BACKGROUND
the order passeriformes, also called passerines or perching-birds, is the largest of the  <dig> orders within the class aves, including ~60% of all ~ <dig> living bird species  <cit> .
the passerines are divided into three major groups, with acanthisittidae  being sister to the two large parvorders oscines and suboscines  <cit> .
oscines, “true” songbirds, possess a complex syrinx, which enables them to perform complex songs, whereas suboscines do not have this characteristic  <cit> .
passerida, the largest group within oscines, can only be delimited by an insertion of one amino acid in exon  <dig> of the c-myc gene  <cit> , but no synapomorphic morphological character is known to define this taxon.
within passerida, the superfamily sylvioidea has proved difficult to delineate based on morphology, because of apparent multiple events of convergent evolution [e.g.
<cit> .
several of these studies found evidence that sylvioidea sensu sibley and ahlquist  <cit>  and sibley and monroe  <cit> , which was based on dna-dna hybridization studies, was not monophyletic.
recently, sylvioidea has gone through a profound rearrangement based on various sets of molecular sequence data  <cit> .
these studies showed that several of the families and subfamilies established by sibley and ahlquist  <cit>  were non-monophyletic.
the first comprehensive study of the whole superfamily, by alström et al.
<cit> , was based on one nuclear and one mtdna sequence.
that study identified  <dig> well supported major clades, which were proposed to be recognized at the family level.
one of the consequences of that revision was a temporary loss of the family name sylviidae, which was previously recognized as the largest family within sylvioidea.
as the type genus of sylviidae leach,  <dig>  sylvia, was shown to be nested within the large timaliidae vigors and horsfield,  <dig> assemblage, it was suggested to suppress sylviidae, following the principle of stability  <cit> .
however, sylviidae was re-established by gelang et al.
<cit> , to coexist as a separate family along with timaliidae.
superscript numbers in second column refer to numbers in third column, indicating new family affiliations.
genera in brackets give the name used by dickinson  <cit> , which have changed according to gill and donsker  <cit> .
*no longer included in sylvioidea.
despite the numerous studies on large-scale relationships within sylvioidea, the relationships among the families are still largely unresolved.
we here present a multilocus analysis of one mitochondrial and six nuclear markers, ~ <dig> aligned basepairs for  <dig> species with the aim to clarify the phylogeny.
RESULTS
sequence statistics
the combined dataset comprised  <dig> aligned basepairs of nucleotide sequence data, one mitochondrial and six nuclear markers.
percentage of parsimony informative sites were as follows: recombination activating gene  <dig>  34% , fibrinogen beta chain  36% , glyceraldehyde-3-phosphate dehydrogenase  38% , myoglobin  42% , ornithine decarboxylase  <dig>  45% , mtdna cytochrome b  46% , and lactate dehydrogenase b  47% .
garli-part found the tree with the highest likelihood in  <dig> of all  <dig> runs, the next best tree was found in  <dig> of the runs.
these trees differed only in the topology of the outgroup taxa.
thus, in  <dig> out of  <dig> inferences, garli-part found the same topology within sylvioidea, which was identical to the bayesian inference  50% majority rule tree with respect to the relationships within sylvioidea.
in the bi, 80/78%  of the nodes were well supported , 17/17% had pps between  <dig>  and  <dig> , and only 2/5% of the nodes were unresolved.
in the ml analyses, 61/50% of the nodes had support values ≥85%, 26/28% between 50% and 84%, and 13/22% <50%.
phylogeny of sylvioidea
the tree based on the complete dataset is shown in figure  <dig>  and the tree based on the nuclear dataset is shown in figure  <dig>  with the results from the single-locus analyses indicated in the latter figure.
there is generally good agreement between these two trees.
the same applies to the analysis in  <dig> partitions, which recovered basically the same topology with similar nodal support, and with no well supported conflicts.
all families in sylvioidea  had pp  <dig>  and ml bootstrap support 100%, except macrosphenidae and cettiidae sensu gill and donsker  <cit>  .
nicatoridae, alaudidae and panuridae were sister to all other sylvioid taxa , with pp  <dig>  but lower ml bootstrap support.
the sister relationship of alaudidae and panuridae was highly supported in the combined and nuclear analyses.
macrosphenidae was sister to the other sylvioid families , albeit less supported in the ml bootstrap analyses of the combined data set.
the remaining families were divided into two major clades,  <dig> and  <dig>  clade  <dig> consisted of cisticolidae, locustellidae, bernieridae, donacobiidae, acrocephalidae, and pnoepygidae.
these relationships were mostly only supported by bi, although clade  <dig>  containing bernieridae, donacobiidae and locustellidae, was strongly supported by both bi and ml.
the sister relationship of donacobiidae and bernieridae  was weakly supported in all analyses.
the sister clade to cisticolidae  had varying support in the combined and nuclear analyses.
the largest clade  was poorly supported, with a basal polytomy consisting of hirundinidae, pycnonotidae and a clade  containing the remaining families.
within clade  <dig>  the strongly supported clade  <dig> comprised zosteropidae, timaliidae, pellorneidae, and leiothrichidae with sylviidae as their common sister group.
the relationships among the families in clade  <dig> were uncertain, and differed between the analysis of the complete dataset and the one based on only nuclear loci.
the sister relationship between leiothrichidae and pellorneidae, only weakly supported in the combined data set, was well  supported in the nuclear data set, but not well by ml.
clade  <dig> formed the sister clade to the sylviid/timaliid taxa , although the clade  containing these two clades received low ml bootstrap support.
within clade  <dig>  phylloscopidae was sister to a clade  containing aegithalidae and a non-monophyletic cettiidae.
the sister relationship of aegithalidae and the cettiid genus hylia was poorly supported.
the clade containing erythrocercus, scotocerca and other cettiidae  was well supported, especially by the nuclear data set, as was the scotocerca/other cettiidae clade .
there were only few strongly supported incongruences: 1) the sister relationship of ammomanes deserti and mirafra javanica  found by the complete and nuclear data sets, was strongly contradicted  by the single-locus analyses of mb, gapdh and mt-cyb, which instead supported a sister relationship of alauda arvensis and mirafra javanica.
2) sinosuthora webbiana was placed in pellorneidae by fgb .
3) donacobius was sister to locustellidae based on fgb, but sister to bernieridae using odc <dig>  4) trochalopteron elliotii was placed in pellorneidae and not in leiothrichidae in the gapdh tree .
indels
most families had unique insertions and/or deletions , which lent further support to these clades .
however, few indels were shared by two or more families .
the grouping of panuridae with alaudidae was supported by an insertion of  <dig> bp in odc <dig>  erythrocercus and scotocerca shared a  <dig> bp deletion in odc <dig> with the other cettiidae, except hylia.
a  <dig> bp deletion in mb was shared by the taxa in clade  <dig> , but this was also found in pycnonotidae and hirundinidae, which were inferred to be more distantly related.
two deletions of three basepairs in fgb and mb, respectively, delimited sylvioidea from the outgroup, including paridae, remizidae and stenostiridae.
the inclusion of eremomela in cisticolidae was supported by several shared indels.
discussion
phylogeny of sylvioidea
the present study is the most comprehensive analysis of the superfamily sylvioidea, both with respect to the number of taxa and the number of loci.
bi and ml searches found identical topologies, which reinforces the confidence in the results, even though the strength of the support differed between these methods.
only few deeper nodes  were supported by single-locus analyses.
mb and odc <dig> provided most resolution deep in the tree, and mb was the only single marker that supported sylvioidea as a monophyletic group in the bi and ml bootstrap.
the best ml trees for fgb and rag <dig> also inferred sylvioidea to be monophyletic, but this was not supported by their respective bootstrap analyses.
thus, the concatenation of all markers improved the resolution substantially.
the overall support of the multilocus tree, especially of the deeper nodes, is much improved compared to previous studies  <cit> .
especially studies using only mitochondrial data have failed to resolve most nodes below family level  <cit> .
however, also an analysis by johansson et al.
<cit>  of a dataset comprising six loci  for  <dig> sylvioid taxa was largely unresolved.
the short internodes and lack of resolution deep in the tree suggest a rapid radiation of the families within sylvioidea.
the sister relationship of alaudidae and panuridae, which is extremely unexpected from a morphological and ecological perspective, was very well supported, also by several single-locus analyses.
this relationship has been found also in previous studies based on fewer, but partly the same, loci  <cit> .
the precise position of the enigmatic nicatoridae still has to be regarded as uncertain.
the position of macrosphenidae as sister to the remaining sylvioid taxa was well supported in the bi but less so in the ml bootstrap analyses.
this has previously been found based on different taxon samplings and partly different loci  <cit> .
in contrast, in studies where only one mitochondrial and one nuclear loci were used  <cit>  macrosphenidae was placed in a more derived position within sylvioidea.
the two large clades  <dig> and  <dig> have been inferred in two previous studies based on different taxon sampling and some of the same loci as in the present analysis  <cit> , although they have not been recovered in other studies based on different taxon sampling and partly different loci  <cit> .
as they were poorly supported here, they are to be considered as highly tentative.
clade  <dig> in general was also found by various studies, but with differing constellations.
while clade  <dig> was quite consistently recovered in previous studies  <cit> , as well as in studies lacking either donacobiidae or bernieridae  <cit> , the relationships among clade  <dig>  acrocephalidae and pnoepygidae varied.
the latter family was found as sister to clade  <dig> and acrocephalidae  <cit>  or in different positions  <cit> , though never well supported.
lei et al.
<cit>  found in a study based solely on mitochondrial sequences a close relationship between locustellidae and cisticolidae, but with acrocephalidae falling in another clade, with high support in the bayesian analysis, but with only low ml bootstrap support.
the largest clade  was divided into a polytomy formed by pycnonotidae, hirundinidae and clade  <dig>  pycnonotidae, hirundinidae and clade  <dig> shared a  <dig> bp deletion in mb that was not found in clade  <dig>  due to the somewhat uncertain relationships in the deeper nodes in this part of the tree, different scenarios are possible.
one is that this deletion was reversed by the members of clade  <dig>  or that the different families lost these base pairs independently.
alternatively, the homoplastic appearance of this indel could be a case of hemiplasy  <cit> , where the gene tree is not congruent with the species tree due to lineage sorting.
hemiplasy is considered to be more likely when internodes are short  <cit> , as is the case in this clade.
in a study of transposable elements over a wide range of birds, cases of homoplasy were found, but lineage sorting was considered an unlikely explanation of these events  <cit> .
however, indels seem to be more prone to homoplasy than insertions of transposable elements [cf.
<cit> .
clade  <dig> was recovered also by johansson et al.
<cit>  .
within clade  <dig>  clade  <dig> consisted of the much debated sylviid/timaliid families.
all these families had very high support in our study, as well as the whole clade itself , whereas the latter was only weakly supported in the ml analysis in gelang et al.
<cit> .
the relationships among the families in clade  <dig> agreed with gelang et al.
<cit> , although they were better supported in the latter study, which was based on a much denser taxon sampling but fewer loci than the present study.
sylviidae, when studied in larger sample sizes together with former timaliidae and based on more than one locus  <cit> , was always found as a separate clade.
gelang et al.
<cit>  recognised leiothrichinae, pellorneinae, timaliinae and zosteropinae as subfamilies within timaliidae, whereas gill and donsker  <cit>  elevated these to family rank.
we support the latter treatment, as it is more on a par with the treatment of the other groups within sylvioidea.
the close affinities of phylloscopidae, aegithalidae and cettiidae  were well supported by our nuclear data set, although the relationships among these are not unanimously well supported by both bi and ml.
this clade had been found previously  <cit> , although with weaker support.
the latter study  <cit>  also noted morphological similarities between cettiidae sensu alström et al.
<cit> , scotocercaerythrocercus and aegithalidae, especially between the first two .
the families paridae, remizidae and stenostiridae are sometimes included in sylvioidea [e.g.
<dig> ,  <cit> .
based on the phylogeny presented here, additional evidence from indels, and previous studies, we recommend that these three families are not included in sylvioidea, and accordingly that sylvioidea is circumscribed as in figures  <dig> and  <dig>
intrafamilial relationships
macrosphenidae was the least supported family within sylvioidea, and none of the single-locus analyses recovered this group with high support.
this is probably the result of long divergence times among the different species or species pairs included here, as indicated by long branches.
this clade contains species that are morphologically and ecologically highly divergent, and this in combination with some long internodes within this clade suggest that a number of extant and/or extinct taxa also belong here.
in addition to the genera included here, also achaetops has been shown to belong in this group  <cit> .
our results confirm the general structure within cisticolidae recovered by nguembock et al.
<cit> .
we also corroborate the sister relationship of calamonastes and camaroptera, which had previously been inferred based on single-locus analyses only  <cit> .
johansson et al.
<cit>  suggested eremomela to be nested within cisticolidae , contra dickinson  <cit> , who placed it in phylloscopinae.
however, they found contradicting evidence in their study: odc <dig> and mb supported a close relationship with apalis, while fgb placed eremomela as sister to prinia .
our combined analyses placed eremomela with high support in the clade including apalis.
the present study included six out of the eight genera and six out of the eleven species in the malagasy endemic bernieridae, and is the most complete analysis of this family to date with respect to number of loci, although one mitochondrial study included three additional species   <cit> , and one study based on mb, odc <dig>  ldh, gapdh and mt-cyb also included the monotypic genus cryptosylvicola <cit> .
all of the relationships inferred in the present study were strongly supported, except for the sister relationship between hartertula and thamnornis.
clade  <dig> consisted of aegithalidae and cettiidae .
alström et al.
<cit>  noted that cettiidae and scotocerca shared certain morphological characters, such as  <dig> rectrices, whereas most passerines have  <dig>  while erythrocercus and scotocerca were clearly related to cettiidae sensu alström et al.
<cit>  in the present study, a close affiliation of hylia to cettiidae is questionable.
hylia has proved to be difficult to place before  <cit> , although beresford et al.
<cit>  found strong support for an unresolved hylia/ aegithalos/ cettia clade based on the nuclear rag <dig> and rag <dig>  however, strong support was found for a sister relationship between hylia and pholidornis based on mitochondrial nd <dig> and 12s  <cit> .
the latter relationship has previously been suggested based on anatomical details  <cit> , and hylia and pholidornis have been placed in the family hyliidae bannerman,  <dig>  <cit> .
this seems a reasonable treatment, although it would be desirable to include both hylia and pholidornis in a multilocus analysis, preferably including additional loci compared to the present study.
with respect to scotocerca, we suggest that it is better placed in a monotypic family rather than in cettiidae.
it is morphologically and ecologically highly divergent from the cettiidae sensu alström et al.
<cit>  .
moreover, it is separated from cettiidae sensu alström et al.
<cit>  by a long internode, both in the present study and in the one by alström et al.
<cit> .
we therefore propose a new family name:
scotocercidae, fregin, haase, olsson and alström, new family group name
type genus scotocerca sundevall,  <dig>  diagnosis: the genus scotocerca includes a single polytypic species, s. inquieta, which is a small  warbler, with a long, slightly graduated tail with  <dig> feathers ; three prominent rictal bristles; dark hair-like bristles on lower forehead, lores and chin; pale greyish or brownish upperside with some streaking, at least on crown; paler underparts, often more deeply coloured  on flanks, and usually with some streaking on breast; prominent pale supercilium and dark eye-stripe; rectrices rather dark, at least from below, usually with narrow pale tips .
see del hoyo et al.
<cit> , pp.
465– <dig>  and plate  <dig>  p.  <dig>  and alström et al.
<cit> , figure  <dig>
we also suggest that the genus erythrocercus, which includes three species distributed in sub-saharan africa, be treated as a monotypic family rather than in cettiidae.
the same reasons as for scotocerca apply, although erythrocercus is even more different morphologically  <cit> .
we therefore propose a new family name:
erythrocercidae, fregin, haase, olsson and alström, new family group name
type genus erythrocercus hartlaub,  <dig>  diagnosis: small  flycatcher-like warblers, with prominent bristles around base of bill, moderately rounded tail with  <dig> rectrices; variously coloured and patterned plumages .
see del hoyo et al.
<cit> , pp.
327– <dig> and plate  <dig>  p.  <dig>  and alström et al.
<cit> , figure  <dig>
the family name macrosphenidae for the sub-saharan african “sphenoeacus-group” of beresford et al.
<cit>  and johansson et al.
<cit>  is already widely used , but has not been formally described yet.
therefore, we here officially propose the name
macrosphenidae, fregin, haase, olsson and alström, new family group name
for the genera macrosphenussphenoeacusmelocichlaachaetopssylvietta and cryptillas.
type genus macrosphenus cassin,  <dig>  diagnosis: this family is defined based on monophyly .
the different genera are morphologically and ecologically highly divergent, with no known diagnostic morphological characters.
the five species in macrosphenus are 11– <dig>  cm, with rather long, straight bills and  rather short tails; plumage colours subdued, mostly various shades of dull greenish, yellowish, brownish and greyish; inhabits forest .
note that the position of m. kretschmeri in pycnonotidae found by alström et al.
<cit>  was based on a misidentified specimen, as pointed out by johansson et al.
<cit> .
the single species in sphenoeacuss.
afer, is 19– <dig> cm, with a long, strongly graduated, pointed tail; rufous cap, black malar stripe, and heavy streaking above and below; inhabits various grassy and scrubby areas .
the single species in melocichlam.
mentalis, is 18– <dig> cm, with a long, broad, rounded tail; uniformly brown above and paler below with contrastingly dark tail and black malar stripe; inhabits areas with grass and coarse herbage and forest clearings .
the single species in the genus achaetopsa.
pycnopygius, is 16– <dig> cm, heavily streaked above and on breast, with rufous belly and flanks, distinct white supercilium and black malar stripe; inhabits rocky ground on hill sides .
the genus sylvietta contains nine species, which are small  and extremely short-tailed; plumages various shades of grey, rufous, greenish and yellowish, no dark streaking; inhabit mainly forest .
the single species in the genus cryptillasc.
victorini, is 15– <dig> cm, with a fairly long, graduated tail, plain brown upperparts, plain pale rufous underparts, grey ear-coverts and pale orange iris; inhabits low, dense vegetation, often in moist areas .
it was previously placed in the genus bradypterus, but was shown to belong in this clade by beresford et al.
<cit> .
for names proposed after  <dig>  the international code of zoological nomenclature  <cit>  requires “a description or definition that states in words characters that are purported to differentiate the taxon” , or “a bibliographic reference to such a published statement” .
as is evident from the above description of the family macrosphenidae, it can be very problematic, or even impossible, to meet these requirements for family-group names  that are defined based on clades in molecular-based phylogenies.
in the case of macrosphenidae, no diagnostic morphological characters that are shared by all its members are known, and in view of the enormous morphological diversity within this clade , it is possible that no such characters will ever be found.
we have registered this publication in zoobank under the following lsid: urn:lsid:zoobank.org:pub:db5adcc7-69d5-42ad-bcbe-b58bac2c512a.
CONCLUSIONS
the present study is the most comprehensive analysis of the superfamily sylvioidea, both with respect to the number of taxa and the number of loci.
the inferred tree is generally well resolved and well supported.
however, several nodes deep in the tree remain uncertain, probably as a result of a rapid radiation of the families within sylvioidea.
all families except cettiidae  were strongly supported.
although the phylogenetic position of hylia was uncertain, we tentatively support the recognition of the family hyliidae bannerman,  <dig> for this genus and pholidornis.
we propose new family names for the genera scotocerca and erythrocercus, scotocercidae and erythrocercidae, respectively, and we formally propose the name macrosphenidae, which has been in informal use for some time.
we recommend that paridae, remizidae and stenostiridae are not included in sylvioidea.

 the order passeriformes, also called passerines or perching-birds, is the largest of the orders within the class aves, including ~60% of all ~ living bird species. the passerines are divided into three major groups, with acanthisittidae being sister to the two large parvorders oscines and suboscines. oscines, “true” songbirds, possess a complex syrinx, which enables them to perform complex songs, whereas suboscines do not have this characteristic. passerida, the largest group within oscines, can only be delimited by an insertion of one amino acid in exon of the c-myc gene, but no synapomorphic morphological character is known to define this taxon. within passerida, the superfamily sylvioidea has proved difficult to delineate based on morphology, because of apparent multiple events of convergent evolution [e.g.. several of these studies found evidence that sylvioidea sensu sibley and ahlquist and sibley and monroe, which was based on dna-dna hybridization studies, was not monophyletic. recently, sylvioidea has gone through a profound rearrangement based on various sets of molecular sequence data. these studies showed that several of the families and subfamilies established by sibley and ahlquist were non-monophyletic. the first comprehensive study of the whole superfamily, by alström et al., was based on one nuclear and one mtdna sequence. that study identified well supported major clades, which were proposed to be recognized at the family level. one of the consequences of that revision was a temporary loss of the family name sylviidae, which was previously recognized as the largest family within sylvioidea. as the type genus of sylviidae leach, sylvia, was shown to be nested within the large timaliidae vigors and horsfield, assemblage, it was suggested to suppress sylviidae, following the principle of stability. however, sylviidae was re-established by gelang et al., to coexist as a separate family along with timaliidae. superscript numbers in second column refer to numbers in third column, indicating new family affiliations. genera in brackets give the name used by dickinson, which have changed according to gill and donsker. *no longer included in sylvioidea. despite the numerous studies on large-scale relationships within sylvioidea, the relationships among the families are still largely unresolved. we here present a multilocus analysis of one mitochondrial and six nuclear markers, ~ aligned basepairs for species with the aim to clarify the phylogeny.  sequence statistics the combined dataset comprised aligned basepairs of nucleotide sequence data, one mitochondrial and six nuclear markers. percentage of parsimony informative sites were as follows: recombination activating gene 34%, fibrinogen beta chain 36%, glyceraldehyde-3-phosphate dehydrogenase 38%, myoglobin 42%, ornithine decarboxylase 45%, mtdna cytochrome b 46%, and lactate dehydrogenase b 47%. garli-part found the tree with the highest likelihood in of all runs, the next best tree was found in of the runs. these trees differed only in the topology of the outgroup taxa. thus, in out of inferences, garli-part found the same topology within sylvioidea, which was identical to the bayesian inference 50% majority rule tree with respect to the relationships within sylvioidea. in the bi, 80/78% of the nodes were well supported, 17/17% had pps between and, and only 2/5% of the nodes were unresolved. in the ml analyses, 61/50% of the nodes had support values ≥85%, 26/28% between 50% and 84%, and 13/22% <50%. phylogeny of sylvioidea the tree based on the complete dataset is shown in figure and the tree based on the nuclear dataset is shown in figure with the results from the single-locus analyses indicated in the latter figure. there is generally good agreement between these two trees. the same applies to the analysis in partitions, which recovered basically the same topology with similar nodal support, and with no well supported conflicts. all families in sylvioidea had pp and ml bootstrap support 100%, except macrosphenidae and cettiidae sensu gill and donsker. nicatoridae, alaudidae and panuridae were sister to all other sylvioid taxa, with pp but lower ml bootstrap support. the sister relationship of alaudidae and panuridae was highly supported in the combined and nuclear analyses. macrosphenidae was sister to the other sylvioid families, albeit less supported in the ml bootstrap analyses of the combined data set. the remaining families were divided into two major clades, and clade consisted of cisticolidae, locustellidae, bernieridae, donacobiidae, acrocephalidae, and pnoepygidae. these relationships were mostly only supported by bi, although clade containing bernieridae, donacobiidae and locustellidae, was strongly supported by both bi and ml. the sister relationship of donacobiidae and bernieridae was weakly supported in all analyses. the sister clade to cisticolidae had varying support in the combined and nuclear analyses. the largest clade was poorly supported, with a basal polytomy consisting of hirundinidae, pycnonotidae and a clade containing the remaining families. within clade the strongly supported clade comprised zosteropidae, timaliidae, pellorneidae, and leiothrichidae with sylviidae as their common sister group. the relationships among the families in clade were uncertain, and differed between the analysis of the complete dataset and the one based on only nuclear loci. the sister relationship between leiothrichidae and pellorneidae, only weakly supported in the combined data set, was well supported in the nuclear data set, but not well by ml. clade formed the sister clade to the sylviid/timaliid taxa, although the clade containing these two clades received low ml bootstrap support. within clade phylloscopidae was sister to a clade containing aegithalidae and a non-monophyletic cettiidae. the sister relationship of aegithalidae and the cettiid genus hylia was poorly supported. the clade containing erythrocercus, scotocerca and other cettiidae was well supported, especially by the nuclear data set, as was the scotocerca/other cettiidae clade. there were only few strongly supported incongruences: 1) the sister relationship of ammomanes deserti and mirafra javanica found by the complete and nuclear data sets, was strongly contradicted by the single-locus analyses of mb, gapdh and mt-cyb, which instead supported a sister relationship of alauda arvensis and mirafra javanica. 2) sinosuthora webbiana was placed in pellorneidae by fgb. 3) donacobius was sister to locustellidae based on fgb, but sister to bernieridae using odc 4) trochalopteron elliotii was placed in pellorneidae and not in leiothrichidae in the gapdh tree. indels most families had unique insertions and/or deletions, which lent further support to these clades. however, few indels were shared by two or more families. the grouping of panuridae with alaudidae was supported by an insertion of bp in odc erythrocercus and scotocerca shared a bp deletion in odc with the other cettiidae, except hylia. a bp deletion in mb was shared by the taxa in clade, but this was also found in pycnonotidae and hirundinidae, which were inferred to be more distantly related. two deletions of three basepairs in fgb and mb, respectively, delimited sylvioidea from the outgroup, including paridae, remizidae and stenostiridae. the inclusion of eremomela in cisticolidae was supported by several shared indels. discussion phylogeny of sylvioidea the present study is the most comprehensive analysis of the superfamily sylvioidea, both with respect to the number of taxa and the number of loci. bi and ml searches found identical topologies, which reinforces the confidence in the results, even though the strength of the support differed between these methods. only few deeper nodes were supported by single-locus analyses. mb and odc provided most resolution deep in the tree, and mb was the only single marker that supported sylvioidea as a monophyletic group in the bi and ml bootstrap. the best ml trees for fgb and rag also inferred sylvioidea to be monophyletic, but this was not supported by their respective bootstrap analyses. thus, the concatenation of all markers improved the resolution substantially. the overall support of the multilocus tree, especially of the deeper nodes, is much improved compared to previous studies. especially studies using only mitochondrial data have failed to resolve most nodes below family level. however, also an analysis by johansson et al. of a dataset comprising six loci for sylvioid taxa was largely unresolved. the short internodes and lack of resolution deep in the tree suggest a rapid radiation of the families within sylvioidea. the sister relationship of alaudidae and panuridae, which is extremely unexpected from a morphological and ecological perspective, was very well supported, also by several single-locus analyses. this relationship has been found also in previous studies based on fewer, but partly the same, loci. the precise position of the enigmatic nicatoridae still has to be regarded as uncertain. the position of macrosphenidae as sister to the remaining sylvioid taxa was well supported in the bi but less so in the ml bootstrap analyses. this has previously been found based on different taxon samplings and partly different loci. in contrast, in studies where only one mitochondrial and one nuclear loci were used macrosphenidae was placed in a more derived position within sylvioidea. the two large clades and have been inferred in two previous studies based on different taxon sampling and some of the same loci as in the present analysis, although they have not been recovered in other studies based on different taxon sampling and partly different loci. as they were poorly supported here, they are to be considered as highly tentative. clade in general was also found by various studies, but with differing constellations. while clade was quite consistently recovered in previous studies, as well as in studies lacking either donacobiidae or bernieridae, the relationships among clade acrocephalidae and pnoepygidae varied. the latter family was found as sister to clade and acrocephalidae or in different positions, though never well supported. lei et al. found in a study based solely on mitochondrial sequences a close relationship between locustellidae and cisticolidae, but with acrocephalidae falling in another clade, with high support in the bayesian analysis, but with only low ml bootstrap support. the largest clade was divided into a polytomy formed by pycnonotidae, hirundinidae and clade pycnonotidae, hirundinidae and clade shared a bp deletion in mb that was not found in clade due to the somewhat uncertain relationships in the deeper nodes in this part of the tree, different scenarios are possible. one is that this deletion was reversed by the members of clade or that the different families lost these base pairs independently. alternatively, the homoplastic appearance of this indel could be a case of hemiplasy, where the gene tree is not congruent with the species tree due to lineage sorting. hemiplasy is considered to be more likely when internodes are short, as is the case in this clade. in a study of transposable elements over a wide range of birds, cases of homoplasy were found, but lineage sorting was considered an unlikely explanation of these events. however, indels seem to be more prone to homoplasy than insertions of transposable elements [cf.. clade was recovered also by johansson et al.. within clade clade consisted of the much debated sylviid/timaliid families. all these families had very high support in our study, as well as the whole clade itself, whereas the latter was only weakly supported in the ml analysis in gelang et al.. the relationships among the families in clade agreed with gelang et al., although they were better supported in the latter study, which was based on a much denser taxon sampling but fewer loci than the present study. sylviidae, when studied in larger sample sizes together with former timaliidae and based on more than one locus, was always found as a separate clade. gelang et al. recognised leiothrichinae, pellorneinae, timaliinae and zosteropinae as subfamilies within timaliidae, whereas gill and donsker elevated these to family rank. we support the latter treatment, as it is more on a par with the treatment of the other groups within sylvioidea. the close affinities of phylloscopidae, aegithalidae and cettiidae were well supported by our nuclear data set, although the relationships among these are not unanimously well supported by both bi and ml. this clade had been found previously, although with weaker support. the latter study also noted morphological similarities between cettiidae sensu alström et al., scotocercaerythrocercus and aegithalidae, especially between the first two. the families paridae, remizidae and stenostiridae are sometimes included in sylvioidea [e.g.,. based on the phylogeny presented here, additional evidence from indels, and previous studies, we recommend that these three families are not included in sylvioidea, and accordingly that sylvioidea is circumscribed as in figures and intrafamilial relationships macrosphenidae was the least supported family within sylvioidea, and none of the single-locus analyses recovered this group with high support. this is probably the result of long divergence times among the different species or species pairs included here, as indicated by long branches. this clade contains species that are morphologically and ecologically highly divergent, and this in combination with some long internodes within this clade suggest that a number of extant and/or extinct taxa also belong here. in addition to the genera included here, also achaetops has been shown to belong in this group. our results confirm the general structure within cisticolidae recovered by nguembock et al.. we also corroborate the sister relationship of calamonastes and camaroptera, which had previously been inferred based on single-locus analyses only. johansson et al. suggested eremomela to be nested within cisticolidae, contra dickinson, who placed it in phylloscopinae. however, they found contradicting evidence in their study: odc and mb supported a close relationship with apalis, while fgb placed eremomela as sister to prinia. our combined analyses placed eremomela with high support in the clade including apalis. the present study included six out of the eight genera and six out of the eleven species in the malagasy endemic bernieridae, and is the most complete analysis of this family to date with respect to number of loci, although one mitochondrial study included three additional species, and one study based on mb, odc ldh, gapdh and mt-cyb also included the monotypic genus cryptosylvicola. all of the relationships inferred in the present study were strongly supported, except for the sister relationship between hartertula and thamnornis. clade consisted of aegithalidae and cettiidae. alström et al. noted that cettiidae and scotocerca shared certain morphological characters, such as rectrices, whereas most passerines have while erythrocercus and scotocerca were clearly related to cettiidae sensu alström et al. in the present study, a close affiliation of hylia to cettiidae is questionable. hylia has proved to be difficult to place before, although beresford et al. found strong support for an unresolved hylia/ aegithalos/ cettia clade based on the nuclear rag and rag however, strong support was found for a sister relationship between hylia and pholidornis based on mitochondrial nd and 12s. the latter relationship has previously been suggested based on anatomical details, and hylia and pholidornis have been placed in the family hyliidae bannerman,. this seems a reasonable treatment, although it would be desirable to include both hylia and pholidornis in a multilocus analysis, preferably including additional loci compared to the present study. with respect to scotocerca, we suggest that it is better placed in a monotypic family rather than in cettiidae. it is morphologically and ecologically highly divergent from the cettiidae sensu alström et al.. moreover, it is separated from cettiidae sensu alström et al. by a long internode, both in the present study and in the one by alström et al.. we therefore propose a new family name: scotocercidae, fregin, haase, olsson and alström, new family group name type genus scotocerca sundevall, diagnosis: the genus scotocerca includes a single polytypic species, s. inquieta, which is a small warbler, with a long, slightly graduated tail with feathers; three prominent rictal bristles; dark hair-like bristles on lower forehead, lores and chin; pale greyish or brownish upperside with some streaking, at least on crown; paler underparts, often more deeply coloured on flanks, and usually with some streaking on breast; prominent pale supercilium and dark eye-stripe; rectrices rather dark, at least from below, usually with narrow pale tips. see del hoyo et al., pp. 465– and plate p. and alström et al., figure we also suggest that the genus erythrocercus, which includes three species distributed in sub-saharan africa, be treated as a monotypic family rather than in cettiidae. the same reasons as for scotocerca apply, although erythrocercus is even more different morphologically. we therefore propose a new family name: erythrocercidae, fregin, haase, olsson and alström, new family group name type genus erythrocercus hartlaub, diagnosis: small flycatcher-like warblers, with prominent bristles around base of bill, moderately rounded tail with rectrices; variously coloured and patterned plumages. see del hoyo et al., pp. 327– and plate p. and alström et al., figure the family name macrosphenidae for the sub-saharan african “sphenoeacus-group” of beresford et al. and johansson et al. is already widely used, but has not been formally described yet. therefore, we here officially propose the name macrosphenidae, fregin, haase, olsson and alström, new family group name for the genera macrosphenussphenoeacusmelocichlaachaetopssylvietta and cryptillas. type genus macrosphenus cassin, diagnosis: this family is defined based on monophyly. the different genera are morphologically and ecologically highly divergent, with no known diagnostic morphological characters. the five species in macrosphenus are 11– cm, with rather long, straight bills and rather short tails; plumage colours subdued, mostly various shades of dull greenish, yellowish, brownish and greyish; inhabits forest. note that the position of m. kretschmeri in pycnonotidae found by alström et al. was based on a misidentified specimen, as pointed out by johansson et al.. the single species in sphenoeacuss. afer, is 19– cm, with a long, strongly graduated, pointed tail; rufous cap, black malar stripe, and heavy streaking above and below; inhabits various grassy and scrubby areas. the single species in melocichlam. mentalis, is 18– cm, with a long, broad, rounded tail; uniformly brown above and paler below with contrastingly dark tail and black malar stripe; inhabits areas with grass and coarse herbage and forest clearings. the single species in the genus achaetopsa. pycnopygius, is 16– cm, heavily streaked above and on breast, with rufous belly and flanks, distinct white supercilium and black malar stripe; inhabits rocky ground on hill sides. the genus sylvietta contains nine species, which are small and extremely short-tailed; plumages various shades of grey, rufous, greenish and yellowish, no dark streaking; inhabit mainly forest. the single species in the genus cryptillasc. victorini, is 15– cm, with a fairly long, graduated tail, plain brown upperparts, plain pale rufous underparts, grey ear-coverts and pale orange iris; inhabits low, dense vegetation, often in moist areas. it was previously placed in the genus bradypterus, but was shown to belong in this clade by beresford et al.. for names proposed after the international code of zoological nomenclature requires “a description or definition that states in words characters that are purported to differentiate the taxon”, or “a bibliographic reference to such a published statement”. as is evident from the above description of the family macrosphenidae, it can be very problematic, or even impossible, to meet these requirements for family-group names that are defined based on clades in molecular-based phylogenies. in the case of macrosphenidae, no diagnostic morphological characters that are shared by all its members are known, and in view of the enormous morphological diversity within this clade, it is possible that no such characters will ever be found. we have registered this publication in zoobank under the following lsid: urn:lsid:zoobank.org:pub:db5adcc7-69d5-42ad-bcbe-b58bac2c512a.  the present study is the most comprehensive analysis of the superfamily sylvioidea, both with respect to the number of taxa and the number of loci. the inferred tree is generally well resolved and well supported. however, several nodes deep in the tree remain uncertain, probably as a result of a rapid radiation of the families within sylvioidea. all families except cettiidae were strongly supported. although the phylogenetic position of hylia was uncertain, we tentatively support the recognition of the family hyliidae bannerman, for this genus and pholidornis. we propose new family names for the genera scotocerca and erythrocercus, scotocercidae and erythrocercidae, respectively, and we formally propose the name macrosphenidae, which has been in informal use for some time. we recommend that paridae, remizidae and stenostiridae are not included in sylvioidea. 
the genera scotocerca and erythrocercus are closely related to cettiidae, but separated by relatively long internodes. we propose new family names for the genera scotocerca and erythrocercus, scotocercidae and erythrocercidae, respectively, rather than including these in cettiidae, and we formally propose the name macrosphenidae, which has been in informal use for some time. our data do not support the inclusion of hylia in cettiidae, but do not strongly reject a close relationship with cettiidae either. the families paridae, remizidae and stenostiridae clustered among the outgroup taxa and not within sylvioidea. although the phylogenetic position of hylia is uncertain, we tentatively support the recognition of the family hyliidae bannerman, for this genus and pholidornis. we here present a phylogenetic hypothesis for sylvioidea based on one mitochondrial and six nuclear markers, in total ~ kbp, for ingroup species representing all currently recognised families and some species with uncertain affinities, making this the most comprehensive analysis of this taxon. the resolution, especially of the deeper nodes, is much improved compared to previous studies.
 the circumscription of the avian superfamily sylvioidea is a matter of long ongoing debate. while the overall inclusiveness has now been mostly agreed on and families recognised, the phylogenetic relationships among the families are largely unknown. we here present a phylogenetic hypothesis for sylvioidea based on one mitochondrial and six nuclear markers, in total ~ kbp, for ingroup species representing all currently recognised families and some species with uncertain affinities, making this the most comprehensive analysis of this taxon.  the resolution, especially of the deeper nodes, is much improved compared to previous studies. however, many relationships among families remain uncertain and are in need of verification. most families themselves are very well supported based on the total data set and also by indels. our data do not support the inclusion of hylia in cettiidae, but do not strongly reject a close relationship with cettiidae either. the genera scotocerca and erythrocercus are closely related to cettiidae, but separated by relatively long internodes. the families paridae, remizidae and stenostiridae clustered among the outgroup taxa and not within sylvioidea.  although the phylogenetic position of hylia is uncertain, we tentatively support the recognition of the family hyliidae bannerman, for this genus and pholidornis. we propose new family names for the genera scotocerca and erythrocercus, scotocercidae and erythrocercidae, respectively, rather than including these in cettiidae, and we formally propose the name macrosphenidae, which has been in informal use for some time. we recommend that paridae, remizidae and stenostiridae are not included in sylvioidea. we also briefly discuss the problems of providing a morphological diagnosis when proposing a new family-group name based on a clade. phylogenypasserinestaxonomic revisioninternational code of zoological nomenclature 