A revision of male ants of the Malagasy region (Hymenoptera: Formicidae): Key to genera of the subfamily Dolichoderinae
Author
Yoshimura, Masashi
Author
Fisher, Brian L.
text
Zootaxa
2011
2794
1
34
journal article
10.5281/zenodo.276993
ffd678ac-fc09-4a69-9cad-46daa901de52
1175-5326
276993
Tapinoma
Foerster 1805
(
Figs 4
,
9
,
14
,
23
,
27
,
29
,
37
,
44
,
47
,
53
,
59, 60
,
65
,
70
,
75
,
80
)
With characters of
Dolichoderinae
. All known males alate. Medial hypostoma present (
Fig. 65
). Mandible triangular, but its basal angle indistinct. Basal margin of mandible partially covered with serrate denticles and with smooth margin on its basal portion (
Fig. 75
). Masticatory margin of mandible wholly covered with serrate denticles. Apical tooth on masticatory margin longer than subapical one. Palpal formula 6,4 or 6,3 (one specimen each of seven species and morphospecies dissected:
Fig. 80
:
Table 3
). Length of third maxillary palpal segment varies from shorter to longer than fourth. Distal margin of labrum deeply concave and bilobed, longest setae located near apices of lobes (
Fig. 70
). Scape excluding basal condyle longer than flagellar segments 1+2 (
Fig. 4
). Pedicel conical. First and second flagellar segments straight. Axillae medially compressed, anterior and posterior margins not parallel. Petiolar node strongly inclined anteriorly, its anterior margin much shorter than posterior margin in lateral view. Node not much expanded laterally in most cases. Petiole narrowly attached to abdominal segment III. Anterior surface of abdominal segment III with indentation that fits posterior surface of petiolar node. Pygostyles present.
Distal portion of abdominal sternum IX bilobed, its distal margin widely or narrowly concave (
Fig. 27
). Apicoventral portion of basimere with projection (
Fig. 29
). Harpago moderate in size, separated from basimere by membranous region or a suture, and narrow in ventral view without ventral face (
Fig. 23
). Basal portion of aedeagus without distinct ventral lobe (
Fig. 44
). Ventral margin of aedeagus with denticles.
Forewing not extremely elongated apical to wing stigma, radial sector reaches costal margin (
Fig. 53
), media
absent
between Rs+M and 2rs-m, and 1m-cu
absent
in most cases. On hindwing, M+Cu present, 1rs-m+M, free sections of radial sector and cubitus, and cu-a present or
absent
(
Figs 59, 60
).
Remarks.
Males of seven species (some of them morphospecies) were examined. Males of
Tapinoma
are distinguished easily from those of the four other
Malagasy
genera by an antennal scape which is longer than flagellomeres 1+2, and basal margin of the mandible partially covered with serrate denticles with a smooth basal portion (
Fig. 75
). In addition to these unique characters, an anteriorly inclined petiolar node is found only in
Tapinoma
and
Technomyrmex
and an apicoventral process of the basimere is found only in
Tapinoma
(
Fig. 29
) and
Aptinoma
(
Fig. 30
).
The following is a summary of the characters in
Table 3
that distinguish between
Tapinoma
and
Technomyrmex
: basal margin of the mandible (character 4), apical portion of the labrum (character 7), relative length of the antennal scape (character 8), a process on the basimere (character 19), shape of the harpago (character 20), media on the forewing (character 23), and M+Cu on the hindwing (character 23). These differences hold up even though
Technomyrmex
is listed as having multiple states for the labrum (characters 7), and
Tapinoma
with a polymorphism for the scape (character 8). The ambiguity in
Technomyrmex
is due to an inability to dissect a
paratype
of
Technomyrmex curiosus
. Though
Tapinoma
is polymorphic in scape length, it never overlaps with the status observed in
Technomyrmex
.
A reduction of wing venation is observed in two species:
T
.
subtile
(
Fig. 60
) and
T
. mg07. The hindwings of both species are much narrower than the other males of
Tapinoma
in the
Malagasy
region, and 1rs-m+M, free sections of radial sector and cubitus, and also cu-a are weak or
absent
. In all other species in the
Malagasy
region, these veins are distinct (as in
Fig. 59
).
Several of the present results for
Tapinoma
disagree with those in previous studies. A median notch on the anterior margin of the median hypostoma is found in all male
Tapinoma
(
Fig. 65
) save
T
.
subtile
, while the margin in
Shattuck (1992a)
is regarded as entire. The inner margin of the eye in full-face view is concave in several species, while in
Shattuck (1992a)
the margin is regarded as flat. Palpal formula is
6,3 in
a small species,
Tapinoma subtile
(
Fig. 80
), while the formula of
Tapinoma
in
Shattuck (1992a
,
1995
) and
Brandão
et al
. (1999)
is regarded as 6,4. Relative length of the third maxillary palpal segment compared with the fourth varies from shorter than to longer than the third (See
Table 4
). Basal margin of the mandible is partially covered with serrate denticles with a smooth portion on its base (
Fig. 75
), while the margin in
Shattuck (1992a
,
1995
) and
Brandão
et al
. (1999)
is recorded as wholly smooth. The length of the antennal scape is longer than that of flagellomeres 1+
2 in
all males of
Tapinoma
examined, but in some the scapes do not reach the posterior margin of the head in full-face view (as in
Fig. 4
); by contrast, both
Shattuck (1992a
,
1995
) and
Brandão
et al
. (1999)
regarded the scape in
Tapinoma
as exceeding the posterior margin of the head. The relative length of the first flagellomere compared with its width varies from less than 1.5 times to more than three times (See
Table 4
), while the length in
Shattuck (1992a)
is regarded as less than two times. Posterior margin of the mesoscutum is notched medially in one species (
T
. mg10), while the character of the margin in
Shattuck (1992a
,
1995
) and
Brandão
et al
. (1999)
is regarded as entire. A laterally expanded petiole can be seen in a male
Tapinoma
(
T
. mg11), although its dorsum is blunter than that in
Ochetellus
. Abdominal segment III does not always cover the petiole completely by overhanging anteriorly and seems to be nearly vertical in one male (
T
. mg11), although the segment of
Tapinoma
in
Shattuck (1995)
and
Brandão
et al
. (1999)
is regarded as overhanging the petiole, so that the petiole is invisible in dorsal view. The harpago is not separated from the basimere by a membranous region in two species of
Tapinoma
(
T
. mg02 and
T
. mg11) in the
Malagasy
region (
Fig. 29
), while this character of
Tapinoma
in
Shattuck (1992a
,
1995
) and
Brandão
et al
. (1999)
is regarded as divided into two parts separated by a membranous region. The cuspis on the volsella can be found in four (
T
.
melanocephalum
,
T
. mg04,
T
. mg10, and
T
. mg11 as in
Fig. 47
) out of seven
Malagasy
species, while this character is regarded as
absent
in
Tapinoma
by
Shattuck (1992a
,
1995
).
Additional discussion of characters is included in the remarks for
Ochetellus
.