Temporal occurrence and community structure of helminth parasites in southern leopard frogs, Rana sphenocephala, from north central Oklahoma.

Currently, little information is available about the temporal recruitment of helminth communities in amphibian hosts. We examined the helminth community structure and temporal recruitment of helminth parasites in southern leopard frogs, Rana sphenocephala. Specifically, we were interested in how host life history such as habitat, age and/or size, diet, sex, and temporal variation in abiotic factors (precipitation and temperature) were important in determining monthly infection patterns of helminth populations and communities in southern leopard frogs. From May to September 2011, 74 southern leopard frogs were collected from Teal Ridge in Stillwater Payne County, OK, USA. Sixty-nine (93 %) of 74 frogs were infected with 1 or more helminth species. During our collecting period, the average monthly temperature was lowest in May and highest in July, and monthly precipitation was highest in May and lowest during the first week of September. The component community consisted of 11 species of helminth, including 1 larval and 1 adult cestode, 2 larval and 3 adult trematodes, and 1 juvenile and 3 adult nematodes. Of the 1790 helminths recovered, 51 % (911) were nematodes, 47 % (842) were cestodes, and 2 % (37) were trematodes. There were significant differences in the total abundance and mean species richness of helminths acquired by skin contact or through frog diet in monthly component communities of southern leopard frogs. A positive correlation existed for percentage of all helminths acquired by skin contact and monthly precipitation (r = 0.94, P < 0.01). Conversely, a negative correlation existed for monthly precipitation and percentage of helminths acquired by diet (r = -0.94, P < 0.01). Our results indicate that abiotic conditions such as precipitation have a major influence on the avenues for and constraints on the transmission of helminths with life cycles associated with water/moisture or terrestrial intermediate/paratenic hosts and are important in structuring helminth communities of amphibian hosts.

Co-occurrence of Haematoloechus complexus and Rhabdias joaquinensis in the plains leopard frog from Nebraska.

Species of Haematoloechus and Rhabdias both are ubiquitous lung parasites of frogs, yet surprisingly little research has been conducted on the interactions between these worms. In a small Nebraska stream, 256 Rhabdias joaquinensis and 225 Haematoloechus complexus were found in the lungs of Lithobates (=Rana) blairi. Thirty-six of the 44 (82%) frogs were co-infected with H. complexus and R. joaquinensis whereas 5 (11%) frogs were infected with only 1 species and 3 (7%) frogs were uninfected. Tests for association between H. complexus and R. joaquinensis found a significant positive relationship between the 2 parasites. Significant positive relationships in intensity of infection were found when both lungs were combined but not when lungs were considered individually. Tests for association between H. complexus and R. joaquinensis found no relationship between the worms in the anterior and posterior portions of the lungs. These data suggest that H. complexus and R. joaquinensis do not competitively exclude each other from the lungs of L. blairi in southeastern Nebraska.

New host and distribution records for Aplectana hamatospicula (Ascaridida: Cosmocercidae) in Gastrophryne olivacea (Anura: Microhylidae) from the Great Plains U.S.A.

Aplectana hamatospicula is a nematode that parasitizes the large intestine of anurans, and has been reported from bufonids, eleutherodactylids, hylids, microhylids, and ranids from North and Central America. Aplectana hamatospicula was first described, over 70 yr ago, from Hyla eximia and Bufo peltocephalus from Mexico and Cuba, respectively, and reported from Gastrophryne carolinensis from Florida. Since then there have been no reports of this nematode in North America north of Mexico. The life cycle of A. hamatospicula is not known, and there is limited information on Aplectana spp. from North America. During 2010-2011, we collected 351 anurans of 8 species from 4 locations in Stillwater, Payne County, Oklahoma, U.S.A., and examined them for the presence of Aplectana spp. Of the 8 species of anurans surveyed, A. hamatospicula infected only the Great Plains narrowmouth toad (Gastrophryne olivacea). The prevalence of A. hamatospicula was 85.7% (12/14) with a mean abundance of 28.4 + 24.0 and a mean intensity of 33.1 + 22.8 worms per infected toad. We provide new morphological measurements for male and female A. hamatospicula along with new locality records for this nematode in North America.