Cillaeopeplus

Sharp 1908 

C. staphyliniformis	C. dubius

Cilck on image for larger view

Cillaeopeplus is a relatively homogeneous and externally primitive group of 11 species, all of which are single island endemics. All species are elongate, parallel sided, and moderately to extremely flattened.

The genus Notopeplus was described for a single widespread species collected on Koa, banana, and Loulu palms (Pritchardia spp.), Cillaeopeplus (Notopeplus) reitteri. It differs from the species placed in Cillaeopeplus in being larger and proportionally less flattened. External and genitalic characters support a close relationship with Cillaeopelus, described for species found on Kauai, Oahu, and Lanai. The current hypothesis of relationship, based on 52 morphological characters (primarily male genitalic), places Notopeplus as sister to the remaining 10 Cillaeopeplus species.

There are four lineages of Cillaeopeplus, all of which are present on Kauai. Morphology supports Notopeplus reitteri as sister to the nine Cillaeopeplus species.

The other three lineages are more similar to each other, being smaller and more depressed (flatter, not sadder). Each lineage is closely associated with a different host plant genus, with only one species from Oahu being rarely found on alternate hosts.

• Pisonia spp. (Nyctaginaceae) associated: One species endemic to Kauai, two endemic to Oahu. Lanai Cillaeopeplus, host plant association unknown, but related to Pisonia associated species.
   
• Charpentiera spp. (Amaranthaceae) associated: Two endemic species on Kauai, one endemic species on Oahu.
   
• Pleomele spp. (Agavaceae) associated: Kauai and Oahu each supports one endemic species.

These three genera are unusual in that they are pseudo-woody. Trunks and branches of woody trees are solid, while these trees have trunks composed of fiberous concentric rings with very narrow spaces between. The flattened and parallel sided body form of Cillaeopeplus species is well suited to moving between the rings of the decaying trunks where they feed. The two species pictured above were collected from the same Pisonia trunk near Puu Kaua on Oahu.