Larval morphology of Sepsidae

152 Pages·1996·26.5 MB·English

by  Meier, Rudolf

LARVAL MORPHOLOGY OF
THE SEPSIDAE
(DIPTERA: SCIOMYZOIDEA),
WITH A CLADISTIC
ANALYSIS USING
ADULT AND LARVAL CHARACTERS
RUDOLF MEIER
BULLETIN
OF THE
AMERICAN MUSEUM OF NATURAL HISTORY
NUMBER 228 NEW YORK: 1996
Recent issues ofthe Bulletin may be purchased from the Museum. Lists ofback issues ofthe
Bulletin, Novitates, and AnthropologicalPaperspublished during the last five years are available
freeofcharge. Address ordersto: American Museum ofNatural HistoryLibrary, DepartmentD,
Central Park West at 79th St., New York, New York 10024. TEL: [phone]. FAX: (212)
769-5009. E-MAIL: [email protected].
LARVAL MORPHOLOGY OF
THE SEPSIDAE
(DIPTERA: SCIOMYZOIDEA),
WITH A CLADISTIC
ANALYSIS USING
ADULT AND LARVAL CHARACTERS
RUDOLF MEIER
Institutfar Zoologie, Freie Universitdt Berlin,
Konigin-Luise-Stral3e 1-3, 14195 Berlin, Germany
Graduate Training Program in Arthropod Systematics,
Departments ofEntomology,
Cornell University and the American Museum ofNatural History
BULLETIN OF THE AMERICAN MUSEUM OFNATURAL HISTORY
Number 228, 147 pages, 478 figures, 3 tables
Issued January 12, 1996
Price: $12.50 a copy
Copyright C© American Museum ofNaturalHistory 1996 ISSN0003-0090
CONTENTS
Abstract .......................................................... 3
Introduction .......................................................... 3
The Phylogenetic Relationships ofthe Sepsidae ................................ 4
Biology and Natural History ofthe Sepsidae ................................... 5
The Morphology ofSepsid Larvae ............................................ 7
Materials and Methods ........................................................ 8
Acknowledgments ......................................................... 9
Descriptions 9
..................................................................
Description ofSepsid Larvae ............ 10
.....................................
Key to Sepsid Genera ....................................................... 12
1. Genus Australosepsis Malloch, 1925 ........... ............................ 14
2. Genus Decachaetophora Duda, 1926 ...................................... 16
3. Genus Dicranosepsis Duda, 1926 .......................................... 18
4. Genus Lasionemopoda Duda, 1926 ....................................... 20
5. Genus Meroplius Rondani, 1874 .......................................... 22
6. Genus Nemopoda Robineau-Desvoidy, 1830 ............................... 27
7. Genus Ortalischema Frey, 1925 ........................................... 33
8. Genus Orygma Meigen, 1830 ............................................. 35
9. Genus Palaeosepsis Duda, 1925 ........................................... 37
10. Genus Parapalaeosepsis Duda, 1926 ...................................... 45
11. Genus Paratoxopoda Duda, 1926 ......................................... 49
12. Genus Saltella Robineau-Desvoidy, 1830 .................................. 51
13. Genus Sepsis Fallen ............... 57
......................................
14. Genus Susanomira Pont, 1987 ........................................... 102
15. Genus Themira Robineau-Desvoidy, 1830 ................................. 104
16. Genus Xenosepsis Malloch, 1925 ......................................... 123
Cladistic Analysis . 127
............................................................
Characters for Cladistic Analysis ............................................. 127
Results 134
..........................................................
Discussion 135
.....
Conflict Between Larval and Adult Data .................................. 139
Comparison with Traditional Classifications .................................. 140
References 142
...................................................................
2
In contrast to their disgusting habitat the species are really beautiful little
insects and with their curious habit of pirouetting about with extended
vibratingwings they attract attention by their dainty dance.
-Melander and Spuler(1917: 11) on sepsids
ABSTRACT
A phylogenetic hypothesis based on larval and sis. The history of sepsid classification is briefly
adultcharactersisproposedfortheSepsidae. The discussed, and the most influential systems are
cladistic analysis employed 85 characters and 57 comparedwiththeresultsofthecladisticanalysis.
taxa and found 16 equally parsimonious clado- The phylogenetic relationships ofthe genera for
grams. The strict consensus tree and a'preferred which the larvae are unknown are inferred from
treeare presented, the region ofthetreeinwhich adultcharacters.
the parsimonious cladograms differ is indicated, Larvae for the following genera are described
andthecompetingarrangementsoftaxaareshown. based on a comprehensive scanning electron mi-
Outgroup representatives included two species of croscopical study: Australosepsis (1 sp.), Deca-
ropalomerids (Ropalomera sp., Willistoniella chaetophora (1 sp.), Dicranosepsis (1 sp.), Lasi-
pleuropunctata),twospeciesofcoelopids(Coelopa onemopoda(1 sp.),Meroplius(2 spp.),Nemopoda
frigida, Chaetocoelopa sydneyensis), andone spe- (3 spp.), Ortalischema (1 sp.), Orygma(1 sp.),Pa-
cies ofdryomyzid (Neuroctena caucasica). Based laeosepsis(4 spp.),Parapalaeosepsis(2spp.),Par-
onlarvalcharacters, theCoelopidae are the sister atoxopoda(1 sp.),Saltella(3spp.),Sepsis(20spp.),
groupoftheSepsidae.Basedonboththeadultand Susanomira (1 sp.), Themira (10 spp.), and Xe-
thecombineddatasets,theRopalomeridae,which nosepsis. Except fortwo species ofNemopodafor
are generally regarded as the sister group ofthe which the cephalic region could not be studied,
Sepsidae, areconfirmedastheirclosestlivingrel- drawings ofthe following structures are supplied:
atives. Two new morphological autapormorphies cephalicregion(ventralandlateral),maxillarypalp,
relatedtotheposterior spiraclesaredescribed for anterior spiracle, ventral creeping welt, last seg-
the Sepsidae. The followingphylogenetichypoth- ment (ventral, lateral, and dorsal), and spiracular
esis is proposed based on the combined data set: plate ofthe posteriorspiracle. Keysarepresented
(Orygma (Ortalischema (Paratoxopoda (Themira thatallowtheidentificationofallgeneraandmost
(Decachaetophora ((Saltella Susanomira) (Nem- species withinthegenera. However, the morpho-
opoda (Lasionemopoda ((Meroplius Xenosepsis) logical differences between some species within
(Palaeosepsis(Palaeosepsis(Parapalaeosepsis(Di- SepsisandThemiraaresosubtlethatspeciesiden-
cranosepsis (Sepsis (Australosepsis Sepsis)). The tifications are difficult or even impossible. The
genus Xenosepsis is synonymized with Meroplius literatureonlarval morphology, biology, anddis-
(syn.nov.),andthegenusAustralosepsiswithSep- tribution ofthe species is briefly summarized.
INTRODUCTION
Dipterists with an interest in the phylo- about the biology ofthe species and its var-
genetic relationships ofhigher flies (Cyclor- ious semaphoronts can be gained. I am con-
rhapha)havetraditionallydevotedlittletime vincedthatdevelopingculturetechniquesfor
to the study of immatures (but see Okada, species with saprophagous larvae will fre-
1968; O'Hara, 1989). In partthis was due to quentlybeeasyandtheresultswilljustifythe
the difficulty of obtaining immature stages. efforts (e.g., see publications on sciomyzid
Evenlargeinsectcollectionshousefewlarvae biology and additional publications by B. A.
and systematic collecting ofeggs and larvae Foote as listed in Ferrar, 1987).
hasbeen largely neglected. Undoubtedly, ac- Larvalcharactershavebeen crucial forthe
quiring larvae can be quite labor intensive reconstruction of the higher-level relation-
becauseitisgenerally difficulttoidentifyim- ships in the Diptera. In the third volume of
matures to species without establishing cul- the "Manual of the Nearctic Flies" on the
tures. However, as soon as rearing methods phylogenetic relationships ofthe Diptera, 60
aredeveloped, muchinteresting information of84 characters for the Nematocera and 20
3
4 BULLETINAMERICAN MUSEUM OFNATURAL HISTORY NO. 228
of 60 for the "orthorrhaphous" Brachycera atleast 13acceptedgeneraincludefewerthan
came from immatures (Wood and Borkent, four species each. In some cases, Hennig
1989; Woodley, 1989). However, the pro- (1949) already recognized that some ofthe
portion of larval characters in the Cyclor- genera couldbe synonymizedbuthis sugges-
rhaphachapterwasconsiderablylower. Iam tions, often not convincingly supported by
convinced that some ofthe uncertainty over characters, have beenlargelyneglectedinthe
the phylogenetic position of some families literature. One goal ofmy study was to elu-
and superfamilies in the Cyclorrhapha could cidate which ofthe small genera have to be
be resolved by larval characters, although maintained due to their special position in
Ferrar (1987) was more pessimistic after a the phylogenetic system ofthe Sepsidae and
study ofthe published literature: "I still be- which can be safely synonymized.
lieve that to some extent one can draw con- The early classificatory history ofthe Sep-
clusions on such [phylogenetic] relationship sidae is summarized by Duda (1925, 1926).
from immature stages, but I now consider ItwasthroughhisandMelanderandSpuler's
that larval morphology is predominantly (1917) contributions that the Sepsidae and
functional andthat larvae show a number of Piophilidaewererecognizedasdifferentfam-
interesting examples of parallel evolution." ilies and that misplaced genera were re-
(Ferrar, 1987). Theconflictingpointsofview moved. Hennig (1937) completed this task
arepartlyduetoadifferentkindofstudythat when he added Orygma luctuosum, which
Ferrar and I are referring to. Traditionally, had been incorrectly classified in the Coelo-
only a small number of characters like the pidae, to the Sepsidae.
arrangement of spiracle openings, general WithintheSciomyzoidea, theSepsidaeand
body shape or the cephalopharyngeal skele- Ropalomeridae are considered sistergroups.
ton were studied. Thelatterevenbecame the According to McAlpine (1989), this sister-
embodiment ofpapers onthemorphology of group relationship is based on eight syna-
"maggots." Therewasoftenratherlittlevari- pomorphies. However, McAlpine deter-
ation in these character systems. Phyloge- minedthecharacterpolaritieswithrespectto
neticanalysesmustbebasedonconsiderably the groundpattem of the Sciomyzoidea (al-
morecharacters, whichinthecaseoftheSep- though it is uncertain whetherthe superfam-
sidae involves the ultrastructure of the ce- ily is monophyletic). Some ofthe characters
phalicregion andthe anal segment. Both can occur not only in the Sepsidae and the Ro-
only be adequately explored with the aid of palomeridaebutalsoinotherfamilieswithin
scanning electron microscopy (Grodowitz et the "superfamily." When all the characters
al., 1982; Colwell and Kokko, 1986; Ferrar, forwhichthisisthecaseareeliminated, only
1987; Ruiz-Martinez etal., 1989, 1990). Un- fourunambiguous synapomorphies support-
fortunately, the use ofSEM for the study of ing the sister-group relationship between the
immature Cyclorrhapha is in its infancy and Ropalomeridae andthe Sepsidae remain: (1)
cladistic evaluation ofthe morphological in- One or more subvibrissal setae tend to be
formationisexceedinglyrare(butseeO'Hara, enlarged and vibrissa-like. This is certainly
1989). Most SEM studies are exclusively de- not a convincing character since the subvi-
scriptive and involve only one or a few se- brissae are often enlarged in other acalyp-
lected species. trates and the character may even be contin-
uousuponcloserinspectionofmanytaxa. (2)
Vein A2 is absent. Again, this in itselfwould
THE PHYLOGENETIC
notconstitutegoodevidencesincelossofthis
RELATIONSHIPS OF THE SEPSIDAE
veinhasoccurredmanytimesindependently
The Sepsidae are a small family ofacalyp- within the Acalyptrates. (3) Aedeagal apo-
tratefliesintheSciomyzoidea(Hennig, 1971, demeisfusedtohypandrium,i.e.,cuneiform.
1973; McAlpine, 1989). The classification of Unfortunately the apodeme has only been
thefamilyischaracterizedbyalarge number studied for a few species (the ropalomerid
of very small genera. Sepsis and Themira Rhytidopsfloridensisandthesepsids Orygma
comprise far more than halfofthe 240 de- luctuosum, Themira putris, Nemopoda niti-
scribedspecies(Pont, 1979).Atthesametime, dula,Sepsisvicaria). Itmayconstituteanim-
1996 MEIER: LARVAL MORPHOLOGY OF SEPSIDAE 5
portantsynapomorphy.(4)Posteriorthoracic these relationship hypotheses are mainly
spiracle has one or more distinct setae on convincingbased onthe comparatively large
posterior margin. This last character is cer- number ofcharacters supporting them.
tainlythestrongestsynapomorphyforthesis- Threedifferentclassificationschemeshave
ter-grouprelationshipbetweentheRopalom- beenproposedfortheSepsidae.Theyaredis-
eridae and Sepsidae. It is unique within the cussed in more detail in Meier (submitted)
Sciomyzoidea and very rare within the re- andsummarizedintable 1.ExceptforDuda's
mainingCyclorrhapha(italsooccursinsome (1925) proposal the systems were used to
Muscidae and possibly some Oestroidea; classify the species of individual biogeo-
Pont, in litt.). In 1973, Hennig argued that graphic regions, and it is difficult to infer
the Eurychoromyiidae have a similar seta, where the authors would have placed other
but since the seta ofEurychoromyia is well genera not occurring in that region. Duda's
posterior to the margin ofthe metathoracic (1925)andZuska's(1980)system, latermod-
spiracle, theEurychoromyiidae arenolonger ified by Steyskal (1987), were probably in-
included in the Sciomyzoidea. tended to reflect only loosely phylogenetic
The monophyly ofthe Sepsidae has never relationships. Only Hennig's classification
been seriously questioned (Hennig, 1973; (1949) is explicitly phylogenetic. However,
Griffiths, 1972; McAlpine, 1989). Griffiths at the time he prepared the manuscript he
(1972) mentioned six autapomorphies. The hadnotyetdevelopedhisphylogeneticmeth-
palpiarereduced, the6thand7thabdominal od (Richter and Meier, 1994), and some of
spiracles of the female lie within their re- the proposed monophyletic groups are not
spective tergites (Hennig, 1958), the surstyli supportedbyanyapomorphyfoundthrough-
are fused with the epandrium, the 6th ab- out the genera composing the taxon (see
dominal spiracle ofthe male lies within the Meier, submitted, for a detailed discussion).
6th tergite, the 7th sternite ofthe male is not Also, some of his species groups are obvi-
delimited (either lost or fused with 8th ster- ously supported by plesiomorphies since he
nite), andtheanal (Al)veinis shortened, not uses both the absence ofa structure as well
reachingthewingmargin(Hennig, 1958;Grif- as its presence to support different taxa (lack
fiths, 1972; McAlpine, 1989). McAlpine ofosmeteria and tufts on the fourth sternites
(1989)addedaprominent medianfacialkeel to support the Sepsis-, and presence ofthese
as a 7th autapomorphy. Some ofthese char- structures to support the Themira group).
acters probably do not constitute valid au-
tapomorphies for the family. For example,
BIOLOGY AND NATURAL HISTORY
the fusion ofthe surstyli to the epandrium is
OF THE SEPSIDAE
restrictedamongthebasalsepsidstoOrygma
andtheToxopodini. Mostotherbasalsepsids Formanyyears,thebiologyoftheSepsidae
stillhavefreesurstylisothatfusionhasprob- has received little attention, and Melander
ablyoccurredseveraltimesindependentlyand and Spuler (1917) observed: "Possibly be-
may not furnish support for the monophyly cause ofthecommonness andthe familiarity
of the Sepsidae. Also, the palpi of Orygma ofthe species, possiblybecause oftheirfilthy
are not smaller than those of the Ropalo- habits, the group has never been adequately
meridae, so that minute palpi probably studied." Common, theyareindeed. Thelar-
evolved within the Sepsidae anddo notcon- vae and adults ofthis group are exclusively
stitute an autapomorphy for the family (for saprophagous with most species living on
a more detailed discussion, see Meier, sub- mammal feces (Hafez, 1939, 1947, 1948;
mitted). Hammer, 1941). Cow dung is the preferred
Neithertheapomorphiesmentionedforthe substrateofthe mostabundant speciesin the
Sepsidae nor most of those supporting the Sepsisgroupandinthegenus Saltella (Ham-
sister-group relationship of the Sepsidae to mer, 1941; Mohr, 1943; Pont, 1979). Many
the Ropalomeridae are particularly convinc- species of the Themira group also live on
ing.Mostalsooccurinotherpresumablymore decayingplant matter, carcasses, sludge, and
distantly related "Acalyptrates" and the fungi (Hennig, 1949). Little is known about
charactersappearpronetohomoplasy. Thus, theecology ofspecies ofthe Toxopodagroup
6 BULLETIN AMERICAN MUSEUM OFNATURAL HISTORY NO. 228
TABLE 1
Comparison ofThreePreviousClassificationsoftheSepsidae
DUDA1925 HENNIG1949,1965 ZUSKA1977,1980;
STEYSKAL,1987
Orygmawasnotyet Orygmaluctuosumassister Orygmanotincluded****
includedinthefamily groupofremainingsepsids
Saltellinae*: Saltellinae:
Saltella*, SaltellainThemiragroup Saltella
Australosepsis* Australosepsisclassifiedin Australosepsis in
Sepsisgroup theSepsinae
Toxopodinae: Toxopodagroup: Toxopodinae:
Toxopoda, Toxopoda, Toxopoda,
Paratoxopoda, Paratoxopoda**, Paratoxopoda,
Platytoxopoda** Platytoxopoda** Platytoxopoda
Themirinae: Themiragroup: Sepsinae:
Saltella,
Ortalischema*, Ortalischema, Ortalischema**,
Themira(Enicita, Themira, Themira**,
Enicomira, Susanomira**, Susanomira**,
Cheligaster) Zuskamira** Zuskamira**
Meropliinae:
Decachaetophora, Decachaetophora, Decachaetophora**
Meroplius*, Meroplius*, Meroplius,
Xenosepsis* Xenosepsis* Xenosepsis,
Nemopodinae:
Perochaeta, Perochaeta**, Perochaeta**,
Lasionemopoda, Lasionemopoda**, Lasionemopoda**,
Nemopoda, Nemopoda, Nemopoda,
Sepsis* Sepsis(Sepsidimorpha) (Sepsidimorpha)
(Sepsidimorpha) classifiedinSepsis
Sepsinae***: Sepsisgroup:
Meropliosepsis, Meropliosepsis(aspart Meropliosepsis**,
ofPalaeosepsis),
Lasiosepsis Lasiosepsis(inSepsis) Lasiosepsis
Palaeosepsinae***:
Palaeosepsis Palaeosepsis, Palaeosepsis**,
Dicranosepsis, Dicranosepsis, Dicranosepsis,
Parapalaeosepsis* Parapalaeosepsis* (the Parapalaeosepsis**
last3asPalaeosepsis)
Neosepsinae***:
Leptomerosepsis, Leptomerosepsis, Leptomerosepsis,
Sepsiss.str. Sepsiss.str.(including Sepsiss.str.,
Sepsidimorphaand Australosepsis
Australosepsis)
*Name ofgenusorsubfamilyadjustedto modem nomenclature.
**Genusnotincludedinoriginalclassificationbutplacementherelikelytoreflectauthor's
opinion.
***DudaprobablyconsideredthePalaeosepsinaeandNeosepsinaesubgroupsoftheSep-
sinaealthoughhisoriginaltableassignsthesameranktoallthreegroups(seeHennig[1949]
forsimilarcomments).
****ClassificationwaspresentedintheCatalogue ofAfrotropical Dipteraand Orygma is
Holarctic.
1996 MEIER: LARVAL MORPHOLOGY OF SEPSIDAE 7
but some have been attracted to and reared containing collecting and rearing records are
fromc(wdung(Cuthbertson, 1937; personal scattered throughout the literature. I have
obs.) while others apparently visit carcasses collectedmuchbiologicalinformation,which
(Braack, 1981). Orygmaluctuosumistheonly issummarizedinashortparagraphfollowing
sepsid exclusively occurring on decaying sea the larval descriptions of each species. Im-
wrack (Egglishaw, 1960). mature sepsids play a major role in the de-
Foralongtime littlewas known about the composition ofcow dung, a process ofgreat
biology ofthe Sepsidae, although the behav- importancefordairyfarming,whichwasonly
ior ofsome species attracted the attention of realized recently when the use ofpesticides
naturalists. IndividualsofSepsisfulgenshave disturbed it sufficiently to cause various
thetendencytoformlargeswarmscontaining problems (e.g., Roncalli, 1989; Waterhouse,
up to an estimated 50,000 individuals. Such 1974). Probably more significant is the role
swarms can be stationary for as long as 30 of sepsids as disease vectors (Zuska, 1960;
days (Pont, 1987b). The swarming ofSepsis ZuskaandLastovka, 1969; Greenberg, 1971).
fulgens has spawned numerous notes in en- Sepsids have been shown to carry bacteria
tomological journals (see Pont, 1987b) and and spores of fungi (Greenberg, 1971) and
is today interpreted as a hibernation phe- occurquiteregularlyinslaughterhouses(Zus-
nomenon (Pont, 1987b), although similar ka, 1960; Greenberg and Bornstein, 1964).
swarming has also been observed in at least However, they are usually outnumbered by
onetropical speciesinCostaRica(Grimaldi, calyptrate flies, and little research on their
personal commun.). In this case, the swarms potentially detrimental activities has been
mainly contained pharate adults and may carried out. Also, adult sepsids rarely visit
have been the result ofmass emergence. food that is intended for human consump-
The otheraspectofsepsidbiology that has tion, which reduces the riskofdisease trans-
been studied extensively is courtship and mission.
mating behavior. The precopulatory guard-
ing by males ofSepsis cynipsea has been the
THE MORPHOLOGY OF SEPSID
subject ofimportant sociobiological studies
LARVAE
(Foster, 1967; Parker, 1972 a, 1972b; Ward,
1983). In precopulatory guarding, the males The small body ofliterature on the mor-
mount the females prior to egg deposition phology ofsepsid larvae (Brindle, 1965; Eg-
and copulation takes place only after the fe- glishaw, 1960; Hennig, 1949, 1952; Mangan,
male has laid her eggs. Therefore, the de- 1977; Ozerov, 1986a, 1987, 1991a; Schu-
posited batch ofeggs is fertilized by sperm mann, 1962)issummarizedinFerrar(1987).
that, during previous copulations, had been Information on 20 species in 7 genera is
transmitted into the spermathecae by other available. They were studied using light-mi-
males. Interestingly, precopulatory guarding croscopical techniques. The morphology of
is observed in a numberofsepsids, although the cephalic region, consisting of head and
ithadonlybeen described fortwo species by thoracic segments, hasreceivedverylittleat-
Parker (1972a, 1972b; Sepsis cynipsea, S. tention in the sepsid and in the remaining
punctum). Katja Schulz and I also observed literature on the morphology of cyclorrha-
this behavior in Sepsis thoracica (Zimbab- phanlarvae (butsee Hennig, 1949). Itishere
wan population, possibly new species), Sal- that the advent of SEM (scanning electron
tella sphondylii, Xenosepsis fukuharai, Pa- microscope)mayhaveitsbiggestimpact.The
laeosepsis mitis, and Palaeosepsis pusio. qualityofthelarvaldescriptionsofimmature
Eberhard (personal commun.) also observed sepsids in the literature is uneven. For ex-
precopulatory guarding in Palaeosepsis div- ample, some small tubercles on the last seg-
ersiformisandtwo otherunidentified species mentwere seen by some authors and missed
ofPalaeosepsis. byothers, orthe pattern ofspines on thelast
Information on the economic importance segmentwasmisidentified (e.g., S. thoracica,
ofsepsids isscarce, suggestingthatitis prob- seeHennig, 1949). This madeitveryhardto
ably minor. Many species are synanthropic evaluate the published information from a
and, unfortunately, the natural history notes cladistic point of view. Fortunately, I was
8 BULLETIN AMERICAN MUSEUM OFNATURAL HISTORY NO. 228
able to studyallpreviously described species tissues. To prevent the retraction ofthe ce-
(except for Saltella orientalis) and revise the phalic region of the larvae during fixation,
descriptions. From my study I have to con- theywere eitherrelaxed ina 10% solution of
clude that most published keys and identi- magnesium sulfate or quickly killed in near-
fication tables should not be used since too boilingwater,thelattertechniquebeingmore
muchemphasis hasbeenplacedonthe num- effective.
beroflobesontheanteriorspiracles. Studied ThefixationoflarvalSchizophoraforSEM
across a large number ofspecies, this char- has been described asproblematic (Grodow-
acterislargelycontinuous.Itcanonlybeused itz et al., 1982; Colwell and Kokko, 1986;
for species identification within certain gen- Ferrar, 1987; Ruiz-Martinez, 1989), andsev-
era. eraldifferenttechniqueshavebeenproposed.
Some are technically complicated and ex-
pensive (Colwell and Kokko, 1986), others
MATERIALS AND METHODS
involve extremely toxic chemicals (Grodow-
The larvae of52 species from 16 ofthe 23 itzetal., 1982). Ifoundthatpreservinglarvae
sepsidgenerawerestudiedwiththeaidofthe in a traditional fixative, alcoholic Bouin, or
SEM (see table 3). Since only the larvae of even 70% alcohol yielded good results with
every fifth described species ofthe Sepsidae very little distortion of even the delicate
was available for study, the larval apomor- structures. Afterleavingthelarvaeforatleast
phies may not always refer to entire genera 2 hours in the fixative, they were transferred
but only to speciesgroups within the genera. in 10%stepsinto 100%ethanol,critical-point-
Thus, the results of this study should "be dried, and sputter coated.
regarded only as a provocation for further For each species the same nine views of
investigation" (Wood and Borkent, 1989). thesamelarvalstructureswerestudiedunder
For outgroup comparison, the immatures a SEM (Philips SEM 515): cephalic region,
oftwo species ofthe putative sistergroup of ventral and lateral view; anterior spiracle;
the Sepsidae, the Ropalomeridae (Williston- posterior spiracle; maxillary sensory organ;
iellapleuropunctata, andanunidentifiedRo- last abdominal segment, ventral, lateral, and
palomera), two species of the Coelopidae dorsal; creeping welt. Illustrations were pre-
(Coelopa frigida and Chaetocoelopa sydne- pared from 18 x 13 cm micrographs, since
yensis), and a species of the Dryomyzidae thepreservation andcleanlinessofthelarvae
(Neuroctena caucasica) were studied. Except were too uneven to document the morphol-
forabriefdescription (Lopes, 1932), the lar- ogy for all species and genera with micro-
vae of the Ropalomeridae were not known graphs. For Nemopoda speiseri the cephalic
prior to this work. region could not be studied because it was
Larvae for some species were provided by retractedinallspecimens. Onlypartialviews
K.Schulz(Berlin/Tucson)andimmaturesfor ofthecephalicregionwereavailableforNem-
many more species by Dr. A. L. Ozerov opoda pectinulata. Drawings of the cephal-
(Moscow). Alistofspeciesandcollectingsites opharyngeal skeletons will beforthcomingin
isprovidedinthedescriptions. Larvaewhich Ozerov and Meier (1995).
I collected were preserved from cultures es- Measurements were taken with the aid of
tablished by field-caught females. Normally, an electronic measurement board. Arithme-
single females were placed in a container, tic means and standard deviations are given
provided with substrate, and allowed to lay only when more than five specimens were
eggs. Some ofthelarvaewhich hatched from available for study. The size of third instar
the eggs were preserved and others were al- larvaecanvaryconsiderablybecausemostof
lowedtocompletedevelopment. Malesofthe the larval growth takes place during this life
F1 generation were used for species identifi- stage. Also, sepsids are known for their con-
cation. It is very important that larvae be siderablesizevariabilitywithinaspecies.De-
cleanedbeforebeingpreservedinalcohol.The pendingontheavailabilityoffood,theweight
easiest and most efficient way is to use a so- ofindividualswithinSepsispunctumcanvary
lution ofregular liquid household detergent by a factor often (Zerbe, 1993). Most mea-
or to let the maggots crawl through moist surements reported in this study were taken