Pogonomyrmex marcusi Kusnezov 1951
Pogonomyrmex marcusi Kusnezov,
1951: 260, fig. 13a (worker, diagnosis in key). Syntypes
examined: 3 workers [LACM], 3 workers [MZUSP], 16 workers [USNM], BOLIVIA, Cochabamba:
Cochabamba (H. Marcus leg. 19 December 1945 & 4 May 1946). Kusnezov, 1954: 82, figs. 1-4 (queen, male); Marcus, 1953:
43, figs. 33-41 (larvae); Wheeler & Wheeler, 1960: 3 (redescription
of larvae). See also Marcus and Marcus, 1951: 117, figs. 8-11; Marcus, 1953:
43, figs. 30-32 (USNM worker here designated LECTOTYPE).
Worker
Diagnosis. Within the P. coarctatus-group, the combination of:
(1) longitudinal rugae covering most of head, areas
lacking rugae shining to strongly shining, (2) in
side view, lateral lobe of clypeus slightly enlarged, (3) interrugal
spaces on mesosoma smooth, strongly shining, (4) inferior
propodeal spines wider than long, apex bluntly angulate to acute, and (5) bicolored,
head reddish-orange, first gastral tergum reddish-brown, rest of body reddish-orange to
reddish-black uniquely characterize this species.
Measurements
- lectotype (n
= 4 plus 8 paralectotypes). HL 2.00
(1.88-2.24); HW 2.20 (1.91-2.33); MOD 0.43 (0.38-0.44); OMD 0.40 (0.39-0.48);
SL 1.37 (1.10-1.55); PNW 1.14 (1.14-1.36); HFL 1.83 (1.69-2.15); ML 2.20 (2.24-2.75);
PW 0.45 (0.44-0.53); PPW 0.59 (0.59-0.69). Indices: SI 62.27 (57.59-70.92); CI 110.00
(100.000-108.33); OI 19.55 (18.03-20.95); HFI 83.18 (84.98-95.13).
Description. Monomorphic, head
quadrate to wider than long (CI = 100.00-110.00), widest just posterior to eye,
posterior margin flat to weakly concave in full-face view. Longitudinal cephalic rugae
very fine and dense, usually only covering part of head, width of rugae and interrugae similar; in
full-face view median rugae not diverging toward
posterior corners of head. Vertex smooth, strongly shining. Cephalic interrugal
spaces and most of dorsum of head strongly shining. Anterior margin of clypeus
flat to weakly concave; dorsal surface with several moderately coarse subparallel longitudinal, oblique, or arc-shaped rugae. In
side view, lateral lobe of clypeus usually weakly enlarged and elevated. 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 0.18–0.22x HL. Eyes in profile situated anterior to middle
of head, OMD = 0.88–1.18x MOD. Antennal scapes short (SI = 57.59-70.92), extending beyond posterior
margin of eye by less than length of first two funicular segments. Antennal scapes
smooth and 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, slightly
wavy to irregular, widely spaced rugae. In dorsal view, humeral portion of pronotum weakly rounded to knoblike. Dorsum of promesonotum with longitudinal rugae
that diverge anteriorly toward humeral angles;
transverse rugae on anterior face of pronotum continue obliquely or ventrally on pronotal sides; rugae on mesopleura angle to posterior or posterodorsally. Superior propodeal
spines long, acuminate, connected by well-defined keel; spine length 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 bluntly angulate to
acute. Propodeal spiracles narrowly ovate. Interrugal spaces
on mesosoma smooth, strongly shining. Legs weakly granulate, weakly shining to
smooth and strongly shining.
Petiolar
peduncle about 0.7x as long as petiole, anteroventral margin with broadly rounded 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, sides subparallel, slightly wider near middle,
narrowing to spatulate anterior margin. Sides and posterior surface of petiole with
coarse, wavy to irregular transverse, oblique, or longitudinal rugae. Dorsum of postpetiole convex in profile;
in dorsal view, widest near posterior margin, narrowing to anterior margin,
maximum width about equal to length.
Regular to wavy, weak to moderately coarse transverse rugae on dorsum of postpetiole,
sometimes weakening or lacking near anterior margin; interrugal
spaces on posterior face of petiole and dorsum of postpetiole
smooth to moderately granulate, weakly shining to shining. Dorsum of gaster smooth and strongly shining.
Erect white to yellowish pilosity sparsely to moderately abundant on head, mostly
similar in length and arising from foveae; longest hairs not exceeding MOD, few
exceeding 0.5x MOD. Moderately
abundant suberect pilosity
on scape; abundant decumbent hairs on funicular
segments. Legs
with moderately abundant suberect to decumbent setae. Mesosoma with
moderately dense erect setae that are mostly similar in length, longest approaching
MOD; petiole, postpetiole, first gastral
tergum with moderately dense erect setae that are
mostly similar in length, longest notably shorter than MOD; long hairs on
margins of posterior gastral terga
often longer than MOD. Head reddish-orange,
first gastral tergum
reddish-brown; rest of body reddish-orange to reddish-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 xx. This caste is diagnosed by:
(1) smaller size (HW = 2.91 mm), (2) moderately
dense, weak longitudinal rugae over most of head, and
(3) inferior propodeal spines well developed, triangular,
apex bluntly angulate to acute.
Measurements - (n = 1). HL 2.74; HW 2.91; MOD 0.56; OMD 0.63; SL 1.61; PNW 2.06;
HFL 2.43; ML 3.35; PW 0.87; PPW 1.17. Indices:
SI 55.33; CI 106.20; OI 19.24; HFI 83.51.
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) rugae on head moderately strong, subparallel,
with interrugal spaces weakly shining to shining, and
(3) hairs usually yellowish.
Measurements
- (n = 1). HL 1.69;
HW 1.77; MOD 0.54; OMD 0.31; SL 0.45; HFL 2.09; ML 2.97; PW 0.63; PPW 0.78. Indices: SI 25.42;
CI 104.73; OI 30.51; HFI 118.08.
Additional material examined. BOLIVIA: Cochabamba: Cochabamba,
Jan. 24-28, 1954 (LACM; MCZ; USNM; ZSM).
Etymology. Kuznezov named this
species after Dr. Harry Marcus, who apparently collected the syntypes and studied the ecology of this species. Kusnezov described P. marcusi in a key in his revision
of the Pogonomyrmex
of Argentina (Kusnezov,
1951), but he did not describe all three castes
until three years later (Kusnezov,
1954). During
the interim, Marcus completed two studies on ecology of P. marcusi (Marcus, 1953;
Marcus & Marcus, 1951).
Discussion. Pogonomyrmex marcusi is not
known to co-occur near any P. coarctatus-group species, or any other species of Pogonomyrmex. Pogonomyrmex marcusi is easily distinguished from other P. coarctatus-group
species using characters given in the key.
REFERENCES
Marcus, H.
(1953) Estudios mirmecologicos. Folia
Universitaria Cochabamba, 6, 17-68.