Family Molineidae Skrjabin & Schulz

1. Cephalic extremity with cuticular spines.................................................................... 2

- Cephalic extremity without cuticular spines................................................................. 5

2. Cephalic extremity with 2 large ventral spines............................................................... 3

- Cephalic extremity surrounded by ring of 8 large spines....................................................... 4

3. Cephalic spines side by side in ventral field................................................. Biacantha Wolfgang Species: B. desmoda Wolfgang, 1954; B. normaliae Oviedo, Ramallo & Claps in Oviedo, Ramallo, Claps & Miotti, 2012

- Cephalic spines opposite (in dorsal and ventral fields).......................... Websternema Vaucher & Durette-Desset Species: W. parnelli (Webster, 1971)

4. Anterior and posterior branches of ovejector vestibule similar in length............... Parahistiostrongylus Pérez Vigueras Species: P. octacanthus (Lent & Freitas, 1940) (also attributed to Stilestrongylus)

- Anterior branch of ovejector vestibule longer than posterior................................... Histiostrongylus Molin Species: H. coronatus Molin, 1861; H. paradoxus Travassos, 1918; Histiostrongylus sp.

5. Cephalic extremity with vesicle divided in two regions........................................................ 6

- Cephalic extremity with simple, undivided vesicle........................................................... 9

6. Posterior part of cephalic vesicle equal or longer than anterior part............................................... 7

- Posterior part of cephalic vesicle shorter than anterior part................................. Torrestrongylus Vigueras Species: Torrestrongylus sp.

7. Spicule undivided distally............................................................................... 8

- Spicule divided distally............................................................. Tricholeiperia Travasssos Species: T. leiperi Travassos, 1935; T. peruensis Vargas, Martinez, Tantaleán, Cadenilias & Pacheco, 2009; T. proencai Travassos, 1937

8. Dorsal ray of male copulatory bursa long and divided in distal third; ovejector of female without spines................................................................................................ Anoplostrongylus Boulenger Species: A. paradoxus (Travassos, 1918)

- Dorsal ray of male copulatory bursa short and deeply divided; ovejector of female with spines............................................................................................. Molostrongylus Durette-Desset & Vaucher Species: M. acanthocolpos Durette-Desset & Vaucher, 1996; M. mbopi Durette-Desset & Vaucher, 1999

9. Tail of female without appendices/tubercles.......................................... Cheiropteronema Sandground Species: C. globocephala Sandground, 1929; C. striatum Oviedo, Ramallo & Claps, 2010; Cheiropteronema sp.

- Tail of female with appendices/tubercles.................................................................. 10

10. Tail of female with two appendices..................................................... Bidigiticauda Chitwood Species: B. embryophilum (Freitas & Dobbin Jr., 1960 (a)); B. vivipara Chitwood, 1938

- Tail of female with five to seven tubercles................................. Carostrongylus Durette-Desset & Vaucher Species: C. touzeti Durette-Desset & Vaucher, 1989