Amblycerus biacutus Ribeiro-Costa 2025, sp. nov.

Amblycerus biacutus Ribeiro-Costa sp. nov. Fig. 4 A – G, Table 1 Type material. Holotype • Deposited in USNM, male, with labels: Ex Stryphnodendron \ SP. Krukoff \ 800 S – Brazil, AM. \ Manaus, IX / X. 1934 [white label, handwritten in black]; extracted from \ herbarium \ specimen [white label, printed in blue]; Amblycerus prov. nova prox. \ A. sclerolobii \ C. S. Ribeiro-Costa det. 199 .., [white label with black margin, handwritten except name of identifier and date printed in black]; HOLOTYPE \ Amblycerus biacutus \ Ribeiro-Costa [white label with red margin, printed in black]. Diagnosis. This species can be separated from the others by the internal sac of male genitalia with a single, gently curved on both sides and acute at each apex (Fig. 4 F). It can never be confused with A. falcorostrus Ribeiro-Costa & Morse, sp. nov. if comparing this sclerite at AR because of the curvature at apex: in A. biacutus Ribeiro-Costa, sp. nov., it is gently curved; in A. falcorostrus Ribeiro-Costa & Morse, sp. nov. it is strongly curved. Besides, differences can be found in the length at the apex and form of the wishbone-shaped sclerite at RM: in A. biacutus Ribeiro-Costa, sp. nov., it is short and the apex smooth; in A. falcorostrus Ribeiro-Costa & Morse, sp. nov. it is long and the apex serrated (Fig. 3 F). Description. The description of A. biacutus Ribeiro-Costa, sp. nov. is similar to A. truncatus Ribeiro-Costa, sp. nov. except in the following characters. Dimensions: BL: 6.70 mm, BW: 4.00 mm (n = 1). Integument color: Similar to paler specimens of A. truncatus Ribeiro-Costa, sp. nov., except all antennomeres dark brown. Vestiture: Ventral region with whitish pubescence except abdominal ventrites with yellowish pubescence. Head: Frontal carina faint basally. Ocular index 3.94; ocular sinus 0.2 of the eye length in lateral view. Prothorax: Pronotum with carina bordering the basal lobe. Mesothorax and metathorax: Scutellum ~ 1.5 longer than wide with tridentate apex, all teeth the same size. Elytron 2.85 × longer than wide. Metanepisternal sulcus forming right to gentle obtuse angle, vertical axis reaching the margin of metepisternum. Metaventrite with median sulcus extending> 1 / 2 of its length. Hind femur ~ 2.45 × longer than wide. Hind tibia, lateral spur ~ 2 × length of median spur. First tarsomere ~ 1.38 × the length of lateral spur and 2.76 × the length of median spur. Abdomen: Pygidium with truncate apex in male, female unknown. Last ventrite almost the same length as ventrite IV, apex truncate in males, females unknown. Male terminalia. Tergite VIII gently emarginate at apex. Median lobe ~ 4.20 × its widest at apical region; dorsal valve 0.75 × wider than long, lateral margins straight, apex subtruncate; ventral valve 1.18 × wider than long. Armature of internal sac, AR with a single, gently curved sclerite on both sides and, acute at each apex. MR with a pair of winding, laminar sclerites, outer margin serrate along its middle apical 0.5 of length; wishbone-shaped sclerite 0.63 as long as the laminar sclerites length, straight, apex gently curved and smooth in lateral view. Tegmen with lateral lobes cleft to 1 / 11 of their length. Etymology. The specific name, an adjective in the nominative case, is Latin for “ twice acute ”. It refers to the apex of the AR sclerite in the internal sac of male genitalia. Distribution. Brazil (Amazonas-Manaus). Host plant. Fabaceae: Stryphnodendron sp.