Pogonomyrmex laevigatus Santschi 1921
Pogonomyrmex (Ephebomyrmex) laevigatus Santschi: 1921, 97 (worker). Syntypes
examined: 1 worker [MACN], 2 workers [ZSM], #1077, CHILE, Llanqihue:
Cayutué (Dr. Wolffhügel
leg.); Kusnezov, 1949: 301 (male, in key) (MACN
worker here designated LECTOTYPE).
Ephebomyrmex laevigatus Santschi;
Kusnezov: 1960, 354. First
combination in Ephebomyrmex.
Pogonomyrmex laevigatus Santschi; Snelling &
Hunt, 1976: 75. Revived combination in Pogonomyrmex.
Worker
Diagnosis. Within the P. angustus group, the combination of:
(1) dorsum of mesosoma and postpetiole
and posterior face of petiole smooth and shining, (2) body mostly concolorous dark brown-black to black, and (3) juncture of
anterior surface of petiole and peduncle rounded uniquely characterize this
species.
Measurements
- lectotype (n
= 12). HL 1.18 (1.11-1.24); HW 1.06 (0.97-1.13); MOD 0.28
(0.24-0.30); OMD 0.23 (0.20-0.25); SL 0.96 (0.84-0.95); PNW 0.73 (0.66-0.76);
HFL 1.10 (0.99-1.16); ML 1.57 (1.32-1.53); PW 0.28 (0.25-0.31); PPW 0.42
(0.41-0.49). Indices: SI 90.57
(84.07-97.94); CI 89.83 (78.86-92.79); OI 26.42 (23.76-27.84); HFI 103.77
(97.27-113.40).
Description.
Small species (HW = 0.97-1.13 mm), head longer than
wide (CI = 78.86-92.79); posterior margin flat in full-face view. Longitudinal cephalic rugae
coarse, widely spaced, slightly wavy, initiating on frontal lobes, one to few rugae rarely extend to posterior margin; usually 14-18 rugae present between eyes.
Wavy to irregular, often discontinuous rugae
also arc from mandibular margin to frontal lobe and
traverse longitudinally above and below eyes, usually terminating before
vertex; these lateral rugae are weaker than those on
cephalic dorsum. Vertex and posterior
margin of head weakly punctate-granulate, weakly shining
to smooth and shining. Cephalic interrugal spaces smooth, shining. Anterior margin of clypeus
convex; dorsal surface with 6-10 moderately coarse, subparallel
longitudinal rugae; clypeus strongly convex in
lateral view. Mandible with six
teeth; mandibular dorsum strongly striated. MOD ranging from 0.20-0.25x
HL. Eyes in profile situated
anterior to middle of head, OMD = 0.76-0.93x MOD; in full-face view, eyes protruding
well beyond lateral margins of head.
Antennal scapes long (SI = 84.07-97.94),
surpassing vertex by less than length of first funicular segment; scape weakly to moderately granulate-punctate,
often with faint striae, weakly shining; basal flange
poorly developed with carinate margin. Psammophore poorly
developed, consisting of short to medium length hairs scattered over ventral
surface of head.
Mesosomal profile
strongly convex; dorsum of mesosoma and sides of pronotum smooth, shining; longitudinal rugae
on mesospleura and metapleura
wavy to irregular, interrugae weakly to moderately
granulate-punctate, weakly shining. Promesonotal suture
usually present, faint to weakly impressed. Superior propodeal
spines moderately long, narrowing to blunt tip, spine length rarely exceeding
0.7-0.8x distance between bases; inferior propodeal
spines well developed, triangular, narrowing to blunt to acute tip; a keel-like
rugae or crest often connects superior and inferior
spines. Propodeal spiracles narrowly ovate. Legs weakly granulate, weakly shining to smooth
and shining.
Petiolar peduncle about as long as petiole, anteroventral
margin with small, acuminate spine.
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 bluntly angulate; juncture between anterior face of petiole and
peduncle rounded. In dorsal view,
petiole longer than wide, sides subparallel,
narrowing to rounded to bluntly angulate anterior
margin. Dorsum of postpetiole
convex in profile; in dorsal view, widest near posterior margin, narrowing to
anterior margin, maximum width about equal to length; posterior surface and
sides of petiole and dorsum and sides of postpetiole
smooth and shining; dorsum of gaster smooth and
shining.
Erect copperish-brown,
short to long hairs abundant on head, one to few
approaching to slightly exceeding MOD. Moderately abundant subdecumbent to
decumbent hairs on antennal scape; abundant decumbent
to appressed hairs on funicular segments. Legs with moderately
abundant subdecumbent to decumbent setae. Mesosoma with moderately dense, medium to long erect seta, longest
approaching MOD; petiole, postpetiole, gastral terga with moderately
dense erect setae, mostly similar in length, longest notably shorter than MOD. Body mostly a concolorous
blackish to black, mesosoma often a very dark brownish-black.
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) small size (HW = 1.02-1.12 mm), (2) scutellum
and mesoscutellum smooth and shiny, and (3) body
mostly concolorous black.
Measurements
- (n = 2). HL 1.25-1.30; HW 1.02-1.12; MOD 0.26-0.33; OMD 0.20-0.24; SL
0.80-0.91; PNW 0.92-0.93; HFL 1.08-1.12; ML 1.56-1.63; PW 0.32-0.34; PPW
0.51-0.53. Indices: SI 71.43-89.22; CI
78.46-89.60; OI 25.49-29.46; HFI 100.00-105.88.
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.
Small species (HW = 1.02-1.12 mm); in full face view, head elongate (CI
= 78.46-89.60), posterior margin flat. Longitudinal cephalic rugae extending to
near posterior margin, fine and dense medially, density decreasing away from
mid-line, becoming weakly rugoreticulate laterally; vertex
weakly rugoreticulate. Interrugal spaces
weakly to moderately coriarious, weakly shining. Mandible with five to six
teeth, dorsal surface convex, coarsely rugose,
anterior margin flat to slightly convex.
Psammophore poorly developed, consisting of
short to moderately long hairs scattered across ventral side of head.
Mesoscutum, mesoscutellum, dorsum of propodeum
smooth and shining; mesopluera, metapluera,
sides of propodeum longitudinally rugose;
interrugae weakly coriarious,
weakly shining. Superior propodeal spines well developed with blunt tips, inferior propodeal spines consisting of triangular processes, wider
than tall, about 0.5-0.7x length of superior spines. Petiolar peduncle long, anteroventral margin with
small acuminate triangular spine.
In side view, petiolar node
asymmetrical with anterior surface notably shorter than posterior surface, apex
of node subangulate. In dorsal view, postpetiole wider than long. Posterior face of petiole
and dorsum of postpetiole weakly coriarious,
weakly shining to smooth and shining.
Gastral terga
smooth, shining. Most body surfaces with
moderately abundant suberect to erect, yellowish
setae; gaster with fewer setae. Entire body blackish; legs, posterior gastral
terga often with brownish infusion.
Male
Diagnosis. This caste is diagnosed by: (1)
Measurements
- (n = 12). HL ;
HW ; MOD ;
OMD; SL
;
Additional material examined. ARGENTINA: Río Negro: Tronador, no date (MACN); San Carlos de Bariloche, Feb. 8, 1964 (MZUSP).
Neuquén: Hua-Hum, no date (MHNG). CHILE: Araucanía (Cautin): Pucón, Volcan
Villarica, >1000m, Dec.
3, 1989 (LACM). Los Lagos (Llanquihue):
Cayutué, no date (MACN); Petrohue,
Mar. 1922 (MLPA). Maule (Curicó): Cajon de Rio Claro, SE Los Queñes,
1000m, Oct. 9, 1966 (CASC).
*The primary administrative
division in
Etymology. The specific epithet, laevigatus (from Latin, laevigatus = smooth, glossy), is
derived from the smooth, shiny surface over most of the body of this species.
Discussion.
Pogonomyrmex laevigatus co-occurs
with P. angustus
and P. odoratus. Pogonomyrmex laevigatus can be distinguished from P. angustus
based on the following character: dorsum of mesosoma
and posterior face of petiole smooth and shining (both structures strongly
granulate in P. angustus). In his key, Kusnezov
(1951) separated P. laevigatus from P. odoratus
based on: (1) body mostly concolorous blackish to
black (body orangish-brown with the gaster slightly darker in P. odoratus), and (2) shape of the
juncture between the anterior surface of petiole and peduncle (rounded in P. laevigatus,
angulate in P. odoratus). Kusnezov (1949, 1951) also indicated that
longitudinal cephalic rugae were coarser in P. laevigatus than in P.
odoratus, but I did not discern this difference.
Pogonomyrmex laevigatus is
distinguished from other congeners by the poorly developed psammophore
and the smooth and shiny dorsum of the mesosoma. All other congeners have a well developed psammophore and/or the dorsum of the mesosoma
is rugose.
REFERENCES