Unexpected distribution patterns of Carduiceps feather lice (Phthiraptera: Ischnocera: Philopteridae) on sandpipers (Aves: Charadriiformes: Scolopacidae)

Abstract

The louse genus Carduiceps Clay & Meinertzhagen, 1939 is widely distributed on sandpipers and stints (Calidrinae). The current taxonomy includes three species on the Calidrinae (Carduiceps meinertzhageni, Carduiceps scalaris, Carduiceps zonarius) and four species on noncalidrine hosts. We estimated a phylogeny of four of the seven species of Carduiceps (the three mentioned above and Carduiceps fulvofasciatus) from 13 of the 29 hosts based on three mitochondrial loci, and evaluated the relative importance of flyway differentiation (same host species has different lice along different flyways) and flyway homogenization (different host species have the same lice along the same flyway). We found no evidence for either process. Instead, the present, morphology-based, taxonomy of the genus corresponds exactly to the gene-based phylogeny, with all four included species monophyletic. Carduiceps zonarius is found both to inhabit a wider range of hosts than wing lice of the genus Lunaceps occurring on the same group of birds, and to occur on Calidris sandpipers of all sizes, both of which are unexpected for a body louse. The previously proposed family Esthiopteridae is found to be monophyletic with good support. The concatenated dataset suggests that the pigeon louse genus Columbicola may be closely related to the auk and diver louse genus Craspedonirmus. These two genera share some morphological characters with Carduiceps, but no support was obtained for grouping these three genera together. Based on mitochondrial data alone, the relationships among genera within this proposed family cannot be properly assessed, but some previously suggested relationships within this proposed family are confirmed.

Full text

Systematic Entomology (2017), 42, 509– 522 DOI: 10.1111/syen.12227
Unexpected distribution patterns of Carduiceps feather
lice (Phthiraptera: Ischnocera: Philopteridae) on
sandpipers (Aves: Charadriiformes: Scolopacidae)
DANIEL R. GUSTAFSSON
1andURBAN OLSSON
2
1Department of Biology, University of Utah, Salt Lake City, UT, U.S.A. and 2Systematics and Biodiversity, Department of Zoology,
University of Gothenburg, Gothenburg, Sweden
Abstract. The louse genus Carduiceps Clay & Meinertzhagen, 1939 is widely
distributed on sandpipers and stints (Calidrinae). The current taxonomy includes three
species on the Calidrinae (Carduiceps meinertzhageni, Carduiceps scalaris, Carduiceps
zonarius) and four species on noncalidrine hosts. We estimated a phylogeny of four of the
seven species of Carduiceps (the three mentioned above and Carduiceps fulvofasciatus)
from 13 of the 29 hosts based on three mitochondrial loci, and evaluated the relative
importance of yway differentiation (same host species has different lice along different
yways) and yway homogenization (different host species have the same lice along
the same yway). We found no evidence for either process. Instead, the present,
morphology-based, taxonomy of the genus corresponds exactly to the gene-based
phylogeny, with all four included species monophyletic. Carduiceps zonarius is found
both to inhabit a wider range of hosts than wing lice of the genus Lunaceps occurring
on the same group of birds, and to occur on Calidris sandpipers of all sizes, both of
which are unexpected for a body louse. The previously proposed family Esthiopteridae
is found to be monophyletic with good support. The concatenated dataset suggests that
the pigeon louse genus Columbicola may be closely related to the auk and diver louse
genus Craspedonirmus. These two genera share some morphological characters with
Carduiceps, but no support was obtained for grouping these three genera together. Based
on mitochondrial data alone, the relationships among genera within this proposed family
cannot be properly assessed, but some previously suggested relationships within this
proposed family are conrmed.
Introduction
Inuence of yways on louse distribution
The most frequent opportunities for transfer of lice between
two avian host individuals are during mating (Hillgarth, 1996)
or from parents to the young in the nest (Clayton & Tompkins,
1994; Lee & Clayton, 1995). However, lice are likely to exploit
any opportunity to transfer among hosts that arises during the
host’s life cycle. For instance, Brooke & Nakamura (1998)
suggested that cuckoos might gain their cuckoo-specic lice
when groups of cuckoos gather at caterpillar outbreaks during
Correspondence: Daniel R. Gustafsson, Department of Biology, Uni-
versity of Utah, 257 South 1400 East, Salt Lake City, UT 84112, U.S.A.
E-mail: kotatsu.no.leo@gmail.com
migration. Communal sand baths, nest holes and theft of nest
material have also been proposed as likely opportunities for
lateral louse transfer (references in Price et al., 2003).
Gustafsson & Olsson (2012a) suggested that for lice of
shorebirds (Charadriiformes), such opportunities may be very
frequent outside of mating and nesting, due to the ecology of the
host. While host population densities in breeding areas may be
low, shorebirds gather into large, dense ocks during migration.
These ocks follow specic yways, which channel different
populations of the same species into different wintering areas
(e.g. Wilson & Barter, 1998; Tjørve & Tjørve, 2007; Lopes
et al., 2008). Migration and wintering ocks often consist of
a mixture of shorebirds belonging to different species, genera
and even families, and may include shorebird species of very
different body sizes. The size difference between two potential
© 2017 The Royal Entomological Society 509

510 D. R. Gustafsson and U. Olsson
hosts may impede the success rate of louse dispersal from one
host to another (Tompkins et al., 1999; Johnson et al., 2005;
Bush & Clayton, 2006). Conversely, the presence of multiple
host species of similar size in the same mixed ocks may aid
the establishment of lice on novel hosts. Host species like Dun-
lin (Calidris alpina), Sanderling (Calidris alba)andCurlew
Sandpiper (Calidris ferruginea) are of similar size and occur in
sympatry along several yways, with different subpopulations
or subspecies restricted to different yways (Message & Taylor,
2005).
The co-occurrence of potential hosts of similar size in the
same wintering area, and the isolation of different populations
of the same host species into different yways may have two
different effects on their louse populations, if transfer between
hosts happens more frequently during migration than during
breeding. Gustafsson & Olsson (2012a) established the term
‘yway differentiation’ for the scenario in which different popu-
lations of the same host species are parasitized by different louse
species depending on the yway along which hosts migrate.
They further suggested that if louse populations on wintering
hosts encounter a variety of potential host species of similar
body size, and there are no other restrictions to movement
between hosts, the lice may spread laterally to parasitize all
hosts of similar size along one yway, a scenario they termed
‘yway homogenization’. Gustafsson & Olsson (2012a) tested
these hypotheses for the louse genus Lunaceps of sandpipers
(Calidris sensu lato). They found some evidence for yway
homogenization among some, but not all, hosts of similar size
along a yway. However, yway differentiation was not seen
among any of the Lunaceps species sampled from the same host
species from multiple yways.
Most groups of birds are parasitized by multiple genera
of chewing lice (Price et al., 2003). In general, co-occurring
genera of lice on the same host have differentiated to special-
ize in different microhabitats of the host. These microhabitat
specializations are typically correlated with distinct morpholog-
ical traits, which are often convergent between distantly related
louse genera in the same microhabitat (Johnson et al., 2012). For
instance, head lice generally have rounded bodies and large, tri-
angular heads, wing lice (like Lunaceps) usually have elongated,
slender bodies, and body lice (such as Carduiceps) typically
have broad, rounded or triangular heads. Two species of lice
inhabiting different microhabitats of the same host species may
have different rates of straggling to novel hosts, with wing lice
being more likely to switch hosts than body lice (Johnson et al.,
2002; Page et al., 2004; Whiteman et al., 2004). As yway
homogenization relies on the lice being able to transfer easily
between hosts, yway homogenization may be more common
among wing lice than among body lice. By contrast, the poten-
tially more limited capability of dispersal among body lice than
among wing lice may suggest that yway differentiation is
more common among body lice than among wing lice.
We present here a phylogeny of the lice in the genus Car-
duiceps that parasitize sandpipers and allies, based on three
mitochondrial loci, testing the hypothesis that yway homog-
enization may be less common in body lice than in wing lice.
Moreover, yway differentiation may be more common in body
lice than in wing lice, as the lesser propensity for dispersal to
novel hosts among body lice than among wing lice would tend
to isolate the former along different yways.
Taxonomy and relationships of Carduiceps
Carduiceps was described by Clay & Meinertzhagen (1939)
based on head and abdominal characters. The genus mainly par-
asitizes sandpipers (Calidris sensu lato) and godwits (Limosa
spp.), but also the Terek Sandpiper Xenus cinereus and the dow-
itchers (Limnodromus spp.). Most of the hosts of Carduiceps
are also parasitized by the genus Lunaceps, and co-occurrence
of lice in these two genera on the same host is common (D.
Gustafsson & U. Olsson, Unpublished data). Despite the large
overlap in host distribution between these two louse genera
(Price et al., 2003; D. Gustafsson & U. Olsson, Unpublished
data, 2012b), Carduiceps is considered to consist of fewer
species than Lunaceps. This could imply that lice inhabiting
different body parts of sandpipers are subject to different
mechanisms or opportunities for lateral spread to novel hosts.
However, another explanation may be that Carduiceps contains
cryptic species and that the current taxonomy of the genus
based on Timmermann (1954) is too conservative.
The systematics of ischnoceran chewing lice is poorly known,
and all species parasitizing birds are presently placed in one
of three families. Of these, the family Heptapsogastridae is
limited to Neotropical tinamous (Tinamiformes), Goniodi-
dae is largely limited to wildfowl (Galliformes) and pigeons
(Columbiformes), and all other lice are placed in the large and
morphologically diverse Philopteridae. The most thorough alter-
native to this conservative classication was proposed by Eichler
(1963), who divided the Ischnocera parasitizing birds into 17
families and 34 subfamilies. Eichler’s (1963) proposed subdivi-
sion of the Ischnocera has never been widely used, but molecular
evidence suggest that at least some of these groups may be mean-
ingful (Cruickshank et al., 2001). In Eichler’s (1963) proposed
classication, Carduiceps is placed in the family Esthiopteridae,
which he further subdivided into ve subfamilies: Anatoecinae,
Aquanirminae, Columbicolinae, Esthiopterinae and Ibidoeci-
nae. Carduiceps is placed in the subfamily Anatoecinae in
Eichler’s (1963) classication scheme. The family Esthiopteri-
dae contains a variety of louse genera occurring on hosts across
most of the major divisions of birds (Table 1); however, most
of the host groups were placed in the clade Aequorlitornithes
by Prum et al. (2015). Cruickshank et al. (2001) did not nd
any support for Esthiopteridae, but their analysis included only
six of the 15 genera included in the family by Eichler (1963).
No species of Carduiceps have hitherto been included in any
phylogenetic analysis, and the phylogenetic position of this
genus in relation to other shorebird lice is unknown. Eichler
(1963) placed most of the other ischnoceran shorebird lice
in the family Rallicolidae, which was placed together with
Esthiopteridae in his ‘interfamily’ Esthiopteriformia.
We have included representatives of all ve of the proposed
subfamilies of Esthiopteridae suggested by Eichler (1963), to
test whether this family and subfamilies are monophyletic, and
© 2017 The Royal Entomological Society, Systematic Entomology,42, 509– 522

Distribution patterns of Carduiceps 511
Tabl e 1. Host distribution of the lice in Eichler’s (1963) proposed
Esthiopteridae.
Louse genus
Host order
(Clements et al., 2015)
Host clade
(Prum et al., 2015)
Anaticola* Anseriformes Galloanserae
Anatoecus* Anseriformes Galloanserae
Aquanirmus* Podicipediformes Aequorlitornithes
Ardeicola* Pelecaniformes Aequorlitornithes
Ardeiphagus Pelecaniformes Aequorlitornithes
Carduiceps* Charadriiformes Aequorlitornithes
Columbicola* Columbiformes Columbaves
Craspedonirmus* Gaviiformes,
Charadriiformes
Aequorlitornithes
Esthiopterum Gruiformes Gruiformes
Fulicoffula* Gruiformes Gruiformes
Ibidoecus* Pelecaniformes Aequorlitornithes
Neophilopterus Ciconiiformes Aequorlitornithes
Pessaoiella Cuculiformes Columbaves
Turnicola Charadriiformes Aequorlitornithes
Turturicola Columbiformes Columbaves
In addition to the genera listed, Eichler (1963) included Stresemanniella
(now Fulicoffula), Abumarkub (junior synonym of Neophilopterus),
Cereopsoecus and Flamingobius (both now Anatoecus), and Parasori-
cella and Soricella (both now Columbicola). Wilsonia Eichler, 1940, is
preoccupied by Wilsonia Khaln, 1939, and is here replaced with Pes -
saoiella Guimarães, 1940, following Nemésio (2006). Host systematics
follows Clements et al. (2015). The placement of the Hoatzin (Opistho-
comus hoazin) in Cuculiformes by Clements et al. (2015) does not cor-
respond to its phylogenetic placement in Prum et al. (2015). The louse
genus Craspedonirmus is known mainly from divers (Gaviiformes), but
a single species is known from two species of auks (Nelson, 1972). The
genera represented in our analyses are marked with an asterisk (*).
where Carduiceps is placed in relation to the other genera
included in this family by Eichler (1963).
Material and methods
To avoid confusion, the shorebird genus Calidris is here abbrevi-
ated to Cal., whereas the louse genus Carduiceps is abbreviated
Car. Host taxonomy follows Clements et al. (2015).
Sampling
Fresh material of Carduiceps was collected from birds follow-
ing three major yways (Table 2; East Atlantic, East Asian/
Australasian, Pacic Americas) in Sweden during 2007– 2008,
in Japan and Australia during 2008, and in Canada during
2009. Material from Cal. ferruginea,Cal. canutus and different
subspecies of Cal. alpina was collected from two yways (East
Atlantic and East Asian/Australasian). The Cal. alpina and
Cal. canutus samples were collected from host populations
considered divergent enough to belong to different host sub-
species (Message & Taylor, 2005; Clements et al., 2015; see
Table 2). Details about collection of material are the same as in
Gustafsson & Olsson (2012a).
All Carduiceps species used in this study are listed in Table 2.
In addition, representatives of several louse genera belonging to
Eichler’s (1963) Esthiopteridae and Rallicolidae were included
to test the monophyly of Esthiopteridae. Sequences for these lice
were obtained from either GenBank or from our own collections
(see Table 2). Carduiceps lice were assigned to species initially
based on the host they were collected from, but later compared
with Timmermann (1954).
Extraction and sequencing
Prior to DNA extraction, the head and prothorax were cut
off from the posterior part of the body, and extractions were
performed on both parts using DNeasy Blood and Tissue
Kit (Qiagen, Sollentuna, Sweden), following the manufac-
turer’s instructions, with the following exceptions: extraction
was allowed to continue in a water bath for 36 h, and only
one elution (with 100 mL elution uid) was carried out. The
exoskeletons were mounted on slides in Canada balsam as
vouchers after extraction. All vouchers were deposited at the
Natural History Museum, Stockholm (NRM; Swedish mate-
rial), the Price Institute for Parasitological Research (University
of Utah, Salt Lake City, U.S.A.; Canadian and Australian
material), or the Yamashina Institute for Ornithology (Chiba,
Japan; Japanese Material).
Amplication and sequencing of cytochrome coxidase sub-
unit I (COI) used the primers L6625 and H7005 (Hafner
et al., 1994), 12S was sequenced using the primers 12SAI and
12SBI (Simon et al., 1994), and 16S was sequenced using the
primers 16SAR and 16SBR (Simon et al., 1994). Polymerase
chain reactions (PCRs) were performed using GE Healthcare’s
Ready-To-Go beads. PCR protocols followed Yoshizawa &
Johnson (2003) for 12S and 16S, and Hafner et al. (1994) for
COI. A small sample from each PCR product was visualized on
an ethidium bromide or GelRed (Biotium, Gothenburg, Sweden)
gel, and samples showing satisfactory bands were puried using
the EZNA Cycle Pure Kit (Omega) or Exonuclease I +FastAP
(Fermentas Life Sciences, Helsingborg, Sweden) following the
manufacturer’s instructions. Sequencing of puried DNA, using
the same primers as during PCR, was performed in both the for-
ward and reverse directions at Macrogen Inc., South Korea.
In addition to these mitochondrial markers, three nuclear
and one mitochondrial primer sets were examined: elongation
factor 1-𝛼(EF1-For3 and EF1-Cho10; Danforth & Ji, 1998),
long-wavelength opsin (LWRhF and LWRhR; Mardulyn &
Cameron, 1999), NADH dehydroxygenase subunit 5 (F6999
or F7081, and R7495; Yoshizawa, 2004), and LepWG1 and
LepWG2a (Brower & DeSalle, 1998). None of these primer sets
produced any products visible on ethidium bromide gels. The
PCRs using nuclear primer sets were performed in standard,
touch-down (Don et al., 1991) and touch-up (Meusnier et al.,
2008) mode for all primer sets, with no results. All further
analyses were therefore limited to mitochondrial data.
Data treatment
DNA sequences were assembled in  II (DNAStar, Inc.,
Madison, WI, USA) individually for each locus. The 12S and
© 2017 The Royal Entomological Society, Systematic Entomology,42, 509– 522

512 D. R. Gustafsson and U. Olsson
Tabl e 2. Taxa used in this study.
Taxon information GenBank accession numbers
Louse species Host species
Flyway
(location)
Voucher
no. COI 12S 16S
Ingroup
Carduiceps (Car.)fulvofasciatus Xenus cinereus EAs (A) 858 KX865194 – –
860 KX865195 – –
Car. meinertzhageni Calidris (Cal.)alpina alpina EAtl (S) 10-1 KX865170 KX865238 –
19-1 KX865171 KX865239 KX865209
19-2 KX865172 KX865240 KX865210
Cal. alpina schinzii EAtls (S) 224-1 KX865174 KX865245 KX865214
224-2 KX865175 KX865246 KX865215
Cal. alpina sakhalina EAs (J) 775-1 KX865184 – KX865265
775-2 KX865185 – –
Car. scalaris Cal. pugnax EAtl (S) 321-1 KX865176 – –
515-1 JN900135 – KX865221
515-2 KX865183 – KX865222
Car. zonarius Cal. acuminata EAs (A) 954-1 KX865197 – KX865228
956c1 KX865198 – –
Cal. alba EAs (A) 807-1 KX865187 – –
808 KX865188 – –
Cal. canutus canutus EAtl (S) 287-1 JN900121 – KX865217
Cal. canutus rogersi EAs (J) 796-1 KX865186 – KX865223
EAs (A) 824-1 KX865191 – KX865226
853-1 – – KX865227
Cal. ferruginea EAtl (S) 170 JN900108 KX865242 –
EAs (A) 845-1 KX865193 – –
Cal. mauri PA (C) 1480-1 KX865199 KX865255 KX865229
1486 KX865201 KX865257 KX865231
1502 KX865203 KX865260 KX865234
1508 KX865204 KX865261 KX865235
Cal. minuta EAtl (S) 345-1 – KX865248 –
Cal. minutilla PA (C) 1482 KX865200 KX865256 KX865230
1493 – KX865258 KX865232
1495 KX865202 KX865259 KX865233
1539 KX865205 KX865262 KX865236
Cal. pusilla PA (C) 1546 KX865206 KX865263 –
1561 KX865207 KX865264 –
1607 KX865208 – KX865237
Cal. rucollis EAs (A) 816-1 KX865189 – KX865224
817-1 KX865190 – KX865225
843-1 KX865192 – –
Carduiceps sp.aLymnocryptes minimus EAtl (S) 395a1 KX865180 – –
Other Esthiopteridae sensu Eichler (1963)
Anaticola crassicornis Anas strepera – 493 KX865182 KX865254 KX865220
Anaticola rheinwaldi Branta bernicla – 464 JN900116 KX865252 KX865219
Anatoecus sp. Branta bernicla – 462 JN900117 KX865251 KX865218
Aquanirmus rollandii Rollandia rollandi – – DQ314505 – –
Aquanirmus sp. Poliocephalus poliocephalus – – AY314808 AY139889 –
Aquanirmus sp. Tachybaptus novaehollandiae – 950a KX865196 – –
Ardeicola ardeae Ardea cinerea – – AF545677 – –
Ardeicola geronticorum Geronticus calvus – – AF396545 AF396486 –
Columbicola columbae Columba livia – 141 KX865173 – –
Columbicola bacillus Streptopelia decocto – 375a1 KX865179 KX865250 –
Craspedonirmus immer Gavia immer – – AY314810 AY314852 –
Fulicoffula heliornis Heliornis fulica – – AF545701 – –
Fulicoffula longipila Fulica americana – – AF380005 – –
Ibidoecus bisignatus Plegadis chihi – – AY314817 – –
Outgroups
Degeeriella fulva Buteo lagopus – 471 KX865181 KX865253 –
Degeeriella nisus Accipiter nisus – 350 KX865178 KX865249 –
© 2017 The Royal Entomological Society, Systematic Entomology,42, 509– 522

Distribution patterns of Carduiceps 513
Tabl e 2. Continued
Taxon information GenBank accession numbers
Louse species Host species
Flyway
(location)
Voucher
no. COI 12S 16S
Quadraceps auratus Haematopus ostralegus – 276 JN900109 KX865247 KX865216
Quadraceps obtusus Tringa totanus EAtl (S) 69 JN900087 KX865241 KX865211
Rhynonirmus scolopacis Gallinago gallinago EAtl (S) 334 KX865177 – –
Saemundsosnia lockleyi Sterna paradisaea EAtl (S) 215 JN900114 KX865243 KX865212
Saemundssonia sternae Sterna hirundo EAtl (S) 216 JN900113 KX865244 KX865213
aThis specimen could not be reliably identied to any species morphologically.
Flyway abbreviations: EAs, East Asian/Australasian; EAtl, East Atlantic; PA, Pacic Americas. Species not following these yways have been denoted
with a ‘– ’. Location abbreviations: A, Australia; C, Canada; J, Japan; S, Sweden. COI, cytochrome coxidase subunit I. 12S sequences for Degeeriella
spp. were considerably longer than all others and were truncated in both ends to the same lengths as the other aligned sequences. However, full
Degeeriella 12S sequences were submitted to GenBank. All voucher specimens were deposited at the Price Institute for Parasitological Research
(PIPeR), University of Utah, except for the Japanese vouchers, which are deposited at the Yamashina Institute for Ornithology (Chiba, Japan). Voucher
numbers for slides are the same as sample numbers. Missing data are denoted with a ‘– ’. Sample identiers correspond to the same numbers in the
gures. The single sample from Lymnocryptes minimus is not morphologically identiable to species level.
16S sequences were aligned by  as implemented
in  (Biomatters Ltd, Auckland, New Zealand), fol-
lowed by manual adjustment to ensure that similar sequences
in difcult sections were aligned with each other. The COI
sequences were aligned in  (DNA Star, Inc.) and man-
ually inspected and adjusted in - (http://tree.bio.ed.ac.uk/
software/seal/). As useful sequences were obtained for fewer
specimens using the 12S and 16S primer sets, these datasets are
smaller than the COI dataset. For the combined dataset, a single
louse individual from each host species was selected and its indi-
vidual sequences for the three loci were concatenated in *
(Swofford, 2002). For all host species occurring along more than
one yway, we included one louse individual from each yway,
if possible. Uncorrected p-distances were calculated in *
(Swofford, 2002) for the COI dataset separately in order to com-
pare with previous studies.
Data were phylogenetically analysed using Bayesian inference
(BI). The choice of model for the partitions in BI was determined
based on the Akaike information criterion (Akaike, 1973)
calculated in   (Nylander, 2004). In COI, rst,
second and third positions were modelled separately.
Gene trees were estimated by BI using  3.1.2
(Huelsenbeck & Ronquist, 2001, 2005) according to the follow-
ing: (i) all loci were analysed separately (single-locus analyses,
SLAs); (ii) sequences were concatenated all loci together (mul-
tilocus analysis). In the multilocus analysis, the data were parti-
tioned by locus and by codon position, using rate multipliers to
allow different rates for the different partitions and codon posi-
tions (Ronquist & Huelsenbeck, 2003; Nylander et al., 2004).
Four Metropolis-coupled Markov chain Monte Carlo chains
were run with incremental heating temperature 0.1 for 100 ×106
generations and sampled every 1000 generations, except the 12S
dataset, which was run for 50 ×106generations before conver-
gence occurred. The rst 10% of the generations were discarded
as ‘burn-in’, well after the chain likelihood values had become
stationary, and the posterior probability (PP) was estimated for
the remaining generations. The model t between an analysis
with monophyly constrained to conform with the yways within
each species was compared with the unconstrained model by dif-
ferences in log Bayes factors as implemented in  v.1.6
(http://tree.bio.ed.ac.uk/software/tracer/).
Results
The alignment of the 12s and 16s sequences revealed some
highly incompatible sections, which had to be readjusted man-
ually. For all loci (COI, 12S, and 16S), PPs were calculated
under the general time-reversible (GTR) model (Lanave et al.,
1984; Tavaré, 1986; Rodríguez et al., 1990), assuming rate vari-
ation across sites according to an inverse gamma distribution
with six rate categories for all models except COI third posi-
tions, in which a discrete gamma (G) distribution with six rate
categories was assumed (Yang, 1994). Results of the BI anal-
ysis of the combined and COI datasets are shown in Figs 1
and 2, respectively. Results from the analyses of the smaller 12S
and 16S datasets are shown in Figures S1 and S2, respectively.
Uncorrected p-distances within the Esthiopteridae are shown in
Table 3, and distances within Carduiceps are shown in Table 4.
Uncorrected p-distances within each genus are similar to those
reported from other groups (summarized in Gustafsson & Ols-
son, 2012a). Uncorrected p-distances within each Carduiceps
species are between 0.0% and 1.2%, which is also similar to that
observed in other louse genera (Gustafsson & Olsson, 2012a).
The matrices used for this study can be found at http://purl.org/
phylo/treebase/phylows/study/TB2:S20287.
Inuence of yways
All four included species of Carduiceps are monophyletic in
all analyses, typically with high support (Figs 1, 2; Figures
S1, S2). Moreover, none of the Carduiceps species samples
from more than one host yway unambiguously separated
into distinct clades comprising the material from each yway.
Comparisons between unconstrained trees and trees constrained
to conform to the yways resulted in much lower log Bayes
© 2017 The Royal Entomological Society, Systematic Entomology,42, 509– 522

514 D. R. Gustafsson and U. Olsson
141 Columbicola columbae – ex Columba livia domestica
375 Columbicola bacillus – ex Streptopelia decaocto
DQ314505 Aquanirmus rollandii– ex Rollandia rollandi
950 Aquanirmus sp– ex Tachybaptus novaehollandiae
AY314808 Aquanirmus sp– ex Poliocephalus poliocephalus
AY314810 Craspedonirmus immer– ex Gavia immer
AF396545 Ardeicola geronticorum– ex Geronticus calvus
AF545677 Ardeicola ardeae– ex Ardea cinerea
AF380005 Fulicoffula longipila– ex Fulica americana
AF545701 Fulicoffula heliornis– ex Heliornis fulica
AY314817 Ibidoecus bisignatus– ex Plegadis chichi
493 Anaticola crassicornis– ex Anas strepera
464 Anaticola rheinwaldi– ex Branta bernicla
462 Anatoecus sp– ex Branta bernicla
350 Degeeriella nisus– ex Accipiter nisus
471 Degeeriella fulva– ex Buteo lagopus
334 Rhynonirmus scolopacis– ex Gallinago gallinago
276 Quadraceps auratus– ex Haematopus ostralegus
215 Saemundssonia lockleyi– ex Sterna paradisaea
216 Saemundssonia sternae– ex Sterna hirundo
69 Quadraceps obtusus– ex Tringa totanus
20.0
0,9
0,73
1
1
0,64
1
1
0,47
0,42
1
0,87
1
0,72
0,56
1
1
0,99
1
1
0,67
0,99
1
1
1
1
816 Carduiceps zonarius – ex Cal. rucollis EAs
1482 Carduiceps zonarius – ex Cal. minutilla PAm
1486 Carduiceps zonarius – ex Cal. mauri PAm
1546 Carduiceps zonarius – ex Cal. pusillus PAm
170 Carduiceps zonarius – ex Cal. ferruginea EAtl
287 Carduiceps zonarius – ex Cal. canutus canutus EAtl
345 Carduiceps zonarius – ex Cal. minuta EAtl
395 Carduiceps sp – ex Lymnocryptes minimus EAtl
808 Carduiceps zonarius – ex Cal. alba EAs
954 Carduiceps zonarius – ex Cal. acuminata EAs
19 Carduiceps meinertzhageni – ex Cal. alpina alpina EAtl
224 Carduiceps meinertzhageni – ex Cal. alpina schinzii EAtl
775 Carduiceps meinertzhageni – ex Cal. alpina sakhalina EAs
515 Carduiceps scalaris – ex Philomachus pugnax EAtl
858 Carduiceps fulvofasciatus – ex Xenus cinereus EAs
eadiretpo
i
htsE sensu 3
6
91 rel
h
ciE
Nearctic – West Palearctic – East Palearctic –
Pacic Americas Flyway East Atlantic Flyway East Asian/Australasian Flyway
0,27
0,75
0,39
1
0,2
0,34
0,79
0,58
0,42
1
11
1
0,99
W
PAm EAtl EAs
Fig. 1. Majority rule (50%) consensus tree of Esthiopteridae sensu Eichler (1963) based on the combined cytochrome coxidase subunit I (COI), 12S
and 16S dataset, inferred by Bayesian inference under the GTR +I+G model, except for third codon positions of COI, which used the GTR+G model.
Posterior probabilities (≥50%) are indicated at the nodes. The specic identity of the host is given directly after the name of each individual louse sample.
Numbers before names are sample identiers (see Table 2). Abbreviations after taxon names correspond to yway afliation (PAm, Pacic Americas
Flyway; EAtl, East Atlantic Flyway; EAs, East Asian/Australasian Flyway), as outlined in the inset, where arrows denote approximate collection
localities for migrating birds, and ‘W’ approximate collection localities for wintering birds. [Colour gure can be viewed at wileyonlinelibrary.com].
© 2017 The Royal Entomological Society, Systematic Entomology,42, 509– 522

Distribution patterns of Carduiceps 515
0.1
1508 Carduiceps zonarius – ex Cal. mauri PAm
816 Carduiceps zonarius – ex Cal. rucollis EAs
1539 Carduiceps zonarius – ex Cal. minutilla PAm
0.77/–
1480 Carduiceps zonarius – ex Cal. mauri PAm
1607 Carduiceps zonarius – ex Cal. pusillus PAm
1561 Carduiceps zonarius – ex Cal. pusillus PAm
1546 Carduiceps zonarius – ex Cal. pusillus PAm
1495 Carduiceps zonarius – ex Cal. minutilla PAm
1482 Carduiceps zonarius – ex Cal. minutilla PAm
1486 Carduiceps zonarius – ex Cal. mauri PAm
0.80/72
1502 Carduiceps zonarius – ex Cal. mauri PAm
843 Carduiceps zonarius – ex Cal. rucollis EAs
0.98/68
287 Carduiceps zonarius – ex Cal. canutus canutus EAtl
0.73/–
0.61/–
954 Carduiceps zonarius – ex Cal. acuminata EAs
395 Carduiceps sp – ex Lymnocryptes minimus EAtl
817 Carduiceps zonarius – ex Cal. rucollis EAs
845 Carduiceps zonarius – ex Cal. ferruginea EAs
170 Carduiceps zonarius – ex Cal. ferruginea EAtl
824 Carduiceps zonarius – ex Cal. canutus rogersi EAs
796 Carduiceps zonarius – ex Cal. canutus rogersi EAs
808 Carduiceps zonarius – ex Cal. alba EAs
807 Carduiceps zonarius – ex Cal. alba EAs
956 Carduiceps zonarius – ex Cal. acuminata EAs
10 1 Carduiceps meinertzhageni – ex Cal. alpina alpina EAtl
775 2 Carduiceps meinertzhageni – ex Cal. alpina sakhalina EAs
775 1 Carduiceps meinertzhageni – ex Cal. alpina sakhalina EAs
224 2 Carduiceps meinertzhageni – ex Cal. alpina schinzii EAtl
224 1 Carduiceps meinertzhageni – ex Cal. alpina schinzii EAtl
19 2 Carduiceps meinertzhageni – ex Cal. alpina alpina EAtl
19 1 Carduiceps meinertzhageni – ex Cal. alpina alpina EAtl
0.96/50
515 1 Carduiceps scalaris – ex Philomachus pugnax EAtl
515 2 Carduiceps scalaris – ex Philomachus pugnax EAtl
0.81/–
321 Carduiceps scalaris – ex Philomachus pugnax EAtl
*/70
858 Carduiceps fulvofasciatus – ex Xenus cinereus EAs
860 Carduiceps fulvofasciatus – ex Xenus cinereus EAs
*/68
950 Aquanirmus sp– ex Tachybaptus novaehollandiae
DQ314505 Aquanirmus rollandii– ex Rollandia rollandi
0.67/64
AY314808 Aquanirmus sp– ex Poliocephalus poliocephalus
*/99
462 Anatoecus sp– ex Branta bernicla
0.98/–
493 Anaticola crassicornis– ex Anas strepera
464 Anaticola rheinwaldi– ex Branta bernicla
*/54
0.95/–
AF545677 Ardeicola ardeae– ex Ardea cinerea
AF396545 Ardeicola geronticorum– ex Geronticus calvus
*/–
AF380005 Fulicoffula longipila– ex Fulica americana
AF545701 Fulicoffula heliornis– ex Heliornis fulica
*/61
0.59/–
0.82/–
141 Columbicola columbae – ex Columba livia domestica
375 Columbicola bacillus – ex Streptopelia decaocto
*/86
AY314810 Craspedonirmus immer– ex Gavia immer
0.93/–
AY314817 Ibidoecus bisignatus– ex Plegadis chichi
*/–
350 Degeeriella nisus– ex Accipiter nisus
471 Degeeriella fulva– ex Buteo lagopus
0.87/68
334 Rhynonirmus scolopacis– ex Gallinago gallinago
*/90
*/76
215 Saemundssonia lockleyi– ex Sterna paradisaea
216 Saemundssonia sternae– ex Sterna hirundo
*/98
276 Quadraceps auratus– ex Haematopus ostralegus
0.58/–
0.99/77
69 Quadraceps obtusus– ex Tringa totanus
*/*
*/*
*/*
*/*
Nearctic – West Palearctic – East Palearctic –
Pacic Americas Flyway East Atlantic Flyway East Asian/Australasian Flyway
PAm EAtl EAs
eadiret
poihtsE sensu 3691 re
l
hciE
W
Fig. 2. Majority rule (50%) consensus tree of Esthiopteridae sensu Eichler (1963) based on mitochondrial cytochrome coxidase subunit I (COI)
sequences, inferred by Bayesian inference under the GTR +G+I model, except for third codon positions of COI, which used the GTR +G model.
Posterior probabilities (≥50%) are indicated at the nodes. Numbers before names are sample identiers (see Table 2). Flyway abbreviations at the end
of terminals are: PAm, Pacic Americas; EAtl, East Atlantic; EAs, East Asian/Australasian. [Colour gure can be viewed at wileyonlinelibrary.com].
© 2017 The Royal Entomological Society, Systematic Entomology,42, 509– 522

516 D. R. Gustafsson and U. Olsson
Tabl e 3. Uncorrected p-distances for cytochrome coxidase subunit I
(COI) within Esthiopteridae.
Ac Ae Aq Ar Ca Co Cr Fu Ib
Ac 19.0
Ae 23.5 –
Aq 23.9 23.4 14.4
Ar 24.0 24.0 24.2 18.5
Ca 25.3 27.0 28.6 25.4 10.7
Co 26.3 27.6 29.1 26.9 28.4 19.5
Cr 27.5 28.6 29.4 30.3 29.9 26.6 –
Fu 23.7 22.4 25.6 22.9 25.6 29.0 25.8 17.8
Ib 25.2 22.2 26.1 23.9 26.5 28.9 27.8 23.9 –
Ac,Anaticola;Ae,Anatoecus;Aq,Aquanirmus;Ar,Ardeicola;Ca,Car-
duiceps;Co,Columbicola;Cr,Craspedonirmus;Fu,Fulicoffula;Ib,
Ibidoecus. All numbers are expressed as percentages, with dashes rep-
resenting one-taxon clades within which no distances can be measured.
Highest and lowest between-genus distances have been bolded.
Tabl e 4. Uncorrected p-distances for the COI dataset within Cardui-
ceps.
C.
fulvofaciatus
C.
meinertzhageni
C.
scalaris
C.
zonarius
C. fulvofasciatus 0.5
C. meinertzhageni 21.8 0.0
C. scalaris 24.2 18.3 0.4
C. zonarius 24.3 16.0 18.0 1.2
All numbers expressed as percentages.
factors for the unconstrained tree (AICM difference 1503.333).
There is thus no clear support for either yway homogenization
or yway differentiation in Carduiceps.
Signicantly, Car. zonarius is monophyletic despite being
sampled from a large number of hosts from different yways,
and the samples show low genetic variation (Table 4). Cardui-
ceps zonarius contains some structure in most datasets; how-
ever, this structure is partially contradictory, often with short
branch lengths and low support (e.g. Fig. 1). In the COI, 16S and
combined datasets, there are tendencies for subdivisions of Car.
zonarius between material from the Nearctic and the Palaearctic.
However, the separation is not complete, as one Palaearctic indi-
vidual (from Cal. rucollis) is grouped with the Nearctic mate-
rial, and one Nearctic individual (from Cal. mauri) is grouped
with the Palaearctic material. The relationships amongst the four
species of Carduiceps also vary between datasets, and may be
heavily affected by missing data.
Eichler’s (1963) Esthiopteridae
Our analyses generally result in a basal polytomy for
Esthiopteridae (sensu Eichler, 1963) (e.g. Fig. 2), with lit-
tle resolution apart from species in the same genera being
grouped together. However, in all analyses, both Carduiceps
and Esthiopteridae sensu Eichler (1963) are monophyletic with
high PPs (PP =1.00). Carduiceps is monophyletic with high
support (PP =1.00) in all analyses. The combined analysis
(Fig. 1) retrieves monophyletic Anaticola (PP =1.00), Aquanir-
mus (PP =1.00), Ardeicola (PP =1.00) and Columbicola
(PP =1.00). The two duck louse genera, Anatoecus and
Anaticola, are grouped together with the grebe louse genus
Aquanirmus in all datasets where all three genera were rep-
resented (PP =1.00 in the combined and 12S datasets, but
PP =0.95 in the COI dataset).
The 12S dataset suggests that Columbicola and Craspedonir-
mus may be the closest relatives of Carduiceps (PP =0.97);
however, this relationship is not recovered with any support
in any of the other datasets. One species of Craspedonirmus
is known from shorebirds, whereas Columbicola is specic
to pigeons and doves (Price et al., 2003). While there is mor-
phological support for a relationship between these three
genera (see Discussion), the lack of support for this group in
the concatenated dataset (PP =0.47) and the COI dataset (in
unresolved polytomy) indicates that the relationship may be
spurious. Notably, Craspedonirmus and Columbicola were also
placed together in the COI dataset (PP =0.93).
Discussion
Taxonomic and systematic issues within Carduiceps
The phylogeny reconstructed for Carduiceps based on three
mitochondrial genes corresponds perfectly with the current
taxonomy of the genus (Timmermann, 1954; Table 5), and
no changes in the taxonomy of Carduiceps are implied by
this study. As several of the Carduiceps species treated by
Timmermann (1954) were not included in these analyses, his
division of the genus into three species groups cannot be tested
presently. The four included species of Carduiceps are all
reciprocally monophyletic (Figs 1, 2; Figures S1, S2), but apart
from the placement of Car. fulvofasciatus as sister to the three
other species, there is no supported structure among Carduiceps
in the combined dataset (Fig. 1). Many of the samples included
here were only successfully sequenced for one or two of the
three genes. This has probably affected the resolution of the
trees, especially the 12S and 16S datasets, which contain the
least amount of specimens.
Inuence of yways on host distribution of Carduiceps
We recovered no support for either yway homogenization or
yway differentiation in Carduiceps.Carduiceps scalaris and
Car. fulvofasciatus are both restricted to a single host species,
and do not occur on other hosts species samples in the same
localities at the same time (data not shown). Xenus cinereus,the
host of Car. fulvofasciatus, also occur salong the West Palearctic
yway, but no samples were obtained from this host population,
and its potential division into populations following different
yways could therefore not be tested.
Carduiceps meinertzhageni was sampled from three morpho-
logically distinct host subspecies that migrate along two differ-
ent yways (Wenink et al., 1996; Message & Taylor, 2005; but
see Marthinsen et al., 2007). Despite this broad sampling range,
© 2017 The Royal Entomological Society, Systematic Entomology,42, 509– 522

Distribution patterns of Carduiceps 517
Tabl e 5. Taxonomy and host relationships of Carduiceps.
Louse name Host name Common name
Carduiceps cingulatus (Denny, 1842) Limnodromus griseus (Gmelin, 1789) Short-billed Dowitcher
Limnodromus scolopaceus (Say, 1822) Long-billed Dowitcher
Limosa limosa (Linnaeus, 1758) Black-tailed Godwit
Carduiceps clayae Timmermann, 1954 Limosa fedoa (Linnaeus, 1758) Marbled Godwit
Carduiceps fulvofasciatus (Grube, 1851) Xenus cinereus (Güldenstädt, 1775) Terek Sandpiper
Carduiceps lapponicus Emerson, 1953 Limosa lapponica (Linnaeus, 1758) Bar-tailed Godwit
Carduiceps meinertzhageni Timmermann, 1954 Calidris alpina alpina (Linnaeus, 1758) Dunlin
Calidris alpina sakhalina (Vieillot, 1816)* Dunlin
Calidris alpina schinzii (Brehm & Schilling, 1822)* Dunlin
Calidris maritima (Brünnich, 1764) Purple Sandpiper
Calidris ptilocnemis (Coues, 1873) Rock Sandpiper
Carduiceps scalaris (Piaget, 1880) Calidris pugnax (Linnaeus, 1758) Ruff
Carduiceps subscalaris (Piaget, 1880) Phalaropus lobatus (Linnaeus, 1758) Red-necked Phalarope
Carduiceps zonarius (Nitzsch [in Giebel], 1866) Calidris acuminata (Horseld, 1821) Sharp-tailed Sandpiper
Calidris alba (Pallas, 1764) Sanderling
Calidris bairdii (Coues, 1861) Baird’s Sandpiper
Calidris canutus canutus (Linnaeus, 1758) Red Knot
Calidris canutus rogersi (Mathews, 1913)* Red Knot
Calidris ferruginea (Pontoppidan, 1763) Curlew Sandpiper
Calidris fuscicollis (Vieillot, 1819) White-rumped Sandpiper
Calidris mauri (Cabanis, 1857) Western Sandpiper
Calidris himantopus (Bonaparte, 1826) Stilt Sandpiper
Calidris melanotos (Vieillot, 1819) Pectoral Sandpiper
Calidris minuta (Leisler, 1812) Little Stint
Calidris minutilla (Vieillot, 1819) Least Sandpiper
Calidris pusilla (Linnaeus, 1766) Semipalmated Sandpiper
Calidris pygmaeus (Linnaeus, 1758) Spoon-billed Sandpiper
Calidris rucollis (Pallas, 1776) Red-necked Stint
Calidris subminuta (Middendorff, 1853) Long-toed Stint
Calidris subrucollis (Vieillot, 1819) Buff-breasted Sandpiper
Calidris temminckii (Leisler, 1812) Temminck’s Sandpiper
Lymnocryptes minimus (Brünnich, 1764)* Jack Snipe
Taxa marked with an asterisk (*) are a new host record in this paper. All other host relationships follow Price etal. (2003).
the sequences from these lice are genetically identical (Table 4),
and there is no division between louse populations sampled from
the different yways. Moreover, we have found no specimens of
Car. meinertzhageni on other host species sampled at the same
localities at the same time (data not shown).
The homogeneity of the Car. meinertzhageni material across
host subspecies may be an effect of recent divergence in these
host subspecies (Wenink et al., 1996), with differentiation in
Carduiceps being slower than in their hosts. This is surprising,
as base substitution rates are generally much faster in lice than
in their host animals (Johnson et al., 2003a). Alternatively,
as different host subspecies may be found in the same ocks
during migration and wintering (e.g. Wenink & Baker, 1996),
the occurrence of the same Carduiceps haplotype on birds
sampled from different subspecies may indicate that the lice
are capable of dispersal to other subspecies of Cal. alpina,
but not to other Calidris species. No American populations of
Cal. alpina were sampled, so it is impossible to tell whether
there is a split between Old and New World populations of Car.
meinertzhageni. In addition, two recorded hosts of Car. mein-
ertzhageni (Price et al., 2003) with more limited distributions
(Message & Taylor, 2005), Cal. maritima and Cal. ptilocnemis,
were not sampled. Johnson et al. (2003b) suggested that a very
small amount of gene ow, even through an intermediary host,
may be enough for speciation to fail even in allopatric species.
Small numbers of sandpipers from one yway regularly visit
other yways, which could potentially be sufcient to stie
speciation. In either case, among the host species studied,
dispersing individuals of Car. meinertzhageni only seem to
have become successfully established on Cal. alpina.
In the Car. zonarius material there seems to be a slight differ-
ence between haplotypes collected from the Pacic Americas
yway and those collected from the two Palaearctic yways.
However, there is no support for a geographic divergence in
the phylogenetic analyses, and the genetic distances within this
species are comparable to those of the other three Carduiceps
species, and similar to those reported for other chewing lice
(Gustafsson & Olsson 2012a). In two cases, Carduiceps zonar-
ius was sampled from the same host species along different y-
ways (Cal. canutus and Cal. ferruginea). These samples show
no evidence of yway differentiation between the different y-
ways. In Car. zonarius, the capacity for establishment on differ-
ent host species seems to be higher than in Car. meinertzhageni,
but intense sampling efforts have not recovered Car. zonarius on
© 2017 The Royal Entomological Society, Systematic Entomology,42, 509– 522

518 D. R. Gustafsson and U. Olsson
any of the hosts of Car. fulvofasciatus,Car. meinertzhageni or
Car. scalaris (data not shown).
Both Car. meinertzhageni and Car. zonarius thus exhibit host
distribution patterns that are structured more by host species than
by host biogeography. Palaeoyways (Kraaijeveld & Nieboer,
2000; Buehler et al., 2006) could perhaps explain some of
the patterns, as the present distribution of Carduiceps on the
calidrines may have been established before or during the last
ice age when the hosts may have followed different yways than
they presently do.
Possible limitations for host range in Carduiceps
As the hosts of all four species of Carduiceps often occur in
mixed ocks in wintering sites, it is difcult to explain why each
host species is only parasitized by a single species of Cardui-
ceps,andwhyCar. zonarius has not been found on the hosts of
the other species of Carduiceps. The known hosts of Car. mein-
ertzhageni form a monophyletic clade within the sandpipers,
but the hosts of Car. zonarius do not (Gibson & Baker, 2012).
There is some evidence that wing lice generally cannot
successfully colonize new hosts that are much larger or smaller
(Tompkins et al., 1999; Johnson et al., 2005; Bush & Clayton,
2006). Whether this is generally true for generalist lice, such
as Carduiceps, is unknown. The size range of the hosts of
Carduiceps is large, but Car. zonarius occurs on both the
smallest sampled hosts (Cal. rucollis and Cal. minutilla)and
the largest sampled hosts (Cal. canutus). Calidris alpina,the
host of Car. meinertzhageni, falls in between these extremes and
is similar in size to several of the hosts of Car. zonarius (Message
& Taylor, 2005). Host size alone may therefore not be a factor
in the host distribution of Carduiceps lice.
An alternative explanation may be host pigmentation differ-
ences (Bush et al., 2010). All the hosts of Car. meinertzhageni
(including unsampled hosts; Price et al., 2003) are either
black-bellied or have mainly dark-grey feathers in at least one
plumage (Message & Taylor, 2005), whereas the hosts of Car.
zonarius are generally white-bellied in all plumages. Lice of the
genus Machaerilaemus have been found to prefer white parts
of feathers over black parts (Kose & Møller, 1999; Kose et al.,
1999), suggesting that melanin in bird feathers may deter lice. If
Car. meinertzhageni has a greater ability to digest melanin, this
could give it an advantage over host-switching Car. zonarius,
and could explain why Car. meinertzhageni occurs only on
black-bellied or dark-grey hosts. However, Cal. tenuirostris is
densely black-spotted, but is nevertheless parasitized by Car.
zonarius. Moreover, all three hosts of Car. meinertzhageni also
have areas of white body feathers. Bush et al. (2006) found
no correlation between the amount of melanin in feathers and
the abundance of pigeon lice (Columbicola and Campanu-
lotes), suggesting that the distribution of Car. meinertzhageni
on black-bellied or dark-grey hosts may be unrelated to host
pigmentation patterns.
The most curious aspect of Carduiceps distribution lies in
comparison with the Lunaceps wing lice of the same hosts. In
pigeons and doves, wing lice are less species-specic and less
geographically structured than body lice (Johnson et al., 2002a;
Clayton & Johnson, 2003), which could be related to the greater
ability of wing lice to disperse by phoresy on hippoboscid
ies (Keirans, 1975; Harbison et al., 2008, 2009; Bartlow et al.,
2016). Similar patterns were found in seabird lice (Page et al.,
2004). Even in the absence of a host biogeographic structuring
according to host yways, Carduiceps would therefore still
be expected to be more species-specic than Lunaceps.No
cases of phoresy involving shorebird lice are known (Keirans,
1975; Bartlow et al., 2016), but Lunaceps wing lice would be
better placed on its host, topologically, to take advantage of
opportunities for spread to new hosts than Carduiceps body lice,
even in the absence of phoresy. Despite this, Carduiceps is both
much less geographically structured and less host-specic than
Lunaceps (Gustafsson & Olsson, 2012a). This implies that some
other set of dispersal mechanisms may be available to shorebird
lice than to pigeon lice. Continued studies on shorebird louse
genera such as Saemundssonia and Quadraceps may be most
instructive in this regard.
Esthiopteridae sensu Eichler, 1963
While neither Cruickshank et al. (2001) nor Johnson et al.
(2006) recovered monophyly of the Esthiopteridae, it is sug-
gested to be monophyletic in all of our datasets (PP =1.00;
Figs 1, 2; Figures S1, S2). However, relationships within
Esthiopteridae remain obscure, and relationships above the
genus level generally have no support in either of our analyses.
As only a few species each of the proposed esthiopterids genera
were included, few conclusions can be drawn.
Aquanirmus has been grouped quite consistently with the
duck lice Anaticola and Anatoecus in previous molecular studies
(Cruickshank et al., 2001; Johnson et al., 2006), but with Ibi-
doecus in morphological studies (Smith, 2001). In this study,
Aquanirmus groups with the duck lice Anaticola and Anatoecus
in all datasets where all three genera are included.
Ardeicola has a chequered history of having been grouped with
the duck lice (Johnson et al., 2003a), the Philoceanus complex
(Smith, 2001), Mulcticola (placed in Rallicolidae by Eichler,
1963; Cruickshank et al., 2001) or even the Amblycera (Cruick-
shank et al., 2001). In the most inclusive dataset (morphol-
ogy +genetic data) of Smith et al. (2004), Ardeicola appears to
have no close relatives, but when molecular data are considered
alone, they either group with Falcolipeurus (parsimony), with
the mammal lice (likelihood), or are placed as sister to most of
the other genera (Bayesian). This study does not resolve the rela-
tionships of Ardeicola, except that all datasets where this genus
is represented place it inside Esthiopteridae. This placement may
be supported by morphology, as aspects of the preantennal area
and the male genitalia are similar to those seen in other genera
Eichler (1963) placed in Esthiopteridae, but this family has never
been satisfactorily circumscribed morphologically.
Columbicola has been separated from other esthiopterids
in many previous studies (Cruickshank et al., 2001; Smith,
2001; Johnson et al., 2003a; Smith et al., 2004), but has
been placed as sister to Craspedonirmus (Smith et al., 2004,
© 2017 The Royal Entomological Society, Systematic Entomology,42, 509– 522

Distribution patterns of Carduiceps 519
g. 6a, b) and close to Fulicoffula (Johnson & Whiting, 2002) or
Anatoecus +Neophilopterus +Fulicoffula +Cirrophthirius [the
latter placed in Rallicolidae by Eichler (1963)] (Barker et al.,
2003). None of these studies have included any Carduiceps,and
the sister-group relationship between Columbicola and Craspe-
donirmus suggested in the combined dataset, and the close
relationship between these two and Carduiceps suggested by
the 12S dataset are novel. Columbicola is restricted to pigeons
and doves, Craspedonirmus to loons and auks, and Carduiceps
to sandpipers and allies. These host groups do not form a mono-
phyletic group together (e.g. Hackett et al., 2008), suggesting
that these relationships are either spurious or not explainable
through a simple application of Fahrenholz’s rule (i.e. that louse
relationships should mirror host relationships; Klassen, 1982).
Carduiceps,Craspedonirmus and Columbicola are not very
similar in gross morphology. However, all three genera share at
least two morphological characters: the presence of an arched,
transversally continuous preantennal carina arising at the pre-
antennal nodi and the presence of a transversally continuous
dorsal postantennal suture immediately posterior to this carina.
In all three genera, the suture is extended posteriorly across at
least part of each temple, and the post-nodal seta (sensu Clay,
1951) and sensilla 2–3 (sensu Valim & Silveira, 2014) are gen-
erally associated with this suture. This head structure is, to our
knowledge, not known from any other genus of ischnoceran lice.
However, a similar, medianly interrupted carina is found in some
members of the Quadraceps complex (e.g. Quadraceps semi-
ssa; see Timmermann, 1953).
Leaving aside Columbicola and Craspedonirmus,Carduiceps
appears to have no close relatives and is not related to any
other louse genus on the shorebirds (D. Gustafsson, unpub-
lished data), but seems to represent a separate, very localized,
colonization of the Scolopacidae. However, the louse genera
included in this study were selected based on their placement
in Esthiopteridae by Eichler (1963), and close relatives of
Carduiceps outside this group may well have been overlooked
in the process of outgroup selection.
In short, the relationships within Eichler’s (1963) Esthiopteri-
dae are in need of further clarication, requiring greater sam-
pling of genera other than Columbicola and Carduiceps,and
the use of additional unlinked molecular markers, particularly
nuclear markers, as well as a morphological revision. In addi-
tion, several of the genera included here were represented
only in the COI analysis, as data were not available for the
other two markers used. Suitable sister groups should also be
identied and sampled, to test the phylogenetic position and
possible sister-group relationship of Carduiceps and Columbi-
cola +Craspedonirmus. If this sister-group relationship is found
to be an artifact of sampling or analysis, on present knowledge
this leaves Carduiceps with no known close relatives.
Summary
There is no evidence of either yway homogenization or
yway differentiation in Carduiceps. Two host species were
sampled from more than one yway, and in both cases there
were no signicant differences between louse material from
different yways. The large host range of Car. zonarius may be
the result of yway homogenization in the past, but if so, this
homogenization is incomplete, as the hosts of the other three
Carduiceps species sampled migrate along the same yways and
winter in the same areas. Possibly, other features of the hosts’
ecology, such as plumage patterns, may explain the structuring
of Carduiceps.
Eichler’s (1963) proposed Esthiopteridae may be mono-
phyletic, as indicated by high Bayesian support across all
datasets. However, resolution within this group is poor. One
reason may be that appropriate outgroups or sister groups may
be lacking, as the phylogeny of lice is incompletely known.
Another reason may be that the absence of nuclear markers in
this analysis, as well as the few available sequences for most of
the genera in this group limit our present understanding of the
evolution of this group. In the analysis of the 12S dataset, the
dove louse genus Columbicola and the loon and auk louse genus
Craspedonirmus are suggested as the closest relatives to Cardui-
ceps. This relationship does not receive any support in the com-
bined analysis, and may be spurious. Nevertheless, the genus
Columbicola is a widely used model group for many aspects
of louse and parasite evolution, and this novel relationship with
Craspedonirmus and Carduiceps requires further study.
Supporting Information
Additional Supporting Information may be found in the online
version of this article under the DOI reference:
10.1111/syen.12227
Figure S1. Majority rule (50%) consensus tree of
Esthiopteridae sensu Eichler (1963) based on mitochon-
drial 12S sequences, inferred by Bayesian inference under
the GTR+G+I model. Posterior probabilities are indicated
at the nodes. Numbers before names are sample identiers
(see Table 2).
Figure S2. Majority rule (50%) consensus tree of
Esthiopteridae sensu Eichler (1963) based on mitochon-
drial 16S sequences, inferred by Bayesian inference under
the GTR +G+I model. Posterior probabilities are indicated
at the nodes. Numbers before names are sample identiers
(see Table 2).
Acknowledgements
The authors would like to thank the staff and volunteers
of Ottenby Bird Observatory; Hampus Lybeck and Emelie
Lindquist (University of Gothenburg); Darius Strasevicus (Ume
River Delta Bird Observatory); Yoshi Shigeta and the crew at
Tori-no-Umi, Japan; the staff and volunteers of the Yamashina
Institute for Ornithology; Clive Minton, Chris Hassell, Roz
Jessop and the organizers and participants of the Australasian
Wader Study Group’s expedition to North West Australia in
2008; and David Lank and his PhD students and volunteer
© 2017 The Royal Entomological Society, Systematic Entomology,42, 509– 522

520 D. R. Gustafsson and U. Olsson
assistants in Vancouver, particularly Samantha Franks, David
Hodgkins and Rachel Gardiner. We would also like to thank
Anna Ansebo (University of Gothenburg) for being invaluable
in so many ways. Funding for this work was provided by the
Swedish Taxonomy Initiative (36/07 1.4) and from the Wilhelm
and Martina Lundgrens Vetenskapsfond 1 (vet1-379/2008 and
vet1-415/2009). Neither of these had any hand in study design,
collection work, analysis or interpretation of data. This paper
represents contribution no. 295 in the Ottenby Bird Observa-
tory Scientic Report Series. Collection in Sweden was carried
out under the ethical approvals 171-2006 and 157-2010 (Jord-
bruksverket). Collection in Australia was carried out under reg-
ulation 17 licence SF006502 (Department of Environment and
Conservation, Western Australia), and exported under regulation
18 licence OS002459 (Department of Environment and Conser-
vation, Western Australia). Two anonymous reviewers provided
valuable comments, for which we are grateful.
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Accepted 6 December 2016
First published online 2 February 2017
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