Revision of the New World species of Opacifrons Duda (Diptera, Sphaeroceridae, Limosininae)

27 Pages·1998·21 MB·English

by  S A Marshall

Revision of the New World Species of
Opacifrons Duda (Diptera,
Sphaeroceridae, Limosininae)
S. A. Marshall1’2 and R. Langstaff1
ABSTRACT. The genus Opacifrons Duda is redefined and revised fortheNewWorld. Keys and descrip-
tionsaregivenforthe 17NewWorldOpacifronsspecies,andtheHawaiianspeciesO.aequalis(Grimshaw)
is diagnosed in the key. The phylogeny of the New World, Pacific, and Palaearctic species is discussed.
Leptocera Opacifrons collessi Richards and Leptocera Opacifrons wheeleri Spuler are recognized as
( ) ( )
new synonyms of Opacifrons maculifrons (Becker). Limosina impudica Duda is recognized as a newsyn-
onym of Opacifrons orbicularis (Becker), new combination. Opacifrons bisecta (Malloch), Opacifrons
convexa(Spuler),andOpacifronsorbicularis(Becker)areproposedasnewcombinations,andthefollowing
species are described as new: Opacifrons brevistylus, cubita, distorta, inornata, obunca,pavicula,quadris-
pinosa, quarta, redunca, simplisterna, spatulata, and triloba.
INTRODUCTION ed species from Hawaii, O. aequalis Grimshaw
Opacifrons Duda 1918 is a cosmopolitan genus (1901), form a distinct group of dubious relation-
shipto other Opacifrons. Althoughthemaculifrons
usually associatedwith shoreline debris andsimilar
accumulations of moist detritus. Like many other group is treated here as the sistergroup to thecox-
sphaerocerid flies, they are poorly known and in #ta-clade,theevidenceforthisrelationshipisweak,
need of revision. The genus as currently defined is and most of the similarities between these groups
diagnosed on the basis of a combination of four are plesiomorphies. It is possible that the maculif-
characters: the scutellum has only four marginal rons group will eventually be linked to some other
bristles, there are no presutural dorsocentral bris- sphaerocerid genus, probably of Oriental or Afro-
tles, the midbasitarsus has an enlargedventralbris- tropical affinity. The European species O. digna
tle, and there is no enlarged apicoventral bristle on (Rohacek 1982) probably belongs to the maculif-
the midtibia. NewWorld species ofOpacifronsdif- rons group (see Fig. 101).
fer from the superficially similar genus Pseudocol- In addition to the above species, several other
linella Duda 1924, previously included in Opacif- Palaearctic, Oriental, Afrotropical, and Pacific spe-
rons (see Marshall andSmith 1993), inhavingonly cies might belong in Opacifrons. The Oriental spe-
postsutural dorsocentral bristles and in lacking a cies O. cederholmi Papp 1991, O. niveohaltera
proximal posterodorsal bristle on the midtibia. (Duda 1925), and O. dupliciseta (Duda 1925) and
Most species of Opacifrons belong in a clearly the Afrotropical species O. gbesqueierei Vanschu-
monophyletic group related to the type species [O. ytbroek 1951 and O. rubrifrons (Vanschuytbroek
coxata (Stenhammar 1854)] and here referredtoas 1950) have not been examined in the courseofthis
the coxata-clade. Males in the coxata-clade have work, butatleast O. cederholmiand O. dupliciseta
two prominent, thick bristles arising fromthe mid- probably belong in the maculifrons group. Lepto-
dle of the subanal plate, and females have two cera mirabilis Papp 1973 from Mongolia, treated
broad, flattened apical bristles on each cercus. The as an Opacifrons by Rohacek (1982), does notap-
coxata-clade includes all New World Opacifrons pear to belong in the genus as here defined, but it
except O. maculifrons (Becker 1907) and also in- is left in Opacifrons pending revisionary work on
cludes O. brevisecunda Papp 1991 and O. pseu- the east Palaearctic and Oriental species of the ge-
dimpudica (Deeming 1969) from the Oriental re- nus. The European species O. parvicornis (Duda
gion and O. coxata (Stenhammar), O. moravica 1918) is known only from females, but probably
(Rohacek 1975), and O. elbergi (Papp 1979) from belongs in Opacifrons. The AustralianspeciesLep-
the Palaeartic.
Opacifrons maculifrons and a very closely relat- tocera difficilis Richards 1973 and Leptocera na-
salis (Richards 1973) were originally described in
the subgenus Pseudocollinella which was treated
1. Department ofEnvironmental Biology,Universityof ,
Guelph, Guelph, Ontario, Canada NIG 2W1. as part of Opacifrons from the time Opacifrons
2. Research Associate in Entomology, Natural History was raised to the generic level byPapp (1984) until
Museum of Los Angeles County, 900 Exposition Boule- Pseudocollinella was restituted as a separate genus
vard, Los Angeles, CA 90007. by Marshall and Smith (1993). Both of these Aus-
Contributionsin Science, Number474, pp. 1-27
Natural HistoryMuseum ofLos Angeles County, 1998
)
tralian species are known from females only, and mm; heavily pruinose, body mostly dark brown to
neither belongs in Opacifrons as here defined. black; lower frons usually reddish brown; frons
with a velvety black M-shaped area surrounding
METHODS pruinose areas. Interfrontal bristles in 3-4 small,
Most specimens were preserved in alcohol then dried subequal pairs, upper 2 or 3 pairs usually long. In-
using a critical point drier priorto point-mounting.Since ner orbital bristles well developed, sometimes very
the most useful characters for identification and classifi- large (O. maculifrons group). Eye 2.4-3.4X genal
cation of Opacifrons are characters of the male and fe- height. Postocellar bristles absent (usually) or di-
maleterminalia,wholeabdomenswereroutinelyremoved vergent (O. maculifrons group). Scutum with 2
and cleared in hot lactic acid. Cleared abdomens were large postsutural dorsocentral bristles,eachpreced-
stored inglycerin incapsulespinnedunderthespecimens. ed by 1 or 2 enlarged setulae. Katepisternum with
Morphological terminology essentially follows McAlpine 1-2 minute or small anterodorsal bristles and a
(1981), with some changes following Cumming et al. large posterodorsal bristle usually reaching about
(1995), Wheeler (1995), and Cumming and Sinclair half way to wing base. Midtibia of male with a
i(t1e9p9r6)e.viTohuselytecramllseudbsetpearnnditreia1l0soclfertihteemisalueseadbfdoormtehne,scalenrd- ventral row of short, stout bristles over almost en-
the terminal sternite and tergite of the female abdomen tire length; midtibiaoffemalewithslightlyenlarged
arecalledsternite 10andtergite 10 (Figs. 5 and7) instead preapical bristles only. Dorsal surface of midtibia
ofhypoproct and epiproct as in McAlpine (1981). Cum- with 1 proximal anterodorsal bristle (plus a prox-
mingetal. (1995) andWheeler (1995) usedthetermgon- imal posterodorsal bristle in some Old World spe-
ostylus for the structure referred to in McAlpine (1981) cies of uncertain placement), 1 distal anterodorsal
and most North American sphaerocerid literature as the bristle, 1 distal dorsal bristle, and 2 distal postero-
paramere. The use of the term gonostylus for a structure dorsal bristles (upper one small; absent in O. ma-
previously called a paramere has caused some confusion culifrons group). Midtibia with two anterior bris-
because the term gonostylus has been used by European
sphaerocerid workers to refer to the lateral claspercalled tles distally. First tarsomere of midleg with a stout
the surstylus by most North American workers (as in midventral bristle. Hind tibia usually with a small,
McAlpine 1981). Furthermore, Cumming and Sinclair stout, straight apical ventral bristle; dorsal surface
(1996) argue that the gonostyli sensu Cumming et al. sometimes with a long, thin bristle. Second costal
(1995) are probably not homologous with the gonostyli sector usually 0.8-l.lX third (longer in O. macu-
oflowerDiptera,sowenowfollowCummingandSinclair lifrons group) costa bypassing tip of R4+5 by 1-4
(1996) and Pollet and Cumming (1998) in usingthe neu- vein widths; wing usually lightly infuscated. Halter
tral term postgonite (as in Hennig 1958) for the “para- entirely pale or with knob slightly darkened.
meres” sensu McAlpine (1981).Taxonomicallyimportant Male abdomen. Sternite 5 modified posterome-
structuresofthemaleterminalia,includingthepostgonites
(parameres or gonostyli of previous papers), are labeled dially, usually with a prominent bilobed ortrilobed
in Figure 1. margin. Sternite 6 simple, narrow, and dark. Epan-
Material was examined from the following collections drium uniformly setose. Surstylus small, without
(abbreviationsinparentheses):AmericanMuseumofNat- prominent bristles. Subanal plate broad, each half
uralHistory,NewYork,U.S.A. (AMNH);AustralianNa- usually concave with a very large, stout bristlecen-
tional Insect Collection, Canberra, Australia (ANIC); trally; ventral part bilobed, each lobe weakly
Academy of Natural Sciences, Philadelphia, U.S.A. notchedwith two small apical bristles (stoutbristle
(ANSP); California Academy of Sciences, San Francisco, lost in O. inornata and O. moravica subanalplate
Ub.uSr.gAh.,(UC.ASS.)A;.C(arCnMeNgHie);MuCsaenuamdioafnNaNtautriaolnaHlisCtoolrlye,cPtiitotns,- simple and with only small setae in O,. maculifrons
Ottawa, Canada (CNC); University of Guelph, Guelph, group). Hypandrium complete although weakened
Canada (GUE); Instituto Nacional de Biodiversidad, San medially in most species, without anterior devel-
Jose, Costa Rica (INBIO); Natural History Museum of opment (apodeme absent, as in Fig. 16) except in
LosAngeles County, California,U.S.A. (LACM);Zoolog- O. maculifrons group (Fig. 40); pregonite ^sus-
ical Institute, Lund, Sweden (LUND); Museo Nacional, pensory sclerite, between hypandrium and antero-
Rio de Janeiro, Brazil (MNR); Museo del Instituto de basal lobe ofpostgonite) large,elongate.Postgonite
ZoologiaAgricola,Maracay,Venezuela(MIZA);Museum variable, usually with a prominent posterior lobe
National d’Histoire Naturelle, Paris, France (MNHNP); near base (posterior lobe absent in O. maculifrons
Royal Ontario Museum, Toronto, Canada (ROM); Snow
group). Basiphallus of most species with a very
Entomological Museum, University ofKansas, Lawrence,
U.S.A. (SNOW); Staatliches Museum fiir Naturkunde, large basal opening flanked by two lateral lobes
Ludwigsburg, Germany (SMN);TheNationalMuseumof and sometimes by a single distal lobe; basiphallus
Natural History, Smithsonian Institution, Washington, in O. maculifronsgroupwitha smallbasalopening
D.C., U.S.A. (USNM). and a long, broad, flat epiphallus; distiphallus
broad, setulose, dorsally mostly membranous but
Opacifrons Duda 1918 with 2 weak lateral sclerites, ventrally with a bi-
Limosina {Opacifrons Duda, 1918: 22. Type spe- vleorbseed. sclerite. Subepandrial sclerite simple, trans-
cies Limosina coxata Stenhammar, 1854: 396.
Leptocera Opacifrons Duda Spuler, 1924: 121. Female abdomen. Tergite 8 bare and shining,
( ) , partially or completely divided medially. Tergite 10
Opacifrons Duda, Papp, 1984: 88.
divided longitudinally, each halfusually bare, shin-
GENERIC DESCRIPTION. Length ca. 1.7-2.7 ing, with a small bristle (tergite 10 entire and se-
2 Contributionsin Science, Number474 Marshall and Langstaff: Revision ofOpacifrons
tulose in O. maculifrons group). Cercus usually bergi, although these species come out as a mono-
bare and concave dorsally, apically with 2 flat bris- phyletic group on more than half (12 out of22) of
tles (cercuswithonlythin bristlesin O. maculifrons the equal-length trees. The characters supporting
group). Sternite 8 absent or greatly reduced; ster- the monophyly of this group, especially character
nite 10 well developed. Spermathecae (3) usually 14 (unusually shaped epiphallus) seem to be ofun-
spherical or nearly so, surface smooth or sculp- equivocal interpretation, and a group including
tured, ducts usually short. these four species is recognized here as the coxata-
COMMENTS. With the exception ofthe O. ma- group (Fig. 101). There are several equally sup-
culifrons group, Opacifrons is an extremely uni- ported arrangements of these four species, and al-
formgenus. Chaetotaxyofthe hindtibia, headand though the relationships indicated on Figure 101
halter color, and relative lengths ofthe second and represent only one of the equally parsimonious
third costal sectors are among the fewnongenitalic phylogenies forthegroup,itisthephytogenywhich
characters allowing separation of the species. Sev- seems to be supported by the “best” characters,
eral genitalic characters vary widely between spe- such as the unique male sternite 5 shared by O.
cies. elbergi and O. convexa. The only other significant
SIMILAR GENERA. Opacifrons has been pre- difference between our summary phylogeny (Fig.
viously confused with Pseudocollinella, which dif- 101) and the consensus tree (Fig. 101a), and the
fers in having three dorsocentral bristles, a proxi- only respect in which our summary tree differs
mal posterodorsal midtibial bristle, and a preapical from all of the computer-generated trees, is in the
ventral midtibial bristle. Pseudocollinella is part of placement of O. inornata. All of the minimum-
a monophyletic group including Pbthitia, Racbis- length trees had O. inornata outside the quarta
poda, and Leptocera (Marshall and Smith 1992), group, independently developing the large sternite
and thatgroup is treated here as the sistergroupto 4 (character 8) characteristicofthatgroup.Moving
Opacifrons. Possible synapomorphies between O. inornata into the quarta group (Fig. 101) low-
Opacifrons and the group of genera related to ered the consistency index to 75 and the retention
Pseudocollinellaincludethepresenceofalargeven- index to 89 and replaced the postulatedhomoplasy
tral bristleonthe midbasitarsus (lostinmostPhthi- in sternite 4 with independentloss ofthe large bris-
tia, also present in Chaetopodella), a reduced fe- tles of the subanal plate (character 12) and inde-
male sternite 8, and a strongly developed subanal pendent origin ofa divided female tergite 10 (char-
plate. Generic interrelationships inthe Limosininae acter 24). We prefer the latter, less parsimonious,
have not been adequately assessed, so this sister tree because medial weakening of tergite 10 is a
group relationship is tentative. trivial character, subject to frequent homoplasy
PHYLOGENY AND DISTRIBUTION. A phy- throughout the Sphaeroceridae, and loss of the
logeny for the New World and Pacific Opacifrons large subanal bristles seems to be muchmore likely
was generated using the ie* procedure of the par- than homoplasious development of an enlarged
simony program Hennig86 (Farris 1988) and the male sternite 4 that completely overlaps sternite 5.
character matrix in Table 1. Pseudocollinella and The latter character is unique to Opacifrons,
the related genera Leptocera, Rachispoda, and whereas bristle loss occurs frequently in many lin-
Phthitia (see above) were treated together as the eages. Figure 101 therefore differs from the com-
sistergroup,with boththisgroupofgeneraandthe puter-generated trees in the placement of O. inor-
maculifrons group of Opacifrons considered when nata in the quarta group.
polarizingcharacterswithinthe Opacifronscoxata- Species of the New World Opacifrons fall into
clade. Several characters used to define the coxata- two distinct monophyletic clades (Fig. 101). The
clade, which includes all butone oftheNewWorld maculifrons group includes the cosmopolitan O.
Opacifrons, are unique characters of unequivocal maculifrons and the very closely related Hawaiian
polarity irrespective of outgroup choice. The Pa- O. aequalis. ThePalaearcticspecies O. dignaisalso
laearctic species O. digna, O. coxata, O. moravica, tentatively included in the maculifrons group. The
and O. elbergi were not examined as part of this maculifronsgroup formsthe sistergrouptotherest
study, but were added to the matrix based on pub- of the genus, which is a distinctive and well-sup-
lished descriptions. portedclade includingfourspeciesgroups: thecox-
With the states of character 20 treated as unor- ata, orbicularis, bisecta, and quarta groups.
dered, 22 trees of equal length were generated The coxata group, characterizedprimarilybythe
(length = 37 steps, consistency index = 81, reten- distinctive, epiphallus-bearing basiphallus,includes
tion index = 92); ordering the states of character a single, easily recognized species (O. convexa) in
20 resulted in an identical 22 trees with different the New World and also includes three Palaearctic
statistics (length = 38 steps, consistency index = species (O. moravica, O. elbergi, and O. coxata).
78, retention index = 91). The Nelson consensus The distribution of O. convexa is boreomontane.
tree for both analyses was the same (Fig. 101a). The quarta group is characterized by a strongly
As shown by the Nelson consensus tree (Fig. developed male sternite 4 that overlaps sternite 5.
101a), most ofthe differences between the 22 trees Three of the four species in the group are very
centered around the placement of the four species closely related Neotropical species, but one species
O. convexa, O. coxata, O. moravica, and O. el- (O. inornata from Brazil) is highly autapomorphic,
Contributionsin Science, Number474 Marshall and Langstaff: Revision ofOpacifrons 3
Table 1. Character state distribution for Opacifrons of the Palearctic, Nearctic, Neotropical, and Pacific regions (ex-
cluding species known only from females).
1 11111 11112 22222 22223
12345 67890 12345 67890 12345 67890
Opacifronsmaculifronsgroup
maculifrons (Cosmopolitan) 10110 00000 00001 00000 01000 00001
aequalis (Hawaii) 10110 00000 00001 00000 01000 00001
digna (Palaearctic) 10000 00000 00110 00??0 ????? ??001
Opacifrons coxata group
convexa (Nearctic) 01001 00000 OHIO 00110 10110 00111
coxata (Palaearctic) 01001 00000 01010 00110 10110 00101
moravica (Palaearctic) 01001 00000 00010 00110 10110 00101
elbergi (Palaearctic) 01001 00000 01010 00110 10110 00111
Opacifronsquarta group
inornata (Neotropical) 01001 00100 00000 00100 10100 00101
quarta (Neotropical) 01001 10100 01100 Toiio 10110 01101
simplisterna (Neotropical) 01001 10100 01100 10110 loiro 01101
cubita (Neotropical) 01001 10100 01100 10110 ????? ??101
Opacifrons orbicularisgroup
orbicularis (Neotropical) 01001 00010 01100 00102 10110 10101
spatulata (Neotropical) 01001 00010 01100 01102 10110 10101
distorta (Neotropical) 01001 00011 01100 01102 ????? ??101
redunca (Neotropical) 01001 00011 01100 01102 10110 10101
obunca (Neotropical) 01001 00011 01100 01102 10110 10101
Opacifrons bisecta group
quadrispinosa (Neotropical) 01001 01000 01100 00102 10110 00101
brevistylus (Neotropical) 01001 01000 11100 00102 10110 00101
triloba (Neotropical) 01001 01000 11100 01102 10110 00101
bisecta (NewWorld) 01001 01000 11100 01101 10110 00101
pavicula (Neotropical) 01001 01000 11100 01101 10110 00101
parabisecta (Neotropical) 01001 01000 11100 01101 10110 00101
Excluded species
Opacifronsparvicornis (Duda) Europe, female only; Opacifrons niveohalterata (Duda), Oriental; Opacifrons brevise-
cunda Papp, Oriental; Opacifrons cederholmiPapp, Oriental; Opacifrons dupliciseta (Duda), Oriental; Opacifrons
ghesquiereiVanschuytbroek,Afrotropical; Opacifronsmirabilis (Papp), Mongolia, placement uncertain; Opacifrons
pseudoimpudica (Deeming), Oriental; Opacifrons rubrifrons (Vanschuytbroek), Oriental.
Character list (plesiomorphicstates in brackets)
1. Innerorbital bristles enlarged (innerorbitals minute or absent)
2. Postocellarbristles absent (postocellar bristles present)
3. Head with silverpollinose spots (head withoutpollinose spots)
4. Arista very short (arista much longerthan head)
5. Midtibia with 2 distal anterodorsal bristles (tibia with 1 distal anterodorsal bristle)
6. Hind tibia with a longexserted dorsal bristle (hind tibia with uniformly small bristles)
7. Sternite 5 ofmale prominentposteromediallyand bi- or trilobed (posteromedialpart ofsternite 5 notpromi-
nent)
8. Sternite 4 ofmale greatly expanded, coveringmost ofsternite 5 (sternite4 not expanded over sternite 5)
9. Sternite 5 ofmale notprominentposteromedially but with long posteromediallobes (posteromedialpartofster-
nite 5 without long lobes or with a single longprocess)
10. Longposteromedial lobes ofsternite 5 incurved (posteromedial lobes ofsternite 5 not incurved)
11. Sternite 5 with clear spots (sternite 5 withoutclear spots)
12. Male subanal plate with large spine on each side (subanal plate with onlythin bristles)
13. Postgonitewith prominentposterior lobe (posteriorsurface ofpostgonitewithoutprominentlobe)
14. Basiphalluswith large distal epiphallus (distal part ofbasiphalluswithoutprominentprocess)
15. Basiphalluswith a proximal, dorsoventrallyflattened epiphallus (proximal part ofbasiphalluswithoutprominent
process)
4 Contributionsin Science, Number474 Marshall and Langstaff: Revision of Opacifrons
)
Table 1. Continued.
16. Anteriorlobeofsubanal plate digitate (anteriorlobe ofsubanal plate simple)
17. Lowerposteriorlobe ofsurstylus long (lowerposteriorlobe short)
18. Basiphallusproximallywith 2 lobes flankingopening (basal opening ofbasiphallus not flankedby two lobes)
19. Basiphallus with a distal lobe overbasal opening (basiphallus withoutdistal lobe over opening)
20. Basiphalluswith a quadrate proximalpart and tubulardistal part (0, basiphallus not divided into broadbasal
and narrowdistal parts; 1, tubular distal part weakly developed; 2, tubulardistalpart distinct and elongate)
21. Femaletergite 8 divided (tergite 8 entire)
22. Femaletergite 10 setulose (tergite 10 bare)
23. Femalecerci withbroad, flat apicalbristles (cerci with thinbristles only)
24. Femaletergite 10 divided (tergite 10 entire)
25. Sternite 7 divided or cleft (sternite 7 entire)
26. Spermathecae sculptured (spermathecae smooth)
27. Spermathecalbodies very long (bodies short)
28. Hypandrial apodeme reduced (apodeme long)
29. Sternite 5 ofmale with a single, prominentposteromedialprocess (sternite 5 without a single, long lobe)
30. Females with only small ventralbristles on midtibia (female tibia with enlarged preapical ventralbristle)
1
and its inclusion in this group lowerstheconsisten- 2 Anteriorlobeofmalecercusalmostparallel-sid-
cy index of the cladogram. The rest of the quarta ed, as long as posterior lobe (Fig. 40). Wide-
group includes a Brazilian species (O. cubita a spread .... Opacifrons maculifrons (Becker)
),
species widespread from the Antilles and Central - Anterior lobe of male cercus expanded distally,
America southtoArgentina (O. quarta), anda spe- shorter than posterior lobe (Fig. 46). Hawaii . .
cies ranging from Mexico south to Ecuador (O. Opacifrons aequalis (Grimshaw)
simplisterna). 3 Sternite 5 ofmalewitha single,narrow,strong-
The orbicularis group is an entirely SouthAmer- ly developed posteromedial lobe (Fig. 19). Ter-
icangroupofcloselyrelatedspecies. Opacifronsor- gites 6 and 7 offemale completely divided (Fig.
bicularis, the sister species to the rest ofthe group, 21). Nearctic Opacifrons convexa (Spuler)
is distributed from Argentina north to Venezuela, - Sternite 5 of m.a.le broadly expanded postero-
buttherestofthegroupincludesaBrazilianspecies medially, almost always bilobed (as in Figs. 25,
(O. spatulata and a group of three species from 30). Tergites 6 and 7 of female undivided (Fig.
the Andes.
witThhemobsitsescpteacigersokupnoiwsnlafrrgeolmyCCoesnttaraRlicAamearnidcatnh,e 4 S6)t.erWniitdees4proefadmale strongly modified, overl.ap4-
basal lineages known only from Costa Rica. One ping sternite 5 (Fig. 75). Hindtibiausuallywith
species (O. bisecta) extends from Costa Rica north an exserted dorsal bristle. (quarta group) . . 5
to British Columbia, while the closely related O. - Sternite 4 of male unmodified, not extending
pavicula is described from Argentina. over sternite 5. Hind tibia with only small bris-
tles 8
KEY TO THE 5 Hind tibia with only uniformly small dorsal
NEW WORLD AND PACIFIC SPECIES bristles. Subanal plate with only small bristles.
OF OPACIFRONS Sternite 5 ofmale short, with long, widely sep-
arated posterior lobes (Fig. 35). Legs yellow to
Head with 2 distinct silvery tomentose spots
pale brown. Costa Rica to Brazil
dorsally. Arista very short, less than head Opacifrons inornata, new species
hoeribigthatl. bIrninsetlreso.rbSiutbaalnbarlisptllaesteaolfmomsatleasulnomnogdia-s - Hind tibia with one exserted dorsal bristle
fied, with only small bristles (Fig. 41). Pacific much longer than other tibial bristles. Subanal
and Holarctic. maculifrons group) 2 platewithlargespurs. Sternite5withshortpos-
- Head black wit(h extensive areas of dull polli- teromedial lobes (Fig. 75). Legs usually brown
nosity, dorsally without silvery spots. Arista 6
longer than head height. Inner orbital bristles 6 Posteromedial lobes of male sternite 4 promi-
small, less than half as long as orbital bristles. nent, triangular, andwidely separated (Fig. 75).
Subanal plate with stout spurs as in Figure 3 Exserted bristle of hind tibia strongly devel-
(lost in one Neotropical and one Palaearctic oped, twice as long as tibial width at bristle
species). Widespread, {coxata-clade: most Opa- base. Guatemala to Argentina
cifrons, including the New World species Opacifrons quarta, new species
groups keyed below, and the Old Worldcoxata - Posteromedial lobes ofmale sternite4 rounded;
group) 3 sessile or almost sessile (Fig. 83). Exserted bris-
Contributionsin Science,Number 474 Marshall and Langstaff: Revision of Opacifrons 5
tie of hind tibia weakly developed, less than 13 Subanal plate ofmale with 4 stout bristles (Fig.
1.5X tibial width 7 68). Costa Rica
7 Posteromedial lobes of male sternite 5 sessile, Opacifrons quadrispinosa, new species
separated by less than their widths (Fig. 83). - Subanal plate with 2 stout bristles 14
Surstylus very narrow, not bilobed at posterior 14 Surstylus short, subquadrate, with 2 equally
end. Subanal spurs straight (Fig. 82). Mexico, short lobes posteriorly (Fig. 9). Costa Rica . . .
Costa Rica, Venezuela, and Ecuador Opacifrons brevistylus new species
Opacifrons simplisterna, new species - Surstylus with elongate posteroventral part
- Posteromedial lobes of sternite 5 short but dis- (Fig. 95) 15
tinct, separated by more than width of lobe 15 Posteromediallobesofmalesternite5quadrate,
(Fig. 25). Posterior lobe of surstylus subquad- outer lobes separated by several times their
rate, apically bilobed (Fig. 26). Subanal spurs width, middle lobe strongly deflexed but well
conspicuously bent at middle. Brazil differentiated (Fig. 97). Ecuador
Opacifrons cubita, new species Opacifrons triloba, new species
8 Sternite 5 ofmalewith2 long,widelyseparated - Lobes ofsternite 5 triangular, widthat base not
posteromedial lobes; lobes at leastVa as long as much less than distance between tips of lobes;
sternite (Fig. 54). Sternite 7 of female with a middlelobelesswelldevelopedthanouterlobes
strong posteromedial cleft (Fig. 55) (orbicularis (Fig. 4). Widespread in New World 16
group) 9 16 Posteromedial part of male sternite 5 relatively
- Sternite 5 with entire posteromedial area bulg- narrow and dark, with clearly delineated clear
ing, area usually divided into 2 or 3 lobes each spots and a strong, deflexed middle lobe (Fig.
less than V6 as long as sternite (Fig. 4). Sternite 61). Posterior lobe near postgonite base strong-
7 offemale convex, without large cleft (Fig. 5). ly developed. Costa Rica to Argentina ... 17
(bisecta group) 13 - Posteromedial part of sternite 5 relativelywide
9 Posteromedial lobes of male sternite 5 promi- and pale, with broad, diffuse clear spots and a
nent, dark, narrowly triangular, and directed small, weakly deflexed middle lobe (Fig. 4).
Posterior lobe near postgonite base weakly de-
posteriorly (Fig. 54). Posteroventralpartofsur-
stylusalmostequaltoposterodorsalpartofsur- veloped. British Columbia to Costa Rica ....
Opacifrons bisecta Malloch
stylus (Fig. 52). (Venezuela to Argentina) .... .
17 Posterior lobe near postgonite base elongate
Opacifrons orbicularis (Becker)
- Posteromedial lobes ofsternite 5 quadrate (Fig. and acute. Argentina (Fig. 65)
Opacifrons pavicula, new species
90) or strongly bent or angled medially (Fig.
- Posterior lobe of postgonite base short, quad-
30). Posteroventral part of surstylus narrow,
much longer than posterodorsal part (Fig. 31) rate, and weakly bifid (Fig. 58). Costa Rica . .
Opacifrons parabisecta, new species
10
(Species treatments follow alphabetically.)
10 Posteromedial lobes of male sternite 5 broad
and truncate (Fig. 90). Posterior part ofsursty- SPECIES ACCOUNTS
lus deeply bilobed, with ventral lobe long and
very narrow (Fig. 88). Brazil Opacifrons bisecta (Malloch), new
Opacifrons spatulata, new species combination
- Posteromedial lobes of sternite 5 tapered; bent Figures 1-7
orrecurved medially (Fig. 30). Posteriorpartof
surstylus not deeply bilobed, upper part small Leptocera bisecta Malloch 1914: 20.
11 Leptocera (Limosina) bisecta (Malloch), Richards
11 Posteromedial lobes of male sternite 5 asym- 1967: 13.
metrical, inner part of right lobe deflexed ven- Leptocera (Opacifrons) coxataStenhammar,Spuler
trally (Fig. 30). Argentina 1924: 129 (misidentification).
Opacifrons distorta, new species DESCRIPTION. Lengthca. 2.0-2.5 mm; heavily
- Posteromedial lobes ofmale sternite 5 symmet- pruinose, body mostly dark brown to black; lower
rical 12 irons reddish; face, antennae, and gena dark; leg
12 Posteromedial lobes ofmale sternite 5 medially bases and halter stem pale, at least basal part of
recurved, with apical parts directed anterome- halter knob slightly darkened. Interfrontal bristles
dially (Fig. 80). Eye heightmorethan3.0X gen- in 3-4 small, subequalpairs, middle2pairsslightly
al height. Gena usually luteous or pale brown. longer. Eye 2.5X genal height. Katepisternumwith
Second costal sector 0.8X third. Ecuador . . . . 2 minute anterodorsal bristles and a large postero-
Opacifrons redunca, new species dorsal bristle reaching half way to wing base. Sec-
- Posteromedial lobes of sternite 5 directed me- ond costal sector 0.8X third, wing lightly infuscat-
dially, not recurved (Fig. 49). Eye height less ed.
than 2.8X genal height. Gena dark brown to Male abdomen. Sternite 5 with two posterome-
black. Second andthirdcostal sectorssubequal. dial lobes, area between them forming a postero-
Ecuador .... Opacifrons obunca, new species medial notch aboutas deep as wide, middlepartof
6 Contributionsin Science, Number474 Marshall and Langstaff: Revisionof Opacifrons
/ ./ icv*
^':-A-vv •
5
^ft'lr
Figures 1-7. Opacifrons bisecta. 1. Aedeagus and associated structures (left lateral). 2. Male terminalia (left lateral). 3.
Male terminalia (posterior). 4. Male sternite 5. 5. Female terminalia (ventral). 6. Female terminalia (dorsal). 7. Sperma-
thecae. Abbreviations: sub, subanal plate; lOt, tergite 10; 10s, sternite 10.
notch with a weak, ventrally deflexed lobe. Sursty- Cartago, 12.xii.1909, sweeping over muddy road,
lus triangular in general shape, with an elongate, P.P. Calvert. Other paratypes: COSTA RICA: Car-
acute, posteroventral lobe. Postgonite complex, tago, swept over mud, 10.x and 21.x.1909; 19.ii
with a prominenttransverse ridge onoutersurface, and 3.1.1910, P.P. Calvert (23,4?,ANSP); La Car-
a small posterobasal lobe, and a short, narrowapi- pintera, 4.xii.l909, P.P. Calvert (d,ANSP#6032.4).
cal lobe. Basal part of basiphallus quadrate in lat- OTHER MATERIAL EXAMINED, (ca. 250
eral view, with the upper two faces of the square specimens). (CNC) CANADA: British Columbia.
open and comprising the basal opening, distally UNITED STATES: Arizona, California, NewMex-
with a short neck. ico, Oregon, Texas, Utah, Washington. MEXICO:
Female abdomen. Tergite 6 unmodified. Tergite Morelos, Mexico, Baja California, San Luis Potosi,
7 darkly pigmented, with a small posteromedial Sinalosa, Chiapas. GUATEMALA: San Marcos,
notch. Tergite 8 bare and shining, divided into two San Lorenzo. COSTARICA: Monteverde,Cartago.
dark sclerites, dorsomedial parts tapered. Tergite COMMENTS. Although this species seems im-
10 divided longitudinally, each half bare, shining, possible to distinguish from the partially sympatric
with a long, thin bristle. Cercus bare and concave O. convexa based oncharacters ofthe headortho-
dorsally, apically with 2 flat bristles. Sternite 7 rax, male and female abdominalcharactersareeas-
large, convex posteriorly, with a medial pale area; ily seen and differ widely between these species.
sternite 8 absent; sternite 10 large, bare, trilobed Opacifrons bisecta is even more similar to other
anteriorly. Spermathecae spherical, surfacesmooth, members of the primarily Neotropical O. bisecta
sclerotized parts ofducts slightly shorterthansper- complex, from which it differs most obviously in
mathecal body. surstylus shape and details ofsternite 5 ofthemale.
TYPE MATERIAL. Holotype (<3,ANSP, #6032) Opacifrons bisecta is a western Nearctic-Central
and2paratypes (2$, #s6032.2, .3): COSTARICA: American species that is primarily southwestern in
Contributionsin Science, Number 474 Marshall and Langstaff: Revision ofOpacifrons 7
Figures 8-14. Opacifrons brevistylus. 8.Aedeagusandassociatedstructures (leftlateral). 9.Maleterminalia(leftlateral).
10. Male terminalia (posterior). 11. Male sternites 5-7. 12. Female terminalia (ventral). 13. Female terminalia (dorsal).
14. Spermathecae.
the Nearctic part ofits range. The northernpartof andaverylong,cylindrical,distalneck;distiphallus
its range overlaps that of the boreal and boreo- bulbous, setulose, dorsally mostly membranous,
montane Opacifrons convexa, but it has been in- ventrally with a trilobed sclerite.
frequentlycollectedinthe north. Wehaveseenonly Female abdomen. Tergite 6 unmodified; tergite 7
three Canadian specimens of O. bisecta, one from pale anteromedially and notched posteromedially;
a slash pile on the Queen Charlotte Islands, and tergite 8 shining,completelydivided,withlongthin
two fromthecoastalforestinVancouver(allGUE). ventral arms. Tergite 10 large, with a thin longitu-
dinal pale strip and a thin bristle on each half. Cer-
Opacifrons brevistylus, new species cus short, with 2 pale, flat, subequal apical bristles.
Figures 8-14 Sternite 7 large, dark, with a weak posteromedial
DESCRIPTION. Lengthca. 3.0 mm;heavilypru- notch. Sternite 8 absent or represented by a small
inose, body mostly dark brown to black; lower hyaline sclerite. Sternite 10 bare except atmargins,
frons, gena, face, and first flagellomere reddish with a deep triangular anterior notch. Spermathe-
brown; halter knob grey; stem yellow. Interfrontal cae with reticulate surface and tapered neck, scler-
bristles in 3 small,equalpairs. Eye 3X genalheight. otized parts ofducts as long as spermathecal body.
Katepisternum with a minute anterodorsal setula TYPE MATERIAL. Holotype (d,INBIO) and 14
and a posterodorsal bristle reaching half way to paratypes (10d,4$,CNC,INBIO,GUE): COSTA
wing base. Second costal sector 0.8X third, wing RICA: San Jose: San Gerardo de Dota, 93°3'N,
lightly infuscated. 8°48'W, near trail, 2400-260 m, 8-9.viii.1995,
Male abdomen. Posteromedial part of sternite 5 S.A. Marshall. Other paratypes: COSTA RICA:
trilobate, middle lobe inconspicuous and deflexed SanJose, Rio Humo below Cerro Vueltas, 2850 m,
ventrally. Surstylus subquadrate, shining blackdor- 31.iii.1985, screen sweeps in broadleaf understory
sally and luteous posteroventrally, with a short, in cloud forest, L. Masner, CR-03 (5d,4$,CNC);
sharply tapered posteroventral lobe. Postgonite Cerro de la Muerte, 3200 m, 4.iv.l985, pan traps,
complex,with2posteriorlobesandaparallel-sided H. Goulet, L. Masner (1d,CR-08,CNC); Hwy 2,
apical lobe. Basiphallus with a quadrate basal part km 95, 3200 m, 83°44'W, 9°36'N,CerrodelMuer-
8 Contributionsin Science, Number474 Marshall and Langstaff: Revision of Opacifrons
te, l-7.iii.1985, H. Goulet, L. Masner (ld,CR- 3.vii.l988, sweep near stream and bog, S.A. Mar-
18,CNC); Braulio Carillo National Park, shall (Id,19,GUE); Terrace, 32 mi SW, 6.vi.l960,
ll.iv.1985, 1400-1500m,coolmoistriverbed,sel- J.G. Chillcott (2d,CNC); Aiyansh, Nass R., 500ft,
va premontana screen sweeps, H. Goulet, L. Mas- 25.vi.W1960, G.E. Shewell (19,CNC); SkagitValley,
ner (Id,GUE). 8 mi Hope, 8-28.vii.1980, intercept trap, R.S.
COMMENTS. This species can be separated Anderson (19,GUE); Kamloops, 10 mi N, Mc-
from close relatives by its short surstylus (thus the Queen Lake, 18.vi.1973, H.J. Teskey (ld,CNC);
name brevistylus) and larger average size. The Savona, 19.vii.1988, R. Danielsson (Id,LUND);
deeply incised sternite 10 distinguishes the female Abbotsford, 9.viii.l917,A.L.Melander,“Leptocera
of brevistylus from other members of the group, pusio Zett. det. Spuler” (19,USNM); Yahk,
which have sternite 10 anteriorly trilobed. Mem- 18.vii.1974,P.H. Arnaud,Jr. (Id,CAS);Vancouver,
bers of this complex are very similar in external Stanley Park, ll.vii.1974, P.H. Arnaud, Jr.
characters. (Id,CAS). Manitoba: Ninette, 28.vii.1958, R.L.
Hurley (ld,CNC); Douglas, 2 mi E, 27.vii.1958,
Opacifrons convexa (Spuler), new J.G. Chillcott (19,CNC). Northwest Territories:
combination Frog Creek, Dempster Highway km 594.4, shore,
Figures 15-22 28.vi.1987, S.A. Marshall (Id,GUE). Nova Scotia:
Blomidon, moss in small stream, 27.viii.1989, S.A.
Leptocera (Opacifrons) convexa Spuler, 1924: 130, Marshall (Id,GUE). Ontario: Fergus, 6-9.v.1990,
fig. 9; Richards, 1965: 722. pan trap in floodplain of Grand River, S.A. Mar-
DESCRIPTION. Lengthca. 2.0mm;heavilypru- shall (19,GUE); Arthur, 8 km E, Wylde Lake Bog,
inose, body mostly dark brown to black; lower 30.vi-6.vii.1987, pan trap in floating mat, S.A.
frons and face reddish brown. Halter entirelypale. Marshall (19,GUE); Russel Co., Cumberland,
Interfrontal bristles in 3-4 small pairs, middle vii.1975, Malaise trap, L. Ling (3d,l9,GUE);Mer
pair(s) longest. Eye3X genalheight. Katepisternum Bleue Bog, ll-18.viii.1982, intercept trap, L. Du-
with a minute anterodorsal setula and a postero- mouchel (19,CNC); Gibson Lake, 6 mi E Go
dorsal bristle reaching over halfway to wing base. Home Bay, 6.V.1959,J.G. Chillcott (19,CNC);Ot-
Second costal sector 0.8X third, wing lightlyinfus- tawa, 20.vii.1959,J.R. Vockeroth (19,CNC);Mar-
cated. mora, 10.vii.1952, J.R. Vockeroth (19,CNC); Al-
Male abdomen. Sternite 5 with a prominent,nar- gonquin Park, Lake Sasejewan, 4.vi.l959, B.V. Pe-
row,posteromediallobeprojectingposteroventrally terson (19,CNC). Quebec: Lac Phillipe, 45°37'N,
and tapered and curved apically; sternite withclear 76°W, 30.viii.1959, J.R. Vockeroth (19,CNC);
patches near base of lobe. Surstylus almost trian- Hull, 2.ix.l983, wet flooded forest, L. Dumouchel
gular, projecting dorsally into cleft before subanal (2d,CNC); Saskatchewan: Saskatoon, 28.iv.1926,
plate,witha broad anteriorlobeandataperedpos- K. King (ld,CNC). Yukon Territory: Takhini Hot
teriorlobe endingina broad,flat,pale bristle.Post- Springs, 31.V.1981, L. Vasington and S.G. Can-
gonite with weak posterobasal lobe; apically bent nings (Id,GUE). UNITED STATES: Alaska: Fair-
anteriorly and tapered. Basiphallus with the usual banks, 9.vi.l945, Lienk and Jefferson (ld,CNC);
paired posterodorsal lobes but unlike congeners in Fairbanks, 3.vii.l921, J.M. Aldrich (Id,USNM);
having a long, broad, central lobe (epiphallus) just Big Delta, 5.vi.l951, W.R.M. Mason (4d,19,CNC).
above the short distal neck; distiphallus bulbous, Arizona: Apache Co., Alpine Luna Lake, 9-
setulose, dorsally mostly membranous, ventrally 14.vii.1979, pine meadows, 7900 ft, S. andJ. Peck
with two lateral sclerites. (Id,GUE). California: Nevada Co., Boca Reser-
Female abdomen. Tergite 5 with a conspicuous voir, 7.xii.l986, along spring in mammal run, S.A.
posteromedial pale notch; tergites 6, 7, and 8 com- Marshall (Id,GUE). ColoraWdo: Boulder Co., Mid-
pletely divided dorsally. Tergite 10 longitudinally dle Boulder Creek, 16 km Boulder, Hwy 119,
divided into 2 concave, shining plates, each with 1 2280 m, 8.viii.l973, P.H. Arnaud, Jr. (Id,CAS).
or (rarely) 2 fine bristles. Cerci short, shining, dor- Utah: Summit Co., Henry’s Fork Park, 1-
sally concave, each with 2 large, flat, pale apical 10.viii.1979, 9000 ft, Malaise inmeadowwithwil-
bristles. Sternite 7 unmodified; sternite 8 absent or low, S. and J. Peck (Id,GUE). Washington: Pierce
reduced to a hyaline sclerite; sternite 10 deeply in- Co., Eatonville atJet. 7, 25.vii.1988, P. Danielsson
cisedanteromediallyandpaleposteromedially,thus (19,LUND). Wyoming: Carbon Co., Lake Marie,
W
appearing as two shining, triangular sclerites. 20 km ofCentennial, 3230 m, sweptfromherb-
TYPE MATERIAL. Holotype male: UNITED age near edge of lake, 3230 m, 1.viii.1973, P.H.
STATES: Idaho, Bovill, A.L. Melander (examined, Arnaud, Jr. (Id,CAS).
USNM). Paratypes: UNITED STATES: Washing- COMMENTS. Opacifrons convexa has a dis-
ton: Sultan, l.viii.1917,A.L. Melander(d,USNM); tinctive male sternite 5 dissimilar from other New
Mt. Constitution, 17 and 21.vii, “9”, A.L. Melan- World species but similar to the Palaearctic Opa-
der (2d,USNM); PriestLake, l.viii.1916,A.L.Me- cifrons elbergi (Papp). The basiphallus of O. con-
lander (19,USNM). vexahas anepiphalus unlike otherNewWorldspe-
OTHER MATERIAL EXAMINED. CANADA: cies, butsimilarto that of O. coxata and otherOld
British Columbia: Haney, U.B.C. Research Station, Worldspecies. Opacifronsconvexaand Opacifrons
Contributionsin Science, Number 474 Marshall and Langstaff: Revision of Opacifrons 9
,
Figures 15-22. Opacifronsconvexa. 15.Aedeagusandassociatedstructures(leftlateral). 16.Maleterminalia(leftlateral).
17. Male terminalia (posterior). 18. Male terminalia (ventral). 19. Male sternites 5-7. 20. Female terminalia (ventral).
21. Female terminalia (dorsal). 22. Spermathecae.
elbergi are probably sister species within a species pairs long, almost cruciate. Eye 3.5X genal height.
group also containing the Palaearctic species O. Hind tibia with a thin distal dorsal bristle as long
moravica and O. coxata. as tibial width. Katepisternum with a minute an-
Although O. convexa is easily recognized by terodorsal setula and a small posterodorsal bristle
male or female abdominal characters, based on reaching less than half way to wing base. Second
nonabdominal characters, it is virtually indistin- costal sector 1.1X third, wing lightly infuscated.
guishable from O. bisecta, with which it is sym- Male abdomen. Sternite 4 twice as long as ster-
patric inwesternNorthAmerica. Opacifronsbisec- nite 5,posteromedialpartweaklybilobedandover-
ta is primarily a southwestern species in North lapping sternite 5, lobes dark, setulose, almost ses-
America and Opacifrons convexa is primarily sile, and widely separated; sternite 5 weakly trilo-
transboreal, but the ranges ofthese species overlap bate, middle lobe inconspicuous and deflexed ven-
where O. convexa occurs at high elevations in the trally. Surstylus pale, lobate, slightly tapered, and
southwest, and O. bisecta occurs as far north as bilobate posteriorly. Postgonite with 1 prominent
British Columbia in coastal forests. posterior lobe; distally narrow and tapered. Basi-
Opacifrons cubita new species phallus short, with 3 lobes flanking large basal
opening, no distal neck; distiphallus bulbous, se-
Figures 23-26
tulose, dorsallymostlymembranous,ventrallywith
DESCRIPTION. Lengthca. 2.3 mm;heavilypru- a bilobed sclerite.
inose, body mostly dark brown to black; lower Female unknown.
frons and face reddish brown; first flagellomere TYPE MATERIAL. Holotype (<J,MNR) and 3
black. Interfrontal bristles in 4-5 pairs, upper 3 paratypes (d,GUE): BRAZIL: Rio de Janiero, Ter-
10HContributionsin Science, Number474 Marshall and Langstaff: Revision of Opacifrons