Aonchotheca forresteri

Last updated

Aonchotheca forresteri
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Nematoda
Class: Enoplea
Order: Enoplida
Family: Capillariidae
Genus: Aonchotheca
Species:
A. forresteri
Binomial name
Aonchotheca forresteri
(Kinsella and Pence, 1987)
Synonyms
  • Capillaria forresteriKinsella and Pence, 1987 [1]
  • Aonchotheca forresteri: Pisanu and Bain, 2004 [2]

Aonchotheca forresteri is a parasitic nematode that infects the marsh rice rat (Oryzomys palustris) in Florida. Occurring mainly in adults, it inhabits the stomach. It is much more common during the wet season, perhaps because its unknown intermediate host is an earthworm that only emerges when it rains. The worm was discovered in 1970 and formally described in 1987. Originally classified in the genus Capillaria , it was reclassified in Aonchotheca in 1999. A. forresteri is small and narrow-bodied, with a length of 13.8 to 19.4 mm in females and 6.8 to 9.2 mm in males. Similar species such as A. putorii differ in features of the alae and spicule (organs in the male), the size of the female, and the texture of the eggs.

Contents

Taxonomy

Aonchotheca forresteri was discovered during a survey of the endoparasites of Florida marsh rice rats (Oryzomys palustris) by John Kinsella from 1970 to 1972, [3] and is one of several new parasite species in this study, which was done because there were no previous comprehensive studies of the endoparasites of the species. [4] Together with Danny Pence, Kinsella described the worm in a 1987 paper as Capillaria forresteri; the specific name honors Donald J. Forrester of the College of Veterinary Medicine, University of Florida. Kinsella and Pence described it as one of many species of Capillaria , a large and taxonomically difficult genus. They suggested that it may be closest to some other small species that live in the digestive systems of mammals, such as the very similar C. putorii , which is found in a variety of carnivorans in North America and Europe. [1] In 1982, Moravec had placed Capillaria putorii and a number of related species in a separate genus, Aonchotheca , and in 1999 Pisanu and Bain transferred Capillaria forresteri and various other species to that genus from Capillaria. Thus, the species is now known as Aonchotheca forresteri. [2]

Description

The marsh rice rat (here in Paynes Prairie, Florida, the type locality of A. forresteri), is the only known host of Aonchotheca forresteri. Oryzomys palustris Paynes.jpg
The marsh rice rat (here in Paynes Prairie, Florida, the type locality of A. forresteri), is the only known host of Aonchotheca forresteri.

Aonchotheca forresteri is a small, narrow-bodied worm. It is narrowest at the front and increases in width to about three fourths of its length. The cuticle, the surface layer, is smooth. Females are 13.8 to 19.4 mm long, averaging 16.9 mm, which makes them substantially longer than female A. putorii, and 55 to 70 (average 62) μm wide. The eggs are smooth, lacking the elaborate pattern on the surface seen in A. putorii, and are 53 to 58 (54) μm long and 21 to 24 (21) μm broad. The esophagus, the frontmost part of the digestive system, is 2.9 to 3.9 (3.6) mm long and is lined by 36 to 45 (40) cells known as stichocytes. The vulva is located 66 to 105 (83) μm behind the end of the esophagus and the anus is near the end of the worm, which is rounded. [1]

At 6.8 to 9.2 (7.7) mm, males are only about half as long as females. Their maximum width is 34 to 42 (37) μm. The length of the esophagus is 2.3 to 3.0 (2.6) mm, of which the muscular pharynx makes up 260 to 315 (273) μm, and is lined by 35 to 42 (37) stichocytes. The back region of the worm is 4.5 to 6.2 (5.1) mm long. The back, or rectal, opening of the digestive tube is located near the end of the worm, and the length of the cloaca is 530 to 576 (550) μm. Near the back end, there are two alae (ridges) at the sides (laterally), which are 40 to 55 (46) μm long; these are located at 10 to 15 μm from another, small ala at the tip. In A. putorii, the lateral alae are much longer and reach the ala at the tip. The spicule, a spikelike structure that functions in reproduction, is curved at the tip and hardened and has a length of 380 to 426 (406) μm. [1] It is smaller than that of the similar A. tamiasstriati from North American chipmunks and larger than that of A. murissylvatici from various North American and European small rodents, but about as long as that of A. putorii, which however lacks the curved tip. [5]

Distribution and ecology

Marsh rice rats from Paynes Prairie, Alachua County; Cedar Key, Levy County; and Lake Istokpoga, Highlands County, all in Florida, have yielded A. forresteri. In Paynes Prairie, the type locality, 82 of 178 animals examined were infected with 1 to 50 (average 10) worms, but in Cedar Key only a single rat contained one worm. The worms were found in the front part, or fundus, of the stomach, with their front ends in the fundal tissue and their back ends projecting into the inside. [1]

In Paynes Prairie, there was no significant difference in rate of infection between males and females, but only 4% of juveniles were infected, compared to 52% of adults. [1] Most species of Capillaria occur in multiple hosts, but A. forresteri has been found only in the marsh rice rat, even though several other small mammals (the round-tailed muskrat, Neofiber alleni; cotton mouse, Peromyscus gossypinus; hispid cotton rat, Sigmodon hispidus; and marsh rabbit, Sylvilagus palustris) occur in Paynes Prairie. The rice rat eats more animal food than any of those, and perhaps A. forresteri has an intermediate host that is not eaten by the other species. [6] A. forresteri is markedly more prevalent in the wet season (spring) than the dry season (autumn), perhaps because rainfall patterns influence the habits of the rice rat in some way. One possibility is that the intermediate host is an earthworm or other oligochaete worm that moves to the surface when it rains. [1]

Related Research Articles

Marsh rice rat Semiaquatic North American rodent in the family Cricetidae

The marsh rice rat is a semiaquatic North American rodent in the family Cricetidae. It usually occurs in wetland habitats, such as swamps and salt marshes. It is found mostly in the eastern and southern United States, from New Jersey and Kansas south to Florida and northeasternmost Tamaulipas, Mexico; its range previously extended further west and north, where it may have been a commensal in corn-cultivating communities. Weighing about 40 to 80 g, the marsh rice rat is a medium-sized rodent that resembles the common black and brown rat. The upperparts are generally gray-brown, but are reddish in many Florida populations. The feet show several specializations for life in the water. The skull is large and flattened, and is short at the front.

Eimeria kinsellai is an apicomplexan parasite of the genus Eimeria that infects the marsh rice rat. It was discovered in 1970 at Paynes Prairie, Alachua County, Florida. A different Eimeria, Eimeria palustris, has been found in Alabama marsh rice rats. E. kinsellai differs from other Eimeria found in rice rats, such as Eimeria couesii, Eimeria oryzomysi, Eimeria ojastii, and E. palustris, in anatomical details. It was named after parasitologist John M. Kinsella.

Skrjabinoclava kinsellai is a parasitic nematode worm that infects the marsh rice rat in Florida.

Lyperosomum intermedium is a parasitic trematode belonging to the subclass Digenea that infects the marsh rice rat. The species was first described in 1972 by Denton and Kinsella, who wrote that it was closest to Lyperosomum sinuosum, known from birds and raccoons in the United States and Brazil. Three years later, Denton and Kissinger placed the two, together with a number of other species, in a new subgenus of Lyperosomum, Sinuosoides. Species of Lyperosomum mainly infect birds; L. intermedium is one of the few species to infect a mammal.

Notocotylus fosteri is a parasitic fluke that infects the marsh rice rat in Florida.

Hassalstrongylus forresteri is a nematode worm of the genus Hassalstrongylus that infects the marsh rice rat in the United States. It was first described as Hassalstrongylus musculi by Marie-Claude Durette-Desset in 1972, but she later recognized it as a different species, H. forresteri. The females cannot be distinguished from those of the other species in the marsh rice rat, H. musculi and H. lichtenfelsi.

Hassalstrongylus musculi is a nematode worm of the genus Hassalstrongylus that infects the marsh rice rat and house mouse in the United States and Oryzomys couesi, Oligoryzomys fulvescens, and Handleyomys melanotis in San Luis Potosí, Mexico. It was first described as Longistriata musculi by Dikmans in 1935, but transferred to Hassalstrongylus in 1971 and 1972 by Marie-Claude Durette-Desset. She later renamed the material she had used to describe H. musculi in 1972 as H. forresteri. The females cannot be distinguished from those of the other species in the marsh rice rat, H. forresteri and H. lichtenfelsi.

Hassalstrongylus lichtenfelsi is a nematode worm of the genus Hassalstrongylus that infects the marsh rice rat in Florida. The females cannot be distinguished from those of the other species in the marsh rice rat, H. forresteri and H. musculi.

Cladotaenia circi is a tapeworm of the genus Cladotaenia that has birds of prey as its definitive host, such as the western marsh harrier, hen harrier, and peregrine falcon in Europe. It has been found at low frequencies in small mammals, such as the bank vole and common vole in Hungary and the marsh rice rat in Florida.

<i>Catatropis johnstoni</i> Species of fluke

Catatropis johnstoni is a fluke from the United States. It was first described in 1956 by Martin, who had found cercariae released by the snail Cerithidea californica in southwestern California. When the cercaria were fed into chickens, they developed into mature worms; Martin speculated that the natural host was a waterbird. In 1970, a study of helminths of the marsh rice rat in a saltmarsh at Cedar Key, Florida, found flukes similar to C. johnstoni. The fluke was present in 30% of 110 examined rice rats, with the number of worms per rat varying from 1 to 500. Some Cerithidea scalariformis snails from this marsh also released cercariae similar to C. johnstoni from California. When introduced into chickens, marsh rice rats, Mongolian gerbils, golden hamsters, and house mice, these cercariae developed into infectious flukes. Bush and Kinsella, who reported on the result in 1972, regarded the Florida and California flukes as the same species, as there were only minor size differences between them. Because no marsh-inhabiting rodent occurs in both California and Florida, they agreed with Martin that the normal host of C. johnstoni was most likely a bird, perhaps a rail or shorebird. Nevertheless, the rate of infection in the rice rat is too high for it to be just an accidental host; perhaps C. johnstoni is restricted to saltmarshes but not host-specific.

Fibricola lucida is a fluke that infects Virginia opossums, American minks, and marsh rice rats in North America. In a study in Florida, F. lucida was the only fluke of the marsh rice rat that occurred in both the freshwater marsh at Paynes Prairie and the saltwater marsh at Cedar Key. At the former locality, it infected 11% of rice rats and the number of worms per infected rat ranged from 1 to 65, averaging 17. At Cedar Key, 67% of rice rats were infected and the number of worms per infected rat ranged from 1 to 1975, averaging 143.

Capillaria gastrica is a parasitic nematode in the genus Capillaria. Among the known host species are the marsh rice rat and deermouse.

Litomosoides scotti is a parasitic nematode in the genus Litomosoides. First described in 1973, it infects the marsh rice rat and is known from a saltwater marsh at Cedar Key, Florida.

Parastrongylus schmidti is a species of parasitic nematode in the genus Parastrongylus. It was first described as Angiostrongylus schmidti in 1971 from the marsh rice rat in Florida, but later assigned to Parastrongylus.

Pterygodermatites ondatrae is a species of parasitic nematode in the genus Pterygodermatites. It has been recorded in the hispid cotton rat in Florida and Texas. In Florida, it has also been recorded on the marsh rice rat, together with an unnamed species of the same genus, the female of which cannot be distinguished from that of P. ondatrae.

Physaloptera hispida is a parasitic nematode in the genus Physaloptera. It has been found on the marsh rice rat, hispid cotton rat, Florida mouse, cotton mouse, and oldfield mouse in Florida.

Syphacia oryzomyos is a nematode that infects the marsh rice rat in Florida. A similar species of Syphacia has been recorded from the rice rats Oligoryzomys fulvescens and Handleyomys melanotis in San Luis Potosí, but because only females were found, this worm could not be identified to species.

Trichostrongylus affinis is a species of parasitic nematode in the genus Trichostrongylus. It primarily infects cottontails (Sylvilagus), but has also been found in the hispid cotton rat and the marsh rice rat.

Trichostrongylus sigmodontis is a species of parasitic nematode in the genus Trichostrongylus. It primarily infects the hispid cotton rat, but has also been found in the marsh rice rat.

References

  1. 1 2 3 4 5 6 7 Kinsella and Pence, 1987, p. 1295
  2. 1 2 Pisanu and Bain, 1999, p. 21
  3. ↑ Forrester, 1992, p. 100
  4. ↑ Kinsella, 1988, p. 275
  5. ↑ Kinsella and Pence, 1987, p. 1295; Pisanu and Bain, 1999, pp. 21, 23
  6. ↑ Kinsella and Pence, 1987, p. 1297

Literature cited

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.