Key and checklist of the bristletails (Microcoryphia)

Key and checklist of the bristletails (Microcoryphia) of
America north of Mexico
Mahew L. Bowser
May 9, 2012
1
Apology
Below is a dra checklist of and key to the jumping bristletails (Microcoryphia or Archaeognatha) of America north of Mexico based primarily on existing keys (Wygodzinsky and Schmidt, 1980; Sturm, 1983; Ferguson, 1990; Mendes, 1990; Sturm, 1991) and
descriptions (Silvestri, 1911; Allen, 1995; Sturm, 2001; Packauskas and Shofner, 2010).
I apologize for the paucity of figures and the sometimes ambiguous characters used.
I first constructed this key for my own use, but future dras should be increasingly
accessible. Please contact me at Matt_Bowser@fws.gov if you have questions or if
you find problems with the key.
e institutions below are referred to in the text.
CAS
California Academy of Sciences, San Francisco, California
IEA
Instituto di Entomologia Agraria, Portici/Napoli, Italy (Is this now
DEZA?)
KNWR Kenai National Wildlife Refuge, Soldotna, Alaska
PAS
Polish Academy of Sciences, Kracov, Poland
UAM
University of Alaska Museum of the North, Fairbanks, Alaska
USNM
U.S. National Museum of Natural History, Washington D.C.
UWBM Burke Museum of Natural History and Culture, Seale, Washington
2
Chelist
Family Mailidae
Subfamily Mailinae
Genus Mesomailis
Subgenus Mesomailis
1
Mesomailis leei Sturm, 1991
Distribution: USA: California (Sturm, 1991).
Type Material: holotype ♂, allotype ♀ and paratype ♂ and ♀ at CAS (Sturm, 1991).
Mesomailis nearctica Silvestri, 1911
Mixomailis remingtoni Paclt, 1972
Distribution: USA: Arizona (Mendes, 1992; Sturm, 1991), California (Silvestri, 1911;
Sturm, 1991; Baldo et al., 2010), Colorado (Silvestri, 1911), Nevada (Sturm, 1991; Baldo
et al., 2010), and Utah (Baldoetal2010, KNWR:Ento:8123).
Type Material: Type ♀ and paratype ♂ and ♀ at IEA (Sturm, 1991).
Mesomailis cf. nearctica sensu Baldo et al. (2010)
Distribution: USA: California, Nevada, and Utah (Baldo et al., 2010).
Mesomailis strenua (Silvestri, 1911)
Mailis strenua Silvestri, 1911
Pedetontus strenuus Smith, 1970
Distribution: USA: California (Silvestri, 1911).
Subgenus Raroilis
Mesomailis californica Sturm, 1991
Distribution: USA: California (Sturm, 1991).
Type Material: holotype ♂, allotype ♀, and paratype ♂ and ♀ at CAS (Sturm, 1991).
Mesomailis canadensis Sturm, 1991
Distribution: CANADA: British Columbia (Sturm, 1991). USA: Oregon (KNWR:Ento:8159).
Type Material: holotype ♂; allotype ♀; 9 ♂, 16 ♀, and 14 immature paratypes at USNM
(Sturm, 1991).
Genus Trigoniophthalmus
Trigoniophthalmus alternatus (Silvestri, 1904)
Mailis alternata Silvestri, 1904
Distribution: USA: New York (Silvestri, 1911; Wygodzinsky and Schmidt, 1980); Connecticut, Maryland, New Jersey, and Pennsylvania (Wygodzinsky and Schmidt, 1980).
Subfamily Petrobiinae
Genus Leptomailis
Leptomailis californica Sturm, 1991
Distribution: USA: California (Sturm, 1991). Type Material: type ♂, allotype ♀, and a
paratype ♂ at CAS (Sturm, 1991).
Genus Meximailis
2
Meximailis cokendolpheri Kaplin, 1994
Distribution: USA: New Mexico (Kaplin, 1994).
Genus Neomailis
Neomailis halophila Silvestri, 1911
Neomailis halophilus Silvestri, 1911
Distribution: USA: California (Silvestri, 1911; Benedei, 1973; Mendes, 1992).
Genus Pedetontoides
Pedetontoides atlanticus Mendes, 1981
Distribution: USA: North Carolina (Mendes, 1981).
Type Material: holotypes and paratypes at PAS except for two paratype ♀’s in the
collection of Luís Mendes (Luís Mendes, personal communication).
Pedetontoides cf. atlanticus
Distribution: CANADA: British Columbia (KNWR:Ento:8191)
Genus Pedetontus
Subgenus Pedetontus
Pedetontus californicus (Silvestri, 1911)
Distribution: USA: California (Silvestri, 1911; Mendes, 1992; Sturm, 2001).
Pedetontus saltator Wygodzinsky and Smidt, 1980
Distribution: USA: Connecticu, Massachuses, New Jersey, New York, and Pennsylvania (Wygodzinsky and Schmidt, 1980).
Pedetontus superior (Silvestri, 1911)
Distribution: USA: Oregon (Silvestri, 1911).
Pedetontus sii Sturm, 2001
Distribution: USA: California (Sturm, 2001).
Pedetontus yosemite Sturm, 2001
Distribution: USA: California (Sturm, 2001).
Subgenus Verhoeffilis
Pedetontus calcaratus (Silvestri, 1911)
Distribution: CANADA: British Columbia (Sturm, 1991; KNWR:Ento:8151, KNWR:Ento:8161).
USA: Colorado (Silvestri, 1911; Mendes, 1981).
Pedetontus gershneri Allen, 1995
Distribution: USA: Arkansas (Allen, 1995).
3
Pedetontus persquamosus (Silvestri, 1911)
Distribution: USA: California (Silvestri, 1911).
Pedetontus submutans (Silvestri, 1911)
Distribution: CANADA: British Columbia (KNWR:Ento:8158). USA: Alaska (UAM:Ento:87248),
Oregon (Silvestri, 1911, KNWR:Ento:8197), and Washington (Silvestri, 1911).
Genus Petridiobius
Subgenus Petridiobius
Petridiobius arcticus (Folsom, 1902)
Mailis arctica Folsom, 1902
Distribution: CANADA: British Colulmbia (KNWR:Ento:8195) USA: Alaska (Folsom,
1902; Sturm and Bowser, 2004, KNWR:Ento:7292).
Subgenus Pacltiobius
Petridiobius canadensis Sturm, 2001
Distribution: CANADA: British Columbia (Sturm, 2001).
Genus Petrobius
Petrobius brevistylis Carpenter, 1913
Petrobius canadensis Paclt, 1969
Distribution: CANADA: New Brunswick and Nova Scotia (Wygodzinsky and Schmidt,
1980). USA: Maine, Massachuses, New Hampshire, and Rhode Island (Wygodzinsky
and Schmidt, 1980)
Family Meinertellidae
Genus Hypomailoides
Hypomailoides forthaysi Paauskas and Shofner, 2010
Distribution: Kansas (Packauskas and Shofner, 2010).
Hypomailoides texanus Silvestri, 1911
Distribution: Texas (Silvestri, 1911).
Genus Mailinus
Mailinus aurantiacus Sött, 1897
Mailis aurantiacus Schö, 1897
Mailinus nevadensis Sweetman, 1937
Distribution: CANADA: British Columbia (Sturm and Bach de Roca, 1992; KNWR:Ento:8130).
USA: California (Silvestri, 1911; Sturm and Bach de Roca, 1992); Colorado (Silvestri,
1911); Arizona, Nevada, and Utah (Sturm and Bach de Roca, 1992).
4
Genus Mailoides
Mailoides banksi Silvestri, 1911
Distribution: USA: Arkansas (Allen, 1995), Maryland (Wygodzinsky and Schmidt,
1980), North Carolina (Mendes, 1981), and Virginia (Silvestri, 1911; Mendes, 1992).
Mailoides petauristes Wygodzinsky and Smidt, 1980
Distribution: USA: New Jersey (Wygodzinsky and Schmidt, 1980)
Genus Neomailellus
Neomailellus sp.
Distribution: USA: Georgia (Sturm, 1984; Wygodzinsky, 1967) and Florida (Wygodzinsky, 1967).
3
Key
1. All segments of antennae completely devoid of scales; median sclerites of urosternites reduced in size; each urosternite with not more than one pair of eversible vesicles (Figure 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Meinertellidae, 2
Scales present on at least basal antennal segments (Figure 2); median sclerites
of urosternites well developed; urosternites II-V each with one or two pairs of
eversible vesicles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Machilidae, 7
5
Figure 1: Photo of the head of a Meinertellid bristletail, probably Mailoides banksi,
Norfolk, Virginia, March 7, 2009. Photo by Sco Justis.
6
Figure 2: Macrophoto of the face of an unidentified bristletail (subfamily Petrobiinae) from Chimney Flat, Smith River National Recreation Area, Del Norte County,
California on June 11, 2008. Photo by Joyce Gross.
2. Coxal styli absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Coxal styli present, at least on legs III . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Lateral ocelli elongate, extending medially in front of the compound eyes
(Figure 3.A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Neomailellus
Lateral ocelli egg-shaped or elliptical, sublateral to the compound eyes
(Figure 3.B) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mailinus aurantiacus
A
B
Figure 3: Compound eyes and lateral ocelli of Meinertellidae, aer Silvestri (1911).
A. Neomailellus mexicanus. B. Mailinus aurantiacus.
4. Coxa of legs II and III with styli . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mailoides, 6
Coxa of legs III only with styli . . . . . . . . . . . . . . . . . . . . . . . . . . Hypomailodes, 5
7
5. Labial palpi of males with a large capitate process, its apex covered with distinct spines occurring proximally on the anterior face of the second segment
of the labial palpus, with only a few scaered, short spines near the base of the
capitate process. Females with dark pigment markings on at least the coxa of
legs I. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hypomailodes texanus
Process of labial palpi of males much more triangular, lacking spines on its
apex, with an oval cluster of longer spines on a raised mound near the base of
the process. Females without dark pigment markings on coxae. . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hypomailodes forthaysi
See Packauskas and Shofner (2010) for further diagnostic characters of H. forthaysi.
6. Clypeus predominantly light colored, with faint central longitudinal spot. Maxillary palp with segments III-V extensively darkened; second segment with one
pigment spot; fourth segment of maxillary palp very short and stout, three
times as long as wide. Coxa and femur of forelegs with very small pigment
spots, tarsus of third pair of legs uniformly darkened; basal tarsal segment of
legs I not darker than the others; anterior gonapophyses with approximately
45 divisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mailoides petauristes
Clypeus light colored along middle, broadly margined with dark pigment. Segments III-V of maxillary palps with dark pigment forming narrow, dark rings;
second segment of palp with two spots; fourth segment of maxillary palp slender, about six times as long as wide. Coxa and femur of forelegs with large
pigment spots; third pair of legs with first tarsal segment conspicuously darkened. Anterior gonapophyses with approximately 55 divisions . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mailoides banksi
7. Scales present on antennal flagellum . . . . . . . . . . . . . . . . . . . . . . . . . Machilinae, 8
Antennal flagellum devoid of scales . . . . . . . . . . . . . . . . . . . . . . . . . Petrobiinae, 15
8. Lateral ocelli small, tear-dropped shaped, submedial . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Trigoniophthalmus alternatus
Lateral ocelli sole-shaped, extending laterally close to or beyond the lateral
margin of the compound eyes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mesomailis, 9
9. Coxal stylets on midleg present . . . . . . . . . . . . . . . . . . . . . subgenus Raroilis, 10
Coxal stylets on midleg absent . . . . . . . . . . . . . . . . . . . subgenus Mesomailis, 14
Males of Mesomailis strenua, known from Shasta Springs, California, are unknown.
Females should key out with Mesomailis leei, but M. strenua has longer spines on
the ovipositor. See Silvestri (1911) and Sturm (1991).
10. At least one pair of coxal stylets of males modified, paddle-shaped (Figures 4, 5)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
All coxal stylets of males normal, acute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
8
Figure 4: Coxal stylet of midleg of a Mesomailis ♂ specimen from Osoyoos, British
Columbia (KNWR:Ento:8275).
11. Coxal stylet of hindleg of males normal, acute . . . . . . . . . . . Mesomailis sp. A
Coxal stylet of hindleg of males modified, at least somewhat broadened apically
12
I have seen specimens I am here calling Mesomailis sp. A from Osoyoos, British
Columbia (KNWR:Ento:8275).
12. Coxal stylet of midleg of males modified, broadened with darkly pigmented,
taered edges distally. (Figure 5). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mesomailis sp. B
Coxal stylet of midleg of males normal, acute . . . . . . . . . . . . Mesomailis sp. C
I have seen a specimen keying here to Mesomailis sp. B from Hells Canyon National
Recreation Area, Oregon (KNWR:Ento:8120). I have seen a specimen keying here to
Mesomailis sp. C from Asotin County, Washington (UWBM)
Figure 5: Sketch of coxal stylet III of a UWBM specimen from Captain John Rapids,
Asotin County, Washington.
13. Sensory field on femora I of male centrally with fringed tubercles; gonapophyses IX of female with very long setae on the proximal half, some of which are
distinctly longer than the width of the gonapophyses . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mesomailis canadensis
9
Sensory field on femora I of male without fringed tubercles; hairs on proximal
half of gonapophyses IX at most as long as width of the gonapophyses . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mesomailis californica
14. Tips of coxal stylets III of male represented by a knob-like structure; parameres
VIII absent; terminal spines of gonapophyses IX extremely small, not projecting beyond the distal end of the gonapophyses . . . . . . . Mesomailis nearctica
Tips of coxal stylets III of male of normal structure; parameres VIII highly reduced with at most 3 divisions; terminal spines of gonapophyses IX very small,
but projecting slightly beyond the distal end of the gonapophyses . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mesomailis leei
An additional, undescribed species similar to M. nearctica was partially described and
figured by Baldo et al. (2010).
15. 1 + 1 eversible vesicles only . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2 + 2 eversible vesicles on at least some abdominal segments . . . . . . . . . . . . . 17
16. Lateral ocelli of typical size or somewhat smaller, transverse, narrow (Figure 6).
Distal chains of the antennae with 8-10 subarticles . . . . Neomailis halophila
Lateral ocelli large, triangular to oval. Distal chains of the antennae with no
more than 8 subarticles. . . . . . . . . . . . . . . . . . . . . . . . . . . . Leptomailis californica
See Sturm (1991) for a more thorough comparison of Neomailis and Leptomailis.
Figure 6: Compound eyes and lateral ocelli of Neomailis halophila, aer Silvestri
(1911).
17. Lateral ocelli transverse, subelliptical, pear-shaped, or slightly sole-shaped, attaining only the apex of the ante-ocular sublateral area (Figure 7); paramera
restricted to the IXth segment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Petridiobius
Lateral ocelli sole-shaped, aaining the frontal ante-ocular area (Figure 10);
paramera variable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Petridiobius and its relationship with Pedetontus are troublesome at present. Most specimens will be keyed cleanly by these couplets because the lateral ocelli of Pedetontus
species generally are longer and usually do extend into the pigmented frontal anteocular area while the lateral ocelli of Petridiobius are restricted to the ante-ocular sublateral area; however there are specimens which I think might be Pedetontus, subgenus
Pedetontus that could key either way.
Also, the current descriptions of Petridiobius are confusing. I am forming an opinion
that all Petridiobius from coastal Alaska and British Columbia should be called Petridiobius arcticus and that Petridiobius canadensis may be a junior synonym of this species.
I think that Paclt’s (1970) redescription of Petridiobius arcticus is misleading. All specimens of Petridiobius that I have seen from the Aleutians to southern British Columbia
have had 2 + 2 eversible vesicles on abdominal segments II-VI.
10
Figure 7: Face of Petridiobius arcticus specimen from Sitka, Alaska (UAM:Ento:87253).
18. Paramera annulated, present on the VIIIth and IXth segments. Ovipositor
without interlocking, spine-like setae, though terminal spine-like setae may
be present. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Paramera annulated or entire, restricted to the IXth segment. Ovipositor usually without interlocking, spine-like setae, but such setae present in Pedetontus
calcaratus (Figure 9.B-C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
19. Abdominal sternites wide, obtuse. Apical spine of the abdominal stylets short
and stout. Foreleg of male modified. Female ovipositor apically with 2-4 stout,
fossorial setae. Lateral ocelli widest laterally, without a constriction in their
middles (as in Figure 6). . . . . . . . . . . . . . . . . . . . . . . . . Meximailis cokendolpheri
Abdominal sternites smaller, acute. Apical spine of the abdominal stylets long
and stout. Foreleg of male not modified. Female ovipositor lacking stout setae.
Lateral ocelli widest medially, with a pronounced constriction in their middles
making them sole-shaped (as in Figure 10.C). . . . . . . . . Pedetontoides atlanticus
I have seen specimens that appear to be nearly identical to Pedetontoides atlanticus from
British Columbia (e.g., KNWR:Ento:8191); however, the distal segments of the labial
palpi of males of the British Columbia specimens are more conical than in the corresponding illustration of male palpi of P. atlanticus (Fig. 6 in Mendes, 1981)
20. Molar area of mandible undentated or with 1-2 inconspicuous teeth; paramera
short and entire (unsegmented), the penis long and robust. Male genitalia partially exposed, not completely covered by the IXth coxitesPetrobius brevistylis
Molar area of mandible with four well-developed teeth (sometimes wearing
down with age); paramera clearly pseudosegmented, the penis typical; male
genitalia completely covered by the IXth coxites . . . . . . . . . . . . . . Pedetontus, 21
21. 2 + 2 eversible vesicles on abdominal coxites II-VI . . . subgenus Pedetontus, 22
2 + 2 eversible vesicles on abdominal coxites II-V only . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . subgenus Verhoeffilis, 26
22. Lateral ocelli close together (separated by 0.08 mm or less); extremely soleshaped (i.e., with a strong constriction in the middle) (Figure 8.C,D) . . . . . . . 23
Lateral ocelli separated by a greater distance; form variable (Figure 8.A,B) . 24
11
A
B
C
D
Figure 8: Compound eyes, lateral ocelli, and faces of Pedetontus (Pedetontus) species.
A. Pedetontus californicus. B. Pedetontus superior. C. Pedetontus yosemite. D. Pedetontus sii. A. and B. aer Silvestri (1911). C. and D. reproduced from Sturm (2001),
copyright Wiley-VCH Verlag GmbH & Co. KGaA. Reproduced with permission.
23. Lateral ocelli nearly touching each other (separated by 0.01-0.02 mm)
(Figure 8.D) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pedetontus sii
Lateral ocelli separated by a greater distance (Figure 8.C) . Pedetontus yosemite
24. Compound eyes with a relatively large length of contact (distinctly more than
half the length of the eyes); last segment of labial palp elongate and narrowly
subcylindrical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Compound eyes with smaller area of contact (about half the length of the eyes);
last segment of labial palp shorter and more conical . . . Pedetontus californicus
25. Ovipositor extending beyond terminal apices of spines of last abdominal styli
by about 1 mm or more . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pedetontus superior
Ovipositor just reaching or not reaching terminal apices of spines of last abdominal styli . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pedetontus saltator
Forms keying to P. superior or P. saltator are in need of revision. At the time of their
descriptions, males were unknown. Wygodzinsky and Schmidt (1980) noted that the
length of the ovipositor may change during development and so may not be a reliable
character for separation of these species.
26. No strong spines on distal segments of maxillary palps; processus triangularis
poorly developed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pedetontus gershneri
Strong spines on distal segments of maxillary palpi; processus triangularis well
developed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
27. Ovipositor with interlocking, stout, spine-like setae (Figure 9.B, C) . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pedetontus calcaratus
Ovipositor lacking stout, spine-like setae (Figure 9.A) . . . . . . . . . . . . . . . . . . . . 28
12
A
B
C
Figure 9: Ovipositors of Pedetontus (Verhoeffilis) species. A. Pedetontus submutans,
aer Silvestri (1911). B. Pedetontus calcaratus, aer Silvestri (1911). C. Pedetontus
calcaratus specimen from Penticton, British Columbia. (KNWR:Ento:8151)
28. Lateral ocelli extremely thin, weakly sole-shaped (i.e., weakly constricted in
the middle) (Figure 10.B) . . . . . . . . . . . . . . . . . . . . . . . . . . Pedetontus persquamosus
Lateral ocelli strongly sole-shaped (i.e., strongly constricted in the middle)
(Figure 10.C, D) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pedetontus submutans
A
B
C
D
Figure 10: Compound eyes and lateral ocelli of Pedetontus (Verhoeffilis) species. A.
Pedetontus calcaratus, aer Silvestri (1911). B. Pedetontus persquamosus, aer Silvestri
(1911). C. Pedetontus submutans, aer Silvestri (1911). D. Pedetontus submutans specimen from Sitka, Alaska (UAM:Ento:87248 or UAM:Ento:96672).
13
4
Gallery
A
B
Figure 11: Photographs of Petridiobius arcticus by Derek Sikes. A. Lucas Island, Skilak Lake, Kenai Peninsula, Alaska, on June 29, 2011. B. Sitka, Alaska on September
19, 2008. Some characteristics of the paern of scales appear to be at least mostly
consistent within this species: a pair of small, distinct, pale spots on the mesonotum
and an alternating paern of three black and two paler patches on the abdominal
tergites, the paler areas on the abdomen resembling an hour glass.
14
5
Anowledgments
Alan de eiroz provided comments that greatly improved this key. I thank Derek
Sikes, Joyce Gross, and Sco Justis for allowing me to use their photographs.
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