Parasites, primates, and ant-plants: clues to the life cycle of Controrchis spp. in black howler monkeys (Alouatta pigra) in southern Belize

The purpose of this study was to investigate the prevalence, intensity, and possible transmission routes of the trematode, Controrchis spp. (Dicrocoeliidae), in a population of black howler monkeys (Alouatta pigra) near Monkey River, Belize. Alouatta pigra are arboreal primates that are typically folivorous and frugivorous. Controrchis is a dicrocoeliid trematode and, as such, should require a gastropod and an ant (Formicidae) intermediate host for transmission. From January to July 2005 and February 2006 to June 2007, we collected fecal samples and focal animal data from 18 individual primates in four social groups. Feces were stored in either 10% buffered formalin or 95% ethanol and examined using a double-centrifugation sugar-flotation technique. The prevalence of Controrchis spp. was 89%, and the mean intensity was 2.29 eggs per gram (epg), with a range of 1.00-6.57 epg. A general linear mixed model to examine the effect of sex, rainfall, and time spent feeding on various plant species, while controlling for individual and group identity, revealed that both group and the amount of time spent feeding on trumpet trees (Cecropia peltata) by individuals predicted the prevalence and intensity of Controrchis spp. infestation. Cecropia peltata has a mutualistic relationship with Azteca spp. ants and constitutes an important food source for A. pigra. Our findings provide strong, circumstantial evidence that A. pigra are infected with Controrchis spp. through the ingestion of metacercariae in Azteca spp. when feeding on C. peltata. Because C. peltata is a pioneer tree species and typically occurs in disturbed forests, results from this study suggest an important link between habitat disturbance and parasitism in a wild mammal.     

Parasites of free-ranging black howler monkeys (Alouatta pigra) from Belize and Mexico

Parasites are important members of the ecological web within which an animal lives, and can be used as indicators of ecosystem health. However, few baseline parasitological data are available for free-ranging animals, particularly for the black howler monkey (Alouatta pigra). In this study a total of 283 fecal samples were collected from 50 individually identified A. pigra during 2003 and 2004 and examined for parasites. The samples were processed using standard quantitative centrifugation concentration techniques, with sugar and zinc sulfate used as flotation media. The slides were examined using bright-field and phase microscopy. Antigen capture enzyme-linked immunosorbent assays (ELISAs) were used to detect protozoa. Four parasites were detected: 1) Controrchis biliophilus (Dicrocoeliidae), 2) Trypanoxyuris minutus (Oxyuridae), 3) Giardia sp. (Hexamitidae), and 4) Entamoeba sp. (Endamoebidae). Controrchis biliophilus was detected in 80% (wet season) and 81% (dry season) of the A. pigra samples; Trypanoxyuris minutus was detected in 8% (wet season) and 27% (dry season) of samples; and Giardia sp. was detected in 40% (wet season) and 27% (dry season) of samples. For the first time, DNA from Giardia sp.-positive fecal samples was extracted from A. pigra. Alouatta pigra individuals that lived near human settlements in Belize were infected with Giardia duodenalis (syn. G. lamblia, G. intestinalis) Assemblages A and B. These results suggest that G. duodenalis is transmitted from people and/or domestic animals to A. pigra.     

Intestinal Parasites of Free-ranging,Semicaptive,and Captive <Emphasis Type="Italic">Pongo abelii</Emphasis> in Sumatra,Indonesia

We collected fecal samples from 32 free-ranging, 19 semicaptive, and 54 captive Sumatran orangutans on Sumatra from 1998 until 2004 and screened them for gastrointestinal parasites. Our objectives were to compare the intestinal parasites of free-ranging, semicaptive, and captive orangutans and to evaluate the risk of parasite transmission in orangutan reintroduction programs. We identified 4 genera of Protozoa, 7 genera of nematodes, 1 trematode sp., and 1 cestode sp. The prevalence of Balantidium coli in free-ranging orangutans was significantly higher than in captive individuals. However, the prevalence of Strongyloides sp. was higher in captive than in free-ranging orangutans. Free-ranging female orangutans had a significantly higher total prevalence of intestinal parasites than that of males. We found no significant difference between parasite prevalences in different age groups. Compared to gorillas and chimpanzees, orangutans carry a smaller variety of protozoan and nematode species. Strongyloides sp. infections form the highest risk in reintroduction programs as crowding, ground-dwelling, and poor hygiene in captive and semicaptive orangutans may cause a constant reinfection.     

Blood parameters are little affected by time of sampling after the application of ketamine in black howler monkeys (Alouatta pigra)

Background Ketamine hydrochloride is an anesthetic commonly utilized to obtain biological samples in various non‐human primates. Its application alters individual hematologic and biochemical values. The aim of this study was to analyze its effect on blood parameters of Alouatta pigra. Method We collected blood samples at 10 and 40 minutes after the application of ketamine in 12 adult female A. pigra living in free‐ranging conditions. Results The analysis showed that 40 minutes after application of ketamine, the number of platelets, lymphocytes and concentration of phosphorus decreased; however, creatinine, cholesterol, triglycerides, and potassium values increased. Conclusions Our results suggest that ketamine appears to have little effect on the hematology and blood biochemistry of Alouatta pigra females with respect to those reported for other non‐human primates. It is also important to consider the elapsed time after their application when taking blood samples for proper interpretation of the hemogram of Alouatta pigra females.     

Recruitment of Black Howler Fruit Trees in Fragmented Forests of Northern Belize

We examined recruitment of trees whose seeds are dispersed by black howler monkeys (Alouatta pigra) in forest fragments within the Community Baboon Sanctuary in north-central Belize. In the fragments, most other large frugivores are absent and howlers dominate the large frugivore community. Consequently, we expected to observe an increased representation of howler fruit trees among the sapling community. To test this prediction preliminarily we observed howler feeding behavior for one year and conducted adult tree and sapling transects in 6 locations where howlers were present. We sampled a seventh site where howlers were absent for vegetation only. We found that in 4 of 6 sites there were proportionately fewer howler fruit saplings when compared to adult tree samples. However, when recruitment of howler fruit trees in the 6 sites was compared to a site where howlers were absent, 11 of 12 species had relatively higher recruitment. The lack of recruitment among howler fruit trees in general likely reflects differences in responses of individual species, as well as disruptions from human activities to natural processes within the forests. The observed lower recruitment patterns of howler trees suggest that over time, the abundance of the trees will likely decline and thus affect the foraging behavior and possibly survival of howlers in the fragmented forests.     

Effects of Ecology on the Gastrointestinal Parasites of Alouatta pigra

We examined the effects of demographic and ecological variables on the prevalence of intestinal parasites in free-ranging black howlers, Alouatta pigra, from Belize and Mexico. We collected 253 fecal samples from 50 individually identified monkeys during 2003. We processed all samples via standard centrifugation concentration techniques with sugar and zinc sulfate as flotation media. We used antigen capture enzyme-linked immunosorbent assays to detect protozoa. We analyzed data for each season separately. The most important factor in predicting whether an Alouatta pigra would be infected with a parasite was its membership in a particular social troop. It was not possible to isolate the effects of human presence, forest fragmentation, primate density, and the absence of Ateles geoffroyi on the prevalence of parasites in Alouatta pigra because the factors covaried. We detected few species of gastrointestinal parasites, possibly due to Alouatta pigra’s arboreal and herbivorous lifestyle and small geographic range. The prevalence of each parasite had a different pattern, with Controrchis sp. (presumed to be C. biliophilus), a fluke, tending to be more prevalent in Alouatta pigra that inhabited disturbed habitats, and Trypanoxyuris minutus, a pinworm, tending to be more prevalent in primates from undisturbed habitats. Giardia sp. tended to be more prevalent in primates at high densities. These results indicated that it is important to examine each parasite’s infection pattern separately to obtain a more accurate representation of the dynamics among the host, parasites, and ecology.     

Feeding ecology of the black howler monkey (Alouatta pigra) in Northern Belize

We studied the feeding ecology of the black howler monkey (Alouatta pigra) from March 1994 to April 1995 in the Community Baboon Sanctuary in northern Belize, Central America. Activity and diet composition were recorded using continuous focal animal sampling. Diet composition was compared with the relative abundance of plant parts eaten by the howlers within the study site. The study animals spent an average of 24.4% of their time feeding, 61.9% resting, and approximately 9.8% traveling. In contrast to previously published reports on A. pigra, we found the diet composition to be similar to that of other Alouatta species (conforming to the folivore/frugivore profile), with 41% of feeding time spent eating fruit, 45% foliage, and 11% flowers. This contrast may indicate a wide degree of dietary flexibility that allows A. pigra to inhabit a variety of habitat types. We suggest that a high level of resource abundance throughout the year makes the Community Baboon Sanctuary excellent habitat for Alouatta pigra. Am. J. Primatol. 45:263–279, 1998. © 1998 Wiley-Liss, Inc.     

Feeding Competition and Group Size in Alouatta pigra

Researchers consider group size in primates to be determined by complex relationships among numerous ecological forces. Antipredator benefits and better resource defense are the primary pressures for large groups. Conversely, intragroup limited food availability, can result in greater intragroup feeding competition and individual energy expenditure in larger groups, creating energetic advantages for individuals in small groups and placing an upper limit group size. However, the extent to which food availability constrains group size remains unclear for many species, including black howlers (Alouatta pigra), which ubiquitously live in small social groups (≤10 individuals). We studied the relationship between group size and 2 key indices of feeding competition—day journey length and activity budgets—in 3 groups of wild Alouatta pigra at a hurricane-damaged site in Belize, Central America. We controlled for differences in food availability between home ranges (food tree density) and compared both indicators of feeding competition directly with temporal variation in food availability for each group. Our results show no consistent association between resource availability, group size, and either index of competition, indicating that feeding competition does not limit group size at the site—i.e., that larger groups can form without increased costs of feeding competition. The results support the search for other explanations, possibly social ones, for small group size in the primates, and we conclude with suggestions and evidence for such alternative explanations.     

Molecular systematics and biogeography of the Neotropical monkey genus,Alouatta

We take advantage of the broad distribution of howler monkeys from Mexico to Argentina to provide a historical biogeographical analysis on a regional scale that encompasses the entire Neotropics. The phylogenetic relationships among 9 of the 10 recognized Alouatta species were inferred using three mitochondrial and two nuclear genes. The nuclear gene regions provided no phylogenetic resolution among howler monkey species, and were characterized by very low levels of sequence divergence between Alouatta and the Ateles outgroup. The mtDNA genes, on the other hand, produced a well-resolved phylogeny, which indicated that the earliest split among howler monkeys separated cis- and trans-Andean clades. Eight monophyletic mtDNA haplotype clades were identified, representing six named species in South America, including Alouatta seniculus, Alouatta sara, Alouatta macconelli, Alouatta caraya, Alouatta belzebul, and Alouatta guariba, and two in Mesoamerica, Alouatta pigra and Alouatta palliata. Molecular clock-based estimates of branching times indicated that contemporary howler monkey species originated in the late Miocene and Pliocene, not the Pleistocene. The causes of Alouatta diversification were more difficult to pin down, although we posit that the initial cis-, trans-Andean split in the genus was caused by the late Miocene completion of the northern Andes. Riverine barriers to dispersal and putative forest refuges can neither be discounted nor distinguished as causes of speciation in many cases, and one, the other or both have likely played a role in the diversification of South American howler monkeys. Finally, we estimated the separation of Mesoamerican A. pigra and A. palliata at 3Ma, which corresponds to the completion date of the Panama Isthmus promoting a role for this earth history event in the speciation of Central American howler monkeys.     

Survey of Helminth Parasites in Populations of <Emphasis Type="Italic">Alouatta palliata mexicana</Emphasis> and <Emphasis Type="Italic">A. pigra</Emphasis> in Continuous and in Fragmented Habitat in Southern Mexico

The 2 howler species that occur in southern Mexico, Alouatta palliata mexicana and Alouatta pigra are endangered, mainly as a result of habitat loss and fragmentation from human activity. Little is known about the gastrointestinal parasite communities affecting their populations, and lack of baseline information for populations of howler species in continuous forest habitats, makes evaluations of gastrointestinal parasite prevalence in populations in fragmented landscapes difficult. We report the results of a one-time broad survey of gastrointestinal parasites in fecal samples of individuals from several demographically stable populations of Alouatta palliata mexicana and A. pigra existing in continuous and/or protected forests. We further report similar data for populations of both species in human-fragmented landscapes. We detected 6 parasites for each howler monkey species, but only 3 of them (Trematode I, Controrchis biliophilus, Trypanoxyuris sp.) were common to both species. While parasitic prevalence in populations of both howler species was, in general, higher in the fragmented habitat than in continuous and/or protected forests. The difference is only marginally significant in Alouatta pigra. Some parasites (Coccidia and Strongylid) only appeared in populations in fragmented landscapes. Preliminary data suggest that adult males tended to have higher parasite prevalence values than those of adult females in both howler species. Parasite prevalence is associated to average group size, but not to population density in Alouatta pigra.     

The short-term effects of a hurricane on the diet and activity of black howlers (Alouatta pigra) in Monkey River, Belize

The diet and activity of a population of Alouatta pigra were compared before and immediately after a major hurricane to begin to explore how the monkeys cope with severe habitat destruction. Focal animal data were collected from January to April (dry season) for two seasons before (368 h) and one season after the storm (149 h) on a population of black howlers in Monkey River, Belize. During the first dry season after the storm, the monkeys changed their diet in direct accordance with the availability of food. The absence of fruit and flower production and the increase in new leaf availability forced the monkeys to adopt a completely folivorous diet. The activity budget of the monkeys also changed, and they spent more time inactive, which may be linked to the change in the distribution and type of food available. They also spent less time in social interactions, which may be due to the lower number of juveniles in the population or to the formation of new groups between unfamiliar individuals following the hurricane. The ability to live for long periods of time on leaves alone has allowed the remaining population to survive in the short term.     

Associations between shorebird abundance and parasites in the sand crab, Emerita analoga, along the California coast

I investigated spatial variation in the prevalence and abundance of 4 species of parasites in the sand crab, Emerita analoga, on 8 sandy beaches along 800 km of the California coast, to assess the importance of bird abundance for the distribution of parasites among sand crab populations. I collected sand crabs and counted shorebirds and gulls at each beach during June and November 1994. Sand crabs served as intermediate hosts for 4 species of parasites, including a trematode, Spelotrema nicolli (Cable and Hunnienen, 1938); an acanthocephalan, Polymorphus kenti (Van Cleave, 1947); a nematode, Proleptus sp., and an unidentified trypanorhynch tapeworm. Among sand crab populations, there was substantial spatial variation in the prevalence and abundance of each parasite species. No latitudinal pattern was apparent for any of the 4 species observed. Temporally, parasite prevalence and abundance was significantly different between dates for all 4 parasites. Specifically, sand crab populations experienced higher trematode, nematode, and trypanorhynch prevalence and abundance in November than in June. In contrast, prevalence and abundance of acanthocephalans were higher in June than in November. There were strong positive associations between bird abundance and prevalence of parasitic infection for trematodes and acanthocephalans for some dates but not for nematodes or trypanorhynchs, which use elasmobranchs as definitive hosts. The spatial variation in prevalence and abundance of trematodes and acanthocephalans observed among sand crab populations may be attributed to the distribution and abundance of shorebirds and gulls that serve as definitive hosts.     

Human infections of fish-borne trematodes in Vietnam: prevalence and molecular specific identification at an endemic commune in Nam Dinh province

The prevalence of fish-borne trematodes in humans and their molecular identification was investigated in the Rang Dong commune of Nam Dinh province, Vietnam, between January 2009 and December 2010. A total of 405 people in this commune were interviewed on the habit of eating raw fish and all of their stool samples were collected using the Kato-Katz technique for examination of the presence of fish-borne trematodes. The worms (and eggs) were first morphologically examined, counted, described and identified, then the representative isolates were subjected for molecular species confirmation. A total of 385 adult flukes collected from 10 patients were morphologically identified to species and defined as Clonorchis sinensis (14.58%) in Opisthorchiidae family, Haplorchis taichui (32.29%), Haplorchis pumilio (52.08%) and Centrocestus formosanus (1.04%) in Heterophyidae family. A high rate (77.8%) of the interviewees was found to have the habit of eating raw fish. This habit was attributed to the high infection rate of fish-borne trematode in humans (22.72%; OR = 2.486). The infection rate of fish-borne trematodes in males was higher (29.3%) than that in females (16.0%) and increased by age, reaching the highest in the patients aged 40–59 years (28.2–28.7%). The infection intensity of fish-borne trematode was found light (336 EPG). Adult flukes were collected from a group of the patients with the highest intensity of infection and subjected to molecular and phylogenetic analysis using a portion (326 bp) of mitochondrial cox1. Phylogenetic tree inferred from cox1 sequences using sequence data for 34 isolates of opisthorchid, heterophyid, fasciolid, paragonimid, schistosomid trematodes and taeniid cestodes revealed that they are distinct groups. The newly collected with the known clonorchid and heterophyid isolates form the well defined taxonomic groups, respectively, confirming that C. sinensis and Haplorchis spp. (H. pumilio and H. taichui) were among the collected samples.     

Impact of intrasexual selection on sexual dimorphism and testes size in the Mexican howler monkeys Alouatta palliata and A. pigra

One of the goals of physical anthropology and primatology is to understand how primate social systems influence the evolution of sexually selected traits. Howler monkeys provide a good model for studying sexual selection due to differences in social systems between related species. Here, we examine data from the sister howler monkey species Alouatta palliata and A. pigra inhabiting southeastern Mexico and northern Guatemala. We use a resampling approach to analyze differences in sexual dimorphism of body and canine size. In addition, we compare testes size as a way of gauging the intensity of sperm competition in both species. Morphometric data were collected from wild-caught individuals, including body mass and length, and dental data were obtained from casts from wild individuals and from museum specimens. Although A. pigra individuals are larger than their A. palliata counterparts, we find that both species exhibit similar levels of sexual dimorphism for all of the variables considered. Testicular volume results indicate that A. palliata male testes are on average twice as large as those of A. pigra males, suggesting more intense sperm competition in the former species. Our study shows that A. pigra is not highly sexually dimorphic as was once thought, and testes size differences suggest the need for a clearer understanding of howler monkey social systems.     

Demographic survey of black howler monkey (Alouatta pigra) in the Lachuá Eco-region in Alta Verapaz, Guatemala

Guatemala harbors three species of primates (Alouatta palliata, Alouatta pigra and Ateles geoffroyi), but the distribution and state of conservation of populations of these species are poorly documented. In the case of A. pigra, populations have been studied recently and documented in several sites in Mexico and Belize, and only in one site in Guatemala (Tikal National Park). In this study, we report first-time population data for A. pigra existing in the Lachuá Eco-region in northwestern Guatemala. Surveys were conducted between September 2002 and April 2003 in the northern portion (32 km2) of the Lachuá National Park (LLNP; 145 km2) and in a fragmented landscape north of the protected area. In this latter area we surveyed a large forest fragment (17.14 km2), "Nueve Cerros", and 26 small forest fragments that ranged in size from 0.01 to 3.9 km2. Surveys resulted in a total count of 414 howler monkeys of which 403 belonged to 80 mixed-sex groups, four were solitary males, two were solitary females and five were found in two male groups. Standardized sampling effort among sites indicated 16.7 monkeys/100 survey hours at LLNP, 35.8 individuals/100 survey hours at "Nueve Cerros" and 71.0+/-62.2 individuals/100 survey hours in the forest fragments. Mean group size varied from 4.07 individuals at LLNP to 5.19 individuals in the forest fragments. Conservation problems for the black howler population surveyed are discussed, along with possible conservation scenarios.     

Current status of the habitat and population of the black howler monkey (Alouatta pigra) in Balancán, Tabasco, Mexico

We evaluated the habitat and populations of the black howler monkey (Alouatta pigra) in the municipality of Balancán, Tabasco, southeastern Mexico, using a combination of field surveys and remotely sensed data. We identified 21,937 ha of remnant vegetation composed of 1,348 fragments. Fragments separated by up to 200 m were grouped into "clusters" of fragments in accordance with the maximum observed open distance crossed by A. pigra. A total of 11% or 84 of the 772 clusters identified through remote sensing were selected at random, and for these we determined the vegetation type, canopy height, area, and distance to the closest human settlement. In these same 84 clusters, which included a total area of 9,817 ha, from October to June of 2006 we located a total of 1,064 black howler monkeys, including 228 troops and 49 solitary monkeys. A. pigra was found in 62 (74.7%) of all clusters visited, with a cumulative area of 6,032 ha. Troops varied in size from 2 to 15 individuals (average 6.0+/-2.9 ind/troop). Adults were 67% (n=716) of detected individuals, whereas juveniles were 20.5% (n=218) and infants were 12.5% (n=133). We found black howlers to occur at an ecological density of 10.8 ind/km(2), which is low in comparison with A. pigra in other fragmented and conserved sites. We found a statistically significant relationship between the area of clusters and the abundance of howler monkeys (r(2)=0.2, F=10.47, gl=3, P=0.002). In addition, the probability of finding A. pigra was greater in secondary vegetation, riparian vegetation, tropical dry forest, undisturbed tropical oak forest, and palm forest (F=12, gl=3, P<0.0001), as compared with disturbed tropical oak forest. Our results provide data on the distribution, abundance, and population structure of black howler monkeys in a fragmented landscape in the southeast of Mexico. These data are a necessary prerequisite for conservation planning for this species.     

Helminth and intestinal protozoa infections, multiparasitism and risk factors in Champasack province, Lao People's Democratic Republic

Background

Detailed investigations of multiparasitism are scarce in the Mekong River basin. We assessed helminth (trematode, nematode, and cestode), and intestinal protozoa infections, and multiparasitism in random population samples from three different eco-epidemiological settings in Champasack province, southern Lao People''s Democratic Republic (Lao PDR), and determined underlying risk factors.

Methodology

Two stool samples were collected from 669 individuals aged ≥6 months over consecutive days and examined for helminth infections using the Kato-Katz method. Additionally, one stool sample per person was subjected to a formalin-ethyl acetate concentration technique for diagnosis of helminth and intestinal protozoa infections. Questionnaires were administered to obtain individual and household-level data pertaining to behavior, demography and socioeconomic status. Risk factors for hepato-biliary and intestinal parasitic infections and multiparasitism were determined using multiple logistic regressions analyses.

Principal Findings

Multiple species intestinal parasite infections were common: 86.6% of the study participants harbored at least two and up to seven different parasites concurrently. Regarding nematode infections, hookworm was the most prevalent species (76.8%), followed by Ascaris lumbricoides (31.7%) and Trichuris trichiura (25.0%). Regarding trematodes, Opisthorchis viverrini and Schistosoma mekongi infections were found in 64.3% and 24.2% of the participants, respectively. Infections with intestinal protozoa were rare.

Conclusions/Significance

There is a pressing need to intensify and sustain helminth control interventions in the southern part of Lao PDR. Given the high prevalence with nematode and trematode infections and the extent of multiparasitism, preventive chemotherapy is warranted. This intervention should be coupled with health education and improved access to clean water and adequate sanitation to consolidate morbidity control and enhance sustainability.     

Negative influence of Gammarinema gammari (Nematoda) on the fecundity of Microphallus papillorobustus (Trematoda): field and experimental evidence

The gammarid amphipod Gammarus insensibilis frequently harbors adult individuals of the ectoparasitic nematode Gammarinema gammari as well as metacercariae of the trematode Microphallus papillorobostus. After the demonstration in a previous study of a negative relationship between the abundance of these 2 parasites, the nature of the relationship between these 2 parasites was explored in more detail by studying, in the field and in the laboratory, the influence of nematode abundance on trematode fecundity. In gammarids collected in the field, a negative relationship between metacercarial fecundity and the number of co-occurring nematodes was found. By manipulating the nematode abundance in the laboratory, it was confirmed that G. gammari has a negative effect on egg production in M. papillorobustus.     

Helminth parasites of the tropical gar, Atractosteus tropicus Gill, from Tabasco, Mexico

A total of 8 helminth species were recorded in an examination of 43 tropical gar, Atractosteus tropicus Gill, collected at the Pantanos de Centla Biosphere Reserve, Tabasco, Mexico. The parasite species included 1 adult trematode, 3 metacercariae, 1 cestode, 1 adult nematode, and 2 nematode larvae. Six of these 8 species were rare, with low prevalence (< 17%) and abundance (< 1.0 helminths per examined fish). The larvae of Contracaecum sp. were the most abundant in the sample, constituting 60% of the total helminths (64% prevalence, 3.8 +/- 5.2 abundance), followed by the cestode Proteocephalus singularis, constituting 18% of the worms (30.5% prevalence, 1.1 +/- 3.0 abundance). Species richness, individual parasite abundance, and diversity were low in the infracommunities. The recording of 3 specialist species in the tropical gar confirms that the helminth fauna of gar has an appreciable degree of specificity. This study indicates the importance of ecological determinants of richness in helminth communities of the tropical gar.     

Short communication. First record of Torticaecum sp. (Trematoda: Didymozoidae) in the chaetognath Serratosagitta serratodentata (Krohn, 1853) from Caribbean waters

From samples collected in the Caribbean Sea during February, March, May and August 1991, a total of 22 508 holoplanktonic chaetognaths were caught. During the analyses of the samples, one non-cysted specimen of didymozoid metacercaria was found in the coelom of the chaetognath Serratosagitta serratodentata (prevalence 0.004%). Owing to the lack of an authentic stomach and the morphology of the intestine, this trematode seems to belong to the Torticaecum larval type. This is the first report of both the chaetognath species as a host and the geographical locality for this parasite.