Leioseius

Santos, Jandir C. & De Moraes, Gilberto J., 2016, A new species of Leioseius (Acari: Ascidae) from Brazil, redescription of Leioseius basis and a key for separation of the world species of the genus, Zootaxa 4158 (1) : -

Key to the world Leioseius species (based on females)

Leioseius setosulus ( Berlese, 1916) was not included in the key because of insufficient information about this species in the literature. Leioseius codrensis Pinchuk, 1972 was transferred to Digamasellidae by Moraes et al. (2016). Specimens reported by Schweizer (1949, 1961) as Leioseius venustulus ( Berlese, 1916) were considered by Hirschmann (1962) as Iphidozercon schweizeri and mentioned by Moraes et al. (2016) as a species incertae sedis.

1. Dorsal shield with lateral incisions (between podonotal and opistonotal region).................................... 2

- Dorsal shield without lateral incisions.................................................................... 17

2. Ventrianal shield with 2–3 pairs of opisthogastric setae in addition to circumanal setae.............................. 3

- Ventrianal shield with 4–6 pairs of opisthogastric setae in addition to circumanal setae............................. 11

3. Ventrianal shield with two pairs of opisthogastric setae in addition to circumanal setae.............................. 4

- Ventrianal shield with three pairs of opisthogastric setae in addition to circumanal setae............................. 6

4. With a pair of metapodal plates; lateral margin of dorsal shield with shallow incision anteriad of S 1 (barely reaching level of Z 1); with a single pair of Jv setae between genital and ventrianal shield....... Leioseius minusculus ( Berlese, 1905) ; Italy

- With two pairs of metapodal plates; lateral margin of dorsal shield with deep incision anteried of S 1 (reaching well beyond level of Z 1); with two pairs of Jv setae between genital and ventrianal shield...................................... 5

5. Seta Z 5 longer than distance between its base and the base of J 5 of the apposite side; post-anal seta slightly longer than dis- tance between its base and base of Jv 5 (longest among the opisthogastric setae on ventrianal shield) of the same side......................................................................... Leioseius dolichotrichus Ma, 2002 ; China

- Seta Z 5 much shorter than distance between its base and base of J 5 of the opposite side; post-anal seta much shorter than dis- tance between its base and base of Jv 5 of the same side..................... Leioseius mirabilis Nikolsky, 1981 ; Russia

6. Setae st 2 absent..................................................... Leioseius californicus Chant, 1963 ; USA

- Setae st 2 present..................................................................................... 7

7. With three pairs of metapodal plates.................................. Leioseius brevisetosus Ishikawa, 1969 ; Japan

- With one pair of metapodal plates....................................................................... 8

8. Post-anal seta about as long as para-anal setae.............................................................. 9

- Post-anal seta 1.8–2 times as long as para-anal setae........................................................ 10

9. With four of transversely aligned elongate platelets anteriad of a pair of rounded platelets between genital and ventrianal shield; lateral margins of genital shield distinctly divergent posteriorly with a pair of notches posteriad of st 5......................................................................... Leioseius changbaiensis Yin & Bei, 1991 ; China

- With a pair of aligned elongate platelets between genital and ventrianal shield; lateral margin of genital shield slightly diver- gent posteriorly, without notches posteriad of St 5.......................... Leioseius elongatus Evans, 1958 ; England

10. Setae Jv 4 off and Jv 5 on ventrianal shield, which is not constricted between levels of para-anal and post-anal setae................................................................ Leioseius montanulus ( Hirschmann, 1962) ; not stated

- Setae Jv 4 on and Jv 5 off ventrianal shield, which is constricted between levels of para-anal and post-anal setae............................................................................... Leioseius lanzhouensis Ma, 2008 ; China

11. Ventrianal shield with 4–5 pairs of opisthogastric setae in addition to circumanal setae............................. 12

- Ventrianal shield with six pairs of opisthogastric setae in addition to circumanal setae............................. 14

12. Ventrianal shield with five pairs of opisthogastric setae in addition to circumanal setae........................................................................................... Leioseius littorale Womersley, 1961 ; New Guinea

- Ventrianal shield with four pairs of opisthogastric setae in addition to circumanal setae............................ 13

13. Opisthonotal region of dorsal shield and posterior half of ventrianal shield mostly punctate; seta Z 5 smooth................................................................................. Leioseius salinus ( Halbert, 1920) ; Ireland

- Opisthonotal region of dorsal shield and posterior half of ventrianal shield reticulate; seta Z 5 distinctly serrate............................................................................. Leioseius naglitschi Karg, 1965 ; Germany

14. Dorsal shield reticulate, each reticle formed by sinuous and punctate lines; unsclerotised cuticle laterad of dorsal shield with six pairs of setae........................................ Leioseius quinquesetosus Athias-Henriot, 1959 ; Algeria

- Dorsal shield smooth; unsclerotised cuticle laterad of dorsal shield with 0–4 pairs of setae......................... 15

15. Post-anal seta about three times as long as of para-anal setae............... Leioseius vallaensis Luxton, 1989 ; Australia

- Post-anal seta about as long as para-anal setae............................................................ 16

16. Incisions between podonotal and opisthonotal regions of dorsal shield reaching level of z–Z series; fixed cheliceral digit with six teeth in addition to apical tooth........................................... Leioseius cananeiensis n.sp; Brazil

- Incisions between podonotal and opisthonotal regions of dorsal shield reaching only level of s–S series; fixed cheliceral digit with two teeth in addition to apical tooth............................ Leioseius australis Luxton, 1984 ; New Zealand

17. Most dorsal idiosomal setae dagger-shaped; ventrianal shield with six pairs of opisthogastric setae in addition to circumanal setae............................................................... Leioseius basis Karg, 1994 ; Galapagos

- Most dorsal idiosomal setae aciculate; ventrianal shield with 2–3 pairs of opisthogastric setae in addition to circumanal setae.................................................................................................. 18

18. Ventrianal shield with two pairs of opisthogastric setae in addition to circumanal setae; central extension of epistome distinctly longer than lateral extensions, club-shaped..................................... Leioseius clatri Karg, 1977 ; Chile

- Ventrianal shield with three pairs of opisthogastric setae in addition to circumanal setae; central extension of epistome about as long as lateral extensions, sharp-tipped........................... Leioseius elegantulus Schweizer, 1949 ; Switzerland