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Fig. 1. Oligonychus digitatus adult female - detail of empodia.

Fig. 2. O. digitatus adult female - detail of the pattern of pregenital striae.

Fig. 3. O. digitatus adult female - detail of the pattern of pregenital striae.

Fig. 4. O. digitatus adult female - detail of peritreme (arrows indicate the simple bulb).

Fig. 5. O. digitatus adult female - detail of the pattern of dorsal striae between setae e1 and f1.

Fig. 6. O. digitatus adult female - detail of the pattern of dorsal striae between setae e1 and f1.

Fig. 7. O. digitatus adult male - lateral habitus.

Fig. 8. O. digitatus adult male - detail of empodium I.

Fig. 9. O. digitatus adult male - detail of empodia.

Fig. 10.   O. digitatus adult male - detail of aedeagus (lateral and dorsal aspects).

Material examined

types

Taxonomy

Subfamily Tetranychinae

Tribe Tetranychini

Distribution

*Australia: south eastern Queensland, New South Wales

Taxonomy Changes

None

Diagnosis

Female

• empodia I-IV long slender curved claw (Fig. 1) 
• pregenital striae usually with patches of irregular oblique and longitudinal striae (Figs 2, 3) 
• peritreme ending in simple bulb with little or no expansion (Fig. 4)
• most dorsal striae transverse, except irregular longitudinal and oblique between opisthosomal setae f1 and f2 (Figs 5, 6)
• tarsus I with the sockets of four tactile setae proximal to the socket of the proximal duplex seta
• chaetotaxy for legs I-IV:
  • femora 9-10, 6, 4, 4
  • genua 5, 5, 4, 4
  • tibiae 10-11(1 -2+0), 7, 6, 7
• pale yellow
• copious dense webbing produced

Male (Fig. 7)

• empodium I = bifid claw, ventral claw longer than dorsal spur/claw (Fig. 8) 
• empodia II-IV with dorsal claw shorter than proximoventral hairs (Fig. 9)  
• peritreme ending in simple bulb with little or no expansion (Fig. 4)
• tarsus I with sockets of four tactile and one-two solenidia proximal to the socket of the proximal duplex seta
• chaetotaxy for legs I-IV:
  • femora 10, 6, 4, 4
  • genua 5, 5, 4, 4
  • tibiae 12-13(3-4+0), 7, 6, 7
• aedeagus dorsally directed, abruptly upturned at slight angle back over shaft, broad basally and abruptly tapered distally to form short finger-like blunt tip; posterior margin strongly convex (Fig. 10)

Hosts

Cynodon dactylon, *Digitaria didactyla, *Pennisetum clandestinum, Stenotaphrum secundatum (Poaceae)

Similar Taxa

Oligonychus araneum Davis 1968

Oligonychus plegas Baker & Prtichard 1960

Oligonychus velascoi Rimando 1962

Biology

Oligonychus digitatus can occur in very large populations that cause yellowing of grass in a ring-shaped area as the colony grows and spreads outwards from the initial infestation which turns brown (Davis 1966). 

References

*Davis, J.J. (1966)  Studies of Queensland Tetranychidae. I. Oligonychus digitatus sp. n. (Acarina: Tetranychidae), a spider mite from grasses.  Queensland Journal of Agricultural and Animal Sciences 23: 569-572