Cissidium

Darby, Michael, 2020, A revision of Cissidium Motschulsky (Coleoptera: Ptiliidae) with seventy seven new species, European Journal of Taxonomy 622, pp. 1-188 : 137-138

Key to species group 4B

1. Mesoventral lateral margins serrate................................................................................................... 2 – Mesoventral lateral margins without serrations................................................................................. 6

2. Pronotum lateral margins angulate .................................................................................................... 3 – Pronotum lateral margins rounded..................................................................................................... 4

3. Pronotum lateral margins less strongly angled, almost parallel-sided before hind angles, wider than the elytral base ......................................................................................... C. cryptophagoides sp. nov. – Pronotal base narrower with two linear depressions, sides strongly angled ....................................... .................................................................................................................... C. shibatai Sawada, 2008

4. Elytra narrow, pronotum lateral margins almost parallel-sided base without linear depressions........ ........................................................................................................................ C. sakaii Sawada, 2008 – Elytra rounded ................................................................................................................................... 5

5. Mid-keel wider anteriorly ...................................................................... C. nishikawai Sawada, 2008 – Mid-keel wider posteriorly .................................................................... C. elongatum Sawada, 2008

6. Mesoventral lateral margins partly or completely effaced .............................................................. 15 – Mesoventral lateral margins distinct to mesocoxal borders............................................................... 7

7. Mesoventral collar without a median extension ................................................ C. obsoletum sp. nov. – Mesoventral collar with a median extension ..................................................................................... 8

8. Mesoventrite lateral margins with a distinct concave bulge at the posterior angle ........................... 9 – Mesoventral lateral margins without a concave bulge..................................................................... 14

9. Mid-keel not fusing with the posterior border of the mesoventral collar the anterior angles not interrupting the line of the posterior margin................................................................................... 10 – Mid keel fusing with the posterior border of the mesoventral collar ...............................................11

10. Raised posterior margin before keel broad and strongly sculpted..................... C. ibicarense sp. nov. – Raised posterior margin before keel narrower not sculpted ............................. C. peruviense sp. nov.

11. Larger species ± 0.90 mm ......................................................................................... C. orami sp. nov. – Smaller species ± 0.65–0.70 mm ..................................................................................................... 12

12 Mesoventral lateral margin hind angle sharp the concave extrusion very small................................. ................................................................................................................................. C. dybasi sp. nov. – Mesoventral lateral margin hind angle more rounded..................................................................... 13

13. Mid-keel broad, short, mesoventral collar extension short .................... C. reitteri ( Matthews, 1889) – Mid keel narrower, longer, mesoventral collar extension longer ....................... C. bomjesus sp. nov.

14. Mid-keel very much reduced almost absent, keel strongly sculpted ................... C. losbanos sp. nov. – Keel narrow before joining keel, less strongly sculpted................................ C. sawadai Darby, 2015

15. Keel very broad, flat, with rounded tip .............................................................. C. similatum sp. nov. – Keel narrower .................................................................................................................................. 16 16. Mid-keel sides strongly widened anteriorly .................................................................................... 17 – Mid-keel sides not so widened anteriorly, sides concave ................................................................ 19

17. Posterior margins of humeri very long ............................................................................................ 18 – Posterior margins of humeri shorter, mid-keel with concave sides .................................................... ............................................................................................................... C. basale Motschulsky, 1855

18. Longer species, mid-keel wider........................................................................... C. lisae Darby, 2015 – Shorter species, mid keel shorter, keel much narrower ................................... C. tigrum Darby, 2015

19. Mid-keel hind angles rounded ........................................................................... C. obscenum sp. nov. – Mid-keel hind angles not rounded, extending towards mesocoxal posterior border....................... 20

20. Mesoventral collar without a medial extension .................................................. C. dividuum sp. nov. – Mesoventral collar with a medial extension .................................................................................... 21

21. Mesoventral median extension long, with a splayed end, keel very long and narrow ........................................................................................................ C. subangulatum sp. nov. – Shorter species, mid-keel shorter, keel shorter and wider at base ................... C. angulatum sp. nov.