Pogonomyrmex lobatus Santschi 1921
Pogonomyrmex lobatus Santschi, 1921: 96 (worker). Syntypes examined: 6 workers [MACN], 1 worker [MZUSP], 1 worker [MCZ], ARGENTINA, Entre Ríos: Villaguay
(Charles Bruch leg.). See also Gallardo, 1932: 160, fig. 41; Kusnezov, 1951: figs. 13b, 13c (MCZ worker here designated LECTOTYPE).
Worker
Diagnosis. Within the P. coarctatus-group, the combination of:
(1) longitudinal cephalic rugae very fine and dense
over entire head, (2) in side view, massively enlarged lateral lobe of clypeus
with narrow gap between lateral lobe and frontal carina, the latter two
structures nearly in contact, and (3) body mostly concolorous
reddish-orange to reddish-brown uniquely characterize this species.
Measurements
- 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 wider than long in majors (CI = 101.00–113.33,
positively associated with head width, n
= 42, R2 = 0.28, P <
0.001); widest just posterior to eye, posterior margin weakly 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 with very fine, dense rugae,
interrugal spaces weakly shining to smooth and
shining. Cephalic interrugal spaces dull to weakly shining. In full-face view, entire
head with silky appearance.
Anterior margin of clypeus concave; dorsal surface with numerous moderately
coarse subparallel,
longitudinal to oblique rugae. In side view, lateral lobe of clypeus massively
enlarged with narrow gap (much less than width of antennal scape)
between clypeal lobe and frontal carina, the latter two structures nearly in
contact. Numerous long, curved,
bristle-like, yellowish macrochaetae project from anterior margin of clypeus and ventral side 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, weakly shining to
shining; basal flange well developed with carinate
margin. Psammophore
moderately well developed.
Mesosomal profile
slightly to moderately convex; all mesosomal
surfaces with prominent coarse, subparallel, weakly irregular,
widely spaced rugae.
In dorsal view, humeral portion of pronotum
rounded to knoblike. 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 posterodorsally. Superior propodeal
spines long, acuminate, connected by well-defined keel; spine length about
equal to or slightly less than width between bases; regular to slightly wavy
transverse rugae on propodeal
dorsum traverse ventrally or anteroventrally on
sides. Inferior propodeal
spines wider than long, apex broadly rounded.
Propodeal spiracles narrowly ovate.
Interrugal spaces on mesosoma
weakly to moderately granulate, weakly shining to shining. Legs weakly granulate, weakly shining.
Petiolar
peduncle about 0.7x as long as petiole, anteroventral
margin with broadly rounded to angulate process. In side view, posterior surface of petiole weakly
convex; petiolar node asymmetrical with anterior
surface notably shorter than posterior surface, apex of node rounded to
ovate. In dorsal view,
petiole longer than wide, widest near center, narrowing to rounded or spatulate anterior margin. Sides and posterior surface
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, narrowing to
anterior margin, maximum width about equal to length, weakly to moderately punctate, rarely with weak irregular transverse rugae posteriorly. Interrugal spaces
on petiole and postpetiole weakly to moderately
granulate, dull to weakly shining. Dorsum of gaster moderately coriarious, weakly shining to and 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, first gastral tergum with moderately
dense erect setae, longest about equal to MOD; abundant long hairs on margins
of posterior gastral terga,
longest greater than MOD. Body mostly concolorous reddish-orange to
reddish-brown.
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 x. This caste is diagnosed by:
(1) large size (HW = 3.41-3.55 mm), (2) very fine cephalic rugae
covering entire dorsum of head, and (3) in lateral view, lateral lobe of clypeus
massively enlarged with narrow gap (much less than width of antennal scape) between clypeal lobe and frontal carina.
Measurements
- (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 x. Large
species (HW = 3.41-3.55 mm); in full face view, head wider than long (CI =
105.2–114.9), posterior margin weakly concave medially. Longitudinal rugae very fine and dense over entire head; striae on vertex often less abundant and/or less prominent. Interrugal spaces weakly shining to shining. Mandible with six teeth,
dorsal surface coarsely rugose. In side view, lateral lobe of clypeus massively
enlarged with narrow gap (much less than width of antennal scape)
between clypeal lobe and frontal carina, the latter two structures nearly in
contact. Psammophore
moderately well developed.
All mesosomal surfaces with subparallel,
slightly irregular rugae; superior propodeal spines short. Petiolar peduncle about as long as petiole, anteroventral
margin often with blunt to angulate process. In side view, petiolar
node asymmetrical with anterior surface notably shorter than posterior surface,
apex of node rounded. Postpetiole
slightly wider than long. Posterior
surface of petiole and dorsum of postpetiole with
weak to moderately strong, wavy to irregular, transverse rugae;
interrugal spaces weakly to moderately punctate, weakly shining.
Gastral terga
smooth, weakly 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.
Male
Diagnosis. This caste is diagnosed by: (1) hairs on head
(especially posterior to eyes) and dorsum of mesosoma
moderately long and flexuous, longest rarely exceeding 0.5-0.8x MOD, (2) hairs
on mesepimeron long and flexuous, length of many hairs >
0.5x MOD, (3) at least one, usually both mandibles with four teeth, and (4)
superior propodeal spine usually consisting of blunt denticles.
Measurements
- (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. ARGENTINA: Córdoba:
Rt 5 at 3.4
km S Alta Gracia, 1830’, Jan. 23, 2006 (RAJC). Corrientes:
Mercedes, no date (MACN). Entre Ríos: Rt 18 at 7.3 mi SW San Salvado, 220’, Dec.
19, 2005 (CASC; CSC; MCZ; RAJC); La Picada, no date (LACM); Rt
18 at 33.9 mi W Villaguay, 320’, Dec.
20, 2005 (RAJC); Villaguay, no date (MACN; MLPA). Santa Fe: 22 km S Reconquista, 45m, Nov. 15, 2003 (RAJC); 23.2 km NW Reconquista,
Dec. 5, 2005 (CSC); Fives
Lille, no date (MACN). BRAZIL: Rio Grande do Sul:
Porto Alegre, Mar. 24, 1971 (LACM; MCZ; MZUSP); São Leopoldo, no date (MCZ). URUGUAY: Paysandú: Paysandú, Apr. 25, 1961 (LACM). Questionable locales (appear to
be outside of geographic range): ARGENTINA: Buenos
Aires: Monte Hermoso, no date (MLPA).
Etymology. The specific epithet, lobatus (from
Latin, lobat = lobed), refers to the massively
enlarged lateral lobes of the clypeus.
Discussion. Pogonomyrmex lobatus co-occurs
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 rugae often indistinct and cover only part
or most of 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 posteriorly. Pogonomyrmex marcusi is only known from mid- to higher elevation
areas of central
REFERENCES
