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Oecophylla HNS F. Smith

Worker medium-sized, slender, slightly polymorphic. Head rather large, broader behind than in front, with rounded sides and posterior corners and semicircularly excised occipital border, very convex above. Eyes large, convex, broadly elliptical, situated in front of the middle of the head. Ocelli absent. Palpi very short, maxillary pair 5-jointed, labial pair 4-jointed. Mandibles long and large, triangular, with nearly straight lateral borders, a very long curved apical tooth and numerous short denticles along the straight apical border. Clypeus very large and convex, but not distinctly carinate, its anterior border entire or very feebly sinuate in the middle, depressed and projecting over the bases of the mandibles. Frontal area rather large, subtriangular; frontal carinae moderately long, subparallel. Antenna; very long, 12- jointed, the scapes inserted some distance from the posterior corners of the clypeus, rather abruptly incrassated at their tips; the first funicular joint very long and slender, longer than the second and third together, joints '2 to 5 much shorter, subequal, slender, the remaining joints, except the last, shorter and distinctly thicker. Thorax long and narrow; pronotum longer than broad, evenly convex above, narrowed and colliform anteriorly; mesonotum anteriorly long and constricted, subcylindrical, suddenly broadened behind where it joins the small, short, unarmed epinotum, which is rounded and convex above and without distinct base and declivity. Petiole long and slender, much longer than broad, subcylindrical, with a very low rounded node near its posterior end, its ventral surface near the middle more or less convex, its posterior border on each side with a small rounded, projecting lamella, appearing like an acute tooth when the segment is viewed from above. Gaster short, broadly elliptical, its first segment suddenly contracted to the petiole, the tip rather pointed. Legs very long and slender; claws, pulvilli, and last tarsal joint enlarged. Gizzard with long slender sepals, which are not reflected at their anterior ends.

Female much larger than the worker. Head broad, sub triangular; eyes not much larger than in the worker; ocelli well developed Thorax and gaster very broad and massive, flattened above; thorax nearly as broad as long, pronotum small and vertical, overhung by the large depressed mesonotum; epinotum nearly vertical. Petiole short and stout, broader than long, its node low and rounded, more or less impressed in the middle, obliquely truncated or concave behind. Gaster short, nearly as broad as long. Wings very long and ample, decidedly longer than the body, heavily veined, with a narrow closed radial, a large single cubital, and no discoidal cell.

Male somewhat smaller than the largest workers. Head small, broader than long, with very prominent, hemispherical eyes and moderately large ocelli. Mandibles very small, spatulate, with a few minute denticles. Antennae slender and rather short, 13-jointed; scapes elongate, their apical halves somewhat abruptly incrassated; first funicular joint clavate, enlarged at tip, slender at base; remaining joints much shorter, except the last, and slender. Thorax short and massive, the mesonotum broader than the head, very convex and gibbous in front where it overhangs the small mesonotum. Petiole and gaster similar to those in the worker, but the former more flattened above and without a node. Genital appendages very small, narrow, linear; legs long and slender, tarsal claws obsolete, but pulvilli well-developed. Wings ample, distinctly paler than in the female. Head, thorax and gaster much more pilose than in the worker and female.

Pupae not enclosed in cocoons.

This interesting genus is confined to the Old World tropics and ranges over the Indomalayan, Papuan, and Ethiopian Regions, but does not occur in Madagascar (Map 37). It comprises the famous and vicious "tree-ants," or "tailor ants," which make peculiar globular or elliptical nests of leaves on living trees. The leaves are spun together with films of white silk, which is supplied by the larvae. Numerous observers, notably Holland and Green, Wroughton, Rothney, Dodd, Saville Kent, Doflein, Bugnion, the Sarasin Brothers, Jacobson, Kohl, and myself, have described the extraordinary manner in which the workers use the young larvae as animated shuttles.

According to the majority of myrmecologists, the genus Oecophylla HNS , comprises only a single species, smaragdina (Fabricius) HNS , with several geographical races and varieties. A study of the materials that have been accumulating in my collection for the past twenty years, together with the fine series of specimens taken by Lang and Chapin in the Congo, has convinced me that there are really two distinct species: Oe . smaragdina, (Fabricius) HNS of the Indomalayan and Papuan Regions, with the varieties selebensis HNS Emery, gracilior HNS Forel, and gracillima HNS Emery and the subspecies subnitida Emery and virescens (Fabricius) HNS ; and ( E. longinoda (Latreille) HNS of the Ethiopian Region, with the varieties textor Santschi HNS , rubriceps HNS Forel, annectans HNS , new variety , and fusca HNS Emery. Ern. Andre described a form brevinodis HNS , from Sierra Leone, as a distinct species, and Stitz has recently cited it from Spanish Guinea, remarking that longinoda HNS occurs on the coast, brevinodis HNS in the hinterland, and that there are no transitions between the two. He implies also that brevinodis HNS does not make silken nests like longinoda HNS . The abundant Congo series from various nests shows, however, without the slightest doubt, that brevinodis HNS is nothing but the worker minima of longinoda HNS (see Fig. 58c), as Emery maintained as long ago as 1886, and the localities of the material before me show that this species is not confined to the west coastal region. It occurs also in East Africa, Santschii variety textor HNS being from Zanzibar. Several authors have cited the true smaragdina- from East Africa. Unfortunately I have little material from that region and what I have is certainly longinoda HNS , presumably belonging to textor HNS , though this variety seems to me to be poorly characterized and possibly not distinct from the typical form of the species. I am unable to say, therefore, whether Oe. smaragdina HNS , actually occurs on the African continent.

Map 37. Distribution of the genus Oecophylla HNS .

According to Emery, longinoda HNS is the most primitive of the existing forms of Oecophylla HNS , because most closely allied to Oe. sicula HNS , which he described from the Miocene amber of Sicily. In the Baltic amber I have recognized two species of the genus, Oe. brischkei Mayr HNS and brevinodis Wheeler HNS . As the latter name is preoccupied by brevinodis Andre HNS , which was based, as I have shown, on the minima worker of longinoda HNS , I suggest that the fossil species be called crassinoda HNS (new name). In the shape of the petiole both of the Baltic amber forms, being of Lower Oligocene age and therefore older than sicula HNS , are also more like longinoda HNS , and especially its smaller workers, than the Oriental smaragdina HNS .

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Plazi

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