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Proceratium HNS Roger, 1863
(Figs 4, 5, 10, 11, 15, 18, 21, 29, 33)
With characters of Proceratiinae HNS . Mandible smaller than in conspecific worker, but also triangular to subtriangular. Frontoclypeal region not projecting dorsally. Frontal carinae separated, not merged into single median carina (Fig. 15). Antennal sockets opening dorsally. Antenna with 13 segments. Labrum bilobed apically (Fig. 29). Second segment of the maxillary palp hammer-shaped (Fig. 33). Pro-, meso-, and metatibia with a single spur. Pygostyles absent.
Forewing in Malagasy species with radial sector between Rs+M and 2r-rs absent, radius and radial sector apical to pterostigma reduced in length, so that the radial sector does not reach the costal margin (Figs 4, 5). On hindwing, cubitus present, free section of the radius present or absent. Radial sector and cu-a crossvein present (Figs 10, 11).
Remarks. Proceratium HNS is the most common genus of Malagasy proceratine males collected by Malaise trap. Proceratium HNS is distinguished easily from the other three Malagasy proceratine genera by the frontal carinae which do not merge into a single carina between antennal sockets (Fig. 15), and by the hindwing with cubitus (Figs 10, 11).
In Malagasy Proceratium HNS , two patterns of forewing venation were observed (Figs 4, 5). Both patterns feature a radial sector that does not reach the costal margin, and a media that connects between Rs+M and 2rs-m. The former character separates Malagasy Proceratium HNS from Discothyrea HNS and the genus PRm01, and the latter separates it from Probolomyrmex HNS .
In a study of world fauna that did not include taxa from Madagascar, Baroni Urbani and De Andrade (2003: 49) divided Proceratium HNS forewing venations into five categories. Their categories 4 and 5 are closest to the two patterns shown in Figs 4 and 5 for the Malagasy taxa studied here. However, in contrast to their categories 4 and 5, the Malagasy taxa have shorter 2r-rs. Also unlike their category 5, the media and 1m-cu are not always absent among the Malagasy specimens as in Figure 5. In a few specimens of one species ( Proceratium mgm HNS 01), the media and 1m-cu are still recognizable.