Diagnostic characters. Hypopygium short, evenly sclerotized; ovipositor sheath short, with hairs near apex. Tergite I short, subrectangular, slightly wider apically, mostly sculptured; tergite II rectangular, wider than long and completely sculptured, the apical suture well defined; tergum III sligthly to much shorter than II. Terga III-VI with a single band of sparse hairs. Propodeum short and strongly declivous, more or less areolated and dull; but never with a median longitudinal carina on the declivous part nor rugose all over. Anterior margin of metanotum far behind margin of scutellum laterally, exposing a wide section of the scutellar phragrna; laterally the metanotum bearing a long cylindrical process with a few apical hairs; the type species, Alloplitis guapo, is exceptional, having metanotum closely appressed to scutellum. Scutellum elevated; the disc with an apical concavity bordered by a carina; margin polished band interrupted medially by sculpture. Mesoscutum usually with strong notauli on posterior half and a weak marginal carina above the tegula. Pronotum with a wide, crenulate median groove and a small ventral groove. Distal flagellomeres of female with special ventral sensory areas; at least some flagellomeres with 2 ranks of placodes; other flagellomeres with placodes scattered or partly organized in 3 or 4 ranks. Hind tibia swollen, the spines on its outer side few and small; tarsal claws with several comb-like teeth; tibial spurs short. Areolet with 3 or 4 sides, the 2nd intercubitus and 2nd Rs about equal. Nervellus sinuate, meeting submediella at a right angle and there producing a short brachiella; vannal lobe with margin nearly straight and hairless (Mason 1981).
The areolated propodeum places this genus rather far from Microplitis. Another distinguishing feature is the strongly apomorphic structure of the metanoturn of two species, A. typhon and A. completus, this structure shared by Philoplitis. Many other similarities leave little doubt that Philoplitis and Alloplitis have a common ancestor despite the striking differences in propodeurn and scutellum (Mason, 1981).
Additional comments by Jose Fernandez-Triana (added on December 2014). The described species of Alloplitis are all found in the Oriental region, but I have seen in collections a few specimens from the Afrotropical region. Although only half dozen species have been described so far, I have seen at least twice that number of additional species (mostly from South East Asia), which will be described in the future. When more study is done, it is reasonable to expect around 20 species of this genus.
Until December 2014, a total of 19 specimens were sampled for DNA, and 16 of them rendered partial or full DNA barcodes. Below is a pdf with a NJ tree (K2P) of all available sequences, and an Excel file with the associate information for those specimens (all deposited in the Canadian National Collection of Insects).