Cytological aspects of haemoglobin and chlorocruorin synthesis in polychaete annelids

Summary The ultrastructure of the haematopoietic cells in the polychaetes Neoamphitrite figulus Dalyell, Lanice conchilega (Pallas), Arenicola marina (L.), Myxicola infundibulum Renier, Megalomma vesiculusom (Montagu), Sabella penicillus L., are compared: all show similarities in having well developed Golgi, granular endoplasmic reticulum and haemoglobin or chlorocruorin in vesicles, and numerous mitochondria. The porphyrin byproducts of synthesis are combined with iron as haematins within electrondense granules built up from multi-lamellar organelles. The structure of the basal lamina which alone separates the cells from the lumen of the vessels is described and evidence is presented for the method of release of the haem into the plasma by reverse pinocytosis. The cycle of synthesis within the cell is discussed and the process of haem synthesis in annelids is reviewed. The structure of the haemoglobin-containing coelomocytes of Neoamphitrite figulus is briefly described.This work was made possible by an award from the Science Research Council. We would also like to thank the Director and Staff of the Plymouth Laboratory, where some of the work was done, for their hospitality and facilities.     

Ultrastructure of gill epithelial cells of Diopatra neapolitana (Annelida,Polychaeta)

Summary The ultrastructure of gill epidermal cells of Diopatra neapolitana and their relationship with blood spaces are described. The existence of a basal infolding complex, related to the blood spaces, is also reported. A possible involvement of these cells in osmoregulation and ion interchange, apart from their well-known role in respiration, is suggested.Abbreviations bc Blood cell - bi Basal infolding - bl Basal lamina - bs Blood space - ci Cilia - cu Cuticle - db Dense body - EC Epidermal cell - Gc Golgi complex - id Interdigitation - j Junction - m Mitochondria - mv Microvilli - n Nucleus - pv Pinocytotic vesicle - rer Rough endoplasmic reticulum     

The fine structure of polychaete septate junctions

Summary Epidermal septate junctions of Nereis sp. and Cirriformia sp. fixed with OsO₄ or glutaraldehyde/OsO₄ display variable structure in electron micrographs. In transverse section the septa are often indistinct and obscured by opaque material that fills the junctional cleft. Septa (spaced at 180–280 Å) are more clearly defined in slightly oblique transverse section; they exhibit an electron lucent center and appear to be linked by arms. En face views of the junction show a honeycomb pattern. Cytoplasmic faces of junctional membranes are backed with plaques opposite the septa. Lanthanum used as a tracer delineates junctional structure in negative contrast. In transverse section a chain-like lattice is present in the junctional cleft. En face views show parallel rows of pleated elements often linked by arms into honeycomb arrays. Oblique sections demonstrate that these pleated elements are continuous with the chain-like lattice seen in transverse sections. Lanthanum does not pass entirely through the junction. Lanthanum reveals that the septa have a very intricate substructure, but it is difficult to visualize the architecture that could generate the various images presented by these junctions when seen in different orientations. However, it is clear that these junctions possess some features that are diagnostic of several supposedly different types of septate junctions in invertebrates.Supported by USPHS grants NIH 5 P01 NS-07512, NIH 2701 GM-00102, and NB-00840, and by a grant from the Pomona College Research CommitteeI thank Sarah Wurzelmann, Stanley Brown, Nancy Kelly, and Gerhard Ott for excellent technical assistance. Portions of this study were carried out while I was a Postdoctoral Fellow in the Department of Anatomy, Albert Einstein College of Medicine. I dedicate this article to Berta Scharrer as a token of appreciation and affection for her guidance, encouragement, inspiration, and example of excellence     

Polychaete meets octopus: symbiotic relationship between Spathochaeta octopodis gen. et sp. nov. (Annelida: Chrysopetalidae) and Octopus sp. (Mollusca: Octopodidae)

Marine annelids in the subfamily Calamyzinae (family Chrysopetalidae) are either symbiotic or free-living forms that have been mainly reported from deep-sea chemosynthetic systems. Symbiotic calamyzines mainly live in the mantle cavity of bivalves in hydrothermal vents or cold seeps, but one species is also found to be inserted into the epidermis of polychaetes. We found a single specimen of calamyzine polychaete on the body surface of Octopus sp. collected in the Sea of Kumano (Japan), which represents the first known record of symbiotic association between polychaetes and octopuses. We described the specimen as Spathochaeta octopodis gen. et sp. nov. Spathochaeta gen. nov. can be discriminated from other genera in Calamyzinae by the presence of spatula-shaped notochaetae and dorsal chaetal lobes. We also provided the phylogenetic position of S. octopodis gen. et sp. nov. within Chrysopetalidae based on four gene markers (COI, 16S, 18S, H3). www.zoobank.org/urn:lsid:zoobank.org:pub:A8FB15C1-31A7-4487-966B-13F10E19A373.     

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.     

The inheritance of morphological variation in Pileolaria pseudomilitaris (Polychaeta: Spirorbidae)

The genetic control of morphological variation (expressed as heritability) was examined by means of laboratory culture in Pileolaria pseudomilitaris. Fourteen of 22 traits examined were shown to have an appreciable genetic component, after an analysis of variance among groups of full siblings. The range of variability for several traits is as large within a single sibling group as the difference between described species in the family.
Comparisons among samples of P. pseudomilitaris from two habitats revealed no consistent morphological dillerences. A similar comparison between P. pseudomilitaris and its nearest congener, I', potswaldi , indicated significant differences for 15 of 22 traits, although ranges overlapped for all bin two of these.     

Molecular and morphometric analyses identify new lineages within a large Eumida (Annelida) species complex

We report on two new lineages of the Eumida sanguinea complex from Great Britain and describe one of them as a new species using a multilocus approach, including the mitochondrial DNA COI-5P and the nuclear markers ITS (ITS1, 5.8S rRNA and ITS2) and 28S rRNA. The molecular analysis placed Eumida mackiei sp. nov. in a monophyletic clade with 19.1% (COI), 10.1% (ITS) and 1.7% (28S) mean distance to its nearest neighbour. Molecular diagnoses were also applied to nine lineages within the E. sanguinea complex. This was complemented with morphometric data employing multivariate statistical analysis and the incorporation of statistical dissimilarities against three other described species from the complex. Eumida mackiei sp. nov. can be distinguished from E. notata and E. maia by the larger distance between the eyes and differences in morphometric proportions mainly in the dorsal and ventral cirri as well as in the prostomial appendages. E. sanguinea sensu stricto failed to produce a cluster of its own in the morphometric analysis, probably due to juvenile bias. Integrative taxonomy provided strong evidence to formally describe a new cryptic species that can now be used in biomonitoring or other relevant ecological research.     

Population Dynamics of the Polychaetous Annelids of an Intertidal Habitat in Upper Old Tampa Bay,Florida

Following an extensive red-tide induced mass mortality of the benthic macrofauna of a sandy intertidal habitat, the population dynamics of the polychaete species were studied. Detailed studies of the 12 most abundant species are presented. Data concerning total population levels, reproduction, recruitment, distribution within the intertidal zone, and gut content analyses are integrated in order to explain the observed spatial and temporal patterns of distribution and abundance. Potential competive interactions for food are considered to be the most important factor for explaining the observed ecological patterns. The polychaete species studied are divided into three trophic guilds: an omnivorous guild that feeds predaciously and as non-selective deposit feeders, a surface feeding guild consisting of species usually considered to be selective surface deposit feeders, and a subsurface feeding guild usually considered as non-selective infaunal deposit feeders. Within and between guild interactions are discussed.