New Trematode Collyriclum Faba (Plagiochiida, Collyriclidae) Detected In The Birds Of Uzbekistan Author Azimov, D. A. Author Akramova, F. D. Author Shakarbaev, U. A. Author Azimov, N. N. text Zoodiversity 2021 2021-07-01 55 4 339 342 http://dx.doi.org/10.15407/zoo2021.04.339 journal article 55203 10.15407/zoo2021.04.339 ea5c3e04-c76b-496f-b84a-4302ed0d19c3 2707-7268 6377877 Collyriclum faba (Bremser in Schmalz, 1831) H o s t: mountain whitethroat — Sylvia althaea Hume, 1878 . L o c a l i s a t i o n: skin (the parasite was enclosed in cysts). Fig. 1. A mountain whitethroat ( Sylvia althaea ) with cysts infected with the trematode Collyriclum faba (Bremser in Schmalz, 1831). Surkhan State Reserve, Surkhandarya Province, south of Uzbekistan, June 2017 (photo by N. N. Azimov). L o c a t i o n: Uzbekistan (mountainous area within the Surkhan State Nature Reserve, Surkhandarya Province). Species description (based on original materials, 15 individuals of the trematode). Gentle, yellowish trematodes, rounded in shape, 4.98– 5.68 mm (5.27 ± 0.07) long and 4.88–5.46 mm (5.19 ± 0.05) wide. The cuticle is covered in places with thin thorns. The dorsal surface has on it a well-developed oral sucker, 0.362 –0.448 mm (0.399 ± 0.008) in diameter ( fig. 2 ). The yolk glands are composed of 6–8 follicles, arranged symmetrically in the front half of the body. The intestine occupies most of the body’s rear half. The seminal glands are oval, arranged symmetrically in the middle of the body, dorsally from the intestine’s branches. The heavily laciniate ovary is located in the front part of the body. The strongly developed womb lies in the rear part of the body and has the form of a broad sack at the end. The eggs are numerous, 0.0200 – 0.0220 mm (0.0214 ± 0.0001) long and 0.0140 –0.018 mm (0.0162 ± 0.0004) wide. Fig. 2. Collyriclum faba (Bremser in Schmalz, 1831), extracted from subcutaneous cysts in an infected individual of Sylvia althaea Hume, 1878 . The trematode’s morphometric parameters allowed us to identify it as Collyriclum faba . Cysts and mature Collyriclum faba found in the mountain whitethroat ( Sylvia althaea ) and other bird species ( Riley, 1931 ; Skrjabin, 1947 ; Stunkard, 1971 ; Blankespor et al., 1985; Kirmse, 1987 ; Literak et al., 2003 , 2006 , 2011; Mete et al., 2017 ) are almost identical throughout. The abovementioned slight variations may, probably, be attributed to the variability of some features depending on the host and geographical zone. Thus, the research helped identify the mountain whitethroat as a new host for the trematode C. faba , which is able to cause infection and subsequent death of heavily parasitised birds, which quite corresponds with the data published in earlier works ( Cole, 1911 ; Riley, 1931 ; Riley, Kernkamp, 1924 ; Buttner, 1951 ; Grove et al., 2005 ; Mete et al., 2017 ). The presented material complement to a certain extent the available data on the trematode C. faba and expand its range. The study of this unique species, C. faba , has a long history. Although the systematic position of the family Collyriclidae has been in the focus of parasitologists for over 100 years, this problem has not yet been solved. Opinions diverge and often contradict each other. This is confirmed by recently proposed trematode classifications, according to which the Collyriclidae are included in different taxons ( Bray et al., 2008 ; Taxonomy Browser, 2020 ). This situation has resulted mainly from insufficiency of data on the full cycle of development, the morphology and biology of parthenogenetic generations and C. faba ’s morphological variability in different hosts and geographic zones. These and other issues together with the contradictory opinions of various specialists require further research.