Ainsworth's salamander

Ainsworth's salamander is a very attenuated Plethodon with short limbs. It has 16 costal grooves, counting a Y-shaped groove in the groin as two grooves, and four to six costal folds between adpressed limbs. Its peritoneum is not distinctively pigmented. It has 40 premaxillary/maxillary teeth, and palatine teeth in a large median patch, 12 teeth wide and 18 teeth long. Vomerine teeth are in two well-separated, arc-shaped rows, with eight to 10 teeth each. As with all Plethodon species, this one has four digits on the manus and five on the pes, a cylindrical tail without any basal constriction, and a tongue attached in the front.[6]

In preservative, the specimens are dark blackish-brown without any noticeable pattern, and the peritoneum lacks any distinctive pigmentation.[6]

The holotype and paratype were collected by Jackson Harold Ainsworth as Plethodon glutinosus in 1964,[6] and described as a new species, Plethodon ainsworthi, by James Lazell in 1998.[3] No other specimens are known, and the precise collection locality is unknown.[1][5] The holotype is damaged, the paratype was damaged so strong that it is now lost. The distinctive features of this species, however, may result from long-term, improper preservation, suggesting that it is not a valid taxon.[5] P. mississippi exists in the area where P. ainsworthi is believed to have been collected.[5]

Its natural habitats were temperate forests and freshwater springs. Reasons for its extinction are unknown, but likely involved habitat loss via deforestation.[1]