Revisionary studies on the enigmatic Neotropical ant genus Stegomyrmex Emery, 1912 (Hymenoptera: Formicidae: Myrmicinae), with the description of two new species

2008·13.1 MB·English

HYM. RES.
J.
Vol. 17(1), 2008, pp. 64-82
Revisionary Studies on the Enigmatic Neotropical Ant Genus
Stegomyrmex Emery, 1912 (Hymenoptera: Formicidae: Myrmicinae),
With the Description of Two New Species
RoDRiGO M. Feitosa, Carlos R. F. Brandao and Jorge L. M. Diniz
(RMF, CRFB) Museu de Zoologia da Universidade de Sao Paulo, Av. Nazare 481, Sao Paulo, SP,
04263-000, Brazil; RMF email: [email protected]; CRFB email: [email protected]
(JLMD) Campus Jatai, Unidade Jatoba, Universidade Federal de Goias, BR 364, km 192, Jatai, GO,
75800-000, Brazil; email: [email protected]
—
Abstract. The recent increase in leaf litter ants sampling effort in Neotropical wet forests has
re\'ealed new and interesting records of the highly specialized myrmicine ant genus Stegomyrmex
Emery,previouslyconsideredasextremelyrare.Wepresentamodifieddiagnosisforthegenusand
describe Stegomyrmex bensoni n. sp. and S. olindae n. sp., based on, respectively, workers, males,
and gyne (central-north Brazil) and ona singleworker (northernBrazil). Stegomyrmex vizottoiDiniz
(southeastern Brazil) is redescribed and compared with S. olindae n. sp.; these species present
significant differences in size, sculpturation, and sting apparatus morphology. The males of S.
vizottoiaredescribed forthefirsttime. Akeyforworkers andqueens andadistributionmap forthe
five know Stegomyrmex species are provided.
Stegomyrmex is the sole representative of species, S. manni, from Barro Colorado
the pecuhar and exclusively Neotropical Island, Panama, and agreedwithWheeler's
myrmicine tribe Stegomyrmecini (Bolton placement of the genus in an individual
2003). These ants have been considered tribe.
extremely rare by many authors, perhaps Bernard (1951) and Lenko (1965) com-
due to their cryptobiotic habits enhanced mented on the morphological resemblance
by peculiar soil-binding pilosity (Holldo- of Stegomyrmex to some Attini. However,
bler and Wilson 1986), and by the foraging Brown (1949), Brown and Kempf (1960),
technique they employ (Diniz and Brandao and Holldobler and Wilson (1986) consid-
1993). How^ever, recent collections employ- ered stegomyrmecine ants more closely
ing large-scale sampling (e.g. Agosti et al. related to Basicerotini than to Attini or
2000) have revealed that they are relatively Dacetini, mainly by the presence of deep
common inhabitants of the dense leaf litter antennal scrobes and the soil-binding
of Neotropical forests. pilosity. Dlussky and Fedoseeva (1988)
Emery (1912) described Stegomyrmex considered Stegomyrmex as incertae sedis
with a single species, S. connectens, based in Myrmicinae, without further discus-
on a gyne and a male from Peru and sion. However, in the last proposals of
Bolivia respectively. Emery included Ste- Bolton (1994, 2003, 2006 et al), Stegomyr-
gomyrmex in the Dacetini based on gyne mex is placed in its own tribe within the
characters. Wheeler (1922) estabhshed a Myrmicinae. Bolton (2003) commented
new tribe, Stegomyrmicini (sic), with Ste- that the structure of the promesonotum
gomyrmex as its only member. He separat- may suggest a relationship betw^een Ste-
ed it from the Dacetini mainlyby the shape gomyrmecini and Pheidolini, but that
of mandibles and wing venation. Smith there is no undisputed evidence for this
(1946) described the second Stegomyrmex yet.
Volume 17, Number 1, 2008 65
Lenko (1965) found a worker of S. METHODS
vizottoi (identified by him as S. manni) in This study was based on the available
the gizzard of a Conopophaga lineata Wied specimens in the collection of the Museu
(Aves, Conopophagidae). Holldobler &
de Zoologia da Universidade de Sao Paulo,
Wilson (1986) commented on the pre- Sao Paulo, Brazil, which is believed to hold
sumed role of the soil-binding hairs of mostofthe known Stegomyrmex specimens.
basicerotine and stegomyrmecine ants in
Depository collections are referred to by
enhancing their camouflage to predators.
the following acronyms:
Diniz (1990) was the first to revise the BMNH - The Natural History Museum,
taxonomy of Stegomyrmecini, describing
London, UK.
the third species of the genus, Stegomyrmex CASC -California Academy of Sciences,
vizottoi, based on workers and a gyne from
San Francisco, California, USA.
Brazil and Paraguay. In the same work, CPDC - Centro de Pesquisas do Cacau,
Diniz commented on the relati\"ely slow
Itabuna, Bahia, Brazil.
movements of stegomyrmecine ants.
JLMD - Laboratorio de Zoologia, Cam-
Diniz and Brandao (1993) were the first to
pus Jatai, Universidade Federal de Goias,
describe the nesting habits of Stegomywiex,
Brazil.
basedonobser\^ationsoncoloniesofS.vizottoi LACM - Los Angeles County Museum
from Mirassol, state of Sao Paulo, Brazil,
of Natural History, Los Angeles, Califor-
describing nest architecture, population dis-
tribution among nest chambers, different niaM,CUSSAN. - Museo Civico di Storia Natur-
worker behaviors at each part of the nest,
andtheforaginghabitsoftheworkers,which ale ''Giacomo Doria", Genoa, Italy.
MPEG -Museu Paraense Emilio Goeldi,
exploit the en\^ironment surrounding their
nests singly, searchingformyriapod eggs. Belem, Para, Brazil.
MZSP - Museu de Zoologia da Uni-
Recent sur^^eys of leaf litter ants in the
Brazilian Atlantic forest and in sparse versidade de Sao Paulo, Sao Paulo, Brazil.
localities of central and northern Brazil USNM - National Museum of Natural
revealed several Stegomyrmex specimens, History - Smithsonian Institution, Wash-
including a remarkable new species de- ington, DC, USA.
scribed here, and extending considerably The terms for external morphology and
the known distribution range of S. vizottoi. surface sculpturing follow, respectively,
Our analysis of S. vizottoi along its distri- Bolton (1994, 2000) and Harris (1979). The
bution shows, however, that, as presently terms for wing venation follow Brown and
accepted, it includes two distinct species, Nutting (1950). The reproductive females
recognizable by the surface sculpture, by are here called ''gynes", as suggested by
morphometry, and by differences in the De Andrade and Baroni Urbani (1999).
sting apparatus, as we fully describe and Measurements were obtained with a
comment on below. micrometric reticule and using the scale
In this paper we offer taxonomic notes of a scanning electron microscope (SEM).
on the peculiar ant genus Stegomyrmex, All measurements are given in mm, and
based on the study of the specimens the abbreviations used are:
deposited in the Museu de Zoologia da HW: head width; the maximum width of
Universidade de Sao Paulo ant collection, the head capsule, measured in full face
literature information, and enriched by view, at a median transverse line that
unpublished observations. We also de- touches the superior margins of the com-
scribe two new species and comment on pound eyes.
new records and information regarding HL: head length; the maximum measur-
these seldom collected ants. able length of head capsule excluding the
66 Journalof Hymenoptera Research
mandible, measured in full face view, in a in xylene, and then mounted in Canada
straight line from the midpoint of the balsam for observation and illustration
anterior clypeal margin to the midpoint of under optical microscope. The terms for
the \'ertexal margin. sting apparatus morphology follow Kugler
SL: antennal scape length; the chord (1978).
length of the antennal scape, excluding Coordinates of localities were obtained
the basal condyle and its peduncle. from the information on the specimens
WL: mesosoma length (Weber's length); labels and after consulting the ENCARTA
the diagonal length ofmesosoma inprofile, World Atlas® (Microsoft); they were plot-
from the midpoint of the anterior pronotal ted on the distribution map generated by
decli\ity to the posterior basal angle of the the software ArcView 3.2 GIS®.
metapleuron. When citing label data, we present
PL: petiole length; the longitudinal axis additional information between brackets,
of petiole in lateral view. explanationofcodes on the labels, eventual
PPL: postpetiole length; the longitudinal corrections to the misprints, and reference
axis of postpetiole in lateral view. to the notebooks from which we took
GL: gaster length; the maximum length information regarding the localities and/
of gaster in lateral view, excluding sting. or the biology of the species.
TL: total length; the summed length of
HL (plus the closed mandibles), WL, PL, RESULTS
PPL, and GL.
CI: cephalic index. HW x 100/HL. Stegomyrmex Emery, 1912
SI: scape index. SL x 100/HW. Stegomyrmex Emery, 1912: 99. Gyne. Type
The SEM images of Stegomyrmex speci- species: Stegomyrmex connectens, by mono-
mens were obtained from a single speci- typy. Emery, 1912: 101 (placement in Dace-
men of each species. The specimens were tini); Emery, 1914: 42 (placement in Dace-
previously cleaned in acetone, critical- ttni); Forel, 1917: 246 (placement in Dacetini);
point dried in a Balzer (Bal-Tec® CPD Emery, 1924: 314 (placement in Dacetini,
030), and sputtered over with gold (Bal- diagnosis, catalogue); Wheeler, 1922: 668
Tec® SCD 050). After that, the specimens (establishment of Stegomyrmecini [as Stego-
were mounted on the tip of metallic myrmicinij); Donisthorpe, 1943: 727 (place-
triangles using silver glue and then affixed ment in Dacetini, list of type specimens);
Smith, 1946: 286 (revision); Brown and
to stubs for the electron microscopy. The
Kempf, 1960: 162 (systematic notes); Lenko,
images were obtained under several mag-
1965: 201 (distribution and biology); Kempf,
nifications (40 to 300x), according to the 1972: 242 (catalogue); Wheeler and Wheeler,
size of the specimen and/or structure 1985: 258 (tribal classification); Holldobler
observed. Finally, the images were edited and Wilson, 1986: 16 (pilosity); Dlussky &
(Adobe PhotoShop 7.0®) to enhance some Fedoseeva, 1988: 81 {incertae sedis in Myrmi-
brightness and contrast details. cinae); Diniz, 1990: 277 (revision, species
We studied also the sting apparatus of key); Holldobler and Wilson, 1990: 15 (tribal
the species from which we had enough classification); Brandao, 1991: 379 (cata-
individuals. The sting was obtained by logue); Diniz and Brandao, 1993: 301 (biol-
rehydrating ants in 70% ethanol, extracting ogy); Bolton, 1994: 106 (catalogue); Bolton,
1995a: 1052 (census); Bolton, 1995b: 392
the terminal segments from the gaster,
clearing them in 55-60 C lactophenol for (catalogue); Serna, 2002: 217 (first record
for Colombia); Bolton, 2003: 255 (diagnosis,
five minutes (or longer if necessary), synoptic classification); Fernandez and Os-
rinsing twice in 70% ethanol, and twice in pina, 2003: 49 (census); Fernandez, 2003: 325
95% ethanol. After the clearing process, the (genera list for Neotropics); Bolton et al.,
sting apparatus was dismembered, soaked 2006 (catalogue).
Volume 17, Number 1, 2008 67
mm
Worker. Monomorphic. 5 to 6.5 in from the integument sculpture; placed on
length. Reddish brown to black. Integu- the sides of head immediately beneath the
ment thick, shining and in general densely antennal scrobe, but visible when head is
areolate, except for S. bensoni. Pilosity in full face view.
conspicuous and bizarre; hairs varying Mesosoma, in dorsal view, slender,
from short, subdecumbent and filiform to widest at the level of the anterior area of
long, suberect, and variably branched; pronotum. Promesonotum evenly rounded
mandibles sparsely covered by long fili- inprofile, dome-like; anterosuperior corner
form hairs; anterior margin of clypeus of anepisternum set much lower than the
bearing one or two pairs of very long adjacent surface, forming a deep fovea;
setae, reaching half the length of mandi- promesonotal suture almost obsolete in
bles, but without an isolated median seta; some individuals. Mesonotum elongate
appendages covered by short decumbent with posterior portion sloping down; me-
hairs and by a fine and dense appressed tapropodeal impression relatively broad
pubescence; inferior corners of pronotum and usually shallow, except for S. bensoni.
with a dense row of plumose hairs. Propodeum, in side view, variably convex
Head subtrapezoidal with vertexal mar- dorsally, and with the declivity sinuous;
gin slightly depressed to slightly convex; propodeal spiracles low on side and raised
occipital corners angulate; broader pos- in prominent, subcylindrical protuberanc-
terad. Palpal formula 2:2. Labrum bilobed. es; propodeal spines short and more or less
Mandible triangular, long, strongly curved acute; propodeal lobes large and usually
downapicallyandwiththeblades crossing projected over the petiolar peduncle. Legs
apically when m.andibles are closed; mas- relatively long; femora and tibiae moder-
ticatoryborder multidenticulate (total den- ately incrassated; tarsal claws simple;
tal count 12-15), with the apical tooth metatibial spurs absent.
longer than the preceding ones. Median Petiolelongandpedunculate,withabout
portionofclypeusnarrow, flatandvertical, twice the length of the postpetiole; petiolar
not bicarinate, quite narrowly inserted node variably convex in profile; ventral
between the frontal lobes. Frontal lobes carina present and bearing 0-2 blunt
enormously expanded anterolaterally and anterior projections. Postpetiole approxi-
projected far out over the lateral portions mately as long as broad, globose, without
of clypeus and mandibles. Each frontal ventral process. Gaster oval, without basal
lobe covering dorsally a very deep anten- shoulder; tergite of abdominal segment IV
nal scrobe; in full face view, spacebetween (first gastral) not broadly overlapping
frontal lobes narrowest near the middle of sternite on gaster ventral surface.
head, revealing the compound eyes; clyp- Sting apparatus. Spiracular plate with
eus and basal portion of mandible entirely spiracle placed ventrally; anal plate with
concealed by the frontal lobes. Frontal area several sensillae; lancet with a pair of
impressed, glabrous and smooth, the ante- functional valves; furcula with indistinct
A
rior suture obsolete. shallow groove, dorsal arms.
almost devoid of any sculpture, present on Gyne. Like conspecific worker, with the
each side of the head dorsum, extending modifications expected for myrmicine
from the frontal area to the occipital corner gynes. Anterior ocellus slightly larger than
of head, the two grooves meeting anterior- posterior ones. Notauli and parapsidial
ly, forminganoticeable V. Antennawith 12 lines usually indistinct from surrounding
segments, with a three-segmented club; sculpture; prescutellum with central area
antenal scape slender, curved basally and indistinct, scutoscutellar sulcus shallowly
broader at apex. Compound eye exceed- impressed, with transversal rugulae vary-
inglysmall, ovalinshape, almostindistinct ing in number and forming distinct cells;
68 Journalof Hymenoptera Research
lateral wing of prescutellum not projecting Mesosoma robust; prescutellum separat-
laterally; scutellum semicircular, with its ed from scutellum by an impression with
posterior half always sloping down and shortlongitudinal rugae. Scutellumnarrow
with posterior border concave; propodeal posterad. Metanotum narrow, with blunt
spines shorter than in conspecific workers. median tumosity. Propodeum dorsal face
Forewing with distinct and strongly flat, steeply sloping posterad, unarmed.
colored stigma; longitudinal veins Sc+R, Legs slender, middle and hind tibiae
SR, M+Cu, and A present. Cells R, Cu and without apical spurs; tarsal claws
IM closed. Hind wingwith Sc+Rextending slender and simple. Wing venation as in
shortlybeyondpointwhere theycormectto the gynes.
M, which extends as a tubular vein up to Petiole clavate, pedunculate, and with a
the wing distal border; Cu cell closed and long, low, rounded node. Postpetiole as
very short; six to eight submedian hamuli. broad as long, attached to the gaster by
Male. Dark brown to black, with ap- almost its full width. Gaster elongate, with
pendages and gaster usually lighter. Integ- first segment occupying most of its length;
ument densely sculptured, opaque or visible apical segments subequal in length.
—
nearly so, except for the postpetiole and Comments. We revise the Stegomyrmex
gaster which are smooth and shining; diagnosis presented by Diniz (1990) in
appendages very finely punctate. Pilosity order to include information on the shape
composed of fine hairs, whitish to golden, of the head and on the structure of the
mostly curved or suberect onbody, sparser alate's mesosoma, besides features present
on metasoma. Apressed pubescence on in S. bensoni n. sp and S. olindae n. sp.
antennae and legs. Apomorphies for Stegomyrmecini defined
Head broadest across compound eyes, by Bolton (2003) hold true for the new
narrowed anteriorly; median portion of species.
vertexal margin usually weakly convex; Despite the recent information regarding
occipital corners rounded; ocelli promi- these seldom collected ants, the phyloge-
nent. Mandible relatively developed and netic position of Stegomyrmex remains truly
subtriangular; masticatory border multi- enigmatic. The affinities with Dacetini and
denticulate, with the apical tooth much Attini, proposed in the past, seem improb-
more developed than the others. Clypeus able by the significant differences in habits
broad. Frontal lobes not so developed as in and morphology. Despite the body sculp-
the conspecific gynes and workers, but turation patterns and the presence of
concealing the antennal insertions, forming specialized pilosity approximating Stego-
a short and shallow antennal scrobe. myrmex and Basicerotini (Holldobler and
Antennae long and slender with 13 seg- Wilson 1986), the possibility of homoplasy
ments; scapes relatively short. can not be presently discarded.
REVISED KEY TO THE STEGOMYRMEX SPECIES (WORKERS AND GYNES)
1. Integument of mesosoma predominantly smooth and shining; body covered mainly
by sparse aggregations of somewhat curved and multibranched hairs; metapropo-
deal groove deeply impressed; petiole without anteroventral spines (state of Para,
Brazil) S. bensoni sp. n.
- Integument of mesosoma predominantly sculptured, areolate; body covered mainly
by sparse and erect clavate setae; metapropodeal groove only moderately
impressed; petiole with at least one anteroventral spine 2
Volume 17, Number 1, 2008 69
2. Petiole with two anteroventral spines; inferior margin of pronotum with a row of
filiform hairs; known only from the gyne (Peru and Bolivia) . . . S. connectens Emery
- Petiole with a single anteroventral spine; inferior margin of pronotum with a row of
plumose hairs 3
3. Promesonotummuchhigherthanpropodeum,inlateralview;propodeal spinesblunt
and directed posteriorly; in dorsal view propodeal spiracles strongly projected
laterally (Costa Rica, Panama and Colombia) S. manni Smith
Promesonotum slightly higher than propodeum, in lateral view; propodeal spines
subtriangular, acute and directed upwards; in dorsal view propodeal spiracles not
strongly projected laterally 4
4. Mesosomalength > 1.59 mm;mesosomapartiallysculptured,withfoveaesparselyset
on the polished integument; metapropodeal impression without a projecting
tubercle;nucalareapredominantlysmooth;indorsalviewbasalfaceofpropodeum
relatively narrow (northern Argentina, Paraguay and southeastern Brazil)
S. vizottoi Diniz
- Mesosoma length < 1.59 mm); mesosoma strongly sculptured, with the integument
completely areolate; metapropodeal impression with a projecting tubercle; nucal
area predominantly sculptured; in dorsal view basal face ofpropodeum relatively
broad (central-north Brazil) S. olindae sp. n.
Stegomyrmex bensoni n. sp. and shining, except for a iew scattered
(Figs 1, 7) punctures at the inferior portion of meso
— and metapleuron; legs smooth and rather
Holotype worker. BRAZIL: Para, Canaa opaque; petiole and postpetiole smooth and
dos Carajas (06°44'49''S, 50°2r05"W) shining w^ith some sparse piligerous punc-
(Gruta NV06) 22-28.ii.2005 (Andrade & tures; dorsum of gaster feebly shining and
Arnoni) [MZSP]. vv^ith sparse and fine punctuation.
Worker description.—YM 1.26; HL 1.09; Pilosity golden and extremely diverse;
ML 0.61; SL0.84;WL 1.77; PL 0.78; PPL 0.45; sparse filiform hairs covering the dorsum
GL 1.70; TL 6.40; CI 115.56; SI 66.35. Color of mandible, external borders of frontal
reddish brow^n. Basal portion of mandible carinae, antenal scapes, legs, dorsum of
finely and densely striate, v^^ith large and mesosoma and metasoma; long, slightly
sparse piligerous punctures, apical portion curved, moderately clavate hairs present
and masticatory border mostly smooth and on dorsum of head and promesonotum;
shining; inner surface of antennal scrobes short, curved, branched hairs present on
w^ith fine, dense, transversal and concentric head occipital corners, dorsal surface of
striation; dorsal surface of head predomi- legs and gaster; posteroventral corners of
nantly smooth and shining, w^ith scattered head, anterior and lateral portions of
punctures near the vertexal border; margin promesonotum, dorsum of metanotum
offrontallobesfinelyareolate-rugose;central and propodeum, ventral and lateral faces
portion of each frontal lobe virtually trans- of v^aist and anterior portion of gaster (in
lucent,sothatispossibletoobservetheinner special the sternite) with aggregations of
surface of the antennal scrobes near the long, multibranched (plumose), curved
insertions ofantennae; antennaeopaqueand hairs, so that the integument is hardly
finelypunctate;lateralandventralsurfaceof visible in these areas.
head deeply areolate; occipital face of head Head vertexal margin convex in the
smooth and shining except for the nucal middle. Compound eyes exceedingly
coUar v^hich is regularly and deeply scrobi- small, w^ith circa three almost indistinct
culate; mesosoma almost entirely smooth facets at the maximum diameter.
70 Journalof Hymenoptera Research
Fig. 1. Stegomynnex bensoni n. sp., worker. A, head in full face view; B, SEM close-up view ofpromesonotal
multibranched hairs; C, habihis.
Promesonotum strongly convex dorsal- petiolar peduncle without anterior projec-
ly; metapropodeal groove deeply im- tions. Postpetiole strongly convex dorsally
pressed; propodeal spines short and sub- and without ventral processes. Gaster oval
triangular, entirely covered by the propo- and robust.
—
deum pilosity; propodeal spiracle wide Gyne. Unknown.
—
open, and moderately projected laterad; Male. Unknown.
—
propodeal lobes subquadrate and weakly Etymology. Species named after the
projected over the petiolar peduncle. prominent Brazilian-American ecologist.
Petiole elongate, slightly arched, with a Woodruff Whitman Benson, well known
prominent rounded node; ventral carina of for the study of ecological interactions in
Volume 17, Number 1, 2008 71
Brazilian ecosystems. He organized for and 1 gyne) [LACM]; Mato Grosso: Sto.
several years a field course on Ecology Antonio de Leverger, Aguas Quentes (High
(graduate program of the Universidade Cerrado) (n. 0184) 26.X.1984 (J.C. Trager) (1
Estadual de Campinas, Sao Paulo), given worker) [MZSP]; Minas Gerais: Timoteo, P.E.
for several years in the Serra dos Carajas, doRioDoce (TM3-8) 07.V.2005 (Esteves,F.A.) (1
worker) [MZSP]; Tocantins: Palmeirante (Mata
Para, where generations of Brazilian grad-
Ciliar/Cerradao) (07-52'25"S, 47=31'48'W) 10-
eunactee,satnuddenwthserheadthteheuinriqfiurestkfnieoldwnexsppeerci-- 1[5M.ZxSiiP.]2;00s1a(mAeldbautqaue(r1qwuoerkaenrd) S[iClAvSa)C](;1 Awroargkuear)-
imen of S. be—nsoni was found. cema (08=59'20"S, 49=40'41'W) 16-30.xi.2005
Comments. The peculiar multibranched (Silva, R.R. and Feitosa, R.M.) (1 worker)
pilosity, allied to the deep metapropodeal [MZSP]; same data (1 worker) [MPEG]; same
groove, and the absence of anteroventral data (1 worker) [USNM]—.
petiolar projections, easily separate this Worker description. Holotype (workers
species from all others in the genus. N= 8); HW 1.09 (1.04-1.22); HL 0.97 (0.92-
The single worker known thus far was 1.07); ML 0.49 (0.46-0.49); SL 0.74 (0.69-
captured by our colleague arachnologist, 0.80); WL 1.43 (1.33-1.53); PL 0.68 (0.61-
Renata Andrade, while searching for cav- 0.70); PPL 0.39 (0.33-0.44); GL 1.36 (1.24-
ernicolous pseudoscorpions in Serra dos 1.50); TL 5.32 (5.01-5.70); CI 113.75 (104.88-
Carajas, southeastern state of Para (Ama- 114.63); SI 66.59 (63.83-67.44). Dark brown
zon region), Brazil. The finding represents to ferruginous, with appendages some-
the first record of a stegomyrmecine ant in what lighter. IMandible finely and densely
the Amazon Region. striate, with large and sparse piligerous
Despite the fact that the only know punctures, except for the masticatory bor-
specimen was collected inside a cave, near der and dorsum of apical portion which
its mouth, there is no undisputed evidence are smooth and shining; inner surface of
that Stegomyrmex bensoniisrestricted tothis antennal scrobes punctate and with fine
habitat. transversal striation; central disc of head
and externalmargin offrontal lobes dense-
Stegomyrmex olindae sp. n. ly areolate-rugose; oblique lateral grooves
(Figs 2, 3, 6, 7) of head, frontal area and posterior portion
—
Holotype worker. BRAZIL: Tocantins, of frontal lobes with smooth areas and
Palmeiras do Tocantins (06°40'12"S, sparse punctuation; anterior portion of
47°31'48"W) (Winkler n.3) 14-19.1.2005 (Sil- frontal lobes shallowly areolate and with
va, R.R. and Silvestre, R.) [MZSP]. irregular longitudinal rugulae; antennae
Stegomyrmex vizottoi Diniz, 1990: 290 (in opaque and finely punctate; lateral, ventral
and occipital surfaces of head deeply
part).
areolate; mesosoma (including the anterior
Pflrafypes.—BRAZIL: Bahia: Ilheus, CEPEC- coxae), petiole, and postpetiole entirely
area Zoolog. (Kjn22 lUieus-Itabuna) x.1986 and deeply areolate; legs opaque and
(J.
Delabie) (1 worker) [MZSP]; Porto Seguro, E.E. weakly sculptured; surface of gaster deep-
Pau Brasil (16°23'33"S, 39°10'99nV) (Winkler ly and densely foveolate.
n.l) 16.vi.2000 (Santos, J.R.M and Soares,J.C) (1 Pilosity cream-colored. Body covered by
worker) [MZSP]; Maranhao: Agailandia, Horto abundant, long, slightly stiffened, moder-
Faz. Pompeia (04=52'30"S, 47=17'40'W) 13- atelyclavate hairs, somewhat shorter inthe
22.ii.2006 (Silva, R.R. and Feitosa, R.M.) (1
external borders of frontal lobes, antenal
worker) [MZSP]; Estreito, Fazenda Itaueiras
(06=31'54"S, 47°72'16'W) 07-13.1.2005 (Silva, scapes, and legs; mandible with long,
R.R. and Silvestre, R.) (2 workers and 1 gyne) sparse filiform setae; short, curved, plu-
[MZSP]; same data (1 worker) [BMNH]; same mose hairs present on the posteroventral
data (1 worker) [CDPC]; same data (1 worker corners of head, inferior and lateral por-
72 Journalof Hymenoptera Research
tions of pronotum, and more rarely on the sensilla sparsely distributed over the plate
lateral surfaces of waist; occipital face of dorsum. Oblong plate with long posterior
head and lateral surface of mesonotum, apodema; subterminal tubercle with
metanotum, and propodeum virtually gla- rounded apex; postincision well devel-
brous. oped. Conostylus one-segmented and
Vertexal border gently convex and with with six chaetae, five subequal in length
a discrete concavity medially. Compound and one extremely long; terminal sector
eyes with circa six facets at maximum short and membranous, with dorsoterm-
diameter. inal and companion chaetae present.
Promesonotum strongly convex dorsal- Triangular plate as long as broad, without
ly, in lateral view; promesonotal suture tubercles or projections. Lancets with
distinct only in the lateral faces of prome- functional valves; sensorial barbies absent;
sonotum; anepisternum set lower than the dorsal and ventral margins converging
adjacent surface; metapropodeal groove towards the apex. Sting shaft weakly
relatively large, moderately impressed sclerotized, probably not perforating; dor-
and with a median triangular projection; sum of valve chamber indistinct in pro-
propodeal spines subtriangular, directed file; internal apophysis absent; basal con-
upwards and with the posterior faces nection gently concave; anterolateral pro-
enlarged medially; propodeal spiracles cesses well developed, as broad as the
relatively wide, and considerably projected furcula lateral arms; campaniform sensilla
posterad; propodeal lobes rounded and absent. Dorsal arm of furcula relatively
moderately projected over the petiolar reduced, indistinct; lateral arms well
peduncle. In dorsal view, the propodeum developed; fulcral articulation connected
is relatively broad, slightly narrower than to the sting basis only by its lateral
the promesonotum. corners.
Petiole elongate, gently arched, with a Gijne.—{N= 2); HW 1.24-1.26; HL 1.04;
relatively long rounded node; ventral ML 0.52-0.53; SL 0.78; WL 1.82; PL 0.80-
carina of peduncle with a well-developed 0.83; PPL 0.46-0.49; CL 1.82-1.84; TL 6.50-
anterior projection. Postpetiole with a long 6.51; CI 118.60-120.93; SI 62.12-62.75. Like
and moderately convex dorsal face, with- conspecific worker, with the modifications
out \^entral projections. Caster oval and expected for myrmicine gynes. Plumose
robust. hairs restricted to the posteroventral corner
Sting apparatus (Fig. 3): Spiracular plate of head and inferior corner of pronotum.
subquadrate, not extending towards the Compound eyes with circa 11 facets at
medial connection; margin of medial maximum diameter; propodeal spines
connection sclerotized; dorsal notch ab- drastically reduced; posterior face of pro-
sent; spiracle relatively wide and set close podeum vertical in side view, reaching the
to the posterior margin of plate; anterior propodeal lobes in a rounded angle. Wings
apodema narrow with the medial region unknown.
—
with a distinct angle; ventral edge vesti- Male. Unknown.
—
gial, marked only by a weak projection. Etymology. This species is named after
Quadrate plate with the dorsal region as Florinda Gonzaga Teixeira, a long-term
broad as the ventral region, except for the and always large-hearted steward of the
apodema; apodema area smaller than the MZSP ant lab, at the occasion of her
plate body; dorsal margin convex; apex of retirement. She prefers to be called "Dona
anterodorsal corner rounded; posterior Olinda", hence the specific name.
—
margin complete. Anal plate with the arc Comments. While examining specimens
rounded and strongly sclerotized; apical of Stegomyrmex vizottoi from the MZSP
margin rounded and weakly definite; anal collection, one of us (RMF) noticed that
Volume 17, Number 1, 2008 73
5j^^
%
'i ->
Fig. 2. Stegomyrmex olindae n. sp., worker (SEM). A, head in full face view; B, close-up view of nucal area;
C, habitus.
there was a morphologically distinct sub- ofBahia (northeastern Brazil) presented the
group of individuals, all collected in the lateral faces ofthe mesosoma more densely
northern range of S. vizottoi distribution. sculpturedandthebasalfaceofpropodeum
Diniz (1990) already mentioned, while relativelyenlargedindorsalviewinrelation
commenting on the original description of to other specimens,buthe considered these
S. vizottoi,thataspecimenfromIlheus, state characteristics as geographical variations