Cyclocoelum Brandes, 1892

Dronen, Norman O. & Blend, Charles K., 2015, Updated keys to the genera in the subfamilies of Cyclocoelidae Stossich, 1902, including a reconsideration of species assignments, species keys and the proposal of a new genus in Szidatitreminae Dronen, 2007, Zootaxa 4053 (1), pp. 1-100 : 18

Key to the species of Cyclocoelum Brandes, 1892

1a. Rudimentary oral sucker absent.......................................................................... 2

1b. Rudimentary oral sucker present........................................................................ 4

2a. Uterus largely intercecal, posterior loops not reaching posterior margin of posterior testis.............................................................................. C. mutabile ( Zeder, 1800) (Syn. C. microstomum Creplin, 1829 )

2b. Uterine loops extensively overlapping the ceca laterally reaching nearly to body wall; posterior loops reaching posterior mar- gin of posterior testis................................................................................. 3

3a. Pharynx relatively wide, more than 1,000 µm; intertesticular space long, more than 2,500 µm, about 14% of body length.................................................................................. C. robustum Stossich, 1902

3b. Pharynx relatively narrow, 80–130 µm; intertesticular space relatively short, 1,500 µm or less, about 8% of body length................................................................................. C. microcotyleum Noble, 1933

4a. Uterine loops commonly overlapping ceca laterally.................................... C. macrorchis Harrah, 1922

4b. Uterus largely intercecal............................................................................... 5

5a. Eggs relatively large, greater than 130 µm long........................................ C. obscurum ( Leidy, 1887)

5b. Eggs relatively small, less than 130 µm long............................................................... 6

6a. Eggs exceptionally small, 90–93 µm x 47 –49 µm...................................... C. bikanerensis Gupta, 1964

6b. Eggs more moderately sized, 102 µm x 51 µm or larger...................................................... 7

7a. Cirrus sac relatively long, 1,200 µm or more, 8% or more of body length........... C. pseudomicrostomum Harrah, 1922

7b. Cirrus sac relatively short, 700 µm or less, 5% or less of body length........................................... 8

8a. Intertesticular space relatively short, 450–880 µm long, about 2–8% of body length................................................................................. C. leidyi Harrah, 1922 (Syn. Cyclocoelum cuneatum Harrah, 1922 )

8b. Intertesticular space relatively long, 3,000–5,800 µm, about 13–16% of body length.................................................................................. C. mehrotrai Sinha & Sahay, 1975 (Syn. C. mathuri Jain, 1984 )