Taxonomic clarification of two Nearctic Strumigenys (Hymenoptera: Formicidae)
Author
Booher, Douglas B.
text
Zootaxa
2019
2019-09-04
4664
3
401
411
journal article
25617
10.11646/zootaxa.4664.3.7
e10c309a-3306-481c-b2bb-e3c4b5431e4e
1175-5326
3385595
E390FBF1-D445-40C1-9CA8-CA7CF8945A03
Strumigenys pilinasis
Forel 1901
(
Figure 1
)
Strumigenys clypeata
var.
pilinasis
Forel 1901
, 45:339.
Lectotype
worker (here designated from a unique
syntype
):
Washington
, D.C. (Forel) [MHNG, CASENT0909339, AntWeb.org image examined]. Raised to species:
Wesson & Wesson, 1939: 109
. In
Strumigenys
(
Cephaloxys
)
:
Emery, 1924: 325
; in
Strumigenys
(
Trichoscapa
)
:
Smith, 1947: 587
; in
Smithistruma:
Smith, 1951: 827
;
Brown, 1953: 60
; in
Pyramica
:
Bolton, 1999: 1673
; in
Strumigenys
:
Baroni Urbani & De Andrade, 2007: 126
.
Strumigenys ohioensis
Kennedy & Schramm, 1933: 98
, figs. 1, 2.
Holotype
worker:
Ohio
, Miegs County, Tuppers Plains (Schramm) [MCZC, examined]. Description of queen, male:
Brown, 1953: 87
. In
Strumigenys
(
Cephaloxys
)
:
Wesson & Wesson, 1939: 108
; in
Strumigenys
(
Trichoscapa
)
:
Smith, 1947: 587
;
Creighton, 1950: 308
; in
Smithistruma
:
Smith, 1951: 828
;
Brown, 1953: 87
; in
Pyramica
:
Bolton, 1999: 1673
; in
Strumigenys
:
Baroni Urbani & De Andrade, 2007: 125
.
New Synonym
.
Strumigenys
(
Cephaloxys
)
manni
Wesson & Wesson, 1939: 97
, pl. 3, fig. 3.
Holotype
worker:
Ohio
, Pike County, near Sinking Spring [MCZC, examined]. Junior synonym of
ohioensis
:
Smith, 1951: 828
;
Brown, 1953: 87
.
New Synonym
.
Diagnosis.
Strumigenys pilinasis
is one of the most easily diagnosed Nearctic
Strumigenys
and can be distinguished from all other North American species by the unique clypeal pilosity.
Strumigenys pilinasis
is the only species with simple coarse hairs extending from the lateral border of clypeus that are strongly J-shaped (
Figure 1a
). These hairs, although variable, have several to many inclined anteriorly at their bases, strongly curved along their mid-length, and directed posteriorly at their apices. These hairs are simple and coarse to extremely narrowly expanded, always more cylindrical than spatulate along their entire length. The brief description given below is in agreement with descriptive treatments of the junior synonyms
S. ohioensis
and
S. manni
(
Kennedy and Schramm 1933
,
Wesson & Wesson 1939
,
Bolton 2000
).
Lectotype
measurements.
Measurements taken from images (AntWeb 2019).
HL = 0.577; HW = 0.400;
ML
= 0.123;
PW
= 0.280; SL = 0.297; TL = 2.120;
WL = 0.581; CI = 69; MI = 21; SI = 74.
Description
. Head. Mandibles with basal broad triangular lamella, half of which is concealed by clypeus and half is visible in full frontal view; lamella followed by five principle teeth; counting from base of mandible tooth one, two, and four similarly sized and smaller than tooth three; tooth five as long or longer than first two teeth; tooth three being obviously longer than any other tooth. Clypeus slightly wider (0.223) than long (0.210) and narrowing anteriorly toward mandibles; nearly equal in width as distance between mandible insertions; anterior border between mandible insertions convex. Scape narrow and not expanded at subbasal bend; sharply bent just above condyle forming nearly a 90° angle. Scape nearly ¾ the width of head (SI = 74). Mesosoma in profile pronotum and mesonotum broadly convex; metonotal groove weakly impressed to absent; propodeum flat. Propodeal spine triangular and well formed (ca.
0.055 mm
long) followed ventrally by a narrowing lamella along the declivitous face of propodeum.
Sculpture. Clypeus and head heavily punctate to reticulopunctate. Dorsum and side of pronotum with reticulopunctate sculpture similar to that on dorsum of head. Most of the side of mesonotum, pleurae, and propodeum shining with peripherally punctate sculpture. Dorsum of petiole with reticulopunctate sculpture, disc of postpetiole smooth and shining. Basigastral costulae well developed and extending nearly one third of the length of the first gastral tergite. The rest of the abdomen smooth and shining.
Pilosity. Hairs on lateral margins of clypeus J-shaped and pointing posteriorly at apices. Hairs on anterior margins variable and tending to curve ventrally. Hairs on clypeal dorsum variably oriented, but tending to arch anterolaterally, extending anteriorly at their base and curving laterally to posterolaterally along midlength. Hairs on scape similar in shape to clypeal dorsum and variably directed with some hairs directed toward base of scape, some directed ventrally, but most hairs arched anterolaterally and directed towards apex of scape. Head, mesosomal dorsum, dorsum of petiolar node, and exposed disc postpetiole with abundant arched coarse to narrowly expanded hairs. On the dorsum of head, these hairs are directed medially and on petiolar and postpetiolar nodes they are directed posteriorly. Differentiated elongate to flagellate hairs at humeral angles and basitarsi present and apparent in most non-type specimens, not apparent on
type
images. However, these hairs are easily abraded and are often missing and in the case of the
type
specimen the excess of glue covering the basitarsi obscure examination and are not important diagnostic characters for
S. pilinasis
.
Comments.
Strumigenys pilinasis
is a common eastern North American litter-dwelling ant that has been collected in contiguous states between
Connecticut
and
Florida
and west to eastern
Texas
and
Oklahoma
. Throughout its range, unlike
S. brevisetosa
,
pilosity and morphology vary little—making it easily identifiable across its range. Of 9,013 databased records of Nearctic
Strumigenys
, in a database maintained by the author,
S. pilinasis
ranked fourth with
646 specimen
records (unpublished data). In two studies of
Strumigenys
found nesting in empty fallen nuts in forests near
Washington D.C.
(near
lectotype
collection),
S. pilinasis
was by far the most common species (
Duffield & Alpert 2011
,
Booher et al. 2017
).
FIGURE 1
. Holotype worker of
Strumigenys pilinasis
[MHNG: CASENT0909339] Photographed by Zach Lieberman, Ant- Web.org.
Kennedy and Schramm provided an inaccurate illustration of
S. ohioensis
. They described and illustrated hairs projecting from the lateral borders of the clypeus that were relatively short and directed anteriorly, when in fact these hairs are variable and several to many are strongly J-shaped—being inclined anteriorly at their bases, strongly curved along their mid-length, and point posteriorly at their apices. In 1939, Wesson & Wesson described
S. manni
(new junior synonym
S. pilinasis
) and it was the first description to accurately describe the key and unique distinguishing character of this species, the J-shaped clypeal pilosity. However, Wesson & Wesson did not realize
S. manni
was synonymous with
S. ohioensis
because they did not examine the type specimens of
S. ohioensis
and only relied on the original description and illustrative work (
Kennedy and Schramm 1933
).
Brown (1953)
provided greater detail and a full accounting of this set of events when he listed
S. manni
as a junior synonym of
S. ohioensis
, but Brown did not examine the
S. pilinasis
holotype
(
Brown 1953
).