Pogonomyrmex lobatus Santschi
Pogonomyrmex lobatus Santschi,
1921: 96 (worker). Syntypes examined: 1
worker [MZUSP], 1 worker [MCZ], Villaguay, Entre
Ríos
Province, Argentina (Charles
Bruch leg.). See also Gallardo, 1932: 160, fig. 41: Kusnezov,
1951: figs. 13b, 13c.
Lectotype
designation.
A syntype is designated as the lectotype of P. lobatus 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
MCZ. High resolution photographs of the lectotype are available at ANTWEB (http://www.antweb.org/).
Worker
Diagnosis. Pogonomyrmex lobatus is
separated from other species in the P. coarctatus-group based on the following combination of
characters: longitudinal cephalic rugae very fine and
dense over entire head; in side view, massively enlarged lateral lobe of
clypeus with a narrow gap (much less than width of antennal scape)
between lateral lobe and frontal carina, the latter two structures nearly
contacting one another; entire body mostly concolorous
reddish-orange to reddish-brown.
Measurements
(mm) - lectotype (n
= 41). HL 2.31 (1.93-2.97); HW 2.39 (1.99-3.22); MOD 0.43
(0.38-0.60); OMD 0.43 (0.46-0.74); SL 1.42 (1.27-1.90);
Description. Moderately
polymorphic, but lacking supermajors. Head shape varies with worker size, quadrate
in minors and increasingly more broad than long in majors (CI = 101.00–113.33,
positively associated with head width, n
= 42, R2 = 0.28, P <
0.001); broadest just posterior to eye, posterior margin slightly concave
medially in full-face view. Longitudinal cephalic rugae very fine and
dense over entire head, width of rugae and interrugae similar; in full-face view median rugae not diverging toward posterior corners of head. Vertex smooth and shining,
or with very fine, dense rugae, sub-shining to
shining interrugal spaces. Cephalic interrugal
spaces dull to sub-shining. In full-face view, entire head with a silky appearance. Anterior margin of clypeus concave; dorsal
surface with more than 10 moderately coarse subparallel, longitudinal to oblique rugae. In side view,
lateral lobe of clypeus massively enlarged with a narrow gap (much less than
width of antennal scape) between clypeal lobe and
frontal carina, the latter two structures almost in contact. Numerous long, curved,
bristle-like, yellowish macrochaetae projecting from
anterior margin of clypeus and underside of mandibles. Mandible with six teeth; mandibular
dorsum strongly striated. MOD ranging from 0.16–0.23x HL. Eyes in profile situated anterior to middle
of head, OMD = 1.00–1.51x MOD. Antennal scapes short (SI = 55.21–70.00), extending beyond posterior
margin of eye by less than length of first two funicular segments. Base of antennal scapes
smooth and shining, distal portion sometimes weakly granulate or weakly
striate, sub-shining to shining; basal flange well developed with carinate margin. Psammophore moderately well developed.
Mesosomal profile
slightly to distinctly convex. In dorsal view, humeral portion of pronotum rounded to knoblike. All mesosomal
surfaces with prominent coarse, subparallel, slightly
irregular, widely spaced rugae. Dorsum of promesonotum with longitudinal rugae
that rarely diverge anteriorly toward humeral
angles; transverse rugae on anterior face of pronotum continue obliquely or longitudinally on pronotal sides; rugae on mesopleura angle posteriodorsally. Propodeal spines
long, strongly tapered, with acute tips, connected by a well-defined keel;
spine length about equal to or slightly less than width between their bases;
regular to slightly wavy transverse rugae on propodeal dorsum traverse ventrally or anterioventrally
on sides. Inferior propodeal
spine broader than long, apex broadly rounded.
Propodeal spiracles narrowly ovate.
Interrugal spaces on mesosoma
weakly to moderately granulate, sub-shining to shining. Legs weakly granulate, sub-shining.
Petiolar peduncle long, ventral surface with a broadly rounded to angulate process.
In side view, dorsum of petiole slightly convex; petiolar
node asymmetrical with anterior surface notably shorter than posterior surface,
apex of node rounded to ovate. In dorsal
view, petiole longer than broad, widest near center, tapering to a rounded or spatulate anterior margin.
Sides and dorsum of petiole with weak to moderately
coarse, wavy to irregular transverse rugae. Dorsum of postpetiole convex in profile; in dorsal view, widest near
posterior margin, tapering to anterior margin, maximum width about equal to
length, weakly to moderately punctate, rarely with
weak irregular transverse rugae on posterior
half. Interrugal
spaces on petiole and postpetiole weakly to
moderately granulate, dull to sub-shining.
Dorsum of gaster smooth,
moderately coriarious, sub-shining to shining.
Erect white to yellowish pilosity moderately abundant on head, variable in length
and arising from fovea; longest hairs not exceeding MOD. Moderately abundant suberect pilosity on scape; abundant decumbent hairs on funicular segments.
Legs with moderately
abundant suberect to decumbent setae. Mesosoma, petiole, postpetiole, and first gastric
tergite with moderately dense erect setae, longest
about equal to MOD; abundant long hairs on margins of posterior gastric tergites, longest greater than MOD. Entire body concolorous reddish-orange to reddish-brown, head often
slightly lighter in color.
Queen
Diagnosis. As in worker diagnosis, but with
caste-specific morphology of the mesosoma related to
wing-bearing, presence of small ocelli on head, and
as illustrated in Figure 6. Queens are
also large (HW = 3.41-3.55 mm).
Measurements
(mm) - (n = 5). HL 3.09-3.24; HW
3.41-3.55; MOD 0.53-0.60; OMD 0.67-0.77; SL 1.87-1.93; PNW 2.37-2.51; HFL
2.61-2.77; ML 3.74-4.44; PW 1.02-1.16; PPW 1.25-1.33. Indices: SI 53.12-56.27; CI 105.25-114.89; OI
15.45-17.01; HFI 75.65-78.69.
Description. As in
worker diagnosis, but with caste-specific morphology of the mesosoma
related to wing-bearing, presence of small ocelli on
head, and as illustrated in Figure 6.
Large species (HW = 3.41-3.55 mm); in full face view, head broader than
long (CI = 105.2–114.9), posterior margin slightly concave medially. Longitudinal cephalic rugae very fine and dense over entire head; striae on vertex often less abundant and/or less prominent. Interrugal spaces sub-shining to shining. Mandible with six teeth,
dorsal surface coarsely rugose. In side view, lateral lobe of clypeus
massively enlarged with a narrow gap (much less than width of antennal scape) between clypeal lobe and frontal carina, the latter
two structures almost in contact. Psammophore moderately well developed.
All mesosomal surfaces with subparallel,
slightly irregular rugae; propodeum
with two short spines. Petiolar
peduncle long, ventral surface often with a blunt to angulate
process. In side view, petiolar node asymmetrical with anterior surface notably
shorter than posterior surface, apex of node rounded. Postpetiole slightly more broad than long. Dorsum of petiole and postpetiole with weak to moderately strong wavy to
irregular transverse rugae; interrugal
spaces weakly to moderately punctate, sub-shining. Gastric tergites
smooth, sub-shining to shining. Most
body surfaces with moderately abundant suberect to
erect, short white to yellowish setae. Entire body concolorous reddish-orange to
reddish-brown, head often slightly lighter in color.
Male
Diagnosis.
Measurements
(mm) - (n = 12). HL 1.83-2.06; HW
1.78-2.14; MOD 0.56-0.70; OMD 0.21-0.36; SL 0.45-0.61; HFL 2.18-2.61; ML 3.39-4.04;
PW 0.74-0.93; PPW 0.90-1.12. Indices: SI
22.39-30.90; CI 93.47-105.94; OI 29.47-36.52; HFI 109.95-129.83.
Description.
Additional material examined.
Etymology. The specific epithet, lobatus (from
Latin, lobat = lobed), refers to the massively
enlarged lateral lobes of the clypeus.
Discussion
Pogonomyrmex lobatus is known to
co-occur with P. coarctatus,
and it is likely to co-occur with P. micans. Pogonomyrmex lobatus can
be distinguished from P. coarctatus using
the following characters: (1) P. lobatus has a massively enlarged lateral lobe of the
clypeus, with the lobe nearly contacting the frontal carinae,
and (2) the entire head is covered with very fine, dense longitudinal rugae. In P. coarctatus, the
lateral lobe of the clypeus is not enlarged, with a wide gap between the lobe
and the frontal carinae, and the very fine, dense
longitudinal cephalic rugae are often indistinct and
only cover part or most of the head. In P. micans the
lateral lobe of the clypeus is not enlarged, the dorsum of the postpetiole has prominent moderately coarse rugae, and workers are bicolored
(dark red and blackish). In P. lobatus,
the lateral lobe of the clypeus is massively enlarged, workers are a concolorous reddish-orange to reddish-brown, and the dorsum
of the postpetiole is weakly to moderately punctate, rarely with weak rugae
on posterior half. Pogonomyrmex marcusi is only known from mid- to
higher elevation areas of central