Molecular evidence linking the larval and adult stages of Mexiconema cichlasomae (Dracunculoidea: Daniconematidae) from Mexico, with notes on its phylogenetic position among Dracunculoidea

2018 ◽  
Vol 93 (05) ◽  
pp. 580-588 ◽  
Author(s):  
A.L. May-Tec ◽  
A. Martínez-Aquino ◽  
M.L. Aguirre-Macedo ◽  
V.M. Vidal-Martínez

AbstractWe describe the larval developmental stages and life cycle of the dracunculid nematodeMexiconema cichlasomaein both the intermediate,Argulus yucatanus(Crustacea: Branchiura), and definitive hosts,Cichlasoma urophthalmus(Perciformes: Cichlidae), from the Celestun tropical coastal lagoon, Yucatan, Mexico. The morphological analyses showed significant differences between the total length of L1 found inM. cichlasomaegravid female and L2–L3 inA. yucatanus.This result indicates that theM. cichlasomaelarval development occurs in the intermediate host. We obtained sequences from the small subunit (SSU) ribosomal marker from larval stages ofM. cichlasomaeinA. yucatanusand adult nematodes inC. urophthalmus. Our morphological and molecular results support conspecificity betweenM. cichlasomaelarvae inA. yucatanusand the adult stages inC. urophthalmus. We briefly discuss the phylogenetic position ofM. cichlasomaeamong the Daniconematidae, and provide evidence of the monophyly of the daniconematids associated with branchiurid intermediate hosts. Based on the phylogenetic results, we support the transfer of theMexiconemagenus to the family Skrjabillanidae and do not support the lowering of family Daniconematidae to subfamily.

1995 ◽  
Vol 69 (1) ◽  
pp. 69-75 ◽  
Author(s):  
T. Scholz ◽  
M.C.F. Pech-Ek ◽  
R. Rodriguez-Canul

AbstractField study on the biology of Crassicutis cichlasomae Manter, 1936 (Digenea: Homalometridae) was carried out in a small swamp in a limestone factory near Mérida, Yucatán, Mexico. Aquatic snails, Littorina (Littoridinopsis) angulifera, harbouring C. cichlasomae rediae, cercariae and metacercariae, served both as the first and second intermediate hosts. Feeding experiments confirmed the conspecificity of metacercariae from naturally infected snails with adults from naturally infected fish. Gravid C. cichlasomae worms were obtained from experimentally infected fish 19 days post exposure at 22–24°C. Examination of fish from the swamp in Mitza and other localities in the Yucatan Peninsula showed that the cichlids Cichlasoma urophthalmus and C. meeki were definitive hosts of C. cichlasomae. There was no pronounced preference of C. cichlasomae adults for the site of their location in the intestine of the definitive host; a slightly higher proportion (41%) of worms was only found in the anterior third of the gut. The time of miracidium development varied from 18.5 to 27.5 days; different temperature (20.1–35.7°C) or light/darkness regimes influenced only slightly the rate of embryonic development, with shorter development times at higher temperature (34.8–35.7°C) and constant darkness and/or light. With the exception of the sporocyst, all developmental stages are described and figured.


1987 ◽  
Vol 65 (10) ◽  
pp. 2491-2497 ◽  
Author(s):  
Murray J. Kennedy ◽  
L. M. Killick ◽  
M. Beverley-Burton

Life cycle studies of Paradistomum geckonum (Dicrocoeliidae) were attempted experimentally. The pulmonate gastropod Lamellaxis gracilis served as the first intermediate host; geckonid lizards (Cosymbotus platyurus, Gehyra mutilata, and Hemidactylus frenatus) served as definitive hosts. The life cycle of Mesocoelium sociale (Mesocoeliidae) was studied in naturally infected first intermediate hosts (L. gracilis, Huttonella bicolor) and experimentally in geckonid definitive hosts (C. platyurus, G. mutilata, and H. frenatus). Some naturally infected L. gracilis were infected concurrently with larval stages of both digeneans. Second intermediate hosts, presumed to be arthropods, were experimentally unnecessary. Metacercariae of P. geckonum were not found. Cercariae of M. sociale formed encysted metacercariae in the same individual snails.


2021 ◽  
Vol 106 ◽  
pp. 325-339
Author(s):  
Shirley A. Graham ◽  
Peter W. Inglis ◽  
Taciana B. Cavalcanti

Crenea Aubl. (Lythraceae) is a ditypic genus of subshrubs occurring in mangrove vegetation on the coasts of northern South America. Phylogenetic analyses based on morphology have offered unresolved and conflicting phylogenetic positions for the genus in the family. This study presents the first molecular sequences for Crenea, from nrITS, rbcL, trnL, trnL-F, and matK regions. Molecular phylogenetic analyses find full support for Crenea within Ammannia L., a relationship not previously recognized. Ammannia is a globally distributed genus of terrestrial to amphibious herbs mostly occurring in freshwater marshes and wetlands. It was recently reconfigured based on phylogenetic evidence to include the genera Nesaea Comm. ex Kunth and Hionanthera A. Fern. & Diniz. The transfer of Crenea to Ammannia further extends the morphological, ecological, and biogeographical diversity of Ammannia and provides the final evidence defining Ammannia as a monophyletic lineage of the Lythraceae. A revised circumscription of Ammannia s.l. adds several new morphological character states and the first species in the genus restricted to mangrove vegetation. Two changes in taxonomic status are made: Ammannia maritima (Aubl.) S. A. Graham, P. W. Inglis, & T. B. Cavalc., comb. nov., and Ammannia patentinervius (Koehne) S. A. Graham, P. W. Inglis, & T. B. Cavalc., comb. nov. The new combinations are described, a list of exsiccatae examined is provided, and the effects of the reconfiguration to the morphology and biogeography of the genus are detailed.


<em>ABSTRACT. Myxobolus cerebralis </em>possesses unique phenotypic and genotypic characteristics when compared with other histozoic parasites from the phylum Myxozoa. The parasite infects the cartilage and thereby induces a serious and potentially lethal disease in salmonid fish. Comparisons of the small subunit ribosomal DNA (ssu rDNA) sequences of <em>M. cerebralis </em>to other myxozoans demonstrate that the parasite has evolved separately from other <em>Myxobolus </em>spp. that may appear in cartilage or nervous tissues of the fish host. <em>Myxobolus cerebralis </em>has a complex life cycle involving two hosts and numerous developmental stages that may divide by mitosis, endogeny, or plasmotomy, and, at one stage, by meiosis. In the salmonid host, the parasite undergoes extensive migration from initial sites of attachment to the epidermis, through the nervous system, to reach cartilage, the site where sporogenesis occurs. During this migration, parasite numbers may increase by replication. Sporogenesis is initiated by autogamy, a process typical of pansporoblastic myxosporean development that involves the union of the one cell (pericyte) with another (sporogonic). Following this union, the sporogonic cell will give rise to all subsequent cells that differentiate into the lenticular shaped spore with a diameter of approximately 10 µm. This spore or myxospore is an environmentally resistant stage characterized by two hardened valves surrounding two polar capsules with coiled filaments and a binucleate sporoplasm cell. In the fish, these spores are found only in cartilage where they reside until released from fish that die or are consumed by other fish or fish-eating animals (e.g., birds). Spores reaching the aquatic sediments can be ingested and hatch in susceptible oligochaete hosts. The released sporoplasm invades and then resides between cells of the intestinal mucosa. In contrast to the parasite in the fish host, the parasite in the oligochaete undergoes the entire developmental cycle in this location. This developmental cycle involves merogony, gametogamy or the formation of haploid gametes, and sporogony. The actinosporean spores, formed at the culmination of this development, are released into the lumen of the intestine, prior to discharging into the aquatic environment. The mechanisms underlying the complex development of <em>M. cerebralis</em>, and its interactions with both hosts, are poorly understood. Recent advances, however, are providing insights into the factors that mediate certain phases of the infection. In this review, we consider known and recently obtained information on the taxonomy, development, and life cycle of the parasite.


Parasitology ◽  
1964 ◽  
Vol 54 (1) ◽  
pp. 1-41 ◽  
Author(s):  
B. L. James

1. Parvatrema homoeotecnum sp.nov. from the oystercatcher, Haematopus ostralegus occidentalis Neumann at Aberystwyth is described and compared with other species of the genus.2. The life cycle of this species is unique. The larval stages occur in the gastropod, Littorina saxatilis (Olivi) subsp. tenebrosa (Montagu) and include germinal sacs which have a structure and development similar to an adult digenean. There are no free-living stages and only one intermediate host.3. The significance of this unique life cycle is discussed.4. The family Gymnophallidae Morozov, 1955, is reviewed. Emended definitions are given for the family, subfamilies and genera. Keys, diagnostic features and brief notes of the species are included.I am very grateful to Dr Gwendolen Rees, who suggested the investigation which led to the discovery of this species, for her advice and indispensable assistance throughout the work and the preparation of this paper. I am also grateful to the late Professor T. A. Stephenson for his interest and for the provision of working facilities; to Mr W. A. Ballantine, Mr A. H. Clarke, Jr., Mr C. Curtis, Miss G. P. F. Evans, Dr V. Fretter, Professor L. A. Harvey, Mr D. H. Jones and Dr J. Lewis who sent me specimens of Littorina saxatilis; to Professor R. M. Cable and Emerit. Professor G. R. La Rue for helpful suggestions; to Mr J. R. Hirst and Mr D. Hemingway Jones for photographic and technical assistance and to the Department of Scientific and Industrial Research for a grant which made the work possible.


Parasitology ◽  
2017 ◽  
Vol 144 (14) ◽  
pp. 1922-1930 ◽  
Author(s):  
V. COLELLA ◽  
M. A. CAVALERA ◽  
G. DEAK ◽  
V. D. TARALLO ◽  
C. M. GHERMAN ◽  
...  

SUMMARYNematodes of the Angiostrongylidae family, such as Angiostrongylus vasorum and Angiostrongylus cantonensis, may cause potentially life-threatening diseases in several mammal species. Alongside these well-known species, Angiostrongylus chabaudi has been recently found affecting the cardiopulmonary system of domestic and wild cats from Italy, Germany, Greece, Romania and Bulgaria. Nonetheless, significant gaps in the understanding of A. chabaudi epidemiology include the lack of information of species acting as intermediate host and of the morphological description of larval stages. Cornu aspersum (n = 30) land snails were infected with 100 first-stage larvae of A. chabaudi collected from a naturally infected wildcat in Romania. Larvae at different developmental stages were found in 29 out of 30 (96·7%) infected snails and a total of 282 (mean 9·8 ± 3·02 larvae per each specimen) were collected from the gastropods. Here we demonstrate that A. chabaudi develops in snails and report C. aspersum as potential intermediate host for this parasitic nematode. Findings of this study are central to understand the ecological features of feline angiostrongylosis and its epidemiology within paratenic and intermediate hosts.


Microbiology ◽  
2005 ◽  
Vol 151 (1) ◽  
pp. 301-309 ◽  
Author(s):  
Astrid Collingro ◽  
Sven Poppert ◽  
Eva Heinz ◽  
Stephan Schmitz-Esser ◽  
Andreas Essig ◽  
...  

Chlamydiae are a unique group of obligate intracellular bacteria comprising important pathogens of vertebrates as well as symbionts of free-living amoebae. Although there is ample molecular evidence for a huge diversity and wide distribution of chlamydiae in nature, environmental chlamydiae are currently represented by only few isolates. This paper reports the recovery of a novel environmental chlamydia strain from activated sludge by co-cultivation with Acanthamoeba sp. The recovered environmental chlamydia strain UV-7 showed the characteristic morphology of chlamydial developmental stages as revealed by electron microscopy and was identified as a new member of the family Parachlamydiaceae (98·7 % 16S rRNA sequence similarity to Parachlamydia acanthamoebae). Infection studies suggested that Parachlamydia sp. UV-7 is not confined to amoeba hosts but is also able to invade mammalian cells. These findings outline a new straightforward approach to retrieving environmental chlamydiae from nature without prior, tedious isolation and cultivation of their natural host cells, and lend further support to suggested implications of environmental chlamydiae for public health.


Phytotaxa ◽  
2020 ◽  
Vol 443 (3) ◽  
pp. 211-257
Author(s):  
RENATA CARMO-OLIVEIRA ◽  
LUCIANA NASCIMENTO CUSTÓDIO ◽  
BERTA LANGE DE MORRETES ◽  
PAULO EUGÊNIO OLIVEIRA

Embryological data provides insights into the taxonomy and evolution of angiosperms.  Vochysiaceae is a mostly Neotropical family whose phylogenetic position was greatly influenced by reconstructions based on molecular data, and despite its monosymmetric and oligostemonous flowers, was included as a sister group of polysymmetric and polystemonous Myrtaceae. However, molecular data has yet to resolve the relationships between the genera inside the family. We analysed the early embryology of some species of five out of the six generally accepted Neotropical genera using sequential histological analyses to compare the microsporogenesis and gametogenesis and megasporogenesis and gametogenesis between clades and with the embryology of the well-studied Myrtales. We observed some marked differences in timing and developmental stages, which somewhat corroborate the clades defined from molecular data. Multiple archesporium and embryo sacs, as well as megagametophyte maturation and fertilization long after anthesis, characterized the Qualea-Ruizteranea-Callisthene (QRC) clade, while single embryo sac mature at anthesis characterized the Vochysia-Salvertia (VS) clade. Tri-cellular pollen only occurred in Salvertia convallariodora. Seven of the eight main embryological features supported the Myrtales as present in Vochysiaceae and the remaining one, inner integument with two layers of cells, was observed in some Qualea. Thus, the studied Vochysiaceae embryology conforms very well within the order and only their strongly monosymmetric and oligostemonous flowers are less common among Myrtales.


2018 ◽  
Vol 63 (2) ◽  
pp. 354-359 ◽  
Author(s):  
Felipe de Sousa Lourenço ◽  
Germán Augusto Murrieta Morey ◽  
José Celso de Oliveira Malta

AbstractThe family Neoechinorhynchidae includes seven species ofNeoechinorhynchusfrom freshwater fishes of Brazil. Although severalNeoechinorhynchusspecies are cited infecting different fish species in Brazil, there is a lack of information concerning to their life cycle and the identification of the intermediate hosts. Thus, the aim of the present study was to describe the development ofNeoechinorhynchus buttneraein its intermediate host collected in a fish farm located in Rio Preto da Eva, Amazonas, Brazil. To verify the presence ofN. buttneraein the fish pond, twentyColossoma macropomumwere captured and analyzed, being corroborated the presence of this parasite species. Samples of plankton were also collected, finding the ostracodCypridopsis viduaas the intermediate host. For the description of the larvae development, a laboratory experimental procedure was conducted by feeding the collected ostracods with the eggs of the adult specimens taken from the sampled fish. To observe the stages of development an artificial hatch was performed. Every stage of development was photographed, measured, drawn and described. The time of development of the immature stages ofN. buttneraewas 29 days, reporting the stages: acanthor, acanthella (with eight developmental changes) and cystacanth. As high infections byN. buttneraecauses morphological damages to the intestine and may compromise the quality ofC. macropomumand in consequence the production of fish farmers in the Brazilian Amazon region, the knowledge of its intermediate host and the understanding of its life cycle represents a useful information to prevent and combat infections by this parasite.


1988 ◽  
Vol 36 (2) ◽  
pp. 111 ◽  
Author(s):  
TH Cribb

A population of Prototransversotrema steeri Angel, 1969 is recorded from the introduced fish Gambusia affinis and the native species Pseudomugil signifer and Mugil cephalus in fresh water in Queensland, Australia. Adults of P. steeri are considerably smaller than adults previously described from marine fish. This appears to be a host-related phenomenon, possibly reflecting the size of the subscale niche offered by the host. The intermediate host is Posticobia brazieri, a hydrobiid snail. It is suggested that different hydrobiid snails may act as intermediate hosts in other parts of Australia. The miracidium develops into a mother sporocyst which produces a single mother redia. Mother rediae produce daughter rediae which may produce further daughter rediae or cercariae. Cercariae emerge from the redia while still embryonic and develop independently in the tissues of the snail. Upon emergence the cercariae attach directly to the definitive host and commence egg-production within 6 days. Gambusia affinis, Xiphophorus rnaculatus, X. helleri, Craterocephalus marjoriae and Mugil cephalus were all infected experimentally. I discuss various theories concerning the phylogenetic position of the Transverso- trematidae within the Digenea and conclude that the family occupies an isolated position not closely allied with any other group.


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