Cissidium, Motschulsky, 1855, Motschulsky, 1855

Darby, Michael, 2020, A revision of Cissidium Motschulsky (Coleoptera: Ptiliidae) with seventy seven new species, European Journal of Taxonomy 622, pp. 1-188 : 72-73

Key to species in species group 3

1. Pronotum with two linear depressions composed of united foveolae (note: C. longum Darby, 2019 shows traces on one side of the pronotum of a short depression but is not treated in this section of the key, see below)............................................................................................................................. 2

– Pronotum without linear depressions................................................................................................. 6

2. Posterior corners of mid-keel rounded ( Fig. 48C ).............................................. C. dewhurst sp. nov. – Posterior corners of mid-keel with projecting angles ........................................................................ 3

3. Lateral margins of pronotum rounded ............................................................................................... 4 – Lateral margins of pronotum angulate............................................................................................... 5

4. Larger more rounded species...................................................................... C. globulum Darby, 2019 – Smaller, narrower species .................................................................................... C. murphyi sp. nov.

5. Mesoventral mid-keel elongate ( Fig. 56C ) ........................................................ C. mindanao sp. nov. – Mesoventral mid-keel square ( Fig. 55C ) .................................................. C. marshallae Darby, 2019

6. Pronotal disc with only a trace of foveolae .................................................. C. amazonicum sp. nov. – Pronotal foveolae covering the disc................................................................................................... 7 7. Lateral margins of pronotum angular ................................................................................................ 8 – Lateral margins of pronotum rounded ............................................................................................. 10

8. Mesoventral lateral margins rectangular, hind angles acute.......................... C. longum Darby, 2019 – Mesoventral lateral margins not rectangular .................................................................................... 9

9. Mid-keel very narrow at junction with collar......................................... C. amboroense Darby, 2015 – Mid-keel wide at junction with collar.............................................................. C. puncticolle sp. nov.

10. Elytra almost parallel-sided in posterior half....................................................................................11 – Elytra sinuate in posterior half ........................................................................................................ 12

11. Pronotum densely and finely foveolate ( Fig. 54B ) ................................................ C. mahleri sp. nov. – Pronotum sparsely and more coarsely foveolate ................................................... C. werneri sp. nov.

12. Mid-keel not joining collar anteriorly.............................................................................................. 13 – Mid-keel joining collar .................................................................................................................... 14

13. Smaller species length 0.6–0.7 mm, elytra shorter in proportion to pronotum .. C. itoi Sawada, 2008 – Larger species length 0.8 mm, elytra longer in proportion to pronotum ........ C. latum Sawada, 2008

14. Mid-keel almost parallel-sided, hind angles rounded....................................... C. pilosellum sp. nov. – Mid-keel not parallel-sided.............................................................................................................. 15

15. Mid keel tapering from wide base by collar to keel.................................. C. nomurai Sawada, 2008 – Mid keel otherwise ............................................................................................................................. 16

16. Mid keel with projecting hind angles ........................................................ C. pauxillum Darby, 2019 – Mid keel reduced to small fragments either side of medial extension of the collar ........................................................................................................... C. ikeuchii Sawada, 2008

Figures

Fig. 48. Cissidium dewhurst sp. nov. A. Habitus. B. Pronotum, × 530. C. Mesoventrite showing median process of collar, mid-keel, keel and lateral margin, × 565.

Fig. 56. Cissidium mindanao sp. nov. A. Habitus. B. Pronotum, × 430. C. Mesoventrite showing median process of collar, mid-keel, keel and lateral margin, × 660.

Fig. 55. Cissidium marshallae Darby, 2019. A. Habitus. B. Pronotum, × 640. C. Mesoventrite showing median process of collar, mid-keel, keel and lateral margin, × 750.

Fig. 54. Cissidium mahleri sp. nov. A. Habitus. B. Pronotum, × 630. C. Mesoventrite showing median process of collar, mid-keel and keel, × 545.