?der, 1980, Proceraea cf. cornuta (Agassiz, 1863) and Sphaerosyllis (S.) magnidentata Perkins, 1981. Ten species are reported for the first time from the Central America Pacific coast: Amblyosyllis cf. granosa Ehlers, 1897 (sensu Westheide 1974), Amblyosyllis speciosa Izuka, 1912, Autolytus multidenticulatus Westheide, 1974, Exogone naidinoides Westheide, 1974, Grubeosyllis concinna (Westheide, 1974), Odontosyllis fulgurans (Audouin & Milne Edward, 1833), Opisthodonta mitchelli Kudenov & Harris, 1995, Pionosyllis articulata Kudenov & Harris, 1995, Sphaerosyllis (S.) californiensis Hartman, 1966 and Syllides cf. reishi Dorsey, 1978. The family Syllidae is represented in the Coiba National Park by 14% of cosmopolitan species, 14% of circumtropical species, 22% of Atlantic and Pacific species and 25% of Pacific species restricted to warm waters. In samples of dead coral the dominant species are S. armillaris (Muller, 1771) and S. gracilis (Campoy, 1982); in samples of telestaceans Grubeosyllis concinna dominates.     

Indo-Pacific Syllidae (Annelida,Phyllodocida) share an evolutionary history

The geographic distribution of three intriguing genera of Syllidae (Annelida, Phyllodocida), Alcyonosyllis, Paraopisthosyllis and Megasyllis, is restricted to the Pacific Ocean, Indian Ocean and the Red Sea. In this study new material of several species in all three genera is identified, and the distributions of the species and genera refined; four species of Alcyonosyllis were found to have increased ranges. Additionally, one new species of Paraopisthosyllis is described. Paraopisthosyllis pardus sp. nov. is characterized by having long bidentate bladed-chaetae, segments covered by small papillae, and a colour pattern consisting in dark red-brown antennae and dorsal cirri and several transversal dark red-brown lines per segment. The three genera share several striking morphological characteristics, such as alternation in the arrangement of dorsal cirri, wide segments with secondary annuli and bright, contrasting colour patterns. Alcyonosyllis species are found in association with other organisms, most noticeably anthozoans, whereas members of Paraopisthosyllis and Megasyllis are free living. Molecular information (sequences of DNA) from Alcyonosyllis species (including the type species, A. phili), and the type of Megasyllis (M. corruscans) is included herein for the first time in a phylogenetic analysis. A phylogenetic analysis performed through different methods (Maximum parsimony and Maximum likelihood) using sequences of three genes (18S, 16S and COI) reveals that all the three genera form a monophyletic group within Syllidae, with several synapomorphies, and a common ancestor probably from the Indo-Pacific. Their geographic distribution pattern, the relationships between these genera and the rest of syllids, and the symbiosis in Alcyonosyllis are discussed.     

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.     

Infrastructural study of photoreceptor organs in the larvae of two Syllidae (Annelida, Polycheta)

The ultrastructure of the larval eyes of two Syllidae: Syllis amica (subfamily: Syllinae) and Odontosyllis ctenostoma (subfamily: Eusyllinae) were studied. These eyes are composed of a pigmented supportive cell and one or two sensory cells. A dense body, corresponding to a secreted lens, can be observed in the ocular cavity formed by the supportive cell. Such a structure present in O. ctenostoma adult eyes has never been described in S. amica adult eyes.     

The culture, experimental taxonomy, and comparative morphology of the planktonic stages of Norfolk autolytoids (Polychaeta: Syllidae: Autolytinae)

Stocks of two species were cultured as described to yield stolons for mating trials with one another and with planktonic stolons of unknown origins, which were progressively linked to known taxa by mating reactions and/or morphological comparisons. The most hardy and sexually vigorous species in culture was the low-intertidal Proceraea cornuta (Agassiz); fewer results were obtained with the much less hardy and principally offshore Autolytus brachycephalus (von Marenzeller), and mating was seen once in A. alexandri Malmgren. Healthy males of each species showed all or part of a consistent pattern of mating responses to a pheromone from preovulatory (= virgin) or newly postovulatory homospecific females, but none whatever to heterospecific females. Planktonic males, possibly of A. langerhansi Gidholm, reacted anomalously to virgin females of the closely allied A. brachycephalus. The stolons of both sexes fell into three groups, with respectively 14 (A. alexandri only), 6 (the genera Proceraea and Procerastea, distinguished from each other by the degree of development of the dorsal cirri and the number of eggbags in the female), and 3 or fewer (Autolytus of the prolifer-group) setigers in the front region. These groups also have different arrangements of the appendages on and immediately behind the stolon head; the numbers of setigers in their middle regions and tails show variations which are not statistically significant. The sexual stages in North Norfolk plankton comprise two species found only in winter and spring (Proceraea prismatica and A. alexandri), one found all year but mainly in spring (P. cornuta), one from late spring to early autumn (A. brachycephalus), and two found only in summer (Procerastea halleziana and A. ?langerhansi); the relationship between seasonally, zoogeography, and water-temperature is briefly discussed.     

A new genus and species of the Syllidae (Annelida, Polychaeta) from south India

A syllid species new to science is described from intertidal sandy sediments on the cast coast of India, for which a new genus is erected: Psammosyllis aliceae gen. et sp.n. Incorporation into either the Eusyllinae or the Exogoninae is unresolved, because it possesses characters of both of these poorly defined subfamilies.     

Phylogeny of Vestimentifera (Siboglinidae, Annelida) inferred from morphology

Vestimentifera, formerly considered a phylum, are here included in the annelid clade Siboglinidae which also encompasses Frenulata and Sclerolinum . All Siboglinidae inhabit reducing habitats, mostly in the deep sea. Vestimentifera are known from hydrothermal vents and cold seeps. Cladistic analyses of vestimentiferan relationships are performed on three levels: (1) among the vestimentiferan species, (2) among the reconstructed ancestral vestimentiferan and other siboglinids and (3) on the level of the families included in the annelidan clade Sabellida. The monophyly of vestimentiferans is confirmed in all analyses. A group of exclusively vent-inhabiting species forms a derived monophyletic clade. The sister group to the vent clade is the Escarpia complex. Lamellibrachia appears to be paraphyletic. Except for the paraphyly of Lamellibrachia , the reconstructed pattern agrees with the molecular phylogeny based on cytochrome c oxidase subunit I. Ancient ridge systems can be invoked to explain modern day geographical distributions. The Pacific Kula Ridge that spanned the Pacific in an east–west direction during the Early Tertiary, may have been a pathway for the ancestor of the vent clade to reach the eastern Pacific. The biogeography is consistent with the recent divergence of Vestimentifera as inferred from molecular data. The reconstructed phylogeny of the Siboglinidae supports the monophyly of the Frenulata and within those, the Thecanephria and Athecanephria. In contrast to molecular and other morphological analyses, Sclerolinum appears as the sister group to the Frenulata. The family level analysis supports the sister group relationship of the Siboglinidae to a clade formed by Sabellariidae, Sabellidae and Serpulidae. Hypothesized homologies of the vestimentiferan obturaculum and vestimentum to structures in related taxa need further investigation.     

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 biogeography of the scaleless scale worm Pisione (Sigalionidae,Annelida)

Pisione is a scaleless group of small scale worms inhabiting sandy bottoms in shallow marine waters. This group was once considered rare, but now 45 described species can be characterized, among others, by their paired, segmental copulatory organs (one to multiple external pairs), which display a complexity of various accessory structures. The evolutionary significance of these unique organs was suggested in the late 1960s, but has been heavily debated since the late 1990s and remains controversial. In the present paper, we study the internal relationships within Pisione, employing combined phylogenetic analyses of both molecular and morphological data from 16 terminals of Pisione, as well as two terminals of Pisionidens, and eight additional scale worms as outgroups. Our taxon sampling covers all geographical areas where the genus has been reported, as well as most of their morphological and copulatory variability, including representatives of the “africana,” “remota,” “crassa,” and “papuensis” groups, established previously by Yamanishi. We hereby provide a first insight into the relationships of the genus, testing previously proposed hypotheses on the evolutionary significance of male copulatory structures within Pisione, while attempting to understand patterns of distribution. The phylogenetic analyses using maximum likelihood and Bayesian methods consistently recovered two large clades spanning the East Atlantic (including the Mediterranean) and the Indo‐Pacific–West Atlantic, respectively. Character optimization on our trees revealed a high degree of homoplasy in both non‐reproductive and sexual characters of Pisione, with buccal acicula found to be the sole apomorphy among the morphological features assessed herein, with none defining the biogeographical subclades within. Overall, our comparative analyses highlight the high degree of morphological variation in this widely distributed genus, rejecting previous assertions of an increasing number and complexity of copulatory structures across the genus.     

Guide and keys for the identification of Syllidae (Annelida,Phyllodocida) from the British Isles (reported and expected species)

In November 2012, a workshop was carried out on the taxonomy and systematics of the family Syllidae (Annelida: Phyllodocida) at the Dove Marine Laboratory, Cullercoats, Tynemouth, UK for the National Marine Biological Analytical Quality Control (NMBAQC) Scheme. Illustrated keys for subfamilies, genera and species found in British and Irish waters were provided for participants from the major national agencies and consultancies involved in benthic sample processing. After the workshop, we prepared updates to these keys, to include some additional species provided by participants, and some species reported from nearby areas. In this paper, we provide the revised keys to enable rapid identification of Syllidae from the seas around Britain and Ireland. One new combination, Palposyllis propeweismanni, is proposed.     

Phylogeny of Tubificidae (Annelida, Clitellata) based on mitochondrial and nuclear sequence data

The tubificid clitellates are a common component in the freshwater bottom fauna and are also the most abundant oligochaete group in marine habitats. There are over 800 described species classified in six subfamilies; Tubificinae, Limnodriloidinae, Rhyacodrilinae, Telmatodrilinae, Phallodrilinae, and Naidinae. In this study we examine the phylogenetic relationships in Tubificidae using a combination of mitochondrial 16S rDNA and nuclear 18S rDNA sequence data. Sequences were obtained from five outgroup and 56 ingroup taxa, including five of the six subfamilies of Tubificidae. The data were analysed by maximum parsimony and Bayesian inference. The resulting tree topologies are virtually without conflict. Several associations traditionally recognized within the family Tubificidae are supported, in the Bayesian analysis including a sister group relationship between Tubificinae and Limnodriloidinae. The results also indicate that Rhyacodrilinae is polyphyletic--some of its members (Heterodrilus spp.) fall into a clade with Phallodrilinae, all other groups with Naidinae. Naidinae is also polyphyletic with two rhyacodriline genera, Monopylephorus and Ainudrilus, nested within. Most of the tubificid genera included in the study are supported as monophyletic; however, Tubifex and Limnodriloides are refuted, and Tubificoides is unresolved from other tubificine taxa.     

Ecological aspects of syllids (Annelida: Polychaeta: Syllidae) on Thalassia testudinum beds in Venezuela

The spatial and temporal variations of syllids associated with the tropical Thalassia testudinum were studied at four seagrass beds in the Morrocoy National Park. The epifaunal syllids were collected at quarterly intervals throughout one year using a modified suction sampler. Possible relationships between sampling sites, months and species were evaluated by Principal Components Analysis. The spatial-temporal variability of the predominant species was tested by means of a 2-factor ANOVA with the sampling sites and months as factors. A total of 1138 individual syllids were collected, belonging to 41 species and 12 genera, of which Branchiosyllis, Exogone, Odontosyllis, Sphaerosyllis and Syllis showed the highest diversity. Spatial variations were defined by the species of Branchiosyllis (B. exilis, B. lorenae, B. oculata) whereas temporal variability was defined by certain species of Syllis(S. beneliahui, S. broomensis and S. prolifera), the latter also being the most species rich genus present. Of the 41 species found, only these six showed consistent presence–absence and abundance patterns. Species richness and abundance were significantly higher in March at all sampling sites. Collectively, the syllid fauna of the Morrocoy seagrass beds was richer than recorded from other similar habitats. These findings are discussed in relation to the physical and biotic factors that may affect the variability of syllid populations in these seagrass habitats.     

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.