A review of the distribution and natural history of Apiocera barri and Nemomydas pantherinus (Diptera: Apioceridae and Mydidae), two rare asiloid flies from the southern Interior of British Columbia

2006·3.8 MB·English

by  Robert A Cannings

J. Entomol. Soc. Brit.Columbia 103,Dhchmbhr2006 55
A review ofthe distribution and natural history
ofApiocera barri and Nemomydaspantherinus
(Diptera: Apioceridae and Mydidae), two rare asiloid flies
from the southern Interior ofBritish Columbia
ROBERT A. CANNINGS^
ABSTRACT
Canada's only apiocerid fly, Apiocera barri Cazier, and sole western mydid fly, Nemo-
mydas pantherinus (Gerstacker), (Diptera: Apioceridae and Mydidae) are rare species
practically restricted to the antelope-brush, Purshia tridentata (Pursh) de Candolle
(Rosaceae), steppe ofthe southern Okanagan Valley ofBritish Columbia. Some aspects
of their natural history are outlined. The distributional records of the species are re-
corded and mapped in the context of antelope-brush steppe in the Okanagan Valley.
This ecosystem has been reduced to one-third of the area occupied in the 1860s. Be-
cause these two flies are conspicuous, rare, and dependent to a large extent on antelope-
brush steppe, they are good candidates for further study in the federal and provincial
efforts to conserve thisthreatenedecosystemandits many rare species.
INTRODUCTION
The families Apioceridae and Mydidae wanian continents (Yeates and Irwin 1996).
are sister clades in the dipteran superfamily The antelope-brush steppe of BC's
Asiloidea (Yeates and Irwin 1996). In west- southern Okanagan Valley (Figs. 1-3) is
em North America, the two families are one of the most endangered ecosystems in
associated with arid or semiarid habitats. Canada and contains many nationally rare
Canada's only apiocerid, Apiocera barri species of plants and animals (Schluter et
Cazier, and sole western mydid, Nemomy- al. 1995). This ecosystem is dominated by
das pantherinus (Gerstacker), (Diptera: the antelope-brush/needle-and-thread grass
Apioceridae and Mydidae) are rare species plant community {Purshia tridentata
practically restricted to the grasslands of (Pursh) de Candolle (Rosaceae) and Hes-
British Columbia (BC) in the southern perostipa comata (Trinius & Ruprecht)
Okanagan Valley. The only other mydid in Barkworth (Poaceae)) (Dyerand Lea 2003).
Canada is Mydas clavatus (Drury), a very Although Purshia is most commonly found
large fly living mostly on beaches of the in this plant community, peripheral commu-
Great Lakes in southern Ontario (Marshall nities, including ponderosa pine woodland,
2006). also may contain this shrub. The antelope-
These two families have similar bio- brush / needle-and-thread grass community
geographical histories. Both ranged widely is red-listed in BC and is globally imperiled
in western and southern Pangaea before its owing to limited world distribution and
breakup in the late Jurassic (180 to 160 substantial decreases in area related to agri-
million years ago) and the distribution of cultural development and urbanization. One
the apiocerids and the plesiomorphic mydid hundred fourrare invertebrates including 33
subfamilies (Raphiomidinae and Megasceli- provincially listed species at risk occur
nae) is congruent with the known geologi- there (Dyer and Lea 2003). Some of these
cal sequence ofthe separation ofthe Gond- species are also listed federally by the fed-
'RoyalBritishColumbiaMuseum, 675 BellevilleStreet, Victoria, BC V8W9W2, [phone],
[email protected]
56 J.Entomol. Soc.Brit.Columbia 103,December2006
Figure 1. Antelope-brush steppe on the east side ofOsoyoos Lake north ofOsoyoos, British
Columbia; view to north. The darker shrubs, especially prevalent in the background, are ante-
lope-brush, Purshia tridentata; the paler ones are big sagebrush, Artemisia tridentata Nuttall
(Asteraceae). Photo: RobertA. Cannings, 1981.
Figure 2. Antelope-brush steppe north of Oliver, British Columbia; view to north. Mclntyre
Bluff, on the left, is near the south end ofVaseux Lake. The pale shrubs in the foreground are
common rabbit-brush, Ericameha nauseosus (Pallas) Nesom & Baird (Asteraceae). Photo:
Stephen R. Cannings, 1979.
J. Entomol. Soc. Brit.Columbia 103,Dhcembhr2006 57
Penticton
Skaha
Lake
Vaseux
Lake
Osoyoos
Lake
Similkameen
River Osoyoos
10 km
Figure 3. Distribution ofApiocera barri(o) andNemomydaspantherinus () in British Colum-
bia. Some symbols represent several records at approximately the same locality. Nemomydas
pantherinus has been collected in two locations outside the range ofthis map: at Vernon to the
north (119°15'N x 50°15'N) and near Grand Forks to the east (49°0rN x 118°32'W). Insert
shows location of the South Okanagan in British Columbia. The original (1860) range of the
antelope-brush / needle-and-thread grass community is shown in grey; the recent distribution
(2001) is inblack.
eral Committee on the Status of Endan- develops lists and status reports of species
gered Wildlife in Canada(COSEWIC). of national relevance and, in conjunction
COSEWIC and the BC Ministry of En- with the BC Invertebrate Recovery Team
vironment's Ecosystems Branch (MOE) are (MOE 2006), adopts recovery plans for
involved in the documentation ofspecies at nationally endangered invertebrate species
risk in BC. The former (COSEWIC 2006) occurring in BC. In addition, the BC Con-
58 J. .. Soc.Brit.Columbia 103,December2006
servation Data Centre (CDC) (MOE 2006) {Litaneutria minor (Scudder)) are obvious
maintains data on species and habitats at choices that are currently being studied.
risk within the province and develops con- Apiocera barri andN.pantherinus are large
servation ranks for them. For the sake of (2 cm long) and conspicuous flies that ap-
practicahty and efficiency, COSEWIC and parently are truly rare and largely restricted
MOE
are focusing attention on a few rare to the threatened antelope-brush steppe
arthropod species in the antelope-brush ecosystem. As such, they are excellent can-
ecosystem that are reasonably well-known didates for official conservation listing. The
andamenable for inventory and otherstudy. information outlinedbelow is the first over-
Behr's hairstreak {Satyriiim behrii (W.H. view ofthe available distributional data on
Edwards)) and the ground mantid, these two species.
MATERIALS AND METHODS
Data were collected from 22 and 18 (UBCZ), and US National Museum of
specimens ofA. barri and A^. pantherinus, Natural History, Washington, DC (USNM).
respectively, from the following institu- In addition, 34 paratypes of A. barri
tions: Canadian National Collection of In- collected at Osoyoos are deposited in a
sects, Agriculture and Agri-food Canada, number of American collections, including
Ottawa, ON (CNCI), Royal British Colum- the American Museum of Natural History
bia Museum, Victoria, BC (flBCM), (New York) and the California Academy of
Spencer Entomological Museum, Univer- Sciences (SanFrancisco) (Cazier 1982).
sity of British Columbia, Vancouver, BC
RESULTS
Apiocera barri barri occurs from the southern Okanagan
Apiocerids, often mistakenly termed Valley in BC south through eastern Wash-
"flower-loving flies" (they seldom visit ington, western Idaho and eastern Oregon
flowers) spend much oftheir time on open to southern Cahfomia (Cazier 1982). In BC
sand or soil in hot, dry areas where they it is most common in the sandy habitat
imbibe water from soil and honeydew from dominated by Purshia on the east side of
beneath aphid-infested plants (Cazier Osoyoos Lake (Fig. 1), but it occurs rarely
1982). Females lay eggs in sandy soil at the at least as far north as the Festuca
base of plants and the larvae apparently (Poaceae) grassland patches growing on
prey on soil invertebrates (McAlpine et al. sandy loam at Penticton. Adults have been
1981). collectedonly from 13 July to 17 August.
Apiocera, the only apiocerid genus, con- Canadian records (Fig. 3): Ohver,
tains 137 described species in four subgen- 13.vii.l923, C.B. Garrett ($, CNCI);
era. Each subgenus is restricted to one of Oliver, 24.vii.1923, E.R. Buckell (S, ?,
four discrete geographical regions: western CNCI); Oliver, 24.vii.1923, P.N. Vroom
North America (including northern Mex- (2(?, (?? in cop., CNCI; ? (RBCM); (?,
ico), southwestern South America, South USNM); Osoyoos, 10.viii.l936, E.R.
Africa, and Australia. This disjunct distri- Buckell ((?? in cop., CNCI, UBCZ);
bution resulted from the break-up of Pan- Osoyoos, 13.viii.l942, E.R. Buckell (4$,
gaea andGondwanaland andthe subsequent CNCI); Osoyoos, Indian desert [east side
displacement of the continental plates Osoyoos Lake], 12.viii.l986, M.J. Sarell
(Yeates and Irwin 1996). The North Ameri- {S, RBCM); same location, 13.viii.l986,
can subgenus, the earliest lineage within the M.J. Sarell ($, R^CM); same location,
genus (Yeates and Irwin 1996), contains 58 17.viii.l986, M.J. Sarell ((?, RBCM);
named species (Cazier 1982). Apiocera Osoyoos Lake, east side, 14.viii.l969,
J. Entomol. Soc. Brit. Columbia 103,December2006 59
J.Bigelow, M. Mortenson and M. Cazier from southern British Columbia south to
{24(S, 10$, paratypes deposited in various California (Stone et al. 1965). In Canada,
US collections [Cazier 1982]); Penticton, this distinctive, yellow and black fly is evi-
West Bench, 3.viii.l986, R.A. Cannings (S, dently restricted to the dry, sandy grass-
RBCM); Vaseux Lake, 7.viii.l978, R.A. lands ofthe southern Okanagan Valley and
Cannings (S, UBCZ). adjacent Boundary region to the east. Most
Nemomydaspantherinus Canadian records are from Oliver and
Adult mydids, with their long antennae Osoyoos in the extreme southern Okanagan
and colourful bodies, are probably wasp where adults have been collected only from
mimics. Adults may be predators but proba- 5 July to 2 August.
bly most feed at flowers and those with Canadian Wrecords (Fig. 3): Grand
atrophied mouthparts (such as Nemomydas) Forks, 5.5km on Hwy 3, 28.vii.1980,
may not feed at all (McAlpine et al. 1981). J.M. Cumming (?, CNCI); OHver,
Little is known about the larvae; some spe- 19.vii.l923, E.R. Buckell ($, CNCI);
cies prey on beetle larvae in rotting wood Oliver, 20.vii.l923, E.R. Buckell ((?,
and sandy soil (McAlpine etal 1981). CNCI); OHver, 24.vii.1923, E.R. Buckell
Mydids are widely distributed, espe- (?, CNCI); Oliver, 22.vii.1923, P.N.
cially in dry tropical, subtropical and Medi- Vroom (2(?, ?, CNCI); Oliver, 24.vii.1923,
terranean climates. The earliest lineages, P.N. Vroom (?, CNCI); Oliver,
Raphiomidinae and Megascelinae, were 20.vii.l953, J.E.H. Martin (?, CNCI);
recently transferred from the Apioceridae to Osoyoos, Haynes Lease Ecological Re-
the Mydidae (Yeates and Irwin 1996). This serve, Throne area [north end Osoyoos
old and widely scattered family contains Lake], 2.viii.l987, S.G. Cannings ((?,
about 355 species in 65 genera worldwide UBCZ); same locality, 27.vii.l988, C.S.
(Dikow 2006). There are 23 genera in the Guppy (3(?, RBCM), G.E. Hutchings (2(?,
New World and at least 54 North American RBCM); same locahty, 8.vii.l979, R.A.
species (B.C. Kondratieff, pers. comm.). Cannings (S. UBCZ); Skaha Lake, Kale-
Nemomydas contains 21 species in North den, 49"25'N X 119°36'W, 25.vii.l997,
and Central America and eastern Asia (B.C. Russell Cannings (S, RBCM); Vernon,
Kondratieff, pers. comm.). 5.vii.l907, E.P. Venables (?, UBCZ).
Nemomydas panthermus is distributed
in intermontane grasslands and dry forests
DISCUSSION
Apiocera barri and A^. panthermus are 10,053 ha were present but by 1938 only
rare in Canada. All but two of the collec- 7,425 ha (74%) remained. Most of this
tion localities for both species are from change was the result offruit tree planting
lowland grasslands in the southern and the growth of towns between about
Okanagan Valley (twoNemomydas records 1900 and 1930. The reduction has contin-
are from just outside that area) - habitats ued at a rate ofabout 2% peryear in recent
that have been frequently examined by times, decreasing from 4,438 ha (44%) in
entomologists for almost a century. The 1995 to 3,386 ha (33%) in 2001 (Dyer and
Canadian ranges of both species are cen- Lea 2003). Figure 3 illustrates the decline
tred on the threatened antelope-brush from I860 to 2001. The latest reductions
steppe ecosystem from Penticton south to are largely related to vineyard expansion.
Osoyoos. Within this ecosystem, the domi- Only 18% of the extant plant community,
nant antelope-brush / needle-and-thread representing 7% ofthe original 1860 area,
grass plant community has declined dra- is protected; 58% is on Indian Reserves
matically. In 1860, about the time of the and 29% is on private lands (Dyer and Lea
first European settlement in the area. 2003). Because of these pressures on the
60 J.Entomol. Soc. Brit.Columbia 103,December2006
extreme northern populations of these tory and for conservation planning by
large and conspicuous flies, the two spe- COSEWIC andMOE.
cies are good candidates for further inven-
ACKNOWLEDGEMENTS
I thank Jeff Gumming (Canadian Na- the original map of Purshia habitat from
tional Collection ofInsects, Agriculture and which Fig. 3 was produced. Boris
Agri-food Canada, Ottawa), Karen Kondratieff (Colorado State University,
Needham (Spencer Entomological Mu- Fort Collins) furnished statistics on the My-
seum, University of BC, Vancouver) and didae and gave permission to use personal
Norman Woodley (US National Museum of communication. I also thank Robb Bennett,
Natural History, Washington) for supplying Art Borkent and an anonymous reviewer
specimens and data. Orville Dyer (BC Min- forvaluable comments on themanuscript.
istry of Environment, Penticton) provided
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