Physaloptera rara		Contents		Rev 10/25/2025
		Classification		Biology and Ecology
		Morphology and Anatomy		Life Cycle
Return to Physaloptera  Menu				Ecosystem Functions and Services
		Distribution		Management
Return to Physalopteridae Menu		Feeding		References
		Go to Nemaplex Main Menu		Go to Dictionary of Terminology

Classification:

Back to Top

Morphology and Anatomy:

• Adult white to pink
• Mouth with two large, triangular lateral pseudolabia, each armed with teeth
• Large cervical collarette.
• No prepuce-like cuticular sheath covering the posterior end of the body as in P.praeputialis. .1 Female worms measure 27
  41 cm long 3 0.9
  1.1 mm wide. The vulva is located anterior to the middle of the body. Eggs are elliptical measuring 42
  53 3 29
  35 µm with a thick, clear smooth shell containing a coiled L1 when laid

Female:

•  Length 15-58 cm , width 1.0-1.7 mm.
• Vulva is located a little anterior to the mid-body.
• Eggs  elliptical , 45-58 x 30-42 um with thick, clear smooth shell containing an L1 when laid

Male:

• Length 25-29 mm, 800 um wide
• Spicules unequal length spicules (left 740-924 um, right 477-700 um long)

Ref  Marchiondo and Cruthers, 2020

Back to Top

Distribution:

North America. A spiruroid nematode infecting the stomach and duodenum of dogs, coyotes, raccoons, foxes, cats, and bobcats .

Back to Top

Feeding:

Infects stomach and duodenum of dogs, coyotes, raccoons, foxes, cats, and bobcats .

Back to Top/a>

Biology and Ecology:

Back to Top/a>

Life Cycle:

• Eggs of P. rara shed in the feces of a definitive host are immediately infective by to cockroaches, grain beetles, field crickets, and grasshoppers that serve as natural first intermediate hosts.
•  Larvae hatch in the midgut of the intermediate hosts and migrate to the wall of the intestine 36 h after ingestion.
•  The L1 molt to L2 between days 11 and 12, an anal plug in the L1 remains in place. The L2 molt to L3 by day 15.
• The L3 can live in crickets up to 152 days.
•  Frogs, snakes, birds, and mice serve as common paratenic hosts. Infected intermadiate host insects are eaten by paratenic hosts, the L3 migrate through the intestinal wall into the body cavity and encyst in organs and muscles. When dogs and other definitive hosts ingest an infected insect or paratenic host, the L3 develops to mature adults in the stomach and anterior duodenum.
• The prepatent period is 79 days from L3 in crickets and 75 days from L3 in rattlesnakes.

Ref: Marchiondo and Cruthers, 2020

Ecophysiological Parameters:

Back to Top

Ecosystem Functions and Services:

Back to Top

Management:

Back to Top

References:

Marchiondo, A.A., Cruthers, L.R. 2020. Nematoda, Spirurida. Chapter 2 in Marchiondo, Cruthers and Fourie (eds) Parasiticide Screening Vol 2. Academic Press

Copyright 1999 by Howard Ferris.
Revised: October 25, 2025.