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.     

Experimental observations on the specificity of Apatemon (Australapatemon) minor (Yamaguti 1933) (Digenea: Strigeidae) toward leech (Hirudinea) second intermediate hosts

The infectivity of Apatemon (Australapatemon) minor cercariae to 7 species of freshwater leech was examined under laboratory conditions. The leech species exposed to infection were; Erpobdella octoculata, Helobdella stagnalis, Glossiphonia heteroclita, Glossiphonia complanata, Hemiclepsis marginata, Piscicola geometra, and Theromyzon tessulatum. Five species were capable of acting as second intermediate hosts. Despite this broad specificity only Erpobdella octoculata and Helobdella stagnalis could be considered to show a high degree of compatibility with the parasite. In these 2 leech species more than 38% of the cercariae successfully penetrated and established metacercarial cyst infections. The leeches Piscicola geometra and Theromyzon tessulatum did not become infected. Close parallels were found between the species order of host utilization determined experimentally and that revealed by a range of field surveys in Britain, Eastern Europe and Russia. This suggests that the order of second intermediate host utilization in the natural environment has, at least in part, a physiological basis. The degree to which different leeches are utilized as hosts may relate to the opportunity which they afford for transmission of A. minor to wildfowl definitive hosts.     

The incidence of predation on lake-dwelling leeches

SUMMARY. 1. Erpobdella octoculata (L.), Glossiphonia complanata (L.) and Helobdella stagnate (L.) were eaten readily by larval and adult dytiscid beetles, larval caddisflies and Sialis , nymphal odonatans and various fish in laboratory experiments.
2. A serological technique showed that very few lake-collected specimens of these predatory taxa, plus triclads, leeches and stone fly nymphs, had been feeding on leeches.
3. A literature survey of lake studies on fish diet indicated that usually less than 6% of individuals with gut contents had eaten leeches. Few detailed records of waterfowl feeding on leeches have been documented.
4. It is concluded that predation pressure on lake-dwelling leeches is light, and is more severe from fish than invertebrates, less on populations inhabiting stony shores than in vegetation, and greater on the erpobdellid than the two glossiphoniid species.     

The effects of procaine, strychnine and penicillin on nociceptive neurons in leech segmental ganglia

Procaine, strychnine and penicillin selectively depolarized the membrane potential and prolonged the action potential recorded in the lateral but not the medial nociceptive (N) cell in the hirudinid leech Macrobdella decora. In contrast, procaine did not differentiate between medial and lateral N cells in two other hirudinid leeches Hirudo medicinalis and Haemopis marmorata. In these species, the drug equally decreased the amplitude of action potentials in both types of N cells without effecting their resting membrane properties. In the nociceptive neurons of the glossiphoniid leech Haementeria ghilianii which possesses only one type of N cell, procaine produced a depolarization and prolonged the action potential. This finding indicates that the single pair of N cells in Haementeria is of the lateral type. The results suggest that the lateral type N cell in Macrobdella and Haementeria share a unique Na+-dependent conductance which is selectively opened by the local anesthetics procaine and strychnine as well as by penicillin. This conductance is either not present or insensitive to the drugs in the homologous N cells in the two other leech species examined.     

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.     

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.     

Predation on leeches in a weedy pond

SUMMARY. 1. A range of sizes of Erpobdelta octoculata fL.), Glossiphonia complanata (L.) and Helobdella stagnalis (L.) were introduced to a small weeded pond harbouring invertebrate and amphibian predators. Control leeches were kept in protective cages. Subsequently, gut contents of potential predators were tested against three anti-leech sera, using the precipitin test. Five of fifteen species tested had fed on leeches; Agabus, Pyrrhosoma, Aeshna, Sympetrum and larval Trilurus.
2. The size distributions of introduced and surviving leeches were compared. Predation pressure had been greatest on smaller leeches and this may have accounted for the observed differential mortality between leech species.
3. It is concluded that predation may cause significant mortality in leech populations in weeded ponds, with severity determined by the types and abundance of predators present.     

DNA-barcoding evidence for widespread introductions of a leech from the South American<Emphasis Type="Italic">Helobdella triserialis</Emphasis> complex

Morphological examination and a molecular phylogenetic analysis of leeches from Australia, New Zealand, South Africa and Hawaii show that these specimens are members of a species in the South American Helobdella triserialis species complex. Though it has been seen before, this leech was not recognized as an invasive species. Rather, it was first described as Helobdella striata from Germany later renamed Helobdella europaea and then independently described as Helobdella papillornata from Australia. Because the appropriate name for this leech from its South American endemic locale, Helobdella (triserialis) lineata, is preoccupied by a North American species, we formally recognize H. europaea as the valid taxon name. Although this invader is not a bloodfeeder it may be expected to have an impact on native annelid and mollusk faunas.     

Freshwater leeches from Yemen

The occurrence of freshwater leeches in ten different wadis in Yemen was determined. Four species were recorded for the first time: Batracobdelloides tricarinatus, Helobdella conifera, Limnatis nilotica and Placobdelloides multistriatus. These species, typically found in Africa, are recorded in Yemen on the border of two biogeographical regions.     

The occurrence of metacercariae of the trematode, Cyathocotyle opaca (Wisniewski), in three species of lake-dwelling leeches

SUMMARY. 1. The leeches, Erpobdella octoculata, Glossiphonia complanata and Helobdella stagnalis , were collected at monthly intervals over a 2-year period from a eutrophic English lake, and examined for the presence of metacercariae of the trematode. Cyathocotyle opaca.
2. Only one specimen of each of H. stagnalis and G. complanata was recorded with the parasite. Seasonal changes in prevalence levels in E. octoculata were similar for each of the three cohorts identified during the study period. Values, low in young leeches recruited in the autumn, rose slowly until the following spring, and then increased more rapidly till the autumn, when the cohort died out. Mean intensity and relative density showed similar patterns of seasonal change to that of prevalence.
There was no evidence of parasite induced mortality in E. octoculata. Attainment of sexual maturity did not differ between infected and uninfected leeches.     

Protein mapping of the salivary complex from a hematophagous leech

The salivary complex of leeches contains many components able to modulate physiological mechanisms, such as coagulation and fibrinolysis, and it is composed by the salivary glands and proboscis, encompassing two different proteomes. The bidimensional electrophoretic pattern of the salivary complex from the Haementeria depressa leech revealed a total of 352 spots, 103 in common with the muscular tissue and 249 exclusive from the salivary complex as detected by silver staining; these spots showed isoelectric points from 3.5 to 9.5 and covered an apparent molecular weight range from 10 to 105 kDa. The following isoforms of proteins were identified by mass spectrometry analysis: antiplatelet protein, myohemerythrin and carbonic anhydrase. Since the leeches were not fed for about 2-3 months to stimulate the secretion of proteins that facilitates the blood metabolism, these most abundant proteins in the salivary complex excised from leeches, are expected to play a role during feeding and might have some anti-hemostatic properties. Furthermore, by zymography, a gelatinolytic and a fibrinolytic protein were identified.     

Serotonin is released from isolated leech ganglia by potassium-induced depolarization.

1. The quantities of serotonin that are released from isolated leech ganglia in vitro were measured with the sensitive neurochemical techniques of HPLC-EC. 2. Segmental ganglia were exposed to elevated concentrations of potassium that depolarize leech serotonin-containing neurons by approximately 35 mV per decade. 3. Each segmental ganglion released on average 0.20 pmol of serotonin during 10 min of incubation in a solution containing 64 mM K+. 4. The rate of serotonin release increased nearly four-fold to 0.74 pmol/10 min when ganglia were incubated in 120 mM K+. 5. The rates of ganglionic serotonin release in 120 mM K+ were quantitatively similar in these three, experimentally important species of leeches: Hirudo medicinalis, Macrobdella decora and Haementeria ghilianii. 6. Ionic substitution experiments with the divalent cations Mg2+ and Co2+ indicated that the release of serotonin from leech ganglia is mediated by a Ca2+ dependent process. 7. The serotonin-uptake blockers, imipramine and chlorimipramine, did not increase the amount of serotonin released in elevated potassium. 8. Vitally staining the identified serotonin-containing neurons with Neutral Red dye did not reduce the quantity of serotonin that was released from the ganglia in elevated potassium. 9. This study demonstrates the capacity of leech ganglia to release the neurochemical serotonin, and the rates of transmitter release increase with the degree of depolarization of serotonin-containing neurons.     

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.     

Haementeria costata (Hirudinea: Glossiphoniidae), a leech new to Britain

SUMMARY. The European leech Haementeria costata is recorded in Britain for the first time and is described in detail. A key is provided to distinguish H. costata from other species of leeches in Britain, and the literature on the ecology of H. costata is summarized.     

Hyaluronidase activity in leeches (Hirudinea)

The leech hyaluronoglucuronidase (hyaluronidase I) was identified in Erpobdellidae (Nephelopsis obscura and Erpobdella punctata) and Glossiphoniidae (Desserobdella picta) and historically described from Hirudinidae (Hirudo medicinalis). A second leech hyaluronidase (hyaluronidase II) which hydrolyzed only a few bonds to for hyaluronan oligosaccharides larger than 6500 Da, was found in Glossiphoniidae (Helobdella stagnalis, Glossiphonia complanata, Placobdella ornata, and Theromyzon sp.) and in Haemopidae (Haemopis marmorata). The distribution of the two hyaluronidases in leech occurred in both orders (Arhynchobdellida and Rhynchobdellida) and in macrophagous and haematophagous feeding types whereas the liquidosomatophagous leeches only had hyaluronidase II.     

Food utilization and niche overlap in three species of lake-dwelling leeches (Hirudinea)

The diets of Erpobdella octoculata, Glosiphonia complanata and Helobdella stagnalis on the stony littoral zone of eutrophic Crose Mere were examined over two years using the precipitin test. The abundances of food organisms were measured. For all leech species, juvenile mortality was greatest in locations where a low ratio of prey abundance to recruited leech abundance occurred, and the intensity of feeding by Erpobdella and Helobdella fell slightly in late summer when large numbers of juveniles of these species were present; these suggest the involvement of food in juvenile mortality, Seasonal changes in feeding intensity were similar for all leech species, with the exceptions outlined above and for Glossiphonia in April when feeding by brooding adults ceased, at which time the severity of any interspecific competition would have been reduced. Within a leech species, there was little change in the food spectrum as the leeches grew. Niche breadth was lowest for Erpobdella and highest for Helobdella. Niche overlap was greatest between Glossiphonia and Helobdella, and there was a trend for overlap values to be lower between Glossiphonia and Erpobdellu than between Helohdellu and Erpohdellu. Erpobdella fed mainly on chironomids and oligochaetes, Glossiphonia on molluscs, oligochaetes and chironomids, and Helobdella on oligochaetes, chironomids, Asellus, molluses and amphipods, all in decreasing order of importance. It is suggested that coexistence in the leech species may be due in part to Erpobdella and Glossiphonia having 'food refuges' in chironomids and molluscs, respectively, with Helobdellu being more of a general predator.     

The influence of temperature on the life cycle and occurrence of three species of lake-dwelling leeches (Annelida: Hirudinea)

The influence of constant temperatures on the growth, maturation and reproduction of field-collected and F, generation Helobdella stagnalis, Glossiphonia complanata and Erpobdella octoculata was investigated. Leech material from a lowland, productive lake and from an upland, unproductive lake was cultured at each of the temperatures: l·5,5·5,8, 10·5, 13,16, 19 and 23°C. Field-collected and F₁ generation H. stagnalis and E. octoculata matured and produced eggs and young over the range 10·5–23°C, whereas the range for egg production was 8–23°C for field-collected G. complanata, F, generation leeches failing to mature at any temperature due to an additional limiting factor being involved.
Optimal temperatures for cocoon/egg production were observed for E. octoculata, but egg production was similar at all temperatures for G. complanata and H. stagnalis. In contrast, the viability of eggs was greater at certain temperatures for the last two species but was similar at all temperatures for E. octoculata. Differences in egg production between field-collected and F, generation leeches are discussed. Rising temperatures accelerated rates of egg hatching, and of growth and maturation of leeches. The observed differences in survival of leeches at the various temperatures are discussed. Ecotypic adaptation to temperature within the small geographical area of Britain may not occur. It is concluded that though temperature may be a contributory factor determining distribution and abundance in British lakes, other causative factors, such as the occurrence and abundance of food organisms, are more likely to be implicated.     

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.     

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).     

A new species of marine leech (Hirudinida: Piscicolidae) from giant kelpfish, Heterostichus rostratus Girard, in southern California

Collections of giant kelpfish at inner Cabrillo Beach, San Pedro, California revealed the presence of an undescribed species of Heptacyclus, described here as Heptacyclus cabrilloi n. sp. The leech is small, only up to 14 mm total length including suckers; it has 2 pair of slightly crescentiform eyes on the oral sucker, 1 pair of punctiform ocelli on the second annulus of the trachelosome, 13 pairs of punctiform ocelli dorsally and ventrally on the urosome, and 14 marginal punctiform ocelli on the caudal sucker. Pigmentation is yellowish-tan with an unpigmented mid-dorsal stripe on both trachelosome and urosome, and with unpigmented halos around eyespots and urosome ocelli. Male reproductive system with 5 pairs of large, spherical testisacs. Mycetomes present, accessory gland cells on atrial cornu absent. Prevalence was 24.1% in June, 2011 with a range of 1-2 leeches per fish and 25.8% in October, 2011 with a range of 1-6 leeches per fish.