Material examined

not examined

Taxonomy

Subfamily Bryobiinae

Tribe Petrobiini

Common Name

none

Distribution

*Australia (Tasmania), The Netherlands, USA

Taxonomy Changes

none

Diagnosis

Female 

• empodium = stout claw with two tenent hairs (a single pair) 
• true claws = short pad with two tenent hairs
• reddish, convex rounded body
• leg I almost as long as body
• dorsum with coarse striae
• dorsal setae as long as distance to next seta
• peritreme a complex series of branches arising from a basal trunk
• legs with many short finely barbed tactile setae
• tarsus I with the sockets of 23 tactile setae and 6 solenidia proximal to the socket of the proximal duplex seta
• tarsus II with the sockets of 17 tactile setae and 1 solenidion proximal to the socket of the proximal duplex seta
• tibia I with 23 tactile setae (1 distinctly longer than others) and 1 solenidion
• tibia II with 17 tactile setae
• body large - approx. 870-900 long x 610-670 wide

Male as per female plus:

• body less rounded than female, striae less coarse than female
• leg I longer than body
• tarsus I with standard two pairs of duplex setae distally, PLUS another four pairs of duplex setae dorsally
• tarsus I with the sockets of 14 tactile setae and 21 sensory setae (solenidia) proximal to the sockets of the two pairs of standard distal duplex setae
• tarsus II with a single pair of duplex setae, and 20 tactile setae and sensory setae
• tibia I with 8 pairs of duplex setae along dorsal surface, 12 tactile setae (1 distinctly longer than others), 21 sensory setae and 1 short proximal sensory spine
• tibia II with 19 tactile setae
• femur I and genu I with thick barbed setae dorsally
• aedeagus long, slender, finely tapered, almost straight with slight upward curve
• body large - approx. 600 long x 400 wide

Hosts

Elymus repens (recorded as Elytrigia repens) (Poaceae), *Spergula arvensis (Caryophyllaceae)

(Womersley (1940) originally recorded the host as couch grass)

Similar Taxa

Schizonobiella Beer & Lang

Biology

Schizonobia sycophanta was originally collected from corn spurry Spergula arvensis (Caryophyllaceae) (although originally recorded as couch grass), on which their eggs were laid thickly congregated around the stems (Womersley 1940). This mite is widespread on corn spurry during the winter, and has not been collected on any other host in Australia.  During winter and early spring, all stages of the mite can be found on this host plant.  The species apparently aestivates as an egg since the active stages disappear during the summer but large numbers of eggs remain on the dried off stems of the host plants.  The eggs are red and spherical with white striations dorsally (Miller 1966).

References

Miller, L.W. (1966)  The tetranychid mites of Tasmania.  Papers and Proceedings of the Royal Society of Tasmania 100: 53-76

*Womersley, H. (1940)  Studies in Australian Acarina, Tetranychidae and Trichadenidae.  Transactions of the Royal Society of South Australia 64: 233-265

Notes

There is considerable variation in the number of duplex setae on male tarsus I and tibia I.  This species was described from Australia (Tasmania) on an introduced weed from Europe, corn spurry, Spergula arvensis (Caryophyllaceae).  Thus it is not entirely certain whether this species is actually native to Australia or not.