MOSQUITO
SYSTEMATICS
242
A NEW SUBGENUS
OF CULEX IN THE NEOTROPICAL
(DIPTERA: CULICIDAE)’
VOL.24,
No. 3
REGION
RALPH E. HARBACH AND E. L. PEYTON
Walter Reed BiosystematicsUnit2, Department of Entomology, Walter Reed Army Institute
of Research, Washington,DC 20307-5100
ABSTRACT. Phenacomyia, a new subgenusin the Neotropical Region, is separatedand
distinguishedfrom the subgenusCulex. Additions to published keys are included for its
identif cation among the subgeneraof Culex in the New World.
INTRODUCTION
encesin the adults and pupae, it was obvious
that thesetwo speciesbelong to a phyletic line
The new subgenusdescribedbelow was a distinct from the subgenusCulex Linnaeus.
serendi pitous discovery made during an on- We subsequentlyrecognizedCx. airozai Lane
going project involving the identification of as a member of this group based on adult
mosquitoescollected in Belize. As Louis Pas- characters.In this paper we provide a name
teur once said: “In the fields of observation, for this previously unrecognized subgeneric
chancefavorsthe preparedmind” (translation group, and make a comparison of diagnostic
in Roberts 1989). In this case,while attempt- characterswith the subgenusCulex.
ing to confirm the identification and association of adult specimensand larval exuviae,
Phenacomyia,new subgenus
we noticed that the larva of Culex ( Culex)
lactator Dyar and Knab has an unusual maxType species. Culex corniger Theobald,
illary brush. Under the circumstances, we 1903. Included species:Culex lactator Dyar
probably would have overlooked the signili- and Knab, 1906; Culex airozai Lane, 1945.
cance of this unexpected observation if we
The subgenusPhenacornvia is characterhad not just finished a study of maxillary
ized
by several unique diagnosticand differstructureand its importance in the classificaential
characters.These charactersare listed
tion of the tribe Sabethini. Having learned
and
contrasted
with homologous characters
that overt differences in maxillary structure
of
the
subgenus
Culex in Table 1. The numare generallysupraspecificin nature, we wonbered
characters
in Table 1 correspondto the
dered if Cx. [actator belonged to another
numbered
arrows
in Figs. 1-6. No obvious
subgenus.While trying to answer this quesdistinctions
were
noted
in the cibarial armation, we discovereda number of unique charture
or
genitalia
of
females.
acterswhich distinguishthe larva of this speDiagnosis. Five shared derived characters
cies, and its closely related sisterspecies,Cx.
clearly
indicate the monophyly of this subgecornigerTheobald, from all other subgenera
neric
group
(numbers 4, 5, 11, 16 and 17 in
of Culex. Basedon these striking features, as
the
table
and
figures):setaed-fof gonocoxite
well as correlated though less striking differof male representedby one small hairlike seta,
dorsal arm of phallosomeof male very short,
’ The views of the authors do not purport to reflect the
setae4-7-C of larva inserted in more or less
views of the Department of the Army or the Department
straighttransverseline, siphon of larva with a
of Defense.
prominent
dorsalsetaat midlength, and max’ Reprint requests: Waiter Reed Biosystematics Unit. Muilla
of
larva
with reduced maxillary brush and
seum Support Center, MRC 534, Smithsonian Institution. Washington. DC 20560.
other unique features.
NOVEMBER 1992
Etymology. Phenacomyia is derived from
the Greek nouns phenax (m. deceiver, cheat,
impostor; combining form phenaco-) and
myia (f. fly) in reference to the included specieshaving been mistaken for membersof the
subgenusCulex. The name is feminine in
gender. The three-letter abbreviation Phc. is
recommended for this subgenus.
Discussion. At present, 23 subgenera are
recognized within the genus Culex: the Old
World subgeneraAcalleomyia Leicester,Acallvntrum Stone and Penn, Ajroculex Danilov,
Barraudius Edwards, Culiciornyia Theobald,
Eumelanomyia Theobald, Kitzmilleria Danilov, Lasiosiphon Kirkpatrick, Lophoceraomvia Theobald, and Maillotia Theobald; the
New World subgenera Aedinus Lutz, Allimanta Casaland Garcia, AnoedioporpaDyar,
Belkinomyia Adames and Galindo, Carrollia
Lutz, Melanoconion Theobald, Micraedes
Coquillett, Microculex Theobald, Phenacomyia Harbach and Peyton, and Tinolestes
Coquillett; and the widespreadsubgeneraLutzia Theobald, Neoc&x Dyar, and Culex.
Several of these subgenera,including Culex,
appear to representtwo or more distinct lines
of descent.
The subgenusCzllex is a large and diverse
group with more than 200 specieswhich are
distributed throughout the world. Two main
lines,the Pipiensand Sitiensgroups(Edwards
1932) and two secondaryor annectent lines,
the Atricepsand Duttoni groups(Belkin 1962
and Harbach 1988, respectively), are currently recognizedwithin the subgenus.As far
as known, all New World species of the
subgenusbelong to the Pipiens Group; and
whereasOld World speciesof this group are
classifiedinto a number of subgroups(Mattingly and Rageau 1958, Sirivanakarn 1976,
Harbach 1988) no infrasubgenericgroupsare
currently recognized for New World species
[Lane ( 1953) divided New World speciesinto
Groups A and B based on the absence or
presence,respectively, of a foliform seta (g)
on the gonocoxite of males, but thesegroups
were not recognized by Bram ( 1967a) who
last revisedthe subgenusin the New World].
This is an indication of how little taxonomic
243
work has been done on this subgenusin the
New World, and the results of the present
study clearly demonstratethe need for a thorough revision, with particular emphasis on
charactersof the larval stage.
The affinities of Phenacomyia are unknown. It appearsto be more closelyallied to
the subgenusCulex than to other subgenera
within the genus, and for this reason these
two subgeneraare contrasted in Table 1. It
closely resemblesthe Duttoni Group in the
general ornamentation of adults (Harbach
1988) and the Pipiens Group in the overall
construction of the male genitalia (Belkin
1962, Sirivanakarn 1976, Harbach 1988).
Larvae share the positional relationship of
setae 8,9-C, an antenna of nearly uniform
diameter, and a weakly developed seta 1-A
with Carrollia (Valencia 1973); a well developed seta 7-B with Micraedes (Berlin 1969)
Cx. ( CUX.) duttoni Theobald (Harbach 1988),
and two speciesof Culiciomyia in the Oriental
Region (Bram 1967b); and bear an uncanny
resemblanceto Cx. (Cul. ) cinereusTheobald
of the Ethiopian Region in the development
of the antenna and siphon (Hopkins 1952).
These similarities are probably due to homoplasy since Phenacomyia (New World) and
Culiciomyia (Old World) are otherwise strikingly different in all life stages.
The taxonomy of Cx. corniger and Cx.
lactator was recently reviewed by Strickman
and Pratt (1989) who elevated Cx. lactator
from synonymy with Cx. corniger.These species are closely related and very similar in all
life stages.Strickman and Pratt (1989) should
be consulted for detailed information on the
separationand biology of these species.Lane
(1945, 1953) should be consulted for information regardingCx. airozai.
Phenacomyia is a distinct element of the
genusCulex. It can be distinguishedfrom the
other subgeneraof Culex in the New World
by adding the following modifications to the
keys developed by Berlin and Belkin (1980).
The terms used by Berlin and Belkin for
certain anatomical features have been
changedto conform with the terminology of
Harbach and Knight (1980).
244
VOL. 24, No. 3
MOSQUITO SYSTEMATICS
Table 1. Comparison of diagnostic and differential charactersin the subgeneraPhenacomyia (New
World) and C&x (worldwide).
Stage
Adults
Pupae
Larvae
Character
( 1) scutum
Phenacomyia
Culex
with conspicuous pale-scaled normally unicolorous, some
areas(Fig. lA,C) (see key cou- specieswith varied pale-scaled
areas(Fig. lB,D) (seekey couplet 4a)
plet 4a)
(2) upper mesepimeral absent (Fig. 1C)
present on majority of species
(Fig. ID)
scales
(3) lower mesepimeral l-5 (mode 3) (Fig. 1C)
normally 1,2 (mode 1) (Pipiens
setae
Group) (Fig. 1D), l-3 (Atriceps
Group), l-4 (Duttoni Group),
absent (Sitiens Group)
one small hairlike setacf) (Fig. normally 3,4 setae, all absent
(4) $-setae d-fof
subapical lobe
in a few species,fusually rela2)
tively large (Fig. 3)
(5) $-dorsal arm of
large (Pipiens Group) (Fig. 3)
very short (Fig. 2)
or absent (Atriceps, Duttoni
lateral plate
and Sitiens groups)
(6) $-tergum IX lobe
with 12-29 setae in 3-5 rows, with 2-l 7 setae in l-3 rows,
usually more than 17 setae usually 10 or fewer setae (Fig.
(Fig. 2)
3)
shortand stronglyflared, pinna variable, usually elongate with
(7) trumpet
length less than diameter at pinna equal to or longer than
apex (Fig. 2)
diameter at apex, normally
longer (Fig. 3)
(8) seta 6-I,11
hardly if at all longer than 7- usually distinctly longer than
7-I,11 (Fig. 3)
1,11(Fig. 2)
(9) antenna
short, about 0.35 length of long, about 0.75 length of
head, distal part scarcely if at head, distal part narrower than
all narrower than proximal proximal part (Fig. 5)
part (Fig. 4)
(10) seta 1-A
weakly developed, with few strongly developed, with nushortbranchesinserted at mid- merous long branches, norlength of antenna (Fig. 4)
mally inserted well beyond
midlength of antenna (Fig. 5)
(11) setae4-7-C
insertedin more or lessstraight 4,5,6-C inserted in triangular
line (Fig. 4)
pattern distinctly posterior to
7-C (Fig. 5)
(12) seta 8-C
inserted anterior to 9-C usu- normally inserted posterior to
ally single, longer than 10-C 9-C branched and shorter
(Fig. 4)
than 10-C (Fig. 5)
( 13) setae 14-C
inserted slightly posterior to inserted on line with or slightly
13-C (Fig. 4)
anterior to 13-C (Fig. 5)
(14) seta 3-P
with 3,4 branches,shorterthan single, rarely double, about as
1,2-P (Fig. 4)
long as 1,2-P (Fig. 5)
(15) seta 7-11
as large as 7-I (Fig. 4)
much smaller than 7-I (Fig. 5)
(16) siphon
with a prominent dorsal setaat without dorsal seta at midmidlength (Fig. 4)
length (Fig. 5) (dorsolateral
and lateral setae sometimes
present)
( 17) maxilla
rectangular, maxillary brush ovoid, maxillary brush with
reduced, brush and pilose area long spicules,brush and pilose
on dorsal surface removed la- area borne immediately adjaterad of maxillary suture, setae cent to maxillary suture, setae
4,5-Mx relatively far apart, seta 4,5-Mx closer together, seta lI-Mx inserted about 0.67 from Mx inserted about 0.5 from
base of maxilla (Fig. 6A,B)
baseof maxilla (Fig. 6C,D)
NOVEMBER 1992
245
Fig. 1. A.B, Scutal scalepatternsof (A) Czrl~~_~
(Phucomyiu)
corniger and (B) CZ~/~,X
(Cde,~) psezl~~ostiKrn(ltOSolnu.
C.D. Thoracic pleura of(C) CU/L~(Phcnctcomyia) luctutor and (D) C&X (Cz4kx) psezl~osti~mutosornu. A,C, From
Strickmanand Pratt ( 1989):B,D, from Strickman (1990). Scalesin mm.
ADULTS
4(3).
Pleuron with distinct scalepatcheson
mesokatepisternum
.4a
Pleuron at most with a few scalesalong mesokatepisternalsetae
.5
4a.
Scutum predominately bronzy-brown scaled
with a pattern of white or creamy scalesextending as a lateral band from anterior dorsocentral line to anterior part of supraalararea,
conspicuouslybroader anterolaterally,with a
somewhat inconspicuous narrow extension
246
MOSQUITO SYSTEMATICS
VOL. 24, No. 3
Fig. 2. Male genitaliaand pupa of c‘ll/c)_v
(Hwnacomyia) cornipr (from Strickman and Pratt 1989). Scalesin mm.
247
NOVEMBER 1992
a:
0.2
I
Fig. 3. Male genitalia and pupa of C’lrl~~.~(Czrl~~~)
pipiens(from Harbach 1988). Scales in mm.
NOVEMBER1992
Fig. 5. Larva of Czrkx (Cu/cx)pipiens (from Harbach 1988). Scalesin mm.
249
250
MOSQUITO SYSTEMATICS
VOL. 24, No. 3
T
1
0.1
Fig. 6. Maxillae of (A.B) C’ulev (PIwnmm~Yu) c’omigcr(RDO 133. Dominican Republic. see Belkin and Heinemann
1973:208) and (C.D) C’rr/c~.v(C&x) pipims (from neotype series of Harbach et al. 1985). A.C. Ventral aspects: B-D.
dorsal aspects. Scales in mm,
251
NOVEMBER 1992
dorsally at scutal angle, which often appears as
a small spot at termination, and whitish lines
on each side of precutellar space: without upper mesepimeraland postspiracular scales;
hindtarsomeres with pale bands
Phenacomyiu
Scutum with scales usually unicolorous or with
inconspicuous pale areas. if with an apparent
pattern of lighter scales, then pattern differs
from the above in several respects or species
possessesone or more of the following: upper
mesepimeral scales (sometimes contiguous
with lower mesepimeral scale patch), postspiracular scales. dark hindtarsomeres
Cl&?\-
-
1.
la.
-
1.
la.
-
ACKNOWLEDGMENTS
We are grateful to Richard C. Wilkerson,
Ronald A. Ward, Varuni L. Mallampalli and
JaysonI. Glick for commenting on the manuscript, and to Taina R. Litwak for preparing
the illustrations.
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