J. HYM. RES.
2(1), 1993 pp. 117-168
Systematic studies on Pseudomyrmex acacia-ants
(Hymenoptera: Formicidae: Pseudomyrmecinae)
PHILIP S. WARD
Department of Entomology, University of California, Davis, CA 956 1 6
Abstract. The obligate acacia-ants ( Pseudomyrmex ferrugineus group) are well known as defensive inhabitants
of swollen-thorn acacias in the northern Neotropics. A taxonomic revision of these ants leads to the recognition of
ten species: P. ferrugineus (F. Smith), P. flavicornis (F. Smith), P. janzeni, sp. nov., P. mixtecus, sp. nov., P.
nigrocinctus (Emery), P. particeps, sp. nov., P. peperi (Forel), P. satanicus (Wheeler), P. spinicola (Emery), and
P. veneficus (Wheeler). The following new synonymy is proposed: P. nigrocinctus = P. alfari (Forel) = P. bicinctus
(Santschi) = P. peltatus (Menozzi); P. spinicola = P. atrox (Forel) = P. gaigei (Forel) = P. infernalis (Wheeler) =
P. scelerosus (Wheeler). Diagnostic descriptions and taxonomic comments are also provided for ten other unrelated
species of Pseudomyrmex which have become secondarily associated with swollen-thorn acacias either as obligate
and, in at least one case, parasitic occupants (P. nigropilosus (Emery), P. simulans Kempf and P. subtilissimus
(Emery); P. reconditus, sp. nov., may also belong in this category) or as facultative inhabitants ( P. boopis (Roger),
P. gracilis (Fabricius), P. hesperius, sp. nov., P. ita (Forel), stat. nov., P. kuenckeli (Emery) and P. opaciceps, sp.
nov.). A cladistic analysis of the P. ferrugineus group yields the following result which appears to be fairly robust
insofar as there is congruence among the trees derived from worker-, queen-, and male-based character sets:
((nigrocinctus + particeps) + (peperi + ((satanicus + spinicola) + ferrugineus complex))). The "ferrugineus
complex" comprises five species whose phylogenetic relationships are not fully clarified. The composite data set
(47 characters from all three castes) supports the following partial resolution: (ferrugineus + janzeni + (flavicornis
+ (mixtecus + veneficus))). The cladogram of the P. ferrugineus group indicates that speciation in the group has
occurred primarily as a consequence of geographical isolation, and that the ants and their host acacias have
experienced diffuse coevolution rather than strict cospeciation.
INTRODUCTION men ts have appeared in the ecological literature. In
this paper I present a taxonomic revision of the
Pseudomyrmex ferrugineus (F. Smith) and re- obligate acacia-ants (Pseudomyrmex ferrugineus
lated species of ants form a well-defined mono- group) and an assessment of their phylogenetic
phyletic group, the members of which nest exclu- relationships. I also attempt to clarify the identities
sively in the hollow, swollen thorns of several New of other, unrelated species of Pseudomyrmex which
World Acacia species. Because of their aggressive have become secondarily associated with swollen-
behavior and predictable occurrence on the acacias, thorn acacias.
these ants have received considerable attention The earlier taxonomic literature on acacia-ants
from tropical biologists (Belt 1874; Safford 1922; is scattered in more than a dozen papers containing
Skwarral934a,1934b; Wheeler 1942; Janzen 1966, descriptions of various species, subspecies, and
1973). The landmark studies of Janzen (1966, "varieties". Two of the more comprehensive treat-
1967b) provided strong experimental evidence of ments are those of Emery (1890) and Wheeler
the mutualistic nature of the Pseudomyrmex/Aca- (1942). In presenting the results of his ecological
cia association, and the relationship between the studies Janzen (1966, 1967b, 1973) summarized
two organisms is often cited in discussions of his understanding of acacia-ant taxonomy. Ward
coevolved mutualisms (e.g. Gilbert 1983; Beattie (1989) provided a brief diagnosis of the P.
1985; Futuyma 1986). At the same time, the ferrugineus group, together with taxonomic and
systematics of the acacia-ants has been neglected, nomenclatural notes on the commoner species,
with the result that misidentifications and misstate-
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JOURNAL OF HYMENOPTERA RESEARCH
MATERIALS AND METHODS
COLLECTIONS
Material for the present study was examined in
the following collections:
AMNH American Museum of Natural History, New
York, NY, USA
ANSP Academy of Natural Sciences, Philadel-
phia, PA, USA
BMNH The Natural History Museum, London,
U.K.
CASC California Academy of Sciences, SanFran-
cisco, CA, USA
CHAH C.H.A. Hespenheide Collection, Univer-
sity of California at Los Angeles, C A, USA
CISC California Insect Survey, University of
California at Berkeley, CA, USA
CUIC Cornell University Insect Collection,
Ithaca, NY, USA
EBCC Estacion de Biologia Chamela, Jalisco,
Mexico
FFIC Fernando Fernandez Collection, Santa Fe
de Bogota, Colombia
GBFM Graham B. Fairchild Museo de
Invertebrados, Universidad de Panama,
Panama
GCWCG.C. & J. Wheeler Collection, Silver
Springs, FL, USA
INBC Institute Nacional de Biodiversidad (col-
lections previously held in MNCR: Museo
Nacional de Costa Rica), San Jose, Costa
Rica
INKS Illinois Natural History Survey Insect Col-
lection, Champaign, IL, USA
JTLC J.T. Longino Collection, Evergreen State
College, Olympia, WA, USA
KSUC Kansas State University Insect Collection,
Manhattan, KS, USA
LACM Natural History Museum of Los Angeles
County, Los Angeles, CA, USA
MCSN Museo Civico di Storia Naturale, Genoa,
Italy
MCZC Museum of Comparative Zoology, Harvard
University, Cambridge, MA, USA
MHNG Museum d'Histoire Naturelle, Geneva,
Switzerland
MNHN Museum National d'Histoire Naturelle,
Paris, France
MZSP Museo de Zoologia da Universidade de
Sao Paulo, Brazil
NHMB Naturhistorisches Museum, Basel, Swit-
zerland
NHMV Naturhistorisches Museum, Vienna, Aus-
tria
PSWC P.S. Ward Collection, University of Cali-
fornia at Davis, CA, USA
SEMC Snow Entomological Museum, University
of Kansas, Lawrence, KS, USA
UCDC Bohart Museum of Entomology, Univer-
sity of California at Davis, CA, USA
UCRC UCR Entomological Collection, Univer-
sity of California at Riverside, CA, USA
USNM National Museum of Natural History,
Washington, DC, USA
WPMC W.P. MacKay Collection, El Paso, TX,
USA
ZMHB Zoologisches Museum, Museum fur
Naturkunde der Humboldt-Universitat,
Berlin, Germany
ZMUC Zoologisk Museum, University of
Copenhagen, Denmark
ZMUH Zoologisches Institut und Zoologisches
Museum der Universitat Hamburg, Ger-
many
ZSMC Zoologische Staatssammlung, Munich,
Germany
Special mention should be made of the very
large and important series of Pseudomyrmex col-
lected by D.H. Janzen from 1963 to 1974 and now
housed in the Natural History Museum of Los
Angeles County (LACM). The Janzen material
includes a large number of pinned specimens (usu-
ally glued to the side of the pin rather than point-
mounted) and an extensive alcohol collection (partly
overlapping with the pinned series but including
additional accessions). Janzen's field notes per-
taining to the collection of these ants have also been
deposited in LACM. Obligate acacia-ants (P.
ferruginem group) constitute the bulk of the col-
lected material. They occur as long nest series from
throughout Central America, with very useful queen-
male-worker associations, making this material of
inestimable value to the current revision.
VOLUME 2, NUMBER 1, 1993
119
When the Janzen collection was received at
LACM in 1984 most specimens had only code
numbers associated with them among the pinned
specimens a single individual per nest series typi-
cally contained a code number, with the remaining
specimens being unlabelled and in some instances
difficulties arose in retrieving full data for coded
specimens from Janzen' s field notes. In other cases
the field notes contradicted the apparent identity or
composition of a nest series. This latter problem
applied mainly to pinned specimens; the alcohol
material appeared to be reliably labelled or coded,
i.e. the contents of the vials agreed with the field
notes. Thanks to the efforts of Roy Snelling and
Jack Longino, who incorporated the Janzen collec-
tion into the LACM, many of these discrepancies or
uncertainties were resolved, but there remains a
residue of "problem material" for which collection
data are lacking or ambiguous. Among the pinned
specimens this comprises twelve drawers in the
LACM collection which have been specifically set
aside from the main collection. None of this prob-
lematical material has been cited in the present
study, but I have examined it and determined that
no additional species are represented there. Al-
though omission of this material means the poten-
tial loss of some locality data, I have examined the
entire alcohol collection and point-mounted repre-
sentative samples so that geographic coverage re-
mains extensive. The main pinned series of LACM
acacia-ants, i.e. that for which accurate data labels
are available, comprises 30 drawers and approxi-
mately 20,000 specimens, the great majority of
which were collected by Janzen.
METRIC MEASUREMENTS AND INDICES
All measurements were made under a Wild
microscope at SOX power, using an orthogonal pair
of Nikon micrometers wired to a digital readout.
Measurement conventions follow those described
in Ward (1985, 1989). Note that a full-face or
dorsal view of the head involves positioning the
posterior margin and the anterolateral margins
(above the mandibular insertions) so that they lie in
the same plane of view.
The following measurements and indices are
cited in this study (the first six measurements are
taken with the head in a full-face, dorsal view):
HW Head width: maximum width of head, in-
cluding the eyes.
VW Vertex width: width of the posterior portion
of the head (vertex), measured along a line
drawn through the lateral ocelli.
HL Head length: midline length of head proper,
from the anterior clypeal margin to the mid-
point of a line drawn across the "occipital"
(i.e. posterior) margin.
EL Eye length: length of compound eye; note
that this is measured with the head in full
face, dorsal view, unlike EW(below).
OD Ocellar distance: distance from the middle of
the median ocellus to the midpoint of a line
drawn between the lateral ocelli.
OOD Oculo-ocellar distance: distance from the
middle of the median ocellus to the midpoint
of a line drawn across the posterior margins
of the compound eyes (this distance is nega-
tive in value if the posterior margin of the
compound eye exceeds the median ocellus).
MFC Minimum frontal carinal distance: minimum
distance between the frontal carinae, poste-
rior to their fusion with, or approximation to,
the antennal sclerites.
ASD Antennal sclerite distance: maximum dis-
tance between the lateral margins of the me-
dian lobes of the antennal sclerites, measured
in full-face, dorsal view of the head.
ASO Antennal sclerite distance, outer margins:
maximum distance between the outer, lateral
margins of the antennal sclerites.
CLW Width of median clypeal lobe, measured
between the anterolateral angles (in
Pseudomyrmex satanicus and P. spinicola
only; see Figs. 10, 11).
MD4, MD5, MD8, MD9 A series of mandibular
measurements (see Ward 1989, figure 2).
MD4: distance along the basal margin of the
mandible from the base to the mesial basal
tooth; MD5 : length of the basal margin ; MD8 :
distance along the masticatory margin from
the apex to the fourth tooth, counting from
the apex; MD9: length of the masticatory
margin.
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JOURNAL OF HYMENOPTERA RESEARCH
EW Eye width: maximum width of compound
eye, measured along its short axis in an
oblique dorsolateral view of the head.
SL Scape length: length of the first antennal
segment, excluding the radicle.
LF1 Length of first funicular segment: maximum
measurable length of the first funicular seg-
ment (pedicel), including its basal articula-
tion in workers and queens but excluding the
basal articulation in males (where it is usu-
ally hidden).
LF2 Length of second funicular segment: maxi-
mum measurable length of the second
funicular segment.
LF3 Length of third funicular segment: maxi-
mum measurable length of the third funicular
segment.
WF2 Width of second funicular segment,
FL Profemur length: length of the profemur,
measured along its long axis in posterior
view (see Ward 1985, figure 3).
FW Profemur width : maximum measurable width
of the profemur, measured from the same
view as FL, at right angles to the line of
measurement of FL.
DPL Diagonal length of the propodeum: length of
the propodeum, measured in lateral view
along a diagonal line drawn from the
"metapleural" lobe to the metanotal groove
(see Ward 1985, figure 2).
BF Length of the basal (=dorsal) face of the
propodeum, measured in lateral view from
the metanotal groove to the point on the
surface of the propodeum which is maxi-
mally distant from the diagonal propodeal
line.
DF Length of the declivitous face of the
propodeum, measured in lateral view from
the "metapleural" lobe to the point on the
surface of the propodeum which is maxi-
mally distant from the diagonal propodeal
line.
MP Depth of metanotal groove ("mesopropodeal
impression"), measured in lateral view from
the bottom of the metanotal groove to a line
drawn across the dorsal surface of the
mesonotum and propodeum.
PL Petiole length: length of the petiole, mea-
sured in lateral view from the lateral flanges
of the anterior peduncle to the posterior mar-
gin of the petiole (see Ward 1985, figure 4).
PND Petiolar node distance: distance from the
lateral flanges of the anterior petiolar pe-
duncle to the maximum height of the node,
measured from the same view as PL and
along the same line of measurement (see
Ward 1985, figure 4).
PH Petiole height: maximum height of the peti-
ole, measured in lateral view at right angles
to PL, but excluding the anteroventral pro-
cess.
PPL Postpetiole length: length of the postpetiole,
measured in lateral view, from the anterior
peduncle (of the postpetiole) to the point of
contact with the fourth abdominal tergum,
excluding the pretergite (see Ward 1985,
figure 4).
DPW Dorsal petiolar width: maximum width of the
petiole, measured in dorsal view.
MPWMinimum petiolar width: minimum width of
the petiole,measured in dorsal view, anterior
to DPW.
PPW Dorsal postpetiolar width: maximum width
of the postpetiole, measure in dorsal view.
LHT Length of metatibia: maximum measurable
length of metatibia, excluding the proximal
part of the articulation which is received into
the distal end of the metafemur (see Ward
1989, figure 5).
CI Cephalic index: HW/HL
OI Ocular index: EW/EL
REL Relative eye length: EL/HL
REL2Relative eye length, using HW: EL/HW
OOI Oculo-ocellar index: OOD/OD
VI Vertex width index: VW/HW
FCI Frontal carinal index: MFC/HW
FCI2 Frontal carinal index, using ASD: MFC/ASD
ASI Antennal sclerite index: ASD/ASO
SI Scape index: SL/HW
SI2 Scape index, using EL: SL/EL
FLI Funicular length index: (LF2 + LF3)/WF2
FI Profemur index: FW/FL
PDI Propodeal index: BF/DF
MPI Metanotal index: MP/HW
NI Petiole node index: PND/PL
VOLUME 2, NUMBER 1, 1993
121
PLI Petiole length index: PH/PL
PLI2 Petiole length index, using PPL: PPL/PL
PWI Petiole width index: DPW/PL
PWI2 Petiole width index, using PPW: DPW/PPW
PWI3 Petiole width index, using MPW: MPW/
DPW
PWI4 Petiole width index, using LHT: DPW/
LHT
PPWI Postpetiole width index: PPW/PPL
Other Conventions
Other terminology follows the usage in Ward
(1989). Note that descriptions of surface sculpture
and integument reflectance apply to observations
made under soft light, with an opaque (Mylar) filter
placed between the specimens and source of illumi-
nation. Palp formula refers to the number of max-
illary palp segments followed by the number of
labial palp segments; 5p4,3 indicates a condition
intermediate between 5,3 and 4,3, i.e. partial fusion
of the fourth and fifth maxillary palp segments.
Listing of synonymy under each species is re-
stricted to citation of the original descriptions (with
full reference given for all previously proposed
junior synonyms) and new nomenclatural combi-
nations. For ecologists a more useful summary of
name usage is offered in Table 1 , which indicates
the correspondences between the names appearing
in the biological literature on acacia-ants and the
currently valid scientific names. The reader will
appreciate that there has been considerable
misidentification of these ants.
In the lists of material examined of each species,
I have cited only locality and collector ("c.u."
signifies collector unknown), with the source col-
lections listed together at the beginning. Additional
locality information is sometimes provided in square
brackets, to facilitate location of the collecting site.
Considerable effort was expended to determine the
coordinates (latitude and longitude) of each collect-
ing site, and this was then used in conjunction with
the public domain software program Versamap
(version 1.20) to plot the distributions of each
species (Figs. 67-72).
Cladistic Analysis
A set of 47 characters, representing the most
discrete or quantifiable differences among species
or groups of species in the P. ferrugineus group,
was used for phylogenetic analysis. Twenty of
these characters were worker-based (11 of these
manifested the same conditions in queens), 8 were
queen-based, and 19 were taken from male mor-
phology, primarily male genitalia. The characters
and character states are as follows:
1. Worker, median clypeal lobe (0) laterally
rounded or subangulate, ( 1 ) laterally with sharp
angles or teeth (Figs. 10, 11).
2. Worker and queen, frontal carinae (0) rela-
tively well separated, median lobes of anten-
nalsclerites less exposed (Figs. 12-19, 32), (1)
closely adjacent and median lobes of antennal
sclerites more exposed (Figs. 10, 11, 32).
3. Worker and queen, palp formula (0) 5,3, (1)
4,3.
4. Worker, head (0) broader, relative to HL, DPL
and PL, (1) narrower; see regressions of HL,
DPL and PL on HW (Figs. 36-38).
5. Worker, scape (0) short, relative to HL, (1)
longer; regression of SL on HL lying above
that of other species.
6. Worker, conspicuous pit-like impression on
midline of head (0) absent, (1) present.
7 . Worker, petiole (0) short relative to postpetiole,
PLI2 0.77, (1) longer relative to postpetiole,
PLI2 < 0.77.
8. Worker and queen, petiole (0) without a well
differentiated anterior peduncle, i.e. weakly
constricted in dorsal view and with little or no
inflection of the anterior face of the petiole in
lateral profile (Figs. 22, 23), (1) with a well
differentiated peduncle (Figs. 20, 21, 24-29).
9. Worker and queen, petiole, dorsal view,
angulate posterolateral corners (0) absent, (1)
moderately developed, preceded by convex or
sinuate sides (e.g. Figs, 20, 27), (2) very promi-
nent, preceded by more or less straight sides
(Fig. 24).
10. Worker and queen, petiole (0) shorter and
higher, worker PLI 0.71, queen PLI 0.64,
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JOURNAL OF HYMENOPTERA RESEARCH
(1) more slender, worker PLI < 0.72, queen
PLI < 0.64.
11. Worker, DPW relative to HW (0) narrow, (1)
broader, (2) very broad; see regression of
DPW on HW (Fig. 41).
12. Worker, plot of PWI3 by HW lying in (0)
upper left ( 1 ) lower right (2) lower left region,
of Fig. 39.
1 3 . Worker and queen, plot of PWI4 by HW lying
in (0) center and lower right (1) upper left (3)
lower left region, of Fig. 40.
14. Worker, postpetiole (0) broad, PPWI > 1.30,
(1) narrow, PPWI 1.00-1.30.
1 5 . Worker, metatibia (0) short, relative to HL, ( 1 )
relatively long; see regression of LHT on HL
(Fig. 30).
16. Worker and queen, head sculpture (0) densely
punctulate, subopaque to sublucid, at least on
upper third of head, (1) densely punctulate,
opaque, (3) punctulate-coriarious, opaque
(matte).
17. Worker and queen, propodeum, posterolat-
eral portions (0) sublucid, without overlying
rugulo-punctate sculpture, (1) supopaque to
opaque, with rugulo-punctate sculpture.
18. Worker and queen, petiolar node (0) lacking
conspicuous suberect pubescence, (1) with
such pubescence.
19. Worker and queen, standing pilosity on exter-
nal faces of tibiae (0) present, (1) absent.
20. Worker and queen, head and gaster (0) yel-
low- to orange-brown, (1) reddish-brown to
medium or dark brown, (2) very dark brown to
black (excluding mandibles, clypeus and
scape).
21. Queen, size (0) small, HW 0.85, (1) medium
to large, HW 0.85.
22. Queen, head shape, for a given LHT (0) elon-
gate, (1) less elongate, (2) broad (see Fig. 52).
23. Queen, petiole (0) short, relative to HW, PL/
HW < 0.7 1 , ( 1 ) longer, PL/HW 0.71.
24. Queen, petiole (0) short, relative to HL, (1)
longer: see regression of PL on HL (Fig.46).
25. Queen, regression of PH on HW lying in (0)
upper (1) middle (2) lower region, in Fig. 47.
26. Queen, petiole, dorsal view (0) narrow, rela-
tive to HL, (2) broader; regression of DPW on
HL lying above that of other species.
27. Queen, metatibia (0) short, relative to HL,
LHT/HL < 0.62, (1) longer, LHT/HL > 0.66.
28. Queen, metatibia (0) short, relative to HW, (1)
longer; see regression of LHT on HW (Fig.
31).
29. Male, head (0) narrower, CI 0.82-0.94 and
HW < 0.96, (1) broader, CI 0.94 and/or HW
0.96 (regression of HL on HW lying below
that of other species).
30. Male, scape index (SI) (0) 0.22-0.30, (1) 0.29-
0.35, and regression of SL on HW lying above
that of other species.
3 1 . Male, scape length, relative to EL and HL (0)
long, SI2 0.43-0.56, SL/HL 0.22, (1)
shorter, SI2 0.33-0.43, SL/HL 0.21 (and
regression of SL on HL lying below that of
other species).
32. Male, compound eye length, relative to HW
(0) long, REL2 0.56-0.63, (1) shorter, REL2
0.49-0.58, and regression of EL on HW lying
below that of other species.
33. Male, petiole (0) less slender, PLI > 0.45, (1)
more slender, PLI < 0.50, and regressions of
PH and DPW on LHT lying below those of
other species.
34. Male, sternite IX, posterior margin (0) con-
vex, (1) with a moderate concavity, less than
semicircular (Fig. 54), (2) with a deep, semi-
circular concavity (Fig. 55).
35. Male, paramere, lateral view, posterodorsal
extremity (0) rounded, (1) angulate or ex-
panded.
36. Male, paramere, lateral view, posterodorsal
extremity (0) not projecting caudad, (1) pro-
jecting caudad, as in Figs. 56, 57.
37. Male, paramere, lateral view, posterodorsal
extremity (0) not developed as a lobe-like
protrusion, whose mesial face is a saucer-like
concavity, (1) so developed (Figs. 61-66).
38. Male, paramere, lateral view, posterodorsal
extremity (0) well separated from mesiodorsal
lobe, (1) close to mesiodorsal lobe, enclosing
a narrow space between it and the lobe (Figs.
58, 61-66).
39. Male, paramere, digitiform mesiodorsal lobe
(0) absent, ( 1 ) present, slender, directed poste-
VOLUME 2, NUMBER 1, 1993
123
riorly or posterodorsally (Figs. 56-60, 63-65),
(2) present, stubby, directed more or less dor-
sally (Figs. 61, 62).
40. Male, paramere, mesial face of posterodorsal
extremity (0) simple in form, not expanded
mesially, (1) expanded mesially, partly ob-
scuring the mesial dorsoventral ridge in poste-
rior view.
41. Male, aedeagus, posterior margin (0) entire,
not medially pointed, (1) toothed, and medi-
ally pointed.
42. Male, aedeagus, posterior margin (0) bent
posterolaterally, (1) bent anterolaterally, (2)
bent anterolaterally but with the medial point
redirected posteriorly.
43. Male, aedeagus, laterally bent portion of pos-
terior margin (0) continuous with the margin
of the posterodorsal extremity,(l) discontinu-
ous with margin of posterodorsal extremity
(elevated laterally), the two connected by a
gradual slope, (2) discontinuous with margin
of posterodorsal extremity, elevated laterally,
and separated by a trenchant rise (posterior
view) from the posterodorsal extremity.
44. Male, aedeagus, plate-like expansion of
posterodorsal extremity (0) absent, (1) mod-
erately developed, (2) strongly developed.
45. Male, aedeagus, external face (0) without a
large, central elevated area, (1) with a central
elevated area, delimited posteroventrally by a
weak ridge or carina, (2) with a central el-
evated area, delimited posteroventrally by a
strong lamellate carina.
46. Male, aedeagus, external face, afore-men-
tioned carina (if present) (0) well separated
from the toothed posterior margin, ( 1 ) running
close to and more or less parallel with the
toothed posterior margin but separated by a
deep groove, (2) converging posterodorsally
with the toothed posterior margin.
47. Male, aedeagus, postero ventral extremity (0)
broadly rounded, (1) subangulate, (2) angulate
with a tooth-like protrusion.
The data set was analyzed using Farris' Hennig86
program. Characters 12, 13 and 16 were considered
unordered. As an outgroup I chose Pseudomyrmex
fervidus (F. Smith), a Central American species
which shares a number of (mostly worker) features
in common with the P.ferrugineus group: 5,3 palp
formula, similar mandibular dentition, well devel-
oped metanotal groove, abundant pilosity on
mesosoma dorsum, relatively small eyes, and a
similar habitus with respect to size and color. In a
few instances the outgroup species spanned the
phenotypic gap between two discrete states in the
ingroup; it was then coded as unknown for that
character. In addition to seeking the most parsimo-
nious tree for the entire data set (rooted with the
outgroup), I also compared the cladograms based
on three subsets, derived from the worker, queen,
and male characters sets, respectively. For this
second analysis the queen character set included
the eight characters assessed only in queens (2 1 -28)
plus those manifested identically in workers and
queens (2, 3, 8-10, 13, 16-20), for a total of 19
characters.
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JOURNAL OF HYMENOPTERA RESEARCH
7
Figs. 1-9. Pseudomyrmex workers, lateral view of mesonotum, propodeum and petiole, with pilosity shown in
outline; Figs. 4 and 5 include a frontal view of worker head. 1 , P. boopis (Costa Rica); 2, P. ita (Costa Rica); 3, P.
kuenckeli (Costa Rica); 4, P. hesperius (Mexico, paratype); 5, P. opaciceps (Guatemala, paratype); 6, P. gracilis
(Mexico); 7, P. nigropilosus (Costa Rica); 8, P. reconditus (Nicaragua, holotype); 9, P. simulans (Panama).
VOLUME 2, NUMBER 1, 1993
125
h
1 mm
Figs. 10-19. Pseudomyrmex ferrugineus group, workers, full-face dorsal (=frontal) view of head with pilosity
shown in outline (except on mandibles); Fig. 19 includes a lateral view of head. 10, P. satanicus (Panama); 1 1, P.
spinicola (Costa Rica); 12, P. peperi (Guatemala); 13, P. nigrocinctus (Costa Rica); 14, P. particeps (Costa Rica,
holotype); 15, P. mixtecus (Mexico, holotype); 16, P.flavicomis (Nicaragua); 17, P. veneficus (Mexico); 18, P.
ferrugineus (Mexico); 19, P.janzeni (Mexico, holotype).
126
JOURNAL OF HYMENOPTERA RESEARCH
1 mm
Figs. 20-29. Pseudotnyrmex ferrugineus group, workers, dorsal view of petiole paired with lateral view of
mesonotum, propodeum, petiole and, in Fig. 28, postpetiole. Standing pilosity shown in outline. 20, P. satanicus;
21, P. spinicola', 22, P. nigrocinctus', 23, P. particeps', 24, P. peperi; 25, P. flavicornis; 26, P. mixtecus; 27, P.
ferrugineus; 28, P. veneficus', 29, P.janzeni. These are the same individuals illustrated in Figs. 10-19.
VOLUME 2, NUMBER 1 , 1 993
127
30
1.2
workers
-i- spinicola, satanicus
D other species
+
3 1" 1
1.4
queens
-+ spinicola, satanicus
D other species + +
f V*
*
+ + + D
1.3
*
1.1
+H ,*f **** * g
\ +
1
v
/r + ffS^^n
1.2
* + + +4-
+ +++ ++ + tfj a
+ + J.J. + [>.
5
+ D
+ * n
m tflja
=5SEj5i n
i 1.1
+ - ^fl?^
0.9
** &L
f#ftl B o n
+ + rft Jo b ^
qScrSS
a o
1
t^ggi^cB
0.8
EUjjta-fSlrilj
a "3
ftmijfiiflB3t]^^
0.9 -
ff fl
'jSSr'ffJj
aa
0.7
a
0.8 -
D
0.6 -
01 D
.8 1
1.2 1.4
0.7 -
.7 0.9 1.1 1.3
.* / 08
HL
HW
32
0.7 -
workers
+- spinicola, satanicus
D other species
D
33 29
0.28 -
workers
-i- spinicola, northern popns.
X spinicola, southern popns.
D D
D satanicus
a
3 n jl D n D
0.27 -
0.6 -
o r a '
! B, 310 "fc ,,51*0
D
ft'
' B a ^a * *^a i?
0.26 -
X D
+ <
3 0.5 -
S ^ "Jg
?|^o D * a
* 0.25 -
X X \ *** * "
o a$8> =h a a a
D a
X xxx X x "x-t,
0.4 -
^S^^^a^
+ + + +*
0.24 -
+ n
a TD
cPn* 1 D
+ + + + "*"+* +
x a
D ""b D 44.
+ +1|. + + + > +
0.23 -
x + x + o
a
0.3 -
rjDD + +
+ + + >+* + + * + t
x D
0.2 -
+
0.22 -
4-
14-i
7 0.9
HW
1.1 1
3 0.
> 0.82 -i
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
94 0.98 1 .02 1 .06 1.1 1.14 1.18 1 .22 1 .26
HW
34
1.35 -
workers
+ spinicola, northern popns.
X spinicola, southern popns.
D satanicus
a
D
35 a-
0.78 -
0.76 -
workers D
+ spinicola, northern popns. a D
X spinicola, southern popns.
D satanicus a D
1.3 -
a o
; o =^
0.74 -
o
1.25 -
+ x
0.72 -
x
x
+ D o
0.7 -
"xx + t
1.2 -
x XX
0.68 -
* \ a% o*
D D
5^
1.15 -
x* X x + *
0.66 -
x
xx +
0.64 -
x x x x x +
x # x + +
1.1 -
X + +
0.62 -
X +
X +
0.6 -
+ +
1.05 -
x
0.5B -
+
1 -
x
0.56 -
X X
95
*
0.54 -
0.52 -
+
O.S
4 0.98 1.02 1.06 1.1
1.14 1.18 1.22 1.26
O.S
4 0.98 1 .02 1 .06 1.1 1.14 1.18 1 .22 1 .26
HW
HW
36 5
workers
+ peperi
37
1.05 -
workers a D
-i- peperi n o
1.4 -
X nigrocinctus, particeps
D
X nigrocinctus, particeps a o aa
D others
i i * a a
1 -
D others ^ D^D D tf *
1.3 -
^^v-
0.95 -
B B ^gaB
1.2 -
B
"Jg." >s
b^So? D
0.9 -
*:*/ !^^ aaZ
0.85 -
i + ^fi
Wp tJ D
a
X * A HrJra
B^ D
'
v v -H-* BC Cf[ri
x x ** ag<*
=0
0.8 -
4 + D ggiP n n D
1 -
"****** B"
x4^ D "%
0.75 -
x *+j< + % ^
x x^f + ^"Q D a
^rv * u Q
0.7 -
|^ X cP D D
0.9 -
V* x ao
"*+
0.65 -
x X
0.8 -
0.6 -
Figs. 30-37. Scattergram plots of various metric measurements and indices in workers and queens of the
Pseudomyrmex ferrugineus group, "other species" refers to all others in the P. ferrugineus group.
128
JOURNAL OF HYMENOPTERA RESEARCH
42
44
O.BS -
workers
39 .
x *
workers
O.8 -
+ peperi
X nigrocinctus, particeps
a a
0.58 -
X x
4- peperi
X nigrocinctus, particeps
D others
O crf
0.56 -
jfffe x
D others
0.75 -
n_^*
."
0.54 -
* x x
0.7 -
Hi tf n V-8
0.52 -
** D
o
o SB,* o* #
0.5 -
x
D D Q,
0.65 -
+ + +
D nSr^Jb a aa a D D
to 0.48 -
TJ G
SO rfl
0.6 -
**>**
f*?
o a 3o cpogi
n uSb^ o
Q. 0.46 -
0.44 -
GO %OH a,
O B. D^ n 9-J ^ 9iP
0.55 -
0.5 -
fc<* x
&' :-?
ff BjB'tBBo
a Cf a
_OrP D
-* 1
a
0.42 -
0.4 -
0.38 -
+ + + .
+ +
* D aDBo na
.** D a a D
0.45 -
^t*
D
0.36 -
+ * +
B
x *x D on
0.34 -
+
t* DO
0.7 0.9
1.1 1.3 0.7
0.9 1.1 1
HW
HW
0.52 -
****** *
41 0.3
workers D
legend as in Fig. 39 a
0.5 -
* * ******
D
0.46 -
Rjo
0.48 -
**.r ******
a a
0.44 -
* * * e a"<&>
0.46 -
******
an 'Sa
0.42 -
" *' 8b "n^o^ *
0.44 -
** *
o a ^ fl D
0.4 -
*
*J oil? W '"t
a ff ft jp ?f] ^3 a a
0.38 -
+r*^
a %?PJ a D
0.42 -
0.4 -
X X G D rO
DLJ^ Gigjfjo
* 0.36 -
e*f
ego^ig^i 11 * D Q
X x D C
D ^ e T On
0.34 -
* * +
oj CD t>t 6nj" 1 ^
0.38 -
+
0.32 -
Q o D 3ti P
0.36 -
> X X x
G r3feOQ a D
0.3 -
*+ \ x
aVe
0.34 -
X x*x* X
*J G^ o D G
0.28 -
x^x^
aPo
Q D
0.32 -
QD t w 3 a B
0.26 -
^x
0.3 -
workers
legend as in Fig. 39
a
D
0.24 -
Xx G
X
0.7 0.9
1.1 1.3 o.7
0.9 1.1 1
HW
HW
0.5 -
0.49 -
workers
-I- particeps
D nigrocinctus
t
43
^~* 49 -
workers
+ particeps
n nigrocinctus
+
0.48 -
+
0.48 -
*
0.47 -
*
0.47 -
+
0.46 -
+
0.46 -
+
0.45 -
0.45 -
+
+ +
G D
jj
+ + D
0.44 -
0.44 -
G a D
* a a
0.43 -
+
* a
0.43 -
+ D D D
+ a a
0.42 -
a
03
0.42 -
o a a
D D
0.41 -
o D
0.41 -
a D D
0.4 -
0.4 -
D
D
iii
' ' '
HL
LHT
0.74 -
0.72 -
0.7 -
workers
+ veneficus
X mixtecus
a flavicornis
a
D
D aa
ao a
45 *-
0.45 -
0.44 -
0.43 -
workers
-f- veneficus
X mixtecus
n flavicornis
D
D
O.68 -
o a
0.42 -
D
n Q D
0.66 -
a a n
O D "- 1
0.41 -
D H D
0.64 -
D
0.4 -
D
0.62 -
X
D
0.39 -
0.6 -
cP
^ a o D
D.38 -
tt 0.37 -
X X
0.58 -
x *
x a
0.36 -
x X
0.56 -
0.35 -
x D
0.54 -
+ x
0.34 -
x x a
0.52 -
+ * + + X
0.33 -
D
0.5 -
f +
0.32 -
* ++ + +
0.48 -
*+ D
0.31 -
0.3 -
+
0.46 -
0.29 -
* +
a
0.44 -
0.42 -
+ X
0.28 -
n 97 -
x +
Figs. 38-45. Scattergram plots of various metric measurements and indices in workers of the Pseudomyrmex
ferrugineus group, "others" refers to all other species in the P. ferrugineus group.
VOLUME 2, NUMBER 1, 1993
46'
129
48
50
52
queens
+ veneflcus
D D
47 'Z\
queens D D
+ veneflcus o
0.95 -
X mixtecus * a jp D
O ferrugineus, flavicornis x x* x aoSjiBi
0.54 -
X mixtecus x x
rj ferrugineus, flavicornis x n D 'rf 1 D
0.9 -
A janzeni
X X OCD D D
0.52 -
4 nigrocinctus , particeps x o a
a a
0.5 -
& peperi D D a
0.85 -
**** a a a
0.48 -
* + D D _ a
+ * A *
DD 8
0.8 -
* * * A
J 0.46 -
* r+ * a ^o
* t **
0.44 -
* * + + D D
0.75 -
9 a
I ^* A A
0.7 -
+
0.42 -
:k* *
*
0.4 -
** ** *
0.65 -
** * *
0.38 -
* * :
0.6 -
55 -
*
0.36 -
n TA
* /
0.9 1.1
1.3 1.5 0.75 0.85 0.95 1.05 1.15
HL HW
. _ . ~
0.42 -
0.41 -
workers +
+ janzeni
D Mexican ferrugineus
4^,04-
1.02 -
queens
-h flavicornis D D *
D ferrugineus + +.
0.4 -
o
* a en
1 -
a o +
0.98 -
D 4-
0.39 -
D _
0.96 -
a a a D
0.38 -
+
D gl
0.94 -
a D o a
0.37 -
D
+ D
0.92 -
n 4-
0.36 -
* Q
D D
* 0.9-
a
0.35 -
+ +
a
0.88 -
n
D
J a
0.86 -
o
0.34 -
a
D
D g
0.84 -
a
0.33 -
A
*
0.82 -
0.32 -
O
0.8 -
A
0.31 -
0.3 -I
4-
0.78 -
n 7K
4 A*
A
0.92 0.94 0.96 0.98
1 1.02 1.04 1.06 1.08 1.1 1.12 1.14 0.96 1 1.04 1.08 1.12 1.16
HW HW
0.6 -
0.59 -
workers
-* flavicornis
P ferrugineus
D
Q
*
3 _L 0.53 -
0.52 -
+
0.58 -
4-
0.51 -
* * D
0.57 -
D *+ + *
0.5 -
* t * ,
O.56 -
? Q +
0.49 -
o a e
0.55 -
* i
3 On D * 4-+* +
0.48 -
a S D ** +
0.54 -
D
D D n *
0.53 -
a ao
B " * +
_l
B D B n n + * *
0.52 -
tb ^
W 0.46 -
i a cP D *
O.51 -
a o
D
0.45 -
DQC tD D a a
0.5 -
o o D Q
a
O.44 -
D u
0.49 -
1
a a o
0.43 -
D D P S o
8
0.48 -
a
0.42 -
O.47 -
0.41 -
workers D a
0.46 -
0.45 -
a
O
0.4 -
-t- flavicornis D a a
D ferrugineus
0.92 0.96 1
1 ' 1 1 1 1 1 1 1 1 w.j [ [ 1 1 1 1 1 1 1 1 1 1 p 1 1
1 .04 1 .08 1.12 1.16 1 .2 0.8 0.82 0.84 0.86 0.88 0.9 0.92 0.94
HW Cl
n R -^
0.82 -
queens
+ spinicola
53
workers
"x H- gracilis
0.8 -
0.78 -
0.76 -
D D a
X satanicus
D ferrugineus complex
A others
D
0.75 -
0.7 -
X nigropilosus
\ x x x x Q opaciceps
x x x x A simulans
x reconditus
a
0.65 -
* A
0.74 -
D n
If f x ^x x X
** A *
0.72 -
* A
DD n O X X
D a u + * x
5 ' 6 -
A * *
0.7 -
^4ft%
83 go w^ff + * +
+ + + *
A A A r
a cD ff^ -iP
0.55 -
+ + * +
0.68 -
A A f*
*
/> *\ **,**
0.66 -
**
*" * + 4-
0.5 -
0.64 -
D ^ * + .> + . * + *v* +
0.45 -
0.62 -
+ *
fi 1
0.6 -
A A
+ + 4.
O.4 -
a
Figs. 46-53. Scattergram plots of various metric measurements and indices in Pseudomyrmex workers and queens.
46-52, P. ferrugineus group; "others" refers to all other species in the P. ferrugineus group; "P. ferrugineus
complex" refers to a complex of five species: ferrugineus, flavicornis, janzeni, mixtecus and veneficus; 53, P.
gracilis group.
1 30 JOURNAL OF HYMENOPTERA RESEARCH
KEY TO PSEUDOMYRMEX SPECIES ASSOCIATED WITH SWOLLEN-THORN ACACIAS
(BASED ON WORKERS AND QUEENS)
The following key includes all species of Pseudomyrmex which have been found inhabiting swollen-
thorn acacias in Mexico, Central America, or Colombia. Pseudomyrmex ants can be distinguished from
others by their possession of a distinct postpetiole (i.e. "waist" consists of two nodes), well developed
sting, relatively large eyes (eye length more than one-third head length), and short antennal scapes (one
half head width or less). In the key below, species of Pseudomyrmex which are believed to be obligate
inhabitants of acacia are in bold print. These species are typically rather aggressive (but this is not true
of P. subtilissimus or P. nigropilosus), while the remaining facultative inhabitants are timid, generalist,
stem-nesting Pseudomyrmex which usually occupy swollen-thorn acacias only sporadically.
Couplets 11-19 cover the P. ferrugineus group, the principal group of obligate acacia-ants and the
focus of this study. Taxonomic comments on the other acac/a-inhabiting species are presented in a later
section of the paper (pp. 153- 162). Worker sizes exclude nanitic workers, i.e. the first-emerging
miniature workers associated with colony-founding queens.
1 . Standing pilosity very sparse on the head, including the gula (underside), and on the mesosoma; 1 ,0,
and 0-1 pairs of erect setae on the pronotum, mesonotum, and propodeum, respectively, of the
worker 2
Standing pilosity common to abundant on most parts of the body, including the gula and mesosoma;
worker usually with more than 10 standing hairs visible in outline on the mesosoma dorsum, not
arranged in isolated pairs 4
2. Very small, light brown species (worker and queen HW < 0.60), with elongate head (CI < 0.66) and
low, dorsally flattened petiole (PLI < 0.76) (Nicaragua, Costa Rica) subtilissimus (Emery)
Larger species (worker and queen HW > 0.70), with broader head (CI > 0.70) and higher petiole (PLI
> 0.80) (Figs. 1,2) 3
3. Smaller species (worker and queen HW < 1.00), with posterodorsally angulate petiole (Fig. 2)
(Mexico to Colombia) ita (Forel)
Larger species (worker and queen HW> 1.15), with posterodorsally rounded petiole (Fig. l)(Mexico
to Ecuador, Brazil) boopis (Roger)
4. Head with scattered, fine punctulae on a smooth, shiny background; punctulae on upper third of head
separated by several times their diameters or more 5
Head opaque to sublucid, more coarsely and densely punctulate, the punctulae subcontiguous on
most parts of the head 6
5. Larger species (HW> 1.20), with broad head (CI 1.12) and abundant long pilosity (Fig. 3) (Mexico
to Argentina, Brazil) kuenckeli (Emery)
Small species (HW < 0.72), with elongate head (CI 0.80) and shorter, sparser pilosity (Fig. 4)
(Mexico) hesperius, sp.nov.
6. Eyes relatively large and elongate (e.g. Fig. 5), eye length more than one-half head length (worker
and queen REL 0.52-0.65); pronotum laterally submarginate; outer surfaces of tibiae usually with
standing pilosity (may be very short); larger species, worker HW > 1.20; palp formula 6,4 7
Eyes smaller (Figs. 10-19), usually less than one-half head length (worker and queen REL 0.38-0.50);
pronotum laterally rounded; outer surfaces of tibiae without standing pilosity; medium-sized species,
worker HW < 1.28; palp formula 5,3or 4,3 (ferrugineus group) 11
7. Petiole long and slender, with a well developed anterior peduncle (worker and queen PLI 0.42-0.57)
VOLUME 2, NUMBER 1 , 1 993 1 31
(Figs. 5,6) 8
Petiole less elongate, with a short anterior peduncle (PLI > 0.59) (Figs. 7-9, 53) 9
8. Head densely punctulate-coriarious, presenting a matte appearance; head and mesosoma black, with
a contrastingly pale orange petiole, postpetiole, and gaster; petiole very slender, worker PLI 0.42-0.47
(Figs. 5, 53) (southern Mexico, Guatemala) opaciceps, sp. nov.
Head densely punctulate but retaining a subopaque to sublucid (not matte) appearance; color variable
but without the preceding pattern in Mexico or Guatemala; petiole usually less slender, worker PLI
0.46-0.57 (Figs. 6, 53) (throughout the Neotropics) gracilis (Fabricius)
9. Larger species (worker HW 1.47- 1.54, queen HW 1.66), with broad head (worker CI 1.00- 1.02, queen
CI 0.92) (Nicaragua) reconditus, sp. nov.
Smaller species (worker HW 1. 21-1.41, queenHW 1.15-1. 36); head more elongate (worker CI 0.84-
0.90, queen CI 0.77-0.80) 10
10. Standing pilosity short, pale and inconspicuous (Fig. 9); pronotum sharply margined laterally; petiole
longer, worker PLI 0.61-0.66, queen PLI 0.63-0.68; color black (Panama) simulans Kempf
Standing pilosity long and conspicuous, with long curved black setae arising from the propodeum and
petiole (Fig. 7); pronotum with blunter lateral margination; petiole short and high, worker PLI 0.69-
0.77, queen PLI 0.68-0.75; color variable, usually pale or bicolored (Mexico to Costa Rica)
nigropilosus (Emery)
1 1 . Median clypeal lobe of worker concave, with sharp lateral angles or teeth (Figs. 10, 1 1); legs long in
relation to body size (Figs. 30, 3 1 ); larger species (worker HW > 0.92, worker LHT > 0.88, queen HL
> 1.40, queen LHT > 1.05); frontal carinae closely contiguous, worker FCI2 0.24-0.42 (Fig. 32);
propodeum punctulate to coriarious-imbricate, posterolateral portions sublucid with little or no
overlying, coarse, rugulo-punctate sculpture 12
Median clypeal lobe of worker laterally rounded or subangulate (without sharp angles or teeth) (Figs.
12-19); legs shorter in relation to body size (Figs . 30, 3 1 ); size variable but if as large as the preceding
(worker HW > 0.92, etc.) then frontal carinae relatively well separated, worker FCI2 > 0.43 (Fig. 32),
and posterolateral portions of propodeum opaque to subopaque, overlain by coarse (although often
weak and ill-defined) rugulo-punctate sculpture 13
1 2. Larger species (worker HW > 1 .09, queen HW > 1 .20); head broader, its posterior margin straight and
rounding rather sharply into the sides (Figs. 10, 34); median clypeal lobe of worker longer and
narrower (Fig. 33); worker with a conspicuous, pit-like impression on midline of head, anterior to the
median ocellus; palp formula 4,3 (Panama) satanicus (Wheeler)
Smaller species (worker HW 0.94-1. 15, queenHW 0.94 - 1.14), with head a little less broad and its
posterior margin rounding more gently into the sides (Figs. 10, 34); median clypeal lobe of worker
notably shorter and broader (Fig. 33); worker usually lacking a pit-like impression on mid-line of
head; palp formula almost invariably 5,3, rarely 5p4,3 (Honduras to Colombia
spinicola (Emery)
13. Smaller species (worker HW 0.74-0.90, queen HW 0.76-0.85); head, propodeum, and petiole more
elongate, for a given head width (Figs. 36-38) 14
Larger species (worker HW 0. 85- 1 .2 1 , queen HW 0. 84- 1.19); head, propodeum, and petiole shorter,
for a given head width (Figs. 36-38) 16
14. Petiole and postpetiole very broad (worker PWI 0.63-0.75, worker PWI3 0.33-0.46, worker PPWI
1.41-1.83; queen PWI2 0.69-0.78) (Figs. 40, 41), the petiolar node with conspicuous posterolateral
angles, in dorsal view (Fig. 24); head very finely and densely punctulate-coriarious, presenting a
matte (opaque) appearance; palp formula 4,3 (Mexico to Nicaragua) peperi (Forel)
Petiole and postpetiole relatively narrow (worker PWI 0.49-0.61 , worker PWI3 0.50-0.61, worker
PPWI 1 .03- 1 .30; queen PWI2 0.57-0.63), the petiolar node without conspicuous posterolateral angles
1 32 JOURNAL OF HYMENOPTERA RESEARCH
(Figs. 22,23); head densely punctulate, sublucid to subopaque, but without a matte appearance; palp
formula 5,3 15
15. Workers and queens light orange-brown, with a fuscous patch on anterior third of abdominal tergite
IV (first gastric tergite); eyes relatively short (worker EL/LHT 0.56-0.61, queen REL2 0.58-0.66)
(Figs. 13, 42, 43); queen head less elongate (queen CI 0.67-0.72) (Guatemala to Costa Rica)
nigrocinctus (Emery)
Workers and queens entirely dark brown; eyes longer (worker EL/LHT 0.59-0.64, queen REL2 0.69-
0.70) (Figs. 14, 42, 43); queen head more elongate (CI 0.61, in the two known specimens) (Costa
Rica) particeps, sp. nov.
16. Small species (worker HW 0.85-0.95, queen HW 0.84-0.96) with head, gaster, and at least part of
mesosoma very dark brown to black; body pubescence dense, decumbent to suberect, and conspicu-
ous, especially on the petiolar node (Fig. 28); standing pilosity often (not always) sparse; head weakly
shining (western Mexico) veneficus (Wheeler)
Body pubescence dense but predominantly appressed, petiolar node without conspicuous suberect
pubescence; usually larger (worker HW 0.89-1.21, queen HW 0.96-1.19) with more conspicuous
standing pilosity; color and head sculpture variable 17
17. Head and gaster (typically also mesosoma) very dark brown to black; head densely punctulate and
opaque 18
Body lighter in color: light orange-brown to medium brown, rarely dark brown; head at least weakly
sublucid between ocelli and upper margin of the compound eye 19
18. Smaller species, worker HW 0.89-1.03, queen HW 0.96-1.01; petiole relatively longer and higher
(Figs. 44-47) (southern Mexico) mixtecus, sp. nov.
Larger species, worker HW 0.99-1.21, queen HW > 1.10; petiole relatively shorter and lower (Figs.
44-47) (Guatemala to Costa Rica) .flavicornis (F. Smith)
19. Head and mesosoma light orange-brown, the gaster similar or slightly darker; underside of head (gula)
with conspicuous suberect pubescence (Fig. 19); profile of worker mesosoma as in Fig. 29; smaller
species (worker HW 0.93-1.03, queen HW 0.96-1.00) with shorter, higher petiole (Figs. 46-49)
(western Mexico) .janzeni, sp. nov.
Gaster (and usually head) medium to dark brown, mesosoma variable; gular pubescence usually more
appressed and inconspicuous; in profile worker mesosoma usually with basal face rounding more
gradually into declivitous face (Fig. 27); size variable but larger on average (worker HW 0.92-
1 . 15,queen HW 0.92-1 . 12), with longer and lower petiole (Figs. 46-49) (eastern and southern Mexico
to Honduras) .ferrugineus (F. Smith)
KEY TO MALES OF THE OBLIGATE ACACIA-ANTS,
PSEUDOMYRMEX FERRUGINEUS GROUP
Although isolated acacia-ant males are unlikely to be encountered, the following key is offered as a
supplement for determination of species in the P. ferrugineus group. It can be used to confirm worker-
or queen-based identifications, but some couplets require examination of the male genitalia.
1 . Posterior margin of subgenital plate (sternite IX) with a shallow (less than semicircular) concavity
(Fig. 54); scape short, SI2 0.33-0.43, SL/HL 0.21 2
Posterior margin of subgenital plate (sternite IX) with a deep, semicircular concavity (Fig. 55); scape
longer, SI2 0.43-0.56, SL/HL 0.22 3
2. Paramere, in lateral view, with a slender finger-like mediodorsal lobe and angulate posteroventral
corner (Fig. 57) particeps
Paramere, in lateral view, with a stubbier mediodorsal lobe and more gently rounded posteroventral
VOLUME 2, NUMBER 1, 1993
133
corner (Fig. 56) nigrocinctus
3. Scape and compound eye longer, relative to HW (SI 0.29-0.35; REL2 0.56-0.62 (n=6)); head
narrower, CI 0.82-0.94, HW 0.81-0.95; lateral view of paramere as in Figs. 58a, 58b peperi
Scape and compound eye shorter (SI 0.22-0.30, REL2 0.49-0.58); head broader, CI 0.94 and/or HW
0.96; lateral view of paramere not as in Figs. 58a, 58b 4
4. Paramere, in lateral view, with posterodorsal corner well separated from mediodorsal lobe (Figs. 59-
60) 5
Paramere, in lateral view, with posterodorsal corner bent upward and enclosing a space between itself
and the mediodorsal lobe which is subequal to the area of the latter (Figs. 61-65) 6
5. Lateral view of paramere as in Figs. 59a and 59b: mediodorsal lobe relatively broad and partly
enclosing a space between itself and the posterodorsal corner; larger species, HW 1.06-1.09
(n=5) satanicus
Paramere typically as in Fig. 60a, with mediodorsal lobe more slender and more distant from
posterodorsal corner (Fig. 60b depicts a less typical male, from Colombia); smaller species, HW 0.92-
1.05 (n=12) spinicola
6. Mediodorsal lobe of paramere stout, directed more or less dorsally (Figs. 61, 62) 7
Mediodorsal lobe of paramere more slender and directed posterodorsally (Figs. 63-65) 8
7. Body pubescence dense and conspicuous, suberect on dorsum of head, propodeum and petiole;
smaller species, HW 0.79-0.88 (n=7) veneficus
Body pubescence less dense and less conspicuous, predominantly appressed or decumbent on the
propodeum and petiole; larger species, HW 0.88-0.97 (n=6) mixtecus
8. Smaller species, HW 0.93-0.96 (n=6) janzeni
Larger species, HW 0.99-1.19 (n=22) .ferrugineus andflavicornis
PSEUDOMYRMEX FERRUGINEUS GROUP
Introduction
Worker, diagnosis. Medium sized species (HW
0.74- 1 .26, HL 0.86- 1 .42); head varying from mod-
erately elongate to rather broad (CI 0.75-0.97), with
relatively short eyes (REL 0.39-0.50, REL2 0.45-
0.62) (Figs. 10-19). Masticatory margin of man-
dible with 6, rarely 7, teeth, MD8/MD9 0.70;
mesial tooth on basal margin notably closer to
apicobasal angle than to proximal tooth, MD4/
MD5 0.74. Palp formula 5,3, reduced to 4,3 in two
species. Anterior margin of median clypeal lobe
somewhat blunt-edged, in dorsal view convex,
straight or concave, laterally rounded or with sharp
angles. Frontal carinae separated by about basal
scape width in most species but more closely con-
tiguous in two (FCI 0.03-0. 10, FCI2 0.24-0.75, ASI
0.52-0.73), fusing anterolaterally with antennal
sclerites. Funicular segments II and III about as
broad as long (FLI 1 .46-2.45). Profemur slender (FI
0.35-0.41). Pronotum laterally rounded. Metanotal
groove well marked (MPI 0.04-0.09). Basal and
declivitous faces of propodeum moderately well
differentiated and subequal in length (PDI 0.94-
1.30), in profile the juncture between the two
subangulate or gently rounded (Figs. 20-29). Peti-
ole relatively long (PL/HL 0.44-0.63), always much
longer than high or wide (PLI 0.47-0.7 1 , PWI 0.46-
0.75), small anteroventral tooth present; in two
species anterior peduncle of petiole weakly differ-
entiated and posterolateral corners of petiolar node
not expanded (these are presumably the
plesiomorphic conditions in the group), in other
species petiole with distinct anterior peduncle and
with expanded, (sub)angulate posterolateral cor-
ners. Postpetiole broader than long (PPWI 1.03-
1.85), with small anteroventral tooth. Body sculp-
ture varying from densely punctulate or punctulate-
coriarious to coriarious-imbricate, the integument
sublucid to opaque; dorsum of head never with
extensive smooth, shiny interspaces (punctulae
usually separated by their diameters or less);
propodeum of some species overlain by a coarser
but weak rugulo-punctate sculpture. Standing pi-
losity common, present on the scapes, head, entire
mesosoma dorsum (10 or more standing hairs vis-
ible in profile), petiole, postpetiole and gaster,
134
JOURNAL OF HYMENOPTERA RESEARCH
54
57
58b
60b
61a
63b
62
1 mm
64b
Figs. 54-66. Pseudomyrmexferrugineus group, male terminalia. Figs. 54-55: sternite IX; Figs. 56-65 : left paramere,
lateral view, caudal end to right; Fig. 66: left paramere, mesial view. 54, P. particeps (Rincon, Costa Rica); 55, P.
mixtecus (near Tehuantepec, Mexico); 56, P. nigrocinctus (lOmi. NW Liberia, Costa Rica); 57, P. particeps
(Rincon, Costa Rica); 58, P. peperi (58a: 3km ENE Chiapa de Corzo, Mexico; 58b: Nueva Ocotepeque, Honduras);
59, P. satanicus (59a: 3mi. SW Gatun Dam, Panama; 59b: Marajal, Panama); 60, P. spinicola (60a: Madden Dam,
Panama; 60b: Aracataca, Colombia); 61, P. mixtecus(61&: 57. 8mi. S Chilpancingo, Mexico; 61b: near Tehuantepec,
Mexico); 62, P. veneficus (5km E Chamela, Mexico); 63, P.flavicornis (63a: Rio Oro, Costa Rica; 63b: 3.6mi. W
Choluteca, Honduras); 64, P. janzeni (64a: 60mi. SE Acaponeta, Mexico; 64b: 4mi. E San Bias, Mexico); 65, P.
ferrugineus (65a: Escuintla-Cd. Guatemala, Guatemala; 65b: 10.8mi S Pichucalco, Mexico); 66, P. ferrugineus
(10.8mi S Pichucalco, Mexico).
VOLUME 2, NUMBER 1, 1993
135
absent from the extensor faces of tibiae. Appressed
pubescence dense on most of body, including head
and abdominal tergite IV. Color varying from light
yellow- or orange-brown to black.
Queen diagnosis. Similar to worker except for
caste-specific differences. Larger in size (HW 0.76-
1.36, HL 1.05-1.81), head more elongate (CI 0.60-
0.80). Ocular indices differing slightly: REL 0.38-
0.48, REL2 0.51-0.70. Median clypeal lobe nar-
rower and more protruding, anterior margin convex
or straight, laterally rounded or subangulate. Peti-
ole and postpetiole generally more slender (PL/HL
0.57-0.72, PLI 0.43-0.63, PWI 0.47-0.67, PPWI
1.06-1.50). Forewing with 2 cubital cells.
Male, diagnosis. Head varying from longer
than broad to slightly broader than long (CI 0.82-
1.04 in a sample of 70 males belonging to all
species); compound eye large, prominent (REL2
0.49-0.62). Mandibles with 8+ teeth or denticles on
masticatory margin. Palp formula as in females,
but somewhat more variable (males with 5p4,3
commoner than in workers or queens). Surface of
median clypeal lobe convex, its anterior margin
subtriangular in shape (dorsal view) with sides
converging medially to a rounded point. Petiole
and postpetiole more slender than in workers (PLI
0.40-0.55, PWI 0.35-0.51) and simpler in shape.
Posterolateral corners of sternites IV- VIII not nota-
bly protruding ventrally. Subgenital plate (sternite
IX) with a conspicuous posteromedial concavity
(Figs. 54, 55). Posterior margin of pygidium (terg-
ite VIII) convex, directed posteroventrally.
Paramere with several characteristic features: a
finger-like, posterodorsally directed mediodorsal
lobe; angulate or expanded posterodorsal extrem-
ity; and mesial dorsoventral ridge which joins the
mediodorsal lobe posteriorly. Aedeagus with ex-
panded posterodorsal corner, a medial protrusion
on the posterior margin,numerous small teeth (15+)
on the posterior margin, and on the outer face a
raised ridge curving posterodorsally from a basal
origin.
Comments. Workers and queens of the P.
ferrugineus group can be distinguished from all
other Pseudomyrmex by their possession of the
following combination of traits: mandibles with 6-
7 teeth; palp formula 5,3 or 4,3; standing pilosity
common on mesosoma dorsum but absent from
external faces of tibiae; worker metanotal groove
conspicuously impressed; and head densely
punctulate, sublucid to opaque. The relatively
short eyes (worker REL 0.50, queen REL 0.48)
and slender petiole (worker PLI 0.71, queen PLI
0.63) are also characteristic. Among the eight
other major species groups of Pseudomyrmex
(diagnosed in Ward, 1 989) only the P. viduus and P.
oculatus groups have workers and queens approach-
ing these conditions. Those of the P. viduus group
have a shinier head, a shorter and more robust
petiole (worker PLI > 0.70, worker PWI > 0.70),
and standing pilosity on the tibiae (reduced in one
species), while workers and queens of the P. oculatus
group have a palp formula of 6,3 (reduced to 5,3
only in smallest species with worker and queen HW
< 0.67), tectiform and sharp-edged median clypeal
lobe with a broadly convex margin (dorsal view),
elongate eyes (worker REL 0.48-0.6 1 , worker REL2
0.62-0.86, queen REL 0.43-0.57, queen REL2 0.68-
0.89), and short petiole (worker PLI 0.67-1.06,
queen PLI 0.57-0.94). Among taxonomically iso-
lated species not belonging to one of the major
species groups, P.fervidus (F. Smith) bears perhaps
the closest phenetic resemblance to the P.
ferrugineus group, but its workers and queens can
be distinguished by their shinier and less densely
punctulate head, shorter petiole (worker PLI 0.71-
0.76, worker PL/HL 0.41-0.44 (n=9); queen PLI
0.65, queenPL/HL 0.49), and standing pilosity on
the outer faces of the tibiae. In addition the queens
of P. fervidus have a distinctive, pointed median
clypeal lobe not seen in P. ferrugineus group queens.
Males of the Pseudomyrmex ferrugineus group
can be characterized by their palp formula, medi-
ally subangulate clypeal lobe, emarginate subgenital
plate, configuration of the paramere, and shape of
the aedaegus. They are approached most closely in
this combination of traits by males of P. haytianus
(Forel) and two undescribed Central American
species (P. sp. PSW-02 and P. sp. PSW-54) al-
though, curiously, the workers and queens of those
species do not bear a close resemblance to those of
the P. ferrugineus group.
All species in the P. ferrugineus group are
obligate inhabitants of Central American swollen-
thorn acacias, a biological trait not characterizing
any other species group of Pseudomyrmex, al-
136
JOURNAL OF HYMENOPTERA RESEARCH
though a few species in the otherwise quite differ-
ent P. gracilis group and one species in the P.
subtilissimus group have independently developed
an obligate association with the acacias.
Distribution. Members of the P. ferrugineus
group are found from eastern (San Luis Potosi,
Tamaulipas) and western (Sinaloa) Mexico south
through Central America to northern Colombia
(Fig. 67). Although no single species spans the
entire range of the group, their collective distribu-
tion is virtually identical to that of the swollen-
thorn acacias (compare Fig. 67 with Janzen 1974:3).
Synonymic List of Species
P. ferrugineus (F. Smith 1877) Mexico to Hondu-
ras
= P.fulvescens (Emery 1890) (Ward 1989)
= P. canescens (Wasmann 1915) (Ward 1989)
= P. wasmanni (Wheeler 1921) (replacement
name for canescens)
= P. bequaerti (Wheeler 1942) (Ward 1989)
= P. saffordi (Wheeler 1942) (Ward 1989)
= P. vesanus (Wheeler 1942) (Ward 1989)
= P. bequaerti (Enzmann 1945) (Brown 1949)
= P. honduranus (Enzmann 1945) (Ward 1989)
P.flavicornis (F. Smith 1877) Guatemala to Costa
Rica
= P. belti (Emery 1890) (Ward 1989)
= P. obnubilus (Menozzi 1927a) (Ward 1989)
= P.fellosus (Wheeler 1942) (Ward 1989)
P. janzeni Ward, sp. nov. Mexico
P. mixtecus Ward, sp. nov. Mexico
P. nigrocinctus (Emery 1890) Guatemala to Costa
Rica
= P. alfari (Forel 1906) syn. nov.
= P. bicinctus (Santschi 1922) syn. nov.
= P. peltatus (Menozzi 1927) syn. nov.
P. particeps Ward, sp. nov. Costa Rica
P. peperi (Forel 1913) Mexico to Nicaragua
= P. convarians (Forel 1913) (Ward 1989)
= P. saffordi (Enzmann 1945) (Ward 1989)
P. spinicola (Emery 1890) Honduras to Colombia
= P. atrox (Forel 1912) syn. nov.
= P. gaigei (Forel 1914) syn. nov.
= P. infernalis (Wheeler 1942) syn. nov.
= P. scelerosus (Wheeler 1942) syn. nov.
= P. infernalis (Enzmann 1945) (Brown 1949)
= P. scelerosus (Enzmann 1945) (Brown 1949)
P. satanicus (Wheeler 1942) Panama
P. veneficus (Wheeler 1942) Mexico
= P. venificus (Enzmann 1945) (Brown 1949)
SPECIES ACCOUNTS
Pseudomyrmex ferrugineus (F. Smith 1877)
(Figs. 18,27,65,66,70)
Pseudomyrma ferrugineaF. Smith 1877:64. Lec-
totype worker, Mexico (BMNH) [Examined].
Pseudomyrma beltiracefulvescens Emery 1 890:64.
Lectotype worker, Guatemala (Beccari) (MCSN)
[Examined] [Synonymy by Ward 1989:437; see
also Janzen 1967b:391].
Pseudomyrma canescens Wasmann 1915:321.
Syntype workers, Tampico, Mexico (Brakhoven)
(MCSN, MCZC) [Examined] [Synonymy by
Ward 1989:437].
Pseudomyrma wasmanni Wheeler 1921:92. Re-
placement name, now unnecessary, for P.
canescens Wasmann 1915 (nee F. Smith 1877).
Pseudomyrma belti subsp. bequaerti Wheeler
1942:164. Lectotype worker, Puerto Castilla,
Honduras (J. Bequaert) (MCZC) [Examined]
[Synonymy by Ward 1989:437].
Pseudomyrma belti subsp. saffordi Wheeler
1942:162. Lectotype worker, Chicoasen,
Chiapas, Mexico (G. N. Collins) (MCZC) [Ex-
amined] [Synonymy by Ward 1989:437].
Pseudomyrma belti subsp. vesana Wheeler
1942:163. Holotype (unique syntype) worker,
Cordoba, Mexico (F. Knab) (MCZC) [Exam-
ined] [Synonymy by Ward 1989:437].
Pseudomyrma belti subsp. bequaerti Enzmann
1945:80. Syntype workers, Puerto Castilla,
Honduras (J. Bequaert) (MCZC) [Examined]
[Objective synonym of P. belti bequaerti
Wheeler; Brown 1949:42].
Pseudomyrma kuenckeli var. hondurana Enzmann
1945:87. Lectotype worker, Honduras (Bates)
(MCZC) [Examined] [Synonymy by Ward
1989:437].
Pseudomyrmex ferruginea [sic] (F. Smith); Janzen
1966:252.
Pseudomyrmex ferrugineus (F. Smith); Kempf
VOLUME 2, NUMBER 1, 1993
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JOURNAL OF HYMENOPTERA RESEARCH
1972:218.
Worker measurements (n = 69). HL 0.99- 1.33,
HW 0.92-1.15, MFC 0.054-0.108, CI 0.81-0.94,
REL 0.42-0.48, REL2 0.48-0.54, OOI 1.39-3.16,
VI 0.60-0.78, FCI 0.054-0.101, SI 0.41-0.46, SI2
0.79-0.91, NI 0.61-0.72, PLI 0.54-0.69, PWI 0.56-
0.73, PPWI 1.34-1.70.
Worker diagnosis. Medium-sized species (HW
> 0.91; LHT 0.75-1.06) with broad head (CI >
0.80); anterior margin of median clypeal lobe straight
or weakly concave, rounded laterally; palp formula
5,3; frontal carinae well separated (FCI > 0.05) and
median lobe of antennal sclerite not strongly ex-
posed (FCI2 0.45-0.69); mesosomal profile typi-
cally as in Fig. 27, with mesonotum notably in-
clined and with basal face of propodeum rounding
gradually into declivitous face, but deviations from
this pattern occur; petiole relatively short, high and
wide (see relevant metrics: PLI, PWI), with a dis-
tinct anterior peduncle (PWI3 0.36-0.50); postero-
lateral angles of petiole moderately developed but
not as pronounced as in P. peperi (compare Figs. 24
and 27) ; postpetiole broad. Head densely punctulate,
predominantly opaque or subopaque but at least
weakly shining on upper third of head between
ocelli and compound eye; mesosoma punctulate to
punctulate-coriarious, subopaque to sublucid; pos-
terior portions of propodeum opaque to subopaque
and usually overlain by larger but weak, irregular
punctures or rugulae. Petiole, postpetiole and gaster
with fine piligerous punctures, sublucid. Standing
pilosity common; pubescence dense but fine and
appressed on most surfaces. Color variable, from
light reddish- or yellowish-brown to very dark
brown, gaster (and usually head) somewhat darker
than the mesosoma; mandibles, scapes, fronto-
clypeal complex, and apices of legs usually lighter.
Comments. Workers and queens of P.
ferrugineus can be recognized by features of head
morphology (laterally rounded median clypeal lobe,
well separated frontal carinae and correspondingly
limited exposure of the median lobes of the anten-
nal sclerites, and moderately broad worker head;
see Fig. 1 8), head sculpture (densely punctulate and
(sub)opaque, but weakly shining on upper third of
head between the ocelli and compound eye), and
coloration (variably brown, not black or orange-
brown). This species is most likely to be confused
with the allopatric P. janzeni and the partly sympa-
tric P.flavicornis. See under those species for more
specific discussion.
Distribution and biology. P. ferrugineus is
distributed from eastern and southern Mexico to El
Salvador and Honduras (Fig. 70). It is a common
species and colonies have been recorded from all
swollen-thorn acacia species growing within its
range, i.e. Acacia chiapensis, A. collinsii, A. cookii,
A. cornigera, A. gentlei, A. globulifera, A. hindsii,
A. janzenii, A. mayana and A. sphaerocephala. P.
ferrugineus is usually monogynous (Janzen 1967b,
1973) but a few alcohol nest series from Guate-
mala, belonging to apparently mature colonies (as
judged by the presence of alates), contained more
than one dealate queen. Janzen (1966, 1967b)
conducted a massive experimental study of the
interaction between P. ferrugineus and Acacia
cornigera in Mexico, and the results of these ex-
periments, together with copious additional obser-
vations by Janzen, showed conclusively that the
ants protect the acacia from herbivores and compet-
ing plants (especially vines). P. ferrugineus was
also the subject of a study on kinship and nestmate
recognition among workers (Mintzer 1982; Mintzer
et al. 1985) which demonstrated a worker-based
and probably inherited component to colony odor.
Statements about the biology of "P. ferruginea"
from regions south of El Salvador and Honduras
(e.g. Janzen 1983) refer to a different species, P.
spinicola.
Material examined (AMNH, BMNH, CASC,
CHAH, CISC, CUIC, INHS, LACM, MCSN,
MCZC, MHNG, MNHN, MZSP, NHMV, PSWC,
SEMC, UCDC, USNM, WPMC).
BEUZEBelize: 2.2mi W Belize, rd.to Chetumal
(D.HJanzen); 3.8mi NW Belize, rd.to Chetumal
(D.H.Janzen); 4.9mi SW Belize, rd.to Cayo
(D.HJanzen); Belize (Baker; c.u.); Manatee [River]
(J.D.Johnson; c.u.); nr. Belize (N.L.H.Krauss);
Cayo: 36.1mi SW Belize (D.H.Janzen); 36.1mi
[S]W Belize (U.Kansas Mex.Exped.); El Cayo
[=San Ignacio] (N.L.H.Krauss); Pine Mtn. Ridge,
Mecal R., 415m (G.D.Alpert); San Ignacio
(S .E.Schoenig) ; Corozal: 1 3 .5mi S Sta.Elena (Lou-
isville) (D.H.Janzen); 15mi S Sta.Elena (Louis-
ville) (D.H.Janzen); Orange Walk: 5mi SE Orange
VOLUME 2, NUMBER 1, 1993
139
Walk, rd.to Belize (D.H.Janzen); Toledo: Punta
Gorda (H.Broomfield).
EL SALVADOR Chalatenango: 4.7mi NW La
Palma, 880m (D.H.Janzen); 5.5mi SE La Palma,
11 30m (D.H.Janzen).
GUATEMALA A Ita Verapaz'. San Joaquin, nr.
San Cristobal Verapaz, 1080m (D.H.Janzen); Trece
Aguas (Schwarz & Barber); Chimaltenango:
Yepocapa (H.T.Dalmat); Coatepeque: 2mi W
Coatepeque (D.H.Janzen); ElProgreso: 4.9mi SW
Sanarate, 780m (D.H.Jan/en); Escuintla: 1.7mi S
Escuintla, 370m [on CA-2] (D.H.Janzen); 12.6mi
NE Escuintla, rd. to Cd. Guatemala, 1120m
(D.H.Janzen); 15km E Escuintla [on CA-9]
(D.H.Janzen); 3mi N Escuintla [on CA-9]
(D.H.Janzen); 3mi S Escuintla [on CA-9]
(D.H.Janzen); 43km S Cd. Guatemala [=15km E
Escuintla] (D.H.Janzen); 6.8mi S Escuintla, 280m
[on CA-2] (D.H.Janzen); 8.3mi N Escuintla [on
CA-9] (D.H.Janzen); 9. 2mi N Escuintla, 900m [on
CA-9] (D.H.Janzen); Escuintla (W.M.Wheeler);
Pantaleon (Champion); Guatemala: 16.2mi NE
Cd.Guatemala (D.H.Janzen); 19kmS Cd.Guatemala
[on CA-9] (D.H.Janzen); 20mi SE Cd.Guatemala,
1060m [on CA-1] (D.H.Janzen); 6.2mi NE
Cd.Guatemala, 700m (D.H.Janzen); 7.9mi S Cd.
Guatemala, 1360m [on CA-9] (D.H.Janzen); 8. Imi
NE Cd. Guatemala, 850m (D.H.Janzen); Cd. Gua-
temala (Champion); Cd. Guatemala, 980m
(D.H.Janzen); Escuintla-Cd.Guatemala [=19km S
Cd. Guatemala] (D.H.Janzen); Huehuetenango:
12.4mi SE Mex. border at Cd. Cuauhtemoc
(D.H.Janzen); 12.5mi SE Mex.border at Cd.
Cuauhtemoc (D.H.Janzen); 37.6mi NW
Huehuetenango, 900m (D.H.Janzen); 7. Imi SE
Mex.border at Cd. Cuauhtemoc (D.H.Janzen); 9.3mi
SE Mex.border at Cd. Cuauhtemoc (D.H.Janzen);
Izabal: l.lmi NE Quirigua, 120m (D.H.Janzen);
2. Imi SW Morales, 50m (D.H.Janzen); Lago Izabal,
1km NE El Estor [= 1.5km NE El Estor]
(D.H.Janzen); Los Amates (Kellerman);
Murciellago (D.H.Janzen); Quirigua
(W.M.Wheeler); Jutiapa: 6.7mi N San Cristobal,
280m (D.H.Janzen); 6.9mi N San Cristobal, 290m
(D.H.Janzen); 9miSW Jutiapa, 950m (D.H.Janzen);
Peten: 70km NW Tikal (W.R.Tschinkel); Tikal
(T.H.Hubbell; N.L.H.Krauss; W.R.Tschinkel);
Quezaltenango: 7.2mi NE San Felipe, on
Retalhuleu-QuezaltenangoRd. (D.H.Janzen); 7.5mi
NE San Felipe, on Retalhuleu-Quezaltenango Rd.
(D.H.Janzen); Retalhuleu: 1.3mi E Champerico
(D.H.Janzen); 2mi NE Champerico (D.H.Janzen);
5mi W Retalhuleu (D.H.Janzen); 5mi W Retalhuleu,
Hwy. CA-2, at Rio Nil (D.H.Janzen); Champerico
(Baker; F.Knab); Puenta Samala, 3.8mi NE San
Felipe (D.H.Janzen); Retalhuleu (Stoll); SantaRosa:
25mi SE Escuintla, 200m [on CA-2] (D.H.Janzen);
Solola: "Pacific slope", 3000ft. (c.u.);
Suchitepequez: Patulul (W.M.Wheeler); Zacapa:
lOmi SW El Lobo, 170m [on CA-9] [=9.2mi NE
Piedras de Afilar] (D.H.Janzen); 2.6mi SW El
Lobo, 100m [on CA-9] [=16.6mi NE Piedras de
Afilar] (D.H.Janzen); 8. Imi SWLos Amates, 160m
[on CA-9] [=8.0mi NE El Lobo] (D.H.Janzen);
8.2mi NE Piedras de Afilar, 160m [on CA-9]
[=12.2mi NE Rio Hondo] (D.H.Janzen);
dept. unknown: "Guatemala" (Beccari); Concepcion,
1400ft. (C.N.Ainslie); Mimosa, "Cocepcion"
[Concepcion] (C.N.Ainslie).
HONDURAS Atldntida: Tela (quarantine New
Orleans, U.S.A.) (T.J.Baker); Colon: Puerto Castilla
(J.Bequaert); Comayagua: "Comayaena" (S.
Passoa); 1 1.7miS San Antonio, 830m (D.H.Janzen);
1 5.7mi N Siguatepeque, 530m (D.H.Janzen); Minas
de Oro (J.B.Edwards); Copdn: 10.4mi S Sta. Rosa
de Copan, 980m (D.H.Janzen); 1 1.9mi S Sta. Rosa
de Copan, 1130m (D.H.Janzen); 17.3mi N Sta.
Rosa de Copan, 780m (D.H.Janzen); Cortes: 24.6mi
SW San Pedro Sula, 240m (D.H.Janzen); 6.8mi S
San Pedro Sula, 480m [=20.9mi SW Quimistan]
(D.H.Janzen); San Pedro Sula (S.C.Bruner;
W.M.Mann); Ocotepeque: 4.4mi E [Nueva]
Ocotepeque, 13 10m (D.H.Janzen); Santa Barbara:
7.3mi E Quimistan (D.H.Janzen); 13.7mi SW
Quimistan, 320m (D.H.Janzen); Yoro: Coyoles, W
of Olanchito (Echternacht); dept.unknown: "Hon-
duras" (Bates).
MEXICO Camp.: 0. Imi S Tenabo (D.H.Janzen);
O.Smi E Campeche (D.H.Janzen); 10.6mi E
Campeche (D.H.Janzen) ; 20mi E Campeche,
Hwy. 1 80 (D.H.Janzen); 29mi E & 12mi S Campeche
(Ruinas Edzna)(D.H.Janzen); 48mi NE Puerto Real
(Isla Aguada), Hwy. 180 (D.H.Janzen); Ruinas
Edzna (U.Kansas Mex.Exped.); Chis.: 10 mi NE
[NW?] Tapachula [on Hwy. 200?] (D.H.Janzen);
140
JOURNAL OF HYMENOPTERA RESEARCH
10.8mi S Pichucalco (D.H.Janzen); llkm SE
Pichucalco, 400m (P.S.Ward); 11 mi E Arriaga
(D.H.Janzen); 1km WSW Palenque, 80m
(P.S.Ward); 26km E Cintalpa (W.MacKay); 2mi S
Pichucalco (D.H.Janzen); 32mi W [San] Cristobal
de las Casas, Hwy.190 (D.H.Janzen); 3km ENE
Chiapa de Corzo, 500m (P.S.Ward); 3mi N Soyalo
[on Hwy.195] (D.H.Janzen); 4mi NW Ocosingo
(R.C.Bechtel & E.I.Schlinger; R.F.Smith); 4mi S
Simojovel(R.C.Bechtel & E.I.Schlinger;
E.I.Schlinger); 56.9mi NE [NW?] Tapachula [on
Hwy.200?] (D.H.Janzen); 5mi SE Tapilula [on
Hwy.195] (D.H.Janzen); 6.9mi N Tapilula
(D.H.Janzen); 7mi SW Teapa [on Hwy.195]
(D.H.Janzen); 8.5mi S La Trinitaria, 1160m
(U.Kansas Mex.Exped.); 8.5mi S La Trinitaria,
Hwy.190 (D.H.Janzen); 8mi W Las Cruces,
Hwy.190, 660m (D.H.Janzen); 96km S Tuxtla
Gutierrez, 732m (D.E. & J.A.Breedlove);
Acapetahua Las Bugamvillas (F.Diaz); Arriaga
(D.H.Janzen); Cd. Cuauhtemoc (D.H.Janzen);
Chicoasen (G.N.Collins); El Real (Goodnight &
Stannard); Ixtacomitan (R.Andrews); Llano Grande
(G.N.Collins); Palenque (c.u.); Pichucalco
(G.N.Collins); Rio Huixtla, Huixtla (J.G.Pereira);
Ruinas Palenque (E.M.Fisher); San Sebastian [near
Tuxtla Gutierrez; see Safford 1922:393]
(G.N.Collins); Santo Domingo, 15mi SE [SW?]
Simojovel (R.F.Smith); Tapilula (D.H.Janzen);
Tonala, 40m (D.H.Janzen); Tonola [prob.=Tonala]
(A.Petrunkewitch); Tuxtla Gutierrez
(N.L.H.Krauss; W.P.Stoutamize); Yaxoquintela
(J.E.Rawlins); Yerba Santa (G.N.Collins);
Gro.:10mi NE Acapulco (D.H.Janzen); 15.8mi S
Chilpancingo (D.H.Janzen); 18mi S Chilpancingo
(F.D.Parker;F.D.Parker & L.A.Stange); 25.4mi S
Chilpancingo (D.H.Janzen); 55mi N Acapulco,
Hwy.95 (Cornell Univ.Mex.Field Party; c.u.);
57.8mi S Chilpancingo (D.H.Janzen); 59.9mi N
Acapulco (D.H.Janzen); 62.4mi N Acapulco
(D.H.Janzen); 74km N Acapulco (W.MacKay);
Acapulco (L.J.Lipovsky); Revolcadero
(N.L.H.Krauss); San Geronimo de Juarez (W.von
Hagen); Hgo.: 2km W Orizatlan, 245m
(W.MacKay); Mor.:15miSCuernavaca (E.S.Ross;
W.S.Ross); Cuernavaca (W.M.Wheeler); Oax.:
1 1.4-17.0mi W Tehuantepec (D.H.Janzen); Imi W
Temascal (D.H.Janzen); 22.2mi N Puerto
Escondido, 700m (D.H.Janzen); 25mi W
Tehuantepec (D.H.Janzen); 3.2miNE Tehuantepec
(D.H.Janzen); 42km N San Pedro Pochutla, 850m
(W.MacKay); 44mi W Tehuantepec (E.E.Gilbert
& C.D.MacNeil); 5mi E Temascal (D.H.Janzen);
9.6km E Santiago Astata, 1 Om (W.MacKay); Bahias
de Huatulco (W.MacKay); Pinotepa Nacional
(S.W.T.Batra); Salina Cruz (D.H.Janzen);
Tehuantepec (F.Knab; W.P.Stoutamize); Temascal
(H.V.Daly; D.H.Janzen); Temascal, 25m
(D.H.Janzen);Tuxtepec(J.CamelaG.; W.M.Mann);
Valle Nacional (G.V.Halffter); Q.Roo: 12.2mi S
Peto, Q.Roo- Yucatan border (D.H.Janzen); 16.9mi
W Cd. Chetumal, rd. to Peto (D.H.Janzen); 22.5mi
S Felipe Carillo Puerto (D.H.Janzen); 6.4mi E
Polyuc (D.H.Janzen); 7mi W Felipe Carillo Puerto
(D.H.Janzen); 8. Imi S Felipe Carillo Puerto
(D.H.Janzen); 8mi S Felipe Carillo Puerto
(D.H.Janzen); Sian Ka'an (A.Dejean); Sian Ka'an
Reserve, nr. Felipe Carillo Puerto (A.Dejean);
Vallarta (A.Dejean); S.L.P. : 27mi N Tamazunchale
(D.H.Janzen); 40-50mi NW Cd. del Maiz
(W.S.Ross); 4miN Valles, 300ft. (W.S.Creighton);
Cd. Valles (D.H.Janzen); El Bonito, 7mi S Cd.
Valles, 300ft. (P.H. & M.Arnaud); El Salto
(A.Mintzer; c.u.); Huichihuayan (L.J.Lipovsky);
Rio Amahac, Tamazunchale, 300ft. (W. S.
Creighton); Tamazunchale (D. H. Janzen; W. S.
Ross); locality not specified, prob. Tanquian [see
Safford 1923:390] (Safford); Tab. : 0.6mi S Paraiso
onrd. to Cardenas (D.H.Janzen); 0.9mi S Chontalpa
(D.H.Janzen); 12.8mi S Chontalpa (D.H.Janzen);
2. Imi E Frontera (D.H.Janzen); 3 mi W Cardenas
(D.H.Janzen); 30.2mi W Cd. El Carmen
(D.H.Janzen); 37.8mi E Coatzacoalcos, Hwy.180
(D.H.Janzen); 6.6mi S Chontalpa (D.H.Janzen);
Chontalpa, 26mi S Cardenas (D.H.Janzen);
Cardenas (D.H.Janzen); Teapa (J.C. & D.Pallister;
H.H.Smith; W.P.Stoutamize); Tamps.: 22.7mi S
Cd. Victoria (D.H.Janzen); 41mi S Cd. Victoria
(C.W.Obrien); 50mi N Valles (G.E.Bohart); 5mi N
Cd. Mante (A.Mintzer); 7km WSW El Encino,
140m (P.S.Ward); Antiguo Morelos (c.u.); Cd.
Madero (F.Infante M.); Ciudad Mante (N.E. &
M.A.Evans; N.L.H.Krauss); El Limon (H.E.Evans);
Forlon (L.J.Lipovsky); Gonzales (c.u.); Llera
(W.E.LaBerge); Mesa de Llera (A.Mintzer); N of
Antiguo Morelos (A.Mintzer); Rio Guayalejo at
VOLUME 2, NUMBER 1 , 1993
141
Hwy.85 (A.S.Menke&L.A.Stange); S of Cd. Mante
(A.Mintzer); Tampico (Brakhoven; D.L.Crawford;
H.Jourdan; N.L.H.Krauss; Locke; E. Palmer;
E.A.Schwarz; W.P.Stephen; c.u.); Tampico, dunes
at Cd. Madero (D.H.Janzen); Xicotencatl
(H.C.Millender); Ver.: "N.M.,Vera Cruz"
(Townsend); "Vera Cruz" (G.Seurat; H.H.Smith);
lOmi W Veracruz (G.E.Bohart); 14km ENE La
Tinaja, 50m (P.S.Ward); 15mi W Veracruz
(U.Kansas Mex.Exped.); 16km E Cuilahuac
[=Cuitlahuac] (W.MacKay); 24.9miNW Acayucan
(D.H.Janzen); 28km N Cardel, Morro de la Mancha
(V.Rico-Gray); 30mi S Acayucan (F.D.Parker);
3mi N Sayula (R.C.Bechtel; R.C.Bechtel &
E.I.Schlinger); 4mi NE Minatitlan (R.C.Bechtel &
E.I.Schlinger);4miNWRinconada Antigua, 1350ft.
(U.KansasMex.Exped.); 4mi W Puente Nacional,
900ft. (U.Kansas Mex.Exped.); 6.5km N Tierra
Blanca, 50m (W.MacKay); 7mi S Cardel, 600ft.
(c.u.); 9km NNW Sontecomapan, 20m (P.S.Ward);
Boca del Rio (U.Kansas Mex.Exped.); Buen Pais
(R.C.Bechtel & E.I.Schlinger); Camaron
(E.Skwarra); Cordoba (F.Knab; R.R.Snelling; c.u.);
Cotaxtla Exp. Sta., Cotaxtla (D.H.Janzen); Est.
Biol. Los Tuxtlas (H.A.Hespenheide); Est. Biol.
"Los Tuxtlas", nr. San Andres Tuxtla (G.Ibarra
M.); Fortin (c.u.); Jalapa (Rangel; W.M.Wheeler;
c.u.); Jalapilla, mun. Jilotepec (G.Aleman); Los
Cocos (A.Petrunkewitch); Los Tuxtlas, 10km NNW
Sontecomapan, 200m (P.S.Ward); Mirador
(E.Skwarra); Mocambo (D.H.Janzen); Orizaba
(c.u.); Palma Sola (Halffter & Reyes); Panuco
(F.Parker & D.Miller); Playa Azul, Catemaco
(W.P.Stoutamize); Pueblo Nuevo, nr. Tezonapa
(Cornell Univ. Mex. Field Party); Remutadero
(E.Skwarra); Santa Lucrecia [=Jesus Carranza]
(F.Knab; P.Knab); Tamarindo (E.Skwarra); Tamos
(F.C.Bishop); Tinajas [presumably La Tinaja, on
Hwy.150] (F.D.Parker & L.A.Stange); Tlacocintla
(E.Skwarra); Veracruz (G.E.Bohart; N.L.H.Krauss;
E.Skwarra; L.A.Stange); Yuc.: 14.8mi S Ticul,
"Hwy.180" [prob.Hwy.261] (D.H.Janzen); 8mi E
Merida (rd. to Pto. Juarez) (D.H.Janzen); Merida
(D.H.Janzen; N.L.H.Krauss); Merida (S margin of
town) (D.H.Janzen); Tekax, 33mi W Peto
(D.H.Janzen); Temax (Gaumer); state unknown:
"Mex"("Norton").
Pseudomyrmex flavicornis (F. Smith 1877)
(Figs. 16, 25, 63, 69)
Pseudomyrma flavicornis F. Smith 1877:67. Lec-
totype worker,Nicaragua (BMNH) [Examined].
Pseudomyrma belli Emery 1890:63. Syntype work-
ers, Alajuela, Costa Rica (BMNH, MCSN) [Ex-
amined] [Synonymy by Ward 1989:438].
Pseudomyrma belli var. obnubila Menozzi
1927a:273. Syntype worker, San Jose, Costa
Rica (H. Schmidt) (NHMB) [Examined] [Syn-
onymy by Ward 1989:438].
Pseudomyrma belli subsp. fellosa Wheeler
1942:160. Syntype workers, Nicaragua (W.
Fluck); Granada, Nicaragua (C. F. Baker)
(AMNH, LACM, MCZC) [Examined] [Syn-
onymy by Ward 1989:439].
Pseudomyrmex flavicornis (F. Smith); Kempf
1972:218.
Worker measurements (n = 29). HL 1 .06- 1 .42,
HW 0.99-1.21, MFC 0.075-0.114, CI 0.83-0.94,
REL 0.39-0.45, REL2 0.45-0.51, OOI 1.28-2.71,
VI 0.59-0.73, FCI 0.068-0.098, SI 0.40-0.46, SI2
0.82-0.97, NI 0.61-0.68, PLI 0.57-0.67, PWI 0.60-
0.72, PPWI 1.36-1.80.
Worker diagnosis. Similar to P. ferrugineus
(q.v.) except as follows. Larger, with shorter eyes,
on average (Figs. 16,50). Head densely punctulate,
opaque; overlying rugulo-punctate sculpture on
propodeum tending to be better developed than in
P. ferrugineus. Pilosity and pubescence denser on
average. Head black, gaster and postpetiole dark
brown to black, mesosoma and petiole varying
from black to a contrasting lighter brown or red-
dish-brown; mandibles, scapes, fronto-clypeal com-
plex, and apices of legs brown.
Comments. Key traits of this species are the
laterally rounded median clypeal lobe, large size
(worker HW > 0.98; queen HW 1.12-1.19, n=13),
broad opaque head (worker CI > 0.82; queen CI
0.73-0.76) and dark color. P. flavicornis is one of
three species in the P. ferrugineus group whose
workers and queens have a black or very dark
brown body (mesosoma sometimes contrastingly
lighter). The other two, P. mixtecusandP. veneficus,
are allopatric to P. flavicornis and smaller in size;
142
JOURNAL OF HYMENOPTERA RESEARCH
other distinguishing features are mentioned in the
key and discussed under those species. A tendency
towards lighter coloration of the mesosoma in north-
ern populations ofP.flavicornis sometimes makes
it difficult to distinguish this species from sympa-
tric dark-colored P. ferrugineus. Even the darkest
workers and queens of the latter species are, how-
ever, smaller (an average difference in workers,
almost absolute in P. ferrugineus queens which
have HW 0.96- 1 . 1 2 (n = 37)) with longer eyes (Fig.
50) and shorter scapes for a given relative head
breadth (Fig. 51); and they show some reflectance
of light on the upper third of the head between the
ocelli and compound eye in contrast to the more or
less opaque-headed P. flavicornis. In addition, P.
ferrugineus queens have more elongate heads (CI
0.68-0.73) than those of P. flavicornis.
Distribution and biology. This is a monogy-
nous species ranging from Guatemala to Costa Rica
(Fig. 69), which inhabits Acacia collinsii and, less
frequently, A. cornigera and A. hindsii. It was one
of the first acacia-ants to be brought to the attention
of naturalists, thanks to an early account of its
biology by Thomas Belt (1874) (under the name
Pseudomyrma bicolor). In the more recent litera-
ture P. flavicornis has usually been referred to as
"P. belli", but note that there is not a perfect
correspondence in name usage (Table 1).
Material examined (AMNH, ANSP, BMNH,
CASC, CUIC, INBC, LACM, MCSN, MCZC,
MZSP, NHBM, NHMV, PSWC, SEMC, UCDC,
USNM).
COSTA RICA Alajuela: Alajuela (A.Alfaro);
Atenas (A.Alfaro); Ojo de Agua (A.Alfaro); Tacares
(A.Alfaro); Turrucares (A.Alfaro); Guanacaste:
1.4mi N La Cruz, 200m (D.HJanzen); 10.7mi NW
Liberia (D.HJanzen); 1km S Canas (D.HJanzen);
2mi E Playa Coco (D.HJanzen); 2mi SE Canas
[=2mi S Canas] (D.HJanzen); 4km S
Canas(D.HJanzen); 5km S Liberia (D.HJanzen);
6mi E, 6mi S Canas (D.HJanzen); 6mi W Liberia
(D.HJanzen); 7km N Canas (D.HJanzen); Bahia
del Coco (A.Alfaro); Ballena, Rio Tempisque
(A.Alfaro); El Coco (R J.Hampton); FincaTaboga,
6mi S, 6mi W Canas (D.HJanzen); Hda. LaPacifica,
5km NW Canas (E.R.Heithaus); Hda. La Pacifica,
nr. Canas, 50m (P.S.Ward); La Cueva, 12km N
Liberia (D.HJanzen); Liberia (A.Alfaro;
M.G.Naumann); Palo Verde (D.E.Gill;
H.A.Hespenheide; D.HJanzen; D.Whitacre); Palo
Verde, 50m (D.M.Olson); Palo Verde, <100m
(J.Longino); Rio Corobici, nr.Canas (R.M.Bohart);
Santa Cruz (P.P.Calvert); Santa Rosa Natl. Pk.
(F Joyce); Santa Rosa Natl. Pk., 300m (J.Longino;
P.S.Ward); Santa Rosa Natl. Pk., 5m (P.S.Ward);
Santa Rosa Natl. Pk., <5m (P.S.Ward); Tempisque
(A.Alfaro); Heredia: Lagunilla (C.H.Ballow);
Puntarenas: 1km NE Tarcoles, 20m (P.S.Ward);
4km E Tivives, 5m (L.S.Farley); Barranca,near
Puntarenas (A.Alfaro); San Jose: Bebedero
(A.Alfaro); Rio Oro (D.HJanzen); San Jose
(Nauck;H.Schmidt); Villa Colon (A.Alfaro); Villa
Colon, 600-700m (J.Longino); prov. unknown:
"Costa Rica"(c.u.); Ciruela(J.F.Tristan).
EL SALVADOR Ahuachapan: 7.8mi S
Hachadura, 50m (D.HJanzen); Chalatenango:
5 .4mi N La Palma, 850m (D .H Janzen) ; La Libertad:
2.6miS Santa Tecla,1010m[=11.8miNLaLibertad]
(D.HJanzen); 2mi E La Libertad (D.HJanzen); La
Libertad (E.S.Ross); Quezaltepeque (D.Cavagnaro
& M.E.Irwin); La Union: 7. Imi W Amatillo, 190m
(D.HJanzen); Lapaz: 11.6mi W Zacatecoluca, Om
(D.HJanzen); San Miguel: 0.4mi W San Miguel
(D.H Janzen); betw. La Union & San Miguel, 1 10m
(D.HJanzen); San Salvador: San Salvador
(O.L.Cartwright; N.L.H.Krauss); Sonsonate:
34.4mi W La Libertad (D.HJanzen); 6.6mi S
Sonsonate [=43. 6mi W La Libertad] (D.HJanzen);
Usulutan: E slope Cerro Verde, 3800ft.
(D.Q.Cavagnaro & M.E.Irwin); dept. unknown: Los
Chorros (D.Q.Cavagnaro & M.E.Irwin); Los
Chorros Natl. Pk. (M.E.Irwin).
GUATEMALA Escuintla: 12.6miNEEscuintla,
rd. to Cd. Guatemala, 1120m (D.HJanzen); 15km
E Escuintla [on CA-9] (D.HJanzen); 43km S Cd.
Guatemala [=15km E Escuintla] (D.HJanzen);
Guatemala: 19km S Cd. Guatemala [on CA-9]
(D.HJanzen); 7.9mi S Cd. Guatemala [on CA-9]
(D.HJanzen); Amatitlan (Bates); Escuintla-
Cd. Guatemala [=19km S Cd. Guatemala]
(D.HJanzen); Lake Amatitlan (c.u.);Jutiapa:47mi
S Escuintla, 250m [=47mi SE Escuintla]
(D.HJanzen); 7.7mi E Jutiapa, Hwy.l, 900m
(D.HJanzen); 9.7mi E Jutiapa, 750m (hwy.to San
Cristobal) [=9.3miNE Jutiapa] (D.HJanzen); Santa
Rosa: 12.2mi W Taxisco (D.HJanzen); 3.8mi S
VOLUME 2, NUMBER 1, 1993
143
Guazacapan (D.H.Janzen); Guazacapan
(R.H.Painter); Zacapa: lOmi SW El Lobo, 170m
[on CA-9] [=9.2mi NE Piedras de Afilar]
(D.H.Janzen); 2.6rai SW Rio Hondo, 200m [on
CA-9] (D.H.Janzen); 22.3mi SW Quirigua [on CA-
9] (D.H.Janzen); 22.3mi SW Quirigua [on CA-9]
(D.H.Janzen); 8.2mi NE Piedras de Afilar, 160m
[on CA-9] [=12.2miNE Rio Hondo] (D.H.Janzen);
km 142 on Guatemala-Pto. Barrios Rd. nr. Los
Amates (D.H.Janzen).
HONDURAS Choluteca: 19mi NE Choluteca
(D.H.Janzen); 3.6mi W Choluteca, 200m
(D.H.Janzen); 4.5mi W Choluteca (D.H.Janzen);
Colon: Puerto Castilla (J.Bequaert); Valle: 4.6mi E
Jicaro Galan, 1 90m (D .H. Janzen) ; La Union, 28 .4mi
E El Amatillo (frontera) (D.H.Janzen).
NICARAGUA Chontales: no specific locality
(T.Beit); Esteli: 2mi N Condega, 500m
(D.H.Janzen); Granada: 2.2mi W Nandaime
(D.H.Janzen); 2mi N Nandaime, 160m
(D.H.Janzen); Granada (C.F.Baker); Leon: 28.1mi
SE Leon (D.H.Janzen); Managua: S.lmi E San
Benito (D.H.Janzen); 8.8mi N Tipitapa
(D.H.Janzen); 9.9miNEMasachapa,Hwy.8, 180m
(D.H.Janzen); 9mi N Tipitapa, 50m (D.H.Janzen);
Matagalpa: 15.8mi NW Sebaco [=15.8mi W
Sebaco] (D.H.Janzen); 2.6miNDario (D.H.Janzen);
4.1mi S Matagalpa, 650m (D.H.Janzen); 4.5mi SE
Dario (D.H.Janzen); Rivas: Imi N San Juan del Sur
(D.H.Janzen); Imi NW Penas Blancas [=lmi N
Penas Blancas] (D.H.Janzen); 20.5mi NW Penas
Blancas (D.H.Janzen); 4.4miSELa Virgen [=4.4mi
S La Virgen] (D.H.Janzen); Isla Ometepe (F.Joyce);
La Virgen [on Hwy.l] (D.H.Janzen); San Juan del
Sur, 10m (D.H.Janzen); Zelaya: Wounta Hanlover
(Fluck); dept.unknown: "Nicaragua" (W.Fluck;
c.u.).
Pseudomyrmex janzeni Ward, sp.
(Figs. 19, 29, 64, 70)
nov.
Holotype worker. MEXICO, Nayarit: 60 mi.
SE Acaponeta, Hwy. 15, 15.ix.1963, D. H. Janzen
(LACM). HW 1 .00, HL 1 .08, EL 0.5 1 , PL 0.55, PH
0.36.
Paratypes. Same data as holotype: series of
166 workers, 62 queens and 45 males (AMNH,
BMNH, CASC, EBCC, GBFM, INBC, LACM,
MCZC, MZSP, PSWC, UCDC, USNM). Addi-
tional non-type material is listed below.
Worker measurements (n = 12). HL 1 .00- 1.18,
HW 0.93-1.03, MFC 0.063-0.096, CI 0.88-0.94,
REL 0.45-0.47, REL2 0.49-0.52, OOI 1.45-2.29,
VI 0.58-0.68, FCI 0.068-0.098, SI 0.42-0.45, SI2
0.84-0.91, NI 0.62-0.69, PLI 0.59-0.71, PWI 0.63-
0.73, PPWI 1.37-1.73.
Worker diagnosis. Very similar to P.
ferrugineus (q.v.) except as follows. Size smaller,
on average. In lateral view mesonotum less steeply
inclined; basal and declivitous faces of propodeum
forming a less obtuse angle (compare Figs. 27 and
29). Petiole shorter and higher, on average (Fig.
48). Weak rugulo-punctate sculpture on propodeum
even less evident than in P. ferrugineus. Pubes-
cence denser, becoming decumbent to suberect on
parts of body, most notably the gula (Fig. 19). Head
and mesosoma rather light orange-brown, gaster
the same or a slightly darker brown.
Comments. Within the P. ferrugineus group
P. janzeni can be characterized by its relatively
small size (worker and queen HW < 1.04), broad
head (worker CI > 0.86), laterally rounded median
clypeal lobe, and uniform orange-brown color. P.
janzeni is evidently closely related to P. ferrugineus
(as surmised by Janzen 1973); all of the metric
measurements and indices of these two species
overlap, although there is a tendency for P. janzeni
workers to have shorter, higher petioles (Fig. 48).
Workers and queens of P. janzeni are perhaps best
distinguished from those of P. ferrugineus by the
combination of lighter orange-brown color, suberect
gular pubescence (best seen in a backlit lateral view
of the head), and the flatter profile of the worker
mesosoma (see description above and Fig. 29).
While some individuals of the highly variable P.
ferrugineus approach these conditions there is no
indication of a convergence towards this morphol-
ogy in western Mexico (Guerrero) where popula-
tions of P. ferrugineus come closest to those of P.
janzeni.
Distribution and biology. First recognized by
Janzen (1967a, 1969, 1973) as a distinct but
undescribed species, P. janzeni is confined to a
limited area in western Mexico (Fig. 70) where it is
sympatric with the much darker colored and com-
144
JOURNAL OF HYMENOPTERA RESEARCH
moner P. veneficus. Colonies occupy Acacia hindsii
and are polygynous; additional details of the life
history can be found in Janzen's (1973) paper on
polygynous acacia-ants.
Material examined. Type material listed above,
plus the following (LACM, MCZC, PSWC, UCRC,
USNM).
MEXICO Jal. : Puerto Vallarta (J. A.Comstock) ;
Nay.: 14.5mi E San Bias (D.HJanzen); 2mi E San
Bias (R.van den Bosch); 31mi N Tepic
(D.HJanzen); 36mi N Tepic (D.HJanzen); 4mi E
San Bias (M.Irwin; M.Irwin & E.I.Schlinger;
EJ.Schlinger); 5mi E San Bias (F.Parker &
D.Miller); Compostela (c.u.); Rio Palillo, 14mi E
San Bias (D.HJanzen); Tepic (H.A.Scullen); Sin.:
20mi E Villa Union (E.I.Schlinger).
Pseudomyrmex mixtecus Ward, sp. nov.
(Figs. 15, 26, 55, 61, 69)
Holotype worker. MEXICO, Guerrero: 25.4
mi. S. Chilpancingo, 10.viii.1966, D. H. Janzen
#M0088 10966 (LACM). HW 0.97, HL 1.07, EL
0.48, PL 0.55, PH 0.35.
Paratypes. Same data as holotype, and three
other accession numbers (M0078 10966,
M0098 10966, MO 108 10966) with same locality,
date, and collector: series of 43 workers, 34 queens
and 17 males (AMNH, BMNH, CASC, EBCC,
GBFM, INBC, LACM, MCZC, MZSP, PSWC,
UCDC, USNM). Additional non-type material is
listed below.
Worker measurements (n= 13). HLO.94-1.19,
HW 0.89-1.03, MFC 0.054-0.073, CI 0.86-0.95,
REL 0.42-0.47, REL2 0.46-0.52 OOI 1 .22-2.28, VI
0.61-0.73,FCI0.056-0.073,SI0.43-0.45,SI20.86-
0.97, NI 0.60-0.65, PLI 0.60-0.68, PWI 0.60-0.68,
PPWI 1.40-1.73.
Worker diagnosis. Similar to P. ferrugineus
(q.v.) except as follows. Size smaller (HW < 1.04,
LHT < 0.90), head broad (CI > 0.85); frontal
carinae separated by about basal scape width or less
(FCI2 0.45-0.54). Basal and declivitous faces of
propodeum forming a less obtuse angle in profile
than typical for P. ferrugineus (compare Figs. 26
and 27). Head densely punctulate, opaque. Stand-
ing pilosity rather common, usually some setae
exceeding 0.12 mm and 0.20 mm in length on
mesosoma dorsum and petiole, respectively. Pu-
bescence dense but appressed. Very dark brown to
black, appendages lighter.
Comments. P. mixtecus is distinguished from
all other species, except P. veneficus and P.
flavicornis, by its laterally rounded median clypeal
lobe, broad head, and black (or very dark brown)
body. It differs from P. veneficus by the fully
opaque head, absence of conspicuous suberect pu-
bescence on the petiole, and larger size. P. mixtecus
is evidently closely related to P. flavicornis but
averages smaller in size (compare worker HW and
LHT values), a difference which is absolute in
queens (queen HW 0.96- 1.01 (n=8), whereas queen
HW > 1 . 1 1 in P. flavicornis). In addition the petiole
is relatively longer and higher, for a given head
width, in both workers and queens of P. mixtecus
(Figs. 44-47).
Distribution and biology. P. mixtecus is known
only from the Mexican states of Guerrero and
Oaxaca (Fig. 69). Colonies have been collected
from Acacia hindsii and A. collinsii, but little more
has been recorded about their biology. Janzen's
field notes indicate that this species is monogynous.
Material examined. Type material listed above,
plus the following (CUIC, LACM, MCZC, MZSP,
PSWC, SEMC, USNM, WPMC).
MEXICO Gro.: lOmi NE Acapulco
(D.HJanzen); 29.6mi N Acapulco, 1400ft.
(D.HJanzen); 30mi N Acapulco, Hwy.95 (Cornell
Univ. Mex. Field Party); 57.8mi S Chilpancingo,
Hwy.95 (D.HJanzen); 74km N Acapulco
(W.MacKay); Acapulco (Baker; F.Knab;
N.L.H.Krauss; LJ.Lipovsky); Puerto Marques
(N.L.H.Krauss); San Geronimo de Juarez (W.von
Hagen); Oax.:l 1.4-17.0mi W Tehuantepec
(D.HJanzen); 13.8mi W Tehuantepec, 1500ft.
(D.HJanzen); 19km N San Pedro Pochutla, 200m
(W.MacKay); 6.0mi E Niltepec, Hwy.190, 100m
(D.HJanzen).
Pseudomyrmex nigrocinctus (Emery 1 890)
(Figs. 13, 22, 56, 72)
Pseudomyrmanigrocincta Emery 1890:64. Syntype
workers, queens, males, Alajuela, Costa Rica
(A. Alfaro) (BMNH, MCSN, MCZC, MHNG)
[Examined]. One syntype worker from MCSN
VOLUME 2, NUMBER 1, 1993
145
here designated LECTOTYPE.
Pseudomyrma alfariForel 1906:228. Twosyntype
workers, Tivives, embouchure de Jesus-Maria,
Costa Rica (A. Alfaro) (MHNG) [Examined].
One syntype here designated LECTOTYPE.
Syn. nov.
Pseudomyrma nigrocinta var. bicincta Santschi
1922:347. Syntype workers, Costa Rica
(MHNG, NHMB) [Examined]. One syntype
from NHMB here designated LECTOTYPE.
Syn. nov.
Pseudomyrma peltataMenozzi 1927a:273. Three
syntype workers, SanJose, Costa Rica (H.
Schmidt) (NHMB) [Examined]. Syn. nov.
Pseudomyrmex nigrocincta [sic] (Emery); Janzen
1966:252.
Pseudomyrmex nigrocinctus (Emery); Kempf,
1972:221.
Worker measurements (n = 21). HL 0.89- 1.08,
HW 0.74-0.85, MFC 0.035-0.051, CI 0.75-0.84,
REL 0.40-0.45, REL2 0.51-0.56, OOI 1.39-2.76,
VI 0.62-0.78, FCI 0.044-0.065, SI 0.44-0.48, SI2
0.81-0.89, NI 0.58-0.64, PLI 0.59-0.68, PWI 0.49-
0.61, PPWI 1.10- 1.30.
Worker diagnosis. Small species with elon-
gate head and short eyes (REL 0.45, REL2 0.56,
EL/LHT 0.61). Palp formula 5,3. Median clypeal
lobe rather narrow, its surface and anterior margin
convex. Frontal carinae separated by about basal
scape width (FCI 0.055). Metanotal groove well
marked; basal and declivitous faces of propodeum
subequal (Fig. 22). Petiole short (PLI > 0.57), its
anterior peduncle broad in dorsal view (PWI3 0.50-
0.61) and not well differentiated from the node
(Fig. 22). Petiole lacking expanded posterolateral
corners. Postpetiole less broad than in most other
species in the P. ferrugineus group (see PPWI
values). Head densely punctulate and subopaque,
becoming sublucid posteriorly where the punctulae
are separated by shiny interspaces. Mesosoma
punctulate to (laterally) coriarious-imbricate,
sublucid, becoming subopaque on the propodeum.
Standing pilosity moderately common (as in Fig.
22); pubescence dense and closely appressed. Or-
ange-brown, often with anterolateral fuscous patches
on abdominal tergite IV (these form a distinct
transverse black band in queens).
Comments. Workers and queens of P.
nigrocinctus are easily distinguished from all other
acacia ants, except P. particeps (see below), by
their small size (HW < 0.86 in both castes), elongate
head in the worker (worker CI < 0.85), and narrow
petiole andpostpetiole (worker PWI3 0.50, worker
PPWI 1 .30, queen PWI2 0.57-0.63). The orange
color and short eyes are also characteristic.
Distribution and biology. P. nigrocinctus is
found from Guatemala to Costa Rica, with most
records coming from the southern end of its range
(Fig. 72). Colonies are monogynous, and have
been collected from Acacia collinsii, A. cornigera
and A. hindsii. Records from Acacia gentlei and A.
globulifera (Beulig & Janzen 1969:59) need to be
confirmed because of possible confusion with P.
peperi. Janzen' s (1967b) observations on "P.
nigrocincta" in Mexico refer to P. peperi. On the
other hand descriptions of the biology and behavior
of P. nigrocinctus in Costa Rica (Janzen 1973,
1974, 1975, 1983; Beulig & Janzen 1969) are
reliably attributed to P. nigrocinctus.
Material examined (AMNH, ANSP, INBC,
LACM, MCSN, MCZC, MHNG, MZSP, NHMB,
PSWC, USNM, WPMC).
COSTA RICA Alajuela: Alajuela (A.Alfaro);
Atenas (A.Alfaro); Cascajal (A.Alfaro); Escobal
(A.Alfaro); Ojo de Agua (A.Alfaro); Turrucares
(P.P.Calvert); Guanacaste: 1.4mi N La Cruz
(D.HJanzen); 10.7mi NW Liberia (D.HJanzen);
lOmi NW Liberia, 70m (D.HJanzen); lOmi NW
Liberia, 70m [=10.7mi NW Liberia] (D.HJanzen);
2mi S Canas (D.HJanzen); 4km N Canas
(D.HJanzen); 5km S Liberia (D.HJanzen); 7km N
Canas (D.HJanzen); El Coco (R.J.Hampton); Finca
Taboga, 6mi S, 6mi W Canas (D.HJanzen); Garita
(A.Alfaro); Hda. La Pacifica, nr. Canas, 50m
(P. S. Ward); La Cueva, 12km N Liberia
(D.HJanzen); Palo Verde (D.E.Gill; D.HJanzen);
Palo Verde, 50m (D.M.Olson); Santa Cruz
(P.P.Calvert); Santa Rosa Natl. Pk., 290m
(P.S.Ward);SantaRosaNatl.Pk.,300m(J.Longino;
P.S.Ward); Santa Rosa Natl. Pk., 5m (P.S.Ward);
Santa Rosa Natl. Pk., <5m (P.S.Ward); Tempisque
(A.Alfaro); Puntarenas: 2km E Tivives, <5m
(L.S.Farley); Tivives (A.Alfaro); San Jose: 3.5km
NE Santiago de Pur (D.HJanzen); San Jose
146
JOURNAL OF HYMENOPTERA RESEARCH
(H.Schmidt; c.u.); prov. unknown: "Costa Rica"
(c.u.).
GUATEMALA Zacapa: 2.0mi NE Rio Hondo,
190m [on CA-9] (D.HJanzen); 22.3mi SW Quirigua
[on CA-9] (D.HJanzen).
HONDURAS Choluteca: 7.4miNECholuteca,
150m (D.HJanzen).
NICARAGUA Boaco: 11.7mi E San Benito
(D.HJanzen); Esteli: 13.1mi N San Isidro
(D.HJanzen); 2.5mi N Condega, 620m
(D.HJanzen); 6.8mi N San Isidro, 780m
(D.HJanzen); 7.5mi NW San Isidro, 550m
(D.HJanzen); Leon: Izapa (J.M.Maes); Madriz:
3mi W Somoto, 650m (D.HJanzen); Matagalpa:
15.8mi NW Sebaco (D.HJanzen); 2.6mi N Dario
(D.HJanzen); 4.5mi SE Dario (D.HJanzen); 4mi S
Dario, 350m (D.HJanzen); Rivas: 1km W Penas
Blancas (D.HJanzen); C.R. border, Imi N Penas
Blancas, <5m [=lmi NW Penas Blancas]
(D.HJanzen); Isla Ometepe (F Joyce).
Pseudomyrmex particeps Ward, sp. nov.
(Figs. 14, 23, 54, 57, 72)
Holotype worker. COSTA RICA, Puntarenas:
Rincon, Peninsula Osa, 3.iii.l965, D.H. Janzen#III
(LACM). HW 0.83, HL 1.10, EL 0.50, PL 0.50, PH
0.31.
Paratypes. Same data as holotype: series of 82
workers, 14 males, one queen (AMNH, BMNH,
CASC, GBFM, INBC, JTLC, LACM, MCZC,
MZSP, PS WC, UCDC, USNM). Additional non-
type material listed below.
Worker measurements (n = 12). HL 0.93- 1.10,
HW 0.77-0.83, MFC 0.037-0.050, CI 0.75-0.84,
REL 0.44-0.48, REL2 0.55-0.60, OOI 1.47-1.96,
VI 0.65-0.75, FCI 0.048-0.062, SI 0.45-0.49, SI2
0.78-0.83, NI 0.53-0.62, PLI 0.58-0.66, PWI 0.55-
0.60, PPWI 1.03- 1.26.
Worker diagnosis. Very similar to P.
nigrocinctus (q.v.) except as follows. Eyes longer
(REL2 0.55-0.60, EL/LHT 0.59-0.64) (Figs. 14,
42, 43). Front of head more strongly shining.
Medium to dark brown; gaster uniformly dark
brown or black; mandibles, fronto-clypeal com-
plex, and appendages lighter brown.
Comments. P. particeps is obviously a very
close relative of the allopatric P. nigrocinctus, but
there are consistent differences between the two in
eye size and color which exceed the limits of
variation seen throughout the much wider range of
P. nigrocinctus. Workers in the type series of P.
particeps also have more elongate heads than those
of P. nigrocinctus but this distinction is not seen in
other samples. Differences between queens of the
two species are more striking with the two known
queens of P. particeps having more elongate heads
(CI 0.61, compared with 0.67-0.72 in a sample of
1 3 P. nigrocinctus queens) and longer metatibiae
relative to head width (LHT/HW 1.12 versus
0.97-1.07 in P. nigrocinctus). Additional alates of
P. particeps are needed to confirm these differ-
ences and the apparent distinctions in male genita-
lia (see male key).
Distribution and biology. P. particeps is a rare
species known only from the Osa Peninsula and one
adjacent locality, in Costa Rica (Fig. 72). It appears
to be associated exclusively with Acacia allenii, a
forest species (see Janzen, 1974 for more informa-
tion aboutthehostplant). In contrast, P. nigrocinctus
is found farther north in more open habitats where
it typically inhabits Acacia collinsii. The differ-
ences in worker morphology between P. particeps
and P. nigrocinctus (darker color and more elon-
gate head and/or eyes in the former) parallel those
observed between populations of P. spinicola from
the same areas (see below under P. spinicola),
suggesting similar selection pressures associated
with more forested habitats and partial (P. spinicola)
or exclusive (P. particeps) occupancy of a different
Acacia species.
Material examined. Type material listed above,
plus the following (JTLC, LACM, PSWC).
COSTA RICA Puntarenas: 4mi S Rincon
(D.HJanzen); Bahia Drake, Osa Penin. (F.Joyce);
Corcovado Natl. Pk., Sirena, 50m (J.T.Longino);
Rincon (A.R.Moldenke); San Jose: 16.7mi SW San
Isidro on Hwy.22, 160m (D.HJanzen).
Pseudomyrmex peperi (Forel 1913)
(Figs. 12,24,58,71)
Pseudomyrma peperi Forel 1913:213. Syntype
workers, Patulul, Guatemala (Peper) (MHNG)
[Examined]. One syntype here designated
LECOTYPE.
VOLUME 2, NUMBER 1, 1993
147
Pseudomyrma spinicola race convarians Forel
1913:214. Syntype worker, Patulul, Guatemala
(Peper) (MHNG) [Examined] [Synonymy by
Ward 1989:452].
Pseudomyrma sabanica [sic] var. saffordiEnzmann
1945:89. Syntype workers, Yerba Santa,
Chiapas, Mexico (G. N. Collins) (MCZC) [Ex-
amined] One syntype here designated LECTO-
TYPE. [Synonymy by Ward 1989:452].
Pseudomyrmex peperi (Forel); Kempf 1972:222.
Worker measurements (n = 53). HL 0.86- 1.13,
HW 0.76-0.90, MFC 0.034-0.064, CI 0.76-0.89,
REL 0.45-0.50, REL2 0.54-0.62, OOI 1.15-2.06,
VI 0.59-0.79, FCI 0.042-0.071, SI 0.44-0.49, SI2
0.76-0.88, NI 0.62-0.71, PLI 0.54-0.65, PWI 0.63-
0.75, PPWI 1.41-1.83.
Worker diagnosis. Small species (HW < 0.92)
with moderately elongate head (Fig. 12); anterior
margin of median clypeal lobe straight or slightly
produced medially, laterally rounded or subangulate
(never sharply angulate as in P. spinicola and P.
satanicus). Palp formula 4,3, rarely 5p4,3. Frontal
carinae separated by about basal scape width.
Mesosomal and petiolar profile typically as in Fig.
24, but in some workers basal and declivitous faces
of propodeum less well differentiated and/or
anteroventral tooth of petiole more prominent.
Petiole and postpetiole broad, the former
subtriangular in dorsal view with well developed
posterolateral angles (Fig. 24). Dorsum of head
obscurely punctulate-coriarious, matte. Remainder
of body with finely punctulate to punctulate-
coriarious sculpture, opaque to sublucid; propodeum
lacking overlying rugulo-punctate sculpture seen
in P. ferrugineus. Standing pilosity not especially
abundant, sometimes lacking (worn?) on
mesonotum. Appressed pubescence abundant but
very fine. Light to medium brown, rarely dark
brown, the gaster sometimes darker than the rest of
body; appendages lighter.
Comments. P. peperi is recognized by the fea-
tures mentioned above and in the key. The combi-
nation of small elongate head, broad posterolaterally
angulate petiole, and matte head surface is found in
no other acacia ant workers or queens.
Distribution and biology. This species has a
rather wide distribution, from eastern Mexico to
Nicaragua (Fig. 71). It has been collected from
Acacia chiapensis, A. collinsii, A. cornigera, A.
gentlei, A. globulifera and A. hindsii. P. peperi is
apparently polygynous over much of its range, and
often occurs sympatrically with the commoner P.
ferrugineus. Some aspects of its biology in Mexico
are discussed by Janzen ( 1 967b) under the name "P.
nigrocincta" .
Material examined (AMNH, BMNH, CASC,
INHS, LACM, MCZC, MNHG, MZSP, NHMV,
PSWC, SEMC, UCDC, USNM).
BELIZE Belize: 16mi SW Belize, rd. to Cayo
(D.HJanzen); 5.5mi NW Belize, rd. to Chetumal
(D.H.Janzen); Cayo: 20km S Augustine, 300m
(G.D.Alpert); Sanlgnacio (S.E.Schoenig); Corozal:
15mi S Sta.Elena (Louisville) (D.H.Janzen).
EL SALVADOR Ahuachapan: 7.8mi S
Hachadura (D.HJanzen); Chalatenango: 2.5mi N
Tejutla, rd. to LaPalma, 580m (D.H.Janzen); 4.7mi
NW La Palma, 880m (D.H.Janzen); 5.5mi SE La
Palma, 1130m (D.H.Janzen); 7.5mi SE Tejutla,
320m (D.H.Janzen); La Libertad: 2-4km S
Quezaltepeque (W.L. Brown); 2mi E La Libertad
(D.H.Janzen); 5mi N Quezaltepeque (M.E.Irwin);
7.4miNLa Libertad (D.H.Janzen); Hda. Capolinas,
5kmNW Quezaltepeque, 450m (M.E.Irwin);
Quezaltepeque (M.E.Irwin); Santa Tecla [=Nueva
San Salvador] (P.Berry); La Union: 1 Arm W
Amatillo, 190m (D.H.Janzen); between La Union
& San Miguel, 100m [=22.3mi S Sirama]
(D.H.Janzen); between La Union & Usulatan, 1 50m
[=2.6mi S Sirama] (D.H. Janzen); Lapaz: 1 1.6mi W
Zacatecoluca, Om (D.H.Janzen); San Miguel: be-
tween La Union & San Miguel, 1 10m [=22.3mi E
Usulutan] (D.H.Janzen); Santa Ana: 5.3mi NW
Santa Ana, 660m (on Hwy.l) (D.H.Janzen);
Sonsonate: 24.2mi SE Hachadura (D.H.Janzen);
4.5mi S Sonsonate (D.H.Janzen); 41.4mi NW La
Libertad, 10m (D.H.Janzen).
GUATEMALA A/to Verapaz: San Joaquin, nr.
San Cristobal Verapaz, 1080m (D.H.Janzen); El
Progreso: 24.5mi NE Cd. Guatemala [on CA-9]
(D.H.Janzen); Escuintla: 1.7mi S Escuintla, 370m
[on CA-2] (D.H.Janzen); 43km S Cd. Guatemala
[=15km E Escuintla] (D.H.Janzen); Escuintla
(W.M.Wheeler); San Jose (E.S.Ross; E.I.Schlinger
& E.S.Ross); Guatemala: 19km S Cd. Guatemala
148
JOURNAL OF HYMENOPTERA RESEARCH
[on CA-9] (D.HJanzen); 20mi SE Cd. Guatemala,
1060m [on CA-1] (D.HJanzen); 7.9mi S Cd. Gua-
temala, 1360m [onCA-9] (D.HJanzen) ;Escuintla-
Cd. Guatemala [=19km S Cd. Guatemala]
(D.HJanzen); Izabal: 9.9mi SW Quirigua
(D.HJanzen); Lago Izabal, 1.5km NE El Estor
(D.HJanzen); Quirigua (D.HJanzen;
W.M.Wheeler); nr. Mariscos (D.HJanzen); Jutiapa:
11.5ml W Jutiapa, 900m (D.HJanzen); 12.3mi E
Guazacapan (D.HJanzen); 2.3mi NW Pijiji [=Pijije]
(D.HJanzen); 23mi E Taxisco (G.F. & S.Hevel);
3.4mi N San Cristobal, rd. to Jutiapa, 400m
(D.HJanzen); 47mi SE Escuintla, 250m [=47mi S
Escuintla] (D.HJanzen); 6.9mi N San Cristobal,
290m (D.HJanzen); 8.4mi N San Cristobal, 280m
(D.HJanzen); 9.7mi E Jutiapa, 750m (hwy.to San
Cristobal) [=9.3miNE Jutiapa] (D.HJanzen); Peten:
70km NW Tikal (W.R.Tschinkel); Tikal
(D.HJanzen; W.R.Tschinkel);fleta//zw/<?:2miNE
Champerico (D.HJanzen); 5mi W Retalhuleu
(D.HJanzen); 5mi W Retalhuleu, Hwy.CA-2, at
Rio Nil (D.HJanzen); Santa Rosa: 6mi S
Guazacapan (D.HJanzen); Suchitepequez: Patulul
(Peper); Zacapa: lOmi SW El Lobo, 170m [on CA-
9] [=9.2mi NE Piedras de Afilar] (D.HJanzen);
2.0mi NE Rio Hondo, 190m [on CA-9]
(D.HJanzen); 2.6mi SW El Lobo, 100m [on CA-9]
[= 1 6.6mi NE Piedras de Afilar] (D.HJanzen) ; 5 .6mi
NE Rio Hondo, 250m [on CA-9] (D.HJanzen);
8.1ml SW Los Amates, 160m [on CA-9] [=8.0mi
NE El Lobo] (D.HJanzen); 9.7mi NE Piedras de
Afilar, 150m [on CA-9] [=9.5mi SW El Lobo]
(D.HJanzen); Zacapa (W.M.Wheeler); km!42 on
Guatemala-Pto. Barrios Rd. nr. Los Amates
(D.HJanzen).
HONDURAS Choluteca: 19.3mi SW San
Marcos de Colon, on Hwy.l (D.HJanzen); 19mi
NE Choluteca (D.HJanzen); 20.4mi SW San
Marcos de Colon, 490m (D.HJanzen); 3.6mi W
Choluteca, 200m (D.HJanzen); 7.4mi NE
Choluteca, 150m (D.HJanzen); Colon: Trujillo,
80m (Echternacht); Comayagua: 11.7mi S San
Antonio, 830m (D.HJanzen); 4mi N Comayagua,
500m (D.HJanzen); Cortes: 24.6mi SW San Pedro
Sula, 240m (D.HJanzen); Francisco Morazdn:
24.3mi S Camayagiiela (Tegucigalpa), 1000m
(D.HJanzen); 30.4mi S Camayagiiela
(D.HJanzen); 30.5mi S Camayagiiela, 930m
(D.HJanzen); Ocotepeque: 2.3mi E [Nueva]
Ocotepeque, 1090m (D.HJanzen); Nueva
Ocotepeque, 910m (D.HJanzen); Santa Barbara:
13.7mi SW Quimistan, 320m (D.HJanzen); Valle:
18.5mi W Jicaro Galan (D.HJanzen); 4.6mi E
Jicaro Galan, 190m (D.HJanzen).
MEXICO Camp.: O.lmi S Tenabo, rd. to Becal
(D.HJanzen); 0.8mi E Campeche (D.HJanzen);
29mi E & 12mi S Campeche (Ruinas Edzna)
(D.HJanzen); 29mi E Campeche (D.HJanzen);
48mi NE Puerto Real (Isla Aguada), Hwy.l 80
(D.HJanzen); 5mi S Tenabo (Campeche-Becal Rd.)
(D.HJanzen); Campeche (N.L.H.Krauss); Chis.:
2.4mi E Chiapa de Corzo, Hwy.190, 580m
(D.HJanzen); 2kmN Yxhuatan [Ixhuatan], "2miN
Tapilula" (D.HJanzen); 32mi W [San] Cristobal
de las Casas, Hwy.190 (D.HJanzen); 3km ENE
Chiapa de Corzo, 500m (P.S.Ward); 3mi N Soyalo
[on Hwy.195] (D.HJanzen); 42.5mi S Comitan,
Hwy.190, 680m(D.HJanzen); 5.4mi E Chiapa de
Corzo, Hwy.190, 770m (D.HJanzen); 56.9mi NE
[NW?] Tapachula [on Hwy.200?] (D.HJanzen);
7.0mi NE [NW?] Tapachula [on Hwy. 200?]
(D.HJanzen); 7.5mi NW Cd. Cuauhtemoc,
Hwy.190 (D.HJanzen); 8.5mi S La Trinitaria,
Hwy. 190 (D.HJanzen); FincaEsmeralda (R.Nettel
F.); Puerto de San Benito [=Puerto Madero]
(R.Nettel F.); Tonala, 40m (D.HJanzen); Yerba
Santa (G.N.Collins); Hgo. : 2km W Orizatlan, 245m
(W.MacKay); Oax.: 11.4-17.0mi W Tehuantepec
(D.HJanzen); 19km N San Pedro Pochutla, 200m
(W.MacKay); 3.9mi E Tehuantepec (D.HJanzen);
5.7mi W "Tapanapec" [=Tapanatepec]
(D.HJanzen); 6.0mi E Niltepec ,Hwy.l90, 100m
(D.HJanzen); 8.1ml W Niltepec, Hwy.190, 60m
(D.HJanzen); Temascal (D.HJanzen); Temascal,
25m (D.HJanzen); Q.Roo: 12.2mi S Peto, Q.Roo-
Yucatan border (D.HJanzen); 26.6mi S Felipe
Carillo Puerto (D.HJanzen); 5.4mi E Polyuc
(D.HJanzen); Cancun (A.Dejean); Cenote de Las
Ruinas, 8km NW Polyuc (J.Red et al.); Chetumal
(J.C. & D.Pallister); San Miguel, Cozumel I.
(N.L.H.Krauss); Sian Ka' an (A.Dejean); Sian Ka' an
Reserve, nr. Felipe Carillo Puerto (A.Dejean);
S.L.P.: 2mi N Rio Amahac, Tamazunchale, 400ft.
(W.S.Creighton); 6mi NW Tamazunchale,
600ft.(Univ.Kansas Mex.Exped.); 8mi W San
Joachin (W. J.Gertsch); El Bonito, 7mi S Cd. Valles,
VOLUME 2, NUMBER 1, 1993
149
300ft. (P.H. & M. Arnaud); El Salto (W.E.LaBerge);
Tamazunchale (D.H.Janzen); Tamazunchale, 600ft.
(W.S.Creighton); Ver.: 29.5mi NW Tuxpan,
Hwy. 122 [actually Hwy. 127] (D.H.Janzen); Alazan
(F.Parker & D.Miller); Cordoba (W.M.Mann);
CotaxtlaExp. Sta.,Cotaxtla (D.H.Janzen); Mirador
(E.Skwarra); Veracruz (E.Skwarra); Yuc.: 30mi S
Merida (P.J.Spangler); 8mi E Merida (rd. to Pto.
Juarez) (D.H.Janzen); Itzimna (J.C. &
D.Pallister);Merida (D.H.Janzen; N.L.H.Krauss);
Oxkutzcab (D.H.Janzen); Sta. Elena, S of Ticul,
"Hwy.180" [prob.Hwy.261] (D.H.Janzen); state
unknown: "Mex"("Norton").
NICARAGUA Estelt: Imi N Condega, 500m
(D.H.Janzen); 2.5mi N Condega, 620m
(D.H.Janzen); Leon: San Jacinto (J.M.Maes);
Madriz: 3mi W Somoto, 650m [=2.5mi W Somoto]
(D.H.Janzen); Nueva Segovia: 7. Imi W Amatillo
(D.H.Janzen).
Pseudomyrmex satanicus (Wheeler 1942)
(Figs. 10, 20, 59, 68)
Pseudomyrma satanica Wheeler 1 942: 1 74. Syntype
workers, queen, male, Rio Agua Salud, Canal
Zone, Panama (W. M. Wheeler) (AMNH,
LACM, MCZC) [Examined]. One MCZC
syntype worker here designated LECTOTYPE.
Pseudomyrmex satanica [sic] (Wheeler); Janzen
1966:252.
Pseudomyrmex satanicus (Wheeler); Kempf
1972:223.
Worker measurements (n= 15). HL 1.16-1.36,
HW 1.10-1.26, MFC 0.035-0.057, CI 0.90-0.97,
REL 0.45-0.50, REL2 0.48-0.52, OOI 0.92-1.67,
VI 0.69-0.78, FCI 0.030-0.049, SI 0.45-0.49, SI2
0.88-1 .00, NI 0.63-0.68, PLI 0.47-0.54, PWI 0.46-
0.63, PPWI 1.35-1.54.
Worker diagnosis. Similar to P. spinicola (q.v.)
except as follows. Larger (HW > 1 .09), head broader
(CI > 0.88) (Fig. 34) with straight or slightly con-
cave posterior margin and subangulate posterolat-
eral corners (Fig. 10). (The posterior margin of the
head approaches this condition in some P. spinicola
workers but these have much smaller, more elon-
gate heads, HW < 1 . 10, CI < 0.90.) Median clypeal
lobe narrower (CLW/HW 0.20-0.22; see Fig. 33).
Palp formula 4,3. Head with pronounced pit-like
impression below the median ocellus (absent or
poorly developed in P. spinicola). Metanotal groove
better developed, longer. Petiole tending to be
more slender, with less distinct posterolateral cor-
ners (this characteristic seen in some workers of P.
spinicola, especially individuals from Panama).
Body pubescence averaging thicker than in P.
spinicola. Dark brown in color, mandibles and
appendages lighter.
Comments. The foregoing diagnosis will al-
low discrimination of P. satanicus workers from
those of the closely related P. spinicola; queens can
be recognized by size alone (HL > 1.65, HW >
1.20). P. satanicus can be distinguished from the
remaining members of the P.ferrugineus group by
the emarginate, laterally angulate median clypeal
lobe of the worker and the large size of the queen.
Distribution and biology. P. satanicus is a
forest species restricted to a few localities in central
Panama where its host plant, Acacia melanoceras,
grows (Fig. 68). Both the ant and plant are intoler-
ant of forest clearance and are considered vulner-
able to extinction (Janzen 1974). The ant is polygy-
nous, with 5-20 or more queens per colony, and the
workers are particularly aggressive, even for aca-
cia-ants (Wheeler 1942; Janzen 1974). See Janzen
(1974:43-53) for additional details on P. satanicus
and its host plant.
Material examined (AMNH, LACM, MCZC,
PSWC, USNM).
PANAMA Canal Zone: "Canal Zone"
(A.H.Jennings); 3miSWGatun Dam (D.H.Janzen);
Barro Colorado Island (D.H.Janzen); France Field
(G.C. Wheeler); Marajal [Majagual] nr. Colon
(W.M. Wheeler); Red Tank (W.M.Wheeler); Rio
Agua Salud (W.M.Wheeler); Zorra Island
(D.H.Janzen); Panama: Rio Piedras (D.H.Janzen);
prov. unknown: "Panama"(c.u.).
Pseudomyrmex spinicola (Emery 1 890)
(Figs. 11,21,60,68)
Pseudomyrma spinicola Emery 1890:64. Lecto-
type worker, Alajuela, Costa Rica (Alfaro)
(MCSN) [Examined].
Pseudomyrma spinicola race atrox Forel 1912:24.
150
JOURNAL OF HYMENOPTERA RESEARCH
Syntype workers, Panama (Christophersen)
(MHNG, NHMB) [Examined]. Syn. nov. One
syntype from MHNG here designated LECTO-
TYPE.
Pseudomyrma spinicola race Gaigei Forel
1914:615. Syntype workers, Columbien (Gaige)
(MHNG), Fundacion, Colombia (F. M. Gaige)
(LACM, MCZC) [Examined]. Syn. nov.
Pseudomyrma spinicola subsp. infernalis Wheeler
1942:180. Syntype workers, queens, males,
Venado, Canal Zone, Panama (W. M. Wheeler),
Red Tank, Canal Zone, Panama (W. M. Wheeler),
and Las Sabanas, Panama (W. M. Wheeler)
(AMNH, MCZC) [Examined]. One MCZC
worker, from Red Tank, here designed LECTO-
TYPE. Syn. nov.
Pseudomyrma spinicola subsp. scelerosa Wheeler
1942:181. Syntype workers, Granada, Nicara-
gua (C. F. Baker) (AMNH, MCZC) [Exam-
ined] . One MCZC worker here designated LEC-
TOTYPE. Syn. nov.
Pseudomyrma spinolae [sic] var. infernalis
Enzmann 1945:91. Syntype workers, queens,
Red Tank, Canal Zone, Panama (W. M. Wheeler)
(MCZC) [Examined] [Objective synonym of P.
spinicola subsp. infernalis Wheeler; Brown
1949:43].
Pseudomyrma spinolae [sic] var. scelerosa
Enzmann 1945:91. Syntype workers, Granada,
Nicaragua (C. F. Baker) (MCZC) [Examined]
[Objective synonym of P. spinicola subsp.
scelerosa, Wheeler; Brown 1949:43].
Pseudomyrmex spinicola (Emery); Wheeler and
Wheeler 1956:386.
Worker measurements (n = 41). HLO.99-1.28,
HW 0.94-1.15, MFC 0.032-0.067, CI 0.84-0.97,
REL 0.42-0.47, REL2 0.45-0.54, OOI 1.22-2.77,
VI 0.64-0.83, FCI 0.032-0.061, SI 0.45-0.50, SI2
0.88-1.05, NI 0.61-0.69, PLI 0.47-0.64, PWI 0.49-
0.71, PPWI 1.32-1.85.
Worker diagnosis. Median clypeal lobe emar-
ginate, laterally angulate (Fig. 11), relatively broad
(CLW/HW 0.21-0.25). Palp formula 5,3 (rarely
5p4,3). Frontal carinae relatively close, and me-
dian lobes of antennal sclerites rather exposed
(FCI2 0.24-0.42). Head longer than broad but
variably so (see range of CI values). Posterior
margin of head ranging from broadly convex (Fig.
11) to straight or even weakly concave, usually
rounding gently into the sides of head. Basal face
of propodeum subequal to declivitous face, round-
ing into latter; in dorsal view propodeal spiracles
salient,protruding laterally. Petiole generally slen-
der (PLI <0.65) with a well developed anterior
peduncle; in dorsal view posterolateral angles typi-
cally prominent. Head densely punctulate, sublucid,
interspaces small (punctulae essentially contigu-
ous on most of head) but shiny. Mesosoma finely
punctulate dorsally becoming punctulate-coriarious
laterally, sublucid; propodeum lacking overlying,
coarser rugulo-punctate sculpture. Standing pilos-
ity usually moderately common on body dorsum
and including some hairs > 0.20 mm. Appressed
pubescence common on most surfaces. Varying
from light orange-brown to dark brown in color.
Comments. The short, broad, emarginate and
laterally angulate median clypeal lobe (Fig. 11)
distinguishes the worker of this species. The
sublucid integument, elongate petiole, prominent
propodeal spiracles, and somewhat angulate poste-
rolateral corners of the petiole are also characteris-
tic. In addition, queens and workers of P. spinicola
have more elongate scapes and legs than those of all
other species except P. satanicus(Figs. 30,31). For
differences between P. spinicola and the closely
related P. satanicus see under the latter species.
P. spinicola is a variable taxon and has received
several infraspecific names, here considered junior
synonyms. Southeastern populations (from the Rio
Grande de Tarcoles in Costa Rica east through
Panama to northern Colombia) are somewhat dif-
ferentiated from the others, with the workers and
queens tending to have more elongate heads, darker
color, and more slender petioles with less pro-
nounced posterolateral angles (see Figs. 34, 35). In
Costa Rica the contrasts between the two sets of
populations are rather striking, and are perhaps
accentuated by habitat differences since some (but
not all) the southeastern populations are associated
with Acacia allenii growing in forested situations,
while the northern populations are primarily from
Acacia collinsii in open habitats. Samples from
Panama (all associated with A. collinsii) are more
variable and partly bridge the phenotypic gap. It is
possible that more than one species is masquerad-
VOLUME 2, NUMBER 1, 1993
151
ing in this variation but the evidence remains am-
biguous.
Distribution and biology. P. spinicola is a
monogynous species, distributed from Honduras to
northern Colombia (Fig. 68), which is associated
with Acacia collinsii and, less frequently, Acacia
allenii and A. cornigera. Janzen (1983) provides a
good summary of its biology in Costa Rica, under
the name "P. ferruginea". Observations on "P.
ferruginea" in Costa Rica, Nicaragua, Panama and
Isla Providencia (Janzen 1969, 1974, 1975, 1983)
refer to P. spinicola', true P. ferrugineus does not
occur south of Honduras and El Salvador.
Material examined (AMNH, ANSP, BMNH,
CUIC, FFIC, GBFM, GCWC, INBC, JTLC, KSUC,
LACM, MCSN, MCZC, MHNG, MZSP, NHMB,
PSWC, UCDC, USNM).
COLOMBIA Atlantico: Cuatro Bocas, 200m
(J. F.G.Clarke); Bolivar. Hda. Monterey, 50m
(G.Fagua; F.Fernandez); Magdalena: Aracataca
(P.J.Darlington); Fundacion (F.M.Gaige);
Fundacion, Santa Marta Mts.,300ft. (F.M.Gaige);
San Andres y Providencia: "Old Providence Isl."
(D.Fairchild); Isla Providencia, 300ft.(D.H.Janzen);
dept. unknown: "Columbien" (Gaige).
COSTA RICA Alajuela: Alajuela (A.Alfaro);
San Mateo (P.Biolley); Surubres, nr. San Mateo
(P.Biolley); Turriicares (A.Alfaro); Cartago:
Turrialba (c.u.); Guanacaste: 10.7mi NW Liberia
(D.H. Janzen); 2mi S Canas (D.H. Janzen); 5km S
Liberia (D.H.Janzen); 6mi W Liberia (D.H.Janzen);
7km N Canas (D.H.Janzen); Canas, "La Pacifica"
(R.L.Jeanne); Finca La Pacifica (D.W.Davidson);
Garita (A.Alfaro) ; Hda. Comelco, 24km NW Canas
(InterAm Hwy) (E.R.Heithaus); Hda. La Pacifica,
nr. Canas, 50m (P.S.Ward); Palo Verde (D.E.Gill;
E.Guerrant & P.Fiedler; H.A.Hespenheide;
D.H. Janzen) ;Palo Verde, 50m (D.M.Olson); Palo
Verde, < 1 00m (J.Longino) ; Rio Corobici, nr. Canas
(R.M.Bohart); Santa Rosa Natl. Pk.(E.M.Barrows);
SantaRosaNatl.Pk.,300m(J.Longino;P.S.Ward);
Santa Rosa Natl. Pk., 5m (P.S.Ward); Santa Rosa
Natl. Pk., <5m (P.S.Ward); Heredia: "15mi SE
Pto.Viejo" [15km SW Pto.Viejo] (D.H.Janzen);
Puntarenas: l-5mi NW Rincon (D.H.Janzen);
14.1mi N Golfito (D.H.Janzen); 14km E Palmar
Norte, 70m (P.S.Ward); 1km NE Tarcoles, 20m
(P.S.Ward); 21.6 rd.mi NE Palmar Norte, 90m
(D.H.Janzen); 3.4miSEGolfito, 30m (D.H.Janzen);
4mi SW Rincon (D.H.Janzen); Corcovado Natl.
Pk. (D.W.Davidson; J.T.Longino); Corcovado Natl.
Pk., Llorona (J.T.Longino); Corcovado Natl. Pk.,
Sirena, 100m (P.S.Ward); Corcovado Natl. Pk.,
Sirena, 10m (P.S.Ward); Entrada Boruca, 20km
NE Palmar Sur (D.H.Janzen) ; Osa Penin., nr. Rincon
(D.H.Janzen); Reserva Biol. Carara, 30m
(P.S.Ward);Rincon (D.H.Janzen); Rio Terraba, nr.
Palmar Sur (D.H.Janzen); San Jose: 16.4mi SW
Sanlsidro, 160m (D.H. Janzen); 3. 5km NE Santiago
de Pur (D.H.Janzen); Santa Ana (D.H.Janzen);
Tarrazu [Rio?] (A.Alfaro); Villa Colon (A.Alfaro;
D.H.Janzen); Villa Colon, 880m (A.Alfaro).
HONDURAS Choluteca: 1 1 . 1 mi NE Choluteca,
450m (D.H.Janzen); 3.6mi W Choluteca, 200m
(D.H.Janzen); Colon: El Canal, Puerto Castilla
(W.M.Mann); Roetan Isl. [Isla de Roatan]
(M.Bates); Trujillo, 80m (Echternacht).
NICARAGUA Boaco: Empalme do Boaco
[=ElEmpalme?] (Echternacht); Chontales: no spe-
cific locality (Janson); Esteli: 7.5mi NW San Isidro,
550m (D.H.Janzen); Granada: Granada
(C.F.Baker); Leon: 19mi SE Leon [=3.5mi N
Pto.Somoza (Sandino)] (D.H.Janzen); 28.1mi SE
Leon (D.H.Janzen); Madriz: 13.9mi from Hondu-
ras, on Nic.border, Hwy.l (D.H.Janzen); 2.5mi W
Somoto (D.H.Janzen); Managua: 20mi N Tipitapa,
90m [=19.4mi N Tipitapa] (D.H.Janzen); 8.1mi E
San Benito (D.H.Janzen); 9mi N Tipitapa, 50m
[=8.8mi N Tipitapa] (D.H.Janzen); Matagalpa:
15.8mi NW Sebaco (D.H.Janzen); 2.6mi N Dario
(D.H.Janzen); 4.1mi S Matagalpa, 650m
(D.H.Janzen); 4mi S Dario, 350m [=4.5mi SE Dario]
(D.H.Janzen); 4mi S Dario, 350m (D.H.Janzen);
Rivas: C.R. border, Imi N Penas Blancas, <5m
[=lmi NW Penas Blancas] (D.H.Janzen); Isla
Ometepe (F.Joyce); San Juan del Sur, 10m [=lmi N
San Juan del Sur] (D.H.Janzen).
PANAMA Canal Zone: 7.5mi NW Balboa
(between Summit Gdn. &Paraiso) (D.H.Janzen);
Ancon (S.F.Blake); Barro Colorado Island (We-
ber); Cerro Galera (P.S.Ward); Chivachiva trail
(W.M.Wheeler); Chivachiva trail, nr. Red Tank
(W.M.Wheeler); Culebra [presumably CulebraCut]
(D.D.Gaillard); E end of Madden Dam
(D.H.Janzen); Gamboa (N.Banks); Howard AFB,
152
JOURNAL OF HYMENOPTERA RESEARCH
W of Panama City, 50m (W.L.Brown et al.); Mad-
den Dam (D.Quintero et al.); Paraiso (A.Busck);
Red Tank (W.M. Wheeler); Ruta 1, 14kmWPanama
City, 100m (W.L.Brown et al.); Venado
(W.M. Wheeler); W end Madden Dam
(D.HJanzen); Chiriqui: 10.7mi ESE Concepcion
(D.H.Janzen); 12.9mi E Remedies (D.HJanzen);
19.6mi E Sapotilla, 50m (D.HJanzen); 7.2mi W
Remedies (D.HJanzen); 9.5mi S Boquete, 620m
(D.HJanzen); Code: 0.3mi W Agua Dulce, 50m
(D.H.Janzen); 10.4miNE SantaMaria, 60m [=1 .9mi
W Agua Dulce, Hwy. 1] (D.HJanzen); 2.7mi SW
Penonome (D.H.Janzen); Herrera: Cerro
Guacamaya, Albina al N. de Monagrillo (D.Quintero
et al.); Los Santos: 3.1mi N Pedasi (D.HJanzen);
Azuero Penin., 5.4mi SE Los Santos, <5m
(D.H.Janzen); Panama: 18.6mi SW Chepo
(D.HJanzen); Bella Vista (N.Banks); Las Sabanas
(G.C.Wheeler; W.M.Wheeler); Las Sabanas,
Panama City (H.F.Dietz); Rio Corona, S of El
Valle, 2000ft. (C.W.Rettenmeyer); Rio Tetita, San
Carlos (F.D.Rattinibane); savannah nr. Juan Diaz
(Weber); Veraguas(l): LasPalmas (c.u.); Veraguas:
4km NW Santiago (D.Quintero); prov. unknown:
"Panama" (Christophersen).
Pseudomyrmex veneficus (Wheeler 1942)
(Figs. 17, 28, 62, 69)
Pseudomyrma belli subsp. venefica Wheeler
1942:162. Syntype workers, males, queens,
Escuinapa, Sinaloa, Mexico (J. H. Batty)
(AMNH, MCZC) [Examined]. One MCZC
syntype worker here designed LECTOTYPE.
Pseudomyrma belli subsp. venifica Enzmann
1945:81. Syntype workers, queens, Manzanillo,
Colima, Mexico (C. H. T. Townsend) (MCZC)
[Examined] [Synonymy by Brown 1949:42].
Pseudomyrmex venefica [sic] (Wheeler); Janzen
1969:241.
Pseudomyrmex belli veneficus (Wheeler); Kempf
1972:216.
Pseudomyrmex veneficus (Wheeler); Ward
1989:439.
Worker measurements (n= 12). HLO.95-1.04,
HW 0.85-0.95, MFC 0.045-0.073, CI 0.88-0.95,
REL 0.44-0.47, REL2 0.47-0.52, OOI 1.26-2.30,
VI 0.66-0.75, FCI 0.051-0.081, SI 0.43-0.46, SI2
0.85-0.94, NI 0.58-0.65, PLI 0.60-0.67, PWI 0.58-
0.67, PPWI 1.35-1.73.
Worker diagnosis. Similar to P. ferrugineus
(q.v.) except as follows. Smaller (LHT 0.69-0.80),
with broad head (CI > 0.87); frontal carinae sepa-
rated by basal scape width or less (FCI2 0.40-0.60);
petiole short (PL 0.43-0.54) and relatively narrow
(see PWI values) with somewhat rounded postero-
lateral angles (Fig. 28). Head densely punctulate,
subopaque to sublucid, with weak silvery reflec-
tance. Overlying rugulo-punctate sculpture on
propodeum weak and ill-defined. Standing pilosity
variable in abundance, becoming rather short (
0.10 mm) and sparse in southern populations. Pu-
bescence thick and conspicuous, suberect on some
surfaces especially the propodeum and petiole;
suberect pubescence on petiolar dorsum contrast-
ing with the appressed pubescence on the postpetiole
(Fig. 28). Very dark greyish-brown to black, parts
of the mesosoma and petiole sometimes with lighter
yellowish brown (more consistently so in the queen).
Comments. The small size (worker HW < 0.96;
queen HW 0.84-0.96, n=12), conspicuous suberect
pubescence on the propodeum and petiole, and
black coloration of the head and gaster distinguish
workers and queens of P. veneficus. The related
species, P. flavicornis, is larger (worker HW >
0.98, queen HW 1.12-1.19) with a broader and
more robust petiole (Figs. 25, 28). Workers and
queens of P. flavicornis also lack the sublucid head
and conspicuous suberect pubescence characteris-
tic of P. veneficus. P. mixtecus is somewhat inter-
mediate between these two - it has the head sculp-
ture and pubescence typical of P. flavicornis but
approaches P. veneficus in size (worker and queen
head widths overlapping, although only slighter in
the queens where HW 0.96-1.01 (n=8) in P.
mixtecus) and petiolar dimensions (Figs. 44-47).
Distribution and biology. P. veneficus has a
limited distribution in western Mexico (Sinaloa to
Michoacan) (Fig. 69) where colonies occupy Aca-
cia hindsii and, at one locality, A. collinsii. Janzen
(1973) gives a detailed description of the ecology
and behavior of this highly polygynous, effectively
unicolonial, species whose colonies are among the
largest of all social insects (containing millions of
workers and several hundred thousand queens).
VOLUME 2, NUMBER 1, 1993
153
Material examined (AMNH, CASC, EBCC,
INKS, LACM, MCSN, MCZC, MZSP, PSWC,
UCDC, UCRC, USNM).
MEXICO Col: 9 Ami NW Manzanillo
(D.H.Janzen); Manzanillo (C.H.T.Townsend;
W.M.Wheeler); Paso del Rio, 200ft. (IJ.Cantrall);
JaL: 2km E Chamela, 20m (P.S.Ward); 5km E
Chamela, 50m (P.S.Ward); 6mi NE El Rincon,
1600ft. (R.J.Hamton); Barra de Navidad
(N.L.H.Krauss); Chamela (RJ.McGinley;
J.F.Watkins);M/c/z.: 1.1 mi N Gabriel Zamora, 820m
(D.H.Janzen); 1.5miNLaMira (D.H.Janzen); 15km
WNW Playa Azul, 50m (P.S.Ward); Nay.: 12mi
NE San Bias (W.J.Gertsch & W.Ivie); 16mi NW
Tepic (W.E.LaBerge); 3 Imi N Tepic (D.H.Janzen);
37mi N Tepic (D.H.Janzen); 4mi E San Bias
(M.E.Irwin); Rio Palillo, 14mi E San Bias
(D.H.Janzen); Sin.: 14.6mi S Mazatlan
(D.H.Janzen); 20mi E Villa Union (E.I.Schlinger);
20mi E Villa Union, 235m (M.E.Irwin; E.Schlinger
et al.); 20mi S Villa Union (E.I.Schlinger); 5mi E
Concordia (W.J.Gertsch & J.A.Woods); Escuinapa
(J.H.Batty); Palmito (L.de Mauzo); Piedra Blanca
(R.M.Bohart); state unknown: "Mexico"(c.u.).
OTHER ACACIA-ASSOCIATED
ferrugineus group
spimcola
V spinicola + satanicus
satanicus
Figs. 67- 72. Distributions of species in the Pseudomyrmex ferrugineus group.
154
JOURNAL OF HYMENOPTERA RESEARCH
PSEUDOMYRMEX
FROM CENTRAL AMERICA
Introduction
Three of the species discussed below
(Pseudomyrmex nigropilosus, P. simulans and P.
subtilissimus) are obligate inhabitants of Central
American swollen-thorn acacias, although they are
not closely related to the P. ferrugineus group
(Ward 1991). A fourth species, P. reconditus, is
known only from a single collection, made in
association with Acacia collinsii. The remaining
six species (P. boopis, P. gracilis, P. hesperius, P.
ita, P. kuenckeli and P. opaciceps) are non-special-
ist Pseudomyrmex which have been collected only
occasionally from acacias. These taxa are included
for completeness, and their presentation here ne-
cessitates a certain amount of taxonomic house-
cleaning.
One could expect additional generalist
Pseudomyrmex to be found in living or dead acacia
thorns. Menozzi (1927b) mentions collections by
H. Schmidt of "Pseudomyrma flavidula" and "P.
brunnea" from Acacia "spadicigera" (probably A.
collinsii) near San Jose, Costa Rica. I have not
examined the ant specimens in question but they
probably belong to P. pallidus (F. Smith) and P.
ejectus (F. Smith), respectively. Diagnoses of these
species appear in Ward (1985). Finally, mention
should be made of other Neotropical acacias which
are apparently not myrmecophytes, but which may
harbor opportunistic Pseudomyrmex species in their
spines: Acacia daemon in Cuba with P. pazosi, P.
simplex and P. cubaensis (Berazain & Rodriguez
1983; Pseudomyrmex nomenclature follows Ward
1989), and A. coven in Paraguay with P. gracilis
(s.l.) and one or more species in the P. pallidus
group (Wheeler 1942; Ward 1991).
Synonymic list of species
P. boopis (Roger 1863b)
= P. modestus (F. Smith 1862) (preoccupied)
= P. thoracicus (Norton 1868b) syn. nov.
= P. excavatus (Mayr 1870) (Kempf 1967)
= P.flaviventris (Emery 1896) (Kempf 1960)
= P.fusciceps (Santschi 1931) (Kempf 1960)
= P. guatemalensis (Enzmann 1945) (Kempf
1960)
P. gracilis (Fabricius 1804)
= P. bicolor (Guerin 1844) syn. nov.
= P. sericatus (F. Smith 1855) syn. nov.
= P. dimidiatus (Roger 1863a) syn. nov.
= P. mexicanus (Roger 1863a) syn. nov.
= P. variabilis (F. Smith 1877) (Ward 1989)
= P. pilosulus (F. Smith 1877) syn. nov.
= P. volatilis (F. Smith 1877) syn. nov.
= P. canescens (F. Smith 1877) syn. nov.
= P. guayaquilensis (Forel 1907) (unavailable
name)
= P. glabriventris (Santschi 1922) syn. nov.
= P. veliferus (Stitz 1933) syn. nov.
= P. longinodus (Enzmann 1945) (Brown 1949)
P. hesperius, sp. nov.
P. ita (Forel 1906) stat. nov.
= P. acaciarum (Wheeler 1942) syn. nov.
= P. acaciorum (Enzmann 1945) (Brown 1949)
P. kuenckeli (Emery 1890)
= P. dichrous (Forel 1904) (Kempf 1961)
= P. bierigi (Santschi 1932) (Kempf 1961)
= P. crenulatus (Enzmann 1945) (Kempf 1961)
P. nigropilosus (Emery 1890)
P. opaciceps, sp. nov.
P. reconditus, sp. nov.
P. simulans Kempf 1958
P. subtilissimus (Emery 1890)
SPECIES ACCOUNTS
Pseudomyrmex boopis (Roger 1863b)
(Fig. 1)
Pseudomyrma modesta F. Smith 1862:32. Holo-
type (unique syntype) worker, Panama (Stretch)
(BMNH) [Examined]. [Preoccupied by P.
modesta F. Smith 1 860 = Tetraponera modesta
(F. Smith).]
Pseudomyrma boopis Roger 1863b:25. Replace-
ment name for Pseudomyrma modesta.
Pseudomyrma thoracica Norton 1868b:8. Syntype
workers, Cordova, Mexico (Sumichrast) [Not
examined; see comments below]. Syn. nov.
Pseudomyrma excavata Mayr 1870:410. Syntype
workers, "N. Granada" (BMNH, MHNG,
NHMV) [Examined] [Synonymy by Kempf
VOLUME 2, NUMBER 1, 1993
155
1967:2].
Pseudomyrma excavata var. flaviventris Emery
1896:2. Syntype workers, Darien, Panama
(Festa) (MCSN, MHNG) [Examined] [Syn-
onymy by Kempf 1960:22].
Pseudomyrma excavata var. fusciceps Santschi
1931:271. Two syntype workers, France Field,
Panama (A. Bierig) (NHMB) [Examined] [Syn-
onymy by Kempf 1960:22].
Pseudomyrma spinicola subsp. modesta F. Smith;
Wheeler 1942: 105.
Pseudomyrma tenuis var. guatemalensis Enzmann
1945:92. Holotype worker, Escuintla, Guate-
mala [Not examined] [Synonymy by Kempf
1960:22].
Pseudomyrmex boopis (Roger); Kempf 1967:2.
Worker diagnosis. Medium-sized species (HW
1 . 1 6- 1 .29) in the P. tenuis group, with a broad head
(CI 0.92-1.02), tectiform and laterally rounded
median clypeal lobe, large eyes (REL 0.66), and
laterally marginate pronotum. Mesosoma arched
and angular in profile; petiole short, high and thin,
laterally marginate, with a gently ascending
anterodorsal face which rounds into a much steeper
(almost vertical) posterior face (Fig. 1). Standing
pilosity sparse, lacking on the mesonotum,
propodeum, and petiole. Color highly variable,
ranging from light testaceous brown to bicolored
orange and black (usually with the gaster and
pronotum lightest in color) to dark brown.
Taxonomic comments. For a more detailed
description of this species see Kempf (1960:23). I
have synonymized P. thoracicus (Norton) under P.
boopis on the basis of Norton's (1868b) original
description and the biological notes of Sumichrast
in Norton (1868a). In combination these clearly
suggest P. boopis rather than any other
Pseudomyrmex known to occur in southern Mexico.
Although the type material of P. thoracicus is
presumably lost, additional indirect evidence of its
identity can be found in Gustav Mayr's collection
in Vienna (NHMV) where there is a P. boopis
worker from Colombia ("Neugranada") identified
by Mayr as "P. thoracica Norton". This take son
added significance when it is realized that Mayr
was apparently the recipient of some of Norton's
material. During a brief visit to NHMV I noted
specimens of several species, including P.
ferrugineus, P. peperi, P. elongatulus (Dalla Torre)
and P. brunneus (F. Smith) (although unfortunately
not P. boopis), labelled "Mex. Norton" or "N. Am./
Norton".
Distribution and biology. P. boopis occurs in
rainforest and tropical moist forest from southern
Mexico to Ecuador, Venezuela and northern Brazil.
This species is less arboreal than most
Pseudomyrmex, and nests typically in rotten wood
on or near the ground. The type specimen of P.
boopis came from a nest in a swollen-thorn acacia
(Smith 1862:33), however, and Janzen found colo-
nies in thorns of Acacia melanoceras seedlings in
Panama.
Pseudomyrmex gracilis (Fabricius 1 804)
(Fig. 6)
Formica gracilis Fabricius 1804:405. Lectotype
worker, Essequibo, Guyana (ZMUC) [Exam-
ined].
Pseudomyrma bicolor Guerin 1844:427. Syntype
queen (unique?), Colombia (ZSMC) [Exam-
ined] Syn. nov.
Pseudomyrma sericata F. Smith 1855:159. Holo-
type (unique syntype) worker, Brazil (BMNH)
[Examined] Syn. nov.
Pseudomyrma dimidiataRoger 1863a:177. Syntype
workers, Colombia (not in MNHN or ZMHB)
[Not examined] Syn. nov.
Pseudomyrma mexicana Roger 1863a: 178. Syntype
workers, Mexico (not in MNHN or ZMHB)
[Not examined] Syn. nov.
Pseudomyrma variabilis F. Smith 1877:62. Lecto-
type worker, Barbadoes (BMNH) [Examined]
[Synonymy by Ward 1989:439].
Pseudomyrma pilosula F. Smith 1877:62. Two
syntype workers, Barbadoes (BMNH) [Exam-
ined]. One syntype here designated LECTO-
TYPE. Syn. nov.
Pseudomyrma volatilis F. Smith 1877:65. Holo-
type (unique syntype) male, Mexico (BMNH)
[Examined] Syn. nov.
Pseudomyrma canescens F. Smith 1877:66. Holo-
type (unique syntype) queen, Abydos, Brazil
(BMNH) [Examined] Syn. nov.
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JOURNAL OF HYMENOPTERA RESEARCH
Pseudomyrma gracilis var. glabriventris Santschi
1922:345. Syntype workers, Izozo, Bolivia (Lizer
& Deletang) (NHMB) [Examined] Syn. nov.
Pseudomyrma gracilis mexicana var.
guayaquilensis Forel 1907:7. Worker,
Guayaquil, Ecuador (Buchwald) (MHNG) [Ex-
amined] Unavailable infrasubspecific name.
Pseudomyrma gracilis var. velifera Stitz 1933:68.
Holotype queen, Champerico, Guatemala
(Paessler) (not in ZMUH; Weidner 1972) [Not
examined] Syn. nov.
Pseudomyrma gracilis var. longinoda Enzmann
1945:87. Syntype worker, Peru (MCZC) [Ex-
amined] [Synonymy by Brown 1949:43].
Pseudomyrmex gracilis (Fabricius); Kusnezov
1953:214.
Worker diagnosis. With the traits of the gracilis
group (see couplet 6 of the key; p. 130) and the
following more specific features. Head broad, about
as wide as long (CI 0.95-1.08); anterior margin of
median clypeal lobe straight to broadly convex,
rounded laterally; pronotum dorsolaterally margin-
ate but not sharply so; in lateral view mesonotum
more steeply inclined than basal face of propodeum;
petiole long and slender (PLI 0.46-0.57) with a
distinct anterior peduncle (Figs. 6, 53); head densely
punctulate with a subopaque to sublucid (not matte)
appearance; standing pilosity abundant, fine, pre-
dominantly pale silvery- white (not black).
Size and color extremely variable (HW 1.39-
2.07), varying from unicolorous black (appendages
lighter) to unicolorous orange-brown, with many
intermediate and bicolored combinations. In popu-
lations from Mesoamerica the gaster is typically
black, or if paler (orange-brown) then it is usually
accompanied by a similar light coloration of the
mesosoma (and sometimes also the head).
Taxonomic comments. The P. gracilis com-
plex presents one of the more taxonomically chal-
lenging problems in the genus Pseudomyrmex and
the above treatment is by no means a final solution.
The worker- and queen-based forms, newly syn-
onymized under P. gracilis, fall within the bounds
of the preceding diagnosis, but it is quite possible
that my concept of this species will prove to be too
broad. The types of P. dimidiatus, P. mexicanus and
P. veliferus could not be located. They are judged to
be junior synonyms on the basis of the original
descriptions. The unique male holotype of P.
volatilis is clearly a member of the P. gracilis group
based on size (HW 1.48), mandibular dentition,
pilosity, petiole shape, and shape of the parameres.
In comparison with males of gracilis group species
known to occur in Mexico, namely P. gracilis, P.
major (see below), P. nigropilosusandP. opaciceps,
the type specimen agrees best with P. gracilis.
The concept of P. gracilis adopted above en-
compasses an impressive amount of phenotypic
variability. Collections from single regions often
give the impression that this variation is distributed
bimodally or multimodally , as more or less discrete
morphs. For example, nest samples from Costa
Rica can be segregated on the basis of worker
morphology into (i) a large (HW > 1.80), usually
lighter-colored form (with orange mesosoma, peti-
ole, and postpetiole, and black head and gaster), (ii)
a smaller, bicolored, usually more heavily infuscated
form, and (iii) an all-black form of variable size.
The first two are typically found in open or xeric
habitats while the third is more common in closed
forest, suggesting some ecotypic differentiation.
Yet when large enough sample sizes are obtained
all degrees of intermediacy in size and color are
encountered, and the variation in color (less so size)
can be seen among individuals (workers and alate
queens) from the same nest. Thus, if there are
ecotypes they do not appear to be reproductively
isolated.
Left unresolved after the establishment of the
above synonymy is the relationship of P. gracilis to
the following nominal taxa: P. alternans (Santschi),
P. gracilis atrinodus (Santschi), P. gracilis
argentinus (Santschi) and P. santschii (Enzmann).
But the following deserves recognition as a distinct
species: Pseudomyrmex major (Forel 1899:91),
stat. nov. (syntype worker, Pinos Altos, Chihua-
hua, Mexico (Buchan-Hepburn) (BMNH) (exam-
ined); original combination: Pseudomyrma gracilis
var. major). Workers of P. major can be distin-
guished from those of P. gracilis by their emargin-
ate median clypeal lobe, less distinct anterior pe-
duncle of the petiole, and larger average size. Males
of P. major have broadened fore-tarsal segments.
P. major is confined to western Mexico, where it
occurs sympatrically with P. gracilis without show-
VOLUME 2, NUMBER 1 , 1993
157
ing signs of intergradation.
Distribution and biology. Befitting its wide
distribution (southern United States to Argentina
and Brazil) and variable phenotype, P. gracilis can
be found in a variety of habitats from mangroves
and thorn scrub to rainforest. It is often particularly
common in disturbed situations such as old fields,
roadsides, and secondary forest. Nests are usually
located in dead twigs or small branches, but there
are a substantial number of records of colonies
occupying swollen-thorn acacias in Central America
(Mexico to Panama). In a few localities P. gracilis
is a common acacia inhabitant and under these
circumstances it may exhibit local adaptation and
phenotypic differentiation (see also Wheeler
1942:107). For example, Janzen collected a series
of specimens from Acacia gentlei in Belize (15 mi.
S Santa Elena) which have somewhat distinctive
morphology: the workers are large, dark, abun-
dantly hairy, and possess rather short petioles (PLI
0.55), although none of these features is outside
the total range of variation for the species. Janzen
(1974:98) notes that the workers of this large black
morph have atypically aggressive behavior. Given
the kind of ecotypic variation to which P. gracilis is
prone, it is not surprising to find a tendency of some
populations to specialize on acacias. The ecology
of this species is reminiscent of other animal spe-
cies which show broad ecophenotypic variation,
e.g. fish with trophic polymorphisms (Kornfield et
al. 1982; Grudzien and Turner 1984; Sandlund et al.
1992).
Pseudomyrmex hesperius Ward, sp. nov.
(Fig. 4)
Holotype worker. MEXICO Sinaloa: 15.9 mi.
NE Concordia, Hwy. 40, 600m, 9.vi.l967, D. H.
Janzen XVIII, ex Acacia hindsii (LACM). HW
0.66, HL 0.83, EL 0.36, PL 0.34, PH 0.26.
Paratypes. Same data as holotype: series of 1 1
workers (BMNH, LACM, MCZC, MZSP, PSWC,
USNM).
Additional non-type material. MEXICO
Sinaloa: 14 km. S Mazatlan, 18.vii.1965, R. R.
Snelling, 15 workers (LACM, MCZC, PSWC).
Worker measurements (n=6). HL 0.78-0.85,
HW 0.65-0.69, MFC 0.028-0.043, CI 0.79-0.83,
REL 0.43-0.46, REL2 0.54-0.57, OOI 0.86-1.15,
VI 0.75-0.82, FCI 0.043-0.062, SI 0.48-0.51, SI2
0.87-0.93, FI0.41-0.45,PDI 0.84-0.95, MPI 0.053-
0.066,NI0.54-0.59,PLI0.73-0.77,PWI0.63-0.70,
PPWI 1.41-1.56.
Worker diagnosis. Small species (see above
measurements) with elongate, subrectangular head
and short eyes (REL 0.43-0.46, OI 0.61-0.65).
Masticatory margin of mandible with five teeth, the
fourth tooth (counting from the apex) separated by
a gap of ca. 0.05 mm from the apicobasal tooth;
MD8/MD9 0.70; third and fourth teeth small,
contrasting with the large subapical and apical teeth
(the latter ca. 0.032 and 0.055 mm in length, respec-
tively) ; mesial tooth on basal margin situated slightly
closer to apicobasal tooth than to proximal tooth
(MD4/MD5 0.65); palp formula 5,3; median
clypeal lobe short, its anterior margin straight to
weakly convex, sharply rounded laterally; mini-
mum distance between frontal carinae subequal to
or less than basal scape width; frontal carinae
diverging anteriorly and fusing with the antennal
sclerites; pronotum laterally rounded, without hu-
meral angles; in lateral profile the mesonotum and
basal face of propodeum slightly inclined anteri-
orly, separated by a well developed metanotal groove
(Fig. 4); basal face of propodeum rounding into the
longer declivitous face, the latter somewhat con-
cave in profile; petiole short, apedunculate, shaped
as in Fig. 4, with a prominent triangular antero ventral
tooth; in dorsal view petiole very broad anteriorly
(PWI3 0.59-0.62); postpetiole broader than long,
its anteroventral process small and inconspicuous.
Mandibles finely striate; head punctulate on a
smooth shining background, punctulae separated
by one to several diameters on upper half of head,
becoming denser towards the clypeus; mesosoma
sublucid, with weak punctulate-coriarious sculp-
ture; petiole, postpetiole and gaster shining, with
very fine piligerous punctures. Standing pilosity
common but short (< 0.10 mm) on most parts of
body, lacking on outer faces of tibiae. Appressed
pubescence widely distributed, moderately dense
on abdominal tergite IV. Dark brown; mandibles,
appendages and fronto-clypeal complex tending
towards a lighter brown.
Taxonomic comments. This is a taxonomi-
cally isolated species, not belonging to any of the
158
JOURNAL OF HYMENOPTERA RESEARCH
nine major species groups of Pseudomyrmex (see
Ward 1989).ThesalientfeaturesofP. hesperius are
small size (HW < 0.72), reduced mandibular denti-
tion and palp formula, short truncate median clypeal
lobe, short eyes (especially obvious in lateral view,
such that OI > 0.60), short apedunculate petiole
with a broad attachment to the propodeum (PWI3
0.60), punctulate head sculpture, sublucid integu-
ment, and short standing pilosity. Some of these
traits are shared with two other Mesoamerican
Pseudomyrmex, P. fervidus (F. Smith) and a re-
lated undescribed species, but both of these are
larger (HW > 0.70), with standing pilosity which is
longer and more extensive (present on the outer
faces of the tibiae).
Biology. Although the type specimens of P.
hesperius were collected from Acacia hindsii this
species is not an obligate acacia inhabitant. The
series from 14 km. south of Mazatlan was collected
from dead branches of a woody plant, not Acacia
(R. R. Snelling, pers. comm.).
Pseudomyrmex ita (Forel 1906) stat. nov.
(Fig. 2)
Pseudomyrma sericea var. ita Forel 1906:230.
Syntype workers, San Mateo, Costa Rica (P.
Biolley) (MHNG) [Examined]. One syntype
here designated LECTOTYPE.
Pseudomyrma sericea var. acaciarum Wheeler
1942:176. Syntype workers, Tumba Muerta
Road, Panama (W. M. Wheeler) (LACM,
MCZC) [Examined] Syn. nov.
Pseudomyrma sericea var. acaciorum Enzmann
1945:90. Syntype workers, Tumba Muerta Road,
Panama (W. M. Wheeler) (MCZC) [Examined]
[Objective synonym of Pseudomyrma sericea
var. acaciarum Wheeler; Brown 1949:43].
Pseudomyrmex sericeus ita (Forel); Kempf
1972:223.
Worker diagnosis. A medium-sized member
(HW ca. 0.75-0.98) of the P. sericeus group, with
large elongate eyes (REL 0.65), convex median
clypeal lobe, subcontiguous frontal carinae (MFC
0.02), and palp formula of 6,4. Head longer than
broad (CI 0.85). Basal face of propodeum shorter
than declivitous face and meeting the latter at an
angle. Petiole short, high (PLI > 1.00), with sharp
dorsolateral margins; in profile anterior and dorsal
faces of petiole weakly differentiated, rounding
sharply into the vertical posterior face (Fig. 2).
Body with fine punctulate-coriarious sculpture,
opaque. Standing pilosity very sparse; a pair of
stout setae present on the pronotal humeri, petiole,
and postpetiole. Dark brown-black, with lighter
brown maculation variably present on the pronotum,
petiole, postpetiole, fronto-clypeal complex, and
appendages.
Taxonomic comments. This is one of several
species originally described as "varieties" of P.
sericeus (Mayr). Workers of P. ita can be distin-
guished from those of P. sericeus by the angulate
shape of their petiole, especially in lateral view
(Fig. 2); the petiole of P. sericeus is subtriangular in
profile, with more gently rounded edges.
Distribution and biology. P. ita occurs from
Mexico to Colombia, and typically inhabits dead
twigs or branches of various woody plants. It has
been collected from thorns of Acacia cornigera in
Mexico and A. collinsii in Costa Rica and Panama.
Pseudomyrmex kuenckeli (Emery 1890)
(Fig. 3)
Pseudomyrma kuenckeli Emery 1890:62. Syntype
workers, queens, Alajuela, Costa Rica (A. Alfaro)
(MCSN) [Examined].
Pseudomyrmakuenckelivar. dichroaForel 1904:41.
Syntype workers, Dibulla, Colombia (A. Forel)
(AMNH, BMNH, MCSN, MHNG, NHMB,
USNM) [Examined] [Synonymy by Kempf
1961:402].
Pseudomyrma kuenckeli var. bierigi Santschi
1932:412. Holotype worker, Juan Diaz, Panama
(A. Bierig) (NHMB) [Examined] [Synonymy
by Kempf 1961:402].
Pseudomyrma crenulata Enzmann 1945:84. Holo-
type worker, "Guernavaca", Mexico (not in
MCZC) [Not examined; but other P. kuenckeli
workers in the MCZC from Cuernavaca, Mexico
(Wheeler) evidently represent the source series]
[Synonymy by Kempf 1961:402].
Pseudomyrmex kuenckeli (Emery); Kusnezov
1953:214.
VOLUME 2, NUMBER 1 , 1 993
159
Worker diagnosis. A member of the P. viduus
group, easily recognized by the shiny broad head
(CI 1.12), short eyes (REL 0.46), flattened
mesosoma, blocky petiole, and abundant pilosity
(Fig. 3). For further description see Kempf
(1961:402).
Distribution and biology. This is a widely
distributed but generally uncommon species, found
from Mexico to Argentina and Brazil. P. kuenckeli
appears to have a preference for nesting in large
dead branches, in somewhat open or seasonally dry
forest. Its association with ant acacias is sporadic at
best and based upon two records from Costa Rica:
Emery (1891 : 168) reported a single specimen col-
lected by Alfaro from a swollen-thorn acacia, and
Menozzi (1927b) recorded a collection by H.
Schmidt from Acacia "spadicigera" (probably a
misidentification of A. collinsii) near San Jose.
Pseudomyrmex nigropilosus (Emery 1 890)
(Fig. 7)
PseudomyrmanigropilosaEmery 1890:62. Syntype
workers, Liberia, Costa Rica (A. Alfaro) (MCSN,
MHNG) [Examined].
Pseudomyrmex nigropilosus (Emery); Kempf
1958:453.
Worker diagnosis. With the traits of the P.
gracilis group (see couplet 6 of key) and the follow-
ing more specific features. Head longer than broad
(CI 0.84-0.90); anterior margin of median clypeal
lobe convex, conspicuously protruding; dorsolat-
eral margination of pronotum usually blunt;
mesonotum more steeply inclined than basal face
of propodeum; petiole relatively robust (PLI 0.69-
0.77) with a short anterior peduncle (Fig. 7, 53);
head and mesosoma densely punctulate to
coriarious-imbricate, and subopaque; standing pi-
losity conspicuous on most of the body including
the outer faces of the tibiae, consisting largely of
black hairs, those on the petiole and propodeum
long (> 0.20 mm) and curved. Color varying from
concolorous orange-brown to bicolored orange and
black to (western Mexico) predominantly black
with orange mottling on the head, mesosoma, and
appendages.
Taxonomic comments. Among the
Pseudomyrmex species recorded from swollen-thorn
acacias, P. nigropilosus is easily identified by its
elongate eyes and head (REL 0.55-0.59, CI 0.84-
0.90), short petiole (PLI 0.69-0.77), and conspicu-
ous black pilosity (Fig. 7). Kempf (1958) provides
further descriptive details.
Distribution and biology. P. nigropilosus is
found from Nayarit, western Mexico to Guanacaste
Province, Costa Rica, and is restricted to nesting in
swollen-thorn acacias (including Acacia collinsii,
A. cornigera and A. hindsii). It is a member of the
P. gracilis group and therefore not closely related
to the principal group of acacia-ants (P.ferrugineus
group) . Janzen ( 1 975) points out that P. nigropilosus
is essentially a parasite of the Pseudomyrmexl Aca-
cia mutualism. It occupies abandoned or otherwise
uninhabited plants and reaps the benefits of this
association without protecting the acacia from her-
bivores or competing plants. Additional informa-
tion about the ecology of this species is given in
Janzen (1975).
Pseudomyrmex opaciceps Ward, sp. nov.
(Fig. 5)
Holotype worker. GUATEMALA Retalhuleu:
Puente Samala, 3.8 mi. NE San Felipe, 24.vii. 1966,
D. H. Janzen W006724966 (LACM). HW 1.43, HL
1.42, EL 0.85, PL 0.89, PH 0.39.
Paratypes, Series of 11 workers with same
data as holotype; large series of ca. 60 workers and
10 males with the same locality and collector as
holotype but the following dates and collection
numbers: 18.vii.1966 M002718966 (possibly mis-
labelled - see below), 18.vii.1966 W002718966,
18.vii.1966 W004718966, 18.vii.1966
W0057 18966 (possibly mis-labelled - see below),
23.vii.1966 W002723966, 24.vii.1966
W001724966, 24.vii.1966 W003724966 (BMNH,
LACM, MCZC, MZSP, PSWC, UCDC, U.SNM).
Additional non-type material. Series of work-
ers, queens, and males from six additional locali-
ties. MEXICO Chiapas: 94.5 mi. SE Tonola (D. H.
Janzen). GUATEMALA Retalhuleu: 2 mi.N Puente
Samala, 3.8 mi. NE San Felipe (D. H. Janzen); 3 mi.
N Puente Samala, 3.8 mi. NE San Felipe (D. H.
Janzen); 5 mi. W Retalhuleu, Hwy. CA-2 at Rio Nil
160
JOURNAL OF HYMENOPTERA RESEARCH
(D. H. Janzen); Guatemala: Ciudad de Guatemala
(D. H. Janzen). EL SALVADOR La Libertad:
Quezaltepeque (M. Irwin & D. Cavagnaro) (LACM,
MCZC, PSWC).
Worker measurements (n=14). HL 1.30-1.42,
HW 1.33-1.43, MFC 0.040-0.058, CI 0.99-1.04,
REL 0.57-0.61, REL2 0.56-0.61, OOI 0.14-0.68,
VI 0.65-0.71, FCI 0.029-0.042, SI 0.46-0.50, SI2
0.77-0.88,FI0.36-0.39,PDIL12-1.37,MPI 0.059-
0.076, NI 0.65-0.70, PLI 0.42-0.47, PWI 0.38-0.43,
PPWI 0.92-1. 16.
Worker diagnosis. With the traits of the P.
gracilis group (see couplet 6 of key) and the follow-
ing more specific features. Head about as broad as
long; anterior margin of median clypeallobe straight
to weakly convex; pronotum with blunt dorsolat-
eral margination ; mesonotum more steeply inclined
than basal face of propodeum; petiole long and
slender (see PLI and PWI values) with a distinct
anterior peduncle (Fig. 6); head densely punctulate-
coriarious and matte; standing pilosity abundant,
pale silvery-white, not black. Color: head and
mesosoma dark brown to black, mandibles and
appendages lighter brown; petiole, postpetiole and
gaster a contrasting pale luteous brown or orange-
brown. Portions of the fronto-clypeal complex,
malar area, and mandibles may also be luteous
brown.
Taxonomic comments. This species is distin-
guished from the closely related and sympatric P.
gracilis by a modest but consistent difference in
head sculpture. In workers and queens of P.
opaciceps the punctulate-coriarious sculpture and
associated dense pubescence obscure the sheen of
the head, producing a matte appearance under soft
light, while in P. gracilis the head remains at least
weakly shining. In addition the workers and queens
of P. opaciceps average smaller in size than those
of P. gracilis and they have a more slender petiole
(PLI < 0.48; see Figs. 5, 6, 53). Finally, P. opaciceps
has a distinctive and largely invariant color pattern:
the pale yellow or orange-brown petiole, postpetiole
and gaster contrast with the much darker head and
mesosoma. This is not observed in Central Ameri-
can P. gracilis, although a similar color pattern
occurs in some Colombian populations of P. gracilis,
and it also seen in some individuals of the more
distantly related South American species P. venustus
(F. Smith).
Among the P. opaciceps paratypes in LACM,
the pinned specimens with Janzen collection num-
bers M0027 1 8966 and W0057 1 8966 appear to have
been mis-labelled. In the Janzen alcohol collection
samples M0027 18966 and W0057 18966 contain
colony series of two quite different species (in the
P.ferrugineus andP. pallidus groups, respectively);
but there are two other alcohol samples from the
same date and locality (W0027 18966 and
W0047 18966) which are of P. opaciceps. I con-
clude that a frame-shift occurred in the process of
labelling the pinned series of specimens, producing
the labelling error (this has happened to a substan-
tial number of P. ferrugineus group collections -
see "Materials and Methods" section). The remain-
ing paratype (and non-type) material of P. opaciceps
appears to be correctly labelled.
Biology. P. opaciceps is evidently a generalist
twig-nesting Pseudomyrmex, but Janzen also col-
lected it from an Acacia cornigera tree overgrown
by vines and unoccupied by the P. ferrugineus
group (5 mi. W Retalhuleu, Guatemala, collection
numbers M010714966-A and M010716966-D).
Pseudomyrmex reconditus Ward, sp. nov.
(Fig. 8)
Holotype worfcer NICARAGUA, Madriz: 2.0
mi. S Honduran border,Hwy 1, 840m, 29.vii.1967,
mi. 8207.2, D. H. Janzen, ex Acacia collinsii
(LACM).
Paratypes. One worker, one dealate queen,
same data as holotype (LACM).
Holotype andparatype worker measurements.
HL 1.54, 1.44, HW 1.54, 1.47, MFC 0.071, 0.056,
EL 0.93, 0.86, PL 0.88, 0.78, PH 0.57, 0.47, CI
1.00, 1.02, OI 0.52, 0.52, REL 0.61, 0.59, REL2
0.61, 0.58, OOI -0.01, -0.01, VI 0.73, 0.71, FCI
0.046, 0.038, SI 0.47, 0.47, FI 0.44, 0.39, PDI 1.21,
1.12, MPI 0.067, 0.061, NI 0.62, 0.64, PLI 0.64,
0.60, PWI 0.57, 0.53, PPWI 1.40, 1.25.
Paratype queen measurements. HL 1 .79, HW
1.66, MFC 0.065, EL 1.02, PL 1.21, PH 0.75, CI
0.92, OI 0.5 1, REL 0.57, REL2 0.62, OOI 0.22, VI
0.79,FCI 0.039, SI 0.45, FI 0.46, NI 0.61, PLI 0.62,
PWI 0.61, PPWI 1.53.
Worker diagnosis. With the traits of the P.
VOLUME 2, NUMBER 1 , 1993
161
gracilis group (see couplet 6 of key) and the follow-
ing more specific features. Head as broad as long;
anterior margin of median clypeal lobe slightly
convex, rounded laterally; pronotum with blunt
dorsolateral margination; mesonotum more steeply
inclined than basal face of propodeum; petiole of
moderate length, high (PLI 0.60-0.64), with a dis-
tinct anterior peduncle but without a well devel-
oped anteroventral tooth (Figs. 8, 53), and lacking
sharp dorsolateral margination; postpetiole notably
broader than long. Mandibles weakly striolate,
sublucid, becoming shagreened basally; head and
mesosoma densely but finely punctulate-coriarious
to coriarious-imbricate, subopaque; petiole,
postpetiole, and gaster with fine piligerous punc-
tures, obscured from view by the associated pubes-
cence. Standing pilosity only moderately dense but
with some apparent loss due to abrasion of the type
specimens; hairs mostly black, not silvery-white,
present on the head, mesosoma dorsum, petiole,
and postpetiole; at least some moderately long
(0.23-0.27 mm) hairs on the propodeum and peti-
ole; one or two short hairs present on the outer faces
of the meso- and meta-tibiae, the others possibly
worn off; fine appressed golden pubescence present
on most of the body. Head and mesosoma black,
gaster dark brown, petiole and postpetiole orange;
appendages brown, with orange flecking on the
legs.
Taxonomic comments. This species is known
only from the types. It is readily distinguished from
all other acacia-associated species in the P. gracilis
group by the combination of broad head (see CI
values), robust petiole (PLI 0.60-0.64), and black
pilosity. P. reconditus is similar to an undescribed
Pseudomyrmex species collected from Tachigali in
northern Peru (P. sp. PSW-35) but the latter has a
shorter petiole, more extensive silvery-white pilos-
ity and pubescence, and is all black in color.
Biology. The type collection from Acacia
collinsii is the only record. A single worker of P.
nigropilosus occurred in the same alcohol vial as
the workers and queen of P. reconditus. It remains
to be confirmed that P. reconditus is confined to
nesting in swollen-thorn acacias.
Pseudomyrmex simulans Kempf 1958:459. Holo-
type worker, Tumba Muerta Road, Panama (W.
M. Wheeler) (MCZC) [Examined].
Worker diagnosis. With the traits of the P.
gracilis group (see couplet 6 of key) and the follow-
ing more specific features. Head longer than broad
(CI 0.86-0.90); anterior margin of median clypeal
lobe straight to broadly convex, rounded laterally;
pronotum with sharp dorsolateral margination;
mesonotum more steeply inclined than basal face
of propodeum; petiole relatively short and high
(PLI 0.61-0.66), with a distinct anterior peduncle
(Figs. 9, 53), and with moderate dorsolateral mar-
gination; head and mesosoma finely punctulate-
coriarious to coriarious-imbricate, subopaque;
standing pilosity rather short, pale and inconspicu-
ous, present on the mesosoma dorsum and (usually)
outer surfaces of the tibiae, but sometimes lacking
or worn off on the latter; fine appressed pubescence
on most of body; dark brown-black in color, distal
portions of appendages lighter; mandibles luteous.
Taxonomic comments. This curious species
bears a superficial resemblance to the obligate
acacia-ants (P. ferrugineus group), although its
affinities to other/ 3 , gracilis group species are clear
from eye size, pilosity, palp formula, mesosomal
structure, and male genitalia. P. simulans can be
recognized by the combination of elongate eyes
(REL 0.52-0.55), short petiole (PLI 0.61-0.66),
short inconspicuous pilosity, and black color.
Distribution and biology. P. simulans is known
only from a few collections, all from swollen-thorn
acacias (A. collinsii), in Panama (Canal Zone and
the provinces of Veraguas, Los Santos and Panama).
Nothing has been published about its nesting biol-
ogy or behavior, but Janzen's field notes indicate
that the workers are more timid than those of the P.
ferrugineus group. One might surmise that its hab-
its are similar to those of P. nigropilosus, although
the two species do not appear to be one another's
closest relatives (Ward 1991).
Pseudomyrmex subtilissimus (Emery 1890)
Pseudomyrmex simulans Kempf 1958
(Fig. 9)
Pseudomyrma subtilissima Emery 1890:65. Lecto-
type worker, Alajuela, Costa Rica (Alfaro)
162
JOURNAL OF HYMENOPTERA RESEARCH
(MCSN) [Examined].
Pseudomyrmex subtilissimus (Emery 1890);Kempf
1972:224.
Worker diagnosis. A member of the P.
subtilissimus group, and immediately distinguish-
able from all other acacia-associated Pseudomyrmex
by its small size (HW < 0.60), elongate head (CI <
0.66), apedunculate petiole, and scarcity of stand-
ing pilosity. See Ward (1989:432) for further dis-
cussion of this species.
Distribution and biology. P. subtilissimus has
been collected only in Nicaragua and Costa Rica.
What little is known about its biology suggests that
it is a timid, non-protective species living in the
thorns of Acacia plants occupied by (declining?)
colonies of P. flavicornis.
PHYLOGENY AND BIOGEOGRAPHY OF THE
OBLIGATE ACACIA- ANTS
The 47-character data set used for cladistic analy-
sis of the P. ferrugineus group is given in Table 2.
Implicit enumeration by Hennig86, using the ie*
command, yielded a single most parsimonious tree
of length 73, consistency index 0.86 (0.84 exclud-
ing autapomorphies of ingroup species) (Fig. 73).
This tree has an unresolved trifurcation involving
five Pseudomyrmex species: ferrugineus, janzeni,
and (flavicornis + (mixtecus + veneficus)). These
five species together constitute what may be termed
the P. ferrugineus complex. It is allied to the pair of
sister species, P. spinicola and P. satanicus. The
sister group of these seven species is the isolated
and autapomorphous P. peperi. Finally, P.
nigrocinctus and P. particeps make up a basal pair
of species with relatively unspecialized morphol-
ogy.
Separate analyses of worker-, queen-, and male-
based data sets produced trees in substantial agree-
ment with these findings and largely congruent
with one another (Figs. 74-76). This indicates that
some confidence can be attached to the main fea-
tures of the cladogram, and that homoplasy in
worker and queen morphology possibly due to
parallel selection pressures during diffuse coevolu-
tion of the ant/acacia interaction (see below) has
not been so rampant as to obscure all evidence of
relationship, since both castes point to a cladistic
pattern similar to that derived from male morphol-
ogy (primarily male genital characters). Disagree-
ment revolves around the position of taxa within the
P. ferrugineus complex. Worker morphology sug-
gests that P. mixtecus is more closely related to P.
flavicornis than to P. veneficus. The male character
set supports a (P. mixtecus + P. veneficus) pairing
and is uninformative about other relationships within
the P. ferrugineus complex. The queen-based tree is
identical in topology to that based on all characters,
i.e. it supports (P. flavicornis + (P. mixtecus + P.
veneficus)) but does not resolve relationships among
P. ferrugineus, P. janzeni, and the foregoing trio.
The inferred phylogeny of the P. ferrugineus
group (Fig. 73) suggests that speciation has oc-
curred primarily as a consequence of geographical
isolation. Of the three pairs of sister species, two (P.
nigrocinctus + P. particeps, P. mixtecus + P.
veneficus) are composed of allopatric species (Figs.
69, 72), while the ranges of the third pair (P.
spinicola and P. satanicus) are more or less con-
tiguous (Fig. 68). The trio of species comprising (P.
flavicornis + (P. mixtecus + P. veneficus)) also have
entirely non-overlapping distributions, and they
point to the importance of geographical barriers in
southwestern Mexico to speciation in this complex
(Fig. 69). This is also indicated by the distributions
of P. ferrugineus and P. janzeni, the latter an
allopatric isolate in western Mexico (Fig. 70), al-
though it should be noted that the cladistic analysis
did not confirm a sister group relationship between
these two phenetically similar species. At higher
levels in the cladogram there is some geographical
overlap between taxa, but dispersal has not been so
extensive as to obliterate all evidence of vicariance.
Within the P. ferrugineus complex, for example, P.
flavicornis and relatives are largely confined to the
Pacific slopes of Mesoamerica in contrast to the
more eastern distribution of P. ferrugineus (Figs.
69-70). The P. ferrugineus complex itself is centred
in northern Central America, with only one species
(P. flavicornis) occurring south of Honduras, as far
as Costa Rica in this case, while its sister group (P.
spinicola and P. satanicus) occurs primarily south
of Honduras and extends all the way to northern
Colombia (Fig. 68). This suggests an historical
barrier somewhere in the region of present day
VOLUME 2, NUMBER 1, 1993
163
Honduras or Nicaragua which split these two clades.
The most basal divisions within the P. ferrugineus
group involve much more extensive geographical
overlap, making any historical inferences difficult.
The distributions of the species P. peperi and P.
nigrocinctus are consistent with an origin and early
diversification of the P. ferrugineus group in either
northern or central Mesoamerica. The timeframe
for this is unknown but presumably occurred prior
to the formation of the Panamanian land bridge (i.e.
before early Pliocene or late Miocene). Early diver-
sification in the group may have been encouraged
by the presence of an island archipelago in the
region (Donnelly 1992).
Finally, we come to the question of whether the
phylogenies of the acacia-ants and their host aca-
cias are congruent. A phylogeny of the swollen-
thorn acacias is not available but Janzen's (1974)
revision contains some relevant information. Janzen
(1974) concluded that the Central American swol-
len-thorn acacias are polyphyletic, i.e. that
myrmecophy tism arose more than once or that non-
myrmecophytic acacia species independently ac-
quired myrmecophytic traits through hybridiza-
tion. He also noted (Janzen 1966) that individual
species of acacia can be associated with more than
one Pseudomyrmex species and vice versa. None of
this leads one to expect a pattern of co-speciation,
and mapping known host associations on the
Pseudomyrmex cladogram (Fig. 73) confirms the
opportunistic nature of the interaction. It seems that
most species in the Pseudomyrmex ferrugineus
group occupy any swollen-thorn acacia species
available to them. On the other hand, the possibility
of locally non-random associations between ants
and available plants, perhaps mediated by compe-
tition, deserves investigation.
Three species of acacia-ants, P. janzeni, P.
particeps and P. satanicus, are confined to a single
acacia species (A. hindsii, A. allenii and A.
melanoceras, respectively), the former (P. janzeni)
almost certainly because of its limited geographical
distribution but the last two because of their appar-
ent specialization on the acacia or the forest habitat
to which it is restricted. Populations of other swol-
len-thorn acacia species occur within the probable
dispersal ranges of alate queens of P. particeps and
P. satanicus but are apparently not colonized. These
two host-specific Pseudomyrmex have the smallest
ranges of any members of the P. ferrugineus group
and are clearly the most endangered.
CONCLUDING REMARKS
Table 2. Data set used for cladistic analysis of the_Pseudomyrmex ferrugineus group. P. fervidus served
as outgroup (see text)."?" signifies polymorphism or ambiguity in expression of the character state.
Characters 12, 13 and 16 were considered unordered.
1
11
21
31
41
fervidus
0000000000
7700000001
7000700000
0000000000
0000070
nigrocinctus
0001000001
1021000010
0011001000
0001110010
1001101
particeps
0001000001
1021000011
0010001100
0001110010
1001101
peperi
0011001121
2210020011
0011011001
0002100111
1112212
spinicola
1100101111
010010001?
1110701110
0112100011
1212221
satanicus
1110111111
0100100011
1210201110
0112100011
1212221
ferrugineus
0000001111
0100001011
1110201010
0102101111
1222221
janzeni
0000001111
0100001010
1110201010
0102101111
1222221
flavicornis
0000001111
0100011012
1110201010
0102101111
1222221
mixtecus
0000001111
0100011012
1111111010
0102101121
1222221
veneficus
0000001111
0100001112
1111111010
0102101121
1222221
164
JOURNAL OF HYMENOPTERA RESEARCH
73
outgroup
4 13 1431 36
nil I
all characters
(length 73 ci 0.86)
7 8 9 12 34 40 42 43 44 45 46
I I I I I I I I I I I
3 4 9 11 12 13 16 24 26 30 38 47
i B i i i i i n i i i
3 6 22
11 21 22252529324246
I I I I I I I I I
1 25 152833
I I I I I I
17 37 38 43
I I I I
1620
24252639 || 16 18
=H I I " I
nigrocinctus
particeps al
peperi
satanicus
spinicola
ferrugineus
janzeni
flavicornis
ntixtecus
veneficus
cr ge gl hi
me
al cl cr
ch cl co cr ge gl hi ma sp
hi
cl cr hi
cl hi
cl hi
74
worker characters
(length 29 ci 0.89)
75
queen characters
(length 33 ci 0.75)
76
male characters
(length 28 ci 0.96)
Figs 73-76. Phylogenetic relationships of the obligate acacia-ants, Pseudomyrmex ferrugineus group. 73:
cladogram based on the entire 47-character data set (Table 2), with character state changes indicated and with host
plant associations listed for each species. Solid bars: unique forward changes; hatched bars: homoplasious forward
changes; open bars: reversals. There are alternative, equally parsimonious reconstructions of character state change
for characters 4, 12, 16, 38 and 46. By reference to other Pseudomyrmex species, most changes occurring between
the outgroup (P.fervidus) and the ingroup (i.e. changes in characters 10, 19, 23. ..47) are probably synapomorphies
of the latter, but one character state (27.0) appears to be aderived feature of P.fervidus. The following abbreviations
are used for host plants: al = Acacia allenii, ch = A. chiapensis, cl = Acacia collinsii, co = A. cooki and A. janzenii,
cr = A. cornigera, ge = A. gentlei, gl = A. globulifera, hi = A.hindsii, ma = A. mayana, me = A. melanoceras, sp =
A. sphaerocephala. 74-76: cladograms based on the worker, queen and male character sets, respectively.
VOLUME 2, NUMBER 1 , 1 993
165
This systematic study of Pseudomyrmex ants
associated with swollen-thorn acacias in Central
America demonstrates that the primary group of
obligate acacia-ants (the P. ferrugineus group) is
monophyletic and comprises 1 species. Four addi-
tional unrelated Pseudomyrmex species, from two
other species groups, have become secondary spe-
cialists on the acacias. These latter species appear to
be parasites or commensals but little is known
about their biology (except P. nigropilosus). These
14 specialists are joined by at least six generalist
twig-nesting Pseudomyrmex which occasionally
colonize acacia thorns.
The well known mutualism between ants and
Central American acacias applies with certainty
only to members of the P. ferrugineus group and
their associated plants. Within this group experi-
mental evidence of a mutualism is available only
for the P. ferrugineus x A. cornigera interaction
(Janzen 1966, 1967b), although the biology and
behavior of the other nine species of ants suggest
that they also provide important protection to their
host acacias under most conditions. Cladistic analy-
sis of the P. ferrugineus group, coupled with a
consideration of host plant associations, indicates a
pattern of diffuse coevolution, not one-on-one
cospeciation (see also Janzen 1 966). It seems likely
that the original obligate acacia-ant (the common
ancestor of the P. ferrugineus group) underwent
coevolution with its acacia host, but since then
speciation and diversification of the two groups
have been decoupled the swollen-thorn acacias
are apparently even polyphyletic (Janzen 1974)
and there has been much opportunistic pairing of
ants and plants. Such liberal sharing of partners has
presumably made the association susceptible to
invasion by other Pseudomyrmex and Acacia lin-
eages.
At the same time the key features of the system
absolute dependence of ants in the P. ferrugineus
group on acacia plants, the reliance of at least some
(probably most) of the swollen-thorn acacia spe-
cies on ants for normal growth and reproduction,
and the suite of mutually beneficial traits exhibited
by both partners mark this as one of the more
impressive insect/plant mutualisms known.
ACKNOWLEDGMENTS
I thank the following persons for access to collec-
tions under their care: J. Newlin (ANSP), B. Bolton
(BMNH), M. A. Tenorio (CASC), H. A. Hespenheide
(CHAH), R. Ayala (EBCC), F. Fernandez (FFIC), D.
Quintero Arias (GBFM), A. Solis (INBC), J. T. Longino
(JTLC), R. R. Snelling (LACM; also old loans to D. H.
Janzen from AMNH, CISC, CUIC, GCWC, INHS,
KSUC, MCZC, SEMC, UCDC, UCRC and USNM,
now returned to their original locations), R. Poggi
(MCSN), S. Cover (MCZC), C. Besuchet(MHNG), J. C.
Weulersse (MNHN), C. R. F. Brandao (MZSP), M.
Brancucci (NHMB), M. Fisher (NHMV), D. R. Smith
(USNM), W. P.MacKay (WPMC), F. Koch (ZMHB), O.
Lumholdt (ZMUC), D. R. Abraham (ZMUH) and E.
Diller (ZSMC). Special tribute should be paid to Dan
Janzen whose prodigious efforts in the field yielded a
collection of acacia-ants unprecedented in size and scope,
together with much valuable biological information. I
am particularly grateful to Jack Longino and Roy Snelling
who facilitated my study of the Janzen collection in
LACM. I also received useful acacia-ant material from
Gary Alpert, Diane Davidson, Alain Dejean, Linda
Farley, Doug Gill, Frank Joyce, Alex Mintzer, Dave
Olson, Steve Schoenig, Walter Tschinkel and Dave
Whitacre. This research was supported by NSF grant
BSR-9006393.
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Due to a printer's error all " ^ ", " <, " and " ~ " signs in this paper were replaced by blanks
(although these symbols were present in the page proof), resulting in a significant loss of
information. The affected text follows.
p. 121, column 2, line 30 "PLI2 ^ 0.77"
p. 121, column 2, line 45 "worker PLI ^ 0.71, queen PLI St 0.64"
p. 122, column 1, line 36 "HW < 0.85"
p. 122, column 1, line 37 "HW ^ 0.85"
p. 122, column 1, line 41 "PL/HW k 0.71"
p. 122, column 2, lines 8-9 "CI St 0.94 and/or HW 5: 0.96"
p. 122, column 2, line 15 "SL/HL 5: 0.22"
p. 122, column 2, line 16 "SL/HL 0.21"
p. 130, line 33 "CI 1.12"
p. 130, line 35 "CI 0.80"
p. 132, line 40 "SL/HL ^ 0.21"
p. 132, line 42 "SL/HL ^ 0.22"
p. 133, lines 4-5 "CI 5: 0.94 and/or HW Ss 0.96"
p. 133, column 1, line 8 "MD8/MD9 0.70"
p. 133, column 1, line 11 "MD4/MD5 0.74"
p. 135, column 2, line 4 "worker REL ^ 0.50, queen REL ^ 0.48"
p. 135, column 2, lines 5-6 "worker PLI 0.71, queen PLI ^ 0.63"
p. 135, column 2, lines 29-30 "queen PLI 0.65, queen PL/HL 0.49"
p. 145, column 1, lines 26-27 "REL 0.45, REL2 < 0.56, EL/LHT ^ 0.61"
p. 145, column 1, line 30 "FCI 0.055"
p. 145, column 2, lines 7-8 "worker PWI3 ^ 0.50, worker PPWI s 1.30"
p. 146, column 2, line 10 "CI 0.61"
p. 146, column 2, line 12 "LHT/HW 1.12"
p. 152, column 2, lines 14-15 "(^ 0.10 mm)"
p. 155, column 1, line 20 "REL 0.66"
p. 157, column 1, lines 20-21 "PLI 0.55"
p. 157, column 2, line 12 "MD8/MD9 0.70"
p. 157, column 2, line 17 "MD4/MD5 0.65"
p. 158, column 1, lines 7-8 "PWI3 0.60"
p. 158, column 1, line 41 "REL 0.65"
p. 158, column 1, lines 42-43 "MFC 0.02"
p. 158, column 1, line 44 "CI 0.85"
p. 159, column 1, line 3 "CI 1.12"
Another printing error resulted in the loss of data in column 31 of Table 2 (p. 163):
Pseudomyrmex nigroclnctus and P. particeps should be coded "1", not "0", for character 31.
Other corrections:
p. 121, column 1, line 41
p. 131, line 34
For "public domain software" read "Shareware software"
For "Figs. 10, 34" read "Figs. 11, 34"
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