We collected 21 individuals of the shovel-headed treefrog (Diaglena spatulata), a Mexican endemic species, from the states of Colima and Jalisco. Within this sample we documented the presence of the following parasites and commensals: a cestode (plerocercoid) of the order Proteocephalidea; adult nematodes of Aplectana, Cosmocercella diaglenae, Parapharyngodon chamelensis, and Physalopteroides bahamensis; and juvenile oligochaetes of Dero (Allodero). Our results extend the geographical distribution of C. diaglenae and P. chamelensis in Mexico and add four new records of species inhabiting this host. Additionally we recorded P. bahamensis and Dero (Allodero) for the first time in Mexico. Parapharyngodon chamelensis exhibited the highest infection levels, and levels were significantly higher in Jalisco than in Colima. The composition and abundance of parasites and commensals found in D. spatulata reflect the mainly insectivorous diet of this treefrog and show that aquatic habits exhibited during the breeding season (e.g., in temporary ponds) may play an important role in some of the infections.