Common Atrium Research Articles

Common Atrium Concurrent with Atrioventricular Septal Defect: A Case Report

Common atrium accounts for 0.5% to 1% of congenital heart diseases. It is characterized by the atria septum's complete absence and atrioventricular canal defect. It may occur as an isolated malformation or associated with other extracardiac anomalies. Untreated cases are at risk of developing pulmonary hypertension. We present a case of an 18-month-old female baby with a recurrent chest infection, central cyanosis, and echocardiographic features of the common atrium concurrent with atrioventricular canal defect and features of pulmonary hypertension.

Enhancing the Classification of Congenital Heart Defects for Outcome Association Studies in Birth Defects Registries.

Traditional strategies for grouping congenital heart defects (CHDs) using birth defect registry data do not adequately address differences in expected clinical consequences between different combinations of CHDs. We report a lesion-specific classification system for birth defect registry-based outcome studies. For Core Cardiac Lesion Outcome Classifications (C-CLOC) groups, common CHDs expected to have reasonable clinical homogeneity were defined. Criteria based on combinations of Centers for Disease and Control-modified British Pediatric Association (BPA) codes were defined for each C-CLOC group. To demonstrate proof of concept and retention of reasonable case counts within C-CLOC groups, Texas Birth Defect Registry data (1999-2017 deliveries) were used to compare case counts and neonatal mortality between traditional vs. C-CLOC classification approaches. C-CLOC defined 59 CHD groups among 62,262 infants with CHDs. Classifying cases into the single, mutually exclusive C-CLOC group reflecting the highest complexity CHD present reduced case counts among lower complexity lesions (e.g., 86.5% of cases with a common atrium BPA code were reclassified to a higher complexity group for a co-occurring CHD). As expected, C-CLOC groups had retained larger sample sizes (i.e., representing presumably better-powered analytic groups) compared to cases with only one CHD code and no occurring CHDs. This new CHD classification system for investigators using birth defect registry data, C-CLOC, is expected to balance clinical outcome homogeneity in analytic groups while maintaining sufficiently large case counts within categories, thus improving power for CHD-specific outcome association comparisons. Future outcome studies utilizing C-CLOC-based classifications are planned.

Autonomous Fontan pump: Computational feasibility study

ObjectiveAfter Fontan palliation, patients with single-ventricle physiology are committed to chronic circulatory inefficiency for the duration of their lives. This is due in large part to the lack of a subpulmonary ventricle. A low-pressure rise cavopulmonary assist device can address the subpulmonary deficit and offset the Fontan paradox. We investigated the feasibility of a Fontan pump that is self-powered by tapping reserve pressure energy in the systemic arterial circulation. MethodsA double-inlet, double-outlet rotary pump was designed to augment Fontan flow through the total cavopulmonary connection. Pump power is supplied by a systemic arterial shunt and radial turbine, with a closed-loop shunt return to the common atrium (QP:QS 1:1). Computational fluid dynamic analysis and lumped parameter modeling of pump impact on the Fontan circulation was performed. ResultsFindings indicate that a pump that can augment all 4 limbs of total cavopulmonary connection flow (superior vena cava/inferior vena cava inflow; left pulmonary artery/right pulmonary artery outflow) using a systemic arterial shunt powered turbine at a predicted cavopulmonary pressure rise of +2.5 mm Hg. Systemic shunt flow is 1.43 lumped parameter model, 22% cardiac output. Systemic venous pressure is reduced by 1.4 mm Hg with improved ventricular preload and cardiac output. ConclusionsIt may be possible to tap reserve pressure energy in the systemic circulation to improve Fontan circulatory efficiency. Further studies are warranted to optimize, fabricate, and test pump designs for hydraulic performance and hemocompatibility. Potential benefits of an autonomous Fontan pump include durable physiologic shift toward biventricular health, freedom from external power, autoregulating function and exercise responsiveness, and improved quality and duration of life.

Intracerebral haemorrhage in a child with isolated levocardia, transposition of great arteries and common atrium. Rare Case Report

Background: Pediatric hemorrhagic stroke is rare and frequently associated with vascular lesions. Children with congenital heart diseases commonly present with ischemic stroke and rarely presenting with hemorrhagic stroke. Case presentation: We present a 9 years old girl with one day history of right sided weakness (hemiplegia) preceded by headache for two days. Radiological investigations were helpful in confirming left cerebral haemorrhage, transposition of great arteries, common atrium and situs inversus with levocardia in this patient. Laboratory investigations indicated high haemoglobin level and high red blood cell counts. We report a rare case of intracerebral haemorrhagic stroke in a child with multiple congenital malformations Conclusion: We concluded that high haemoglobin and red blood cell counts due to the recurrent hypoxia from deoxygenated blood and strenuous activities can occasionally cause spontaneous bleeding in visceral organs including the brain.

Two New Species of Freshwater Planarian (Platyhelminthes, Tricladida, Dugesiidae, Dugesia) from Southern China Exhibit Unusual Karyotypes, with a Discussion on Reproduction in Aneuploid Species

Two new species of the genus Dugesia from Southern China are described by applying an integrative approach, including morphological, karyological, histological, and molecular information. In the molecular phylogenetic tree, the two new species, Dugesia pendula Chen & Dong, sp. nov. and Dugesia musculosa Chen & Dong, sp. nov., fall into an Eastern Palearctic/Oriental clade and an Oriental/Australasian clade, respectively, while sharing only a rather distant relationship. The separate specific status of the two new species is supported also by their genetic distances. Dugesia pendula is characterized by the following features: symmetrical openings of the oviducts into the bursal canal, a duct between seminal vesicle and diaphragm, small diaphragm, dorsally located seminal vesicle, a penis papilla suspended from the dorsal wall of the male atrium, and mixoploid karyotype with diploid complements of 2n=2x=14+0−1 B-chromosome and triploid complements of 2n=3x=21+0−1 B-chromosome, with all chromosomes being metacentric. Dugesia musculosa is characterized by the following features: asymmetrical openings of the oviducts into the bursal canal; a ventrally displaced ejaculatory duct with a terminal opening; two diaphragms; a bursal canal provided with a strong, thick layer of circular muscle, which extends from the copulatory bursa to the common atrium and gonoduct; the left vas deferens opening at the midlateral wall of the seminal vesicle, while the right sperm duct opens at the dorsolateral wall of the seminal vesicle; and karyotype consisting of complicated diploid and aneuploid mosaicism, with diploid complements of 2n=2x=16 and 2n=2x=16−17th-18th, with all chromosomes being metacentric. The uncommon karyotypes, combined with the asexual reproduction of aneuploid animals, are evaluated in the context of the relationship between ploidy levels and reproductive modalities in the genus Dugesia.

Integrative description of a new species of Dugesia (Platyhelminthes, Tricladida, Dugesiidae) from Shennongjia, Central China.

A new species of the genus Dugesia (Platyhelminthes, Tricladida, Dugesiidae) from Xiangxi River, Shennongjia Forestry District, Hubei Province, China, is described on the basis of an integrative approach, involving morphology, and molecular systematics. The new species Dugesia saccaria A-T. Wang & Sluys, sp. nov. is characterized by the following features: a dumb-bell-shaped, muscularized hump located just anterior to the knee-shaped bend in the bursal canal; a ventrally displaced ejaculatory duct, which, however, opens terminally through the dorsal portion of the blunt tip of the penis papilla; a ventrally located seminal vesicle, giving rise to a vertically running duct that eventually curves downwards to communicate with the ejaculatory duct via a small diaphragm; oviducts opening asymmetrically into the dorsal portion of the common atrium and at the knee-shaped part of the bursal canal. The phylogenetic position of the new species was determined using four molecular markers (18S rDNA; ITS-1; 28S rDNA; COI), which suggested that it groups with other species of Dugesia from the Australasian and Oriental biogeographical regions.

Ablation of atrial flutter in a patient after Fontan procedure: a case report of challenging access to the common atrium

Abstract Background In patients with a total cavopulmonary connection in Fontan circulation, the access to the common atrium (CA) during a catheter ablation can be challenging, even in the presence of fenestration in an intra-atrial lateral tunnel (IALT). In our department, the fenestration is typically marked with metal clips (MCs). To the best of our knowledge, there is no previous report of balloonoplasty of clipped fenestration. Case summary A 19-year-old male with hypoplastic left heart syndrome (HLHS) was scheduled for catheter ablation of recurrent atrial tachycardia. He was diagnosed with HLHS prenatally and underwent a stepwise surgical palliation. Fontan circulation was completed with the creation of a fenestrated IALT. The fenestration was marked by four MCs. During the ablation procedure, the passage of the steerable sheath with mapping catheter to the CA was prevented by a small fenestration size and rigidness of the edges of the fenestration caused by the MCs. Multiple attempts to dilate the fenestration using a peripheric angioplasty balloon failed. Only angioplasty with the ‘balloon-against-dilator’ technique was finally successful. Activation map showed a counterclockwise atrial flutter in the CA; successful ablation was performed. Discussion We present a case of challenging access to the CA through a clipped fenestration in a polytetrafluoroethylene baffle for atrial tachycardia ablation. Even though a tunnel fenestration in Fontan patients facilitates access to the CA, the passage of a steerable introducer with a mapping catheter may be challenging due to diameter mismatch and the rigidity of its edges caused by MCs. The balloon-against-dilator technique might be helpful when conventional balloon angioplasty fails.

TAPVR: Molecular Pathways and Animal Models.

The venous pole of the heart where the pulmonary veins will develop encompasses the sinus venosus and the atrium. In the fourth week of development, the sinus venosus consists of a left and a right part receiving blood from the common cardinal vein, the omphalomesenteric and umbilical veins. Asymmetrical expansion of the common atrium corresponds with a rightward shift of the connection of the sinus to the atrium. The right-sided part of the sinus venosus including its tributing cardinal veins enlarges to form the right superior and inferior vena cava that will incorporate into the right atrium. The left-sided part in human development largely obliterates and remodels to form the coronary sinus in adults. In approximately the same time window (4th-fifth weeks), a splanchnic vascular plexus surrounds the developing lung buds (putative lungs) with a twofold connection. Of note, during early developmental stages, the primary route of drainage from the pulmonary plexus is toward the systemic veins and not to the heart. After lumenization of the so-called mid-pharyngeal endothelial strand (MPES), the first anlage of the pulmonary vein, the common pulmonary vein can be observed in the dorsal mesocardium, and the primary route of drainage will gradually change toward a cardiac drainage. The splanchnic pulmonary venous connections with the systemic cardinal veins will gradually disappear during normal development. In case of absence or atresia of the MPES, the pulmonary-to-systemic connections will persist, clinically resulting in total anomalous pulmonary venous return (TAPVR). This chapter describes the developmental processes and molecular pathways underlying anomalous pulmonary venous connections.

SYSTEMATIC REVISION OF THE FISH BLOOD FLUKES WITH DIAGNOSES OF CHIMAEROHEMECIDAE YAMAGUTI, 1971, ACIPENSERICOLIDAE N. FAM., SANGUINICOLIDAE POCHE, 1926, ELOPICOLIDAE N. FAM., AND APOROCOTYLIDAE ODHNER, 1912.

We herein morphologically diagnose the 5 natural groups of fish blood flukes and name them. Species of Chimaerohemecidae Yamaguti, 1971 infect chimeras, sharks, and rays (Chondrichthyes) and have C-shaped lateral tegumental spines and a non-sinusoidal testis or lack spines and have a sinusoidal testis. Species of Acipensericolidae n. fam. infect sturgeons and paddlefish (Acipenseriformes) and have a robust, bowl-shaped, pedunculate anterior sucker, lateral tegumental spines that are spike-like (not C shaped), an inverse U-shaped intestine (anterior ceca absent) with posterior ceca terminating near the excretory bladder, 6 testes (inter-cecal ovoid or oblong, lacking deep lobes; including 1 post-ovarian testis), a Laurer's canal, and a dextral common genital pore. Species of Sanguinicolidae Poche, 1926 infect primarily later-branching freshwater ray-finned fishes (Teleostei) and have a diminutive anterior sucker, a medial esophageal swelling (pouch), short, radial ceca of approximately equal length or short anterior ceca plus an elongate, dendritic posterior cecum, testis with appendix-like lateral lobes, no Laurer's canal, and separate or common genital pores. Species of Elopicolidae n. fam. infect ladyfishes, tarpons, and catadromous eels (Elopomorpha) and have a robust, bowl-shaped, pedunculate anterior sucker, lateral tegumental spines that are spike-like (can be lost in adult), short or indistinct anterior ceca, posterior ceca that terminate at level of the testis(es), a single testis or 2 testes, a Laurer's canal present or absent, and a sinistral common genital pore and atrium. Species of Aporocotylidae Odhner, 1912 primarily infect later-branching marine and estuarine ray-finned fishes (Teleostei) and have a spheroid anterior sucker with concentric rows of circumferential spines or the spheroid anterior sucker is lost in adults or adults have a diminutive anterior sucker, a sinuous esophagus lacking a pouch, an X- or H-shaped intestine having 4 ceca, long anterior ceca (or secondarily lost), smooth posterior ceca that extend posteriad in parallel with respective body margin and terminate near the posterior body end, testis(es) that lack appendix-like lateral lobes, no Laurer's canal, and a sinistral common genital pore or separate genital pores that are sinistral. Our 28S phylogeny recovered the fish blood flukes as monophyletic and each of the morphologically diagnosed families as monophyletic and sister to the remaining blood flukes infecting turtles and homeotherms. Acipensericolidae was recovered sister to the clade comprising Chimaerohemecidae + Sanguinicolidae and Elopicolidae + Aporocotylidae. The branching order and interrelationships of these families remains unsettled perhaps because of low taxon sampling among non-aporocotylids and extinction of intermediate taxa.

Left Atrial Ligation in the Avian Embryo as a Model for Altered Hemodynamic Loading During Early Vascular Development.

Due to its four-chambered mature ventricular configuration, ease of culture, imaging access, and efficiency, the avian embryo is a preferred vertebrate animal model for studying cardiovascular development. Studies aiming to understand the normal development and congenital heart defect prognosis widely adopt this model. Microscopic surgical techniques are introduced to alter the normal mechanical loading patterns at a specific embryonic time point and track the downstream molecular and genetic cascade. The most common mechanical interventions are left vitelline vein ligation, conotruncal banding, and left atrial ligation (LAL), modulating the intramural vascular pressure and wall shear stress due to blood flow. LAL, particularly if performed in ovo, is the most challenging intervention, with very small sample yields due to the extremely fine sequential microsurgical operations. Despite its high risk, in ovo LAL is very valuable scientifically as it mimics hypoplastic left heart syndrome (HLHS) pathogenesis. HLHS is a clinically relevant, complex congenital heart disease observed in human newborns. A detailed protocol for in ovo LAL is documented in this paper. Briefly, fertilized avian embryos were incubated at 37.5 °C and 60% constant humidity typically until they reached Hamburger-Hamilton (HH) stages 20 to 21. The egg shells were cracked open, and the outer and inner membranes were removed. The embryo was gently rotated to expose the left atrial bulb of the common atrium. Pre-assembled micro-knots from 10-0 nylon sutures were gently positioned and tied around the left atrial bud. Finally, the embryo was returned to its original position, and LAL was completed. Normal and LAL-instrumented ventricles demonstrated statistically significant differences in tissue compaction. An efficient LAL model generation pipeline would contribute to studies focusing on synchronized mechanical and genetic manipulation during the embryonic development of cardiovascular components. Likewise, this model will provide a perturbed cell source for tissue culture research and vascular biology.

Ventriculoureteral shunt: Narrative review of contemporary cases and its historical role in the development of renal transplantation.

Ventriculo-ureteral (VU) shunting is a little-known method of managing hydrocephalus. This paper reviews contemporary uses of this shunting technique and describes its historical significance to the field of organ transplantation. The ureter may serve as a possible backup, or alternative, distal drainage site compared to the more common peritoneum, atrium, and pleural space. Sporadic contemporary uses of the VU shunt have been reported in unique situations, demonstrating a possible utility in modern neurosurgery. Interestingly, the VU shunt played an important role in the development of kidney transplantation. In the late 1940s and early 1950s, David Hume, a general surgery resident, and colleagues at the PBBH undertook a series of human kidney transplantations. Concurrently, Donald Matson, a pediatric neurosurgeon at Peter Bent Brigham, was utilizing the VU shunt in hydrocephalic patients. Dr. Matson's VU shunt technique involved total nephrectomy, and some of the kidneys harvested from Dr. Matson's were used by his general surgery colleagues in their transplantation trials. Although none of the transplanted kidneys from this series were successful, the transplant team in Boston, minus David Hume, went on to perform the world's first kidney transplant a few years later. This relatively unfamiliar procedure may be applicable to specific situations, and it is of historical importance to the field of transplantation.

Chamber formation and morphogenesis in the heart of goat embryos

To know the partitioning of atria and ventricles and to record the sequential events in development of heart at different stages of prenatal life, 12 goat embryos were collected from slaughterhouses of Mathura (Uttar Pradesh). The primitive tubular heart consisting of four cardiac chambers, converted into five cardiac chambers on 26 days goat embryos. At early stages of gestation, the lumen was comprised of endocardial cushions and A-V canal between the atrium and ventricle of tubular heart. The fusion of these endocardial cushions took place and they divided the A-V canal into right and left atrioventricular orifices (A-V canal) at 38 days embryos. At 23 to 38 days goat embryos, the common atrium was divided into right and left compartments by formation of septum primum and septum secundum. The ventricular septum grew as a crescentric plate, extended towards the endocardial cushions forming interventricular septum at 38 days embryos. The study concluded that the partitioning of tubular heart starts at 23 days embryos and formation of completely separated four chambered heart took place at 38 days embryos except for foramen ovale, which persists till birth.

A rare coexistence of common atrium, univentricular atrioventricular connection, total anomalous pulmonary venous connection, and aortic atresia in an asymptomatic teenage girl

A rare coexistence of common atrium, univentricular atrioventricular connection, total anomalous pulmonary venous connection, and aortic atresia in an asymptomatic teenage girl

Situs ambiguous with three chambered heart (single atrium), evaluation by four-dimensional X-strain color echocardiography – A case report

Situs ambiguous accounts for 4% of all congenital heart disease (CHD) and has an incidence of 1:10,000 new born births. To standardize the nomenclature for CHD, the international nomenclature society published a globally accepted nomenclature tree for CHD with the 11th Iteration of international classification of disease. According to this publication common atrium, single atrium and atrium communis are denoted as synonyms. The incidence of common atrium among atrial septal defect (ASD) patients is 3–4% only and thus denoting it to be a rare entity. We are presenting an exceedingly rare case of a patient of situs ambiguous, left isomerism, and single atrium with a cleft on the anterior mitral leaflet, evaluated comprehensively by four-dimensional X-strain color Doppler echocardiography.

Pentalogy of Cantrell.

Pentalogy of Cantrell.

Human phenotype ontology annotation and cluster analysis for pulmonary atresia to unravel clinical outcomes.

BackgroundPulmonary atresia (PA) is a heterogeneous congenital heart defect and ventricular septal defect (VSD) is the most vital factor for the conventional classification of PA patients. The simple dichotomy could not fully describe the cardiac morphologies and pathophysiology in such a complex disease. We utilized the Human Phenotype Ontology (HPO) database to explore the phenotypic patterns of PA and the phenotypic influence on prognosis.MethodsWe recruited 786 patients with diagnoses of PA between 2008 and 2016 at Fuwai Hospital. According to cardiovascular phenotypes of patients, we retrieved 52 HPO terms for further analyses. The patients were classified into three clusters based on unsupervised hierarchical clustering. We used Kaplan–Meier curves to estimate survival, the log-rank test to compare survival between clusters, and univariate and multivariate Cox proportional hazards regression modeling to investigate potential risk factors.ResultsAccording to HPO term distribution, we observed significant differences of morphological abnormalities in 3 clusters. We defined cluster 1 as being associated with Tetralogy of Fallot (TOF), VSD, right ventricular hypertrophy (RVH), and aortopulmonary collateral arteries (ACA). ACA was not included in the cluster classification because it was not an HPO term. Cluster 2 was associated with hypoplastic right heart (HRH), atrial septal defect (ASD) and tricuspid disease as the main morphological abnormalities. Cluster 3 presented higher frequency of single ventricle (SV), dextrocardia, and common atrium (CA). The mortality rate in cluster 1 was significantly lower than the rates in cluster 2 and 3 (p = 0.04). Multivariable analysis revealed that abnormal atrioventricular connection (AAC, p = 0.011) and persistent left superior vena cava (LSVC, p = 0.003) were associated with an increased risk of mortality.ConclusionsOur study reported a large cohort with clinical phenotypic, surgical strategy and long time follow-up. In addition, we provided a precise classification and successfully risk stratification for patients with PA.

A New-Onset Mass in the Right-Sided Atrium in a Child After Cardiac Surgery: Unravelling the Diagnosis

A 2-year-old girl (weight: 9 kg, height: 82 cm) underwent an intracardiac repair. Preoperative transthoracic echocardiography revealed situs solitus, levocardia, left atrial isomerism, common atrium due to a large atrial septal defect, absent coronary sinus, 2 separate atrioventricular valves with a trivial left atrioventricular valve regurgitation due to a cleft in the anterior leaflet, and a dilated right ventricle with flattening of the interventricular septum due to volume overload (Fig. 1).

An adult with left isomerism having an interrupted inferior vena cava and persistent left superior vena cava associated with partial atrioventricular canal defect and complete heart block — a case report

BackgroundPersistent left superior vena cava is a well-recognized thoracic venous abnormality, most of which do not present with any symptoms. Its opening into the left atrium is uncommonly encountered and, if present, is noted to be associated with various other complex intracardiac malformations, which further complicates its management. Herein, we highlight a case of an adult with persistent left superior vena cava with a spectrum of other cardiac anomalies rarely encountered with it, which was effectively managed by tailored surgical intervention.Case presentationA 26-year-old female on meticulous evaluation was found to have left isomerism with an interrupted inferior vena cava and hemiazygos continuing as a persistent left superior vena cava. It was also associated with common atrium, partial atrioventricular canal defect, and complete heart block. This complex array of anomalies was managed surgically. Common atrium was closed with atrial neo-septation using autologous pericardial patch tailored in a way, such that the persistent left superior vena cava drained into right atrium with left atrial appendage being on right side of neo-septum. Cleft in the left atrioventricular valve was also repaired. Despite preoperative complete heart block, the patient had an uneventful postoperative recovery and was in atrial fibrillation with controlled ventricular rate, thus precluding the need for permanent pacemaker implantation.ConclusionsA rare spectrum of adult congenital cyanotic heart disease was successfully managed with thorough preoperative evaluation and judicious intraoperative management. Surgical management should be tailored based on specific anatomy for reduction of morbidity and optimum results.

The first report of a parasitic 'turbellarian' from a cephalopod mollusc, with description of Octopoxenus antarcticus gen. nov., sp. nov. (Platyhelminthes: Fecampiida: Notenteridae).

Parasitic 'turbellarians' are known from various animals such as echinoderms, crustaceans, annelids, bivalve and gastropod molluscs. So far, however, no 'turbellarians' have been reported from cephalopods. In this paper we report a parasitic 'turbellarian' from the giant Antarctic octopus, Megaleledone setebos. We dissected two specimens of M. setebos caught in the Ross Sea (Antarctica) and found numerous worms in their intestine and liver. The worms were spherical or oblong and had two morphologically different poles. The frontal pole bears a small conical protrusion containing large elongated pear-shaped frontal glands and large polygonal cells. The ducts of the frontal glands open terminally to form the frontal organ. The caudal pole has an opening shaped as a folded tube connected by the genital pore with a common genital atrium, which continues into a canal with a muscular sheath. The worms were identified as 'turbellarians' from the family Notenteridae (Fecampiida). This family contains only one species, Notentera ivanovi, reported from the gut of a polychaete at the White Sea. The worms that we found in the gastrointestinal tract of the octopuses were morphologically similar to N. ivanovi but differed from it in several important respects. Phylogenetic analysis based on 28S rDNA gene showed that the newly found worm clustered together with other fecampiids in a highly supported clade and was closely related to N. ivanovi. On the basis of these morphological and molecular data, we described a new species, Octopoxenus antarcticus gen. nov., sp. nov. (Fecampiida: Notenteridae), establishing a new genus to accommodate it and provided an updated diagnosis of the family Notenteridae. This is the first report of a parasitic 'turbellarian' from a cephalopod mollusc.

Two new species of Dugesia (Platyhelminthes, Tricladida, Dugesiidae) from the tropical monsoon forest in southern China.

Two new species of the genus Dugesia (Platyhelminthes, Tricladida, Dugesiidae) from the tropical monsoon forest in southern China are described on the basis of an integrative taxonomic study involving morphology, karyology, histology, and molecular analyses. The new species Dugesiacircumcisa Chen & Dong, sp. nov. is characterised by asymmetrical openings of the oviducts; right vas deferens opening at anterior portion of the seminal vesicle and the left one opening at mid-lateral portion of the seminal vesicle; two diaphragms in ejaculatory duct, the latter being ventrally displaced and opening at the tip of the penis papilla, which is provided with a nozzle; wide duct connecting male atrium and common atrium; chromosome complement triploid with 24 metacentric chromosomes. The other new species, Dugesiaverrucula Chen & Dong, sp. nov., is characterised by the large size of the living worm, usually exceeding 3.5 cm in length; asymmetrical openings of the oviducts; subterminal opening of ventrally displaced ejaculatory duct; vasa deferentia symmetrically opening into the postero-lateral portion of the seminal vesicle; well-developed duct between the seminal vesicle and diaphragm; single dorsal bump near the root of the penis papilla; bursal canal with pleated wall and spacious posterior section; unstalked cocoons; chromosome complement diploid with 16 metacentric chromosomes. Inter-specific molecular distances and their positions in the phylogenetic tree reveal that D.circumcisa and D.verrucula are clearly separated from their congeners.