Helobdella nilae sp. nov. (Hirudinoidea: Glossiphoniidae), from the Nile Delta,Egypt

A new freshwater leech species, Helobdella nilae, is described with diagnostically a dorsal nuchal gland (scute) on somite VII, five pairs of simple crop caeca, the last pair extending posteriorly as postcaeca, five pairs of compact spherical testisacs, an unpigmented dorsal surface lacking both papillae and sensilla. The mouth is subapical and surrounded by numerous single or paired pits (pores).     

Reproductive Behaviour and Parental Care of Helobdella striata (Hirudinea,Glossiphoniidae): a Leech that Feeds its Young

The leech Helobdella striata Kutschera (1985) is a protandrous hermaphrodite. It copulates by hypodermic injection: a spermatophore is attached to the skin of the partner and sperm injected through it. During their male phase, the leeches copulate repeatedly and with different partners. In the female phase, 3 to 7 cocoons, each containing 2 to 20 eggs, are produced from the female gonopore and attached to the ventral side of the parent. The larvae which hatch from these eggs cling to the ventral side of the parent. After they have used up their yolk supply and have developed into juvenile leeches they remain attached to the parent for a further three weeks. Helobdella striata capture Tubifex worms and give them to the young they carry. This access to food allows the juveniles to grow from a size of 1 mm to 6 mm length while being carried and protected by the parent. H. striata reared in isolation produce young; at present it is not known whether they reproduce by parthenogenesis or by self-fertilization. The probable phylogenetic development of parental care patterns in the Hirudinea is reviewed.     

A proposal to regard the former family Naididae as a subfamily within Tubificidae (Annelida, Clitellata)

A new species of Placobdelloides is described from crocodiles and river turtles in the Singapore Zoological Gardens. Placobdelloides stellapapillosa is three annulate, has one pair of eyes on somite I or II, six pairs of testisacs, two annuli between the gonopores, one post anal annulus, seven pairs of lobed crop caeca and 12–14 unique star-shaped papillae on the dorsal surface of each annulus. Star-shaped papillae on annulus a2 are typically larger and more pronounced than on annuli a1 and a3. Additional minute cone-shaped papillae may occur between the larger star-shaped papillae or may replace these papillae on annuli a1 and a3. Eggs and young (100–200) are attached by their posterior suckers directly to the ventral surface of the parent.     

Sexual behavior,insemination and development of the freshwater leech Helobdella stagnalis (Annelida,Hirudinea, Glossiphoniidae)

The reproductive biology of the Glossiphoniidae leech Helobdella stagnalis, under laboratory conditions, the structure of its eggs and its developmental stages were studied. Sperm transfer and insemination are made by hypodermic injection: one or numerous spermatophores were attached to the skin of the partner during copulation and sperm is injected through it. The leeches can copulate repeatedly with several partners. Each leech produces 4–8 cocoons containing 20–60 eggs whose are attached to the ventral side of the parent and carried around. At 22 °C, the developmental duration is 24 days from the oviposition until the juveniles leave the parent leech. Three (3) major stages have been distinguished: Eggs cleavage, germinal band generation, and juveniles hatching. The sexual behavior of Hellobdella stagnalis was described with a special attention given to parental care.     

Costs of parental care on hunting behaviour of Helobdella papillornata (Euhirudinea: Glossiphoniidae)

Helobdella papillornata, an Australian freshwater leech, feeds primarily on snails and has a high level of parental care involving brooding eggs and young, with direct feeding of young. Parental costs and offspring benefits from these behaviours are poorly understood. A potential cost of parental care may be a change in the time taken to hunt prey. To test this hypothesis, the hunting behaviour of adults without progeny, parents with eggs, and parents with young were compared. We found that parents brooding eggs had a significantly (P = 0.029) longer lag time to begin hunting than parents brooding young, and spent significantly (P = 0.018) less time actively hunting than non-brooding adults. These costs, which may represent lost potential for the parent’s future reproductive success, should be outweighed by the fitness benefits of improved growth and survival of offspring, if parental care is favoured by selection. The hunting costs of care in Helobdella and other benthic, dorsoventrally flattened leeches in the family Glossiphoniidae may be smaller than the costs of brood tending that would be imposed on other freshwater leeches, and this difference may help explain the restriction of care to a single clade of the Euhirudinea.     

Teloplasm formation in a leech, Helobdella triserialis, is a microtubule-dependent process

Fertilized eggs of the leech Helobdella triserialis undergo a cytoplasmic reorganization which generates domains of nonyolky cytoplasm, called teloplasm, at the animal and vegetal poles. The segregation of teloplasm to one cell of the eight-cell embryo is responsible for a unique developmental fate of that cell, i.e., to give rise to segmental ectoderm and mesoderm. We have studied the cytoplasmic movements that generate teloplasm using time-lapse video microscopy; the formation and migration of rings of nonyolky cytoplasm were visualized using transmitted light, while the movements of mitochondria into these rings were monitored with epifluorescence after labeling embryos with rhodamine 123, a fluorescent mitochondrial dye. To examine the likelihood that cytoskeletal elements play a role in the mechanism of teloplasm formation in Helobdella, we examined the distribution of microtubules and microfilaments during the first cell cycle by indirect immunofluorescence and rhodamine-phalloidin labeling, respectively. The cortex of the early embryo contained a network of microtubules many of which were oriented parallel to the cell surface. As teloplasm formation ensued, microtubule networks became concentrated in the animal and the vegetal cortex relative to the equatorial cortex. More extensive microtubule arrays were found within the rings of teloplasm. Actin filaments appeared in the form of narrow rings in the cortex, but these varied apparently randomly from embryo to embryo in terms of number, size, and position. The role of microtubules and microfilaments in teloplasm formation was tested using depolymerizing agents. Teloplasm formation was blocked by microtubule inhibitors, but not by microfilament inhibitors. These results differ significantly from those obtained in embryos of the oligochaete Tubifex hattai, suggesting that the presumably homologous cytoplasmic reorganizations seen in these two annelids have different cytoskeletal dependencies.     

Holotype redescription of Mimobdella japonica (Hirudinida, Arhynchobdellida, Erpobdelliformes) and taxonomic status of the genus Mimobdella

Mimobdella japonica Blanchard, 1897, the type species of the genus Mimobdella Blanchard, 1897, is redescribed based on the holotype. This species is characterized by the following characteristics: mid-body somites novem-annulate, two post-anal annuli, male gonopore in XI/XII, female gonopore in XII/XIII, 9 annuli (one full somite) between gonopores, strepsilaematous pharynx and three myognaths with stylets, possessing post-crop caeca in pairs, ovisacs reaching to XXI a2. The genus Mimobdella is placed under the family Salifidae, not Gastrostomobdellidae or Erpobdellidae, according to its possessing three myognaths bearing pharyngeal stylets.     

Cultivating Lithoglyphopsis aperta Temcharoen, a new snail host for Schistosoma japonicum, Mekong strain.

Lithoglyphopsis aperta Temcharoen, a new intermediate host for Schistosoma japonicum, Mekong strain, was cultivated successfully through the F2 generation with the use of a petri dish aquarium provided with mud and alga. The incubation period of eggs was about 4 weeks; the young grew to maturity in 16 to 20 weeks; egg-laying followed about 6 to 8 weeks later, the cycle taking roughly 6 months. The husked eggs were deposited exclusively at the edge and wall of the aquarium. Eggs were hemispherical and with the husks were between 0.37 and 0.43 mm in diameter. The newly hatched young were only 0.24 mm in shell length and the full-grown snails were 3.11 to 3.36 mm long. Logarithmic growth began between the 12th and 14th weeks.     

Spawning habitat and early development of Luciogobius ryukyuensis (Gobiidae)

Egg masses of Luciogobius ryukyuensis were found in spawning grounds around the lowest reach of the adult??s habitat in the tidally influenced area of streams on Okinawa Island. The eggs were attached to the underside of stones and were cared for by a solitary male fish. The number of eggs within an egg mass was 191?C1368. The eggs were elliptical, measuring 2.0?C2.6?mm in length, and 0.6?C0.8?mm in width. Early development of L. ryukyuensis was described from laboratory-reared specimens. Newly hatched larvae, measuring 2.8?C3.3?mm in body length, had an open mouth, pigmented eyes, pectoral fin buds, an orange-colored yolk sac, and characteristic melanophores along the dorsal and ventral midlines of the body. The yolk was completely absorbed at days 2?C3. Notochord flexion began at day 10 and was completed at day 15. The fish started settling on the bottom of the tank at day 34 (14.1?mm in body length) when the body surface started to be covered by intense pigmentation. The eggs and newly hatched larvae of L. ryukyuensis were of standard size of the genus and their morphologies closely resemble those of L. guttatus.     

DNA barcoding reveals Mexican diversity within the freshwater leech genus Helobdella (Annelida: Glossiphoniidae)

We investigated the genetic distances and taxonomic status among species of Helobdella, a genus of non-blood-feeding leeches, based on mitochondrial cytochrome c oxidase subunit I sequences. Sampling included 20 specimens representing nine nominal species collected in 11 states in Mexico as well as previously published sequences of different species of Helobdella from several places. A neighbor-joining tree, as well as identification of diagnostic nucleotides, was used to suggest the presence of seven species of Helobdella in Mexico including potentially two undescribed forms.     

A new molecular logic for BMP-mediated dorsoventral patterning in the leech Helobdella

Bone morphogenetic protein (BMP) signaling is broadly implicated in dorsoventral (DV) patterning of bilaterally symmetric animals [1-3], and its role in axial patterning apparently predates the birth of Bilateria [4-7]. In fly and vertebrate embryos, BMPs and their antagonists (primarily Sog/chordin) diffuse and interact to generate signaling gradients that pattern fields of cells [8-10]. Work in other species reveals diversity in essential facets of this ancient patterning process, however. Here, we report that BMP signaling patterns the DV axis of segmental ectoderm in the leech Helobdella, a clitellate annelid (superphylum Lophotrochozoa) featuring stereotyped developmental cell lineages, but the detailed mechanisms of DV patterning in Helobdella differ markedly from fly and vertebrates. In Helobdella, BMP2/4s are expressed broadly, rather than in dorsal territory, whereas a dorsally expressed BMP5-8 specifies dorsal fate by short-range signaling. A BMP antagonist, gremlin, is upregulated by BMP5-8 in dorsolateral, rather than ventral territory, and yet the BMP-antagonizing activity of gremlin is required for normal ventral cell fates. Gremlin promotes ventral fates without disrupting dorsal fates by selectively inhibiting BMP2/4s, not BMP5-8. Thus, DV patterning in the development of the leech revealed unexpected evolutionary plasticity of the conserved BMP patterning system, presumably reflecting its adaptation to different modes of embryogenesis.     

Phylogeny and revision of the leech genus Helobdella (Glossiphoniidae) based on mitochondrial gene sequences and morphological data and a special consideration of the triserialis complex

The relationships, as well as identification of species, within Helobdella (Glossiphoniidae) were explored through phylogenetic analysis and through an overview of the historical systematics of the genus. The phylogeny was determined using morphological data and the mitochondrial gene sequences of cytochrome c oxidase subunit I and nicotinamide adenine dinucleotide dehydrogenase subunit I. A broad representation of 15 ingroup species was sampled, including 10 individuals from South America. Outgroup taxa included five species of Haementeria . Cladistic analysis of all available data resulted in one most parsimonious tree. Results shed light on genetic divergence of members classified as the same species, including those that are not monophyletic. Historically, external morphological characters have played a significant role in contributing to the confusion in the classification of H. triserialis, H. papillata, H. lineata and H. fusca in North America. Re-evaluation of Verril's Clepsine papillifera var. b and var. d in a phylogenetic context provides a solution. Additionally, the genera Adaetobdella, Acritobdella, Dacnobdella and Gloiobdella created by Ringuelet are returned to Helobdella based on overlapping morphological characters.     

A new species of Alboglossiphonia (Hirudinea: Glossiphoniidae) from Egypt

A new Alboglossiphonia species from Egypt is described and figured. This leech is placed in the genus Alboglossiphonia on the basis of having three pairs of eyes, diffuse salivary glands, seven pairs of crop caeca, and the attachment of its eggs to the venter. It differs from other Alboglossiphonia species with seven pairs of crop caeca in its combination of very prominent dorsal papillae, two annuli between the gonopores, lobed first six pairs of crop caeca, and paired ducts of male system at peak of activity with conspicuously differentiated sperm duct, seminal vesicle and ejaculatory duct regions.     

Micromere lineages in the glossiphoniid leech Helobdella

In leech embryos, segmental mesoderm and ectoderm arise from teloblasts by lineages that are already relatively well characterized. Here, we present data concerning the early divisions and the definitive fate maps of the micromeres, a group of 25 small cells that arise during the modified spiral cleavage in leech (Helobdella robusta) and contribute to most of the nonsegmental tissues of the adult. Three noteworthy results of this work are as follows. (1) The c"' and dm' clones (3d and 3c in traditional nomenclature) give rise to a hitherto undescribed network of fibers that run from one end of the embryo to the other. (2) The clones of micromeres b" and b"' (2b and 3b in traditional nomenclature) die in normal development; the b" clone can be rescued to assume the normal c" fate if micromere c" or its clone are ablated in early development. (3) Two qualitative differences in micromere fates are seen between H. robusta (Sacramento) and another Helobdella sp. (Galt). First, in Helobdella sp. (Galt), the clone of micromere b" does not normally die, and contributes a subset of the cells arising exclusively from c" in H. robusta (Sacramento). Second, in Helobdella sp. (Galt), micromere c"' makes no definitive contribution, whereas micromere dm' gives rise to cells equivalent to those arising from c"' and dm' in H. robusta (Sacramento).     

Cell interactions in the developing epidermis of the leech Helobdella triserialis

In embryonic development of the leech Helobdella triserialis, each of the four paired ectodermal teloblasts contributes some progeny to a characteristic dorsal or ventral territory of the epidermis. To ascertain the relative roles of cell lineage and cell interactions in generating the highly regular epidermal distribution pattern of the various ectodermal cell lines, a series of experiments was carried out in which the ablation of particular teloblasts was combined with the intracellular injection of cell lineage tracers. The results showed that, after the ablation of an OP proteloblast, or of an O, P, or Q teloblast, the epidermal progeny of the remaining ipsilateral and contralateral teloblasts spread into the territory normally occupied by the epidermal progeny of the ablated teloblast. In this spreading process, cells may cross the ventral midline but not the dorsal midline. The spread of epidermal progeny of one teloblast in response to ablation of another teloblast is contrasted with the failure of the neuronal progeny of one teloblast to replace any missing neural tissue. It appears, therefore, that all epidermal cell lines are of equal developmental potential, regardless of their teloblast of origin, with the eventual location of any epidermal cell in the body wall being governed by interactions between cells within the developing epidermis.     

The reproductive biology of Theromyzon tessulatum (Glossiphoniidae: Hirudinoidea), with comments on Theromyzon rude

The reproductive biology and behaviour of Theromyzon tessalatum is described from the commencement of copulation to the release of the young and the death of the parent. Copulation occurs several times over a10–20 day period with either the same or different partners. Eggs were laid6–14 days after copulation in usually four cocoons each containing approximately 100 eggs. The cocoons were brooded by the parents and the young, on development of the embryonic attachment organ and later by the posterior sucker, attached to the ventral surface of the parent's abdomen. The young detached from the parent either on contact with a suitable host for a blood meal or after approximately five months just prior to the parent's death.     

The reproductive biology of the leech Helobdella stagnalis (L.) in Utah Lake, Utah

The reproductive biology of the glossiphoniid leech Helobdella stagnalis in Utah Lake, Utah was studied for an 18-month period from June 1970 to December 1971. In this lake it was found that the overwintering adult leeches produce two broods of young in May and June. Evidence is presented to support the idea that the same individual can produce two broods. Two complete cycles of gametogenesis also take place. Continuous water temperatures were recorded at the study site to correlate with reproductive activity. Gametogenesis appears to be temperature dependent with the first generation of sperm taking 4 months to be produced in the fall and winter months while the second generation of sperm is produced in 6 weeks during the spring. Egg production follows a similar pattem.     

太湖乔氏短吻银鱼的生物学

太湖产乔氏短吻银鱼于3月中旬至5月末产卵。卵具粘性。集中在有沉水植物着生的湖湾内产卵。生殖周期短,一年可达性成熟。繁殖力强。在水温14.5—25.0℃时,仔鱼在受精后118小时23分孵出。终生以浮游动物为食。生长较缓慢,接近一年才达上市规格。其寿命只一年,产卵后不久死亡。保护其产卵基质——沉水植物,以及适当地扩大银鱼网的网目,是关键的增殖措施。       

Are the lake-dwelling leeches,Glossiphonia complanata (L.) and Helobdella stagnalis (L.), opportunistic predators on molluscs and do they partition this food resource?

SUMMARY. 1. Predation on the mollusc genera Potamopyrgus, Bithynia, Valvata, Lymnaea, Physa, Planorbis and Pisidium by the leeches Glossiphonia complanata (L.) and Helobdella stagnalis (L.) was examined in five eutrophic lakes at monthly intervals over one year using a serological technique.
2. Feeding intensity varied seasonally, being lowest in winter and highest in summer. Small, medium and large leeches preyed to the same extent on the several mollusc genera; this was true for both leech species. Qualitatively, the diet of both glossiphoniids was similar throughout the year. Snail genera were consumed in proportion to their relative abundance in the field. Quantitatively, Glossiphonia preyed more heavily on snails than did Helobdella.
3. It is concluded that both leech species are opportunistic predators.     

Embryonic development,larvae and juvenile of elkhorn sculpin,Alcichthys alcicornis

The eggs ofAlcichthys alcicornis were spawned in tank at the laboratory and reared for the studies of embryonic, larval and juvenile development. This species takes place entosomatic fertilization, and females spawn fertilized eggs after copulation. The eggs are demersal and adhesive, released as a clump forming a thin layer on the bottom of tank. There was no significant difference in embryonic development between this species and other oviparous teleostean species. Hatching occurred between 17 and 18 days after spawning at a mean water temperature of 8.5?C. The newly hatched larvae averaged 4.44 mm in body length (BL). The larvae attained to post-larval stage at 5.80 mm BL, and juvenile stage at 10.2 mm BL. A specific feature of the post-larvae was the appearance of three lines of the melanophores on the caudal part of fin fold. Carotenoid first appeared on the nape at 8.70 mm BL, heavily emerged beyond 12.9 mm BL, and turned up on the back also beyond 15.2 mm BL. Scales on the lateral line were completed by 18.5 mm BL. Three pairs of flaps were observed on the dorsal surface of the head at 37.0 mm BL. External features of adult specimens are almost completed by 52.0 mm BL, yet the tip of the first preopercular was not branched but remained simple.