Table Of ContentDAVID K. MCALPINE
AustralianMuseum, Sydney
RELATIONSHIPS OF THE GENUS HETEROCHEILA
(DIPTERA: SCIOMYZOIDEA) WITH DESCRIPTION
OF A NEW FAMILY
McAlpine,D.K., 1991-RelationshipsofthegenusHeterocheila(Diptera:Sciomyzoidea)
withdescriptionofanewfamily.-TijdschriftvoorEntomologie134:193-199-[ISSN0040-
7496]. Published 18December 1991.
A morphological comparison is made of the maritime kelp-living genus Heterocheila
RondaniwiththefamiliesofSciomyzoidea,particularlytheHelcomyzidae.Itisconcluded
that ithas noparticularlycloserelationshipwithanyoneofthesefamilies,andthenew
familyHeterocheilidae (halfbridgeflies) isestablishedforit.Heteromyzaorientalis
Macquart, 1843 is a newsynonymofHeterocheilabuccata (Fallen, 1820).
D. K. McAlpine,AustralianMuseum,BoxA285,SydneySouth2000,Australia.
Keywords. -Diptera; Heterocheilidae, new fam.ily;Holarctic.
InthecourseofmyrecentworkontheCoelopi- Useful descriptive and illustrative material of
dae (kelp flies) (D. McAlpine 1991) it became the adult morphology of Heterocheila has been
apparent that (1) there is disagreement in recent given by Czerny (1930), Hennig (1958), Steyskal
literatureastothefamilypositionofHeterocheila, (1958, 1962, 1987),andGriffiths (1972).Backlund
and (2) it is difficult on morphological grounds to (1945) and Egglishaw (1960b) have described the
justifytheinclusionofHeterocheilainthevarious egg, larva and puparium of Heterocheila, and the
families (Coelopidae, Dryomyzidae, Helcomyzi- latter alsogives importantbiological information.
dae) whereithasbeenrecentlyassigned. Forthese I haveexamineda series ofadultsofbothsexesof
reasons the present investigation was made. H.buccata,andcollectedthespeciesinthefield.W.
TheholarcticgenusnowknownasHeterocheila N. Mathis has provided materialofH. hannai.
Rondani, 1857, has often been referred to by the The family Helcomyzidae is here considered to
synonymous name Oedoparea Loew, 1862. See includeonly thegenera HelcomyzaCurtis,Maori-
both Steyskal (1965), and Gorodkov (1984) for myia Tonnoir & Malloch, and Paractora Bigot. I
complete synonymy. Included species are: (1) H. have given reasons for excluding the group from
buccata (Fallen, 1820) (syn. Heteromyzaorientalis the Dryomyzidae (D. McAlpine 1991) and sug-
Macquart, 1843), from Europe; (2) H. hannai gestedacloserrelationshiptotheCoelopidae.Use-
(Cole, 1921) (syn. H. nudiselaCurran, 1933),from fuldescriptiveandillustrativematerialoftheadult
Pacific North America. Both species live in morphology of Helcomyzidae has been given in
strandedkelp (seeespecially Egglishaw 1960b). most of the papers mentioned above for Hetero-
Heterocheila (or Oedoparea) has often been cheila morphology, also byMalloch (1933). Eggli-
placed in the family Helcomyzidae (e. g. Malloch shaw(1960a)hasdescribedthelarvaandpuparium
1933; Hennig 1937, 1973; Steyskal, 1958, 1965; ofHelcomyza, andgiven biological information. I
Gorodkov 1984), or in the Dryomyzidae, broadly have examined adult material of all genera and
defined to include Helcomyza Curtis and allied mostdescribed species ofHelcomyzidae.
genera (e.g. Czerny 1930; Steyskal 1987;J. McAl- In the following text I use the superfamily Sci-
pine 1989). Egglishaw (1960b), Dobson (1976), omyzoidea to include the families Sciomyzidae,
andGriffiths (1972) havepreferredtoplaceHete- Huttoninidae, Helosciomyzidae, Dryomyzidae,
rocheila in the Coelopidae (with some reserva- Helcomyzidae,Coelopidae,Ropalomeridae,Sepsi-
tions), but I have given definite reasons for its dae, Chamaemyiidae (including Cremifaniidae),
exclusion from the Coelopidae (D. McAlpine Eurychoromyiidae (probably excluding the Gay-
1991), and these need not be repeated here. omyia complex, seeJ. McAlpine 1989), and Laux-
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TijdschriftvoorEntomologie,volume 134, 1991
aniidae(includingCelyphidae).J.McAlpine(1989) tinct from the investigated dryomyzids and the
includesthelastthreefamiliesinaseparatesuper- apparentgroundplan ofCoelopidae. On the other
familyLauxanioidea. hand the number of spermathecae is unrecorded
forthe helcomyzidgenus Paractora.
Increasingknowledgeofspermathecalnumbers
Similarities of Heterocheilato
Helcomyzidae in Schizophorahas demonstratedthat it is a fairly
unstable character. The change from three to two
Heterocheila shares with Helcomyzidae s. str. spermathecae must havehappenedmany times in
thebeachhabitatanddependenceonstrandedkelp, the evolution of the Schizophora, if, in fact, the
utilising it for larval nutrition as well as shelter. changehasalwaysbeenintheonedirection.Inthe
These habits are shared with a number of other Sciomyzoidea, variation in spermathecal number
Diptera, notably the Coelopidae, the sepsidgenus occurs within the families Huttoninidae, Coelopi-
Orygma Meigen, and the sphaerocerid genus (or dae, and Sciomyzidae.
subgenus) ThoracochaetaDuda. Similarityofhab- Other traits shared between Heterocheila and
its andhabitatseems tohavecausedsomeconver- the Helcomyzidae are, so far as I am aware, found
gent similarities among these shoreline flies, so inawidespectrumofsciomyzoidfliesandhavenot
that Orygma and Heterocheila havebeen referred been postulated as evidence ofcloser relationship
to the Coelopidae in thepast. between these two taxa. Such traits include the
InelevatingHelcomyzidaetofamilystatus,Mal- developmentofmollisetae(seeD.McAlpine1991)
loch (1933) emphasised the significance of the onvariouspartsofthemales,thegeneralbrownish
sclerotised precoxal bridge, which connects the greypruinescentcoveringofthecuticle,character-
prosternum to the propleuron on each side. Hen- isticofmany shore-dwelling flies, and the shining
nig (1958) considered this condition to represent parafacial ridges, also found in many flies of mar-
asynapomorphypeculiartotheHelcomyzidaeplus itime or sandy habitats.
Ropalomeridae among theSchizophora, which he
thereforeconsidered toconstitute a monophyletic Differences between Heterocheila and
group. It is now known that prothoracic precoxal Helcomyzidae
bridgesoccurinatleastsomerepresentativesofat
least 19 schizophoran families (Speight 1969, and The principal morphological differences be-
my observations), and many arisals of the condi- tweenadultsofthesetaxaaregivenintable1.They
tionareacknowledged.WithinthesuperfamilySci- are discussed below in numerical sequence, with
omyzoidea,thetraitoccursalsoinsomesciomyzids theadditionofsomecommentsonlarvalmorphol-
as an independent apomorphy. The presence of ogy(18).
precoxal bridges is not now usually considered as 1. Hackman & Väisänen (1985) have investi-
proof for monophyly ofHelcomyzidae and Ropa- gatedthecostalchaetotaxyoftheDiptera (includ-
lomeridae (Griffiths 1972;J. McAlpine 1989),and ing Heterocheila, op. cit.: fig. 16) and assigned it
additional evidence is needed if monophyly of some taxonomievalueat the family andsubfamily
Heterocheila with Helcomyzidae is to be estab- levels. The additional dorsal and ventral rows of
lished.TheprecoxalbridgeinHeterocheiladiffers costalsetulaepresent inHeterocheilaareinagree-
somewhat from that of Helcomyzidae in being mentwithDryomyzidaeandHelosciomyzidae(but
markedly narrower. not Coelopafrigida (Fabricius) with which Hack-
In both Helcomyza and Heterocheila the basal man&Väisänencompareit).Theabsenceofthese
crossvein (crossveinbm-cuorbaseofM3+4accord- series in all generaofHelcomyzidae is incontrast
ing to divergent applications of the Comstock- to the above taxa. The presence of outstanding
Needham notation) lies more obliquely, with ap- anteroventralspinesatintervalsonthemidregion
proach to a longitudinal orientation, than in Dry- of the costa in all Helcomyzidae separates them
omyza. This condition is unlikely to be a ground- sharply from the Dryomyzidae and Heterocheila,
plan condition for Helcomyzidae s. str. in view of and aligns them with Helosciomyzidae and some
thefactthattheundoubtedhelcomyzidMaorimyia Coelopidae (e. g. Lopa convexa McAlpine, Gluma
hasthebasalcrossveinmorenearlytransversethan keyzeriMcAlpine,andRhiswhitleyiMcAlpine,see
infouravailableDryomyzaspecies.Ialsofindsome D. McAlpine 1991).
variation in this character in both Coelopidae and 2. The discontinuity of the parafacial suture on
Sciomyzidae. It appears to be a rather unsatisfac- its lowerpartandpeculiarangularshiningparafa-
tory indicatorofphylogenetic affinities in the Sci- cial ridge are apparently autapomorphies of the
omyzoidea. Helcomyzidae. The condition in Heterocheila is
Heterocheila, Maorimyia, and Helcomyza have probably partly plesiomorphic, though the exten-
two spermathecae in the female abdomen, as dis- sive shining ridge may be an autapomorphy.
194
McAlpine: Heterocheila
3. The incised, vertically orientated postgenal lopidae, andperhaps other families,butexcluding
fold in Heterocheila, is an unusual feature in the Heterocheila, Ropalomeridae, Sepsidae, Chamae-
Sciomyzoideaandpresumablyanautapomorphy.A myiidae, Lauxaniidae and Eurychoromyiidae. Con-
similarconditionoccursintheheleomyzidNephel- vergence in this character cannot beexcluded, but
lum dendrophilum (Malloch) (D. McAlpine 1985: seemslesslikelyforthecomplexDryomyzidaeplus
Fig. 30). Helcomyzidae plus Coelopidae, plus perhaps He-
4. The Helcomyzidae share with the Heloscio- losciomyzidae,asthesefamiliesshowseveralother
myzidae the narrow median emargination of the somewhat inconsistent similarities. Thus, the size
face adapted to receive the prelabrum. The emar- of tergite 6 in Heterocheila makes difficulties for
gination is absent in Heterocheila and Dryomyzi- thehypothesis thatitisclosetotheHelcomyzidae
dae,butasomewhatsimilaremarginationoccursin orCoelopidae.
some,Coelopidae,thoughitisdoubtfulifitisinthe 9.TheaedeagusofHelcomyzidaeismoresimilar
groundplan of the latter. Perhaps the median to that of Dryomyzidae than to that of Hetero-
emargination represents a separate apomorphy in cheila(Griffiths 1972).Mystudyoftheaedeagusin
each group in which itoccurs. Coelopidae(D.McAlpine1991)andHeleomyzidae
5. The shape of the hypopleural channel in the (e. g. D. McAlpine 1967) shows that its structure
Helcomyzidae represents a distinctive autapo- may be quite unstable above the species level.
morphy, absent in Heterocheila (D. McAlpine There are apparently consistent differences in
1991: Fig. 9). both hypandrium and aedeagus between Hetero-
6. The significance of this character has been cheila and Helcomyzidae. The hypandrium of
discussed above under "Similarities'. Heterocheilahastwopairsofprocessesposteriorly
7. The male-restricted apical ventral process of (gonites orparameres) which are absent in helco-
the fore basitarsus is a trait difficult to evaluate myzids.TheaedeagusofHeterocheilahasapairof
phylogenetically,possiblybecauseofirregular loss spreading lateral lobes at the junctionofthe basi-
inanumberoflineages(D.McAlpine 1991).Inthe phallus and distiphallus, which is absent in the
Sciomyzoidea it is apparently restricted to Helco- helcomyzids examined, but it lacks the patch of
myzidae, Coelopidae, and Dryomyzidae, though pubescence near the middle of the length of the
notuniformlypresentinthelastfamily.Itdoesnot distiphallus, which is present in helcomyzids.
appear tobeasynapomorphyas italsooccurs in a Griffiths (1972) hasemphasised thesubstantial
number of Heleomyzoidea and in Heloclusia im- differences in external male genitalia between
perfecta Malloch,a somewhatprimitive represen- Heterocheilaandcertainhelcomyzids.Itispossible
tative of the Nerioidea. This condition seems un- that these structures should be assigned relatively
likely to have originated more than once. I low reliability as indicators of relationship. To
thereforeregarditasaveryancienttraitanditmay judge from my studies of the Heleomyzidae (D.
provideevidenceforrelationshipbetweenSciomy- McAlpine1967,1985)andtheCoelopidae,thecop-
zoidea,Heleomyzoidea,andNerioidea.Inthiscase, ulatory structures are so unstable above species
its absence in Heterocheila would be a derived level that it is difficult to homologise the various
state, but not necessarily a synapomorphy with processes and lobes across the family. Therefore
other sciomyzoids in which it is also absent. there is little logic in inferring autapomorphies
8.Thephylogeneticsignificanceofthereduction betweenspecialconditionsofcertaincoelopidsand
of tergite 6 ofthe male abdomen in Sciomyzoidea thoseoccurringinHeterocheila,which iscertainly
does not appear to have been satisfactorily ex- not so close as a sister group to the Coelopidae.
plained.J. McAlpine (1989) regards reduction of However, I findgreater consistency in hypandrial
tergite 6 as a groundplan apomorphy of his Scio- structurewithinthesmallertaxonomiediversityof
myzoidea (as distinct from Lauxanioidea) but in- the Helcomyzidae.
cludes in Sciomyzoidea such taxa as Heterocheila, 10.Thepresenceofafemale-restrictedenlarged,
Orygma Meigen (Sepsidae), and Rhytidops isolated,posteriorlydirectedbristleoneachlateral
Lindner (Ropalomeridae) whichhavealarge (and marginoftergites 2 to4 andsometimes 5 is char-
in Orygma, according to McAlpine, primarily acteristic for most helcomyzids, including species
J.
unreduced) tergite 6. For this andother reasons, I inall3genera.ItisabsentintheDryomyzidae,but
include the lauxanioid families Chamaemyiidae, thepresenceofsimilarfemale-restrictedbristlesin
Lauxaniidae,andEurychoromyiidaeintheSciomy- two rather plesiomorphic but not closely related
zoidea. coelopidspecies (D. McAlpine 1991) may indicate
If evolutionary change in the size of tergite 6 that it was present in the common ancestor of
takes place only in the direction of reduction, this Helcomyzidae andCoelopidae.
might seem to support the ideaofa monophyletic 11-17. I do not rate these differences in chaeto-
groupincludingDryomyzidae,Helcomyzidae,Coe- taxy very highly, taken individually. Collectively,
195
.
TijdschriftvoorEntomologie,volume 134, 1991
Table 1. DifferencesbetweenHelcomyzidaeandHeterocheila (adults).
Helcomyzidae Heterocheila
1 Midregionofcostawithspacedanteroventralspines, Midregionofcostawithoutanteroventralspines,with
withoutcontinuousseriesofdorsalandventralsetu- regular series of dorsal and ventral (as distinct from
lae. anterodorsalandanteroventral) setulae.
2. Shining parafacial ridge not continued posteriorly Shining parafacial ridge and associated suture con-
below cheek; parafacial suture obsolete or inter- tinuedbelowcheektopostgenalregion.
ruptedbehindangularsectionofridge.
3. Postgenal foldabsent. Postgenalfolddistinctlyincised.
4. Epistomal marginof face with narrow sinuation to Epistomalmarginoffacewithoutnarrowsinuation.
receiveprelabrum.
5. Hypopleural channel rather narrow and parallel- Hypopleuralchannelexpandingrapidlyanteriorly.
sided.
6. Prothoracicprecoxalbridgebroad,wellsclerotised. Prothoracic precoxal bridge narrow, not uniformly
sclerotised.
7. $ fore basitarsus with terminal ventral thumbnail- $ (and 9) fore basitarsus without terminal ventral
likeprocess. process.
8. $abdominaltergite6muchreduced. (5 abdominaltergite6large.
9. Aedeagus with densely pubescent zone or zones, Aedeagus without dense pubescence, with pair of lat-
withoutlaterallobes. erallobes.
10. 9 withonelargebristle neareach lateralmarginon 9 (and$) withoutlateralmarginalbristlesonabdom-
tergites2-4. inaltergites.
11. Generallyonly2 welldeveloped fronto-orbitalbris- Fronto-orbitalbristles 3.
tlespresent.
12. Prostigmatalbristlepresent (sometimesreplacedby Prostigmatalbristleabsent.
severallonghairs).
13. Median series of acrostichal bristles or setulae not Singleregularmedianseriesofshortacrostichalbristles
differentiated. present (inadditiontoprescutellarpair).
14. Prosternumsetulose. Prosternumbare.
15. Metasternumsetulose. Metasternumbare.
16. Abdominalsternite 1 setulose. Abdominalsternite 1 bare.
17. 9 hindtibiawithsubapicalanteriorbristle. 9 (and$) hindtibiawithoutsubapicalanteriorbristle
the seven points indicate a notable degree of div- segments 3 or 4 to 12 (no such spinose creeping
ergencebetween the taxa. weltspresentinHelcomyzaustulata,butthecuticle
18. Larval morphology ofHelcomyzidae is only extensively covered with backwardly directed
recorded for Helcomyza ustulata Curtis, and it is plates), no spine above posterior spiracle (a large
uncertain if this is representative of the family as spine in this position in Helcomyza), each poste-
awhole. However, inviewoftheapparentlyclose rior spiracle with two or three groups of short
relationshipbetween the three helcomyzidgenera hydrofuge hairs (these absent in Helcomyza).
and the very distinctive features of the known There is also difference in the arrangement and
larva,thesemayhavesomesignificanceforhigher spinose armature of the ridges or processes sur-
classification. According to Egglishaw (1960a, rounding the anus, and the position of the anus.
1960b) the third instar larva of Heterocheila buc- EgglishawconsidersthelarvaeofHeterocheilaand
catahascreepingweltsofsmallspinesventrallyon Helcomyza to be so different that they cannot be-
196
McAlpine: Heterocheila
long in the samefamily. I am unable to find in his larger male tergite 6 (see J. McAlpine 1968, for
descriptions and figures any shared distinctive morphologicaldetails). Heterocheila lacks the fol-
traits, which might provide evidence of relatively lowingdistinctivecharactersofEurychoromyiidae:
close relationship between them, though they body form remarkably stout; chaetotaxy greatly
share many points of resemblance to numerous reduced; head structure highly modified; antennal
other schizophoran larvae. segment 1 (scape)elongate;scutellumabbreviated;
mesopleural bristles present; tibiae lacking termi-
Discussion and Conclusion nalspurs;distalsectionofvein7indistinguishable.
There is also considerable difference in the male
The few distinctive points of similarity shared postabdomens and in other characters. Whereas
between Heterocheila and the family Helcomyzi- Heterocheilaisrestrictedtocooltemperateshores,
dae are unconvincing as indicators of close phy- eurychoromyiids are only known from Bolivia, a
logenetic relationship. Each of these traits occurs land-locked tropical country. I conclude that the
elsewhere in the Sciomyzoidea, and the combina- few points ofresemblance between these taxa are
tion or maritime habitat, a shining section of the not indicativeofclose relationship.
parafacial ridge, sclerotised precoxal bridges, and Heterocheila is excluded from the Sciomyzidae
twospermathecaeoccursalsointhegenus Tethina (perhaps including Phaeomyiinae) because of the
Haliday (Chloropoidea: Tethinidae) though this prelabrum,andits larvae feedon neithermolluscs
must beonly remotely relatedtoHelcomyzidae. It nor diplopods. Otherwise there are no special
must be acknowledged that convergence between points of resemblance and no recent author has
HeterocheilaandHelcomyzidaeinthesecharacters suggested aclose relationship.
is not an improbableevent. HeterocheilaisexcludedfromtheHuttoninidae
Ihaveindicatedapossiblesister-grouprelation- (bestregardedasaseparatefamily,notasubfamily
ship between Coelopidae and Helcomyzidae (D. of Sciomyzidae or Helosciomyzidae; further dis-
McAlpine 1991) and this relationshipseems tobe cussed in the forthcoming 2nd edition of'The In-
further supported by costal chaetotaxy. The nu- sects of Australia') because it lacks the following
merous character differences separating Hetero- distinctivefeaturesofHuttoninidae: antennalseg-
cheila and Helcomyzidae indicate a markedevolu- ment 1 without setulae on medial surface; vein 6
tionarydivergence, andcharacters 1,6,7,9and 17 abbreviated;distalsectionofvein7scarcelydistin-
inTable 1 may indicate that Heterocheila is prob- guishable;abdominalsternite1vestigialorabsent;
ably not tobe included in the monophyleticgroup abdominal tergites 1 and2 notpartlyseparatedby
Helcomyzidae plus Coelopidae, oreven the some- a membranous dorsal line. Huttoninids appear to
what less surely foundedgroup Dryomyzidae plus be mainly forest-living and are endemic to New
Helcomyzidaeplus Coelopidae. Zealand.
Heterocheilaresemblesatleastsometaxaofthe Heterocheila is excluded from the Helosciomy-
Ropalomeridae in its sclerotisedprothoracicprec- zidaebecauseitlacksthefollowingapparentlycon-
oxal bridge, large male tergite 6, and two sper- sistent features of that family: costa with promi-
mathecae. These traits, however,do notprovide a nent spaced anteroventral spines; fronto-orbital
strongercase for relationship than those formerly plate with at most two bristles; prothoracic pre-
seen to support the now discarded hypothesis of coxalbridgeabsent;abdominalsternite 1vestigial;
close relationshipbetween Helcomyzidae and Ro- abdominal tergite 6 of male much reduced; each
palomeridae. Heterocheila differs from the Ropa- posterior spiracleoflarva with 4 branched hydro-
lomeridae inter alia in its less markedly divergent fuge hairs (Helosciomyza Hendel and Polytocus
postvertical bristles, differently shaped head cap- Lamb). Helosciomyzids are apparently restricted
sule, unmodified scutellum, absence of setulae on to the south-temperate zone. In my experience
margin of metathoracic spiracle, unmodified theyare found in forests,grasslands, swamp-mar-
femora,anddistinctbutdesclerotiseddistalsection gins,androckyshores,butarenotknowntoinhabit
ofvein7.AlsoHeterocheilalivesonnorth-temper- kelp beds.
ateshore-lines,whiletheropalomeridsare mainly Heterocheila differs from the families Chamae-
inhabitants of tropical forests of the Americas. myiidae (including Cremifaniidae) and Lauxanii-
Most recent workers (e.g.J. McAlpine 1989) con- dae (including Celyphidae) in its complete vein 6
sidertheRopalomeridaetobecloselyrelatedtothe andnumerousothertraits.Thesefamiliesaremor-
Sepsidae.Thereisnoadequatereasonforincluding phologically moreremotefrom Heterocheilathan
Heterocheila in this alliance. are most other sciomyzoids McAlpine 1989),
(J.
Heterocheila also resembles the little known theyarenotassociatedwithkelp,andfurthercom-
neotropical family Eurychoromyiidae in the pro- parison is deemed unnecessary.
thoracicprecoxalbridge,andthelatterhasaneven The exclusion of Heterocheila from all recog-
197
TijdschriftvoorEntomologie,volume 134, 1991
nisedfamiliesofSciomyzoideanecessitatestheset- rite generally understood to be the inverted ster-
tingupofanewmonogenericfamilyofthissuper- nite8); surstylusarticulatedbasally,withbasalan-
family. teriorexpansionorsecondary lobe; cereiseparate;
basiphallus with broadly expanded membranous
Heterocheilidaefam. n. posteriorlobe; distiphallus with complex scleroti-
sation and no pubescence. Female postabdomen
Type genus: Heterocheila Rondani, 1857: 104 (present onlymoderatelyextensile,withallsegmentsshort;
designation). tergites andsternites6-8,epiproct,andhypoproct
Diagnosticdescription all well sclerotisedand setulose; cerei separate,el-
ongate.
Actively flying insects of maritime environ-
ments; habitus and many structural details typical Nomenciatural notes
of Sciomyzoidea; cuticle largely pruinescent and
non-shining; parts of thorax, legs, and abdomen I have examined the holotype of Heteromyza
with mollisetae,particularlydeveloped in male. orientalisMacquart,1843,intheNationalMuseum
Head.- roundedanteriorly; facesomewhatcon- ofNaturalHistory,Paris,andfindittobeidentical
vex centrally, with shallow fovea below each an- withHeterocheilabuccata (Fallen, 1820) (syn.n.).
tenna; parafacial ridge shining, extending, to- ThegiventypelocalityofMacquart'sspecies,Java,
gether with associated suture, below cheek to is erroneous; the species is probably restricted to
postgenal region; cheek deep, setulose; postgenal Europe, where it is apparently absent from
foldlong,distinctlyincised,locatedtowardsposte- warmer,southern areas.
rior surface of head capsule; postvertical bristles I propose the common names half-bridge flies,
oftensubparellel (slightlyvariableinorientation); for representatives of the family Heterocheilidae,
fronto-orbital bristles 3, directed outwards. An- and bridge flies for representatives of the family
tenna, at rest, subporrect; segment 1 with setulae Helcomyzidae. These names refer to thedevelop-
extending on to medial surface; segment 3 ment ofthe prothoracicprecoxalbridge.
rounded-oval; aristawith minutepubescence, seg-
ment5 short, notmuchexserted;prelabrum mod- Acknowledgements
erately developed, narrowly separated from face,
but not fitting into sinuation on lower margin of I am indebted to M. C. D. Speight for help in
latter. finding Heterocheila in the field, to L. Tsacas and
Thorax. - Sternopleural suture not ascending M. Baylac for the opportunity to examine type
posteriorly; hypopleural channel rapidly expand- material in the National Museum ofNatural His-
inganteriorly;marginofmetathoracicspiracleand tory,Paris,andtoW.N.Mathisand R.Vockeroth
J.
sternopleuron bare; prosternum broadly triangu- forstudy material.
lar, with narrowly sclerotised precoxal bridges;
othersignificantcharactersofchaetotaxy andves-
titure as in Table 1. Each tibia with one preapical References
dorsalbristle;allbasitarsiwithoutterminalventral
process; last 2 tarsal segments depressed and dis- Backlund, H. O, 1945. Larvae andpupaeofHeterochila
4st,aelrlibyeeseyxoofpnacdnldoesenedld.yCpolofasctseaudbucsnopbsitrnaouklweeisnt,ahnedxatnaernaedngitunelgraortdosoevrresiiaenls blHKiuuencnlgcgcealrotiam1gy5aFz(a6alF)ly:,susi5ctoougplmrpaa.ptfaairseCkuadrtSwiäisltlhs(kDiatpphtee.t,ssuDiprLpyuoonsmdeydzFiödlararheva)a.ndo--f
eachofdorsal,anteroventral,andventralsetulaeor Czerny,L.,1930.Dryomyzidae.-In:Lindner,E. (editor).
hairs, without spaced anterior or anteroventral Die Fliegen der Paiaearktischen Region 38a: 1-8. E.
spines; vein6 visible approximately to wing mar- Schweizerbart'scheVerlagbuchhandlung,Stuttgart.
gin; vein 7 beyond alula represented by long, Dobson, T, 1976. Chapter 16. Seaweed flies (Diptera:
curvedcrease in membrane. Cinoseelcotpsi:da4e4,7-e4t6c.3).. N-orInt:h-CHhoelnlga,ndL.P(uebdliitsorh)i.ngMaCroimn-e
Abdomen. - Tergites 1 and 2 incompletely se- pany,Amsterdam.
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sternite 1 short,butratherwellsclerotised,bare;7 ustulataCurt.(Dipt.,Dryomyzidae).-Entomologist's
pairs of abdominal spiracles situated in pleural monthlyMagazine96: 39-42.
membrane. Male postabdomen: tergite 6 shorter Egglishaw,H.J.,1960b.StudiesonthefamilyCoelopidae
than preceding tergites but not greatly reduced, (Diptera).-TransactionsoftheRoyalEntomological
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199
