Discochiton

Chris J. Hodgson & Douglas J. Williams, 2018, Revision of the soft scale genus Paralecanium (Hemiptera: Coccomorpha: Coccidae) with the introduction of three new genera and twenty new species, Zootaxa 4443 (1), pp. 1-162 : 16-18

Key to species of Discochiton based on adult female morphology

1. Legs present and well developed, each with 5 distinct segments................................................ 2 - Legs absent or represented by small leg stubs, each with 1 (rarely 2 or 3, D. paucipedis ) segments...................... 3

2. Preopercular pores restricted to around CA4. Antenna well developed, with 6 distinct segments and hair-like setae present on segments IV and V. A few long setae present ventrally, laterad to each side of anterior end of anal cleft)................................................................................................... D. luzonicum (Cockerell)

- Preopercular pores associated with both CA3 and CA4. Antennal segmentation indistinct between apical 3 segments, and hairlike setae absent from segments IV and V. Setae laterad to each side of anterior end of anal cleft either short or absent......................................................................................... D. trifasciatum (Green)

3. Marginal setae spinose, not fan-shaped................................................ D. pseudexpansum (Green)

- Marginal setae fan-shaped............................................................................... 4

4. All stigmatic clefts usually with 5 (rarely 4) stigmatic spines. Dorsal setae of one size, each 16–18 µm long, straight, more or less parallel-sided and sharply pointed. Spiracular disc-pore bands broad.................... D. martini Hodgson spec. n.

- All stigmatic clefts usually with 3 stigmatic spines (except some D. expansum and D. seychellarum ). Other characters not in this combination..................................................................................... 5

5. Legs present, either as one-segmented leg stubs or rarely with up to 3 segments.................................... 6

- Legs entirely absent.................................................................................. 11

6. Legs showing some segmentation, with coxae and 1 or 2 further segments, each leg more than 50 µm long............... 7

- All legs represented just by one-segmented leg stubs, total length less than 25 µm................................. 8

7. Dorsal setae parallel-sided or slightly capitate. Spiracular disc-pore band narrow, only 1 or 2 pores wide. Margins of each stigmatic cleft not heavily sclerotised. Preopercular pores often present associated with all 4 abdominal clear areas....................................................................................... D. paucipedis Hodgson , spec. n.

- Dorsal setae sharply pointed. Spiracular disc-pore band broad, 3+ pores wide. Margins of each stigmatic cleft heavily sclerotised. Preopercular pores absent from anterior 2 abdominal clear areas (CA1 and CA2).... D. crenulatum Hodgson spec. n.

8. Preopercular pores absent from CA1 (anterior abdominal clear area), often absent from CA2 and most abundant around CA4. Dorsal setae parallel-sided and frequently slightly capitate.................................... D. expansum (Green)

- Preopercular pores always associated with all of CA1–CA4 (anterior 4 abdominal clear areas). Dorsal setae setose and sharply pointed.............................................................................................. 9

9. Dorsum with 2 sizes of dorsal setae*: those in submargin short, those in each submedial band much longer, each seta up to 85 µm long. Stigmatic spines short, subequal in length and parallel-sided.......................... D. vacuum (Morrison)

- Dorsum with only 1 size of dorsal setae, none more than 20 µm long. Stigmatic spines not as above.................. 10

10. Stigmatic spines short and bullet-shaped, broad basally and narrowing to a sharp apex. Dorsal setae long, each up to 17 µm long. Marginal setae almost round....................................................... D. javanicum (Green)

- Stigmatic spines not bullet-shaped, each parallel-sided with a blunt apex. Dorsal setae short, each up to 10 µm long. Marginal setae broadly oval............................................................... D. browni Hodgson spec. n.

11. Dorsum with numerous small papillate dermal structures. Preopercular pores restricted to CA3 and CA4............................................................................................ D. papillatum Hodgson spec. n.

- Dorsum without small papillate dermal structures. Preopercular pores in various arrangements....................... 12

12. Preopercular pores present associated with CA3 and/or CA4 only............................................. 13

- Preopercular pores present associated with at least 3 pairs of abdominal clear areas (if 2 clear areas only, then absent from CA4).............................................................................................. 14

13. Preopercular pores present in a tight group slightly removed from and not surrounding each CA4. Ventral marginal band without pale areolations................................................................ D. malainum (Takahashi)

- Preopercular pores present in loose groups around CA3 and CA4. Ventral marginal band with pale areolations...................................................................................... D. sarawakense Hodgson spec. n.

14. Preopercular pores present associated with all 4 anterior abdominal clear areas.................................... 15

- Preopercular pores present associated with only 3 or fewer pairs of abdominal clear areas........................... 18

15. Long pregenital setae absent. Each anal plate with outer margin near apex rather serrate and often with setae on posterior margin stouter than other setae on posterior margin of each plate. Stigmatic spines short and narrow, less than 30 µm long. Lateral margins of each stigmatic cleft poorly sclerotised.......................................... D. cocophyllae (Banks)

- Long pregenital setae present. Each anal plate with outer margin near apex not serrate and with all anal plate setae small and setose. Stigmatic spines long and narrow, median setae more than 40 µm long. Lateral margins of each stigmatic cleft well sclerotised......................................................................................... 16

16. Dorsal setae short, each 6–7 µm long, parallel-sided and blunt. Preopercular pores associated with CA1 few, those occurring further posteriorly much more abundant. Venter laterad to anterior end of anal cleft with a group of long setae. each stigmatic cleft with sclerotisation along entire length of lateral margins. Each anal plate rather crumpled near apex............................................................................................ D. diplodiscus Hodgson spec. n.

- Dorsal setae mostly significantly longer, each more than 10 µm long, either parallel-sided or more pointed. Preopercular pores either few, generally less than 10 associated with each abdominal clear area, or about equally frequent in each group. Venter laterad to anterior end of anal cleft with or without a group of long setae. Each stigmatic cleft not as above............. 17

17. Dorsal setae sharply pointed, each less than 20 µm long. Most clear areas each with more than 10 preopercular pores. Stigmatic clefts often each with more than 3 stigmatic spines...................... D. seychellarum Williams & Hodgson spec. n.

- Dorsal setae parallel-sided with apex blunt or capitate, each more than 20 µm long. Most clear areas each with fewer than 10 preopercular pores. Stigmatic clefts each with only 3 stigmatic spines............................. D. mancum (Green)

18. Dorsal setae short, curved and sharply pointed, present throughout most of dorsum. Preopercular pores in very loose groups around and between each abdominal clear area............................................. D. milleri (Takahashi)

- Dorsal setae not as above. Preopercular pores in quite tight groups around each abdominal clear area but not present between them............................................................................................... 19

19. Dorsal setae tapering to a blunt point, not obviously capitate. Preopercular pores associated with CA1–CA3 inclusive..... 20

- Dorsal setae with parallel sides and usually obviously capitate. Preopercular pores associated with CA2 and CA3 only (if present associated with CA1, these very few)................................................... D. rotundum (Green)

20. Dorsum of mature adult with a very characteristic polygonal pattern of sclerotisation and small dermal spots. Stigmatic spines short, each 30–38 µm long. Anal plates each more than 300 µm long............................ D. metallicum (Green)

- Dorsum of mature adult rather uniformly sclerotised. Stigmatic spines longer, each 45–60 µm long. Anal plates each less than 200 µm long......................................................................... D. quadratum (Green)

*Note. The larger dorsal setae are probably easily broken off during mounting and are mostly represented by their basal sockets on many specimens. Careful searching will usually locate one or more complete seta.