Pogonomyrmex laticeps Santschi 1922
Pogonomyrmex laticeps Santschi, 1922: 350 (worker). Syntypes
examined: 2 workers [MACN], #1376, ARGENTINA, Catamarca: Masao (Weiser leg.,
March 1921); Kusnezov, 1951: 274, figs. 10a, 10b (ergatoid queen, brachypterous
queen). See also Gallardo, 1932: 161, fig. 42; Peeters, et al. 2012: doi:10.1371/journal.pone.0047727,
figs. 2-4, 6-7 (MACN worker here designated LECTOTYPE).
Worker
Diagnosis. Within the P. laticeps-group, the combination of:
(1) head and mesosoma dark reddish-black, gaster black, (2) rugae on promesonotum
transverse, oblique, or irregular, rarely longitudinal, and (3) medial rugae along posterior margin of
head usually partly rugoreticulate uniquely
characterize this species.
Measurements
– lectotype (n
= 52). HL 2.04 (1.56-2.07); HW 2.20 (1.65-2.25); MOD 0.37 (0.30-0.40);
OMD 0.53 (0.39-0.64); SL 1.39 (1.08-1.59); PNW 1.38 (1.04-1.39); HFL 2.08 (1.45-2.24);
ML 2.67 (1.85-2.62); PW 0.55 (0.0.39-0.59); PPW 0.79 (0.59-0.83). Indices: SI 63.18 (60.34-81.52); CI 107.84 (101.12-115.20);
OI 16.82 (16.28-23.20); HFI 94.55 (81.22-110.56).
Description. Head weakly to moderately wider than long (CI
= 101.12-115.20), widest just posterior to eye; posterior margin flat in
full-face view. Longitudinal
cephalic rugae prominent, slightly wavy to irregular,
sometimes weakly rugoreticulate on medioposterior margin, in full-face view median rugae diverging slightly toward posterior corners of head. In side view, rugae posterior to eyes converging toward vertex; vertex rugose.
Cephalic interrugal spaces weakly granulate,
shining. Anterior
margin of clypeus flat to weakly concave; dorsal surface with numerous subparallel longitudinal rugae. Mandible with six teeth; mandibular
dorsum coarsely striated. Numerous long,
curved, bristle-like, yellowish hairs project from anterior margin of clypeus
and basolateral margin of mandibles. MOD ranging from 0.18-0.23x
HL. Eyes in profile situated near
middle of head, OMD = 1.19-1.60x MOD.
Antennal scapes relatively long (SI =
60.34-81.52), failing to reach vertex by up to length of basal funicular
segment; smooth and shining, distal portion often weakly striate. Basal flange of scape
flattened, well developed with carinate margin. Psammophore well
developed.
Mesosomal profile
flat to weakly convex; all mesosomal surfaces with
prominent rugae. In side and dorsal views,
humeral shoulders sometimes angulate, weakly elevated
above medial portion of pronotum. Dorsum of promesonotum and sides of pronotum
with coarse, transverse, longitudinal or oblique irregular rugae,
rugoreticulate, or vermiculate; promesonotal
suture slightly impressed on occasional workers. Mesopleura with
wavy to irregular rugae angling posterodorsally,
rugae often more irregular to rugoreticulate
near anterodorsal margin. Dorsum of propodeum with transverse to irregular rugae
that traverse anteroventrally on sides. Propodeum with long, acuminate spines connected by well defined keel; spine length
similar to or slightly longer than distance between bases. Inferior propodeal spines absent or reduced to indistinct rounded or
triangular process. Propodeal
spiracles narrowly ovate. Interrugal spaces on mesosoma
smooth, strongly shining. Legs moderately coriarious, weakly shining.
Petiolar peduncle about
0.8x as long as petiole, anteroventral
margin usually with a rounded to triangular tooth-like process. In side view, petiolar
node broadly but asymmetrically rounded with anterior surface about one-half as
long as posterior surface. Apex of node weakly angulate to
rounded. In dorsal view, petiolar node longer than wide, sides subparallel
to slightly wider near spatulate anterior margin; dorsum
and sides with moderately strong wavy to irregular, transverse to arc-shaped rugae. Dorsum of postpetiole convex in profile; in dorsal view, widest near posterior
margin, narrowing to anterior margin; maximal width about equal to length; dorsum
and sides with wavy to irregular transverse rugae
that are weaker, more closely spaced than on petiole. Interrugal spaces
smooth and strongly shining on petiole, weakly to moderately granulate, weakly shining
on postpetiole.
Dorsum of gaster moderately coriarious, weakly shining to smooth, strongly shining.
Erect
whitish pilosity moderately abundant on head,
variable in length, longest hairs not exceeding 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 gastral terga with moderately dense, erect setae, variable in
length, only those on posterior gastral terga approaching MOD. Head, mesosoma
dark orangish-black to reddish-black; petiole, postpetiole slightly darker; legs, gaster
dark brown to black.
Ergatoid queen
Diagnosis. This caste is diagnosed by: (1) larger species (HW > 1.40 mm), (2) first gastral tergum smooth and shining
to moderately coriarious, (3) cephalic interrugae smooth and shiny, and (4) head, mesosoma, petiole, postpetiole
dark reddish-black, gaster
blackish.
Measurements
- (n = 25). HL 1.85-2.18; HW
1.99-2.32; MOD 0.35-0.44; OMD 0.5-0.67; SL 1.25-1.65; PNW 1.28-1.45; HFL
1.83-2.24; ML 2.26-2.75; PW 0.49-0.64; PPW 0.78-0.96. Indices: SI 53.88-76.39; CI 104.19-113.00; OI
16.09-20.39; HFI 83.04-100.00.
Brachypterous queen
Diagnosis. This caste is diagnosed by: (1) in dorsal
view, mesoscutum poorly developed, anterior margin
barely surpassing humeral angles, (2) in lateral view, pronotum
meeting mesoscutum at shallow angle (approximately 45o),
(3) head, mesosoma dark reddish-black, gaster black, and (4) posterior margin of pronotum rugoreticulate.
Measurements
- (n = 30). HL 1.90-2.36; HW 2.09-2.49; MOD 0.40-0.46; OMD 0.55-0.69; SL
1.35-1.66; PNW 1.29-1.59; HFL 2.01-2.44; ML 2.26-2.87; PW 0.53-0.63; PPW
0.83-1.02. Indices: SI 57.26-70.09; CI
104.66-119.29; OI 16.46-19.66; HFI 84.10-102.14.
Male
Diagnosis.
Measurements
- (n = 12).
HL 1.20-1.43; HW 1.32-1.52; MOD 0.43-0.55; OMD 0.22-0.32; SL 0.34-0.42; HFL
1.50-1.96; ML 2.13-2.62; PW 0.44-0.58; PPW 0.65-0.81. Indices: SI 23.68-31.82; CI 103.50-122.58; OI 30.94-36.18; HFI
107.91-146.27.
Description.
Additional
material examined. ARGENTINA: Catamarca: Punta de
Balasto, no date (MACN); Rt 40 at 3.8 km S Punta de
Balasto, 7040’, Jan. 27, 2010 (RAJC); Catamarca, airport,
Feb. 4, 1967 (MCZ); Santa María (LACM; MCZ); Valle de Santa María, no date
(MCZ); Valle Masan, no date (MCZ). La Rioja: 96.8 km N Jct Rts 9 & 38, 1750’, Jan.
7, 2006 (RAJC); Rt 38 at 30.8 km SE Patquía, 1330’, Jan. 15, 2010 (RAJC); 18.0 km NW Patquía, 1970’, Jan. 20, 2006 (RAJC); 30.8 km E Jct Rts 5 & 38, 1160’, Jan.
21, 2006 (RAJC); Rt 40 at 6.0 km N Chilecito, 3200’,
Jan. 3, 2006 (RAJC); Rt 40 at 11.3 km N Chilecito,
3230’, Feb. 6, 2010 (RAJC); Rt
40 at 14.0 km N Chilecito, 3410’, Feb. 4, 2006 (RAJC); Rt
40 at 25.4 km W Shaqui, 4070’, Jan. 5, 2006 (RAJC); Rt 40 at 49.1 km S Pituil, 4270’, Jan. 20, 2006 (RAJC); Rt
73 at 60.7 km NE Chamical, 1430’, Jan. 21, 2006
(RAJC); Nonogasta, no date (MACN). Salta: Cafayate, 1650m (LACM; MCZ; MZUSP; RAJC; USNM); Rt 40 at 5.6 km N Cafayate, 5480’,
Jan. 11, 2006 (RAJC); Rt 40 at 28.4 km N Cafayate, 5400’, Jan. 11, 2006 (RAJC). San Luis: 3.7
km SE Jct Rts 20 & 147,
2380’, Dec. 27, 2005 (RAJC); Parque Nacional Sierra
las Quijadas, 2610’, Mar. 6, 2005 (RAJC); Rt 20 at
75.6 km W Luján, 1570’, Dec. 27, 2005 (RAJC). Tucumán: Rt
307 at 6.8 km NW Amaicha de Valle, 6080’, Jan. 27,
2010 (RAJC); Rt 40 at 10.0 km NW Amaicha
del Valle, 5940’, Jan. 10, 2006 (CASC; RAJC); SW Amaicha
de Valle, 2100m, Feb. 3, 1995 (MCZ); Bañado de Quilmes, no date (MACN).
Etymology. The
specific epithet, laticeps
(from Latin, latus
= wide, and the suffix –ceps
= head), is derived from the wide head of this species; in his description, Santschi noted that the head was clearly wider than long.
Discussion.
Pogonomyrmex laticeps is
not known to co-occur with P. mendozanus or
P. tinogasta.
Pogonomyrmex laticeps can
be distinguished from P. mendozanus by the coarse, irregular rugae
on the head and mesosoma, whereas rugae
on the head and mesosoma of P. mendozanus are fine and very regular. Pogonomyrmex laticeps can be distinguished from P. tinogasta based on the following
characters: (1) head and mesosoma dark reddish-black,
gaster black, (2) rugae on promesonotum transverse, oblique, or irregular, rarely
longitudinal, and (3) medial rugae along posterior
margin of head usually partly rugoreticulate. In P. tinogasta, the
body is concolorous black except for a dark reddish
band encircling eye, the promesonotal rugae are longitudinal, usually regular, and medial rugae along the posterior margin of head are longitudinal,
rarely rugoreticulate.
Several
authors have misinterpreted the type locality for P. laticeps. In describing the species, Santschi (1922) listed the type locality as
Masao, Catamarca Province, Argentina.
Gallardo (1932) later listed the type
locality as Masas, and Kempf
(1972) apparently questioned the
locality by indicating it as <Masao> (=Mazán?). Additionally, the label of a MCZ worker was
interpreted as Valle Masan (see also
Baldini & Scattolin, 1993).
REFERENCES