Pogonomyrmex angustus Mayr 1870
Pogonomyrmex angustus Mayr, 1870: 970 (worker, in
key). Syntypes examined: 1 worker [NMW], 2 workers [MHNG], #1077,
Pogonomyrmex (Ephebomyrmex) angustus Mayr; Emery, 1921: 48. First combination
in Pogonomyrmex (Ephebomyrmex).
Ephebomyrmex angustus Mayr; Kusnezov,
1960: 353. First combination in Ephebomyrmex.
Pogonomyrmex angustus Mayr; Snelling & Hunt, 1975:
72, fig. 23. Revived combination in Pogonomyrmex.
Worker
Diagnosis. Within the P. angustus
group, the combination of: (1) strongly granulate-punctate
interrugae on head and mesosoma,
(2) posterior face of petiole strongly punctate, and
(3) body concolorous blackish to black, usually with
dark brown legs uniquely characterize this species.
Measurements
- lectotype (n
= 15). HL 1.25 (0.97-1.32); HW 1.12 (0.81-1.16); MOD 0.27
(0.21-0.29); OMD 0.27 (0.18-0.26); SL 0.93 (0.78-1.00); PNW 0.79 (0.59-0.82);
HFL 1.21 (0.89-1.25); ML 1.59 (1.21-1.58); PW 0.31 (0.23-0.34); PPW 0.44
(0.36-0.51). Indices: SI 83.01
(83.04-104.94); CI 89.60 (80.58-91.74); OI 24.11 (21.55-29.63); HFI 108.04
(103.60-118.52).
Description. Small
species (HW = 0.81-1.16 mm), head slightly wider than long to wider than long (CI
= 80.58-91.74); posterior margin flat in full-face view. Longitudinal cephalic rugae coarse, slightly wavy, initiating on frontal lobes
and extending to posterior margin; rugae on lateral
surfaces more irregular, usually weaker than those on cephalic dorsum; vertex rugose. Cephalic interrugal spaces strongly granulate-punctate, dull.
Anterior margin of clypeus convex; dorsal surface with
several moderately coarse, subparallel longitudinal rugae; clypeus strongly convex in lateral view. Mandible with six teeth; mandibular
dorsum strongly striated. MOD ranging from 0.19-0.24x HL. Eyes in profile situated anterior to middle
of head, OMD = 0.73-1.05x MOD; in full-face view, eyes protruding slightly
beyond lateral margins of head. Antennal
scapes long (SI = 83.01-104.94), reaching vertex; scape moderately to strongly granulate-punctate,
often with faint striae, dull; basal flange well
developed with carinate margin. Psammophore poorly
developed, consisting of short to medium length hairs scattered over ventral
surface of head.
Mesosomal profile weakly
convex; dorsum and sides of pronotum and mesonotum with moderately strong irregular rugae; longitudinal rugae on mesospleura and metapleura wavy
to irregular. Dorsum and sides of propodeum usually
lacking rugae; interrugae
strongly granulate-punctate, dull. Promesonotal suture
usually present, faint to weakly impressed in
occasional individuals. Superior propodeal spines moderately long, narrowing to acute tip, length
rarely exceeding 0.7-0.8x distance between bases; inferior propodeal
spines well developed, about the same length as superior spines, triangular, acuminate. Propodeal spiracles narrowly ovate.
Legs smooth and shining to weakly granulate, weakly shining.
Petiolar
peduncle about 0.7x as long as petiole, anteroventral margin with small, acuminate spine. In side view, posterior
face of petiole weakly convex; petiolar node
asymmetrical with anterior surface notably shorter than posterior surface, apex
of node bluntly subangulate to rounded. In dorsal view, petiole longer than wide,
sides subparallel, narrowing to rounded
to subangulate anterior margin; all petiolar surfaces strongly granulate-punctate,
dull, occasionally with few weak rugae. Dorsum of postpetiole convex in profile; in dorsal view, widest near
posterior margin, narrowing to anterior margin, maximum width about the same as
to slightly wider than length; dorsum and sides moderately granulate-punctate, weakly shining. Dorsum of gaster smooth and shining.
Erect and suberect, white to cream colored, medium length hairs
moderately abundant on head, few hairs >0.5x 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 moderate
number of medium length erect to suberect setae, but
few present on propodeum, longest hairs usually about
0.7-0.8x MOD; petiole, postpetiole, gastral terga with sparse medium
length setae, longest notably shorter than MOD. Body mostly concolorous
dark brownish-black to nearly black; antennae, legs
dark brown.
Queen
Diagnosis. As in worker diagnosis, but with
caste-specific morphology of the mesosoma related to
wing-bearing, presence of small ocelli on the head,
and as illustrated in Figure x. This
caste is diagnosed by: (1) small size (HW = 0.99-1.22 mm), (2) mesoscutum and mesoscutellum strongly
granulate-punctate, (3) petiole elongate in dorsal
view, (4) ventral process of postpetiole small, poorly
developed, not bulbous, length greater than height, and (5) body concolorous black to blackish.
Measurements - (n = 11). HL 1.10-1.39; HW 0.99-1.22; MOD 0.26-0.31; OMD 0.18-0.30;
SL 0.82-1.03; PNW 0.71-0.97; HFL 1.06-1.28; ML 1.57-1.87; PW 0.33-0.38; PPW
0.46-0.59. Indices: SI 79.66-87.27; CI
82.58-94.40; OI 22.13-28.44; HFI 99.15-110.09.
Male
Diagnosis. This caste is diagnosed by: (1) small (HW
< 1.15 mm and ML < 2.00 mm), (2) funicular segments with very dense,
short, suberect hairs, and (3) venter
of peduncle has a small acuminate spine.
Measurements
- (n = 6). HL 1.03-1.19; HW 0.88-1.01; MOD 0.35-0.42; OMD 0.11-0.22;
SL 0.28-0.78; HFL 1.11-1.23; ML 1.54-1.71; PW 0.26-0.30; PPW 0.42-0.49. Indices: SI 31.82-80.41; CI
84.62-92.59; OI 36.08-43.18; HFI 117.00-126.14.
Additional
material examined. ARGENTINA: Chubut: El Bolson, Feb. 12, 1949 (LACM); Lago Menéndez, no date (USNM). Neuquén:
Brazo Huemul Nahual Huapi Lago, 2840’, Jan. 26,
2011 (RAJC); Río Caleufu, 20 mi W Collon-Curá,
Mar. 9-14, 1980 (CASC); Hua-Hum, Jan. 26, 1949 (CASC;
LACM), Quilaquina, no date (MACN); San Martín de los Andes,
800m, Jan 8, 1995 (MCZ; MLPA); Pucará, no date (MZUSP). Río Negro: Cerro Lopez, 1003m, Jan. 2005 (RAJC); 11.4 km E Llao Llao,
760m, Nov. 16, 1966 (CASC); 5.6 km N Río Foyel, 920m,
Nov. 18, 1966 (CASC); Victoria Nahuel Huapi, Jul. 19,
1971 (MZUSP). CHILE: Araucanía (Malleco)*: Cerro de Naguelbuta, Angol 620m & 650m, Oct. 12, 1931 (MCZ). Araucanía
(Cautín):
10 km E Pucon, Jan. 12, 1951 (CASC; LACM); Temuco, no
date (MCZ); 20 km E Temuco, Jan. 8, 1951 (CASC; USNM); 12.3 km N Loncoche, 280m, Nov. 16, 1966 (CASC; LACM). Biobío:
Chillan Cordillera, Mar. 12, 2005 (CASC). Biobío
(Arauco): Cordillera Nahuelbuta, 20 km W Caramávida,
750m, Jan. 31, 1967 (CASC). Biobío (Ñuble): 50 km E San
Carlos, Dec. 26, 1950 (MCZ). Los Lagos (Osorno): Pucatrihue,
0m, Feb. 4, 1967 (CASC). Los Lagos (Valdivia): no loc., no date (MCZ;
MLPA; NMW). Maule (Maule): Cuyurranquill, 400m, Jan.
23-31, 1981 (USNM). Metropolitan (Santiago):
Cuesta de la Dormida, 1000m, Nov. 1, 1966 (CASC; LACM); Cerro el Roble, ca. 2000m, Oct. 22, 1972 (LACM). O’Higgins (Colchagua):
3 km N Callejones, Jan. 22, 1967 (CASC). Valparaíso (Aconagua): 90 km S Illapel,
Nov. 28, 1950 (CASC). Valparaíso (Valparaíso) Río Marga Marga, Los
Perales, 330m, Oct. 13, 1966 (CASC). Prov. Unknown: no loc., no date (USNM).
*The primary administrative
division in
Etymology.
The name of this species, angustus (from Latin, angustus = narrow, small), is
derived from the narrow body, as discussed in the description by Mayr.
Discussion. Pogonomyrmex angustus co-occurs
with both P. laevigatus
and P. odoratus. Pogonomyrmex angustus can be distinguished from these two species
based on the following characters: (1) dorsum of mesosoma
and posterior face of petiole strongly granulate-punctate. In both P.
laevigatus and P. odoratus,
the dorsum of mesosoma and posterior face of petiole
are smooth and shining.
Pogonomyrmex angustus is
distinguished from other congeners by the poorly developed psammophore
and the strongly granulate dorsum of the mesosoma and
posterior face of the petiole. All other
congeners have a well developed psammophore and/or
the dorsum of the mesosoma and posterior face of the
petiole is not granulate.
Mayr (1870) described the worker of P. angustus in
a key with no additional information, and he later described the worker Mayr (1887), listing the type locality
as “Valdivia in Chile”. As noted by Kusnezov (1949), this vague locality does
not indicate if the type locality was in the city or province of Valdivia.
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