page_title: Aonchotheca forresteri
section_title: Description
hierarchical_section_title: Aonchotheca forresteri / Description
caption_attribution_description: English: Marsh rice rat (Oryzomys palustris) in Paynes Prairie, Florida. This is presumably the subspecies O.&#160;p.&#160;natator, distinguished by more reddish fur.
context_page_description: Aonchotheca forresteri is a parasitic nematode that infects the marsh rice rat 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, the size of the female, and the texture of the eggs.
context_section_description: 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.
  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. 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.
caption: The marsh rice rat (here in Paynes Prairie, Florida, the type locality of A. forresteri), is the only known host of Aonchotheca forresteri.
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