Temnocephala, Blanchard, 1849

León, Rodrigo Ponce De, Rudolph, Erich H. & Volonterio, Odile, 2020, On a new Temnocephala (Platyhelminthes) from Southern Patagonia (Chile, Argentina), with a redescription of T. chilensis and some systematic and biogeographical insights *, Zootaxa 4852 (3), pp. 383-395 : 391-392

Key to the species of Temnocephala hosted on Aegla and Parastacidae

1. Introvert diameter more than 20 µm and with spines of different size............................................ 2

-. Introvert diameter less than 20 µm and with spines of similar size............................................... 4

2. Groove present between the introvert and the penial stylet............................................... T. dionii

-. Groove not present between the introvert and the penial stylet.................................................. 3

3. Introvert symmetrical and less than 45 µm in diameter......................................... T. monticellii n. sp. *

-. Introvert asymmetrical and more 45 µm in diameter................................................. T. chilensis *

4. Penial stylet length shorter than 190 µm ................................................................... 5

-. Penial stylet length 190 µm or longer..................................................................... 8

5. Ratio between introvert length and introvert width 1:1.5 or lower......................................... T. talicei

-. Ratio between introvert length and introvert width higher than 1:1.5............................................. 6

6. Penial stylet straight but with sinuous distal portion of shaft............................................. T. mertoni

-. Penial stylet slightly curved; distal portion of shaft not sinuous................................................. 7

7. Two distal vaginal sphincters................................................................... T. axenos *

-. One distal vaginal sphincter................................................................... T. mexicana *

8. Pharynx with posterior and anterior sphincters of equal width; seven internal spines in each spine-like projection of the introvert; stylet length range 200-258 (average 225); a single asymmetrical sphincter in the vagina............... T. gargantua

-. Pharynx with posterior sphincter much wider than the anterior one; nine or more internal spines in each spine-like projection of the introvert......................................................................................... 9

9. Nine internal spines in each spine-like projection of the introvert; stylet length range 195-212 (average 202); two sphincters in the vagina (proximal one asymmetrical).......................................................... T. grisella **

-. Fourteen-fifteen internal spines in each spine-like projection of the introvert; stylet length range 238-266 (average 256); a single asymmetrical sphincter in the vagina.................................................. T. cyanoglandula **

-. Nearly 11 internal spines in each spine-like projection of the introvert***; stylet length range 264-304 (average 280)............................................................................................... T. bresslaui **

* Temnocephala chilensis , T. axeno s, T. monticellii n. sp. and T. mexicana have also been reported on Parastacidae ( Dioni, 1967b, 1972; present work). Temnocephala mexicana has been reported in Cambaridae and Peudothelphusidae as well ( Lamothe-Argumedo, 1968, 1981; Martínez-Aquino et al., 2014).

** These three species share very similar shape and ratios of the penial stylet; the number of spines in each row of the introvert is here tentatively proposed as the strongest specific character to recognize them as distinct species. After the redescription of T. axenos made by Volonterio (2007a, b), Temnocephala bresslaui Pérez-González, 1949 is again considered a valid species.

*** Datum obtained from a figure of the article by Pérez-González (1949).