Pogonomyrmex pronotalis Santschi 1922
Pogonomyrmex pronotalis Santschi,
1922: 350 (worker). Syntypes examined: 2 workers [MACN],
3 workers [NHMB], #1395, ARGENTINA, Mendoza: Cordillera de Mendoza, Cajón de Guanaco (Dr. Carette).
See also Gallardo, 1932: 149 (MACN worker here designated LECTOTYPE).
Worker
Diagnosis. The combination of: (1) dorsum of first gastral tergum lacking striae, (2) irregular, widely spaced rugae
on dorsum of head and mesosoma, and (3) bicolored; head, mesosoma,
petiole, postpetiole mostly blackish to black, gaster ferruginous orange uniquely characterize this
species.
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), widest just
posterior to eye; posterior margin flat in full-face view. Longitudinal cephalic rugae prominent, widely spaced, wavy to irregular, in
full-face view median rugae diverging toward
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 to moderately granulate, weakly to strongly 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 margin 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, moderately shining to
smooth and shining. Basal flange of scape moderately well developed with carinate
margin. Psammophore
well developed.
Mesosomal profile weakly
convex; all mesosomal surfaces with prominent rugae. In side and
dorsal views, humeral shoulders enlarged, angulate. 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 posterodorsally. Dorsum of propodeum with irregular transverse rugae
that traverse anteroventrally on sides. Propodeum with
long, blunt to acuminate spines connected by well defined keel; spines slightly
shorter than distance between bases. Inferior propodeal spines well-developed,
triangular, wider than tall, with rounded to subacute
tip. Propodeal spiracles narrowly ovate. Interrugal spaces
on mesosoma moderately to strongly granulate, dull to
weakly shining. Legs weakly coriarious, weakly shining to smooth, shining.
Petiolar peduncle about
as long as petiole, anteroventral margin usually with
rounded triangular process. In side view, dorsum of petiole weakly 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 wide, 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, narrowing 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
weakly granulate, weakly shining to smooth and shining. Dorsum of gaster moderately coriarious, weakly
shining to smooth and strongly 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, gastral terga with moderately
dense, erect setae, mostly similar in length, longest about 0.7x MOD. Head, mesosoma, funicular
segments, legs, 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 terga.
Queen.
Unknown.
Male.
Unknown.
Additional material examined. ARGENTINA: Mendoza: Valle
Hermosas, 7430’, Dec. 6, 2003 (CASC; RAJC); Rt 145 at 42.2 km W Bardas Blancas, 5380’, Jan. 26, 2008
(RAJC).
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 …”.
Discussion. Pogonomyrmex pronotalis has been
confused with P. mendozanus,
with the latter having been misidentified as the former in several publications
(see above). Pogonomyrmex pronotalis is separated from P. mendozanus by
the widely spaced, irregular rugae on the dorsum of
the head and mesosoma, whereas these rugae are closely spaced, regular, and subparallel/parallel
in P. mendozanus. Pogonomyrmex pronotalis co-occurs with or near P. santschii and P. catanlilensis, and it also might be confused with P. granulatus. Pogonomyrmex pronotalis is separated from P. santschii, P. catanlilensis,
and P. granulatus
by the lack of striae on the first gastral tergum (all three latter species
have striae on the first gastral
tergum).
The
location of the type locality for P. pronotalis (Cajon Guanaco, Cordillera Mendoza) is
unclear given that it could not be located in Mendoza Province. However, there is a Cajon Guanaco in Maule,
Chile, which is likely to be the actual type locality given that it is approximately
three km from the border of Mendoza Province.
REFERENCES