Male, pinned, with genitalia in a separate microvial. Original labels: “PANAMÁ, Cerro Campana, 3000’. July 29 1970, H. and A. Howden” (USNMNH).

Costa Rica • 1♂; Limón, Res. Biol. Hitoy Cerere; 100 m; 6–16 May 1992; G. Carballo leg.; L-N 184200_643300 (MNCR). 1♂; Limón, Valle de la Estrella, R. B. Hitoy Cerere; 100 m; 04 Mar. 1994; G. Carballo leg.; L-N 643400_184600, #2889” (MNCR). Panamá • 1♂; same data as the holotype; 31 July 1970 (USNMNH). 1♂; Pr. Cerro Campana; 8°40'N, 79°56'W, 850 m; 14 July 1971; H. A. Hespenheide leg. (USNMNH). 1♂, same data, 10 Feb. 1973; W. Bivin leg. (USNMNH).

Dorsal color black or dark brown; pronotum almost completely yellow; each elytron with three or four yellow spots. Male abdomen with a setal tuft on the first ventrite and several ventrites emarginated and depressed.

Holotype. Male. Length 3 mm, width 2.2 mm, body oval, dorsally convex. Dorsal color black except head pale yellow; pronotum pale yellow with only a basal black macula; each elytron with four yellow spots in humeral, discal, mid-lateral and sub-apical positions (Fig. 7). Ventral surface with head, prosternum, metaventrite and abdomen dark brown; legs, mouthparts and antennae yellow. Head punctures small, separated by their diameter, each puncture as large as an eye facet; pronotal punctures larger than head punctures, separated by their diameter; elytral punctures as large as pronotum punctures, separated by their diameter; metaventral punctures as large as elytral punctures, separated by their diameter. Clypeus emarginate. Carinae on prosternal process straight, convergent, joined near the anterior prosternal border, larger than half prosternum. Protibia not flanged, basal tooth small. Basal abdominal ventrite with setal tuft at center. Abdomen with postcoxal line on basal abdominal ventrite slightly flattened along posterior ventrite margin, ventrite with sparse, long pubescence and small, dense punctures. Ventrites II-VI depressed and emarginated, punctures fine, dense. Genitalia with penis guide as long as parameres, symmetrical, slender, sides slightly pinched at basal half, widened in the apical third, apex acute (Fig. 53); parameres slender, basally wide, narrowed to apex, apex rounded, setae rising from the convex side margin and apex (Fig. 52); penis robust, strongly curved in basal half, widened in apical third with a narrowing before apex, alae short and slender, basal capsule without crest, inner arm long, parallel sided, rounded at apex (Figs 54, 55).

Female. Unknown.

Unknown.

The name refers to the Panamá isthmus.

PANAMÁ, Panamá Oeste: Parque Nacional Altos de Campana, Cerro de la Campana, 8°42'49.4"N, 79°57'10.24"W.

Costa Rica and Panamá.

The coloration of the species is similar to that of the dentipes group of species, but B. isthmena lacks the ventral cusps of the male, instead it shows a setal tuft on the first ventrite.