Lateral Row Research Articles

On the associations between Haplosyllis (Polychaeta, Syllidae) and gorgonians (Cnidaria, Octocorallaria), with the description of a new species

The present paper includes a morphological, ecological and biological updating of the three gorgonian associated species of Haplosyllis (Polychaeta, Syllidae) known to date: H. chamaeleon (symbiont with Paramuricea clavata in the Mediterranean), H. anthogorgicola (symbiont with Anthogorgia bocki in the Japanese seas) and H. villogorgicola , a new species living symbiotically with Villogorgia bebrycoides which is only known from Tenerife (Canary Islands, Eastern Central Atlantic). The new species is described on the basis of ecological, morphological, morphometric and statistical analysis of relevant characteristics. Each host colony harboured about 15 pale-yellowish worms, whose cryptic colouration mimicked that of the host. They occurred either on the host branches or partly hidden inside cavities formed by the fusion of two branches. The new species is characterized by the presence of simple chaetae with clearly bidentate tips all along the body, the presence of gland pore aggregates distributed in two lateral rows and two ventral patches on each palp and the absence of ciliary tufts on the pharyngeal papillae. H. villogorgicola sp. nov. is closely related to H. chamaeleon . Thus, it is compared with two populations of this species collected in the north-west and south-west Mediterranean. Stolons of H. chamaeleon are re-described as tetracerous and a peculiar posterior end regeneration process occurring in adult worms during the stolon formation is described. H. anthogorgicola is also re-described, with particular emphasis on its appendage and chaetal arrangements. The main features of the three associations are discussed in light of the current knowledge on symbiotic polychaetes, particularly cnidarian-associated syllids. © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 77 , 455‐477. ADDITIONAL KEYWORDS: adaptation ‐ Annelida ‐ ecology ‐ gorgonian ‐ Polychaeta ‐ reproduction ‐ symbiosis ‐ taxonomy.

Ciliary filter‐feeding structures in adult and larval gymnolaemate bryozoans

Abstract. Ciliary filter‐feeding structures of gymnolaemate bryozoans—adults of Flustrellidra hispida and Alcyonidium gelatinosum, larvae of Membranipora sp.—were studied with SEM. In F. hispida and A. gelatinosum, the distal part of each tentacle has a straight row of stiff laterofrontal cilia which carry out “ciliary sieving” to capture suspended food particles that are subsequently transported downward towards the mouth by tentacle flicking; both structure and function resemble those of stenolaemate tentacles. The proximal part of the tentacle and of the ciliary ridge of a cyphonautes larva have strikingly similar structures, except that the laterofrontal cells are monociliate in the adults and biciliate in the larvae. The laterofrontal cells of the tentacles are arranged in a zigzag row and their cilia form two parallel rows, a frontal and a lateral row. The latter probably forms the sieve of stiff filter cilia in front of the water‐pumping lateral cilia, whereas the frontal row appears to be held close to the frontal ciliary band of the tentacle. The biciliate laterofrontal cells of the cyphonautes larva have the cilia arranged in similar rows. The detailed morphological similarities between the ciliary bands of adult and larval filtering structures suggest that the feeding mechanisms are similar, contrary to what has been previously thought.

Perforator topography of the deep inferior epigastric perforator flap in 100 cases of breast reconstruction.

The anatomic topography of the perforators within the rectus muscle and the anterior fascia largely determines the time needed to harvest the perforator free flap and the difficulty of the procedure. In 100 consecutive cases, the topographic patterns of the perforators were investigated. In 65 percent, a short intramuscular course was seen. In 16 percent, a perforator at the tendinous intersection was encountered. In 9 percent, the largest perforator was found to have a long intramuscular course. In 5 percent, a subfascial course was found, and in another 5 percent, a paramedian course was found. In 74 percent of flaps, just one perforator was used, whereas two perforators were dissected in 20 percent. Only in 6 percent of flaps were three perforators used. A long intramuscular course (>4 cm) lengthens the dissection substantially, especially when the intramuscular course is in a step-wise pattern. The subfascial course requires precarious attention at the early stage of the perforator dissection when splitting the fascia. The perforators at the tendinous intersections are the most accessible and require a short but intense dissection in the fibrotic tissue of intersection. A paramedian perforator, medial to the rectus muscle, is a septocutaneous rather than a musculocutaneous perforator. The straightforward dissection almost extends up to the midline. Therefore, dissection always is performed at one side and, if no good perforators are present, continued at the intact contralateral side. The size of these perforators and their location in the flap determine the choice. One perforator with significant flow can perfuse the whole flap. If in doubt, two perforators can be harvested, especially if they show a linear anatomy so that muscle fibers can be split. The only interference with the muscle exists in splitting the muscle fibers. A perforator that lies in the middle of the flap is preferable. For a large flap, a perforator of the medial row provides better perfusion to zone 4 than one of the lateral row because of the extra choke vessel for the lateral row perforators. The clinical appearance of the perforators is the key element in the dissection of the perforator flap. Perforator topography determines the overall length and difficulty of the procedure.

Odontobutis hikimius n. sp.: A New Freshwater Goby from Japan, with a Key to Species of the Genus

The freshwater goby, Odontobutis hikimius n. sp., is described based on specimens collected from Shimane Prefecture, Japan. The species is unique among Odontobutis in having a connection between the transverse and longitudinal sensory papillae rows on the opercle. It is also distinguishable from congeners by the following combination of characteristics: only a short sensory canal present posterodorsally to eye, lateral scale rows 38–49. Diagnosis of the genus Odontobutis is revised and a key to the seven known species is provided.

Dental homologies in lamniform sharks (Chondrichthyes: Elasmobranchii).

The dentitions of lamniform sharks are said to exhibit a unique heterodonty called the "lamnoid tooth pattern." The presence of an inflated hollow "dental bulla" on each jaw cartilage allows the recognition of homologous teeth across most modern macrophagous lamniforms based on topographic correspondence through the "similarity test." In most macrophagous lamniforms, three tooth rows are supported by the upper dental bulla: two rows of large anterior teeth followed by a row of small intermediate teeth. The lower tooth row occluding between the two rows of upper anterior teeth is the first lower anterior tooth row. Like the first and second lower anterior tooth rows, the third lower tooth row is supported by the dental bulla and may be called the first lower intermediate tooth row. The lower intermediate tooth row occludes between the first and second upper lateral tooth rows situated distal to the upper dental bulla, and the rest of the upper and lower tooth rows, all called lateral tooth rows, occlude alternately. Tooth symmetry cannot be used to identify their dental homology. The presence of dental bullae can be regarded as a synapomorphy of Lamniformes and this character is more definable than the "lamnoid tooth pattern." The formation of the tooth pattern appears to be related to the evolution of dental bullae. This study constitutes the first demonstration of supraspecific tooth-to-tooth dental homologies in nonmammalian vertebrates.

The central nervous system, its cellular organisation and development, in the tadpole larva of the ascidian Ciona intestinalis

From its numerical composition, the central nervous system (CNS) of the ascidian larva is one of the simplest known nervous systems having a chordate plan. Fewer than 350 cells together constitute a caudal nerve cord, an interposed visceral ganglion containing motor circuits for swimming and, rostrally, an expanded sensory vesicle containing major sensory and interneuron regions of the CNS. Some cells are ependymal, with ciliated surfaces lining the neural canal, while others are clearly either sensory receptors or motoneurons, but most are distinguishable only on cytological grounds. Although reassignments between categories are still being made, there is evidence for determinancy of total cell number. We have made three-dimensional cell maps either from serial semithin sections, or from confocal image stacks of whole-mounted embryos and larvae stained with nuclear markers. Comparisons between the maps of neural tubes in embryos of successive ages, that is, between cells in one map and their progeny in older maps, enable us to follow the line of mitotic descent through successive maps, at least for the caudal neural tube. Details are clear for the lateral cell rows in the neural tube, at least until the latter contains approximately 320 cells, and somewhat for the dorsal cell row, but the ventral row is more complex. In the hatched larva, serial-EM reconstructions of the visceral ganglion reveal two ventrolateral fibre bundles at the caudalmost end, each of 10-12 axons. These tracts include at least five pairs of presumed motor axons running into the caudal nerve cord. Two pairs of axons decussate. Complementing this vertebrate feature in the CNS of the larval form of Ciona, we confirm that synapses form upon the somata and dendrites of its neurons, and that its motor tracts are ventral.

Heterochrony and tooth evolution in hyperodapedontine rhynchosaurs (Reptilia, Diapsida)

The tooth arrangement of hyperodapedontine rhynchosaurs shows clear patterns of morphological derivation, which can be summarized as three main apomorphic trends: the increase in the number of tooth rows lateral to the main maxillary groove, the loss of dental structures (medial groove and lingual teeth) medial to the main maxillary groove, and the loss of dental structures (medial crest and lingual teeth) medial to the main dentary crest. The analysis of these trends from a heterochronic viewpoint reveals that acceleration was the most probable process involved in the increase in number of the lateral maxillary tooth rows, while the loss of the medial structures of the maxilla and dentary seem to be related respectively to neoteny and post-displacement. Both peramorphic and paedomorphic processes are, therefore, thought to have directed the main modifications seen in the tooth arrangement of the hyperodapedontine rhynchosaurs. Heterochrony plays an important role in the evolution of the Late Triassic rhynchosaurs, which are differentiated mainly on the basis of their dental morphology.

Acanthodian fish remains from the Lower Devonian Cavan Bluff Limestone (Murrumbidgee Group), Taemas district, New South Wales

A well-preserved acanthodian fish fauna from the Lower Devonian (early Emsian) Cavan Bluff Limestone (Murrumbidgee Group), Taemas, Yass district, New South Wales, consists of dentigerous jawbones, fin spines and scales. Four taxa belonging to the Order Ischnacanthida are recognized including Taemasacanthus erroli Long, 1986 and newly described genera and species Cavanacanthus warrooensis gen. et sp. nov., Cambaracanthus goodhopensis gen. et sp. nov. and Taemasacanthus porca sp. nov. An amended diagnosis is provided for T. erroli. The jawbone of C. warrooensis gen. et sp. nov. is of moderate size and bears a single row of teeth with a circular parabasal section. The jawbone extends in an anterior direction beyond the foremost tooth. C. goodhopensis gen. et sp. nov. is a small to moderate sized jawbone bearing two teeth rows separated by a longitudinal ridge. The teeth of the mesial tooth row, the main tooth row, are circular in parabasal section. The lateral tooth row is weakly developed, bearing one or two incipient teeth. T. porca sp. nov. is represented by a small curved jawbone (mesially concave) bearing two teeth rows separated by a prominent longitudinal ridge. The teeth of both tooth rows have a circular parabasal section. The anterior extension of this ridge beyond the foremost tooth represents approximately one quarter the length of the jawbone. These fishes inhabited a Lower Devonian carbonate platform consisting of patch reefs built upon a muddy substrate on a low energy shallow marine shelf which was subjected to frequent storm surges.

Scanning electron microscopy of newly excysted juvenile and adult Cyclocoelum mutabile (Digenea)

In this study, changes were examined in surface structures and tegumental morphology of newly excysted, migrating, and adult Cyclocoelum mutabile obtained from experimentally infected coots (Fulica americana). Newly excysted juveniles were spinous and had two large depressions situated at the anterior tip of the body and a large acetabulum. Small papillae were scattered around the mouth region and also formed a row that encircled the anterior end of the fluke. Four groups of larger papillae, two ventrolateral and two lateral, originated from points slightly posterior to the mouth region. The two ventrolateral bands of papillae terminated slightly posterior to the acetabulum; the two lateral rows of papillae terminated about three-quarters of the length along the specimen. Six large multilobed papillae were associated with the acetabulum. Juveniles migrating through the liver lost the spines and papillae by day 6, but the anterior depressions persisted into the adult stage. The tegument of 6- and 12-day-old flukes was smooth with a varying number of transverse folds. The tegument of 15-day-old specimens from the body cavity ranged in appearance from folded and pitted to reticulate. The reticulations were more prominent in adults and the entire body was covered with a reticulate pattern of loculus-like structures that are believed to aid in the movement of the flukes within the air sacs of the coot host.

The nonmuscle myosin regulatory light chain gene mlc-4 is required for cytokinesis, anterior-posterior polarity, and body morphology during Caenorhabditis elegans embryogenesis.

Using RNA-mediated genetic interference in a phenotypic screen, we identified a conserved nonmuscle myosin II regulatory light chain gene in Caenorhabditis elegans, which we name mlc-4. Maternally supplied mlc-4 function is required for cytokinesis during both meiosis and mitosis and for establishment of anterior-posterior (a-p) asymmetries after fertilization. Reducing the function of mlc-4 or nmy-2, a nonmuscle myosin II gene, also leads to a loss of polarized cytoplasmic flow in the C. elegans zygote, supporting models in which cytoplasmic flow may be required to establish a-p differences. Germline P granule localization at the time of cytoplasmic flow is also lost in these embryos, although P granules do become localized to the posterior pole after the first mitosis. This result suggests that a mechanism other than cytoplasmic flow or mlc-4/nmy-2 activity can generate some a-p asymmetries in the C. elegans zygote. By isolating a deletion allele, we show that removing zygotic mlc-4 function results in an elongation phenotype during embryogenesis. An mlc-4/green fluorescent protein transgene is expressed in lateral rows of hypodermal cells and these cells fail to properly change shape in mlc-4 mutant animals during elongation.

Scanning electron microscopy of newly excysted juvenile and adult <i>Cyclocoelum mutabile</i> (Digenea)

In this study, changes were examined in surface structures and tegumental morphology of newly excysted, migrating, and adult Cyclocoelum mutabile obtained from experimentally infected coots (Fulica americana). Newly excysted juveniles were spinous and had two large depressions situated at the anterior tip of the body and a large acetabulum. Small papillae were scattered around the mouth region and also formed a row that encircled the anterior end of the fluke. Four groups of larger papillae, two ventrolateral and two lateral, originated from points slightly posterior to the mouth region. The two ventrolateral bands of papillae terminated slightly posterior to the acetabulum; the two lateral rows of papillae terminated about three-quarters of the length along the specimen. Six large multilobed papillae were associated with the acetabulum. Juveniles migrating through the liver lost the spines and papillae by day 6, but the anterior depressions persisted into the adult stage. The tegument of 6- and 12-day-old flukes was smooth with a varying number of transverse folds. The tegument of 15-day-old specimens from the body cavity ranged in appearance from folded and pitted to reticulate. The reticulations were more prominent in adults and the entire body was covered with a reticulate pattern of loculus-like structures that are believed to aid in the movement of the flukes within the air sacs of the coot host.

Characteristics of spermiogenesis and mature spermatozoa in Gyratrix hermaphroditus (Plathelminthes, Rhabdocoela, Kalyptorhynchia)

Some events of spermiogenesis and the submicroscopic anatomy of male gametes in Gyratrix hermaphroditus are described. Special features occurring during the steps of sperm cell maturation are the development of delicate rootlet-like and spike-shaped structures attached to the basal bodies, an anchor apparatus of cilia staying near the tip of the outgrowing spermatids, the differentiation of a single mitochondrial rod, and the processes of compartmentalizing the chromatin resulting in the formation of extranuclear lamellar stacks. Mature spermatozoa are especially characterized by two incorporated axonemes, a string of large mushroom-shaped dense bodies in the anterior section of the cell, and two lateral rows of nuclear lamellar stacks in the median cell segment. Based on the present findings, the process of spermiogenesis and the organization of spermatozoa in the ground pattern of the monophylum Kalyptorhynchia are reconstructed. Apparently, the sister group of the Kalyptorhynchia can be found within the other free-living and symbiotic Rhabdocoela; the hypothesis of a sister group relationship with the Neodermata is not corroborated. Probably, spermatozoal characteristics can contribute to a discrimination between distinct populations of G. hermaphroditus which is proved to be a complex of several sibling species.

Structure of the ovipositor, associated sensilla and spermathecal system of entomoparasitic pipunculid flies (Diptera Pipunculidae)

The external parts of the female reproductive system in entomoparasitic flies of the family Pipunculidae form a compact, heavily sclerotized ovipositor for inserting the egg into the host. Two types of pipunculid ovipositor have been recognized: The Nephrocerus type is bilaterally asymmetrical and consists of modified abdominal segments 8 and 9. There is no spiracle. The genital opening is situate ventrally, approximately in the middle of the ovipositor. The Pipunculus type ovipositor is bilaterally symmetrical and originates from abdominal segments 7, 8 and 9. A pair of spiracles are located venterolaterally near the basal margin; the genital opening is situated close to the apex. Two types of campaniform and two types of haired sensilla have been found (tergum 9 only). Campaniform sensilla have been observed in apical third to apical half of the ovipositor of all studied species. Ten long haired sensilla arranged in two lateral rows on apex have been recognized only in species of Nephrocerus. Short haired sensilla have been found in all Chalarinae and Pipunculinae, situated in basal half of the ovipositor piercer. The spermathecal system consists of three spermathecae; well sclerotized (Nephrocerinae, Chalarinae) or soft and membraneous (Pipunculinae); and three spermiducts which can be undifferentiated and tubular (Nephrocerus) or differentiated to muscular, glandular and ductal parts (Chalarinae, Pipunculinae). In the Nephrocerus type ovipositor, spermathecae are situated in the distal half of abdominal segment 6; all other Pipunculidae have spermathecae located in the basal part of the ovipositor.

Limnomermis subtropicalis n. sp. (Nematoda:Mermithidae) a parasite of larvae of Simulium orbitale Lutz (Diptera:Simuliidae) in Argentina.

Limnomermis subtropicalis n. sp. (Nematoda:Mermithidae) a parasite of Simulium orbitale Lutz (Diptera:Simuliidae) found in Argentina is described and illustrated. This species is characterized by having medium sized amphids, pocket-shaped, medium sized vagina, sculptured spicule, and by having 9 preanal, 7 postanal papillae in the ventral row, and 12 papillae in the lateral rows.

Ultrastructure of the labrum and foregut of Derocheilocaris remanei (Crustacea, Mystacocarida).

The cuticle-lined foregut of Derocheilocaris remanei consists of the mouth with its associated labrum, and an undifferentiated esophagus. It is separated from the midgut by an esophageal valve. The labrum is a conspicuous structure moved by five pairs of muscles (four dorsoventral and one longitudinal). Four pairs of subcuticular glands open to its inner face forming two longitudinal, lateral rows of cuticular pores. Each secretory unit is composed of a glandular component (with one or two secretory cells), a neck cell, and a duct cell. In addition, a single gland cell opens mesially into the buccal cavity. The ventrally located mouth is a complex structure characterized by a filter-like system, a sensory organ, and epithelial cells with highly developed microvilli. The esophagus is a simple tube with a characteristic curvature following the mouth. It has a rounded cross section and a triradiate lumen. A layer of circular musculature surrounds this region. The end of the esophagus protrudes into the midgut lumen forming the so-called esophageal valve. The ultrastructural features of the foregut, with the presence of a mucus-trapping mechanism, a relatively well-developed filter system and associated structures and an esophagus lacking glands confirm the microphagic feeding habits of mystacocarids. © 1996 Wiley-Liss, Inc.

Msh may play a conserved role in dorsoventral patterning of the neuroectoderm and mesoderm

Many of the mechanisms that govern the patterning of the Drosophila neuroectoderm and mesoderm are still unknown. Here we report the sequence, expression, and regulation of the homeoɡ gene msh, which is likely to play an important role in the early patterning events of these two tissue primordia.msh expression is first observed in late blastoderm embryos and occurs in longitudinal bands of cells that are fated to become lateral neuroectoderm. This expression is under the control of dorsoventral axis-determination genes and depends on dpp-mediated repression in the dorsal half of the embryo and on flb-(EGF-) mediated repression ventrally. The bands of msh expression define the cells that will form the lateral columns of proneural gene expression and give rise to the lateral row of SI neuroblasts. This suggests that msh may be one of the upstream regulators of the achaete-scute (AS-C) genes and may play a role that is analogous to that of the homeoɡ gene vnd/NK2 in the medial sector of the neuroectoderm. During neuroblast segregation, msh expression is maintained in a subset of neuroblasts, indicating that msh, like vnd/NK2, could function in both dorsoventral patterning of the neuroectoderm and neuroblast specification. The later phase of msh expression that occurs after the first wave of neuroblast segregation in defined ectodermal and mesodermal clusters of cells points to similar roles of msh in patterning and cell fate specification of the peripheral nervous system, dorsal musculature, and the fat body. A comparison of the expression patterns of the vertebrate homologs of msh, vndNK2, and AS-C genes reveals striking similarities in dorsoventral patterning of the Drosophila and vertebrate neuroectoderm and indicates that genetic circuitries in neural patterning are evolutionarily conserved.

Peanut Response to Prohexadione Calcium, a New Plant Growth Regulator

Abstract Experiments in 1992, 1993, and 1994 evaluated prohexadione calcium (calcium salt of 3,5-dioxo-4-propionylcyclohexanecarboxylic acid) as a growth regulator for peanut (Arachis hypogaea L.). Two experiments in 1992 compared prohexadione calcium applied at 140 to 560 g ae/ha at the early pegging stage (PG) or at the row closure stage (RC). Greater suppression of main stem (MS) and cotyledonary lateral branch (CLB) length and greater row visibility at harvest were noted when prohexadione calcium was applied at RC. Prohexadione calcium applied at RC decreased MS and CLB length at harvest 16 to 27% and 14 to 29%, respectively, and greatly improved row visibility. Prohexadione calcium applied at PG generally reduced yield and the percentage of extra large kernels (ELK), fancy pods (FP), and total sound mature kernels (TSMK) but had no effect on crop maturity. Prohexadione calcium applied at RC generally had no effect on yield or the proportion of TSMK but increased the percentage of ELK, decreased the percentage of FP, and enhanced crop maturity. Two experiments in 1993 compared prohexadione calcium at rates of 47 to 280 g/ha applied at RC or at RC and again 3 wk later (RC3). Prohexadione calcium at 140 and 280 g/ha applied at RC suppressed MS and CLB length at harvest 11 to 18% and improved row visibility. Single and sequential applications were equally effective. Prohexadione calcium had no effect on yield, maturity, or the percentage of ELK, FP, and TSMK in 1993. One experiment in 1994 compared prohexadione calcium at rates of 186 to 280 g/ha applied at RC and RC3 or at RC and RC3 and 6 wk after RC (RC6). Results were similar with all treatments. MS and CLB length at harvest was reduced 29 to 34% and 28 to 32%, respectively, and row visibility was greatly improved. Prohexadione calcium increased yield 8% and increased the percentage of ELK but had no effect on the percentage of FP and TSMK. Daminozide [butanedioic acid mono (2,2-dimethylhydrazide)] at 950 to 1430 g ae/ha was included in all experiments as a comparison. Row visibility and suppression of MS and CLB length at harvest in prohexadione calcium-treated peanut were at least as great as in daminozide-treated peanut. Results indicate prohexadione calcium could be an effective-replacement for daminozide.

Postglacial evolution in lateral plate morphs in Norwegian freshwater populations of the threespine stickleback (Gasterosteus aculeatus)

Norwegian freshwater stickleback populations were founded after the last glacial period, and the progressive uplift of the land has produced an age range (1000 – 13 000 years) of the stickleback habitats. Most of the freshwater populations of today have probably been formed by isolation of marine sticklebacks in the process of land uplift. The freshwater threespine stickleback is known for its great morphological variability. Three distinct morphs ("low," "partial," and "complete") are recognized on the basis of variation in the lateral row of plates. Among the Norwegian populations, all three morphs were found, but the low morph was by far the most common and occurred mostly in monomorphic populations. The presence of the complete and partial morphs was mostly restricted to young lakes near the sea. It is likely that the plate polymorphism in this region is a transitionary evolutionary stage from a founding population dominated by complete to a monomorphic low population. The hypothesis of a polytypic origin of the low morph is discussed, and an alternative hypothesis is proposed. Within each plate morph, the number of plates also varied, and populations with exceptionally low plate numbers were mostly confined to three different areas. Within these areas, populations with plateless specimens also occurred. These plateless specimens tended to inhabit old lakes. The low plate number and plateless populations were found in parts of Norway that were deglaciated early. The advanced plate reduction can therefore be a result of a longer period of isolation and freshwater evolution. Other populations may be on their way towards extreme plate reduction, but have not yet reached the level of platelessness.

Ardeirhynchus n. g. (Palaeacanthocephala: Polymorphida: Polymorphidae), with a redescription of A. spiralis (Rudolphi, 1809) n. comb.

Ardeirhynchus spiralis (Rudolphi, 1809) n. g., n. comb. (syns Echinorhynchus spiralis, Prosthorhynchus spiralis and Plagiorhynchus spiralis), a parasite of herons (Ciconiiformes: Ardeidae), is redescribed on the basis of the holotype from Ixobrychus minutus and specimens from Ardeola ralloides (new host record) in Bulgaria. A. spiralis is a member of the family Polymorphidae and not of the Plagiorhynchidae in which it was previously classified. Ardeirhynchus n. g. is distinguished from the most morphologically similar genus, Arhythmorhynchus Luhe, 1911, by the position of the male genital system, which occupies the posterior 1/8-1/6 part of the trunk, the distribution of hypodermal nuclei in groups in the anterior part and in lateral rows along the length of the posterior part of the trunk, a considerably shorter neck, minute trunk spines and a terminal genital pore.

Life-cycle, delimitation and redescription of Catatropis verrucosa (Fr�lich, 1789) Odhner, 1905 (Trematoda: Notocotylidae)

The life-cycle of Catatropis verrucosa (Frolich, 1789) Odhner, 1905 has been completed experimentally starting from infected snails collected along the River Danube in Europe. Each stage of the life-cycle is redescribed. Taxonomic problems are discussed and the main features of the species are listed. Synonyms for C. verrucosa are Fasciola verrucosa Frolich, 1789, F. anseris Gmelin, 1790, Monostoma verrucosa (Frolich, 1789) Zeder, 1800, and Catatropis charadrii Skrjabin, 1915. Other names, such as Notocotylus triserialis Diesing, 1839, Notocotyle triseriale (Diesing, 1839) Diesing, 1850, Monostoma verrugueux Dujardin, 1845, “Monostoma sp. du canard” of Blanchard (1847), Notocotyle verrucosum (Frolich, 1789) Monticelli, 1892, N. verruqueux Railliet, 1895, and Distoma verrucosum (Frolich, 1789) Wolffhugel, 1900, were found to represent adults and/or larvae of C. verrucosa. Conversely, but less often, adults and larvae of other species were found described and illustrated as C. verrucosa. One of these, C. verrucosa of Joyeux (1922), was renamed Pseudocatatropis joyeuxi Kanev & Vassilev, 1986. Occasionally, authors actually working with C. verrucosa ascribed their results to different species. Based on experimental life-cycle studies, the following facts were demonstrated. (1) The first intermediate hosts are the prosobranch freshwater snails Bithynia tentaculata (Linnaeus, 1758) and B. leachi (Leach, 1818). (2) The same snails are also first intermediate hosts for Notocotylus imbricatus (Looss, 1893) Szidat, 1935, N. parviovatus Yamaguti, 1934, and N. ponticus Tschiaberaschvili, 1966. In all these species, the species characteristics are expressed by the adult morphology only, and the larvae cannot be identified by morphological criteria. It is proposed that tri-oculate monostome cercariae found in naturally infected B. tentaculata and B. leachi be referred to as “Cercaria imbricata group”. These cercariae include Cercaria imbricata Looss, 1893, C. helvetica I Dubois, 1928, C. triophthalmia Faust, 1930, C. fennica I Wikgren, 1956; C. ephemera of Lutta (1934); C. monostomi of Mathias (1925), Lutta (1934) and Zdun (1961), Cercaria Notocotylus attenuatus of Francalanci & Manfredini (1969), and Monostome cercaria I Emmel, 1943. (3) There is no second intermediate snail host in the life-cycle of C. verrucosa. (4) The final hosts are birds. (5) The adult worms possess, on the ventral body surface, a median ridge and two lateral rows of 12 (range 11–14) papillae per row.