Anchitrema Looss, 1899

Dronen, Norman O., Karar, Yasser F. M. & Blend, Charles K., 2020, A new genus and species of Anchitrematidae Mehra, 1935 (Digenea: Gorgoderoidea) in a freshwater fish from the River Nile at Qena, Egypt with amendation of the family, Zootaxa 4780 (2), pp. 367-378 : 371

Key to the species of Anchitrema Looss, 1899

1a. Body relatively large, some 6,000 long; oral sucker/pharynx width ratio ≥1:3.0.............................................................................................. Anchitrema sanguineum ( Sonsino, 1894) Looss, 1899

1b. Body relatively small, less than 4,500 long (1,300 –4,335); oral sucker/pharynx width ratio ≤ 1:2.9 (i.e., 1: 1.4–1: 2.9)..... 2

2a. Testes located less than one-third of body length from anterior end (27–30% of body length); uterine loops commonly overlap vitelline fields and may reach outer margins of testes laterally.................................................. 3

2b. Testes located more than one-third of body length from anterior end (35–40% of body length); few to no uterine loops overlap vitelline fields and do not reach outer margin of testes laterally................................................. 4

3a. Testes smooth; ovary median, immediately posterior to testes; eggs small, 20–24 × 11–16............... Anchitrema latum Gedoelst, 1919 ; syns. Anchitrema congolense ( Sandground, 1937) Yamaguti, 1958 , Platynosomum philippinorum congolensis Sandground, 1937 , Anchitrema philippinorum congolensis ( Sandground, 1937) Skarbilovich, 1948

3b. Testes distinctly lobed; ovary submedian, inter-testicular at level of posterior one-third of testes; eggs large, 32 × 19............................... Anchitrema sokolowi ( Skrjabin, 1916) Dollfus, 1929 ; syn. Mesocoelium sokolowi Skrjabin, 1916

4a. Body notably elongate, narrow (width <15% of body length; i.e., 12–14%); ovary contiguous with posterior end of testes; testes contiguous..................................................... Anchitrema longiformis Saoud & Ramadan, 1977

4b. Body elongate-oval to lingulate, broad (width>20% of body length; i.e., 24–42%); ovary post-testicular; inter-testicular space distinct............................................................................................. 5

5a. Forebody relatively short (23–30% of body length); oral sucker/pharynx width ratio relatively small (1:1.4–1:1.5); inter-testicular space relatively large (10–12% of body length)...... Anchitrema indicum ( Thapar, 1958) Pande, 1935 ; syns. Anchitrema lucknowensis Agrawal , 19661, Exorchocoelium indicum Thapar, 1958

5b. Forebody relatively long (approx. 40% of body length); oral sucker/pharynx width ratio relatively large (1:2.2–1:2.5); intertesticular space relatively small (approx. 6% of body length).......................................................... Anchitrema philippinorum ( Tubangui, 1928) Skarbilovich , 19482; syn. Platynosomum philippinorum Tubangui, 1928