Probably a moderate Neotropical genus. Several species, sometimes cryptic, have been found and will be described .
Moderate size, body length 2.9–4.2 mm. Occipital carina present and complete, joining hypostomal carina before mandible. Malar suture absent. Maxillary palpi 6-segmented, labial palpi 4-segmented. Scape of antenna without apical lobe or basal constriction. Mesoscutum strongly declivous anteriorly. Mesoscutal lobes mostly coriaceous, occasionally with smooth areas. Notauli deep, wide and scrobiculate, not joining, reaching the end of mesoscutum. Subalar sulcus wide, joining mesopleural sulcus. Mesopleural sulcus narrow. Precoxal sulcus wide, deep and scrobiculate. Propodeum mostly coriaceous, with a median longitudinal and two sublateral longitudinal carinae. Propodeal areola present and well defined. Apicolateral propodeal spines and propodeal spines over hind coxa indistinct. Pterostigma of fore wing wide. Vein m-cu often arising basally to vein 2RS, thus vein (RS + M)b present. First subdiscal cell open at apex. Vein r-m present. Hind wing M+CU ~0.25 length of vein 1M. Vein m-cu of hind wing slightly curved distally. Fore tibia with an irregular row of at least seven spines. Hind coxa without basoventral tubercle. Basal sternal plate of first metasomal segment 0.53–0.72 length of tergum. First metasomal median tergite costate with coriaceous microsculpture; second median tergite at least partially sculptured; third and remaining median tergites smooth and polished. Ovipositor apex strongly sclerotised, with a single nodus .
Bolivar is morphologically similar to Spathius and Notiospathius, with these three genera sharing a first metasomal tergum with a considerably elongated, petiolate basal sternal plate (0.5 times the length of tergum). The new genus can be distinguished from both Spathius and Notiospathius by having the vein m-cu of hind wing slightly curved distally (always straight in the latter two genera). Moreover, species of Bolivar differ from those of Spathius by having the first subdiscal cell of fore wing open at apex (closed in Spathius), vein m-cu of fore wing arising basally to vein 2RS, thus vein (RS + M)b present (m-cu arising distally, (RS + M)b absent in Spathius), and basoventral tooth of hind coxa absent (present in Spathius). Species of Bolivar differ from those of Notiospathius by having the mesoscutal lobes mostly coriaceous (variable but often with striate and/or rugose areas in Notiospathius), a distinct propodeal areola (absent in Notiospathius), and notauli not joining, reaching the end of mesoscutum (notauli obscuring in a rugose and/or longitudinally costate area, often not reaching the end of mesoscutum in Notiospathius) .
The species of Bolivar appeared grouped within the South American major clade comprising four genera, with Semirhytus as their sister taxon, followed below by Johnsonius Marsh and Parallorhogas Marsh, in that order. Members of Notiospathius and Spathius, to which species of Bolivar are morphologically similar, were, however, recovered in distantly related clades, thus confirming the validity of the new genus .