The Plecia of the Pacific and Southeast Asia 
( Bihionidae Diptera ) 1 
D. Elmo Hardy 2 
In the Pacific region the family Bihionidae 
is almost restricted to the southwest portion 
of the hemisphere (Melanesia, Australia, and 
Malaysia) and — except for one species ( Plecia 
palauensis Hardy) from the eastern Caroline 
Islands — the group is completely lacking in 
all of Micronesia and Polynesia. Beyond a line 
drawn north and east of the Philippine Is- 
lands, New Guinea, Solomon Islands, and 
New Caledonia, bibionids become rather 
abundant, especially species of the genus 
'Plecia. The species of the southwest Pacific 
show relationships with those of Indonesia 
and Malaya and southeast Asia. The present 
study includes Ceylon, Burma, Thailand, In- 
dochina, and Malaya as well as the Pacific 
region. Forty-six species and one subspecies 
are now known from this portion of the world. 
I have accumulated these data over a period 
of many years and have studied all of the 
available specimens from these areas. I am 
much indebted to the following entomologists 
for the loan of material from various institu- 
tions: Dr. M. A. Lieftinck and Dr. H. Bosch- 
ma, Rijksmuseum van Natuurlijke Historie, 
Leiden, Holland; Dr. A. M. R. Wegner, 
Museum Zoologicum Bogoriense, Bogor, In- 
donesia; Dr. G. Kruseman, Zoologisch Mu- 
seum, Amsterdam; Paul Freeman, British 
Museum (Natural History), London; Dr. J. L. 
Gressitt, Bernice P. Bishop Museum, Hono- 
lulu, Hawaii; Dr. Alan Stone, U. S. National 
Museum; Dr. Max Beier, Naturhistorisches 
1 Published with the approval of the Director of the 
Hawaii Agricultural Experiment Station as Technical 
Paper No. 386. Manuscript received February 4, 1957. 
2 University of Hawaii, College of Agriculture, Ha- 
waii Agricultural Experiment Station, Honolulu, Hawaii. 
Museum, Wien; and Dr. Delfa Guiglia, 
Museo Civico de Storia Naturale, Genoa. 
key to Plecia of the Pacific region and 
SOUTHEAST ASIA, BASED UPON MALES 
1. Ocelli present, situated on a raised tri- 
angle Plecia (Plecia) 2 
Ocelli and ocellar triangle lacking. Eyes 
of male joined on the front up to the top 
of the vertex. (New Guinea) 
Plecia (Heteroplecia) visenda Hardy 
2. Thorax dark brown to black 3 
Thorax usually predominantly rufous, in 
a few species the mesonotum is discol- 
ored brownish red but the furrows and 
sides are rufous 1 3 
3. Ninth tergum gently concave on hind 
margin, not deft over one-third the 
length of the segment (Fig. 10c) 4 
Ninth tergum deeply cleft, the concavity 
extending nearly to the base of segment 5 
4. Gaspers bilobed, posterior median mar- 
gin of ninth sternum without a sclero- 
tized lobe (Fig. 10a). (Australia). ..... 
erebea Skuse 
Gaspers simple, posterior median mar- 
gin of ninth sternum with a sharp-pointed 
lobe (Fig. 2 6a). ( Java) .tenebrosa n.sp. 
5. Sides of mesonotum and scutellum dull 
red. Mesonotum with three black vittae 
or with front and median portions black 
6 
Thorax entirely black 7 
185 
