Figure 1.
Gordiid adults normally pair and mate in aquatic environments such as rivers, streams, lakes, and ponds. Ovipositioning begins within hours to days and can last as long as 2–3 weeks and produces several million eggs. Larvae hatch within 10–14 days, are non-buoyant, and do not swim. Upon consumption, using their proboscis, larvae penetrate and encyst within a wide variety of aquatic animals, including fish, snails, crustaceans, and aquatic insect larvae. Of these hosts, only aquatic insect larvae transport the cysts to the terrestrial environment after metamorphosis (dashed line), where the hosts and the cysts are consumed by the insect definitive host. Many hosts containing cysts, such as snails, which are not normally consumed by the definitive host, are considered dead-end hosts. Within the definitive host, cysts excyst and the larvae penetrate and develop within the hemocoel. Upon maturation, worms manipulate host behavior to jump into water, enabling the worms to make a successful transition from the terrestrial to the aquatic environment.
Figure 2.
Paragordius obamai n. sp. female laying eggs.
Female worm (brown) in the process of laying egg strings (white) containing eggs: (A) showing trilobed posterior end; (B) a worm and about 15% of total lifetime egg production. Scale bars = 2 mm.
Figure 3.
Paragordius obamai n. sp. cuticle.
(A) longitudinal ridges, from which long cuticular bristles emerge on the inside of the tail lobes, and (B) hemispherical structures on the mid-body surface. Abbreviations: PCR, parallel cuticular ridges; CB, cuticular bristles; HS, hemispherical structures. Scale bars = 10 µm.
Figure 4.
(A) free living larva and (B) cyst within Biomphalaria pfeifferi snail. Abbreviations: PS, pseudointestine; SPC, spine in crown; PRS, protruding spines. Scale bars = 10 µm.
Table 1.
Paragordius spp. distribution and the status of male descriptions for each species.
Table 2.
Gender of P. obamai n. sp. which emerged from three species of cricket host in the laboratory.