Phylogeny for species of Haemonchus (Nematoda: Trichostrongyloidea): considerations of their evolutionary history and global biogeography among Camelidae and Pecora (Artiodactyla)

Phylogenetic analysis of 25 morphological characters among the 12 species of Haemonchus resulted in 1 most parsimonious tree (60 steps; consistency index = 0.67, retention index = 0.80). Monophyly for Haemonchus was diagnosed by 3 unequivocal synapomorphies, including the asymmetric origin of the dorsal ray, relative size of the ventral rays, and the presence of a barb on each spicule tip. Species of Haemonchus have complex histories with respect to host and geographic associations: (1) origins in Africa with basal diversification in antelopes (H. krugeri, H. lawrencei, H. dinniki, H. horaki), (2) independent events of colonization for those species in Caprini and Bovinae (H. contortus, H. placei, H. bedfordi, H. similis), (3) colonization and development of core host associations within Camelidae (H. longistipes) and among Antilopinae, Tragelaphini, and Giraffidae (H. mitchelli, H. okapiae, H. vegliai), and (4) geographically widespread species that are represented only by those that have been translocated with domestic stock. The North American fauna is characterized by 3 introduced and exotic species, H. placei, H. contortus, H. similis, which emphasizes the importance of continued documentation of faunal diversity in the context of predictive foundations derived from phylogenetic studies. Satellite associations for species of Haemonchus, particularly among Cervidae and Camelidae in the Neotropics and Cervidae, Antilocapridae, and possibly wild Caprinae in the Nearctic, have been a consequence of introductions and exchange of parasites at historical interfaces for managed and natural ecosystems. Such distributions are emblematic of the overriding significance of anthropogenic factors as determinants of the global distributions for pathogenic parasites in domestic and wild ruminants.     

Haemonchus horaki n. sp. (Nematoda: Trichostrongyloidea) from the grey rhebuck Pelea capreolus in South Africa.

In the course of a revision of species of Haemonchus Cobb, 1898 (Nematoda), commonly referred to as large stomach worms and significant pathogens of ruminants, a new species was discovered in the grey rhebuck Pelea capreolus, and the bontebok Damaliscus pygarthus, in South Africa. The new species, Haemonchus horaki, was previously reported as a long-spicule form of H. contortus (Rudolphi, 1803) Ransom, 1911. The new species, compared with H. contortus, can be distinguished by significantly longer spicules (555-615 microm vs. 383-475 microm); a synlophe with fewer ridges (26 vs. 30 in the region of the posterior part of the esophagus) that extend more posteriorly (within 1 mm of the copulatory bursa in males and postvulvar in females, vs. 2/3 to 3/4 of prebursal and prevulvar lengths); and an asymmetrical dorsal lobe with a long dorsal ray divided for more than half of its length, forming 2 branches of unequal length (vs. a dorsal ray divided for less than half of its length and forming 2 equal branches in H. contortus).     

Two new species of Nippostrongylinae (Nematoda,Trichostrongylina) parasites of Cricetomys gambianus and Arvicanthis niloticus (Muridae) from Senegal

Two new Nippostrongylinae (Heligmosomoidea, Heligmonellidae) originating from Senegal are described. Heligmonina bioccai n. sp., a parasite of Cricetomys gambianus (Cricetomyinae) found in the surroundings of Dakar and Neoheligmonella bai n. sp., a parasite of Arvicanthis niloticus (Murinae) from the Province of Richard Toll. H. bioccai n. sp. is related to H. hybomysi (Durette-Desset, 1966) a parasite of Hybomys univittatus from the Central African Republic by some characteristics of the caudal bursa and of the synlophe. They are the only two species with the same pattern of caudal bursa: type 1-3-1 for the right lobe, 2-3 for the left lobe, and with the same number and disposition of the cuticular ridges at mid-body in the female. The two species are differentiated by the size (three times smaller in H. hybomysi), the ratio of spicule length on body length (7.6% versus 17% in H. hybomysi) and by a different synlophe in male and posterior part of female. N. bai n. sp. is differentiated from the closely related species N. dielmensis Diouf, Ba and Durette-Desset, 1997, also a parasite of Arvicanthis niloticus from Senegal by rays 8 arising asymmetrically on the dorsal ray and by the deirids situated at the same level as the excretory pore.     

Ashworthius Patriciapilittae n. sp. (Trichostrongyloidea: Haemonchinae), an abomasal nematode in Odocoileus virginianus from Costa Rica,and a new record for species of the genus in the Western Hemisphere

A species of Ashworthius is reported for the first time in the Western Hemisphere, and A. patriciapilittae n. sp. is described on the basis of specimens in white-tailed deer Odocoileus virginianus from Costa Rica. Among 8 known species, A. patriciapilittae is morphologically similar to A. tuyenquangi in red muntjac Muntjacas muntjak from northern Vietnam. The synlophe in A. patriciapilittae is composed of 26 ridges in the cervical zone and is continuous to the caudal extremity in males and females. Males are characterized by a complex dorsal ray and narrow trifurcate spicules (351-356 microm long) lacking an "eyelet." with dissimilar ventral and dorsal processes; the gubernaculum is 45-48% of the spicule length. Females have a prominent linguiform flap at the vulva and large eggs (108-142 microm long). The presence of A. patriciapilittae in Costa Rica is examined in the context of competing hypotheses for cospeciation or contemporary host-switching in cervids: either A. patriciapilittae is a component of an endemic Central and South American fauna that has diversified through coevolution of Ashworthius and cervid hosts or it has been introduced. Among haemonchines in the Western Hemisphere, specimens of A. patriciapilittae may be confused with 3 species of Haemonchus, including H. contortus, H. placei, and H. similis, that occur in both domestic and wild ruminants. Discovery of A. patriciapilittae emphasizes the continued need for survey and inventory to define the structure and distribution of parasite faunas in wild and domestic ruminants from the Nearctic and Neotropical regions.     

Rhabdochona guerreroensis n. sp. (Nematoda: Rhabdochonidae) from the intestine of the gobiid Sicydium multipunctatum from fresh waters in Mexico

Rhabdochona guerreroensis n. sp. is described on the basis of specimens recovered from the intestine of Sicydium multipunctatum (Regan) (Gobiidae, Perciformes) from 2 localities in Mexico. This species is characterized by 12 teeth in the prostom (occasionally 11), asymmetrical numbers of postanal papillae, a broad distal tip of the larger (left) spicule with a small bifurcation covered by narrow cuticular membrane, a smaller (right) spicule with a dorsal barb on its distal tip, and filamented eggs.     

New species of Rhabdochona Railliet, 1916 (Nemata: Rhabdochonidae) from Rainbow Trout in California Streams

Three new species of Rhabdochona Railliet, 1916 are described and illustrated from Salmo gairdneri Richardson (rainbow trout) in freshwater streams in California: Rhabdochona californiemis n. sp., R. paxmani n. sp., and R. satmonis n. sp. Rhabdochona californiensis n. sp. is characterized by 14 anteriorly directed teeth in the prostome, egg devoid of filaments or floats, male and female tail terminus with a single mucro, left (long) spicule slender with a moderate distended podoid terminal end, spicular ratio 1:3.8. Rhabdochona paxmani n. sp. is characterized by 10 teeth in the prostome, eggs with polar floats, left (long) spicule slender with podoid terminus distended and having a minute subterminal spine; right spicule with prominent gorgeret (barb), spicular ratio 1:4.3, male and female tail terminus with a cuticular conical rounded short projection. Rhabdochona salmoni, n. sp. is characterized by 10 teeth anteriorly directed in the prostome, eggs with polar floats, left spicule slender with a distended podoid terminus; right spicule with a sharply indented gorgeret, spicular ratio 1:4.3, male and female tail terminus with a conical or rounded tip.     

A new Heligmonellid (Nematoda: Heligmonellidae) from Oecomys mamorae (Rodentia: Sigmodontinae) in the pantanal and new data on the synlophe of Guerrerostrongylus zetta from the Atlantic Forest, Brazil

A new species of Heligmonellidae nematode, Guerrerostrongylus gomesae n. sp., is described from specimens collected from the small intestine of the rodent Oecomys mamorae Thomas, 1906 in the Brazilian Pantanal. It differs from the 2 other species of the genus by the number of ridges in the synlophe 35-46 and 40-48 at the midbody in the male and female, respectively, by rays 8 arising at midlength of the dorsal trunk, ending near the margin of the caudal bursa, and the dorsal ray divided at the second-third part into 2 branches, each branch divided into 2 subequal subbranches. In addition, specimens of Guerrerostrongylus zetta Travassos, 1937 collected in Oligoryzomys nigripes Olfers, 1818 contain synlophe with 36-42 cuticular ridges in males and 38-42 in females at the midbody. By the characteristics of the synlophe and caudal bursa, Gerrerostrongylus gomesae n. sp. is considered a new species. We suggest that the number of cuticular ridges for this genus broadens the range of the cuticular ridges to at least 35 at midbody.     

A new rhabdochonid from the blue striped chub Sectator ocyurus (Osteichthyes: Kyphosidae) in Chamela Bay, Mexico

Megachona chamelensis n. gen., n. sp. is described from the intestinal cecae of blue striped chub Sectator ocyurus (Kyphosidae, Perciformes), from Chamela Bay, Mexico. Megachona n. gen. most closely resembles Beaninema Caspeta-Mandujano, Moravec, and Salgado-Maldonado, 2001; Fellicola Petter and K?ie, 1993; and Rhabdochona Railliet, 1916. The main characters that distinguish the new genus from all other rhabdochonids include a longer than wide funnel-shaped prostom and cuticular longitudinal ridges of prostom forming anteriorly subterminal massive toothlike structures followed posteriorly by irregularly arranged smaller teeth. This finding brings the total number of genera of Rhabdochonidae of marine fish in Mexico to 2. The new species is characterized by having a smaller number of cuticular longitudinal ridges in the male prostom than in the female prostom, forming massive toothlike structures in its subterminal portion, followed by more minute teeth in the female than in the male, a slender tail end with a broad tip, the distal part of the left spicule with a lanceolate end, a straight right spicule without a dorsal barb, 1 pair of precloacal and 3 pairs of postcloacal papillae, and a smooth egg surface.     

2 new species of Stilestrongylus (Nematoda: Heligmonellidae) parasites of Peromyscus (Rodentia: Cricetidae) from Mexico

Stilestrongylus peromysci n. sp. collected from Peromyscus difficilis (Hidalgo state, México), differs from other species in the genus in number of the spines (30) in the synlophe (both sexes) and because the eighth ray arises from the root of the ninth ray; S. hidalguensis n. sp. parasitised Peromyscus sp. and differs from all other congeneric species in the presence of 24 spines in the male synlophe and in the arrangement of the bursal rays (2-2-1 in the right lobe and 2-3 in the left lobe). A key to the species of Stilestrongylus is provided.     

A new angiostrongylid (Nematoda) species from the pulmonary arteries of Akodon azarae (Rodentia: Cricetidae) in Argentina

Angiostrongylus morerai n. sp. (Nematoda: Angiostrongylidae) is described from the pulmonary arteries of Azara's grass mouse Akodon azarae (Rodentia: Cricetidae) in Argentina. It is distinguished from its congeners principally by the morphology of the dorsal ray, which is as long, or longer, than the externodorsals and has 2 long branches; the spicule lengths are also greater (400-465 microm). This is the first record of a metastrongyloid from sigmodontine rodents in Argentina.     

A preliminary study of the effect of microclimate on third-stage larvae of Haemonchus contortus and Haemonchus placei on irrigated pasture.

Assessments were made on the influence of several microclimatic variables on the availability of third-stage larvae of Haemonchus contortus and Haemonchus placei on four strata of irrigated Kikuyu pasture. Three replicates of these pasture samples were collected on 18 sample days over 12 months and the log10 mean counts of the larvae recovered were analysed by a step-wise regression model. Predictors for the log counts of the four strata for the two nematode species included relative humidity, illumination, air temperature and windspeed. The effect of air temperature on larvae of both Haemonchus species was similar; as air temperature increased, the number of larvae on pasture increased. The inverse was true for windspeed; as windspeed increased larval counts decreased. For H. contortus, relative humidity increased as the number of larvae increased on all strata except upper herbage. The R2 values ranged from 0.11 to 0.21 for H. contortus and from 0.04 to 0.12 for H. placei. Under the conditions of this study, only 21% of the effect on H. contortus and 12% on H. placei third-stage larvae on pasture can be explained by microclimatic conditions.     

Genetic diversity patterns of Haemonchus placei and Haemonchus contortus populations isolated from domestic ruminants in Brazil

Parasitic nematodes of the genus Haemonchus infect a range of ruminant hosts and are of major veterinary and economic importance. In this study, the genetic variability of seven isolates of Haemonchus placei and Haemonchus contortus was evaluated using the mitochondrial gene cytochrome oxidase subunit I and the nuclear gene b-tubulin isotype 1. A total of 156 specimens were obtained from cattle, sheep, goat and buffalo herds raised on commercial properties from the southern and southeastern regions of Brazil and identified to the species level by sequencing of the nuclear internal transcribed spacer 2. Thirty-four percent of the specimens were identified as H. placei and 66% as H. contortus. Cattle were the preferred hosts for H. placei, whereas H. contortus was most frequent in the other three ruminant species. Analysis of genetic differentiation between isolates revealed that high rates of gene flow are operating among populations of both nematode species, including among those from different ruminant host species. Populations of H. placei were less polymorphic and presented a lower frequency of single nucleotide polymorphisms associated with benzimidazole resistance compared with H. contortus. In line with the low amount of genetic structure observed among isolates, alleles of b-tubulin 1 associated with benzimidazole resistance were present at relatively high frequencies of 5–20% in isolates of H. contortus from farms that never used this class of anthelmintic. The results presented here are consistent with the hypothesis of multiple origins of alleles associated with benzimidazole resistance, with the trade of animals among properties acting as the main factor promoting the spread of anthelmintic resistance.     

Synlophe patterns of the Haemonchinae of ruminants (Nematoda: Trichostrongyloidea)

The pattern of longitudinal ridges (synlophe) on the external cuticular surface of trichostrongylid nematodes has been shown to be of value for distinguishing species and determining relationships among higher taxa. In the process of studying Mecistocirrus digitatus, the large stomach worm of bovids of Asia that has been imported and established in the Americas, we observed remarkably similar synlophe patterns to those described for 3 species of Haemonchus and to those we examined in a species of Ashworthius. In all 3 genera, the synlophe is absent from the posterior part of the body. Only in Haemonchus does the synlophe extend beyond midbody. In both M. digitatus and Ashworthius sidemi, the synlophe extends posteriorly only about 1/4 of body length. In all 3 genera, the synlophe consists of about 30 ridges in the region of the esophagus with variation among species in specific areas, including additional pairs of subventral and subdorsal ridges and different lengths of sublateral ridges. This information is useful for identifying species and determining relationships among these large stomach worm parasites of cattle, sheep, goats, and farmed and wild cervids.     

Oswaldofiaria chabaudi n. sp. (Nematoda: Onchocercidae) from a South American tropidurid lizard (Squamata: Iguania) with an update on Oswaldofilariinae

A new species of Oswaldofilaria is described from Tropidurus torquatus (Tropiduridae: Iguania); its prevalence at the rocky study area at Juiz de Fora, Minas Gerais, Brazil, was approximately 30% and its mean intensity 3.13 +/- 2.51. Oswaldofilaria chaboudi n. sp. is distinct from the thirteen Oswaldofilaria species known in Australia, Africa and South-America in having the following characteristics: oesophagus medium-sized, left spicule 1 mm long and high spicular ratio (about 5), tail extremity ornated in both sexes with a bifurcated projection, and tooth-like structures near phasmids in the female. A long left spicule and high spicular ratio are convergent derived characters also found in a parasite of Australian crocodilians, O. kanbaya, and in several species of the closely related genus Befilaria, such as the Central American B. puertoricensis from polychrotids. Oswaldofilaria in South America is represented by eight species. Within these, a primitive group that is parasitic in Iguanidae, Polychrotidae (Iguania) and Crocodylidae and that possesses a long oesophagus is recognised, together with two distinct derived lines: three species with numerous, aligned precloacal papillae, parasitic in Teiidae (Laterato) and Scincidae (Scincomorpha), and O. chabaudi n. sp., in which this character is absent. Tropidurids (Tropiduris and Plica) had previously been reported in the host range of two oswaldofilarine genera, Oswaldofilaria and Piratuba, and their parasites assigned to known species described from other groups of lizards.     

Description of a new ascarid species in elasmobranchs from Taiwan Strait

A new ascarid of elasmobranchs, Terranova amoyensis sp. n., is described from the intestine of the red stringray, Dasyatis akajei (Müller and Henle), from Taiwan Strait. This is the second report from this genus with a gubernaculum in fish. The new species differs from its congeners mainly in the following combination of characters: the 3 lips are unequal in size and different in shape, i.e., the subventral lips are asymmetric bilaterally and larger than the dorsal lip; the latter lip is bilaterally symmetrical. The ventriculus is spherical, and the cecum is short relative to the esophagus. Spicules are unequal in size, 1.48 mm long for the right spicule and 1.34 mm for the left spicule, or 4.3 and 3.9% of body length, respectively. Nineteen pairs of caudal sessile papillae (excluding phasmids) are present, of which 13 pairs are precloacal; pairs 14 and 15 lie close together on either side of the cloaca, composing ad-cloacal papillae (the pair near the tail end are twins). The remaining 4 pairs of postcloacal papillae form a group near the tail tip (pair 18 also twins and near the phasmids). The gubernaculum is I-shaped. The excretory pore is located on top of a coniform prominence whose location is just behind or between the bases of the 2 subventral lips. The vulva is prominent at one-third of the anterior part of the body; the distance from the vulva opening to the anterior body end is 17.4 mm (13.61-21.41), 26.8% (25.14-28.93%) of the body length.     

Effect of desiccation on the survival of infective Haemonchus contorus larvae under laboratory conditions.

When stored in water at 4 and 20 C, respectively, 42 and 36% of free 3rd-stage, infective larvae of Haemonchus contortus were alive after 256 days. When stored at -95 C, 73% of the free, desiccated larvae died during the 1st half hour and 80% during the 1st half day; thereafter no more died for 255 days, the duration of the experiment. Desiccation protected the larvae against death on storage at temperature below freezing, but it was harmful at temperatures above freezing. H. contortus larvae do not withstand a single episode of desiccation as well as Trichostrongylus colubrformis larvae.     

Heliconema minnanensis n. sp. (Physalopteroidae: Physalopteridae) and Raphidascaris trichiuri (Yin and Zhang) n. comb. (Ascaridoidea: Anisakidae) in marine fishes.

Heliconema minnanensis n. sp. is described from the Chiloscyllium plagiosum south of the Minnan-Taiwan Bank Fishing Ground, Taiwan Strait. It is characterized by having the following combination of features. There are no longitudinal ridges in the posterior part of the body; the male has 4 pairs of precloacal papillae and 6-7 pairs of postcloacal papillae. The right spicule averages 0.2 mm long (1.1% of body length), and the left spicule averages 1.2 mm long (5.6% of body length), making an average spicule ratio of 1:5.2. The female has a vulva located on the left side of a thick membrane and 56-65% of the body length from the anterior end. Raphidascaris trichiuri (Yin and Zhang, 1983) comb. n., known previously from males only, is transferred from Cloeoascaris and redescribed, including material of both sexes from Muraenesox cinereus from the type locality.     

Neoheligmonella acomysi n. sp. (Trichostrongyloidea,Nippostrongylinae), parasite d'Acomys dimidiatus Muridae de Somalie

Résumé Neoheligmonella acomysi n. sp., parasite d'Acomys dimidiatus en Somalie est proche de N. houini Durette-Desset, 1970, de N. pseudospira Durette-Desset, 1970, toutes deux parasites d'Arvicanthis abyssinicus en Ethiopie, et de N. dossoi Durette-Desset & Cassone, 1986, parasite d'Uranomys ruddi en Côte d'Ivoire. Il se sépare de ces trois espèces par de longues côtes ventrales, une côte dorsale divisée dans son tiers moyen, des spicules à pointe épaisse et un synlophe de sept et non six arêtes ventrales.

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Neoheligmonella acomysi n. sp., a parasite of Acomys dimidiatus in Somalia, is closely related to N. houini Durette-Desset, 1970 and N. pseudospira Durette-Desset, 1970, both parasites of Arvicanthis abyssinicus in Ethiopia, and to N. dossoi Durette-Desset & Cassone, 1986, a parasite of Uranomys ruddi in the Ivory Coast. It is differentiated from those species by its long ventral rays, the division of the dorsal ray in the middle third, the thickness of the tips of the spicule and a synlophe with seven ventral longitudinal cuticular ridges.

     

A quantitative histological study of the aortic nerve and the aortic body in the buffalo (Bubalus bubalis)

In the buffalo, the left aortic nerve ramifies in the periarterial connective tissue between the ventral surface of the aortic arch and the truncus pulmonalis. The right aortic nerve ramifies over the dorsal and right aspects of the aorta ascendens near its origin. The histograms of myelinated fibres of both left and right aortic nerve are distinctly unimodal with peak around 4-6 micron (64.2-67.8%). The left aortic body is situated in the periarterial connective tissue between the ventral surface of the aortic arch and the truncus pulmonalis, while the right aortic body is located in the tunica adventitia of the dorsal and right aspects of the aorta ascendens near its origin. The greatest sagittal section area of the left aortic body is 0.102 +/- 0.009 mm2 and that of the right aortic body is 0.041 +/- 0.002 mm2. The organ is highly vascular. The mean size of the glomus cells from the left aortic body is 7.68 +/- 0.9 micron x 9.37 +/- 0.13 micron (short diameter x long diameter), whereas the corresponding value for the right aortic body is 7.84 +/- 0.14 micron x 9.86 +/- 0.21 micron; and their density values are (11,417 +/- 301.7)/mm2 and (9,839 +/- 213.3)/mm2 respectively.     

Tadaridanema delicatus (Schwartz, 1927) n. gen., n. comb. (Trichostrongylina: Molineidae) parasite of Molossidae bats

On the basis of the revision of the type material of Anoplostrongylus delicatus Schwartz, 1927, and new specimens collected from Tadarida brasiliensis mexicana (Saussure, 1860) in 4 arid localities from Mexico, we describe a new genus (Tadaridanema n. gen.), to which A. delicatus is transferred (as Tadaridanema delicatus (Schwartz, 1927) n. gen., n. comb.). This new genus differs from all other genera included in Anoplostrongylinae by having ray 2 larger than ray 3. In addition, T. delicatus can be differentiated from the type species of Anoplostrongylus (Anoplostrongylus paradoxus (Travassos, 1918)) because it possess vestibular branches equal in length, cephalic inflation divided into 2 regions, and synlophe with many small ridges at the midbody level, whereas in T. delicatus, vestibular branches are equal in size, cephalic inflation is simple in structure, and the synlophe has only 2 well-developed dorsal cuticular ridges.