Pogonomyrmex stefani Lattke 2006
Pogonomyrmex stefani Lattke, 2006: 53, figs. 1-4 (worker, male). Types examined: 1 worker paratype (MCZ), VENEZUELA, Bolívar: Fundo San
Rafael, Río Víllacoa, 165m, 6o25’N, 67o01’W, 6.XII.2004
(J.E. Lattke leg. #2964).
Worker
Diagnosis. Within the P. sylvestris-group, the combination of: (1) six mandibular teeth,
(2) eyes with hairs between ommatidia, (3) in lateral view, anterior margin of
postpetiole not meeting helcium at a smooth continuous angle, (4) procoxa
transversely striate in lateral view, and (5) femur and tibiae smooth to weakly
coriarious, weakly to moderately shining uniquely characterize this species.
Measurements
- (n = 1 paratype). HL 1.29; HW 1.29; MOD 0.23; OMD 0.25; SL
1.02; PNW 0.89; HFL 1.38; ML 1.39; PW 0.29; PPW 0.42. Indices: SI 79.07; CI 100.00; OI 17.83; HFI
106.98. See also Lattke (2006).
Description. Head quadrate (CI = 100.00), broadest just
posterior to eye; posterior margin slightly concave. Longitudinal cephalic rugae coarse, wavy to
irregular medially, becoming more irregular to rugoreticulate laterally. Cephalic interrugal spaces
deeply incised, moderately granulate-punctate, weakly shining. Anterior margin of clypeus weakly
convex; dorsum with several subparallel longitudinal rugae. Mandible with six teeth; mandibular dorsum
coarsely striated. Up to several
moderately long, curved, bristle-like, yellowish hairs project from anterior
edge of clypeus. Eyes small, MOD = 0.18x
HL. Eyes in profile situated anterior to
middle of head, OMD = 1.09x MOD; several hairs project from between
ommatidia. Antennal scapes long (SI =
79.07), surpassing vertex by less than width of basal funicular segment; entire
scape with moderately strong longitudinal striae, dull to weakly shining. Basal flange of scape well developed with
carinate margin. Psammophore poorly
developed, consisting of numerous medium to long hairs scattered across ventral
side of head.
Mesosomal
profile strongly convex; all mesosomal surfaces with prominent rugae. Promesonotum
with irregular longitudinal rugae medially, dorsum of propodeum with irregular
transverse rugae, all other mesosomal surfaces rugoreticulate to vermiculate. Propodeum with long acuminate superior propodeal
spines, bases connected by poorly defined keel, spine length greater than
distance between bases. Inferior propodeal spines well-developed with a broad triangular
base, length less than 0.5x that of superior spines. Propodeal spiracles
prominent, circular. Interrugal spaces on mesosoma weakly shining. In lateral view, procoxa
with fine subparallel transverse striae.
Legs smooth and shining to weakly coriarious, weakly shining.
Petiolar
peduncle long, about 0.7x length of petiole; anteroventral margin with a long
acuminate spine. In side
view, posterior surface of petiole weakly convex; petiolar node asymmetrical
with anterior surface slightly less than one-half the length of posterior surface,
apex of node forming a bluntly tipped crest or tooth that is elevated above
posterior surface; lateral and posterior surfaces with wavy to irregular
longitudinal rugae to slightly rugoreticulate on posterior surface. In dorsal view, petiolar
node elongate (length usually > 1.90x width), sides subparallel, anterior
portion narrowing to a subangulate tip; interrugal spaces with weaker secondary
rugae, weakly shining. Dorsum of
postpetiole convex in profile, anterior margin truncated, not narrowing
gradually to meet helcium; robust in dorsal view, trapezoidal, widest at or
near posterior margin, narrowing to rounded anterior margin; lateral margins
wider ventrally at posterior margin; dorsum smooth and strongly shining to very
weakly coriarious, shining. First gastral tergum smooth and strongly shining to very weakly
coriarious, shining.
Long, erect, yellowish to golden hairs abundant on head; medium to long hairs abundant on mesosoma, petiole, postpetiole, and dorsum of gaster; longest hairs on head and mesosoma > MOD. Scape with abundant medium to long suberect hairs; abundant decumbent hairs on funicular segments. Legs with moderately abundant, long, suberect to semidecumbent setae. Head, antennae, mesosoma, petiole, and postpetiole dark brown; mandibles, legs, and gaster brown.
Queen. Unknown.
Male
Diagnosis. See Lattke (2006) for description, but note
that males are unknown for P.
striatinodis and P. sylvestris.
Measurements
- (n = 1). HL 1.06; HW 1.04; MOD
0.44; OMD * ;
SL 0.25; HFL *; ML 1.87; PW *; PPW *. Indices: SI 0.24; CI
0.98; OI 0.43; HFI *. * = not available; measurements from
Lattke (2006).
Additional
material. VENEZUELA: Bolívar; c.
Amarawai Tepui, 470m, May 2, 1986 (5o55’N, 62o15’W)(not examined).
Etymology: This
species was named in honor of Dr. Stefan Schödl, who occupied the post of
Curator of Hymenoptera in the Naturhistoriches Museum of Vienna until his death
in April 2005.
Discussion. Pogonomyrmex
stefani is the only P. sylvestris-group species known to occur in lowland mesic
forests. The prominent transverse striae
on the procoxa separate P. stefani from both P.
striatinodis (procoxa sometimes very weakly striate, mostly smooth and
shining) and P. sylvestris (procoxa
imbricate, dull).
Pogonomyrmex naegelii is the
only congener that might occur sympatrically with P. stefani, but the former species would occur
in open, drier habitats than those occupied P.
stefani. Pogonomyrmex stefani is distinguished from
P. naegelii by: (1) hairs that project from between ommatidia, (2) an
elongate, triangular postpetiole, and (3) in lateral view, petiole is flattened
to slightly convex with a crest or tooth on anterior margin that is elevated
above the posterior face. Pogonomyrmex naegelii lacks hairs
between ommatidia, the postpetiole is nearly globular with width and length similar, and in lateral view, the petiole is convex and lacks
a crest or tooth on anterior margin.
BIOLOGY
Very little is known about the
biology of the three P. sylvestris-group
species. All three species are discussed
together because they likely share a similar biology. Stray foragers comprise most collections for
these three species. Few nests have been
located: nests of P. stefani
consisted of a small exposed entrance (Lattke, 2006), one nest of P. sylvestris was in a rotten log (Lattke, 2006), and nests of P. striatinodis
are unknown. Diet and the sexual castes are unknown (except for the
male of P. stefani)
for all three species.
All three
species are only known to occur in northern South America (Venezuela, Colombia,
and Ecuador), and they are part of a small group of South American congeners that
inhabit mesophilic forest habitats (the others are the Patagonian species P. angustus,
P. laevigatus, P. odoratus, and probably P.
chubutensis). Pogonomyrmex sylvestris and P. striatinodis are mid-elevation
species; P. sylvestris has been collected only in premontane cloud forest
habitats of
The P. sylvestris-group
comprises the basal species in the genus, and P. mayri is the sister species to this group (Moreau et al., in prep.).
Consequently, obtaining information on the biology of P. sylvestris-group species (including
diet, colony size and structure, phenotypes of males and especially queens) would
facilitate understanding the early evolution of the genus; queens would be
especially interesting given that P.
mayri has ergatoid queens. It is
predicted that biology of these species is similar to that of P. mayri, which suggests that colonies
are small (no more than several hundred workers) and that their diet mostly consists
of dead arthropods and plant parts, but relatively few seeds (see Kugler, 1978; 1984; Kugler & Hincapie, 1983).
REFERENCES