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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

Andersen, N. M. 1977. A new and primitive genus and

species of Hydrometridae (Hemiptera, Gerro-

morpha) with a cladistic analysis of relationships

within the family. Entomologica Scandinavica 8:

301–316.

Andersen, N. M. 1982. The semiaquatic bugs (Hemip-

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Biogeography and classification. Entomono-

graph 3. 455 pp.

Andersen, N. M. and D. Grimaldi. 2001. A fossil water

measurer from the mid-Cretaceous Burmese

amber (Hemiptera, Gerromorpha: Hydrometri-

dae). Insect Systematics and Evolution 32:

381–392.

Drake, C. J. 1956. New Neotropical Hydrometridae

(Hemiptera). Proceedings of the Biological Soci-

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Esaki, T. 1927. An interesting new genus and species of

Hydrometridae (Hem.) from South America. The

Entomologist 60: 1–4.

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1922. Proceedings of the Entomological Society

of Washington 29(8): 187–191.

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Peru (Hemiptera, Hydrometridae). Revista de

Entomologia 5(2): 117–123.

Woytkowski, F. 1978. Peru, My Unpromised Land

(Peru, moja ziemia nieobiecana). Translated from

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Scientific, Technical and Economic Information,

Warsaw. 231 pp.

Received 2 October 2009; accepted 17 March 2010

2010 BACILLOMETROIDES, A NEW GENUS OF HYDROMETRIDAE 63