Chalastonepsia orientalis gen. n., sp. n., a second genus in the tribe Metanepsiini (Diptera, Mycetophilidae)

5 Pages·1996·2.8 MB·English

by  G E E Söli

Gi'iR E. E. SOLI
MuseumofZoolog, UniversityofBergen
CHALASTONEPSIA ORIENTALIS GEN. N., SP. N.,
A SECOND GENUS IN THE TRIBE METANEPSIINI
(DIPTERA, MYCETOPHILIDAE)
Soli, G. E. E., 1996. Chalastonepsia orientalis gen. n., sp. n., a second genus in the tribe
Metanepsiini(Diptera,Mycetophilidae).-TijdschriftvoorEntomologie 139:79-83,figs. 1-8.
[ISSN0040-7496]. Published 15October 1996.
Thegenus Chalastonepsiaiserectedforanewspecies from Malaysia, C. orientalis. Thegenus
has numerous characters in common with MetanepsiaEdwards, and the two are likelysister-
groups.ThenewgenusdiffersmostmarkedlyfromMetanepsiainhavingacompleteradialsec-
tor, awelldevelopedSc, andarelativelyshortstemofthemedian fork; further, themaleter-
minaliaareverydifferentinthetwogenera.Awaitingaphylogeneticanalysisofthefamilythe
tribe Metanepsiini is maintained, and an emended diagnosis is given in order to include
Chalastonepsia. The sistergroup ofthe tribe is likely to be found among genera in the tribe
Gnoristini.
GeirE.E.Soli,Presentaddress:ZoologicalMuseum,Sarsgate 1,N-0562 Oslo,Norway.
Keywords.—Mycetophilidae,Metanepsiini,newgenus,newspecies,Malaysia.
The Metanepsiini is usually regarded to represent Diagnostic characters. - Reduced mouthparts,
one offive tribes in the subfamily Sciophilinae in the one-segmented palpus and bead-like flagellum, each
familyMycetophilidae(e.g.Matile 1971,Hutsonetal. flagellomerebulbouswithalongstalk-likeapicalpor-
1980, Vockeroth 1981). Some authors, however, pre- tion, basal partwith numerouslongsetae.
ferto rankthesetribesatthelevelofsubfamilies (e. g. Etymology. - From Greek, chalaston, a chain, re-
Tuomikoski 1966, Hennig 1973, Väisänen 1984, ferring to the outlining ofthe male flagellum, and
1986, Matile 1989). Metanepsiini hitherto includeda Metanepsia, arelatedgenus.
single genus, Metanepsia Edwards, 1927, erected for
theJavanese species, M.javanaEdwards, 1927. Later Description
seven more species were described from the Head. -Antennae inserted below middle ofhead.
Afrotropical region (Matile 1971, 1972, 1975, 1980). Scape and pedicel with numerous small, erect setae.
In the collection ofthe Natural History Museum Fourteen flagellomeres, 1-13 with bulbous basal part
in London a peculiar looking specimen was found with circle ofvery long curved setae and distinctly
among the pinned, unidentified Oriental material of prolonged, stalk-like apical part; last flagellomere
Mycetophilidae. The specimen, a male, had long- conical. Three ocelli, of equal size, situated along
stalked, strongly setose flagellomeres, and reduced straight transverse line. Lateral ocelli well separated
mouthparts. The species must be attributed to the from eye margin. Eyes large, median margin evenly
tribe Metanepsiini, but could not be ascribed to the rounded with very shallow incision above antenna!
genusMetanepsia. socket. Eyes with few small hair-like setae. Back of
head with numerous, evenly dispersed setae.
Postgenaewell developed,with medianconvexitybe-
Methodsandterminology
low occipital foramen. Frons with broad suture be-
Thepinnedspecimenwasclearedandslidemount- tween median ocellus and frontal tubercle. Frontal
edinCanadabalsam. Inaddition,slidemountedma- tubercle distinct, bilobate. Face subquadrate, shorter
terial ofthreeAfrotropical species ofMetanepsiawas than wide, setose. Clypeus rounded, bare. Cibarial
studied.Theterminologyusedinthedescription fol- pumpwell developed. Prementum strongly reduced.
lowsVockeroth (1981) andMcAlpine (1981). Labrumnottraceable. Labellasmall. Stipesweak, ap-
parentlyfused,bare.Laciniaabsent. Palpistronglyre-
Chalastonepsiagen. n. duced, only one visible segment, palpomere 3, with
Type species. - Chalastonepsia orientalissp. n., by some erect setae, and distinct sensory pit, forming a
presentdesignation. hollowdepressiondorsally.
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TijdschriftvoorEntomologie,volume139,1996
Figs. 1-5. Chalastonepsiaorientalisgen.n.,sp.n..—1,head,frontalview;2,flagellomeres7-11;3,wing;4,thorax(outhneof
anepisternumuncertain,seetext); 5,anteroapicaldepressedareaofforetibia.
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SöLl: Chalastonepsiaorientalis
Thorax.-Scutumwith rathershortacrostichaland frons, a costa produced beyond tip ofR,,.,, and the
dorsocentralsetae, andsomewhat longerhiteral setae; tibial setae poorly developed. Chalastonepsia differs
areas in-between bare. Presentai suture distinct. from Metanepsiain havingacomplete radial sector, a
Scutellum with transverse row of small setae. welldevelopedSc, arelativelyshortstemofthemedi-
Antepronotumabouttwiceaslargeasproepisternum, an fork, pointoffurcation ofCuAclosetowingbase,
both setose. Proepimeron large, triangular and bare. gonocoxites fused for most oftheir length, and male
Basisternum with some small setae. Anepisternum tergite9verylargeandcoveringproctiger.
bare. Katepisternum partly covering basal portion of
Chalastonepsiaorientalissp. n.
mid-coxa, bare. Basalarewith large, triangular, interi-
or apodeme. Pleural suture complete, curved. (figs. 1-8)
Anepimeron well sclerotized with distinct cleft dor- Type. - Fiolorype ê: Malaysia, Malay peninsula,
sally. Laterotergite ovate, not protruding, setose. Pahang, Eraser's Hill, 4000 ft., 29.V.1932, H. M.
Mediotergitebare. Metakatepisternumwith somese- Pendlebury (bmnh)
tae.
Wings. - Wing surface on both sides densely Description
clothedwith irregularlyarranged microtrichia. Costa Male(n=1).Totallength2.60mm. Flagellum 1.22
wellproducedbeyondtipofR^,^.Sclong,bare,apical mm,or 1.4timesaslongasscutumandscutellumto-
portion weaker and bent towards R,. Crossvein Sc-r gether.
absent. R, andR^,,withdorsalsetaeonly. Rsdistinct, Coloration. — Unicoloured, yellowish brown,
oblique. Median andcubital forkboth complete, M, wingssomewhatlighter.
falling short ofwing margin. Point of furcation of Head (figs. 1, 2). — Each flagellomere with curved
CuA slightly before crossvein r-m; CuP short and setae longer than entire flagellomere; all trichia and
fold-like. Analveinwell developed. setae situated in small, rounded depressions. Lateral
Legs.—Tibial trichiaallirregularlyarranged. Some ocelli separated from eye margin for distance about
larger apical setae on tibia 1 to 3, and several much 2.1 times, and from median ocellus by about 2.4
smaller setae dispersed along entire length. First tar- times their diameter. Weak, interrupted suture pre-
somere on mid andhind legwith somedistinctsetae sentbetweenlateralocellusandeye. Fronswith 1 seta
onventralhalf. Foretibiawithanteroapicaldepressed in front ofmedian ocellus. Face 0.4 times as long as
areaveryshallow, with someerect trichia. Spurswell broad, with 53 setae. Clypeus ovate, about 0.9 times
developed, shaggy; spur formula 1: 2: 2. Empodium aslongasbroad.
well developed. Tarsal claws with two larger and one Thorax (fig. 4). - Medially divided basisternum
smallerventral tooth. with 5 setae. Scutellum with 14 small setae.
Abdomen. - Segments 1-8 with well developed Laterotergite with 23 setae. Metakatepisternum with
sternitesandtergites,allsetose. Malesegment7and8 4-5 setae.
both reduced, basally narrowed, segment 8 about Wings (fig. 3). -Winglength2.11 mm, measured
twiceas longassegment7. from distal median plate. Length to width 2.1. Sc
Male terminalia (figs. 6-8). -Tergite 9 verylarge, 0.24 times wing length. M-petiole 2.7 times as long
entirely covering gonocoxites dorsally, with numer- asr-m. LengthofM, andM,tothelengthofM-peti-
ousdorsalandventralsetae. Cercilarge,rounded;hy- ole2.94and2.06, respectively.M-basisaboutaslong
poproct well developed. Gonocoxites small, entirely as CuA-petiole. Length of CuA, and CuA, to the
fused ventrally, each with one long gonocoxal length of CuA-petiole 1.67 and 1.11, respectively.
apodeme. Gonostylus small. Aedeagus wide and Analveinwelldeveloped, 1.30 timesas longas CuA-
short. Paramereapparentlyvestigial. petiole.Allbranchesposteriorlyofradiusbare, except
Remarks.-Duetodamagecaused bypinning, the for 0-3 dorsal setae near the wing margin on each of
exact outline ofthe anepisternum, anapleural suture M, andCuA,.
andbasalares remains uncertain. Legs (fig. 5). — Setae on tibiae with weakly devel-
opedalveoli.Anteroapicaldepressedareawith 8 erect
Systematics trichia.Ratiofemurtotibiaforlegs 1 to3:0.98; 1.04;
0.88. Ratio tibia to tarsus forlegs 1 to 3: 1.71; 1.68;
From the number of shared characters with 2.10. Spurlengthsinrelationtotibialdiameter, mea-
Metanepsia, the two genera are likely sistergroups. suredapically: 1.9; 2.1, 2.9; 2.2, 2.7.
Among characters supporting such an arrangement Abdomen.-Abdominalsternites2and3seeming-
arethereducedmouthparts, theone-segmentedpalpi lywithtwo longitudinal foldlines.
and thepoorlydeveloped anteroapical depressedarea Terminalia(figs. 6-8).-Gonocoxitessmall,entire-
oftheforetibia. Inaddition thetwogenerabothhave lyfusedventrally, producedintwoheavilysclerotized
a bilobate and distinct frontal tubercle, a nearly bare median lobes. Dorsal portion ofgonocoxite poorly
TijdschriftvoorEntomologie,volume139,1996
Figs. 6-8. Male terminalia ofChalastonepsia orientalisgen. n., sp. n. - 6, dorsal view, tergite 9 and proctiger removed; 7,
ventralview; 8,tergite9andproctiger(left,ventralview;right,dorsalview).
developed, setose. Two very long gonocoxal Asthenewgenusinvalidatessomeofthelaststate-
apodemes,fusedbytransversebridgewheregonocox- ments,thepossiblerelationshiptotheGnoristiniand
itesmeetdorsally.Gonostylussmall,attachedposteri- Leiini demandsacloserexamination.
orly,bearing2-3smallmediansetae.Aedeagusbroad, Metanepsiaand Chalastonepsiaboth featureseveral
subtriangular. Tergite 9 very large with several erect othercharacters foundamongtheGnoristini, allpre-
setae dorsally, and numerous curved setae ventrally. sent in Palaeodocosia Meunier, 1904 and Syntemna
Proctiger situated ventrobasally of tergite 9 and at- Winnertz, 1863, most of them also in Dziedzickia
tachedtothisbystrongmembranes. Cercusrounded, Johannsen, 1909: anepimeron with a distinct cleft,
with several erect setae apically. Hypoproct more or presence ofone or more erect setae behind basis of
lesstriangularwith2submedian, erectsetae. halter, Sc ending in R, frontal tubercle protruding
and bilobate, scutum with bare stripes, and
metakatepisternum setose. Another character typical
Discussion
forthe Gnoristini is the reduction ofabdominal seg-
Thesystematical positionofthetribeMetanepsiini ments7and8.
in the familyMycetophilidae is uncertain. According Exceptfortheanepimeralcleft, thesecharactersare
to Matile (1971) Metanepsiacan not be ascribed the also present in some genera outside the Gnoristini,
tribe Mycomyini as it does nothave the tibial trichia and thus do not form a basis for any conclusive re-
arrangedindefinitelines;neithercanitbeascribedthe marks. Whenpresentin the Leiini, this often applies
tribe Sciophilini due to the absence ofmacrotrichia to either of the two closely related genera
(orsetae)onthewingmembrane.Thesecharactersare Ectrepesthoneura Enderlein 1911 and Tetragoneura
commonly regarded as good synapomorphies for the Winnertz, 1846. These two genera take a rather iso-
speciesineachofthetwo tribes. Furthermore, Matile lated positionwithin the tribe, and were both tenta-
(1971) rejectstheinclusionofMetanepsiaintheLeiini tivelyincluded in the Gnoristini byVäisänen (1986)
as it lacks an empodium, and has a reduced seventh in hisdelimitation ofthetribe.Anadditionalcharac-
abdominal segment, a long R, and a very short, and ter indicating a possible relationship between
incomplete Rs. Due to theverylongstem ofthe me- Chalastonepsia, Ectrepesthoneura and Tetragoneura is
dianforkandthereducedRs,Matilealsorejectsapos- theabsenceofventralsetaeon theradialveins.
sibleinclusionin theGnoristini. The discrimination between the Gnoristini and
82
SöLl: Chalastonepsiaorientalis
Leiini is still farfrom satisfactory, and the monophy- Thisstudywas fundedbythe Research Council of
ly ofeach ofthe two tribes are highly questionable. Norway (nfr), grant no. 107171/720.
Most likely, the sistergroup ofthe Metanepsiini will
be found among genera included in the Gnoristini, References
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Acknowledgements (Diptera, Mycetophilidae). - Annales zoologici Fennici
MuMseyumbe,stLotnhadnokns,tfoorBrhiisanasPsiitsktiann,ceNdautruirnagl mHiystsotrayy VocF2k.3e:rMoc1tA9h7l,-p2iJ0.n6Re..,et1a9l8.1(.edMsy).ceMtaonphuiallidoafet.hep.N2e2ar3c-t2i4c6.Di-ptIenr:a]..
inApril 1995, andto LoïcMatile, Muséum national Vol. 1.MonographResearchBranchAgricultureCanada.
d'Histoirenaturelle,Paris;TrondAndersen,Museum Ottawa,Ontario.No.27.
of Zoology, Bergen; and to Paul Beuk, Zoölogisch
Museum, Amsterdam, for commenting upon the Received: 24July 1995
manuscript. Accepted: 12 March 1996
83