Table Of ContentPROC. ENTOMOL. SOC. WASH.
lOOd), 1998. pp. 25-31
NYSIUSAA (HETEROPTERA: LYGAEIDAE), A NEW SPECIES OF
MICROPTEROUS WEKIU BUG FROM THE SUMMIT OF
MAUNA LOA VOLCANO, HAWAII
Dan a. Polhemus
Department of Entomology, MRC 105, National Museum of Natural History. Smith-
sonian Institution, Washington, DC 20560, U.S.A. (e-mail: [email protected])
—
Abstract. Nysiiis aa, a micropterous lygaeid bug, is described from the upper slopes
of Mauna Loa volcano on the island of Hawaii. This new species appears to be the sister
species of Nysius wekiuicola Ashlock and Gagne, which is endemic to aeolian desert
habitats in the summit region of adjacent Mauna Kea volcano. Detailed morphological
comparisons between the two species are presented, accompanied by a distribution map
and figures of key characters.
Key words: Lygaeidae. micropterous, alpine, aeolian, Hawaii, Mauna Kea, Mauna Loa
TTie Wekiu Bug, Nysius wekiuicola. a mi- Loa thus became a question of some im-
cropterous lygaeid endemic to the aeolian portance in terms ofconservation planning,
m
deserts surrounding the 4206 (13,796 ft.) and the existence ofthe Howarth and Stone
summit of Mauna Kea volcano on the is- material from the latter mountain was
land of Hawaii, was described by Ashlock brought to the author's attention by Betsy
and Gagne (1983). In the same paper, these Gagne, of the State of Hawaii's Natural
authors commented on anecdotal accounts Area Reserves System, a unit of which in-
of similar bugs occurring on the 4170 m cludes portions of the Mauna Kea summit.
(13,680 ft.) summit of Mauna Loa volcano The Mauna Loa specimens were subse-
to the southwest. In 1985, Frank Howarth quently located in the collections of the
of the Bishop Museum and Fred Stone of Bishop Museum and analyzed in detail;
the Hawaii Community College at Hilo em- they have proven to represent adistinct new
placed pitfall traps at 3450 m (11,316 ft.) species, described below.
elevation on Mauna Loa, and were able to All measurements in the following de-
capture a short series of micropterous ly- scription are in millimeters.
gaeids. In general appearance these Mauna
Loa bugs were similar to the Wekiu Bugs Nysius aa Polhemus, new species
from Mauna Kea, and the material was not (Figs. 1, 3, 4, 7, 9)
—
analyzed further at that time. In the mid- Diagnosis. A small, fuzzy, dark-colored
1990's, with the continuing expansion of micropterous lygaeid bug. similar in gen-
observatory facilities on the summit of eral appearance to N. wekiuicola Ashlock
Mauna Kea, concerns were raised regarding and Gagne, but easily separable on the basis
the progressive destruction of Wekiu Bug of the following characters: body in males
habitat on that mountain due to construction pear-shaped, with sides of abdomen dis-
activities. The possible presence of addi- tinctly outwardly convex (versus nearly
tional Wekiu Bug populations on Mauna parallel sided in N. wekiuicola: compare
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26 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON
Figs. 1-2. Wekiu Bugs, males, dorsal habitus. 1. Nyxiiis aa. 2. N. wekiuiccUi. showing overall body shape
forcomparison to Fig. 1 (appendages omitted). As noted by Ashlock andGagn^ (1983). the abdomensofWekiu
Bugs are strongly physogastric. swelling after feeding, and collapsing drastically in all dry mounted specimens
except those which have been run through acritical pointdrier Asaresult, these insects aredifficultto illustrate,
with the best results coming from specimens in alcohol immersion. Fig. 1 ofAshlock and Gagne (1983)depicts
a specimen ofA', wekiuicala with the abdomen swollen, while this figure depicts the abdomen in a more relaxed
slate that better displays the actual shapes ofthe lateral paralergites for comparison with A', aa.
Figs. I and 2); female abdominal ventrite medium brown, head and pronotum black-
IV with only a weak medial incision at base ish, appendages yellowish brown distally.
of ovipositor (versus incised for nearly half Head: Length 0.75, width 0.75, general
its length in N. uekiiiicola: compare Figs. coloration black, with a yellowish brown
3 and 4); female abominal tergite VIII con- longitudinal median line, this line most
sisting of two roughly quadrate plates with prominent on posterior half of head, often
the lateral margins straight (versus plates of becoming obscure ahead ofeyes, small dark
a different shape with the lateral margins yellowish marks also present along inner
angulate in A', wekiuicola: compare Figs. 5 margins of eyes; dorsal surface slightly el-
and 6); and male paramere with a narrow evated between eyes, lightly rugose, thickly
pointed tip (versus a broader, more rounded clothed with recumbent to semi-recumbent
tip in N. wekiuicola; compare Figs. 7 and pale pubescence; apex ofclypeus with erect
8). pale hairs; anteocular length 0.37, nearly
Description. Micropteroiis male: Over- 1.7X length of an eye; eyes reddish brown,
all length 3.75; maximum width (across ab- eye length 0.22, width 0.15; interocular
domen) 1.50. General coloration dark to space 0.42; ocelli small, dark yellow; buc-
a
,
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cula low, gradually tapering in height with- coxae, trochanters, tibiae and tarsi yellow-
out abrupt change in width to base of head; ish brown; all segments clothed with fine,
rostrum brown, reaching to hind coxae, seg- pale, semi-recumbent setae intermixed with
ment I nearly reaching to base ofhead, seg- scattered longer erect pale setae; fore tibia
ment lengths (from base) 0.57, 0.55, 0.40, slightly expanded on distal '/;. Lengths of
0.30; antennae long, slender, segments I and leg segments as follows: fore femur, tibia,
IV only slightly thicker than segments II tarsal I, tarsal II, tarsal III = 1.07, 1.27,
and III, segments I—III brown, bearing erect 0.37, 0.16, 0.25; middle femur, tibia, tarsal
pale setae, these setae slightly longer than I, tarsal II. tarsal III = 1.25, 1.35. 0.37,
diameters of these segments, segment IV 0.17, 0.25; hind femur, tibia, tarsal I, tarsal
yellowish brown, bearing erect pale setae IL tarsal III = 1.50, 1.80, 0.52, 0.21, 0.25.
intermixed with a dense covering of short, Male paramere coming to an elongate,
semi-recumbent pale setae, lengths of seg- pointed tip, shape as in Fig. 7.
ments I-IV = 0.44, 0.80, 0.56, 1.37. Micropterousfemale: Length 4.30; max-
Pronotum: Length (midline) 0.50, max- imum width 1.90. Similar to male in gen-
imum width 0.75, dark brown to blackish, eral structure and coloration with following
narrowly dark yellow along extreme ante- exceptions: abdominal tergite VIII narrow
rior margin; dorsal surface thickly clothed and transverse, consisting ofa pair ofquad-
with recumbent to semi-recumbent pale pu- rate plates (Fig. 5); abdominal ventrite IV
bescence; disc deeply and coarsely rugose; weakly indented medially on its posterior
lateral pronotal margins weakly constricted margin ahead of base of ovipositor, this in-
near middle, barely defining anterior and dentation less than half length of segment
posterior lobes. as taken along its lateral margin (Fig. 3);
Scutellum: Length (midline) 0.25, max- abdominal ventrite V deeply cleft for nearly
imum width 0.50, dark brown to blackish, its entire length to accomodate ovipositor
bearing a raised, brown, longitudinal medial sheath (Fig. 3)—.
carina; surface thickly clothed with recum- Etymology. The name "aa" is a noun
bent to semi-recumbent pale pubescence. in apposition and refers to the flows of a'
Hemelytra: Micropterous, brown, lighter lava where this species—dwells.
near tips, length 0.50, reaching only to ab- Material exainined. Holotype, microp-
dominal tergite I, not touching along body terous 6: HAWAIIAN ISLANDS, Hawaii
midline; clavus weakly distinct from cori- Is., N. side of Mauna Loa, above MLO
um basally, venation obscure except for ex- [Mauna Loa Observatory], 3450 m ( 1 1,316
treme basal portion of subcosta; surface ft.), 30 March-13 April 1985, from baited
dull and impunctate, bearing recumbent to pitfall trap #3, F G. Howarth, D. G. Ho-
semi-recumbent pale pubescence. warth, V. M. C. Howarth and F. D. Stone,
Abdomen: Lateral margins outwardly deposited in the Bishop Museum, Honolulu
convex, length 2.27, maximum width 1.73; (BPBM). Paratypes (all micropterous): 4 S
tergites brown, with I, VI and VII darker, 3 9, same data as holotype, deposited in
all tergites bearing scattered fine, pale, the Bishop Museum and the National Mu-
semi-recumbent, setae, and separated by seum of Natural History, Smithsonian In-
membranous areas; lengths oftergites I-VII stitution, Washi—ngton, D.C.
(midline) = 0.25, 0.20, 0.42, 0.45. 0.27. Discussion. The flightless lygaeids in-
0.12, 0.31; paratergites dark brown, bearing habiting the highest summits ofHawaii is-
recumbent to semi-recumbent pale pubes- land have come to be commonly referred
cence; ventral surface dark brown, shining, to as "Wekiu Bugs" by Hawaiian ento-
bearing scattered long, fine, pale, semi-re- mologists, "wekiit^' meaning "summit"
cumbent setae. in the Hawaiian language. Within the
Legs: Long and slender, femora brown; large and speciose genus Nysiiis the Wek-
28 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON
Figs. 3-8. Female abdominal structures (3-6) and male parameres (7-8) ofHawaiian alpineNysiiis species.
3,Nysiiisaa. terminal abdomen, ventral view (notedegreeofmedial incisionon ventrite IVatbaseofovipositor).
4, N. wekiiiicvla. terminal abdomen, ventral view. 5. A', aa. abt>rninal tergite VIII. 6, N. wekiuicola, abominal
tergite VIII. 7, N. aa. 8. N. wekiuicola.
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^^ = Nysiusaan. sp.
r~j = Nysius wekiulcolaAshlock& Gagne
Fig. 9. Dislrlbulion ot alpine Nysim species on Hawaii Island. Circle = N. cur. square = A', nckiiiicola.
30 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON
iu Bugs are an interesting insular segre- of what transpired on Mauna Loa several
gate, characterized by restriction to high decades ago, a few specimens of an un-
elevations (Fig. 9), micropterous wings, usual and apparently undescribed Nysius
and a scavenging lifestyle. Nysiiis aa pre- have come to light from baited pitfall
sumably feeds on dead insects that melt traps set in a'a flows near 600 meters el-
out of the margins of retreating snow evation in the Manuka Natural Area Re-
fields on the upper slopes of Mauna Loa serve, on the southwest rift zone of Mau-
during the summer season, a habit docu- na Loa. Although insufficient to allow a
mented for its close relative N. wekiuicola species description, the single female and
on Mauna Kea (Howarth and Montgom- immature so far obtained indicate that the
ery 1980). A seed feeding existence for nearest relatives of the Wekiu Bugs may
N. aa seems unlikely, since the aeolian well be close at hand.
deserts at the elevations it inhabits consist
Acknowledgments
of utterly barren lava flows devoid ofseed
bearing plants that elsewhere constitute This project has built upon years of ef-
the typical food source for the over- fort by many dedicated researchers who
whelming majority of the world's Lygaei- worked in harsh and difficult conditions to
dae (Ashlock and Gagne 1983). obtain specimens and ecological data.
During the Pleistocene the summit of Prime among these are Frank Howarth,
Mauna Kea was glaciated (Porter 1979 a, Bill and Mae Mull, Fred Stone, and Steve
b, c), and given the consequent depression Montgomery, who were the first to bring
of life zones on the mountains during this the remarkable alpine insect communities
period, it is likely that the two currently al- of Mauna Kea to the attention of the sci-
lopatric populations of Wekiu Bugs were entific world. No less important are the
intermingled via a continuous belt of aeo- contributions of the late Wayne Gagne and
lian desert extending across the Humuula his wife Betsy; the former an indefatigable
Saddle. The separation ofN. aa and N. wek- and creative collector who greatly ad-
iuicola on different mountains is thus an vanced our knowledge of Hawaiian Het-
event that is probably no more than 20,000 eroptera, and the latter a tireless champion
years old, and begs the interesting question for the conservation of native Hawaiian
as to whether speciation has proceeded ecosystems and their irreplacable biota.
from a common ancestor within this short This paper is very much a distillation of
time frame. their years of work, and I thank them all
Ashlock and Gagne, in their 1983 pa- very much for openly sharing the results
per, predicted that the closest relative of of their labors.
their N. wekiuicola would be discovered I also thank James Slater, Frank Howarth,
in the Hawaiian islands, and with the dis- and one anonymous reviewer, whose com-
covery and description of N. aa this pre- ments did much to improve the final manu-
diction has indeed been borne out. A more script.
interesting subject for future research,
however, is to locate the closest relatives Literature Cited
of the Wekiu Bugs per se. It seems likely Ashlock. R D. and W. C. Gagne. 1983. A remarkable
that the colonization of the high mountain new micropterous Nysius species from the aeolian
summits on Hawaii was accomplished zone of Mauna Kea, Hawai"i Island (Hemiptera:
from the bottom up, and that putative Heteroptera: Lygaeidae). International Journal of
Wekiu Bug sister groups might be found Entomology 25: 47-55.
in similar aeolian-supplied ecosystems in Howarth. F. G. and S. L. Montgomery. 1980. Noteson
the ecology of the high altitude aeolian zone on
a'a lava flows at lower elevations. Al- Mauna Kea. Elepaio: Journal of the Hawaii Au-
ready, in a scenario strangely reminiscent dobon Society 41: 21-22.
VOLUME NUMBER 31
100. 1
Porter, S. C. 1979a. Qualernary stratigraphy and chro- ogy of Mauna Kea, Hawaii: A 380,000-yr record
nology of Mauna Kea, Hawaii: A .180,000-yrrec- of mid-Pacitic volcanism and ice-cap glacialion.
ord of mid-Pacific volcanism and ice-cap glacia- Geological Society of America Bulletin, pari 2,
tion. Summary. Geological Society of America 90(7): 980-1093.
Bulletin, part 1, 90(7): 609-611. • 1979c. Hawaiian glacial ages. Quaternary Re-
1979b. Quaternary stratigraphy and chronol- search 12: 161-187.
.
