Pachyseius

Özbek, Hasan Hüseyin & Halliday, Bruce, 2014, Two new species of Pachyseius Berlese (Acari: Pachylaelapidae) from Turkey, with a key to the world species, Zootaxa 3841 (1), pp. 107-116 : 113-114

Key to females of the world species of Pachyseius

The published descriptions of some species are ambiguous in their treatment of some important character states. Pachyseius chenpengi Ma & Yin, 2000 was described and illustrated as having two setae on one side of the ventrianal shield and three on the other side, on the basis of only two specimens. It is impossible to assess the significance of this asymmetry with this limited number of specimens. Pachyseius sinicus Yin et al., 1986 was described as having four pairs of setae on the ventri-anal shield, but two of these pairs are on the extreme lateral edges of the shield, where their positions may show intra-specific or artificial variation, again on the basis of only two specimens. The description of Pachyseius huanrenensis Chen et al., 2009 states that the genital setae are situated on the epigynal shield, as would be normal for the genus. The illustration shows the genital setae inserted in the soft skin outside the epigynal shield, but this appears to be an error. These character states will need to be confirmed when larger collections of these species are examined. Because of the ambiguous position of the ventrianal setae in some species, we have not used this character as the only means of diagnosing those species in the key. Most of the information in the key was taken from published descriptions and illustrations, not directly from examination of specimens.

1. Anterior margin of sternal shield with a pair of pointed horn-like projections anterior to setae st1 ...................... 2

- Anterior margin of sternal shield straight or curved, but without a pair of horn-like projections........................ 5

2. Most dorsal shield setae with expanded spatulate tips.................................. P. cavernicola Ishikawa, 1989

- All dorsal shield setae fine, pointed, needle-like............................................................. 3

3. Anterior dorsal shield setae long; j3 longer than distance j3–j4; j4 longer than distance j3–j4; z5 longer than distance z5–z6 ...

............................................................................ P. sinicus Yin, Lu & Lan, 1986 - Anterior dorsal shield setae short; j3 shorter than distance j3–j4; j4 shorter than distance j3–j4; z5 shorter than distance z5–z6 4

4. Anterior margin of epistome serrated, truncate; small species, length described as 526 μm; opisthogastric soft skin lateral to ventri-anal shield with seven pairs of setae; dorsal shield setae z1, j2 short, less than half length of j1 ......................................................................................... P. huanrenensis Chen, Bai & Gao, 2009

- Anterior margin of epistome serrated, triangular, produced into a sharp point; large species, length described as 689 μm; opist- hogastric soft skin lateral to ventri-anal shield with five pairs of setae; dorsal shield setae z1, j2 long, more than half length of j1........................................................................... P . chenpengi Ma & Yin, 2000

5. Metasternal plates fused with sternal shield to form a sternal-metasternal complex bearing four pairs of setae........................................................................................ P. morazae Mašán & Mihál, 2007

- Metasternal setae on separate metasternal plates, sternal shield with three pairs of setae.............................. 6

6. Metapodal plates small and oval, fused with and partly enclosed by edges of ventri-anal shield.................................................................................................... P. strandtmanni Solomon, 1982

- Metapodal plates much longer than wide, not fused to ventri-anal shield, posterior ends may be abutting ventri-anal shield.. 7

7. Metapodal plates abutting ventri-anal shield at their posterior ends............................................... 8

- Metapodal plates clearly separate from ventri-anal shield...................................................... 9

8. Ventri-anal shield with two pairs of pre-anal setae; central opisthonotal setae long; J2 and J3 subequal to J4 ............................................................................................ P. orientalis Nikolsky, 1982

- Ventri-anal shield with three pairs of pre-anal setae; central opisthonotal setae short; J2 and J3 less than half length of J4 .............................................................................. P. wideventris Afifi & Nasr, 1984

9. Pre-sternal area smooth or weakly granulate-reticulate; anterior margin of this weakly sclerotised area may be more distinct, but always connected to sternal shield by an area of granular ornamentation...................................... 10

- Pre-sternal area with a pair of well-defined sclerotised pre-sternal plates, clearly separated from sternal shield by a strip of unsclerotised soft skin1................................................................................. 8

10. Metapodal plates greatly expanded and ornamented, widest anteriorly, their anterior ends abutting exopodal plates IV.......................................................................... P. pachylaelapoides Mašán & Mihál, 2007

- Metapodal plates long and narrow, not greatly expanded, widely separated from ventri-anal and expodal shields......... 11

11. Ventri-anal shield with three pairs of pre-anal setae, Jv1, Jv2, Zv2, all clearly within margins of shield................. 12

- Ventri-anal shield with two pairs of pre-anal setae, Jv1, Jv2 ................................................... 15

12. Almost all dorsal shield setae slightly spatulate............................................ P. iraola Moraza, 1993

- All dorsal shield setae fine and needle-like................................................................. 13

13. Ventri-anal shield triangular, widest anterior to setae Jv2.................................. P . humeralis Berlese, 1910

- Ventri-anal shield oval-shaped, widest posterior to setae Jv2 ................................................... 14

14. Anterior dorsal shield setae short; j3 not long enough to reach j2 or edge of shield, z2 not long enough to reach edge of shield; anterior end of peritreme clearly extending beyond gdj3; ornamentation on ventri-anal shield punctate-lineate over entire shield................................................................................. P. masani sp. nov.

- Anterior dorsal shield setae long; j3 long enough to reach j2 and edge of shield, z2 long enough to reach edge of shield; anterior end of peritreme level with gdj3; ornamentation on ventri-anal shield very faint or absent in central area of shield............................................................................................ P. slavicus Mašán, 2007

15. Ventri-anal shield narrow anteriorly, widest posterior to setae Jv2...................... P . angustiventris Willmann, 1935

- Ventri-anal shield wide anteriorly, narrower posterior to setae Jv2 .............................................. 16

16. Peritrematal shields short, posterior ends at mid-level of coxae IV and exopodal plates IV......... P. morenoi Moraza, 1993

- Peritrematal shields long, posterior ends extending beyond posterior level of coxae IV, level with posterior margin of exopodal plates IV........................................................................................... 17

17. Anterior half of ventri-anal shield clearly wider than posterior half, its postero-lateral margins concave................................................................................................... P. friedrichi Mašán, 2008

- Anterior half of ventri-anal shield only slightly wider than posterior half, its lateral margins convex.. P. angustus Hyatt, 1956

18. Posterior end of peritrematal shield fused to exopodal plate IV.......................... P. cicaki Mašán & Mihál, 2007

- Posterior end of peritrematal shield not fused to exopodal plate IV.............................................. 19

19. Ventri-anal shield with two pairs of pre-anal setae (Jv1, Jv2); dorsal shield seta j1 long, more than double length of z1 ........................................................................................... P. siranensis sp. nov.

- Ventri-anal shield with three pairs of pre-anal setae (Jv1, Jv2 and Zv2); dorsal shield seta j1 short, subequal to z1 ................................................................................. P. crymophilus Mašán & Fenďa, 2014