No common name

Pseudodiplorchis americanus

ORDER

Polyopisthocotylea

FAMILY Polystomatidae

TAXONOMY

Pseudodiplorchis americanus Rodgers and Kuntz, 1940; Yamaguti, 1963.

OTHER COMMON NAMES

None known.

PHYSICAL CHARACTERISTICS

Length of adult about 0.31-0.39 in (8-10 mm). Haptor with six muscular suckers, each with an embedded hooklet. Sixteen hooklets. Fully developed, encapsulated oncomiracidia accumulate in huge uterus. Vitellarium greatly reduced. Pair of compact testes, positioned laterally in the anterior region of the body. Oral sucker present.

DISTRIBUTION

Deserts of Arizona, United States.

HABITAT

Bladder of spadefoot toad, Scaphiopus couchii. BEHAVIOR

No information available for adult.

FEEDING ECOLOGY AND DIET Feeds on blood.

REPRODUCTIVE BIOLOGY

Desert toad spends most of year buried about 3 ft (1 m) below surface of sand. Parasite in toad's bladder accumulates large numbers of eggs in uterus. Toads emerge following torrential annual rains; they spawn in temporary rain pools over a period of two or three nights. As toad enters pool, eggs of parasite are released and hatch immediately. Eggshell is reduced to thin membranous sac. Ciliated oncomiracidia are exceptionally large: 0.0236 in (600 pm) in length, compared to 0.00984 in (250 pm) for the oncomiracidia of Entobdella soleae. Larvae survive for 48 hours at 77-81°F (25-27°C). They attach to the toad, migrating over its skin to the nostrils. Larvae likely to be subjected to dehydration and high temperatures, but survive drying for up to one hour at 90°F (32°C) and 45% relative humidity. Period of development spent in lungs; then juveniles migrate through gut to bladder. Tegumental secretion probably protects migrating juvenile.

CONSERVATION STATUS

Not threatened.

SIGNIFICANCE TO HUMANS None known. ♦

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