Cissidium Motschulsky 1855
Creators: name: Darby, Michael
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Ptiliidae
Cissidium

description: Key to Cissidium species in group 4A
1. Species with longitudinal linear depressions on the pronotum ......................................................... 2
– Species without linear depressions on the pronotum......................................................................... 4
2. Linear depressions very faint (best seen with side lighting).................................. C. trangse sp. nov.
– Linear depressions well marked ........................................................................................................ 3
3. Linear depressions long almost reaching mid-point of pronotum, pronotum more densely pubescent .......................................................................................................... C. bilineatum sp. nov.
– Linear depressions shorter, pronotum more sparsely pubescent ....................... C. arcuatum sp. nov.
4. Mentum triangular ................................................................................... C. triangulum Darby, 2019
– Mentum not triangular ....................................................................................................................... 5
5. Head small, pronotum domed, sides almost parallel before hind angles, base of pronotum wider than elytra ................................................................................................................................................. 6
– Pronotum not so domed, not wider than elytra, head larger in proportion ........................................ 7
6. Pronotal hind angles acute, projected rearwards .............................................. C. seditiosum sp. nov.
– Pronotal hind angles rounded, not projected rearward ......................................... C. insulare sp. nov.
7. Pronotum cordate, posterior margin same width as distance across the eyes, elytra almost parallelsided, very small species..................................................................................... C. besucheti sp. nov.
– Larger species, pronotal posterior margin clearly wider than distance across eyes .......................... 8
8. Posterior margins of pronotum almost parallel-sided ....................................................................... 9
– Posterior margins of pronotum clearly concave before hind angles................................................ 10
9. Mesoventral lateral margins serrate.......................................................................... C. loebli sp. nov.
– Mesoventral lateral margins without serrations.......................................... C. globosum Darby, 2015
10. Mid-keel rounded/tapering posteriorly, without projecting hind angles...........................................11
– Mid-keel with clearly projecting posterior angles........................................................................... 14
11. Mid-keel very narrow parallel-sided then tapering to keel.............................................................. 12
– Mid-keel wider, posterior angles rounded ....................................................................................... 13
12. Mid-keel tapering to keel from end of the very narrow medial process of the collar ......................... ............................................................................................................................ C. visendum sp. nov.
– Mid-keel parallel-sided for most of its length before tapering to join keel ......................................... ........................................................................................................................ C. plaumanni sp. nov.
13. Mesoventral collar with two short posteriorly directed processes either side of the medial process .................................................................................................................. C. opacum sp. nov.
– Collar without processes either side of the medial process ....................................... C. steeli sp. nov.
14. Mesoventral lateral borders effaced in posterior half ..................................................................... 15.
– Mesoventral lateral borders distinct to mesocoxae......................................................................... 16.
15. Pronotum widest in basal half, pubescence sparser.......................................... C. luctuosum sp. nov.
– Pronotum widest medially pubescence denser .................................................... C. faustum sp. nov.
16. Sides of mid-keel straight to posterior angles.................................................... C. obscurum sp. nov.
– Sides of mid-keel not straight concave or slightly convex .............................................................. 17
17. Sides of mid keel slightly concave same width as the median extension of the collar anteriorly and strongly widening posteriorly ................................................................. C. elongatum Sawada, 2008
– Mid-keel sides concave.................................................................................................................... 18
18. Mid keel sides more pronouncedly concave, narrower at termination of the medial extension of the collar, chaetotaxy of male abdominal ventrites distinctive.................................. C. petri Darby, 2015
– Mid keel sides less pronouncedly concave wider at termination of the medial extension of the collar ................................................................................................................................................ 19
19. Posterior border of pronotum well-marked to emargination opposite the scutellum ...................... 20
– Posterior border of pronotum very short reaching only half way to emargination opposite the scutellum.................................................................................................................. C. eciton sp. nov.
20. Tip of keel sharply pointed .............................................................................................................. 21
– Tip of keel blunt/rounded................................................................................................................. 22
21. Pronotal posterior border very narrow...................................................................... C. sueae sp. nov.
– Pronotal posterior border wider, clearly distinct............................................. C. subfaustum sp. nov.
22. Medial extension of collar tapering to a blunt point............................................... C. flavum sp. nov.
– Medial extension of collar parallel-sided ........................................................................................ 23
23. Pronotum wider, lateral margins more sharply rounded............................... C. ecuadoriense sp. nov.
– Pronotum narrower, sides more smoothly rounded ................................................ C. angusi sp. nov.
description: Published as part of Darby, Michael, 2020, A revision of Cissidium Motschulsky (Coleoptera: Ptiliidae) with seventy seven new species, pp. 1-188 in European Journal of Taxonomy 622 on pages 98-100, DOI: 10.5852/ejt.2020.622, http://zenodo.org/record/3777282