Pogonomyrmex pronotalis Santschi

 

Pogonomyrmex pronotalis Santschi, 1922: 350 (worker). Syntypes examined: 2 workers [MACN], Cajón de Guanaco, Cordillera de

      Mendoza, Mendoza Province, Argentina (Dr. Carette).  See also Gallardo, 1932: 149.

 

Lectotype designation.  A syntype is designated as the lectotype of P. pronotalis in order to stabilize the identity of this taxon.  The identity of the specimen is indicated by a label and the specimen is deposited at MACN.  High resolution photographs of the lectotype are available at ANTWEB (http://www.antweb.org/).  High resolution photographs of the lectotype are available at ANTWEB (http://www.antweb.org/).

Worker

Diagnosis.

Measurements – lectotype (n = 12). HL 1.76 (1.58-1.82); HW 1.81 (1.61-1.81); MOD 0.38 (0.34-0.40); OMD 0.42 (0.41-0.49); SL 1.36 (1.16-1.44); PNW 1.21 (1.10-1.22); HFL 1.75 (1.64-1.87); ML 2.10 (1.93-2.38); PW 0.40 (0.43-0.51); PPW 0.60 (0.56-0.65).  Indices: SI 75.14 (69.14-79.63); CI 102.84 (95.27-106.10); OI 20.99 (20.99-24.39); HFI 96.69 (97.73-106.90).

Description.  Head subquadrate to quadrate (CI = 95.27-106.10), broadest just posterior to eye; posterior margin flat in full-face view.  Longitudinal cephalic rugae prominent, wavy to slightly irregular, in full-face view median rugae diverging towards posterior corners of head; medial posterior margin with transverse to oblique rugae.  In side view, rugae posterior to eyes converging at or near vertex; vertex rugose.  Interrugal spaces on vertex smooth, strongly shining to moderately granulate, sub-shining; cephalic interrugal spaces strongly granulate, dull.  Anterior margin of clypeus concave; dorsal surface with numerous subparallel longitudinal rugae.  Mandibles with six to seven teeth (20% had six teeth, 46% had seven teeth) or a different number on each mandible (31% with six/seven teeth, 3% with seven/eight teeth; n = 35); mandibular dorsum coarsely striated.  Numerous long, curved, bristle-like, cream to light yellowish hairs project from anterior edge of clypeus and basolateral margin of mandibles.  MOD ranging from 0.21-0.26x HL.  Eyes in profile situated slightly anterior to middle of head, OMD = 1.07-1.35x MOD.  Antennal scapes relatively long (SI = 69.14-79.63), ranging from failing to reach vertex by up to length of basal funicular segment to reaching vertex; weakly striate, sub-shining to smooth and shining.  Basal flange of scape moderately well developed with carinate margin.  Psammophore well developed.

Mesosomal profile slightly convex.  In side and dorsal views, humeral shoulders enlarged, angulate.  All mesosomal surfaces with prominent rugae.  Dorsum of promesonotum with coarse, irregular longitudinal rugae that diverge anteriorly toward humeral angles, medial anterior margin with transverse to oblique rugae, pronotal sides rugoreticulate to vermiculate.  Mesopleura with irregular rugae angling posteriodorsally.  Dorsum of propodeum with irregular transverse rugae that traverse anterioventrally on sides.  Propodeum with long, subacute to acute spines connected by a well defined keel; spines slightly shorter than distance between their bases.  Inferior propodeal spines consist of a triangular process with a rounded to subacute tip.  Propodeal spiracles narrowly ovate.  Interrugal spaces on mesosoma moderately to strongly granulate, dull to sub-shining.  Legs weakly coriarious, sub-shining to smooth, shining.  

Petiolar peduncle long, ventral surface usually with a rounded triangular process.  In side view, dorsum of petiole slightly convex; petiolar node asymmetrical with anterior surface notably shorter than posterior surface, apex of node weakly rounded to angulate.  In dorsal view, petiolar node longer than broad, narrowest at posterior margin, gradually widening to spatulate anterior margin; dorsum and sides with moderately strong wavy transverse rugae.  Dorsum of postpetiole convex in profile; in dorsal view, widest at or near posterior margin, tapering to anterior margin; maximal width about equal to length; dorsum and sides with wavy transverse rugae that are weaker and more closely spaced than those on petiole.  Interrugal spaces on posterior face of petiole and dorsum of postpetiole smooth and shining to weakly granulate, sub-shining.  Dorsum of gaster smooth and strongly shining to moderately coriarious, sub-shining.

Erect whitish pilosity moderately abundant on head, variable in length, usually 1-2 long hairs near vertex and on frontal lobes that approach to slightly exceed MOD.  Moderately abundant suberect to semidecumbent pilosity on scape, abundant decumbent hairs on funicular segments.  Legs with moderately abundant semidecumbent white setae.  Mesosoma, petiole, postpetiole, and gastric tergites with moderately dense, erect setae, mostly similar in length, longest about 0.7x MOD.  Head, mesosoma, funicular segments, legs, and petiole black, often with an orangish tinge on mandibles, legs, and near vertex; postpetiole blackish-orange, gaster ferruginous orange, often with darker tranverse bands on posterior margin of tergites.

Queen. Unknown.

Male. Unknown.

Additional material examined.  ARGENTINA: Mendoza: Valle Hermosas, 7430’; Rt 145 at 42.2 km W Bardas Blancas, 5380’.

Etymology.  The specific epithet, pronotalis (Latin, from pronoto- for pronotum, plus –alis = suffix added to noun stems, meaning pertaining to), is derived from the wide pronotum, which Santschi described as: “middle of the pronotum wider than the mesonotum”.