Towards resolving the problematic status of the digenean genus Astiotrema Looss, 1900: An updated concept and revision of species composition for Astiotrema (sensu stricto)

Abstract

Species of Astiotrema Looss, 1900 (sensu lato) infect a wide range of fishes, amphibians and reptilians. They also possess a considerably wide spectrum of morphological features. Several species were recognized for variable, confusing, overlapping and unspecialized morphological characters rather than for unique distinguishing features, causing continuing dispute around the validity of several species. Following comprehensive review, a revised restricted concept of Astiotrema is proposed including a morphologically strict definition. Both Tremiorchis Mehra & Negi, 1926 and Astioglossimetra Bilqees, Khatoon & Khan, 2002 are synonymized with Astiotrema (sensu stricto). Several nominal species are synonymized, others are excluded and characters for each recognized species are presented and explained. Only eight species are recognized: Astiotrema cyclemysi Siddiqi, 1965, Astiotrema emydis Ejsmont, 1930, Astiotrema fotedari Dhar, 1977, Astiotrema impletum (Looss, 1899) Looss, 1900, Astiotrema karachiensis (Bilqees, Khatoon & Khan, 2002) n. comb., Astiotrema odhneri Bhalerao, 1936, Astiotrema ranarum (Mehra & Negi, 1926) Fotedar, 1971 and Astiotrema reniferum (Looss, 1898) Looss, 1900. A key to the species of Astiotrema (sensu stricto) is presented, a comprehensive list of all host-locality records is included and host-parasite specificity is elucidated.

Cercarial dermatitis outbreak caused by ruminant parasite with intermediate snail host: schistosome in Chana, South Thailand

“…The genus Astiotrema, which belongs to the Plagiorchiidae, represent trematodes infecting a wide range of fishes, amphibians, and reptilians. Many reports have indicated that Astiotrema (sensu stricto) is widely spread throughout Asia, Europe, and Africa, particularly in northeastern Africa (Egypt, Sudan), eastern Asia (China, southern Korea), southern Asia (India, Pakistan), southeastern Asia (Myanmar), northern Asia (Russia), and central Europe (Poland) (Karar et al 2021). However, several authors were unclear as to the diagnostic features of Astiotrema used, which are considered to be highly variable.…”

Molecular identification of trematode parasites infecting the freshwater snail Bithynia siamensis goniomphalos in Thailand

“…The 28S sequence of our cercaria (ON312624) matched those of species in the genus Astiotrema Looss, 1900 and of Tremiorchis ranarum Mehra & Negi, 1926 (MT218013) at over 96% of sites. Tremiorchis Mehra & Nega, 1926 is often regarded as a junior synonym of Astiotrema (see Karar et al ., 2021; Shinad et al ., 2021). The next-best 28S matches were much lower (~87%) and were with campulids, brachycladiids and acanthocolpids, none of which is a likely home for this cercaria.…”