A new species of Xylophagus Meigen from Mexico, with a critique of Webb's (1979) phylogeny of the genus (Diptera: Xylophagidae)

6 Pages·1994·1.8 MB·

by  N E Woodley

PROC. ENTOMOL. SOC. WASH.
96(2), 1994, pp. 308-313
A NEW SPECIES OF XYLOPHAGUS MEIGEN FROM MEXICO, WITH A
CRITIQUE OF WEBB'S (1979) PHYLOGENY OF THE GENUS
(DIPTERA: XYLOPHAGIDAE)
Norman Woodley
E.
Systematic Entomology Laboratory, PSI, ARS, USDA, % National Museum ofNatural
NHB
History. 168, Washington, D.C. 20560.
Abstract—Xylophagus durango, new species, is described from Durango, Mexico, the
first report of the genus from south of the United States. Webb's (1979) phylogenetic
treatment ofXylophagus is evaluated.
Key Words: Diptera, Xylophagidae, new species, Mexico, phytogeny
The genus Xylophagus Meigen is known r>\2ignos\?,.—Xylophagus durango differs
from the Palaearctic [13 species(Krivoshei- from other species in the genus in having
naand Mamaev 1988)] and Nearctic [7 spe- an extremely narrow alula, narrower than
cies (Webb 1979)] Regions. A total of 19 the width ofthe base ofvein A,. In Webb's
species is known, with one species, ,\'. cinc- (1979) key it runs to couplet 4, which dif-
tus (De Geer) being Holarctic. The genus ferentiates between X. lugens Loew and X.
hasnotbeen previouslyrecorded from south ductus(DeGeer). Both ofthese specieshave
ofthe United States, with the southernmost predominantly yellow fore coxae, so X. du-
localities being in southern California, Mis- rango can be separated from them imme-
sissippi,andGeorgia(Webb 1979). Thedis- diately because ofits dark front coxae. Ad-
cover>' of the new species described here ditionally, Xylophagusdurangodiffers from
from Durango, Mexico, extends the known X. lugens in having a more slender form,
range ofthe genus southward approximate- the postsutural lateral margins of the scu-
ly 650 miles (about 1050 kilometers). tum tomentose, and the posteriormargin of
the katepistemum and the entire meron to-
Xylophagus durango. New Species mentose. Males of.\'. lugens have more ex-
Type material.—The holotype male, tensive and conspicuous pale yellow col-
housed at the Canadian National Col- oration on the legs and have the frons and
lection. Ottawa, is labeled: "MEXICO: face markedly narrowed from the ocelli to
W
Durango 24 Mi. La Ciudad 7000 feet theoral margin. Xylophagusductusalsohas
12 August 1964 W. R. M. Mason/HOLO- predominantly yellow legs in males, es-
TYPE 5 Xylophagus durango N. E. Wood- pecially the coxae and femora.
ley." The specimen was mounted from al- Description.—.V/a/f.-Colorationblackex-
cohol in July 1991 after hardening in ethyl cept as noted below. Head (Figs. 1-2) with
acetate. It is in excellent condition, missing frontal bare spot and upper face laterally
only the tarsus on the right hind leg. The undertomentumyellowishbrown; fronsand
abdomen beyond the seventh segment is face nearly parallel-sided in anterior view,
maceratedandpreserved inamicrovialwith the inner eye margins converging very
glycerin on the specimen pin. slightlytoward oral margin, frons0.26 width
:
VOLUME NUMBER
96. 2 309
ofhead at anterior ocellus, fronto-facial re- endsyellowish,hindfemuryellowishatbase,
gion at antenna! sockets slightly prominent; grading to brownish near middle becoming
upper frons with pale gray tomentum of darkbrownishapically; frontand mid tibiae
moderate density, ocellar tubercle subshin- narrowly yellowish basally (especially ven-
ing, very thin tomentum present along mar- trally), remainder dark brown, hind tibia
gins of frontal bare spot, dense tomentum yellowish, dorsal surface more brownish,
present around antennal sockets, vaguely apex dark brown; all tarsi with first and sec-
darker lateral to antennae than below, nar- ond segments yellowish, vaguely darkened
rowing ventrally on face toward eye mar- at apices, third segments with basal halves
gins; occiput with gray tomentum ofmod- yellowish, apicallybrownish, fourthand fifth
erate density, with vertex and narrow, tarsomeres dark brownish; legs with uni-
irregulareyemarginsbareandshiny; vertex, formlyshort, inconspicuous, mostlypalepi-
occiput, and genae with whitish pilosity, losity; wing with basal region narrow, alula
longest on genae. a few of the hairs near extremely narrow, linear, narrower than
uppereyemarginsdark;antennaeshort,0.87 width of base of vein A,; wing primarily
length of head, ratio of segments (scape clear, pterostigma dark brown, cell r,
pedicel : [flagellomeres]) 12:5:[7:3:3;3:3;3: brownish beyond origin of vein R^ , ,, and
7], scape with length/width ratio 1.7, sev- slight brownish infuscation present near r-m
enth flagellomere composed of fused 7+8; and base of discal cell; halter with stem
scapeand pedicelwith shortdark hairs; palpi brownish, knob whitish with a brown spot
with ratio of segments 15:17, second seg- nearbaseon ventral side. Abdomen slender,
ment moderately clavate with dark velvety with very narrow lateral and posterior mar-
vestiture, both segments with pale pilosity; ginsoftergitesandposteriormarginsofster-
proboscis brownish yellow. Thorax with nites dirty yellow, tergites with sparse gray-
postpronotallobesandpostalarcalliyellow- ish tomentum dorsally, becomingsomewhat
ish brown, some pleural areas somewhat narrowed posteriorly on tergites 2, 3, and 4
brownish (especially propleuron and anep- so that marginsappearquiteshiny; stemitcs
imeron), katepimeron dull yellowish; scu- primarily without tomentum, but 5, 6, and
tum mostly whitish gray tomentose except 7 with sparse tomentum; entire abdomen
for presutural lateral margins and a narrow with short, sparse yellowish hairs, segment
wedge anterior to scutellum, the tomentum one with longer, more whitish hairs. Male
evenly distributed except slightly denser terminalia with epandrium (Fig. 3) simple,
along two faint discal vittae; scutellum to- posteriormargin evenly rounded, extending
mentose except along margin; pleura to- over posterior segments and most ofcerci;
mentose except for propleuron, anepister- ventralcomponentofhypopygium asin Fig.
num except for extreme ventral margin, 4, similar to other congeners, ejaculatory
anterior two-thirds of katepistemum. and apodeme (endophallus ofWebb 1979) with
mostofanepimeron bareand shiny; scutum anterior margin truncate in dorsal view.
and scutellum with short, inconspicuous Length 9.3 mm.
hairs, mostly pale; tomentose areas ofpleu- Female: Unknown.
ra pale pilose except posterior portion of Etymology.—The specific epithet is a
katepistemum, entire meron, and central noun in apposition, based on the Mexican
portionofmediotergitewithouthairs;coxae state in which the type locality is located.
—
brownish, evenly set with whitish tomen- Remarks. Maleterminaliahavenotbeen
tum, pale pilosity present on anterior sur- utilized extensively in characterizing the
faces, short and sparse on posterior coxa; species ofXylophagus. The differences be-
hind coxa without anterior tubercle; front tween species are subtle compared to those
and mid femora dark brownish, extreme found in manyother Diptera. Hennig(1976:
310 PROCEEDINGS OFTHE ENTOMOLOGICALSOCIETY OF WASHINGTON
^
-^^
,
subs
sps
Figs. 1^. Features of Xylophagiis durango. 1. head of holotype male, left lateral view. 2, anterior view
showingdistributionoftomentum,antennaeremoved. 3,epandriumandproctiger,dorsalview.4,hypopygium,
dorsal view (epandrium and proctiger removed). .Abbreviations; cer. cercus; ea. ejaculatory apodeme; hyp.
hypoproct; sps, sperm sac; subs, subepandrial sclerite.
Figs. 45^6) provided very useful illustra- disticrelationshipsbetween X. durangoand
tions showingthe complex structures ofthe other members of Xylophagus. hoping to
aedeagus and associated parameral sheath utilize the only published phylogeny (Webb
forX. aterMeigen. Thespatialrelationships 1979) as a basis. Webb's work was based
are the same in other species I have ex- primarily on Nearctic species, with only se-
amined. lected Palaearctic species included. I found
I made an attempt to determine the cla- it difficult to score some of the characters
VOLUME NUMBER
96. 2 311
UtilizedbyWebbtoconstructhiscladogram ity decisions. Certainly the Mecoptera are a
in X. durango, especially as all ofthe char- poor choice for this analysis, as this order
acters were not outlined in his list. A cri- may noteven be the sistergroupto the Dip-
tique of his work is provided below, as it tera as a whole (Wood and Borkent 1989).
was found to be inadequate as a basis with Based on the character distributions on
which todeal with additional speciesofA'v- Webb's Fig. 1, 1 put the data in matrix form
lophagiis in a cladistic context. and reanalyzed it using Hennig86 (Farris
Webb (1979) presented a "phylogenetic 1988). No attempt was made to reevaluate
diagram"(1979: Fig. 1)fortheNearcticspe- or otherwise recode the characterdata. The
cies ofXylophagiis as well as 5 Palaearctic tree was rooted by including a hypothetical
species for which he had material. He pro- outgroup taxon with all characters coded as
vided a list of 12 characters with their pro- plesiomorphic. Analysis by the implicit
posedplesiomorphicandapomorphicstates, enumeration algorithm resulted in a single
but the figured tree, which had the apo- tree (Fig. 5). This tree (length = 25, ci = 60,
morphic states indicated at their supposed ri = 79)wasconsiderablydifferentfromthat
origins, contained 15 characters. presented by Webb, which was purported
Upon examination ofall the species seen to be that with "the least number of con-
by Webb, I believe that some ofthe char- vergent origins ofthe apomorphic alterna-
acters he utilized are trivial, particularly tives" (1979: 490). I rearranged the topol-
characters5 (generalpilosityofmesothorax) ogyoftheHennig86treeusingthe DosEquis
and 9 (position ofend ofvein R, at thewing feature of the program to obtain Webb's
margin) which show very little difference tree. This was then diagnosed and found to
between states. I cannot see any difference be 10 steps longer than the actual shortest
between the genae ofmales and females of tree (length = 35, ci = 42, ri = 59). Cleariy,
X. cinctiis. which are coded as different a 10 step difference between these trees in-
(characters 11, 12; I have not seen males of dicates that there are many that are shorter
X. fulgidus Webb, which was coded simi- than that given by Webb. It should be em-
larly). Despite this implied sexual dimor- phasized here that I do not believe either
phism, no mention is made ofthe genae in tree accurately reflects theactual evolution-
the descriptions ofthe females of.\'. cinctus ary history of Xylophagus. but the tree I
and A',fulgidus. For character 3, it appears obtained by Hennig86 analysis is the most
that the polarity ofthe states should be re- parsimonious one based on Webb's char-
versed in Webb's list, since those species acter data.
with a long antennal scape are treated as WebbrecognizedthesubgeneraXylopha-
apomorphic for character 3 on Webb's tree gus sen. str. andArchimyia Enderlein solely
{X. fulgidus. X. ater. X. decorus Williston, on the basis ofthe elongated antennal scape
andX. reflectensWalker). Additionally, this (1979: 498, 512; his character 3). Other re-
character has been miscoded for X. mat- cent authors have discounted the proposed
suniuraiMiyatake on Webb'stree, as it also subgenera (Nagatomi and Saigusa 1969.
has a long antennal scape [it is stated to be Krivosheina and Mamaev 1972, 1988). I
very similarto X. reflectensby Webb(1979: feel that the length ofthe antennal scape is
514); I examined .V. matsumuraito confirm not discretely divisible when all species of
this feature]. Xylophagus are considered. If one accepts
Webb determined his character state po- Webb's character data, but recedes A', mat-
laritiesby "comparingthesituation in more sumuraiashavingalongantennalscape(see
primitive Diptera and Mecoptera" (1979: above), the tree topology in Fig. 5 does not
490). I feel that a more rigorous outgroup change, merely the tree statistics (length =
analysis is required to validate these polar- 26,ci = 57, ri = 78). Thecharacterdiagnosis
312 PROCEEDINGS OFTHE ENTOMOLOGICAL SOCIETY OFWASHINGTON
x<b
<&> J-
sS
.-.^V ;# ^"""^"^ -/r,^^" .<^r,</>
-v^^
/'>%^^.^VV\-^\-^^<^^\e<.^^/
5
10
15
14
3
4
13
2
8
12
1
11
6
7
9
10^ 6^ 12'
15^
14^
'3,4,13^
2.8'
12,10^
'1,11,14,15
7,9.13
10
Fig.5. ShortestcladogramobtainedfromdataofWebb(1979).Opensquaresindicateplesiomorphiccharac"t*e"r
states, closed squares apomorphic states. Superscript "r" indicates reversal back to plesiomorphic state,
indicates independent originsofcharacter states. Character numbersare those used by Webb (1979: Fig. 1).
VOLUME 96, NUMBER 313
ofthis tree indicates that the elongate scape Literature Cited
evolved independently in X. mastumurai Fams, J. A. 1988. Hennig86. Version 1.5. Pon Jef-
and X. decorm + A'. refJectens + A',fulgidus ferson Station, New York.
+ X. ater. Clearly, acceptance ofsubgenera Hennig, W. 1976. Das Hypopygium von Lonchop-
in Xylophagus based on this antennal char- tera lulea Panzer und die phylogenetischen Ver-
acter is unwarranted. On a more pragmatic wtearna)d.tsSctuhtatfgtasrbteerziBeehiutrnaggeenzduerrNCaytcuirokrurnhdacp.haSe(rDieipA-
level, in a genus with such a small number (Biologie) 283: 1-63.
of species that are very similar in general Krivosheina, N. P. and B. M. Mamaev. 1972. Are-
appearance, recognitionofsubgenerawould view ofPalaearctic speciesofthegenus Xylopha-
gus Meig. (Diptera, Xylophagidae). Entomologi-
seem merely to make the generic nomen- cheskoe Obozrenie 51: 430—445 (in Russian).
clature more burdensome. . 1988. Family Xylophagidae, pp. 35-38. In
Soos, A, ed.. Catalogue of Palaearctic Diptera,
Acknowledgments Volume 5, Athericidae-Asilidae. Elsevier, Am-
sterdam, O.xford, New York, Tokyo. 446 pp.
Dr. Jeffrey Gumming provided access to Nagatomi, A. and T. Saigusa. 1969. The Xylophag-
the Malaise trap residues in the Canadian idae ofJapan (Diptera). Memoirs ofthe Faculty
National Collection (CNC), Agriculture Webbo,fADg.nWcu.ltu1r9e7,9.KaAgorsevhiismiaonUonfitvheersNietayrc7t:i1c7s7p-e1c8i8e.s
Canada, Ottawa from which the holotype of Xylophagus (Diptera: .Xylophagidae). Journal
of X. durango was extracted. Gregory W. oftheKansasEntomologicalSociety52:489-523.
Courtney and Wayne N. Mathis of the Wood, D. M. and A. Borkent. 1989. Phylogeny and
Smithsonian Institution, and Manya B. classificationoftheNematocera.Chapter 1 14,pp.
Stoetzel and Allen L. Norrbom ofthe Sys- N1e3a3r3c-t1i3c70D.iptIenraM,cAVlopliunem.eJ.3.F.R,eseed.a.rcMhanBuraalncho,f
tematic Entomology Laboratory, ARS, Agnculture Canada Monograph 32, vi + 1333-
USDA
reviewed the manuscript. 1581 pp.