Click on images to enlarge

Fig. 1. Oligonychus plegas paratype adult female - detail of a. claw I on left (and claw III on right); b. claw III; c-d. claw IV.

Fig. 2. Oligonychus plegas adult female paratype - detail of pregenital striae.

Fig. 3. Oligonychus plegas adult female (non-type, Australian) - detail of pregenital striae, and striae on genital flap.

Fig. 4. Oligonychus plegas paratype adult female - detail of peritreme tip (lower images are the same individual; arrows indicate tip).

Fig. 5. Oligonychus plegas adult female (non-type, Australian) - detail of peritreme tip (arrow indicates tip).

Fig. 6. Oligonychus plegas paratype adult female - detail of prodorsal striae.

Fig. 7. Oligonychus plegas adult female (non-type, Australian) - detail of striae and lobes on prodorsum.

Fig. 8. Oligonychus plegas paratype adult female - detail of pattern of striae between setae f1 and f2 (arrow indicates irregular oblique, transverse and longitudinal striae).

Fig. 9. Oligonychus plegas adult female (non-type, Australian) - detail of striae between setae f1 and f2, with irregular oblique, transverse and longitudinal striae.

Fig. 10. Oligonychus plegas adult female (non-type, Australian), detail of irregular striae between setae f1 and f2 (specimen not flat - two different focal points presented).

Fig. 11. Oligonychus plegas holotype adult male - detail of claw I.

Fig. 12. Oligonychus plegas paratype adult male - detail of claw I.

Fig. 13. Oligonychus plegas holotype adult male - detail of claw III.

Fig. 14. Oligonychus plegas holotype adult male - detail of claw IV.

Fig. 15. Oligonychus plegas holotype adult male - detail of peritreme tip (arrow indicates tip).

Fig. 16. Oligonychus plegas paratype adult male - detail of prodorsal striae.

Fig. 17. Oligonychus plegas adult male - detail of holotype and parataype aedeagus (at different focal points).

Fig. 18. Oligonychus plegas adult male holotype - detail of aedeagus at different focal points, from a. upper to f. lower.

Fig. 19. Oligonychus plegas paratype adult male - aedeagus (arrow indicates curved tip).

Fig. 20. Oligonychus plegas paratype adult male - aedeagus (arrows indicate curved tip).

Fig. 21. Oligonychus plegas adult males (non-type, Australia) - detail of aedeagus.

Fig. 22. Oligonychus plegas adult male (non-type, Australian) - detail of aedeagus at different focal points (arrow indicates curved tip).

Fig. 23. Oligonychus plegas adult male (non-type, Australian) - detail of aedeagus at different focal points (arrow indicates curved tip).

Material examined

types; non-types

Taxonomy

Subfamily Tetranychinae

Tribe Tetranychini

Common Name

none

Distribution

++Australia, Fiji, *Mauritius, New Caledonia, Papua New Guinea, Reunion, Vanuatu

Taxonomy Changes

none

Diagnosis

Female

• empodia I-IV = curved claw (Fig. 1)
• pregenital striae longitudinal (Figs 2, 3)
• tarsus I with the sockets of four tactile setae proximal to, and one solenidion proximal to or overlapping with, the socket of the proximal duplex seta
• tarsus II with the sockets of three tactile setae and one solenidion proximal to, and one tactile seta overlapping with, the socket of the duplex seta
• peritreme ending in simple unexpanded to slightly expanded bulb (Figs 4, 5)
• prodorsal striae longitudinal, forming a broad U-shape posteriorly (Figs 6, 7) 
• most dorsal striae transverse, except irregular oblique, transverse and longitudinal between opisthosomal setae f1-f1 and f1-f2 (Figs 8-10)
• chaetotaxy for legs I-IV:
  • femora 10, 6, 4, 4
  • genua 5, 5, 4, 4
  • tibiae 10(1+0), 7, 6, 7
  • tarsi 18(3+3), 16(2+3), 10(1+0), 10(1+0)

Male

• empodium I = bifid claw; dorsal claw shorter and more slender than ventral claw; dorsal claw not greatly separated from ventral claw (Figs 11, 12) 
• empodia II-IV with slender dorsal claw of equal length to proximoventral hairs, often with minute dorsal spur visible (Figs 13, 14)
• peritreme ending in simple slightly expanded bulb (Fig. 15)
• prodorsal striae longitudinal forming a U-shape posteriorly (Fig. 16)
• tarsus I with the sockets of four tactile and two solenidia proximal to, and one solenidion overlapping with, the socket of the proximal duplex seta
• tarsus II with the sockets of three tactile setae and one solenidion proximal to, and one tactile seta overlapping, the socket of the duplex seta 
• chaetotaxy for legs I-IV:
  • femora 10, 6, 4, 4
  • genua 5, 5, 4, 4
  • tibiae 13(4+0), 7, 6, 7
  • tarsi 20(5+3), 16(2+3), 10(1+0), 10(1+0)  [holotype has 19(5+3) on tarsus I]
• aedeagus dorsally directed, weakly sigmoid with one major bend and a small distal bend; no major anterior or posterior projection (dorsal projection directed posteriorly at very tip); dorsal margin of shaft at approx. 30° angle to ventral margin, abruptly bent dorsally at right angle forming dorsal projection; dorsal projection finger-like, abruptly tapering distally to narrow blunt tip; tip of dorsal projection curved posteriorly; ventral margin of shaft weakly convex to more or less straight (Figs 17-23)
• the tip of the dorsal projection of the aedeagus of holotype changes appearance at different focal points, from small curved tapered tip to straight tapered blunt  tip (see Fig. 17 - holotype illustration); all Australian specimens have a clearly curved tip (Figs 21-23)

Hosts

Various monocot hosts including: *Cocos nucifera (Arecaceae), Oryza sativa (Poaceae), Panicum maximum (Poaceae), Saccharum sp. (Poaceae), Zea mays (Poaceae)

Similar Taxa

Oligonychus aranaeum Davis 1968

Oligonychus digitatus Davis 1966

Oligonychus velascoi Rimando 1962

References

*Baker, E.W. and Pritchard, E.A. (1960) Tetranychoid mites of Africa.  Hilgardia 29(11): 455-574

Bolland, H.R., Gutierrez, J. and Helle, W. (1981)  Chromosomes in spider mites (Tetranychidae: Acari).  Acarologia 22(3): 271-275

Bolland, H.R., Gutierrez, J. and Flechtmann, C.H.W. (1998)  World catalogue of the spider mite family (Acari: Tetranychidae).  Brill Academic Publishers, Leiden, 392 pp.

Gutierrez, J. and Etienne, J. (1986)  Les Tetranychidae de l'ile de la Reunion et quelques-uns de leurs predateurs.  Agronomie Tropicale, Paris 41(1): 84-91

Gutierrez, J. and Schicha, E. (1984)  Phytoseiidae and Tetranychoidea in Fiji and other South Pacific islands (Acari).  International Journal of Entomology 26(4): 386-388

Migeon, A. and Dorkeld, F. (2006-2017) Spider Mites Web: a comprehensive database for the Tetranychidae. http://www.montpellier.inra.fr/CBGP/spmweb

Schicha, E. and Gutierrez, J. (1985)  Phytoseiidae of Papua New Guinea, with three new species, and new records of Tetranychidae (Acari).  International Journal of Acarology 11(3): 173-181

Notes

++ Not yet officially recorded in Australia.