Sphaerechinorhynchus macropisthospinus sp. n. (Acanthocephala: Plagiorhynchidae: Sphaerechinorhynchinae) is described from females with ovarian balls obtained from the house gecko, Hemidactlyus frenatus, and from 2 species of frogs. Kaloula pulchra and Microhyla sp. collected in the Doi Suthep-Pui National Park, suburban Chiang Mai, Thailand. One unidentified juvenile female now assigned the same species (this paper) was previously reported from the body cavity of the murrel fish, Ophicephalus striatus, also in Thailand. For a parasite that probably matures in snakes, the above represents an unusual assortment of paratenic host taxa that sheds some light on the possible biology of these unusual acanthocephalans. The new species is distinguished from the 3 other known species of the genus by having the largest number of proboscis hooks per row (9: 3 anterior rooted hooks and 6 spines) with the third (posteriormost) hook being the largest, among other features.