Evolutionary relationships of trichostrongyloid nematodes (Strongylida) inferred from ribosomal DNA sequence data

The evolutionary relationships of 21 species of trichostrongyloid nematodes were determined by use of sequence data of the second internal transcribed spacer of the ribosomal DNA aligned according to secondary structure information. Irrespective of the method of analysis used, the topologies of the phylogenetic trees derived from the molecular data differed with respect to all four hypotheses proposed previously for the evolutionary relationships of the different subfamilies within the Trichostrongylidae based on morphological data. Thus, the molecular data set did not resolve the conflict between the four previous proposals for the subfamilial relationships. Nonetheless, all trees derived from the molecular data showed strong support for the exclusion of the genera Filarinema and Amidostomum from the clade containing the species within the family Trichostrongylidae. This represents a major difference from the most recent proposal of the systematics of the Trichostrongyloidea in which these two genera were included within the Trichostrongylidae. Therefore, the molecular data support an earlier systematic framework in which Filarinema and Amidostomum were considered to be sister groups of the Trichostrongyloidea.     

Biomorphology of gastrointestinal nematodes of small ruminants

Under the term gastrointestinal nematodes are included numerous parasites species of livestock belonging to the families Strongyloididae (Strongyloides), Strongylidae (Chabertia, Oesophagostomum) Trichostrongylidae (Trichostrongylus, Ostertagia, Teladorsagia, Cooperia, Marshallagia), Molineidae (Nematodirus), Ancylostomatidae (Bunostomum) and Trichuridae (Trichuris). This paper reviews the biomorphology aspects of these parasites as well as the controversy by the taxonomists in the classifications.     

Obligate larval inhibition of Ostertagia gruehneri in Rangifer tarandus? Causes and consequences in an Arctic system

SUMMARY Larval inhibition is a common strategy of Trichostrongylidae nematodes that may increase survival of larvae during unfavourable periods and concentrate egg production when conditions are favourable for development and transmission. We investigated the propensity for larval inhibition in a population of Ostertagia gruehneri, the most common gastrointestinal Trichostrongylidae nematode of Rangifer tarandus. Initial experimental infections of 4 reindeer with O. gruehneri sourced from the Bathurst caribou herd in Arctic Canada suggested that the propensity for larval inhibition was 100%. In the summer of 2009 we infected 12 additional reindeer with the F1 and F2 generations of O. gruehneri sourced from the previously infected reindeer to further investigate the propensity of larval inhibition. The reindeer were divided into 2 groups and half were infected before the summer solstice (17 June) and half were infected after the solstice (16 July). Reindeer did not shed eggs until March 2010, i.e. 8 and 9 months post-infection. These results suggest obligate larval inhibition for at least 1 population of O. gruehneri, a phenomenon that has not been conclusively shown for any other trichostrongylid species. Obligate inhibition is likely to be an adaptation to both the Arctic environment and to a migratory host and may influence the ability of O. gruehneri to adapt to climate change.     

Helminths from introduced small mammals on Kerguelen, Crozet, and Amsterdam Islands (southern Indian Ocean).

Four monoxenous nematodes and 1 heteroxenous cestode were found in 4 species of introduced small mammals on isolated sub-Antarctic islands of the Indian Ocean. In the Kerguelen Archipelago, Syphacia obvelata, Passalurus ambiguus (Nematoda: Oxyuridae), and Rodentolepis straminea (Cestoda: Cyclophyllidae) were respectively found in the house mouse Mus musculus, the rabbit Oryctolagus cuniculus, and the black rat Rattus rattus. One accidental nematode, Trichostrongylus sp. (Nematoda: Trichostrongylidae), was also found in a black rat on Kerguelen. On Possession Island (Crozet Archipelago), R. straminea was present in the black rat. On Amsterdam Island, the brown rat R. norvegicus harbored 2 species, R. straminea and Nippostrongylus brasiliensis (Nematoda: Heligmonellidae). The small number of founder hosts and the depauperate terrestrial communities on these remote islands explain the low diversity in the helminth communities of these introduced mammals compared with continental populations.     

Effect of management interventions on the helminth parasites recovered from donkeys in South Africa

The helminth burdens and biodiversity of 9 randomly selected donkeys (Equus asinus) were examined after necropsy. Prior to necropsy, 8 of the animals were subjected to 1 of 3 management interventions (monthly fecal removal, prewinter moxidectin treatment, and a combination of both treatments) or a control for a 16-mo period. The remaining animal was killed earlier in the study. Quantitative samples were collected from the gastrointestinal tract for helminth recovery. The intestinal walls were examined with transmural illumination and thereafter digested with a HCl-peptic method for identification of the mucosal larval stages of cyathostomes. In this study, 37 helminth species belonging to the Ascarididae, Atractidae, Dictyocaulidae. Habronematidae, Onchocercidae, Oxyuridae, Strongylidae, and Trichostrongylidae, 1 cestode species of the Anoplocephalidae, and 1 trematode species in the Paramphistomatidae were recovered. In addition, 1 species of oestrid fly of the Gasterophilidae was identified. The results obtained in the present study support the application of several intervention methods to reduce the helminth burdens in donkeys.     

Species of cooperia ranson, 1907, (nematoda: trichostrongylidae), parasite of bovines in the State of S?o Paulo, Brasil (author's transl)

The authors verified for the first time in the State of S?o Paulo, Brazil, the presence of Cooperia curticei Giles, 1892 (Nematoda: Trichostrongylidae), parasitizing the small intestine of cattle at the Region of Alta Araraquarense.     

Nematode parasites from Burchell's zebras in South Africa

Twenty-five Burchell's zebras (Equus burchelli antiquorum) which were culled at monthly intervals in the Kruger National Park were examined for helminths. Twenty-nine species of nematodes belonging to the families Atractidae, Habronematidae, Onchocercidae, Oxyuridae, Strongylidae, Strongyloididae and Trichostrongylidae were recovered. The cyathostomes (small strongyles) most abundant were Cyathostomum tetracanthum, Cylicostephanus calicatus, Cylindropharynx sp. (? C. intermedia Theiler, 1923) and Cylicocyclus auriculatus. Cyathostomum alveatum, Cyathostomum montgomeryi, Cylicostephanus calicatus and Cylindropharynx sp. (? C. intermedia Theiler, 1923) were the most prevalent cyathostomes (small strongyles) while Craterostomum acuticaudatum was the most prevalent of the large strongyles. Of all the species recovered those most abundant were Crossocephalus viviparus and Probstmayria vivipara with intensities of 100 to 3,857,772 and 18,400 to 104,120,467, respectively. Four new species, two Triodontophorus spp. (Strongylidae) and two Habronema spp. (Habronematidae) were identified. Furthermore, this study furnishes a first report of Triodontophorus minor in zebras. The fourth stage cyathostomes as well as the adults of 11 of the 14 species were present in significantly greater intensities in autumn and winter.     

Physiopathological mechanisms of abomasal Trichostrongylidae infections in small ruminants

Abomasal Trichostrongylidae infections are still today an important cause of scarce performances in small ruminants, mainly when bred in extensive systems. Although morpho-biology, symptomatology, prophylaxis and therapy of these infections are well known, other, such as physiopathology, are less investigated. The aim of the present note is to review the more important physiopathogenetic mechanisms of abomasal Trichostrongylidae infections, with special emphasis to Haemonchus spp. and Teladorsagia spp. The parasitic anorexia due to the action of gastrin, the defects of digestion due to hypocloridia, the scarce intestinal absorption and anaemia caused by H. contortus are discussed. Furthermore, the effects of hypersensitivity sometimes caused by these abomasal nematodes are examined. A better knowledge of physiopathological mechanisms can represent an important factor to understand the relationships between host and parasite, useful to set up new diagnostic techniques or new therapeutic and prophylactic protocols for sanitary education and control plans of these important and widespread parasitic infections.     

A Megafauna’s Microfauna: Gastrointestinal Parasites of New Zealand’s Extinct Moa (Aves: Dinornithiformes)

We perform the first multidisciplinary study of parasites from an extinct megafaunal clade using coprolites from the New Zealand moa (Aves: Dinornithiformes). Ancient DNA and microscopic analyses of 84 coprolites deposited by four moa species (South Island giant moa, Dinornis robustus; little bush moa, Anomalopteryx didiformis; heavy-footed moa, Pachyornis elephantopus; and upland moa, Megalapteryx didinus) reveal an array of gastrointestinal parasites including coccidians (Cryptosporidium and members of the suborder Eimeriorina), nematodes (Heterakoidea, Trichostrongylidae, Trichinellidae) and a trematode (Echinostomida). Parasite eggs were most prevalent and diverse in coprolites from lowland sites, where multiple sympatric moa species occurred and host density was therefore probably higher. Morphological and phylogenetic evidence supports a possible vicariant Gondwanan origin for some of the moa parasites. The discovery of apparently host-specific parasite taxa suggests paleoparasitological studies of megafauna coprolites may provide useful case-studies of coextinction.     

Cooperia curticei Giles, 1892 (nematoda: trichostrongylidae) parasite of goats (capra hircus) in the State of S?o Paulo, Brazil (author's transl)

Cooperia curticei Giles, 1892 (Nematoda: Trichostrongylidae) is reported, for the first time, parasitizing the small intestine of goats (Capra hircus) in the State of S?o Paulo, Brazil. The animals came from the Region of the Alta Araraquarense. The spicules of the worms were well chitinized and measured, on the average, 153,68 micrometer with a standard error of 0,91 micrometer.     

Secretion and excretion of endogenously synthesized lipids by adult Haemonchus contortus in vitro

Results of the incorporation of carbon from 14C-glycerol into total, polar and nonpolar lipids in Haemonchus contortus (Nematoda: Trichostrongylidae) reveal that the radioactivity lost into the medium as lipids decreased during the first 3 h of incubation. This was followed by a drastic increase during the 4th h. Again, there was a decline by 75% during the 5th h. However, there was a slight increase in the nonpolar lipids during the 5th h.     

A cladistic analysis of the Trichostrongyloidea (Nematoda).

A morphologically based cladistic analysis of 40 genera included within the Trichostrongyloidea (Amidostomatidae, Dromaeostrongylidae and Trichostrongylidae) is proposed. Two genera were used as outgroups, one from the Strongylina and the other from the Ancylostomatina. Seven genera do not appear in the matrix because some significant morphological characters remain unknown for these genera. Nonetheless, except for Moguranema which is excluded as incertae sedis, a likely systematic position could be assigned to them based on the morphological characters that are known. The classification which best fits the consensus tree is composed of three families. In adding the genera not included in the tree, we obtain: (i) Trichostrongylidae with three sub-families, Amidostomatinae (four genera), Filarinematinae (three genera) and Trichostrongylinae (five genera); (ii) Haemonchidae with two sub-families: Ostertagiinae (eight genera) and Haemonchinae (five genera); (iii) Cooperiidae with three sub-families: Libyostrongylinae (five genera), Obeliscoidinae n. subfam. (five genera) and Cooperiinae (ten genera). Dromaeostrongylus and Ortleppstrongylus, whose females have a caudal spine, are excluded from the Trichostrongyloidea and are placed in the Molineoidea. The hypotheses relating to the evolutionary history of the Trichostrongyloidea are: the origin of the superfamily could have occurred during the upper Cretaceous period. The two most ancient sub-families (Amidostomatinae and Filarinematinae) would be of Gwondwanan origin and evolved during the Paleocene period within Neotropical aquatic birds and within the Australian marsupials. The Trichostrongylinae would have arisen during the Eocene period within birds and then adapted to diverse archaic mammals in the Neotropical region on one hand and in the Nearctic region, on the other hand and lastly adapted to the Lagomorpha and subsequently to the Ruminantia. In both families originating from the Trichostrongylidae, the adaptation to the Lagomorpha may have taken place during the Oligocene but in a different way. In the Haemonchidae, the Ostertagiinae may have passed directly from the Neartic region to Europe. In the Cooperiidae, the adaptation to Lagomorpha may have occurred either within the Libyostrongylinae which may have remained in the Ethiopian region since the Paleocene, or, more likely, by the passage of the Obeliscoidinae from the Nearctic region to the Asian, through the Bering strait. In all cases, the adaptation of the Trichostrongyloidea of Lagomorpha to Ruminants apparently took place during the Miocene, mainly in the Palearctic and the Ethiopian regions.     

Phylogeny of the Trichostrongylina (Nematoda) inferred from 28S rDNA sequences

We produced a molecular phylogeny of species within the order Strongylida (bursate nematodes) using the D1 and D2 domains of 28S rDNA, with 23 new sequences for each domain. A first analysis using Caenorhabditis elegans as an outgroup produced a tree with low resolution in which three taxa (Dictyocaulus filaria, Dictyocaulus noerneri, and Metastrongylus pudendotectus) showed highly divergent sequences. In a second analysis, these three species and C. elegans were removed and an Ancylostomatina, Bunostomum trigonocephalum, was chosen (on the basis of previous morphological analyses) as the outgroup for an analysis of the phylogenetic relationships between and within the Strongylina (strongyles) and Trichostrongylina (trichostrongyles). A very robust tree was obtained. The Trichostrongylina were monophyletic, but the Strongylina were paraphyletic, though this requires confirmation. Within the Trichostrongylina, the three superfamilies defined from morphological characters are confirmed, with the Trichostrongyloidea sister group to a clade including the Molineoidea and Heligmosomoidea. Within the Trichostrongyloidea, the Cooperiidae, Trichostrongylidae, and Haemonchidae were polytomous, the Haemonchinae were monophyletic, but the Ostertagiinae were paraphyletic. The sister-group relationships between Molineoidea and Heligmosomoidea were unsuspected from previous morphological analysis. No unequivocal morphological synapomorphy could be found for the grouping Molineoidea + Heligmosomoidea, but none was found which contradicted it.     

Species ofAnthostomella from Brunei, includingA. oblongata sp. nov.

Species ofAnthostomella reported from Brunei have been re-examined and the data is summarized in this paper. Five species are accepted, four are synonyms of previously described species and one is a new species. The new speciesAnthostomella oblongata is described and illustrated and a list ofAnthostomella species known from Brunei and a key to these species are provided.     

The genus Theissenia: T. pyrenocrata, T. cinerea sp. nov., and T. eurima sp. nov

The diagnosis of Theissenia is emended to include taxa that lack a definite central perithecial columella and taxa that feature ascospores with a germ slit. Theissenia cinerea is described as a new species that lacks a perithecial columella; T. eurima is described as a new species with ascospores having a germ slit. The type species, T. pyrenocrata, is redescribed and compared with the new species. The taxonomic position of Theissenia is discussed.     

Revision of genus Melamphaes (Melamphaidae). II. Multi-Raker species: M. polylepis, M. falsidicus sp. nova, M. pachystomus sp. nova, M. macrocephalus, M. leprus

The second part of the publication is devoted to the Melamphaes species (family Melamphaidae), which are characterized by 20 and more rakers on the first gill arch, by seven soft rays in the ventral fin, by absence of a temporal spine, by 14–15 rays in the pectoral fin, and by 11 abdominal vertebrae. M. polylepis is characterized by circumtropical range (Atlantic Ocean, Indian Ocean, western and central Pacific Ocean). Newly described species M. falsidicus is described from the northern Atlantic Ocean, where it was sampled between 34°N and 58°N. Before, this species was defined as M. microps. Another newly described species, M. pachystomus, is described along the Peruvian Coast. M. macrocephalus is redescribed. This species inhabits the eastern tropical Pacific Ocean (approximately between 30°N and 23°S). One of the studied specimens of M. macrocephalus was characterized by larger body size (SL = 128 mm) than was described before for this species. M. leprus is known currently by single findings from the eastern tropical Atlantic Ocean (between 11°N and 4°S). This species was also found in the samples obtain in the Gulf of Guinea.     

Chassalia magnificens sp. nov. and C. chrysoclada comb. nov. (Rubiaceae) from central Africa

Chassalia magnificens, a new species from the Albertine Rift in eastern Democratic Republic of Congo, is described and illustrated. The species is recognised inter alia by its large stipules and montane habitat. Chassalia chrysoclada is a new combination for a widespread, but hitherto overlooked, central African species originally described in the genus Psychotria. Chassalia chrysoclada is related to C. pteropetala (K. Schum.) Cheek but lacks the bicostate twigs and dorsally winged corolla lobes of that species.     

Substitution bias, rapid saturation, and the use of mtDNA for nematode systematics

Only relatively recently have researchers turned to molecular methods for nematode phylogeny reconstruction. Thus, we lack the extensive literature on evolutionary patterns and phylogenetic usefulness of different DNA regions for nematodes that exists for other taxa. Here, we examine the usefulness of mtDNA for nematode phylogeny reconstruction and provide data that can be used for a priori character weighting or for parameter specification in models of sequence evolution. We estimated the substitution pattern for the mitochondrial ND4 gene from intraspecific comparisons in four species of parasitic nematodes from the family Trichostrongylidae (38-50 sequences per species). The resulting pattern suggests a strong mutational bias toward A and T, and a lower transition/transversion ratio than is typically observed in other taxa. We also present information on the relative rates of substitution at first, second, and third codon positions and on relative rates of saturation of different types of substitutions in comparisons ranging from intraspecific to interordinal. Silent sites saturate extremely quickly, presumably owing to the substitution bias and, perhaps, to an accelerated mutation rate. Results emphasize the importance of using only the most closely related sequences in order to infer patterns of substitution accurately for nematodes or for other taxa having strongly composition-biased DNA. ND4 also shows high amino acid polymorphism at both the intra- and interspecific levels, and in higher level comparisons, there is evidence of saturation at variable amino acid sites. In general, we recommend using mtDNA coding genes only for phylogenetics of relatively closely related nematode species and, even then, using only nonsynonymous substitutions and the more conserved mitochondrial genes (e.g., cytochrome oxidases). On the other hand, the high substitution rate in genes such as ND4 should make them excellent for population genetics studies, identifying cryptic species, and resolving relationships among closely related congeners when other markers show insufficient variation.      

Campylocentrum guarinae sp. nov. (Vandeae,Orchidaceae) from Colombia

A new species of Campylocentrum from the Colombian Andes, C. guarinae, is described, illustrated and placed within a key to Colombian species of the genus. The new species resembles C. lansbergii from which it differs in vegetative and floral characters. The main differences between these species are described and illustrated.