Known hosts of the nematode endoparasite ( Ascarididae : Hexametra angusticaecoides ) , including the Madagascar leaf-nosed snake ( Lamprophiidae : Langaha madagascariensis )

The nematode endoparasite, Hexametra angusticaecoides Chabaud and Brygoo, is an intestinal and coelomic nematode known only from lizards and snakes. Herein, we provide a list of all known hosts to date, and document a new host, the Madagascar leaf-nosed snake, Langaha madagascariensis Bonnaterre (Lamprophiidae). Because the known paratenic hosts (mosquitos, midges, and cockroaches) of Hexametra angusticaecoides are all extremely common in Florida, as well as Florida having the highest number of established non-native amphibians and reptiles in the entire world, this should be a concern to biologists and conservationists regarding imported animals for the pet trade.


Introduction
The nematode endoparasite, Hexametra angusticaecoides Chabaud and Brygoo, 1960, is an intestinal and coelomic nematode of lizards and snakes.Hexametra angusticaecoides larvae are ingested by larval stages of mosquitos (Culex), midges (Chrironomus), and cockroaches (Periplaneta orientalis) (Anderson 2000;Baker 1989), where they enter the malpighian tubules and lie dormant without growth (Anderson 2000).It is via consumption of these insects that H. angusticaecoides is then passed into the intermediate/primary host (i.e., chameleon) (Coke 1997).Second stage H. angusticaecoides larvae pass into the body cavity of the host where they begin to grow, but have also been found in stomach, liver, abdominal fat bodies, subcutaneous space, lungs (Coke 1997), and intestines (Anderson 2000).Anderson (2000) hypothesized that the adult stage of H. angusticaecoides may re-enter the intestinal system via the lungs.Within the subcutaneous and alimentary tract of the intermediate/primary host, the nematode persists as an adult (Sprent 1982), but it also be transferred to a secondary host (i.e., Malagasy boas) (Thompson 1994).However, direct infection of chameleons has also occurred experimentally using H. angusticaecoides larvae hatched from eggs, as well as larvae removed from Culex and other chameleons (Anderson 2000).
Relatively few host species have been identified for Hexametra angusticaecoides.Herein, we provide a list of all known hosts to date, and document a new host, the Madagascar Leaf-nosed Snake Langaha madagascariensis Bonnaterre, 1790 (Lamprophiidae).

Materials and methods
We obtained host species information from the literature.In August 2001, an adult (52.7 cm SVL, 33.1 cm tail length) female Langaha madagascariensis was collected in Madagascar and imported into Miami, Florida, United States.This snake was dead on arrival, salvaged for deposit in the Florida Museum of Natural History (FLMNH), University of Florida (UF 125922) (see Krysko 2003), and later dissected.

Results and discussion
We found that all known hosts of Hexametra angusticaecoides were confined to reptiles, including only lizards and snakes (Table 1).Our Langaha madagascariensis was found to be gravid, containing 12 oviducal eggs, and four H. angusticaecoides (one female, two males, and one third stage) within its digestive tract.
Our data provide the first documentation of Langaha madagascariensis as a host of Hexametra angusticaecoides.
Additionally, because the known paratenic hosts (mosquitos, midges, and cockroaches) of H. angusticaecoides are all extremely common in Florida, as well as Florida having the highest number of established non-native amphibians and reptiles in the entire world (Krysko et al. 2011), this should be of high concern to Florida biologists and conservationists.
All wild caught and imported reptiles should be subject to serial fecal examinations by a qualified individual and treated with a broad spectrum antihelminthic, such as those containing fenbendazole, if an infestation of Hexametra angusticaecoides is discovered.These animals should be quarantined and prophylactically dewormed due to extra-intestinal migration of the larvae and adults resulting in false negative fecal exam.Following the initial treatment, all animals should be subject to serial fecal examination to look for parasite shedding since initial treatment may be ineffective against extra-intestinal phases (Coke 1997).