CAUDAL POLYMORPHISM AND CEPHALIC MORPHOLOGY AMONG FIRST-STAGE LARVAE OF PARELAPHOSTRONGYLUS ODOCOILEI (PROTOSTRONGYLIDAE: ELAPHOSTRONGYLINAE) IN DALL'S SHEEP FROM THE MACKENZIE MOUNTAINS, CANADA

• Published in: The Journal of parasitology Vol. 91; no. 6; pp. 1318 - 1325
• Main Authors: Hoberg, Eric P, Jenkins, Emily J, Rosenthal, Benjamin, Wong, Mayee, Erbe, Eric F, Kutz, Susan J, Polley, Lydden
• Format: Journal Article
• Language: English
• Published: Lawrence, KS American Society of Parasitologists 01.12.2005; Allen Press Inc
• Subjects: Adults; Agriculture; animal morphology; animal parasitic nematodes; Animals; Biological and medical sciences; Conspecifics; COX-II gene; Cyclooxygenase 2 - genetics; Divergence; DNA, Helminth - chemistry; DNA, Intergenic - chemistry; DNA, Mitochondrial - chemistry; Feces; Female; Field emission microscopy; FUNCTIONAL MORPHOLOGY; Fundamental and applied biological sciences. Psychology; Gene sequencing; Genera; General aspects; General aspects and techniques. Study of several systematic groups. Models; Genomes; head; internal transcribed spacer-2; internal transcribed spacers; Invertebrates; Larva - genetics; Larva - ultrastructure; Larvae; Low temperature; Male; Mammalia; Metastrongyloidea - genetics; Metastrongyloidea - ultrastructure; Microscopy, Electron, Scanning - veterinary; Mitochondria; mitochondrial DNA; molecular systematics; Morphology; morphotypes; Mountains; Nematode larvae; Nematodes; Northwest Territories; nucleotide sequences; Ovis dalli; Papillae; Parasitology; Parelaphostrongylus; Polymerase chain reaction; Polymerase Chain Reaction - veterinary; Polymorphism; Polymorphism, Genetic; Protostrongylidae; Reagents; Scanning electron microscopy; Sheep; Sheep Diseases - parasitology; Specimens; Strongylida Infections - parasitology; Strongylida Infections - veterinary; tail; Tails; Temperature distribution; ultrastructure; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution; Zoology; Northwest Territories; Canada; North America; America; Northwest Territories Canada; California; United States > US; Mackenzie Mountains; Vertebrata; Mammalia; Ovis aries; Larva; Mountain; Morphology; Parasite; Sheep; Artiodactyla; Ungulata; Polymorphism
• ISSN: 0022-3395; 1937-2345
• DOI: 10.1645/GE-3503.1

We demonstrate polymorphism in the structure of the tail among first-stage larvae of Parelaphostrongylus odocoilei (Protostrongylidae). Two distinct larvae, both with a characteristic dorsal spine, include (1) a morphotype with a kinked conical tail marked by 3 distinct transverse folds or joints and a symmetrical terminal tail spike and (2) a morphotype with a digitate terminal region lacking folds or joints and with an asymmetrical, subterminal tail spike. These divergent larval forms had been postulated as perhaps representing distinct species of elaphostrongyline nematodes. Application of a multilocus approach using ITS-2 sequences from the nuclear genome and COX-II sequences from the mitochondrial genome confirmed the identity of these larvae as P. odocoilei. Additionally, based on scanning electron microscopy (low-temperature field emission), the cephalic region of these larvae consisted of a cuticular triradiate stoma surrounded by 6 single circumoral papillae of the inner circle, 10 papillae of the outer circle (4 paired and 2 single), and 2 lateral amphids. Our's is the first demonstration of structural polymorphism among larval conspecifics in the Metastrongyloidea and Strongylida. The basis for this polymorphism remains undetermined, but such phenomena, if discovered to be more widespread, may contribute to continued confusion in discriminating among first-stage larvae for species, genera, and subfamilies within Protostrongylidae.