Nais pseudobtusa Piguet, 1906 (Oligochaeta: Naididae) New to Australia

Nais pseudobtusa Piquet, 1906 is reported for the first time from Australia.     

Seasonal dynamics of aufwuchs Naididae (Oligochaeta) on Phragmites australis in a eutrophic lake

The Oligochaeta and Aphanoneura in the aufwuchs on Phragmites australis in a eutrophic hardwater lake were studied at two sites over a period of one year, in order to elucidate the structure and dynamics of this assemblage. The naidids Chaetogaster diastrophus, Nais spp., and Stylaria lacustris dominated the assemblage at any season. At both sites these taxa showed the same distinct pattern of successive population maxima in spring and summer: Chaetogaster diastrophus reached its peak density first, followed by Nais species, and eventually by Stylaria lacustris. Differences in temporal dynamics between sites were small apart from a second Stylaria maximum which was only observed at one site. Total naidid densities reached peak values of 3.8 individuals per cm² reed stem surface area. With mean individual biomass of 2.2 µg dry mass for Chaetogaster diastrophus, 13.3 µg for Nais, and 86 µg for Stylaria lacustris, respectively, maximum total naidid biomass on reed stems was 44 µg dry mass per cm². The biomass peak occurred later than that of total naidid density because in summer larger naidids dominated the assemblage. The observed succession appears to be consistent with seasonal changes in periphytic algal communities on the reed stems.     

Growth of Stylaria lacustris (L.) (Oligochaeta,Naididae)

The peculiarities of the growth in weight and length of Stylaria lacustris (L.) on the basis of observations in experimental vessels are considered. The growth of this species fits a parabolic curve. The equations relating weight to absolute growth rate as well as weight to duration of life are given.     

Seasonal dynamics of Bythonomus lemani and Bothrioneurum vejdovskyanum (Oligochaeta, Annelida) in relation to environmental variables

The seasonal dynamics of Bythonomus lemani (Lumbriculidae) were studied for the first time and the knowledge of Bothrioneurum vejdovskyanum (Tubificidae) was extended based on four quantitative samples of oligochaetes taken monthly in the Rokytná River (Czech Republic) during a two-year study (April 1999–April 2001). The influence of water temperature, velocity, depth, discharge, pH, conductivity, dissolved oxygen amount and biochemical oxygen demand (BOD) on their life cycles was evaluated. Habitat preferences of the juvenile and adult stages were recorded. Time series analysis was used to determine the worm densities, seasonality and trends. For Byth. lemani one distinct reproduction cycle per year was found and this was regulated by temperature, while Both. vejdovskyanum showed a one-year cycle not significantly dependent on measured environmental variables. The overall trend was an increase in density for Byth. lemani and a decrease in density for Both. vejdovskyanum. Byth. lemani showed a significant negative correlation between the trend of its density and BOD concentration.     

The geographical distribution of Naididae (Oligochaeta) in Britain

A compilation of records of the geographical location of naidid species in Britain is presented. Many species previously considered rare are shown to be widely distributed.     

Specific criteria in Grania (Oligochaeta,Enchytraeidae)

The structure of the penial bulb and male efferent duct system of Grania species may be used in addition to setal pattern and spermathecal shape to distinguish species. Six penial bulb types are distinguished: (1) a simple, small, glandular bulb surrounding the male pore; (2) a small, glandular bulb, with a large, associated, dorso-medial gland mass; (3) a small glandular bulb, medial to the male pore, with an elongate male bursa (the aglandular sac), the vas deferens exitting directly into the invaginated male pore; (4) a glandular bulb with an aglandular sac and a small, cuticular stylet embedded in the bulb, extending from the ectal end of the vas deferens; (5) a glandular bulb and an aglandular sac with a long stylet extending from the vas deferens, through the bulb into the sac; and (6) glandular bulb reduced or absent, with or without an aglandular sac; with a long stylet and other prominent modifications, usually muscular, of the vas deferens. The details of the male duct structure were consistent within specimens grouped on the basis of setal distribution and shape and detailed spermathecal structure. Diverse male duct patterns are found within the polytypic species G. macrochaeta and G. postclitellochaeta. The positions of the spermathecal and male pores in their respective segments are distinctive for some species.     

A note on the nutrition of Stylaria lacustris (Oligochaeta: Naididae)

Stylaria lacustris (L.) was offered ¹⁴C-labelled algae. The ingestion rate of diatoms was 0.79 g carbon/hour at 19°C. Diatoms (Nitzschia actinastroides) were well assimilated, green algae (Scenedesmus acuminatus) were practically not assimilated. The less assimilable algae are ingested at higher rates, indicating a regulation mechanism. Biomass doubling time was estimated to be about 3.6 days at 19°C.     

A note on the feeding ofAmphichaeta leydigii (Oligochaeta,Naididae) in lacustrine sandy shores

The analysis of gut contents ofAmphichaeta leydigii, found for the first time in Italy in sandy shores of Lake Vico (Central Italy), proved grazing of the species on diatoms (Centrales and Pennales). Detritus and organic particles, abundant in the substratum, were observed only in small amounts.     

The selection and ingestion of epilithic algae byNais elinguis (Oligochaeta: Naididae)

The gut contents ofNais elinguis in an organically polluted river were dominated by epilithic chlorophycean unicells and pennate diatoms with an average cell volume of 1.3 × 10³ µm³. The worm unselectively and opportunistically ingested unicellular algae up to a maximum length of 196 µm and a maximum volume of 24 × 10³ µm³, but colonial and filamentous algae were discriminated against. The morphometry of the pharynx ofN. elinguis probably determined the maximum size of algal cells which could be ingested.     

New species of Phallodrilus (Oligochaeta,Tubificidae) from caves of northern Spain and southwestern France

A taxonomic account of a collection of Phallodrilus species inhabiting caves is given. The following three new species are described: P. subterraneus, P. crypticus and P. labouichensis. New material of P. aquaedulcis Hrabe, 1960 from northern Spain and southwestern France is reported. This species was previously known from West Germany. The relationship between Phallodrilus cave species and littoral and deep-sea species is discussed.     

Contributions towards the taxonomy of the African Naididae (Oligochaeta). IV. Zoogeographical and taxonomical considerations on African Naididae

A systematic revision of African Naididae confirmed the presence of 16 genera and 48 species. Allonais ranauana Boldt, 1932 is confirmed as a distinct species, Nais raviensis Stephenson, 1914 has very short gills and is a species of Dero, and Rhopalonais has equally obscure gills and is attributable to Dero. Pristina proboscidea Beddard, 1896 is synonymous with P. longiseta Ehrenberg, 1828.African naidids are primarily tropical, the most widespread genus is Pristina, followed by Aulophorus, Nais and Dero. Nais is dominant in South Africa, whereas the other genera predominate in the tropics along with Rhopalonais. The most widespread species are A. furcatus, N. variabilis, P. longiseta and P. menoni.Serrations on hair setae and intermediate teeth in bifid needles are universally present as seen under SEM, their reported absence under light microscopes is attributable to lack of resolution power. SEM is also useful in determining gills in Dero. Size of setae within and between individuals is more constant than the literature would suggest as the standard deviation is usually less than 10% of the mean. There is a constant relationship between setal length and size of worm, and between median ventral setae and needles in this material.Setal size is a diagnostic character in taxonomy. The standard deviation of the mean number of segments in front of the budding zone averages 9.9%, the highest value (25.7%) was for Stylaria fossularis. Differences of more than 10% may usually be considered diagnostic. The total number of segments is exceedingly variable and cannot be used as a taxonomical characteristic. The same applies to segment length or diameter.     

Population dynamics of Stylaria lacustris (Linnaeus, 1767) (Oligochaeta,Naididae) in Los Talas,Argentina

Population dynamics of Stylaria lacustris were analyzed over 2 years in a pond located at Los Talas, Argentina. In both years, the peak in abundance, due to intense asexual reproduction, fell at the end of winter, and was followed by mature individuals. The species was not collected during summer. Temperature was the main factor regulating the population through both sexual and asexual reproduction. In the second year, density was lower and correlated with a lower water level and a reduced vegetation development. Individuals were randomly distributed in periods of high abundance and contagious when density was low. Generation time was 15 days.     

Feeding habits and dietary overlap of Naididae (Oligochaeta) from a bog stream

Feeding habits and dietary overlap of three species of naidid oligochaetes (Chaetogaster diastrophus, Dero digitata, Dero nivea) were studied during June 1982–December 1983 from a bog stream in Wisconsin, USA. Chaetogaster diastrophus primarily ingested diatoms, while D. digitata and D. nivea primarily ingested detritus. Dietary overlap was substantial (97–98%) between D. digitata and D. nivea using the dietary overlap coefficient. Dietary overlap between C. diastrophus and D. digitata was 58–62% and that between C. diastrophus and D. nivea was 51–55%. Dietary differences existed between the three species in the percentage of each major food type and diatom genera ingested, selective ingestion or avoidance of diatom genera and in the size classes (length and/or volume) of diatoms consumed. These data suggest temporal coexistence of these species may possibly be due to complex food resource partitioning, although in this habitat, C. diastrophus, D. digitata, and D. nivea did not exhibit concurrent peak abundances; thus, interspecific competition for food was minimized.     

Immunocytochemical demonstration of vertebrate neuropeptides in the earthworm Lumbricus terrestris (Annelida,Oligochaeta)

Summary The localisation and distribution of 10 vertebrate-derived neuropeptides in the earthworm, Lumbricus terrestris, have been determined by an indirect immunofluorescence technique. The peptides are pancreatic polypeptide (PP), peptide tyrosine tyrosine (PYY), neuropeptide Y (NPY), glucagon (C-terminal), vasoactive intestinal polypeptide (VIP), peptide histidine isoleucine (PHI), gastrinreleasing peptide (GRP), calcitonin gene-related peptide (CGRP), neurotensin (NT), and met-enkephalin. For 6 of the peptides — PYY, NPY, PHI, glucagon, GRP and CGRP — this is the first demonstration of their presence in any annelid, and NT has not previously been described in an oligochaete. Cell bodies and nerve fibres immunoreactive to the 10 peptides occur throughout the CNS. In the PNS, epidermal sensory cells displayed immunoreactivities to PP and PYY, and PP-, PYY-, NPY-, PHI- and GRP-like immunoreactivities occurred in nerve fibres supplying the main body muscles. Nerve fibres immunoreactive to PP and PYY are also associated with the innervation of the gut (pharynx, oesophageal glands, and mid and posterior regions of the intestine). No endocrine cells immunoreactive for any of the antisera tested could be identified in the gut epithelium, suggesting that dual location of peptides in the brain and gut epithelium is a phenomenon that occurred at a later stage in evolution. No immunoreactive elements were detected in any of the organs and ducts of the reproductive and excretory systems.     

Method for distinguishingLimnodrilus hoffmeisteri andLimnodrilus claparedeianus (Oligochaeta,Tubificidae) and its applicability in Lake Suwa

It is still next to impossible to distinguish species using immature worms of theLimnodrilus genus. A method was developed to separate mixed immature populations ofLimnodrilus hoffmeisteri andLimnodrilus claparedeianus into each species. The ratio of setal upper tooth length to lower tooth length, inL. hoffmeisteri andL. claparedeianus, ranged from 0.9 to 1.6 and from 1.3 to 2.1, respectively. Even if the median value of the frequency overlapped, this indistinguishable portion did not exceed 6% of each population.     

Ecology of Naididae (Oligochaeta) from an alkaline bog stream: life history patterns and community structure

Population and community dynamics of naidid oligochaetes were studied from June 1982–December 1983 in a sluggish, alkaline bog stream situated within Cedarburg Bog, Ozaukee County, Wisconsin, USA. Temporal differences in periods of peak abundance were observed for five species studied in detail: Chaetogaster diaphanus (mid-August and September), Chaetogaster diastrophus (mid-May), Dero digitata (mid-September), Dero nivea (mid-October), and Pristina leidyi (mid-October). Several correlations of abiotic and biotic parameters to density and percentage of naidids reproducing asexually were calculated. Mean doubling times (days) for field populations were 12.1, 22.7, 62.4, 19.6, 27.7 for C. diaphanus, C. diastrophus, D. digitata, D. nivea, and P. leidyi, respectively. Asexual reproduction by paratomy was the principal method of population increase. Sexual specimens were observed for Stylaria lacustris during June and October–December, D. digitata in September, C. diastrophus and Nais simplex during October, and C. diaphanus in October–November. Generally, a high proportion of the respective population was sexually mature when this type of reproduction occurred. Naididae community diversity index values using the Shannon-Weaver index ranged from 0.19–3.86.     

Two aberrant Tubificidae (Oligochaeta) from Pearl River in the People's Republic of China

The enigmaticIlyodrilus mastix Brinkhurst, 1978, andTectidrilus achaetus sp.nov. are described from the Guangzhou Reach of Pearl River, southern China. The first species is characterized by its greatly enlarged, eversible, feeding apparatus, and was previously known only from British Columbia, Canada.Tectidrilus achaetus is unique within the Tubificidae by lacking setae. A slightly modified definition of the, otherwise marine, genusTectidrilus Erséus, 1982 is provided.     

A choice chamber experiment on the selection of algae as food and substrata by Nais elinguis (Oligochaeta: Naididae)

SUMMARY.

• 1 A choice chamber experiment was performed in the laboratory to quantify the selection of benthic algae as food and substrata by Nais elinguis.
• 2 Most worms actively chose filamentous algae and/or diatoms as substrata whereas unicellular or colonial chiorophycean algae were discriminated against. Diatoms were selected in preference to latex beads but the worms could not discriminate between living filaments and nylon monofilaments. A thigmotactic response to filaments and a chemotactic response to diatoms may be implicated.
• 3 The worms ingested unicellular algae at a greater rate than colonial and filamentous algae. The rates at which the algae were ingested were negatively correlated with the lengths of the algae. A filament 200 μm long was the largest item ingested, representing about 63% of the length of the pharynx of the worm.
• 4 Ivlev's electlvity indices were positive when the rates at which the algae were ingested exceeded about 20 individuals h^-1. The index was negatively correlated with the lengths of the algae, but the time periods spent by the worms in association with the algae were unrelated to the electivity index.
• 5 The data confirmed previous observations on the selection of algae as food and substrata by Nais elinguis in a natural habitat.