Pairs Of Tentacular Cirri Research Articles

Morphology and sexual dimorphism of living mature adults of Amphiduros fuscescens (Marenzeller, 1875) (Annelida, Hesionidae, Amphidurine), first reported for the Iberian Peninsula.

BackgroundTo date, the genus Amphiduros (Annelida: Hesionidae: Amphidurine) is considered as monotypic. Its single species, Amphiduros fuscescens (Marenzeller, 1875), is well characterised by lacking proboscideal papillae and emerging acicular chaetae, as well as by having three antennae, eight pairs of tentacular cirri and inflated dorsal cirri with characteristic alternating length and colour (transparent, with median orange band and white tips) in live animals.New informationThree specimens, one male and two females, were found below boulders at 5–7 m depth in Punta Santa Anna, Blanes and Cala Maset, Sant Feliu de Guixols (Catalan Sea, NW Mediterranean, Iberian Peninsula). Our finding allowed us to describe different, unreported morphological traits and lead us to support the existence of sexual dimorphism (in terms of colouring, cirri morphology and distribution of sexual products along the body). Despite A. fuscescens having been previously reported from the Atlantic and the Mediterranean (particularly in SE French coasts), the specimens from Blanes represent the first record of the species from the Iberian Peninsula. In addition, our molecular results strongly support that Amphiduros pacificus Hartman, 1961 from California (currently synonymised with A. fuscescens) requires to be re-described and reinstalled as a valid species. In turn, our morphological observations support suggesting all other non-Mediterranean reports of A. fuscescens, including the species still under synonymy (i.e. Amphidrornus izukai Hessle, 1925 and Amphidromus setosus Hessle, 1925) as likely being a cryptic species complex whose the taxonomic status requires further assessment.

<p class="ZootaxaTitle"><strong>Transformative nototchaetae: larval development and metamorphosis in <em>Chrysopetalum </em>spp. (Chrysopetalinae: Chrysopetalidae: Annelida)</strong></p>

The morphology of an early nectochaete larva belonging to Chrysopetalum sp. is aligned with that of a planktotrophic larva at a crucial stage of benthic settlement: an entire provisional spinose notochaetal scleritome, large episphere with prostomial nascent sensory structures and larval podia and cirri of the anterior two segments in transition. Morphological sequences of post-larvae and juveniles, common to a number of Chrysopetalum species, indicate that long, slender, provisional, camerate notochaetal spines are replaced during metamorphosis and growth with an entire adult, camerate notochaetal scleritome consisting of broad paleae with internal, longitudinal ribs. The Chrysopetalum sp. six segment larva supports achaetous notopodia I and chaetous notopodia II, each with a pair of dorsal cirri, ie. 4 cirri in total; segment II has acirrose neuropodia. Individuals of post-larvae and juvenile Chrysopetalum species, 8–15 segments, possess a total of 6 cirri on segments I and II: segment I with a pair of tentacular dorsal cirri and the formation of a pair of tentacular ventral cirri, and segment II comprising a pair of dorsal cirri, spinous notochaetae and acirrose neuropodia. During metamorphosis the acirrous neuropodia of segment II are reabsorbed and replaced in stages with a pair of ventral tentacular cirri until the adult state is achieved: achaetous segment 1 with two pairs of tentacular cirri and segment II similar, ie. total of 8 cirri. The cirri arrangement of segments I and II before final metamorphosis in post-larval stages of Chrysopetalum species is, interestingly, that described for adults in the majority of other Chrysopetalinae taxa. Ontogenetic developmental processes of formation and loss of acirrose neuropodia and replacement of spinose larval notochaetae with adult paleae observed in Chrysopetalum species are compared with species of other taxa of the Chrysopetalinae.

Description of a new species of Namalycastis (Annelida: Nereididae:Namanereidinae) from the Brazilian coast with a phylogeny of the genus.

The subfamily Namanereidinae represents one of the few groups of Polychaeta strongly adapted to low salinity and freshwater. Recently, some new species of the subfamily have been described, but no new phylogenetic analyses for the group have been undertaken since 1999. Here, we describe a new species of Namanereidinae, Namalycastis caetensis sp. nov., and provide a morphology-based phylogenetic analysis of the genus Namalycastis with the aim of assessing the evolutionary relationships for this new species. The designation of this new species is supported by the presence of elongated falcigers (also known as pseudospinigers, an unusual character in the genus), lack of an anterior cleft in the prostomium, slightly indistinct cirrophores, four pairs of tentacular cirri, and subconical acicular ligulae. Our results suggest that Namalycastis caetensis is closely related to N. geayi and N. fauveli. The existence of poorly-characterized species, from a morphological and molecular point of view, still limits our understanding of Namanereidinae relationships.

A new species of Amphictene (Annelida, Pectinariidae) from the Gulf of Mexico, with a redescription of Amphictene guatemalensis (Nilsson, 1928)

The genus Amphictene is reported for the first time from Mexico. Previous records for America are restricted to Brazil (Amphictene catharinensis) (Grube, 1870), and Guatemala (Amphictene guatemalensis) (Nilsson, 1928). In this paper we describe a new species, Amphictene helenae sp. n., characterized by the presence of three pairs of tentacular cirri, while other species have only two pairs. The new species is closely similar to Amphictene catharinensis, and can be distinguished by the presence of a circular group of glandular papillae inserted between the lines of glandular cirri present from the second segment. Amphictene guatemalensis is redescribed based on type material; it differs from the new species in the presence of two pairs of tentacular cirri on segments 1 and 2, six pairs of glandular cirri on the third segment, and four glandular lobes fused in pairs on the fourth segment.

Namalycastis occulta n. sp. and a new record of N. borealis (Polychaeta: Nereididae: Namanereidinae) from the Northwestern Caribbean Sea.

The nereidid polychaete genus Namalycastis Hartman, 1959 has been recorded almost exclusively in non-marine environments. This genus includes species having four pairs of tentacular cirri, and its species mainly differ by the relative size of dorsal cirri in posterior chaetigers. Namalycastis occulta n. sp. is described based upon non-mature and mature specimens collected in the intertidal from Chetumal Bay, Quintana Roo, Mexico. Its distinctive features are the lack of notopodial spinigers, eyes, and teeth in the mandibles. Namalycastis borealis Glasby was found in Tamalcab Island, Chetumal Bay and it is the first record for Mexico. Analyses of the intraspecific variability, a key to the known species in the Grand Caribbean region, and commentaries about some taxonomic topics are also included.

ANOPLOSYLLINAE Y EUSYLLINAE (POLYCHAETA: SYLLIDAE) DEL GRAN CARIBE, CON COMENTARIOS SOBRE MATERIALES TIPO Y NO TIPO

Anoplosyllinae possesses palps basally fused, without central surcus, three antennae, and two pairs of tentacular cirri, pharynx straight, short and unarmed. Antennae, tentaculars cirri, and first dorsal cirri smooth, the rest can be smooth or semiarticulate. Eusyllinae possesses palps fused, partially or free, nuchal organs often large, distinct, one or two pairs of tentacular cirri, dorsal cirri variable in length, usually smooth, ventral cirri present, pharynx usually straight, with teeth or unarmed. The objective of this study was to check type and non-type material of the species recorded from the Grand Caribbean. One hundred and eighty six specimens were examined; 135 collected from the Mexican Caribbean, and 51 deposited in museums; in total 9 genera and 17 species of both subfamilies were examined. Type material included Odontosyllis luminosa San Martin, 1990; Opisthodonta luquei (San Martin, 1990); Perkinsyllis spinisetosa (San Martin, 1990); Syllides caribica Licher, 1996; S. gomezi Sail Martin, 1990, and S. papillosa Hartmann-Schroder, 1960. Non-type specimens included Amblyosyllis algefnae Viguier, 1886; A. dorsigera Claparede, 1864; A. madeirensis Langerhans, 1879; Eusyllis kupfferi Langerhans, 1879; Odontosyllis detecta Augener, 1913; O. fulgurans (Audouin and Milne-Edwards, 1883); Sinmerosyllis lamelligera (Saint-Joseph, 1886); Syllides edentulus Claparede, 1868; S. fulvus (Marion y Bobretzky, 1875, and Westheidesyllis gesae (Perkins, 1981).

On the phylogeny of the Phyllodocidae (Polychaeta Annelida): an alternative

The phylogeny of the Phyllodocidae (Polychaeta Annelida) is examined in an analysis which includes previously unnoticed characters of the nervous system. Concentrating on four problems of importance in understanding the phylogeny of the family, a study of the nervous system demonstrated that: 1. A median antenna, such as that present in species of Eulalia, is not homologous to the nuchal papilla of, for example, Eteone and Phyllodoce; 2. Nuchal organs, presumably found in all phyllodocids, are basically homologous, but four separate types may be recognized; 3. The anterior concentration of the first segments (particularly their tentacular cirri), which is evident in most phyllodocids, is accompanied by different alterations of the ventral nervous system. The polarities of these changes are not self-evident; 4. A study of the ventral nervous system of Eteone reveals that the first apparent segment, bearing two pairs of tentacular cirri, must be regarded as homologous to the second segment of all other phyllodocids. Furthermore, this genus descended from forms in which a segment was present anterior to the first apparent segment, the first two segments possibly bearing tightly packed tentacular cirri. In connection with other characters, this information was used to produce a cladogram, which has some surprising features. The most unexpected result is the prediction that Eteone is the sister group of a taxon containing the genera Paranaitis, Chaetoparia, and Phyllodoce. The results are discussed and compared to those of other investigators.

The Namanereidinae (Polychaeta: Nereididae). Part 1. Taxonomy and phylogeny

A cladistic analysis and taxonomic revision of the Namanereidinae (Nereididae: Polychaeta) is presented. The cladistic analysis utilising 39 morphological characters (76 apomorphic states) yielded 10,000 minimal-length trees and a highly unresolved Strict Consensus tree. However, monophyly of the Namanereidinae is supported and two clades are identified: Namalycastis containing 18 species and Namanereis containing 15 species. The monospecific genus Lycastoides, represented by L. alticola Johnson, is too poorly known to be included in the analysis. Classification of the subfamily is modified to reflect the phylogeny. Thus, Namalycastis includes large-bodied species having four pairs of tentacular cirri; autapomorphies include the presence of short, subconical antennae and enlarged, flattened and leaf-like posterior cirrophores. Namanereis includes smaller-bodied species having three or four pairs of tentacular cirri; autapomorphies include the absence of dorsal cirrophores, absence of notosetae and a tripartite pygidium. Cryptonereis Gibbs, Lycastella Feuerborn, Lycastilla Solis-Weiss & Espinasa and Lycastopsis Augener become junior synonyms of Namanereis. Thirty-six species are described, including seven new species of Namalycastis (N. arista n.sp., N. borealis n.sp., N. elobeyensis n.sp., N. intermedia n.sp., N. macroplatis n.sp., N. multiseta n.sp., N. nicoleae n.sp.), four new species of Namanereis (N. minuta n.sp., N. serratis n.sp., N. stocki n.sp., N. sublittoralis n.sp.), and three widespread species groups ( Namalycastis abiuma, Namanereis littoralis, N. quadraticeps). Fourteen species are newly placed into synonymy, Lycastis maxillo-falciformis Harms, L. maxillo-ovata Harms, L. maxillo-robusta Harms, Lycastis meraukensis Horst, L. nipae Pflugfelder, L. ouanaryensis Gravier, L. ranauensis Feuerborn, L. vivax Pflugfelder, Lycastopsis augeneri Okuda, L. tecolutlensis Rioja, Namalycastis rigida Pillai, N. tachinensis Rosenfeldt, N. vuwaensis Ryan, and Namanereis littoralis Hutchings & Turvey. A neotype is designated for Namalycastis hawaiiensis (Johnson), and lectotypes are designated for Namalycastis geayi (Gravier), N. senegalensis (Saint-Joseph), N. terrestris (Pflugfelder), Namanereis amboinensis (Pflugfelder) and N. littoralis (Grube). Keys to genera and species are given. Namanereidinae are generally confined to the tropics and subtropics. Maximum species-diversity occurs in the Caribbean and Indo-Pacific, in particular in coastal areas subjected to recent uplifting, where both littoral-zone and freshwater (riparian and subterranean) forms occur. Phylogenetic results indicate that in both Namalycastis and Namanereis there is a preference for freshwater habitats among species with apomorphic traits (corollary being that marine habitats are favoured by the plesiomorphic members). This suggests that the ancestor of the Namanereidinae was a euryhaline coastal species.

Phylogeny and classification of the Phyllodocidae (Polychaeta)

The phylogenetic relationships of the benthic phyllodocid genera are estimated by a parsimony analysis based on 26 morphological characters. It is concluded that the cephalization within Eteone has led to a reduction of segment 1 and loss of the first pair of tentacular cirri. Biramous parapodia (like in Austrophyllum and Notophyllum) constitute an ancestral state, which has evolved independently also within Phyllodoce. A new subfamily, Notophyllinae, is erected, and the two additional subfamilies, Phyllodocinae and Eteoninae, are redefined. Pareteoninae is treated as a junior synonym to Phyllodocinae, and Lugiinae as a nomen dubium. A number of genera are redefined and new combinations introduced. Based on type material Zverlinum and Phyllouschakovius are synonymized with Phyllodoce, Nipponophyllum with Notophyllym, Vitiaziphyllum with Eumida, Pareteone, Eulalia (Euphylla) and Compsanaitis with Paranaitis. More tentatively proposed synonymizations include Bergstroemia with Austrophyllum, Prophyllodoce with Phyllodoce, and Pseudeulalia with Protomystides. Eulalia lapsus is proposed as a replacement name for E. anoculata Fauchald, 1972, junior homonym to E. anoculata Hartman & Fauchald, 1971, and a number of species are synonymized and new combinations introduced. A checklist of phyllodocids together with information on the location of their type specimens is included.

Ultrastructural investigations of presumed photoreceptors as a means of discrimination and identification of closely related species of the genus Microphthalmus (Polychaeta, Hesionidae)

Differences in the ultrastructure of presumed photoreceptors of three morphologically similar Microphthalmus populations on the opposite sides of the Atlantic (German North Sea coast and coasts of North Carolina and Massachusetts) suggest the existence of three different species. Only the European M. listensis possesses three pairs of prostomial eyes, of which one pair has rhabdomeric receptors and pigment cells. The two other pairs are unpigmented and can be found in all three species. The frontal one has ciliary receptors, the posterior one rhabdomeric sensory cells. An additional unpaired potential photoreceptor organ in the segment with the first pair of tentacular cirri is present in all individuals of this species complex. It has a relatively high number of cilia with numerous microvillar projections. — For each type of ocellus there are slight but distinct and constant differences among the species such as relative position of sensory cells, presence of dilations of the ciliary shafts, number of cilia, and shape of the sensory cells. Presence of both ciliary and rhabdomeric light-sensitive cells is discussed with reference to various theories of the evolution of photoreceptors.

Paragyptis margaretae, new genus and species of Hesionidae (Annelida: Polychaeta) from St. Margaret's Bay, Nova Scotia

Paragyptis margaretae n.g., n.sp. is described from St. Margaret's Bay, Nova Scotia. It is the only genus of the family Hesionidae with eight pairs of tentacular cirri, two antennae, and strongly biramous parapodia. Its relationship to other members of the family is discussed.