Acanthognathus poinari

From our analysis, however, A. poinari appears to be one of the most specialized species of the genus Acanthognathus which, in turn, appears to be one of the most specialized dacetine genera.

Identification
An Acanthognathus species distinguishable from all other known ones for the transverse rugulation on the posterior cephalic angles. At first glance, A. poinari appears most closely related to A. brevicornis (Panama to Rio Grande do Sul in Brazil) or teledectus (Costa Rica and Colombia), two species with which it shares a relatively smooth integument. Since the genus Acanthognathus contains a small number of well-defined species (7, inclu­ding A. poinari, with the 6 extant ones already revised by BROWN & KEMPF, 1969) we attempted a cladistic analysis of all of them in order to trace the phylogenetic position  of  the Dominican  fossil.

Distribution
This taxon was described from Dominican Amber (Miocene).

Nomenclature

 * † poinari. †Acanthognathus poinari Baroni Urbani, in Baroni Urbani & De Andrade, 1994: 41, figs. 20, 21, 26, 27 (q.) DOMINICAN AMBER (Miocene). See also: Bolton, 2000: 17.

Description
Head (Fig. 27) elongate, with nearly straight sides gradually converging anteriorly, feebly emarginate occipital border and angulate posterior cor­ ners. Compound eyes oval, slightly protruding and situated in the middle of the head sides. Anterior border of clypeus irregularly rounded and only feebly protruding. Scapes and mandibles shorter than head length. Antennae with clearly two-jointed club. Trunk short and globose, with a flat dorsal plane constituted by part of the meso­ and metanotum; the latter descending abruptly posteriorly in profile. Propodeal spines pointed, relatively short, directed upwards. Propodeal declivity only slightly concave. Petiole three times longer than broad, with a long anterior peduncle and rounded node in profile. Postpetiole slightly longer than broad with  comparably  rounded node. Gaster round in dorsal view. Wings: fore wings with marked pterostigma and R+Sc, traces of M +CuA and 2r. Other veins partially or completely indistinguishable. Hind wings only with a long portion of M +CuA clearly visible. Sculpture: dense, deep polygonal fossae diminishing in density and deep from the genae towards the vertex; the vertex proper with transverse striae continuing longi­tudinally over the posterior half of the sides of the head and on its ventral face. Trunk very slightly longitudinally striate and with effaced fossae. Petiole and postpetiole covered by feeble, longitudinal striae, partly effaced on the petiolar node and com­pletely so on the postpetiolar one. Posterior borders of the first and second gastral segments with longitudinal costulations. Rest of the body smooth or slightly punc­tate only. Pilosity: sparse, short, pointed, suberect or erect hairs on the dorsum of the head. Similar, slightly longer hairs on the trunk and abdominal peduncle. Scape, mandibles and legs with rare, sparse hairs slightly shorter than those on the head, pointed and semi-decumbent. Dense, very short, pointed and decumbent hairs on the funicular joints, much sparser on the gaster. Colour reddish-brown, shining, with slightly lighter antennae and legs.