The Occurrence of the Strongylid Nematodes, (Nematoda: Diaphanocephalidae), in Viper Snakes, (Reptilia: Viperidae), Southwestern Iran.

ancylostomatid spp. is the common parasitic intestinal nematode of reptiles. West-Asian blunt-nosed viper is a venomous snake found in extensive areas of Iran. From June to September 2017, two dead viper snakes were referred to a parasitology laboratory and examined for intestinal parasites. Several white elongated roundworms were collected and fixed to identify under light and scanning electron microscopes (SEM) based on morphological and molecular characteristics. For the molecular survey, some parts of the identified worms were extracted and the ITS of nuclear ribosomal DNA (rDNA) was amplified by polymerase chain reaction (PCR). Five roundworms were found in one snake and three worms with similar morphological characteristics in another one. All the collected female hookworms were taxonomically identified as . The SEM findings showed the head was small and had three dorsal, ventral, and middle circumoral papillae with a spike-like process on the median papilla of . Moreover, the buccal capsule was bivalvular and included two lateral valves consisting of several chitonid pieces. The tail of the female worm was slim and long with a blunt end and had a terminal spike at its end. In the molecular survey, the ITS of rDNA amplified at about 850 bp was identified as . The ITS gene rDNA phylogeny analysis of the sequence showed that the isolated species had high similarity to species from around the world and is close to with 88% discrepancies in the phylogenetic tree. The morphological characteristics and a large part of rDNA nucleotide sequence were reported in viper snakes for the first time in the world and in Iran.