Unoculubranchiobdella sp. (Hirudinea: Ozobranchidae) as a vector for Haemogregarina spp. in freshwater turtles from Brazil.

Species of Haemogregarina are blood parasites known to parasitise vertebrate hosts, including fishes (Haemogregarina sensu lato) and freshwater turtles (Haemogregarina sensu stricto). Their vectors, include gnathiid isopods and leeches, respectively. In turtles, Haemogregarina balli has the best-characterized life cycle in the genus. However, no studies in Brazil have suggested a possible vector for any species of Haemogregarina from freshwater turtles. Therefore, in the present study, we provide insights into a leech vector based on specimens found feeding on two species of freshwater turtles, Podocnemis unifilis and Podocnemis expansa, using morphological and molecular data. In 2017 and 2019, freshwater turtles were collected in Goiás State, Brazil. Hosts were inspected for ectoparasites and leeches were collected from two specimens of P. expansa and nine specimens of P. unifilis. Leeches were subsequently identified as members of the genus Unoculubranchiobdella. Leech histological slides revealed haemogregarine-like structures, similar to post-sporogonic merogony, found near the gills and within the posterior sucker. Molecular analysis of the haemeogregarines resulted in the identification of three species of Haemogregarina: Haemogregarina embaubali, Haemogregarina goianensis, and Haemogregarina brasiliana. Therefore, our findings, based on morphology and DNA data suggest leeches of the genus Unoculubranchiondella as vectors for at least three species of Haemogregarina from Brazilian turtles.

Not that many leech species after all: Myzobdella lugubris and Myzobdella patzcuarensis (Annelida: Hirudinida) are the same species.

The genus Myzobdella groups five species of leeches parasites of fishes mainly of freshwater but with tolerance to brackish waters. Native distribution of these species includes the New World from North to South America. Myzobdella lugubris Leidy, 1851, the type species of the genus, was briefly described based on specimens from the USA, but subsequently their morphology, known distribution and host range were expanded; however, less is known about the other four species of the genus. As part of a survey focusing on characterizing the diversity of leeches from Mexico, specimens of Myzobdella patzcuarensis (Caballero, 1940), from the type locality of the species were included for the first time in a phylogenetic study. In addition, specimens assigned to Myzobdella from the southeast of Mexico as well as from Nicaragua, were also included. In the resulting phylogenetic tree, our newly generated sequences were found nested in the same clade that M. lugubris; with unresolved relationships and relatively low genetic divergence, suggesting conspecificity. In addition, the internal morphology of the specimens of Myzobdella from Mexico is consistent with the description of M. lugubris. Our morphological examination reveals high degrees of variability in the external pigmentation of the specimens. Based on our results we formally synonymize M. patzcuarensis under M. lugubris.

A high-altitude population of Hyperboreomyzon polaris (Hirudinea: Glossiphoniidae) in Altai Mountains, South Siberia, Russia.

Hyperboreomyzon polaris Bolotov, Eliseeva, Klass & Kondakov, 2022 (Hirudinea: Glossiphoniidae) is an enigmatic freshwater leech that was recently described based on three specimens from two remote regions of the Eurasian Arctic, that is, the Kolguev Island and Putorana Plateau, Russia. Later on, misidentified historical samples of this species were discovered in the Hirudinea collection of Zoological Institute of the Russian Academy of Sciences (St. Petersburg, Russia). These samples were collected by Pavel G. Ignatov, a prominent Russian geographer and traveler, from a remote high-altitude area of the Altai Mountains (South Siberia) in 1901. To collect new samples from this population, we organized a field expedition to the same area (Lake Dzhulukul) in 2023. Molecular genetic data (COI and 18S rRNA) obtained from newly collected specimens revealed that they belong to H. polaris. Hence, this leech could be considered an Arctic-alpine species, the disjunctive range of which covers Arctic areas of Eurasia and Central Asian (South Siberian) mountains. We describe and illustrate living individuals of H. polaris for the first time, update its morphological diagnosis, present a life cycle reconstruction based on the frequency of four size classes in available samples. It is shown that this species prefers small lentic water bodies such as small lakes and lakelets. The crop content of a well-fed specimen from Altai contains DNA of the northern pintail Anas acuta Linnaeus (Aves: Anatidae), indicating that H. polaris feeds on blood of waterfowl. Our results indicate that Hyperboreomyzon may be considered a species adapted to cold high-latitude areas and mountain refugia.

Placobdella nabeulensis sp. nov. (Hirudinea: Glossiphoniidae), a new glossiphoniiform leech from Palearctic North Africa.

BACKGROUND: Herein, we describe a new species of turtle blood-feeding leech, Placobdella nabeulensis sp. nov. from Palearctic North Africa (Tunisia and Algeria). The new species is described based on detailed morphological analyses using light and scanning electron microscopes. RESULTS: Apart from the detailed morphology of the atrium, morphological features alone do not sufficiently separate the species from congeners due to the absence of distinct diagnostic characters. Therefore, we turned to molecular data to better distinguish this new species from other members of the genus and establish a basis for its genetic separation. Four DNA fragments were successfully amplified, including mitochondrial COI and 12S rDNA, as well as nuclear 28S rDNA and histone H3. We then provided the molecular descriptor of the taxon, based on redundant diagnostic nucleotide combinations in DNA sequence alignment within the Folmer region. Results of the phylogenetic analysis and species delimitation methods (ABGD, ASAP, and bPTP) based on the COI locus support the species rank of the Tunisian-Algerian Placobdella. CONCLUSIONS: The new species is most closely related to the European species Placobdella costata (Fr. Müller, 1846) and the present study indicates that Placobdella nabeulensis sp. nov. has likely been confused with the European counterpart in several previous studies. This article is registered at www.zoobank.org under urn:lsid:zoobank.org:pub:4A4B9C1D-2556-430F-8E4B-0CE99F2012F5.

Batracobdelloides bangkhenensis sp. n. (Hirudinea: Rhynchobdellida), a new leech species parasite on freshwater snails from Thailand.

A new snail-eating leech, Batracobdelloides bangkhenensis sp. n., was discovered at Kasetsart University, Bangkhen Campus, Bangkok, Thailand. This species is found free living in the benthic zone of ponds; feeds on freshwater snails, including Bithynia siamensis siamensis, Indoplanorbis exustus, Radix rubiginosa, Physella acuta, and Pomacea canaliculata; and uses a shell as a shelter during the parental care period, with a colony of 7-15 juvenile individuals held on the venter inside the shell of host. Batracobdelloides bangkhenensis displays distinct morphological characters, including a rice-shaped body showing transparency, cephalization, two eye pairs merged on somite III, an anterior sucker twice as large as the cephalic region, a central mouth in the anterior sucker, seven light brown transverse rows in the neck region, absent dorsal papillae, rich green pigments on the dorsum, a male gonopore on XIIa2/XIIa3 (27-28), a female gonopore on XIIIa1/XIIIa2 (29-30), and diffuse aggregations of minute, spherical salivary glands in the neck region. Comparisons of the COI and COI-ND1 genes showed a monophyletic clade for Batracobdelloides, and the phylogenetic tree of the COI gene also indicated that B. bangkhenensis is distinct from other species in the genus, with strong support values.

A new freshwater leech species from Asian Swamp Eel stocks in China.

Discoveries of new Hemiclepsis species (Hirudinea: Glossiphoniidae) in East and Southeast Asia were expected. A peculiar freshwater leech was found on the body surface of Asian Swamp Eel Monopterus albus (Synbranchiformes: Synbranchidae) in Jingzhou, Hubei Province, China. Here, we describe this leech species as Hemiclepsis yangtzenensis sp. nov. It could be distinguished from other congeners based on a combination of morphological features such as very small size, translucent body with dense green reticulate markings throughout dorsum, very large posterior sucker with a characteristic reticulate pattern, and two pairs of well-developed drop-like eyespots. It also represents a phylogenetic lineage that is distant from other members of the genus based on the COI and 18S rRNA sequences. This leech species seems to be a specialized fish parasite that could negatively affect farming and wild stocks of Asian Swamp Eel in China.

Placobdelloides tridens sp. n., a new species of glossiphoniid leech (Hirudinea: Rhynchobdellida) found feeding on captive Orlitia borneensis in Thailand, and an update to the host distribution of P. siamensis.

A new glossiphoniid leech species, Placobdelloides tridens sp. n., is discovered on the Malayan Giant Turtle (Orlitia borneensis) at the Nakhon Ratchasima Zoo in Thailand. The morphological study of this new species revealed that it is distinguished from P. siamensis, a turtle leech species that can be found commonly in Thailand. Placobdelloides tridens presented the following diagnostic morphological characteristics: a pear-shaped and triannulate body, well-developed rod-like papillae on the dorsal surface, smooth posterior and anterior suckers with nominal pits inside, a single pair of dark contiguous eyes, light yellow-brown to greenish dorsal color, absence of median line, male and female gonopore separated by a single annulus and a unique trident shape at the tip of the crop ceca. The phylogenetic relationships of P. tridens sp. n., was clarified, and shown to be a sister clade to the P. siamensis and P. sirikanchanae clade. Furthermore, this is a new host record for P. siamensis, which was found on O. borneensis, Batagur affinis and B. borneoensis in the Khao Kheow Open Zoo, Chonburi, Thailand.

On the origin of leeches by evolution of development.

Leeches are a unique group of annelids arising from an ancestor that would be characterized as a freshwater oligochaete worm. Comparative biology of the oligochaetes and the leeches reveals that body plan changes in the oligochaete-to-leech transition probably occurred by addition or modification of the terminal steps in embryonic development and that they were likely driven by a change in the feeding behavior in the ancestor of leeches. In this review article, developmental changes that are associated with the evolution of several leech-specific traits are discussed. These include (1) the evolution of suckers, (2) the loss of chaetae, (3) the loss of septa, and (4) a fixed number of segments. An altered developmental fate of the teloblast is further proposed to be a key factor contributing to the fixation of the segment number, and the evolutionary change in teloblast development may also account for the loss of the ability to regenerate the lost body segments in the leech.

Insights into bilaterian evolution from three spiralian genomes.

Current genomic perspectives on animal diversity neglect two prominent phyla, the molluscs and annelids, that together account for nearly one-third of known marine species and are important both ecologically and as experimental systems in classical embryology. Here we describe the draft genomes of the owl limpet (Lottia gigantea), a marine polychaete (Capitella teleta) and a freshwater leech (Helobdella robusta), and compare them with other animal genomes to investigate the origin and diversification of bilaterians from a genomic perspective. We find that the genome organization, gene structure and functional content of these species are more similar to those of some invertebrate deuterostome genomes (for example, amphioxus and sea urchin) than those of other protostomes that have been sequenced to date (flies, nematodes and flatworms). The conservation of these genomic features enables us to expand the inventory of genes present in the last common bilaterian ancestor, establish the tripartite diversification of bilaterians using multiple genomic characteristics and identify ancient conserved long- and short-range genetic linkages across metazoans. Superimposed on this broadly conserved pan-bilaterian background we find examples of lineage-specific genome evolution, including varying rates of rearrangement, intron gain and loss, expansions and contractions of gene families, and the evolution of clade-specific genes that produce the unique content of each genome.

New Antarctic deep-sea weird leech (Hirudinida: Piscicolidae): morphological features and phylogenetic relationships.

A new fish leech Ambulobdella shandikovi n. g., n. sp. (Hirudinida: Piscicolidae), a parasite of Whitson's grenadier Macrourus whitsoni (Regan) (Macrouridae: Gadiformes) collected in the Ross Sea at depths from 1,221 to 1,433 m, is described and compared with related taxa based on morphological and molecular characters. Ambulobdella shandikovi n. sp. is characterised by prominent segmental tubercles on the venter and dorsal segmental tubercles, an uncommon appearance of its anterior sucker with ear-like edges and an inner membrane around the mouth-pore, well-developed musculature and a unique combination of features of the reproductive and digestive systems. The presence of uncommon tubercles can be attributed, in part, to temporary associations of A. shandikovi n. sp. with its fish hosts and a need for well-developed sensory and locomotory organs. A certain locomotory function of ventrolateral tubercles of A. shandikovi n. sp. is hypothesised and discussed. Further deep-sea surveys are obviously needed to shed light on the behaviour and mode of locomotion of this species.

A New Species of Orobdella (Hirudinida: Arhynchobdellida: Orobdellidae) from Japan Reveals the Function of the Orobdella Gastroporal Duct.

A quadrannulate species of Orobdella, O. kanaekoikeae sp. nov., from the mountainous region of Shikoku, Japan is described. This new species is small with a body length of mature individuals reaching only ca. 5 cm. Phylogenetic analyses using nuclear 18S, histone H3, mitochondrial cytochrome c oxidase subunit I, tRNACys, tRNAMet, 12S rRNA, tRNAVal, 16S rRNA, tRNALeu, and NADH dehydrogenase subunit 1 markers showed that O. kanaekoikeae is a sister species of the quadrannulate small O. brachyepididymis. Phylogenetic relationships among populations of this new species were also estimated using mitochondrial DNA markers. Additionally, transmission electron micrographs of a capsule-like structure obtained from a post-copulatory individual revealed that the capsule contained spermatozoa, and was thus defined as the spermatophore. The gastroporal duct of Orobdella leeches is an accessory copulatory organ that receives a spermatophore during copulation.

New tentacled leech Ceratobdella quadricornuta n. g., n. sp. (Hirudinida: Piscicolidae) parasitic on the starry skate Raja georgiana Norman from the Scotia Sea, Antarctica.

A new fish leech Ceratobdella quadricornuta n. g., n. sp. (Hirudinida: Piscicolidae), a parasite of the Antarctic skate Raja georgiana Norman (Rajiformes: Rajidae) collected between the Falkland Islands and South Georgia Island in the Scotia Sea, is described and compared with related genera. Ceratobdella quadricornuta is characterised by an uncommon appearance of its anterior sucker bearing four well-developed tentacles and a unique combination of features of the reproductive and digestive systems: crop and intestine equally developed, posterior crop caeca separated; accessory glands, conductive tissue and external copulatory area lacking; common part of ejaculatory ducts (common atrium) voluminous and muscular, male copulatory bursa short, small ovisacs opening into female copulatory bursa (vagina).

Morphological and genetic variations of the freshwater leech, Hirudinaria spp., in Peninsular Malaysia.

In this study the genetic diversity of local freshwater leeches (Hirudinaria spp.) was inferred using mtDNA COI gene analysis and compared with the gross external variations of 26 freshwater leech specimens obtained from the wild and leech farms. Based on a neighbor-joining tree generated from 516 COI base sequences, four distinct clades of Hirudinaria were seen with interspecific genetic divergence in the range of 7.6-14.5%. The external morphological variations based on the presence of stripes, location of gonopores, and anus separated the samples into four morphologically distinct groups matching the four clades obtained from the molecular data. Two black stripes at the ventral region were observed only in specimens found clustered with clades that contained the GenBank-reported H. manillensis, whereas the brown or dark green coloration without stripes on the ventral region was seen in samples that clustered with H. javanica and H. bpling clades.

[Histological and histochemical studies on mouthpart of Whitmania pigra at different months age].

Mouthpart developmental histology of Whitmania pigra at different month of age were studied by paraffin section, HE staining combined alcian blue and periodic acid schifts reaction procedure (AB-PAS). The following results was obtained: Change ranges: oral width 0.6 mm (1-3 month), 1.2 mm (34 month); oral diameter 0.3 mm (1-3 month); 1.2 mm (34 month), the oral size reached maximum during 4-6 months and unchanged thereafter. Oral lip had a thin protective film located in the front of the mouthpart. The W. pigra possessed three jaws in oral cavity, the big one was in dorsum, the other two separated on both side of abdomen respectively. Jaws and muscular pharynx were interrelated closely. The jaws were composed by cuticle, epithelial layer, muscularis and jaw cavity from outside to inside. In the front of jaws had mastoid abdomen with function of secreting acidophilic granule from 2 month age. Oral cavity was composed by mucosa, submucosa and muscularis inside and outside. Oral cavity was rich of peristomial nerves. And pharynx was composed of mucosa, muscularis, adventitia from inside to outside. The folds height and width become heighten and thicken. Mucosa epithelium from complex flat epithelium changed into columnar epithelium, muscularis gradually developed into thickened along with growing. Muscular thickness reached maximum at 4 months. Mucous cells of W. pigra were classified into I-IV types based on different staining and two mainly morphological shapes (Tubular, Pear-shaped). Jaws, oral cavity, pharynx by AB-PAS staining showed little changes at different month of age. Mucous cells were few at 1 month age, and type II cells were increased rapidly in 2-3 month age in oral lip. Oral cavity contains more mucous gland cells type I. Under the muscularis there were connective tissues which distributed a few of mucous cells type II.

Terrestrial predatory leeches of the genus Orobdella (Hirudinea: Erpobdelliformes: Orobdellidae) endemic to the Southern Russian Far East: a new species of the genus from Primorsky Krai, Russia.

A quadrannulate species, Orobdella ganini sp. nov., is described from the Lazovsky Nature Reserve in Primorsky Krai, the Southern Russian Far East, Russia. Morphological features of O. ghilarovi Nakano & Prozorova, 2019 from the reserve are also provided leading to an amendment of the species diagnosis. Maximum likelihood and Bayesian inference phylogenetic analyses, which were performed using nuclear 18S rRNA, 28S rRNA, and histone H3, and mitochondrial cytochrome c oxidase subunit I, tRNACys, tRNAMet, 12S rRNA, tRNAVal, 16S rRNA, tRNALeu and NADH dehydrogenase subunit 1 markers, show that O. ganini sp. nov., O. ghilarovi and two species endemic to Hokkaido, Japan form a clade, with the new species sister to a lineage composed of the two Japanese species. A partial cytochrome c oxidase subunit I sequence obtained from a cocoon found in the Lazovsky Nature Reserve reveals that Orobdella leeches deposit cocoons somewhat similar to those deposited by terrestrial blood-sucking leeches of Haemadipsidae.

MOLECULAR PHYLOGENY OF THE LEECH GENUS PONTOBDELLA (HIRUDINIDA: PISCICOLIDAE) WITH NOTES ON PONTOBDELLA CALIFORNIANA AND PONTOBDELLA MACROTHELA.

Leech specimens of the genus Pontobdella (Hirudinida: Piscicolidae) were found off the coast of the state of Oaxaca (Pacific) as well as in Veracruz and Tabasco (Gulf of Mexico), Mexico. Based on the specimens collected in Oaxaca, a redescription of Pontobdella californiana is provided, with emphasis on the differences in the reproductive organs with the original description of the species. In addition, leech cocoons assigned to P. californiana were found attached to items hauled by gillnets and studied using scanning electron microscopy and molecular approaches. Samples of Pontobdella macrothela were found in both Pacific and Atlantic oceans, representing new geographic records. The phylogenetic position of P. californiana is investigated for the first time, and with the addition of Mexican samples of both species, the phylogenetic relationships within Pontobdella are reinvestigated. Parsimony and maximum-likelihood phylogenetic analysis were based on mitochondrial (cytochrome oxidase subunit I [COI] and 12S rRNA) and nuclear (18S rRNA and 28S rRNA) DNA sequences. Based on our results, we confirm the monophyly of Pontobdella and the pantropical distribution of P. macrothela with a new record in the Tropical Eastern Pacific.

Population variation and individual maximum size in two leech populations: energy extraction from cannibalism or niche widening?

The theory of cannibal dynamics predicts a link between population dynamics and individual life history. In particular, increased individual growth has, in both modeling and empirical studies, been shown to result from a destabilization of population dynamics. We used data from a long-term study of the dynamics of two leech (Erpobdella octoculata) populations to test the hypothesis that maximum size should be higher in a cycling population; one of the study populations exhibited a delayed feedback cycle while the other population showed no sign of cyclicity. A hump-shaped relationship between individual mass of 1-year-old leeches and offspring density the previous year was present in both populations. As predicted from the theory, the maximum mass of individuals was much larger in the fluctuating population. In contrast to predictions, the higher growth rate was not related to energy extraction from cannibalism. Instead, the higher individual mass is suggested to be due to increased availability of resources due to a niche widening with increased individual body mass. The larger individual mass in the fluctuating population was related to a stronger correlation between the densities of 1-year-old individuals and 2-year-old individuals the following year in this population. Although cannibalism was the major mechanism regulating population dynamics, its importance was negligible in terms of providing cannibalizing individuals with energy subsequently increasing their fecundity. Instead, the study identifies a need for theoretical and empirical studies on the largely unstudied interplay between ontogenetic niche shifts and cannibalistic population dynamics.

Erpobdellid leeches (Annelida, Clitellata, Hirudinida) from Tunisia: new records with the description of a new Trocheta species.

Up to now in Tunisia, freshwater Hirudinida are represented by two mainly haematophagous families: Hirudinidae and Glossiphonidae, and a predatory one: the family Erpobdellidae. The present study provides new information on the diversity and taxonomy of erpobdellid leeches. Identification was based, in addition to morphological data, on the length of sperm ducts and the lengths of ovisacs in relation to the neurosomite (ns) and on the shape and size of the male atrium. Five taxons are found. Two subspecies are reported for the first time in the country: Dina punctata punctata Johansson, 1927 and Dina punctata maroccana Nesemann and Neubert, 1994. Tunisian populations of two species, Erpobdella testacea (Savigny, 1820) and Trocheta africana Nesemann and Neubert, 1994, are described, with records of new localities. The new Trocheta tunisiana n. sp. is discovered and described in detail. Trocheta species live in springs in elevated areas while Erpobdella seem to prefer low altitude reservoirs. A comprehensive comparison of the three genera is presented. The disparity between the actual systematics and phylogeny is discussed. This study gives also a detailed distribution of the five species in the north of Tunisia with notes on ecological preference of the genus Dina. Finally a key for the determination of freshwater erpobdellid species from Tunisia is proposed.

A new species of Helobdella (Hirudinida: Glossiphoniidae) from Oregon, USA.

Helobdella bowermani n. sp. is described from specimens collected in fine sediment of open water benthos of Upper Klamath Lake, Klamath County, Oregon. The new species has pale yellow/buff coloration with scattered chromatophore blotches throughout the dorsal surface, lateral extensions or papillae only on the a2 annulus, dorsal medial row of papillae with small papilla on al and larger papillae on a2 and a3, and a small oval scute (rarely triangular). Helobdella bowermani n. sp. is morphologically similar to Helobdella atli and Helobdella simplex. Molecular comparison of CO-I sequence data from H. bowermani n. sp. revealed differences of 10.6/--10.8% with Helobdella californica, differences of 12.2%-13.7% with H. atli, and differences of 12.7%-13.2% with H. simplex.

Molecular phylogeny of the New World bloodfeeding leeches of the genus Haementeria and reconsideration of the biannulate genus Oligobdella.

The phylogenetic relationships of species of the New World bloodfeeding genus Haementeria were investigated for the first time. The analysis included five molecular markers. The mitochondrial COI, 12S and ND1 as well as the nuclear 28S and ITS. The evolutionary history of the group was investigated through Maximum Parsimony and Bayesian Inference. Both phylogenetic methods resulted in highly congruent hypotheses. The correlation between the phylogeny and morphological traits such as eyespot number, annulation, Lang's organs, salivary glands, bacteriomes and reproductive organs is discussed. Restricted to Haementeria are Lang's organs, spherical bacteriomes and ovaries forming an anterior ring around the ventral nerve cord. In addition, Oligobdella brasilensis was formally transferred to Haementeria, providing additional arguments for the disposal of the genus Oligobdella. Haementeria gracilis is shown to be just a junior synonym of Haementeria depressa as suggested by previous authors. Finally, the geographical distribution of species of Haementeria was compared with that of other non-leech and leech taxa. Multiple events of South-North American interchange were proposed to explain the current geographical distribution of the species of Haementeria.