Key to families in the “ Xylococcidae and related groups” based on macropterous adult male

Notes: the following key is mainly based on the key in Hodgson & Foldi (2006) for the extant families and on the key in Koteja (2008) for the extinct families. The Kuwaniidae information is from the description for Kuwania bipora (Wu 2008) .

1(0) Groups of tubular ducts present medially on abdominal segments VII only........................................ 2

- Groups of tubular ducts present medially on both segments VI and VII.......................................... 3

2(1) Antennae 10-segmented; fore wing with regular pinnate sculpture.................................. Matsucoccidae

- Antennae 9-segmented; fore wing without regular pinnate sculpture.................................... Ortheziidae

3(1) Fore wing with a club-shaped pterostigma................................................................. 4

- Fore wing without pterostigma.......................................................................... 7

4(3) Fore legs fossorial......................................................................... Margarodidae

- Fore legs normally developed, not fossorial................................................................ 5

5(4) Fore wing with anterior flexing patch forked, and 2 posterior flexing patches............................ Qinococcidae

- Fore wing with anterior flexing patch unbranched, and 0 or 1 posterior flexing patch............................... 6

6(5) Fore wing with cubital ridge and posterior flexing patch............................................ Weitschatidae

- Fore wing without cubital ridge or posterior flexing patch........................................... Jersicoccidae

7(3) Antennae pectinate....................................................................... Stigmacoccidae

- Antennae filiform..................................................................................... 8

8(7) Each claw with several digitules.............................................................. Callipappidae

- Each claw with 1 pair of digitules........................................................................ 9

9(8) Tarsus 5-segmented........................................................................ Macrodrilidae

- Tarsus with 1 or 2 segments............................................................................ 10

10(9) Fore wing with radial sector vein........................................................................ 11

- Fore wing without radial sector vein..................................................................... 12

11(10) Endophallus present; claw with a pair of acute digitules............................................ Xylococcidae

- Endophallus absent; claw with a pair of knobbed digitules........................................... Kuwaniidae

12(10) Capitate setae present on antennae and legs........................................................ Arnoldidae

- Capitate setae absent................................................................................. 13

13(12) Cubital ridge long, approaching posterior wing margin beyond 2/3 of its length; scutellum triangular........... Grohnidae

- Cubital ridge very short, reaching posterior wing margin at 1/4 of its length; scutellum oval................. Serafinidae