Stenostomum, AND, AND

Noreña, Carolina, Damborenea, Cristina & Brusa, Francisco, 2005, A taxonomic revision of South American species of the genus Stenostomum O. Schmidt (Platyhelminthes: Catenulida) based on morphological characters, Zoological Journal of the Linnean Society 144 (1), pp. 37-58 : 55

KEY TO THE SOUTH AMERICAN SPECIES OF THE GENERA STENOSTOMUM AND ANOKKOSTENOSTOMUM

1. With light-refracting bodies....................... Genus Stenostomum ..............................2 Without light-refracting bodies.................... Genus Anokkostenostomum .....................15

2. Light-refracting bodies type 1 (disc shaped with more than ten small spheres).............................3 Light-refracting bodies type 2 (bowl shaped with one to five spheres).....................................7 Light-refracting bodies type 3 (single-granule bodies, with no vesicle)............................ S. simplex

3. Pharyngeal glands type a (small rounded glands).....................................................4 Pharyngeal glands types a and b (rounded and club shaped)............................................6

4. Pharyngeal glands uniformly arranged in the whole pharynx................................ S. tenuicauda Pharyngeal glands only in the anterior half of the pharynx.............................................5

5. With sphincter between pharynx and intestine, oral pore circular................................. S. grande Without a sphincter between pharynx and intestine, oral pore triangular...................... S. matarazzoi

6. Without a sphincter between pharynx and intestine, opening of pharyngeal glands along the whole pharynx........................................................... S. leucops With a sphincter between pharynx and intestine, opening of the pharyngeal glands at the anterior half of the pharynx, internal cerebral lobes associated with the posterior cerebral lobes........................................................ S. amphotum

7. One pair of light-refracting bodies. No caecum dorsal to the pharynx.....................................8 More than one pair of light-refracting bodies. No caecum dorsal to the pharynx...........................12 One or more pairs of light-refracting bodies. Intestinal caecum dorsal to the pharynx............... S. cryptops

8. Posterior end with no intestine-lacking zone.........................................................9 Posterior end with intestine-lacking zone........................................................... 10

9. Pharyngeal glands type a (small rounded), opening uniformly onto the whole pharynx.......... S. virginianum Pharyngeal glands type b (club shaped), opening at the transition between mouth and pharynx........................................................ S. hemisphericum

10. Distal end of the protonephridium straight, and subterminal nephridiopore....................... S. ciliatum Distal end of the protonephridium sinuous and terminal nephridiopore..................................11

11. First part of the intestine with high vacuolated cells, separated from the gut by a strong constriction..................................................... S. rosulatum Without vacuolated cells in the gut, pharynx glands type b (club shaped)..................... S. uronephrium

12. Light-refracting bodies associated only with the anterior brain lobes....................................13 Light-refracting bodies associated with both anterior and posterior brain lobes...........................14

13. Posterior end with intestine-lacking zone. Tail with two appendages. With tentacular pharyngeal organ (‘claw-organ’).......................................... S. bicaudatum

Posterior end with no intestine-lacking zone. Epidermis with groups of refractive corpuscles................................................................. S. glandulosum

14. Tail simple (one appendage)............................................................... S. arevaloi Tail double (two appendages)......................................................... S. paraguayense

15. Posterior end with intestine-lacking zone, with simple tail.............................................16 Posterior end with no intestine-lacking zone........................................................18

16. Tail very long forming a dorsal appendage. Nephridiopore subterminal.................. A. pseudoacetabulum Tail short. Nephridiopore terminal................................................................ 17

17. Excretophores absent. Type b (club-shaped) pharyngeal glands No sphincter between pharynx and intestine............................................ A. tuberculosum

Excretophores present. Type a (rounded) pharyngeal glands. With sphincter between pharynx and intestine............................................ A. pegephilum

18. With excretophores............................................................................. 19 Without excretophores............................................................ A. ventronephrium

19. Smooth anterior cerebral lobe. Intestinal caecum dorsal to the pharynx........................... A. evelinae Anterior cerebral lobe with small independent masses................................................20

20. Anterior end ‘anatiform’............................................................. A. anatirostrum Anterior end not ‘anatiform’. Pharyngeal glands in the anterior region only....................... A. corderoi