Bacillometroides, a New Genus of Hydrometridae (Heteroptera) for Three Previously Described Species...
Transcript of Bacillometroides, a New Genus of Hydrometridae (Heteroptera) for Three Previously Described Species...
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Bacillometroides, a New Genus of Hydrometridae (Heteroptera)for Three Previously Described Species from South AmericaAuthor(s): John T. Polhemus and Dan A. PolhemusSource: Entomologica Americana, 116(1):58-63. 2010.Published By: The New York Entomological SocietyDOI: http://dx.doi.org/10.1664/09-RA-010R.1URL: http://www.bioone.org/doi/full/10.1664/09-RA-010R.1
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BACILLOMETROIDES, A NEW GENUS OF HYDROMETRIDAE (HETEROPTERA)
FOR THREE PREVIOUSLY DESCRIBED SPECIES FROM SOUTH AMERICA
JOHN T. POLHEMUS1
AND DAN A. POLHEMUS2,3
1Colorado Entomological Museum, 3115 S. York St., Englewood, CO 801132Department of Natural Sciences, Bishop Museum, 1525 Bernice St., Honolulu, HI 96817
Abstract.—The South American genus Bacillometra as previously interpreted does not represent a monophyletic
assemblage, thus Bacillometroides n. gen. is proposed to hold all species previously contained in this genus with the
exception of B. ventralis Esaki, the type species of Bacillometra. The following new combinations are proposed:
Bacillometra fuallagana Drake, 1956 5 Bacillometroides fuallagana (Drake); Bacillometra mulfordi (Hungerford,
1927) 5 Bacillometroides mulfordi (Hungerford); Bacillometra woytkowskii Hungerford, 1935 5 Bacillometroides
woytkowskii (Hungerford). Figures are provided of the dorsal habitus for Bacillometra ventralis and Bacillometroides
woytkowskii, and a distribution map is provided for all species in both genera.
INTRODUCTION
A recent character analysis of taxa held in the
family Hydrometridae has revealed that the
species held in the genus Bacillometra Esaki do
represent a monophyletic assemblage. As a result,
we propose a new genus, Bacillometoides, to hold
three species previously held in Bacillometra.
Although hydrometrids are generally consid-
ered to be inhabitants of calm water habitats,
occurring along the margins of ponds and slow-
moving streams, this is a perception largely
influenced by the habits of the Northern Hemi-
sphere species most familiar to the majority of
American and European entomologists. By con-
trast, tropical hydrometrids exhibit a much wider
range of ecological preferences, including species
that inhabit terrestrial habitats, rheocrenes, and
swift streams. Both Bacillometra and Bacillome-
troides species occupy the latter habitat type,
being confined to rocky upland streams in the
Guiana Plateau and the foothills of the Andes
respectively. Despite their congruent habitat
preferences and superficial morphological similar-
ities, the two genera may not be closely related,
given that they show marked divergence in regard
to several important character systems, including
the spacing of the coxae and the structure of the
antennae.
MATERIALS AND METHODS
All measurements in the descriptions below are
given in millimeters. CL numbers in the material
examined sections refer to a collection locality
coding system used by the authors to cross
reference specimen labels with field notes, habitat
photographs, and other metadata.
TAXONOMY
Bacillometroides, new genus
DESCRIPTION: Long, narrow, of moderate size
(Fig. 1A, B). Head relatively long, about twice the
length of the thorax, anteocular part about twice
postocular length, eyes large; posterior pair of
trichobothria set on, at most, low tubercles;
rostrum long, reaching onto middle of postocular
head; antennae long, about 3/4 of body length,
slender, segment II about 2.5 times longer than
segment I, segment III about 3 times as long as II,
segment IV slightly longer than II. Thorax not
widened posteriorly, greatest width of thorax less
than half of median length; pronotal lobe short,
extending posteriorly over mesonotum, metano-
tum exposed, scutellum exposed; without any
trace of wing pads in apterous form, macropter-
ous wings with 2 longitudinal veins and two cross
veins, Sc and C separated on basal one fourth
(Fig. 1B). Head and thorax without black denti-
cles. Abdominal mediotergites longer than broad.
Legs slender, thickened basally but not incrassate,
not threadlike distally; middle coxae farther from
hind coxae than fore coxae.
3 E-mail address for correspondence: bugman@
bishopmuseum.org
Entomologica Americana 116(1/2):58–63, 2010
TYPE SPECIES: Hydrometra mulfordi Hungerford,
1927.
DISCUSSION: The genus Bacillometroides, con-
taining three described species formerly held in
Bacillometra (all represented by both males and
females in JTPC), may be differentiated from the
latter genus by the following divergent character
states:
1) Posterior pair of trichobothria set on large
tubercles (versus set on low tumesences in
Bacillometra);
2) Appressed hairs on body fine and setiform
(versus occurring in the form of small black
denticles in Bacillometra);
3) Greatest width of thorax less than half the
length along midline (versus greater than half
the length along midline in Bacillometra)
4) Abdominal mediotergites longer than broad
(versus broader than long in Bacillometra);
5) Middle coxae set closer to fore than to hind
coxae (versus approximately equidistant be-
tween fore and hind coxae in Bacillometra).
Andersen (1977, 1982), and Andersen and
Grimaldi (2001) analyzed the phylogeny of
Hydrometridae and provided a higher level
classification for the group that was identical in
each case in regard to currently extant taxa.
Although a complete phylogenetic reanalysis of
Fig. 1. Dorsal habitus views of Bacillometra and Bacillometroides species. A. Bacillometroides woytkowskii
(Hungerford), wingless female, legs omitted. B. Bacillometroides woytkowskii (Hungerford), winged male. C.
Bacillometra ventralis Esaki, winged male. A and B after Hungerford, 1935; C after Esaki, 1927.
2010 BACILLOMETROIDES, A NEW GENUS OF HYDROMETRIDAE 59
Hydrometridae is beyond the scope of the current
paper, four of the characters noted above as being
diagnostic for separation of Bacillometra and
Bacillometroides were also used in all three of
these previous phylogenetic analyses, and provide
a strong argument for separate generic status of
these two groups from a phylogenetic standpoint.
In Bacillometra as defined herein (note that
Bacillometra as treated by Andersen and Ander-
sen and Grimaldi was a composite of Bacillometra
and Bacillometroides), Andersen’s Character 1
(trichobothria), exhibits a plesiomorphic condi-
tion (trichobothria set on low tumescences) that
would group it in the Heteroclepinae. For
Andersen’s Character 3 (form of hairs on body),
Bacillometra as defined herein exhibits an apo-
morphic condition that would place it in the
Hydrometrinae. For Andersen’s Characters 14
and 15, Bacillometra as defined herein exhibits
plesiomorphic character states that would exclude
it from the terminal clade containing Bacillome-
troides and Hydrometra. Based on the preponder-
ance of character states, Bacillometra as we have
redefined it would thus branch off at an interme-
diate node within the Hydrometrinae, with
retention of a single plesiomorphic character state
in regard to the trichobothrial tubercles.
By contrast, Bacillometroides exhibits apo-
morphic character states for Andersen’s Charac-
ters 1, 14 and 15 that would place it in a terminal
clade of the Hydrometrinae as shown on Ander-
sen’s (1982) tree, with Hydrometra as its sister
group. Bacillometroides does exhibit a plesio-
morphic state for Andersen’s Character 3 (body
hairs fine and setiform) that does not conform to
the typical ground plan for the Hydrometrinae,
but it is most parsimonious to conclude that this
aspect of chaetotaxy has undergone a reversal of
character state.
In order to force both Bacillometra and
Bacillometroides into the same clade (much less
the same genus) on Andersen’s 1982 tree, one
would need to accept three character state
reversals in Bacillometra and one character state
reversal in Bacillometroides. We do not consider
this a parsimonious hypothesis, and therefore
propose separate generic status for Bacillome-
troides.
The genus Bacillometroides as proposed herein
contains three described species: B. fuallagana
Drake, 1956; B. mulfordi (Hungerford, 1927); and
B. woytkowskii Hungerford, 1935.
ETYMOLOGY: The generic name Bacillometroides
is derived from its similarity to the genus
Bacillometra. Gender feminine.
DISTRIBUTION: South America (Fig. 2).
Bacillometroides fuallagana (Drake),
new combination
Bacillometra fuallagana Drake, 1956: 155
DISCUSSION: Bacillometroides fuallagana occurs
on the eastern slope of the Andes, and is so far
known only from the Huallaga River basin of
Peru.
MATERIAL EXAMINED: PERU, Dept. Huanuco: 1
macropterous male (genitalia absent), Cucharas
R., Fuallago [NW of Tingo Maria, 520 m.], July
1954, FLW (paratype, JTPC); 1 macropterous
male, 1 macropterous female, same data as
preceding but lacking paratype labels (JTPC); 1
macropterous male, 1 macropterous female, Hua-
nuco, 700 m., October 1961, Bacillometra fualla-
gana Drk det. Nieser (JTPC); 3 macropterous
males, 4 macropterous females, Huallaga River at
Cucharas [NW of Tingo Maria], rocks in fast
water, Peru S. A., February–August 1954, F.
Woytkowski, Note 541 (JTPC).
ECOLOGICAL NOTES: Additional details regard-
ing the type locality may be found in Woytkowski
(1978).
Bacillometroides mulfordi (Hungerford),
new combination
Bacillometra mulfordi (Hungerford, 1927)
Hydrometra mulfordi Hungerford, 1927: 187
Bacillometra mulfordi, Hungerford, 1935: 118
SUPPLEMENTAL DESCRIPTION: Micropterous male:
Length 10.57, maximum width 0.64.
Color: Ground color brown; abdominal tergites
light brown, matte. Head tinged with blackish
ventrally, and dorsally anterad of eyes. Thorax
dorsally with median longitudinal frosted stripe;
each segment of connexiva dorsally with frosted
area anteriorly. Venter of thorax and abdomen
light, with dark median stripe on abdomen. Legs
light brown to brown, darker distally, antennae
brown to dark brown; coxae, trochanters mostly
light brown, similar to bases of femora.
Structure: Head relatively long (5.80), widest at
antennal tubercles (0.57); set with short bristly
setae beneath; gular lobe large, rounded; rostrum
reaching well caudad of eyes, halfway to proster-
num; ratio anteocular/postocular portions: 3.62/
1.64; interocular space/width of an eye: 0.10/0.26;
60 ENTOMOLOGICA AMERICAN Vol. 116(1/2)
anteclypeus small, broadly rounded anteriorly.
Antennal formula I:II:III:IV; 1.02: 2.54: 5.04:
1.94. Pronotum set with very small shallow
frosted foveae. Pronotum length 1.14; remainder
of thorax 0.88 (to lateral suture behind metaceta-
bulae); abdomen length 4.96. Wing pads, if
present, very small, not visible, hidden under
pronotum. Thoracic, abdominal sternites with
Fig. 2. Distribution of Bacillometra and Bacillometroides species in South America.
2010 BACILLOMETROIDES, A NEW GENUS OF HYDROMETRIDAE 61
short bristly setae, about equally dense on all
segments. Distance between anterior and middle
coxae (measured between closest margins) 0.44;
between middle and hind coxae 0.59. Acetabulae
without obvious pits. Venter without evident
black denticles.
Proportions of legs as follows: Femur, tibia,
tarsal I, tarsal II, tarsal III of fore-leg, 4.73: 5.26:
0.08: 0.28: 0.23; of middle-leg, 5.44: 5.99: 0.08:
0.18: 0.21; of hind-leg, 4.59: 9.07: 0.15: 0.18: 0.21.
First abdominal segment short, transverse,
delineated by a pair of pits posteriorly. Male
abdominal sternite VI with two widely set spines
on posterior margin, each about equidistant from
midline to connexival margin; segment VIII with
slight ventral keel, modified, with distal process
ventrally. Seventh sternite without modifications.
Micropterous female: The two distinct spines
described by Hungerford (1927) as being on the
‘‘caudal margin of the sixth abdominal segment’’
are actually on the caudal margin of sternite VII.
DISCUSSION: This species was originally de-
scribed from a series of six females taken by W.
H. Mann at Huachi, on the Rio Beni in Bolivia.
To date the male has remained unknown, but we
are now able to provide a supplemental descrip-
tion of this form.
MATERIAL EXAMINED: BOLIVIA: Dept. Guanay:
3 micropterous males, 2 micropterous females,
Tres Estero, 19–25 August 1989, L. E. Pena
(JTPC).
Bacillometroides woytkowskii (Hungerford),
new combination
Bacillometra woytkowskii Hungerford, 1935: 119
DISCUSSION: Bacillometroides woytkowskii was
described from a large series of specimens
collected by F. Woytkowski on the Rio Rimac,
in the desert foothills of the Andes east of Lima.
Hungerford (1935) also quoted the detailed field
notes provided by Woytkowski, which still remain
the best overall description of habits and habitat
provided to date for any Bacillometroides species.
MATERIAL EXAMINED: PERU: Dept. Lima: 1
macropterous male, 1 macropterous female, Re-
cardo Palma, 44 km. E. of Lima (see letter),
1250 m., 27–29 November 1934, F. Woytkowski
(paratypes, JTPC); 3 micropterous males, 50 km.
E. of Lima, 18 October 1970, J. Sedlacek (JTPC);
1 micropterous male, Quebrada Verde, Lima,
fern, 28 August 1949, leg. Weyrauch (JTPC); 1
micropterous male, Rio Mala, 6 April 1952, leg.
Weyrauch, 5692-D (JTPC); 1 micropterous fe-
male, 120 km. S. of Lima, 350 m., 24 September
1951, leg. Weyrauch, 5692-C (JTPC); 1 micro-
pterous female, Rio Lurin at Cieneguilla, SE of
Lima, 250 m., water temp. 19uC., 3 August 1989,
CL 2443 D. A. and J. T. Polhemus (JTPC).
BACILLOMETRA ESAKI 1927
DISCUSSION: The genus Bacillometra was de-
scribed by Esaki (1927:1) and compared to the
genus Hydrometra. The relationship of these two
genera was discussed further by Hungerford
(1935:117), who provided a key to the three
species included in the former genus at that time.
Bacillometra ventralis Esaki
Bacillometra ventralis, Esaki, 1927: 2
SUPPLEMENTAL DESCRIPTION: Macropterous fe-
male: Body length 9.20 mm, maximum width
1.20 mm. Coloration similar to that of male as
described by Esaki (1927).
Antennae with length of segments I–IV 5 0.50;
1.20; 2.90; 1.90. Segment IV bulbous distally (also
in male).
Thorax length 1.30; maximum width (across
humeri) 1.10.
Legs with distal anterior femur reaching slightly
beyond apex of head; posterior femur reaching
beyond end of abdomen.
Abdomen with tergite VIII large and angled
upward; ovipositor and gonopophyses not prom-
inent.
DISCUSSION: This species was originally de-
scribed from a single male in the Paris Museum
collection, taken by F. Geay at Comopi, French
Guiana in 1900. The species remained obscure
until a series of both sexes was taken by the first
author along a rocky stream near Puerto Aya-
cucho, Venezuela. Based on this material, a
supplemental description of the previously un-
known female is provided, concentrating on
diagnostic characters, including some (such as
the terminal antennal segments) that were missing
in Esaki’s holotype.
The specimens listed below from Venezuela are
the first reported since the type.
MATERIAL EXAMINED: VENEZUELA: Amazo-
nas: 7 macropterous males, 3 macropterous
females, Rio Cataniapo at Las Pavas, 23 January
1989, CL 2377, J. T. Polhemus (JTPC).
ECOLOGICAL NOTES: The Venezuelan specimens
were taken from mostly vertical faces of mid-
62 ENTOMOLOGICA AMERICAN Vol. 116(1/2)
stream boulders at the Rio Cataniapo near Puerto
Ayacucho, some in sun and some in shade. At this
collection locality the Rio Cataniapo was approx-
imately 70 m wide and quite deep. The north
shore from which the stream was accessed was
gentle, and the current was not strong, but as a
result it was the favored place among the local
women for washing clothes, and was therefore
quite polluted with soap, thus the collecting along
the banks was poor. For this reason, the first
author decided to swim out to a set of midstream
boulders with a net and pooter (aspirator).
Fortunately, these large midstream boulders
offered adequate footing in the otherwise deep
stream, and allowed inspection of their surfaces,
which revealed that they harbored Bacillometra
ventralis. These hydrometrids ran over the steep
or vertical rock faces of the boulders in the area
above the waterline, and were somewhat difficult
to capture. None ventured onto the water surface
itself, even when disturbed, so it was concluded
that they do not commonly inhabit the surface
film. In addition to Bacillometra ventralis, these
midstream boulders supported several species of
Microvelia, as well as Ochterus and Mesoveloidea
species.
KEY TO SPECIES OF BACILLOMETRA
AND BACILLOMETROIDES
1. Coxae equally spaced; antennal segment IV
bulbous distally; Guiana Plateau . . . . . . . . .
. . . . . . . . . . . . . . . . . Bacillometra ventralis Esaki
– Middle coxae farther from hind coxae than fore
coxae; antennal segment IV filamentous, not
expanded distally; Andes . . . . (Bacillometroides) 2
2. Male ventrite VII bearing a prominent trian-
gular spine on each side lateroventrally; female
with abdominal segment VII bearing a caudally
directed lateral spine on each side; Bolivia . .
. . . . . . . . . . . . . . . . . . B. mulfordi (Hungerford)
– Male ventrite VII lacking lateroventral spines,
although ventrite VIII may possess a single
medial spine posteroventrally; female abdomi-
nal ventrite VIII bearing a single spine or small
protruberance medially, but lacking paired
lateral spines; Peru . . . . . . . . . . . . . . . . . . . . . . 3
3. Male with abdominal ventrite VII bearing long
setae; male abdominal ventrite VIII bearing a
spine posteromedially; female with abdominal
segment VIII bearing a long, sharp spine
posteromedially . . . . B. woytkowskii (Hungerford)
– Male with abdominal ventrite VII lacking long
setae; male abdominal ventrite VIII unmodi-
fied, lacking spines; female with abdominal
segment VIII bearing a small angulate tubercle
posteromedially . . . . . . . . . B. fuallagana (Drake)
ACKNOWLEDGMENTS
We wish to thank Dr. Paul Spangler, formerly ofthe Smithsonian Institution, Washington, DC, forcoordinating the logistics for the trip to southernVenezuela during which the first author was able to
collect specimens of Bacillometra ventralis, therebyproviding the impetus for this study.
LITERATURE CITED
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Received 2 October 2009; accepted 17 March 2010
2010 BACILLOMETROIDES, A NEW GENUS OF HYDROMETRIDAE 63