Caudal regeneration in Tubifex tubifex (Oligochaeta, Tubificidae) following copper exposure

Abstract. The oligochaete, Tubifex tubifex (Oligochaeta, Tubificidae), is capable of the auto-tomization and regeneration of missing body parts. The posterior end of the worm is subject to autotomy (e.g., after predation or after exposure to toxic substances) and can be regenerated thereafter. Despite the ecological importance of T. tubifex , processes of autotomy and regeneration have been little studied. This work describes daily morphological and histological observations of caudal regeneration of this worm. We also compared regeneration processes when autotomy was induced by artificial transsection of the worms (control worms) and by exposure to copper ion, a frequently encountered environmental contaminant. The worms regenerated a functional posterior end (defecation possible) in 7 d as well as a prepygidial zone from which new segments could be regenerated. In T. tubifex , regeneration involved the presence of activated mesoblastocytes in the worm, increased number of neoblasts, and the increased migration of these cells. However, Cu²⁺ did not affect these processes, since no difference could be detected between regeneration of control and Cu-autotomized worms.     

Interactions among two strains of Tubifex tubifex (Oligochaeta: Tubificidae) and Myxobolus cerebralis (Myxozoa)

Host-parasite interactions influence host population growth, host evolution and parasite success. We examined the interactions among Myxobolus cerebralis, the parasite that causes salmonid whirling disease, and resistant and susceptible strains of the oligochaete host Tubifex tubifex. Strains of T. tubifex with diverse genotypes often coexist in nature and have variable susceptibilities to M. cerebralis infection. Further, parasite proliferation differs by several orders of magnitude among T. tubifex strains. We examined total biomass produced by individual T. tubifex, including progeny production and adult growth, parasite proliferation and prevalence of infection using 2 strains of T. tubifex at 2 myxospore doses in a response-surface experimental design. Total biomass production per individual oligochaete and progeny biomass produced by an individual adult oligochaete were density-dependent for both resistant and susceptible individuals and the effects did not change with the addition of myxospores. However, both resistant and susceptible adults had highest growth when exposed to M. cerebralis. The presence of resistant oligochaetes in mixed cultures did not reduce the infection prevalence or parasite proliferation in susceptible individuals. In natural aquatic communities, resistant strains of T. tubifex may not reduce the effects of M. cerebralis on the salmonid host, particularly if sufficient numbers of susceptible T. tubifex are present.     

New records of Adelodrilus (Oligochaeta,Tubificidae), with descriptions of two new species from the North-west Atlantic

Adelodrilus fimbriatus sp.n. is described from bathyal depths off the continental shelf of Eastern United States, A. cristatus sp.n. from sublittoral bottoms on this shelf (off Maryland and New Jersey). The two species are principally distinguished from their congeners by the morphology of their penial setae. New geographical records and morphological notes are given for A. pusillus Erséus (including the first find of Adelodrilus in the Mediterranean Sea), A. cooki Erséus, A. voraginus (Cook), and A. acochlearis Erséus & Loden. A pictorial key to all eleven species of Adelodrilus is provided.     

Tubificidae (oligochaeta) from the Ross Sea (Antarctica), with descriptions of one new genus and two new species

Three species,Torodrilus gelidus sp. nov. (subfamily Rhyacodrilinae),Rossidrilus terraenovae gen. et sp. nov. (Limnodriloidinae), and a second unnamed species of Limnodriloidinae, are reported from marine sediments in Terra Nova Bay, Ross Sea. Torodrilus gelidus is distinguished fromT. lowryi Cook, 1970 by its setal pattern (with few exceptions, both anterior and posterior setae are single-pointed in sexually mature specimens ofT. gelidus) and the morphology of its male protuberances (the latter folded over a midventral bursa in segment XI).Rossidrilus terraenovae is characterized by large diverticula attached to the oesophagus in the posterior part of segment IX, unpaired male and spermathecal pores, heavily muscular and entally ciliated atrial ampullae, elongate prostatic pads, and a deep, unpaired and muscular, copulatory sac. It is the first species of its subfamily to be described from Antarctic waters.     

A new species of the subterranean genus Krenedrilus dumnicka (Oligochaeta, Tubificidae) from the deep bottom of an oligotrophic caldera lake in Japan

A new tubificid oligochaete, Krenedrilus towadensis, is described from deep bottoms of the oligotrophic caldera Lake Towada in northern Japan. It resembles K. realis Martínez-Ansemil and Collado, 1996, in the combination of somatic setae, but it is different from all other congeners by the lack of spermathecal setae and epidermal papillae in X, in the structures of penial and supernumerary setae, and in the location of spermathecal pores. The definition of Krenedrilus is revised.     

Marine Tubificidae (Oligochaeta) of Antarctica, with descriptions of three new species of Phallodrilinae

Five species of Tubificidae are recorded from Antarctic waters: Torodrilus lowryi Cook, 1970, Torodrilus sp. (subfamily Rhyacodrilinae), Marionidrilus antarcticus sp. n., M. weddellensis sp. n., and Thalassodrilus bicki sp. n. (subfamily Phallodrilinae); only T. lowryi was known from Antarctica before. The status of the two Southern Hemisphere genera Torodrilus Cook, 1970, and Marionidrilus Erséus, 1992, are discussed; although the taxonomic position of the two new species of Marionidrilus is somewhat uncertain. Thalassodrilus bicki , however, appears closely related to Northern Hemisphere taxa.     

Growth of Tubifex tubifex Müller (Oligochaeta,Tubificidae) under Various Trophic Conditions

Growth of Tubifex tubifex on highly caloric activated sludge and poor in organic matter natural silt was experimentally studied. The relationship between oxygen consumption rate, weight, and caloric value of T. tubifex body in culture on activated sludge was determined to calculate the growth efficiency (K₂ = P/P + R). The growth rate has been determined, and models of T. tubifex growth are given under various trophic conditions conforming to results of the experiment. Somatic growth, generative growth and life span of this species were compared on the basis of the experiments and literature. Acceleration of growth and prolongation of life under conditions of caloric food and delay of these processes in silt poor in organic matter have been established and measured. T. tubifex was found to have advantages as compared to other tubificid species in response to increasing amounts of nutrient food in waters polluted by organic matter and, therefore, to produce abundant populations under these conditions.     

Two new species of Hyalella from Lake Titicaca,and redescriptions of four others in the genus (Crustacea: Amphipoda)

The amphipod genus Hyalella has its highest diversity in the Andean Lake Titicaca. This genus is the only epigean amphipod present in South America. Eleven endemic and one non-endemic species are known from Lake Titicaca. An additional endemic species, Hyalella nefrens n. sp. and one non-endemic species Hyalella tiwanaku n. sp. are described here. Hyalella cuprea(Faxon, 1876), Hyalella latimanus (Faxon, 1876), Hyalella montforti Chevreux, 1907, and Hyalella neveulemairei Chevreux, 1904 are redescribed. The high diversity of Hyalella in the lake is not well understood, and it has been compared with the spectacular diversity of Lake Baikal.     

Six new species of marine Tubificidae (Oligochaeta) from the continental shelf off Peru

Six species of marine tubifieids are described from the continental shelf off Peru. Two of them are members of the gutless genus Olavius Erséus, 1984 (subfamily Phallodrilinae). Olavius bullatus sp.n. possesses 2 pairs of large penial setae in voluminous copulatory sacs, tiny atria, and spermathecal pores in line with dorsal setae. Olavius crassitunicatus sp.n. is characterized by small atria with thin muscular layer, spermathecae with short ducts, opening dorso-laterally, and lack of penial setae. Four species arc members of the subfamily Limnodriloidinae. Limnodriloides busilicus sp.n. belongs to the appendiculatus-group (sensu Erséus). It is discriminated by somatic setae with subdental ligaments, and its voluminous elongate prostatic pads. Limnodriloides clavellatus sp.n. is distinguished from its congeners by a peculiar bulge in the cavity of each atrial ampulla, and spermatozeugmata imbedded in the walls of the spermathecae. Tectidrilus intermixtus sp.n. is similar to T. bori (Righi & Kanner, 1979); it is distinguished from the latter by having trisetal bundles in segment V or V-VI and by lacking copulatory glands. Marcusaedrilus peruanus sp.n. is characterized by nongranulated atrial ducts and bipartite spermathecae.     

A generic revision of the Phallodrilinae (Oligochaeta, Tubificidae)

The generic classification of the subfamily Phallodrilinae (with a total of 252 species) is revised according to phylogenetic principles. Morphological character patterns are assessed under the principle of maximum parsimony, but due to the poor resolution and instability in the resulting cladograms, the analysis is supplemented with intuitive weighting of synapomorphic similarities. Thirty-one genera are recognized. The former definition of the type genus Phallodrilus Picrantoni, 1902, is revised and the members of this genus are reclassified into 20 taxa, each hypothesized to be monophyletic: Phallodrilus s.str . (revised to contain the type species only), Somalidrilus gcn.n., Milliganius gen.n., Phallodriloides gen.n., Albanidrilus gen.n., Abyssidrilus gen.n., Paraktedrilus gen.n., Uniporodrilus Erséus, 1979, Inermidrilus gen.n., Gianius gen.n., Mexidrilus gen.n., Peosidrilus Baker & Erséus, 1979, Atlantidrilus Erséus, 1983, Thalassodrilus Brinkhurst, 1963, Pirodrilus gen.n., Pirodriloides gen.n., Marionidrilus gen.n., Pectinodrilus gen.n., Pacifidrilus gen.n. and Pseudospiridion gen.n. Nine new species are described from the Northwest Atlantic: Phallodriloides pinnulatus sp.n., Abyssidrilus opulentus sp.n., A. potens sp.n., A. altoides sp.n., Mexidrilus obtusus sp.n., Peosidrilus dalei sp.n., P. aduncus sp.n., P. riseri sp.n., and Atlantidrilus hamulus sp.n. The genus Discordiprostatus Baker, 1982, is synonymized with Nootkadrilus Baker, 1982.     

What is Tubifex tubifex (O. F. Müller) (Oligochaeta,Tubificidae)?

A review of the fairly muddled conditions in the early history of Tubifex tubifex (O. F. Müller, 1774) is given. The identity of Müller's (1774) Lumbricus tubifex is discussed, analytical examinations of samples from the most likely type-locality of the species are accounted for, and a neo type has been selected. For comparison, other "Tubifex" specimens, both European and American, are likewise analysed and a scrutiny of the literature concerning the species and its synonyms is undertaken. The survey results in a clearer picture of T. tubifex and a revised view of the qualifying characters on the specific level. Diagnoses of the species T. tubifex (O. F. Müller) and T. fissidens sp.n., Kernall, MS, 1914, are given.     

A new earthworm species of the genus Drawida Michaelsen(Oligochaeta: Moniligastridae) from China

A new species of terrestrial earthworms is described as Drawida dandongensis sp. nov. from Dandong, Liaoning, China. It is distinguished from others by a pair of spermathecal pores lie in the ventral of 7/8 intersegmental furrow, and a pair of male pores lie in 10/11 intersegmental furrow, between setae b and c.     

A revision of Lycodrilus phreodriloides (Oligochaeta, Tubificidae)

The taxon Lycodrilusphreodriloides Michaelsen, 1905 is fully described for the first time. It is now recognized as Baikalodrilus phreodriloides (Michaelsen) comb.n., a member of the Tubificidae. This is the last of the original Lycodrilus species to be reclassified.     

A new diatom (Bacillariophyceae) genus with two new species from New Mexico,USA

A new diatom (Bacillariophyceae) genus and two new species are described from the arid region of the North American southwest. The new genus, Playaensis, and new species, P. circumfimbria and P. furtiva, are distinguished by frustule morphology and autecology. Playaensis possesses unique, narrowly lunate longitudinal ribs bordering the raphe and spathulate spines, but their evolutionary relationship to known genera is unclear. In Payton Lake, New Mexico, P. circumfimbria and P. furtiva are rare in the diatom community, and their geographic and geological extent are not known, but they may be restricted to alkaline, slightly saline lakes of the region.     

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.     

Environmental parameters and estivation of Rhyacodrilus (Tubificidae, Oligochaeta) in Lake Suwa, Japan

We confirmed that Rhyacodrilus spp of Yasuda and Okino (1987) (Tubificidae, Oligochaeta) migrated entirely downward below 15 cm into the sediment from June to September m Lake Suwa, a shallow eutrophic lake in Japan In October, Rhyacodrilus spp began to return to the upper layer and immediately attained sexual maturity They tended to show reduced body weight and respiratory activity during summer The results indicate that an oligochaete of Rhyacodrilus spp estivated in the deeper layer during summer The estivation ostensibly occurred at 15°C and the species died off at 20°C, so it is evident that they must migrate from the surface to the deeper layer of sediment during summer in order to escape high temperature Furthermore, physiological experiment suggested that this behavior is accelerated by low oxygen concentration with high temperature