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Extant: 2 tribes, 3 genera, 146 species
Fossil: 1 genus, 12 species
(Figs 6, 12, 22-24, 30, 34)
Since only a single male specimen of this genus has been collected so far, we do not describe it as new here. However, we regard this male as belonging to an isolated genus, and its diagnostic characters and remarks are given below.
With characters of ProceratiinaeHNS. Mandible stout and shaped like a curved short blade such as a jambiya (Fig. 30). Frontoclypeal region not projecting dorsally. Frontal carinae merged into single carina between antennal sockets. Antennal sockets opening dorsally. Antenna with 12 segments. Labrum triangular: narrowed apically, with a single apex (Fig. 30). Second segment of the maxillary palp not hammer-shaped (Fig. 34). Pro- and metatibia with a single spur, mesotibia without spurs. Pygostyles absent.
On forewing, costa and radius completely developed, and radial sector reaches to the costal margin (Fig. 6). On hindwing, free section of radius and cubitus absent, radial sector, M+Cu, and cu-a crossvein present (Fig. 12).
Remarks. The undescribed genus PRm01 can be distinguished easily from the other three Malagasy proceratine genera by the antennae consisting of 12 segments, a triangular labrum (Fig. 30), and the mesotibiae lacking a spur. PRm01 sp. is the first male known in ProceratiinaeHNS with a 12-segmented antenna. Bolton (2003: 49) has proposed 13-segmented antenna as a diagnostic character of both tribes in ProceratiinaeHNS; this now must be amended.
There is one erroneous report of a12-segmented antenna in ProceratiumHNS. Kennedy and Talbot (1939) previously described a male of Proceratium silaceum RogerHNS, 1863, and included a drawing and description of a male with a 12-segmented antenna (their figure 1). However, their figure 6 illustration shows an antenna with 13 segments for the same species. As Brown (1958) has pointed out, their figures and description disagree in palpal formula, and we conclude they also differ in antennal count. Baroni Urbani and De Andrade (2003: fig. 162) have included an SEM image of a male of Proceratium silaceumHNS, on which the antenna clearly consists of 13 segments. Therefore, males of ProceratiumHNS have 13-segmented antennae and not 12 as erroneously reported by Kennedy and Talbot (1939).
The triangular labrum is a unique character for PRm01 within the ProceratiinaeHNS (Fig. 30). An apically bilobed labrum is the usual pattern in the Formicidae (Gotwald 1969). The triangular labrum, a wide and bilobed clypeus, and stout mandibles with outward curved masticatory margins should be expected in conspecific workers. These characters may have a special function.
FIGURES 27-28. Labrum of proceratine males. Basal margin on top. 27, Discothyrea mgm01 (CASENT0083245) in internal view; 28, Probolomyrmex mgm01 (CASENT0525318) in external view.
FIGURES 29-30. Proceratine males. 29, Labrum of Proceratium mgmHNS 01 (CASENT0191991) in external view, basal margin on top; 30, Labrum and mandibles of PRm01 sp. (CASENT0103485) in oblique full-face view.
FIGURES 31-32. Mouthparts of proceratine males. 31, Discothyrea mgm01 (CASENT0083245), left palps on right side; 32, Probolomyrmex mgm01 (CASENT0525318), left palps on top.
Only a single specimen was collected from the Seychelles (CASENT0103485). Similarity in forewing venations between PRm01 (Fig. 6) and DiscothyreaHNS (Fig. 2) suggests their close relationship (see DiscothyreaHNS section above); however, the male of PRm01 can be distinguished easily from those of DiscothyreaHNS by the following characters: frontoclypeal region not expanded dorsally, 12-segmented antennae, triangular labrum (Fig. 30), longer second maxillary palpal segment (Fig. 34), absence of pygostyles, lack of a mesotibial spur, presence of cu-a in hindwing (Fig. 6), larger size, and brighter color, as PRm01 is yellowish-brown (Fig. 22), while DiscothyreaHNS is black (Fig. 19). Formal description of this taxon awaits the future collection of additional males and the first workers.