Acanthognathus rudis

Distribution based on Regional Taxon Lists
Neotropical Region: Brazil, Paraguay.

Biology
Nests in rotten wood.

Nomenclature

 *  rudis. Acanthognathus rudis Brown & Kempf, 1969: 100, figs. 1, 2, 4-10 (w.q.m.) BRAZIL. Wheeler, G.C. & Wheeler, J. 1969: 110 (l.). See also: Dietz & Brandão, 1993: 683; Bolton, 2000: 17.

Description
TL 4.2, HL 0.93, H\V 0.65 ( CI 70), ML o.68 ( MI  73) , WL o.86, petiole  L in dorsal view 0.55, postpetiole L 0.20 (W 0.20) , gaster L 0.97, greatest diameter of compound eye o. 3, scape L ( chord to basal collar ) o.76 mm. Standard measure­ments of a selection of specimens from the type series are listed in Table   I. This species is so well known ( under the name ocellatus )  that Figs. I, 2,  and  4,  and  the measurements  and indices, plus mention of  a f ew outstanding features, should suffice to characterize it. Note the rather V-like outline of the posterior excision of the head. Head slightly more  depressed,  less  convex  above,  than  in  A.  ocellatus. The outstanding trait is the fine, nearly opaque, densely rugulose­ punctulate sculpture  of  head  and  truncus. Among the  rugules  are crowded numerous small piligerous fossae, especially on the dorsum of the head, but these are clearly visible only in certain lights. Sides of truncus finely punctulate-rugulose,  except for the lowest part of the mesothorax,  which  is smooth  and shining. The hairs are abun­dant,  particularly  on  head  and  promesonotum,  but  also present  on nodes,  short  and inclined,  slender  but  blunt,  of ten  f eebly flattened or clavate toward  their apices,  those on the head  directed  anteriad. Pilosity otherwise as described  for the genus. Humeral angles obtuse, not strongly projecting. Propodeal teeth diverging, very feebly curved as seen from above. The mandibles lack preapical armament, and there is not even a distinct welt at the site of the trigger hair, though a formation extending internally to the base of the hair can be seen within the transparent cuticle  of  the  inner  mandibular  margin. Petiole with a low, rounded node ( Fig. 2), the  lower  anterior slope with a low median carina ; node about 0.22 mm long and o.r 8 mm wide ; postpetiole subglobular. Petiole and  postpetiole  densely and finely reticulo-punctulate and opaque, except for the almost completely smooth, shining nodal summits. Color light reddish ferruginous ; nodes and gaster yellowish fer­ruginous; but the gaster with the middle third shading into a broad brownish-red  transverse  band ; appendages  yellow  to  straw. Para type variation is slight on the whole (see Table I ). Workers from Boraceia, S. Paulo State, have the upper as well as lower mesopleura largely smooth  and  shining. Color varies  from  light to medium  ferruginous. Measurements of a queen from the type locality are given in Table I. Her distinguishing specific characters correspond in the usual way to those of the worker. Mesonotum with crowded, slightly vermiculate longitudinal rugulae, interspersed with small fossae. Pronotum and propodeum transversely  rugulose. Mesopleura with the upper half rugulose or smooth ; lower half mostly smooth and shining. TL 2.8, HL 0.52, HW without eyes 0.45, with eyes 0.54, L antenna 2.0, ML 0.05, WL 0.90, L forewing 2.55  mm. See Figs. 5-10. Smooth and shining,  with  small  punctures abundant on head, a few rugae around the antenna! insertions. Mesonotum finely and indistinctly longitudinally striolate-punctulate, sericeous-opaque. Color brown to piceous, head darkest (specimens may not be fully colored ). Legs and mouthparts yellowish-tan.
 * Holotype worker :
 * Queen :
 * Male from the type nest series: