Tetranychus, Dufour, 1832

SEEMAN, OWEN D. & BEARD, JENNIFER J., 2011, Identification of exotic pest and Australian native and naturalised species of Tetranychus (Acari: Tetranychidae), Zootaxa 2961 (1), pp. 1-72 : 13-21

Key to Tetranychus : naturalised Australian species and exotic species of quarantine concern to Australia

Female and male mites are required for this key. Males must be mounted laterally. A plate of line drawings of aedeagi is provided at the end of the key ( Fig. 9 ), but we urge users to employ characters other than the aedeagus for identifications, where possible.

This key is a modification of several existing keys, notably Baker & Tuttle (1994) and Flechtmann and Knihinicki (2002). Species in bold are not known from Australia. Unlabelled scale bars are 50 µm.

Notes: 1. Some T. lambi will key to couplet 21 but females of this species have entire pregenital striae sometimes with lobes. 2. Couplet 10, the number of proximal setae overlapping with the proximal duplex setae varies. Where possible, examine several specimens and look at both left and right tarsi. 3. Some T. marianae will key to couplet 12 but have a high ∑d prox value and different form of the aedeagus. 4. T. gloveri was recently detected—and eradicated—in Darwin (L. Zhang, personal communications).

1 Female: Empodia with 2 pairs of proximoventral hairs, the dorsal being much smaller than the ventral (1a); dorsal empodial spur present. Male: aedeagus very long and tapered (1c)........................................... T. fijiensis Hirst

- Female: Empodia with 3 pairs of proximoventral hairs (1b); dorsal empodial spur present or absent. Male: aedeagus usually with an apical knob (1d), if without apical knob then aedeagus not very long..................................... 2

2 Female: Pregenital striae entire and irregular, comprising oblique and longitudinal sections (2a). Known only from Rhagodia sp. (Chenopodiaceae) in Tasmania ......................................................... T. rhagodiae Miller

- Female: Pregenital striae entire (2b) or broken (2c), sometimes nearly absent medially, but comprising only longitudinal striae................................................................................................... 3 3 Female: Dorsal hysterosomal striae entirely transverse, no longitudinal striae present (3a)........................... 4

- Female: Dorsal hysterosomal striae with at least some longitudinal or oblique striae, usually between setae f1–f1 and/or e1–e1 (3b, 3c)............................................................................................ 5

4 Male: Aedeagus strongly sigmoid, tapering strongly distally, without a distinct apical knob (4a). Female: Pregenital striae a mixture of broken and solid lines (4c); dorsal striae mostly without lobes...................... T. mcdanieli McGregor

- Male: Aedeagus angular, with large tapered posterior projection, anterior projection small, angular (4b). Female: Pregenital striae irregular and vague (4d); dorsal striae with lobes...................................... T. pacificus McGregor

5 Female: Tarsus III with 2 proximal tactile setae (total of 10 setae + 1 solenidia); lobes absent on ventral striae. Male: Knob of aedeagus large, 2–3x the width of the neck; posterior projection and often anterior projection long, its length longer than the width of the neck (5a)............................................................. T. mexicanus (McGregor)

- Female: Tarsus III with 1 proximal seta (total of 9 setae + 1 solenidia); lobes present or absent on ventral striae. Male: Knob of aedeagus variable in size and form..................................................................... 6

6 Female: Dorsal striae transverse, or mostly so, between setae e1–e1, forming an “hourglass” shape between setae fl- f1 (6a)... canadensis species group.............................................................................. 7

- Female: Dorsal striae longitudinal between setae e1–e1, forming a diamond shape between setae e1–f1 (6b)............ 9

7 Female: Pregenital striae entire, strong, sometimes with lobes; striae between e1–e1 often irregular, wavy (7a). Male: Knob of aedeagus with flattened dorsal surface (7c); empodia I–II with spurs minute or absent, ≤ 1 µm long (7f)................................................................................................. T. lambi Pritchard & Baker

- Female: Pregenital striae broken, always without lobes; striae between e1–e1 mostly or entirely straight, transverse (7b). Male: Knob of aedeagus with convex dorsal surface (7d, 7e); empodia I–II with large spurs,> 2 µm (7g)............... 8

8 Female: Pregenital striae fine, including several incomplete longitudinal lines (8a)............ T. canadensis (McGregor)

- Female: Pregenital striae coarse, comprising strong longitudinal lines (8b)...................... T. schoenei McGregor

9 Female: Empodium of tarsus I with unusually long (> 20 µm) spur (9a). Male: Length of knob of aedeagus> 2x the width of the neck 9c).............................................................. T. bunda Flechtmann & Knihinicki

- Female: Empodium of tarsus I with small (<5 µm) spur (9b). Male: Length of knob of aedeagus variable, but knob of aedeagus usually <2x width of the neck (e.g., 9d).............................................................. 10

10* 2 Females: Tarsus I with the socket of proximal duplex setae overlapping with the sockets of 2–5 (usually 3 or 4) proximal tactile setae (10a,b): ∑d prox <10 µm* 2 ...................................................................... 11

- Females: Tarsus I with the socket of proximal duplex setae distal to the sockets of 4 proximal tactile setae (10c), although some specimens may have 1–2 setae overlapping: ∑d prox> 10 µm* 2 ............................................ 15

11 Female: Tarsus I with the sockets of 1–2 tactile setae proximal to the socket of the proximal pair of duplex setae (11a,b): ∑d prox 2–10 µm. Lobes present on ventral striae. Male: Posterior projection of aedeagus present but small (11d).............. 12

- Female: Tarsus I with the sockets of zero tactile setae proximal to the socket of proximal pair of duplex setae (11c). Lobes present or absent on ventral striae. Male: Posterior projection of aedeagus absent OR large and directed dorsally or bent sharply downwards (11e)..................... desertorum species group................................... 13 12* 3 Female: On tarsus I, socket of l ' just proximal to the proximal duplex setae (ca. 2 µm), the other 3 proximal tactile setae clearly overlapping with duplex setae (see 11b). Lobes on ventral striae between genital area and setae 1a. Male: All empodia with large (4 µm) dorsal spurs (12a)................................................ T. macfarlanei Baker & Pritchard

- Female: On tarsus I, socket of l ' 5–7 µm from the proximal edge of the proximal duplex setae, the sockets of the other 3 proximal tactile setae overlapping or slightly proximal to the proximal duplex setae (see 11a). Lobes on ventral striae only between genital region and setae 4a. Male: All empodia with small (2 µm) spurs or spurs absent (12b)........... T. yusti McGregor

13 Female: Pregenital striae broken anteromedially (13a). Lobes present on ventral striae extending from genital area to at least setae 2a. Male: Empodia II with long, thin proximoventral hairs, unlike empodia I, similar to empodia III–IV (13c). Aedeagus with knob directed dorsally, short anterior projection, posterior margin smoothly curved with medial ridge that can appear like a hook (13e)............................................................................. T. ludeni Zacher

- Female: Pregenital striae entire (13b), but may be sparse medially with small breaks. Lobes absent on ventral striae. Male: Empodia II claw-like, like empodia I, different from empodia III–IV (13d). Posterior projection of aedeagus present (13f) 14

14 Male: Knob of aedeagus with axis parallel or at slight angle to that of the main shaft; posterior projection of aedeagus a large sharp hook, bent downwards (14a). Female: Pregenital striae entire and dense laterally and medially.. T. desertorum Banks

- Male: Knob of aedeagus directed at dorsal angle to axis of shaft (14b). Female: Pregenital striae entire, sometimes sparse and slightly broken medially.......................................................... T. evansi Baker & Pritchard

15 Female: Empodia I–II with a large (≥ 4 µm long) spur (15a)................................................. 16

- Female: Empodia I–II with spur absent or small (≤ 2 µm long) (15b, 15c)....................................... 17 16* 4 Female: Lobes entirely, or almost entirely, absent on dorsal and ventral striae (16a). Rarely found on host plants other than Ulex spp. (Fabaceae) ................................................................... T. lintearius Dufour

- Female: Lobes present on dorsal and ventral striae (16b)......................................... T. gloveri Banks 17 Female: Peritreme with hook 10–15 µm long. Found only on Dianella spp. (Phormiaceae) ............. T. dianellae Davis

- Female: Peritreme with hook> 15 µm long, usually> 20 µm (17a)............................................ 18 18 Male: Knob of aedeagus at a conspicuous angle (30–45 º) to the main shaft of aedeagus (18a) OR knob indistinct or absent (18b)............................................................................................. 19

- Male: Knob of aedeagus small to large, but distinct, parallel to shaft of aedeagus, or nearly so, forming an angle of 0–20 º (18c,d,e)........................................................................................... 20 19 Male: Aedeagus with a distinct knob, the posterior projection long (19a)........................ T. marianae McGregor

- Male: Aedeagus without a distinct knob, weakly sigmoid, with neck tapering to a pointed tip (19b).... T. piercei McGregor 20 Male : Empodia I –II with spurs minute or absent, ≤ 1 µm long (20a)........................................... 21

- Male: Empodial I–II with larger spurs, ≥ 2 µm long (2b).................................................... 22 21* 1 Males: Dorsal margin of knob of aedeagus highly rounded, with medial indentation (21a)....... T. neocaledonicus (Andre) - Males: Dorsal margin of knob of aedeagus slightly rounded, without medial indentation (21b).. T. lombardinii Baker & Pritchard

22 Male: Dorsal margin of knob of aedeagus with a medial indentation (23a)......................... T. truncatus Ehara - Male: Dorsal margin of knob of aedeagus angulate flat or evenly rounded (23b, 23c, 23d).......................... 23

23 Male: Knob of aedeagus with large posterior projection, its length approximately equal to the width of the neck; dorsal margin of the knob angulate (23b).................................................. T. turkestani (Ugarov & Nikolskii)

- Male: Knob of aedeagus with smaller posterior projection, its length shorter than the width of the neck; dorsal margin of the knob rounded or angulate (23c, 23d).................................................................... 24

24 Male: Knob of aedeagus large, about twice as wide as the width of the neck; dorsal margin of knob tends to be rounded (23c). Female: Females collected in summer are red............................................... T. kanzawai Kishida

- Male: Knob of aedeagus small, less than twice as long (about 1.5x) as the width of the neck; dorsal margin of knob tends to be angulate (23d). Female: Females collected in summer are green, yellow or red......................... T. urticae Koch

Figures

FIGURE 9. Lateral view of the aedeagus of Tetranychus spp., with posterior projections to the right hand side.