Cillaeopeplus Sharp

Ewing, Curtis, 2007, Phylogenetic analysis of the genera of endemic Hawaiian sap beetles (Coleoptera: Nitidulidae) based on morphology with redescription and key to the genera of endemic Hawaiian Nitidulidae, Zootaxa 1427, pp. 1-36 : 18-19

Cillaeopeplus Sharp

TYPE SPECIES: Brachypeplus infimus Sharp, 1878: 135 (subs. desig., Ford, 1958: 341). Brachypeplus: Sharp, 1878: 131 (syn. in part).

Cillaeopeplus Sharp in Sharp & Scott, 1908: 505 [n. gen., n. spp.].

Notopeplus Sharp in Sharp & Scott, 1908: 505 (n. syn.) [n. gen., n. sp.]. TYPE SPECIES: Notopeplus reitteri Sharp in Sharp & Scott, 1908: 505 (monotypy). Cillaeopeplus: Ford, 1958: 341 [type desig., n. spp., key].

Diagnosis: Most species distinctively depressed, 0.03–0.05 mm thick ( C. reitteri , formerly placed in monotypic genus Notopeplus , 0.7 mm). Size small to medium, 3.5–6.2 mm L, 1.0–1.7 mm W. Sides parallel from pronotum to 6th abdominal segment, terminal abdominal segment broadly rounded at sides (fig. 14). Color pale yellow, dark brown, to nearly black. Microsculpture of dorsum granulate to fine lines, entire surface never glabrous.

Description: Eyes small; temple usually acute, rounded in Cillaeopeplus swezeyi ; antennal grooves weakly convergent; antenna short, club compact, sub quadrate; labrum with small medial tooth, broadly and shallowly emarginate on either side, angles broadly rounded; labium with paraglossae reduced and membranous, small and subquadrate, 3rd segment of palp elongate to subquadrate.

Prothorax quadrate, narrowed anteriorly, or narrowed posteriorly; lateral margins straight to broadly rounded and often serrate; prosternal process wide between coxae, posterad of coxae wide, broadly rounded at apex, and little reflexed dorsad; pleuron with punctures fine and sparse.

Elytra elongate, each more than 2x as long as wide; lateral margin less than 2x width of marginal bead; striae distinct and regular, punctures single and definite to dense and contiguous; interstices of elytra raised with a single series of fine punctures; elytra exposing abdominal segments 7, 6, and part of 5.

Tarsal segments 1–3 with lobes very little dilated.

Abdomen parallel sided. Metacoxal process of 3rd abdominal sternite narrow. Apex of male pygidium truncate to broadly rounded, anal sclerite subtruncate to broadly rounded.

Aedeagus of male with apical margins broadly rounded to sinuate, apex acuminate to acute; sides parallel, slightly wider basally, or expanded subapically; perisac elongate, flagellum usually bifurcated, always extending to distal margin. Female pygidium truncate to broadly rounded; gonocoxites elongate, narrow. Basal ring of spermatheca strongly sclerotized.

Cillaeopeplus comprises six described and five undescribed Hawaiian endemic species from Kauai, Oahu, Lanai, Maui, and Hawaii Island, plus a twelfth species from Guam, Brachypeplus (= Cillaeopeplus ) gracilis Gillogly (1962) . However, examination of the type specimens shows that the latter species does not conform to the generic diagnosis, and the Guam species should be considered incertae sedis in Brachypeplus . The monotypic and rarely collected genus Notopeplus is herein synonymized with Cillaeopeplus .

There are four distinct lineages of Cillaeopeplus , all with representative species endemic to Kauai. Host associations are known for three of the lineages and each is associated with a particular genus of host plant: the Charpentiera , Pisonia , and Pleomele lineages. The host preference for the fourth lineage, C. reitteri , remains obscure, with specimens collected within the concentric rings of banana trees, under bark of Acacia koa , by beating uluhe ferns, and in association with Pritchardia palms. The Pisonia lineage is known from Kauai (2 spp.), Oahu (2 spp.), Lanai (1 sp.), Maui (1 sp.), and the Kilauea area of Hawaii Island (1 sp.). The Charpentiera lineage is found on Kauai (1 sp.), Oahu (1 sp.), and Hawaii Island (1 sp.), also around the Kilauea area. The Pleomele lineage (2 spp.) has been very rarely collected and is known from a single specimen collected on Kauai and two from the northern Koolau Mts. on Oahu. Cillaeopeplus reitteri has been collected on Kauai, Oahu, and the Olaa and Kilauea areas of Hawaii Island. The three species of Cillaeopeplus collected on Hawaii Island are all endemic to Oahu as well, being identical in the form of the male copulatory sac with species from the Waianae Mts. and their presence on Hawaii Island may be the result of human transport of their host plants. The remaining eight species are considered single island endemics. Individuals can be numerous under the right conditions, though their secretive habits and small size has lead to an impression of rarity. All of the species are found in dry to mesic forests and are fully winged. The retention of substantial within-island dispersal ability and fidelity to the ancestral host association has apparently limited speciation.

Cillaeopeplus is similar to Orthostolus ecologically, following the same biogeographic pattern of speciation through colonization from older to younger islands with little within-island differentiation (Ewing 2005).

The placement of Notopeplus as a junior synonym under Cillaeopeplus requires the following new combination.