A review of the Pseudomyrmex ferrugineus and Pseudomyrmex goeldii species groups: acacia-ants and relatives (Hymenoptera: Formicidae)
Author
Ward, Philip S.
text
Zootaxa
2017
4227
4
524
542
journal article
36702
10.11646/zootaxa.4227.4.3
6274d9b8-0067-48bd-a403-b7522816c58d
1175-5326
306006
68B993FB-9D8C-4950-9BF8-0D40EDFB8C78
Pseudomyrmex micans
Ward
,
sp. nov.
(
Fig. 6
)
Pseudomyrmex goeldii
;
Chomicki
et al.
(2015
: 4
) (misidentification).
Type
material
.
Holotype
worker
.
PERU
San Martín
:
Tarapoto
,
350 m
, 6°29ʹS, 76°22ʹW,
25 Aug 1986
, ex dead twig, edge of second-growth rainforest,
P. S. Ward
PSW08734 (
MZSP
) (CASENT0794101)
.
Paratypes
. Series of workers,
1 male
, same data as holotype (
CASC
,
JTLC
,
MCZC
,
PSWC
,
UCDC
,
USNM
).
Other material examined
(
PSWC
).
BOLIVIA
Santa Cruz
:
11 km
NE
Aserradero Moira
,
180 m
(
P. S. Ward
).
Worker measurements
(n = 6). HL 0.67–0.74, HW 0.52–0.55, MFC 0.007–0.009, LHT 0.39–0.42, CI 0.74– 0.80, REL 0.59–0.61, REL2 0.75–0.80, FCI 0.013–0.016, FI 0.53–0.55, PLI 0.64–0.69, PWI 0.56–0.63.
Worker diagnosis
. Small species (HL 0.67–0.74, HW 0.52–0.55) with elongate head and eyes (CI 0.74–0.80, REL 0.59–0.61, REL2 0.75–0.80); masticatory margin of mandible with 5 teeth; palp formula 4,3; juncture between dorsal and declivitous faces of propodeum only weakly angulate, not producing lateral tubercles; anterodorsal face of petiole ascending gently (
Fig. 6
b). Head smooth and shiny with scattered fine punctulae; pronotum similar, remainder of mesosoma becoming sublucid, with coriarious-imbricate sculpture on most surfaces, but with shining areas on the mesopleuron and metapleuron; petiole, postpetiole and gaster with moderately dense pubescence. Standing pilosity sparse (MSC 2); paired erect setae present on pronotal humeri, petiole and postpetiole. Dark brown, mandibles, frontoclypeal complex and tarsi lighter; pronotum, petiole and postpetiole sometimes a lighter medium- to yellowish-brown.
FIGURES 4–6.
Pseudomyrmex goeldii
group, workers, full-face dorsal view of head (a) and lateral profile of body (b). 4,
P. goeldii
, Brazil (CASENT0907543); 5,
P. laevifrons
, Bolivia (CASENT0762973); 6,
P. micans
, Peru (CASENT0794101). Images from AntWeb (www.antweb.org); photographers Will Ericson (4) and Matthew Prebus (5, 6).
FIGURES 7–8.
Pseudomyrmex goeldii
group, workers, full-face dorsal view of head (a) and lateral profile of body (b). 7,
P. obtusus
, Venezuela (CASENT0794100); 8,
P. parvulus
, Brazil (CASENT0762994). Images from AntWeb (www.antweb.org); photographer Matthew Prebus.
Comments
. Based on the weakly angulate propodeum this species was initially considered conspecific with
P. goeldii
(and called this in
Chomicki
et al.
2015
), but a more careful examination of relevant material reveals substantial differences:
P. micans
is smaller in size (HW 0.52–0.55 versus HW
0.65–0.66 in
the three
syntype
workers of
goeldii
), and has more elongate eyes (REL 0.59–0.61 versus 0.55–0.56), a shorter petiole (PLI 0.64– 0.69 versus 0.51–0.59), and a more shiny mesosoma.
P. micans
appears to be closely related to
P. laevifrons
, differing primarily by the less pronounced angular juncture of the dorsal and declivitous faces of the propodeum; by the weaker body sculpture, especially on the metapleuron, which is more strongly shining; by slightly lower REL2 values (see above); and by the shape of the petiole, which is lower, wider, and with a more gently sloping anterodorsal face (compare
Figs 5
b and 6b). Collections from
Peru
and
Bolivia
can be separated into one or the other of these two forms, based on the features listed above. This includes diagnostic differences in petiolar metrics: PLI
0.72–0.80 in
P. laevifrons
(n = 5) versus
0.64–0.69 in
P. micans
; DPW/
PH
0.76–0.85 in
P. laevifrons
versus
0.88–0.92 in
P. micans
. In other parts of the range of
P. laevifrons
, where
P. micans
is apparently absent, the petiolar diagnostics break down, and some workers show a weakening of the pronounced angle at the juncture of the dorsal and declivitous faces of the propodeum. One interpretation of this pattern is that
P. laevifrons
ranges from Central America to
Bolivia
and central
Brazil
, undergoing character displacement where it overlaps with the more southern species,
P. micans
. An alternative hypothesis is that the species are distinct in some areas but that differences are obscured by gene flow elsewhere. The entire complex of populations would benefit from a focused phylogenetic analysis.
Distribution and biology
. As currently conceived
P. micans
is known only from rainforest sites in
Peru
(nest ex dead twig, edge of second-growth rainforest) and
Bolivia
(workers foraging on recent
Tabebuia
and
Hymenaea
treefalls).