Oncocephala bicristata Chapuis, 1876

Calcetas, Orlando A., Staines, Charles L., Adorada, Jessamyn R., Calilung, Venus J., Caoili, Barbara L. & Jamias, Serlie B., 2021, Review of the Genus Oncocephala Agassiz, 1846 (Coleoptera: Chrysomelidae: Cassidinae: Oncocephalini) in the Philippines, The Coleopterists Bulletin 75 (2), pp. 445-458 : 449-450

Oncocephala bicristata Chapuis, 1876 ( Figs. 6–10 )

Oncocephala bicristata Chapuis 1876 : XXIV. Type locality: Philippines, Luzon ; type depository (two syntypes): RBINS (but see note below).

Redescription (n = 11). Length = 4.8–5.5 mm (apical margin of head to apex of elytron), width = 2.5–2.8 mm (middle of elytra). Head, pronotum and elytra brown with black tinge; legs brown; antennae dark brown ( Fig. 6 ). Head. Compound eyes conical dorsally; dorsal cephalic horn pear-shaped, anterior half distinctly narrower than posterior half in dorsal aspect ( Fig. 7 ), broader towards rounded anterior margin, anvil-shaped in lateral aspect ( Fig. 8 ), rounded anteriorly and posteriorly; with cephalic horn formula of 10 (4-4-2). Antenna. Almost 2× length of pronotum; antennomeres 1 and 2 broader apically; antennomere 3 distinctly longer than 4; antennomeres 4–6 broader apically; antennomeres 7–10 quadrate; antennomere 11 short, conical; antennomere 1 without striation, 2–11 with striation, 2–7 broadly striate, 8–11 finely striate. Antennal length 3.0 mm. Pronotum. Subquadrate; anterior margin almost straight medially; lateral protuberance scalene, distinctly large, with broad basal margin; lateral margin almost straight posterolaterally; anterior angle obtuse, posterior angle acute; posterior margin concave laterally, almost angular medially, broadly carinate; with two conical subapical tubercles; medial longitudinal cavity continuous, uninterrupted; pronotal width 1.5 mm; pronotal length 1.5 mm. Scutellar shield. Anterolateral margin wedge-shaped, lateral margin largely straight, but indented medially, appearing constricted, apically rounded. Elytron. Humeral margin with 2 distinct tubercles, scutellar tubercle minute, humeral tubercle small, almost same height as elytral tubercle 1 of costa II; lateral margin distinctly broader apically with pronounced medial sinuation and small, irregularly spaced teeth; exterior apical angle almost 45°, subconical, pointed apically; apical margin wedge-shaped, minute to indistinctly dentate; sutural angle obtuse; stria 10 short, interrupted by elytral sinuation, stria 11 uninterrupted to sutural margin; with 8 distinct elytral tubercles; costa II with 4 distinct tubercles: T1 small, convex, connect- ed to T2 basally; T2 minute, longitudinal and ridge-like, connected to T3 apically; T3 moderate, convex, connected to T4 basally; T4 longitudinal and ridge-like; T2, T3, and T4 coalesced, with low or narrow elevated margins; costa III with 1 distinct tubercle: T1 small and convex; costa IV with 2 distinct tubercles: T1 and T2 small and conical; costa V without distinct tubercle; elytral tubercle formula 8 (1-4-1- 2-0); elytron width 1.3–1.4 mm; elytron length 3.2–3.8 mm. Leg. Not rugose or tuberculate ( Figs. 6, 9 , 10 ).

Material Examined. Philippines: LUZON: Laguna: Los Banos, Mt. Maquiling , 750 ASL, 12- x-1926 J. A. Tingson (1, SDEI-09776 ) ; Camarines Sur: Calabangan , 26-iv-1931, F. C. Hadden (1, MGFT) ; VIZAYAS: Leyte: Tacloban, W. Schultze (1, SDEI-09723 ) ; MINDANAO: Surigao Del Norte: Siargao , 19-x-1916, S. Dorlutin (1, SDEI-09728 ) ; Surigao, Baker (4, RBINS) ; Bucas Grande, Socorro , 19-x-1916, S. Dorlutin (2, SDEI-09726 , 09727 ) ; Agusan Del Norte: 2 Butuan, Baker (1, RBINS; 1, SDEI-09725 ) .

Distribution. Indonesia (Celebes), Philippines (Leyte, Luzon, Mindanao, Mindoro).

Host Plants. Unknown.

Remarks. The species can be distinguished from all other species of Oncocephala in the Philippines by the exterior apical angles of the elytra being angulate, almost 45°, subconical and pointed apically, while they are triangular and not subconical in O. polilloana . Oncocephala bicristata and O. philippinica can be distinguished from all other species of Oncocephala by tubercle 3 of costa II being convex. The tubercle is also moderate in size in O. bicristata while it is larger in O. philippinica . The lateral protuberance of the pronotum is scalene, distinctly large and with a broad basal margin compared to exterior apical angle of the elytra almost uniformly broad in dorsal view in all eight observed specimens, the posterior margin of the elytra distinctly to slightly sinuate and distinctly or slightly wedge-shaped in dorsal view and elytral tubercle 3 of costa II distinctly to slightly convex laterally. There are also three syntypes of O. bicristata housed in RBINS; however, they were borrowed since 2014 and have not been returned (Limbourgh, personal communication).

Figures

Figs. 6–9. Oncocephala bicristata. 6) Habitus, dorsal aspect; 7) Cephalic horn, dorsal aspect; 8) Cephalic horn, lateral aspect; 9) Habitus, lateral aspect.

Fig. 10. Oncocephala bicristata non-type specimen habitus, dorsal aspect (photograph from MGFT, courtesy of C. Germann and E. Sprecher).