Key and checklist of the bristletails (Microcoryphia) ofAmerica north of Mexico

Mahew L. Bowser

May 9, 2012

1 Apology

Below is a dra checklist of and key to the jumping bristletails (Microcoryphia or Ar-chaeognatha) of America north ofMexico based primarily on existing keys (Wygodzin-sky and Schmidt, 1980; Sturm, 1983; Ferguson, 1990; Mendes, 1990; Sturm, 1991) anddescriptions (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 dras should be increasinglyaccessible. Please contact me at Matt_Bowser@fws.gov if you have questions or ifyou find problems with the key.

e institutions below are referred to in the text.CAS California Academy of Sciences, San Francisco, CaliforniaIEA Instituto di Entomologia Agraria, Portici/Napoli, Italy (Is this now

DEZA?)KNWR Kenai National Wildlife Refuge, Soldotna, AlaskaPAS Polish Academy of Sciences, Kracov, PolandUAM University of Alaska Museum of the North, Fairbanks, AlaskaUSNM U.S. National Museum of Natural History, Washington D.C.UWBM Burke Museum of Natural History and Culture, Seale, Washington

2 Chelist

Family Mailidae

Subfamily Mailinae

GenusMesomailis

SubgenusMesomailis

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Mesomailis leei Sturm, 1991Distribution: USA: California (Sturm, 1991).Type Material: holotype ♂, allotype ♀ and paratype ♂ and ♀ at CAS (Sturm, 1991).

Mesomailis nearctica Silvestri, 1911Mixomailis remingtoni Paclt, 1972Distribution: USA: Arizona (Mendes, 1992; Sturm, 1991), California (Silvestri, 1911;Sturm, 1991; Baldo et al., 2010), Colorado (Silvestri, 1911), Nevada (Sturm, 1991; Baldoet al., 2010), and Utah (Baldoetal2010, KNWR:Ento:8123).Type Material: Type ♀ and paratype ♂ and ♀ at IEA (Sturm, 1991).

Mesomailis cf. nearctica sensu Baldo et al. (2010)Distribution: USA: California, Nevada, and Utah (Baldo et al., 2010).

Mesomailis strenua (Silvestri, 1911)Mailis strenua Silvestri, 1911Pedetontus strenuus Smith, 1970Distribution: USA: California (Silvestri, 1911).

Subgenus Raroilis

Mesomailis californica Sturm, 1991Distribution: USA: California (Sturm, 1991).Type Material: holotype ♂, allotype ♀, and paratype ♂ and ♀ at CAS (Sturm, 1991).

Mesomailis canadensis Sturm, 1991Distribution: CANADA: British Columbia (Sturm, 1991). USA: Oregon (KNWR:Ento:8159).TypeMaterial: holotype ♂; allotype ♀; 9 ♂, 16 ♀, and 14 immature paratypes at USNM(Sturm, 1991).

Genus Trigoniophthalmus

Trigoniophthalmus alternatus (Silvestri, 1904)Mailis alternata Silvestri, 1904Distribution: USA: New York (Silvestri, 1911; Wygodzinsky and Schmidt, 1980); Con-necticut, Maryland, New Jersey, and Pennsylvania (Wygodzinsky and Schmidt, 1980).

Subfamily Petrobiinae

Genus Leptomailis

Leptomailis californica Sturm, 1991Distribution: USA: California (Sturm, 1991). Type Material: type ♂, allotype ♀, and aparatype ♂ at CAS (Sturm, 1991).

GenusMeximailis

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Meximailis cokendolpheri Kaplin, 1994Distribution: USA: New Mexico (Kaplin, 1994).

Genus Neomailis

Neomailis halophila Silvestri, 1911Neomailis halophilus Silvestri, 1911Distribution: USA: California (Silvestri, 1911; Benedei, 1973; Mendes, 1992).

Genus Pedetontoides

Pedetontoides atlanticus Mendes, 1981Distribution: USA: North Carolina (Mendes, 1981).Type Material: holotypes and paratypes at PAS except for two paratype ♀’s in thecollection of Luís Mendes (Luís Mendes, personal communication).

Pedetontoides cf. atlanticusDistribution: 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 Smidt, 1980Distribution: USA: Connecticu, Massachuses, New Jersey, New York, and Penn-sylvania (Wygodzinsky and Schmidt, 1980).

Pedetontus superior (Silvestri, 1911)Distribution: USA: Oregon (Silvestri, 1911).

Pedetontus sii Sturm, 2001Distribution: USA: California (Sturm, 2001).

Pedetontus yosemite Sturm, 2001Distribution: 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, 1995Distribution: USA: Arkansas (Allen, 1995).

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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)Mailis arctica Folsom, 1902Distribution: CANADA: British Colulmbia (KNWR:Ento:8195) USA: Alaska (Folsom,1902; Sturm and Bowser, 2004, KNWR:Ento:7292).

Subgenus Pacltiobius

Petridiobius canadensis Sturm, 2001Distribution: CANADA: British Columbia (Sturm, 2001).

Genus Petrobius

Petrobius brevistylis Carpenter, 1913Petrobius canadensis Paclt, 1969Distribution: CANADA: NewBrunswick andNova Scotia (Wygodzinsky and Schmidt,1980). USA: Maine, Massachuses, NewHampshire, and Rhode Island (Wygodzinskyand Schmidt, 1980)

Family Meinertellidae

Genus Hypomailoides

Hypomailoides forthaysi Paauskas and Shofner, 2010Distribution: Kansas (Packauskas and Shofner, 2010).

Hypomailoides texanus Silvestri, 1911Distribution: Texas (Silvestri, 1911).

GenusMailinus

Mailinus aurantiacus Sött, 1897Mailis aurantiacus Schö, 1897Mailinus nevadensis Sweetman, 1937Distribution: 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).

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GenusMailoides

Mailoides banksi Silvestri, 1911Distribution: USA: Arkansas (Allen, 1995), Maryland (Wygodzinsky and Schmidt,1980), North Carolina (Mendes, 1981), and Virginia (Silvestri, 1911; Mendes, 1992).

Mailoides petauristes Wygodzinsky and Smidt, 1980Distribution: USA: New Jersey (Wygodzinsky and Schmidt, 1980)

Genus Neomailellus

Neomailellus sp.Distribution: USA: Georgia (Sturm, 1984;Wygodzinsky, 1967) and Florida (Wygodzin-sky, 1967).

3 Key

1. All segments of antennae completely devoid of scales; median sclerites of uros-ternites reduced in size; each urosternite with not more than one pair of ev-ersible vesicles (Figure 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Meinertellidae, 2Scales present on at least basal antennal segments (Figure 2); median scleritesof urosternites well developed; urosternites II-V each with one or two pairs ofeversible vesicles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Machilidae, 7

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Figure 1: Photo of the head of a Meinertellid bristletail, probablyMailoides banksi,Norfolk, Virginia, March 7, 2009. Photo by Sco Justis.

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Figure 2: Macrophoto of the face of an unidentified bristletail (subfamily Petrobi-inae) from Chimney Flat, Smith River National Recreation Area, Del Norte County,California on June 11, 2008. Photo by Joyce Gross.

2. Coxal styli absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Coxal styli present, at least on legs III . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3. Lateral ocelli elongate, extending medially in front of the compound eyes(Figure 3.A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .NeomailellusLateral ocelli egg-shaped or elliptical, sublateral to the compound eyes(Figure 3.B) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mailinus aurantiacus

A B

Figure 3: Compound eyes and lateral ocelli of Meinertellidae, aer Silvestri (1911).A. Neomailellus mexicanus. B. Mailinus aurantiacus.

4. Coxa of legs II and III with styli . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mailoides, 6Coxa of legs III only with styli . . . . . . . . . . . . . . . . . . . . . . . . . . Hypomailodes, 5

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5. Labial palpi of males with a large capitate process, its apex covered with dis-tinct spines occurring proximally on the anterior face of the second segmentof the labial palpus, with only a few scaered, short spines near the base of thecapitate process. Females with dark pigment markings on at least the coxa oflegs I. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Hypomailodes texanusProcess of labial palpi of males much more triangular, lacking spines on itsapex, with an oval cluster of longer spines on a raised mound near the base ofthe process. Females without dark pigment markings on coxae. . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hypomailodes forthaysi

See Packauskas and Shofner (2010) for further diagnostic characters of H. forthaysi.

6. Clypeus predominantly light colored, with faint central longitudinal spot. Max-illary palp with segments III-V extensively darkened; second segment with onepigment spot; fourth segment of maxillary palp very short and stout, threetimes as long as wide. Coxa and femur of forelegs with very small pigmentspots, tarsus of third pair of legs uniformly darkened; basal tarsal segment oflegs I not darker than the others; anterior gonapophyses with approximately45 divisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mailoides petauristesClypeus light colored alongmiddle, broadly margined with dark pigment. Seg-ments III-V of maxillary palps with dark pigment forming narrow, dark rings;second segment of palp with two spots; fourth segment of maxillary palp slen-der, about six times as long as wide. Coxa and femur of forelegs with largepigment spots; third pair of legs with first tarsal segment conspicuously dark-ened. Anterior gonapophyses with approximately 55 divisions . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Mailoides banksi

7. Scales present on antennal flagellum . . . . . . . . . . . . . . . . . . . . . . . . . Machilinae, 8Antennal flagellum devoid of scales . . . . . . . . . . . . . . . . . . . . . . . . . Petrobiinae, 15

8. Lateral ocelli small, tear-dropped shaped, submedial . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Trigoniophthalmus alternatusLateral ocelli sole-shaped, extending laterally close to or beyond the lateralmargin of the compound eyes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mesomailis, 9

9. Coxal stylets on midleg present . . . . . . . . . . . . . . . . . . . . . subgenus Raroilis, 10Coxal stylets on midleg absent . . . . . . . . . . . . . . . . . . . subgenus Mesomailis, 14

Males of Mesomailis strenua, known from Shasta Springs, California, are unknown.Females should key out with Mesomailis leei, but M. strenua has longer spines onthe ovipositor. See Silvestri (1911) and Sturm (1991).

10. At least one pair of coxal stylets of males modified, paddle-shaped (Figures 4, 5). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11All coxal stylets of males normal, acute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

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Figure 4: Coxal stylet of midleg of aMesomailis ♂ specimen from Osoyoos, BritishColumbia (KNWR:Ento:8275).

11. Coxal stylet of hindleg of males normal, acute . . . . . . . . . . . Mesomailis sp. ACoxal stylet of hindleg ofmalesmodified, at least somewhat broadened apically12

I have seen specimens I am here calling Mesomailis sp. A from Osoyoos, BritishColumbia (KNWR:Ento:8275).

12. Coxal stylet of midleg of males modified, broadened with darkly pigmented,taered edges distally. (Figure 5). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Mesomailis sp. BCoxal stylet of midleg of males normal, acute . . . . . . . . . . . . Mesomailis sp. CI have seen a specimen keying here to Mesomailis sp. B from Hells Canyon NationalRecreation Area, Oregon (KNWR:Ento:8120). I have seen a specimen keying here toMesomailis 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; gonapophy-ses IX of female with very long setae on the proximal half, some of which aredistinctly longer than the width of the gonapophyses . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mesomailis canadensis

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Sensory field on femora I of male without fringed tubercles; hairs on proximalhalf of gonapophyses IX at most as long as width of the gonapophyses . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Mesomailis californica

14. Tips of coxal stylets III of male represented by a knob-like structure; parameresVIII absent; terminal spines of gonapophyses IX extremely small, not project-ing beyond the distal end of the gonapophyses . . . . . . . Mesomailis nearcticaTips of coxal stylets III of male of normal structure; parameres VIII highly re-duced with at most 3 divisions; terminal spines of gonapophyses IX very small,but projecting slightly beyond the distal end of the gonapophyses . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mesomailis leei

An additional, undescribed species similar to M. nearctica was partially described andfigured by Baldo et al. (2010).

15. 1 + 1 eversible vesicles only . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162 + 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 . . . . Neomailis halophilaLateral ocelli large, triangular to oval. Distal chains of the antennae with nomore than 8 subarticles. . . . . . . . . . . . . . . . . . . . . . . . . . . .Leptomailis californica

See Sturm (1991) for a more thorough comparison of Neomailis and Leptomailis.

Figure 6: Compound eyes and lateral ocelli of Neomailis halophila, aer Silvestri(1911).

17. Lateral ocelli transverse, subelliptical, pear-shaped, or slightly sole-shaped, at-taining only the apex of the ante-ocular sublateral area (Figure 7); paramerarestricted to the IXth segment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PetridiobiusLateral ocelli sole-shaped, aaining the frontal ante-ocular area (Figure 10);paramera variable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Petridiobius and its relationship with Pedetontus are troublesome at present. Most spec-imens will be keyed cleanly by these couplets because the lateral ocelli of Pedetontusspecies generally are longer and usually do extend into the pigmented frontal ante-ocular area while the lateral ocelli of Petridiobius are restricted to the ante-ocular sub-lateral area; however there are specimens which I think might be Pedetontus, subgenusPedetontus that could key either way.

Also, the current descriptions of Petridiobius are confusing. I am forming an opinionthat all Petridiobius from coastal Alaska and British Columbia should be called Petridio-bius 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 speci-mens of Petridiobius that I have seen from the Aleutians to southern British Columbiahave 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. Ovipositorwithout interlocking, spine-like setae, though terminal spine-like setae maybe present. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Paramera annulated or entire, restricted to the IXth segment. Ovipositor usu-ally without interlocking, spine-like setae, but such setae present in Pedetontuscalcaratus (Figure 9.B-C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

19. Abdominal sternites wide, obtuse. Apical spine of the abdominal stylets shortand stout. Foreleg of male modified. Female ovipositor apically with 2-4 stout,fossorial setae. Lateral ocelli widest laterally, without a constriction in theirmiddles (as in Figure 6). . . . . . . . . . . . . . . . . . . . . . . . . Meximailis cokendolpheriAbdominal sternites smaller, acute. Apical spine of the abdominal stylets longand stout. Foreleg of male not modified. Female ovipositor lacking stout setae.Lateral ocelli widest medially, with a pronounced constriction in their middlesmaking them sole-shaped (as in Figure 10.C). . . . . . . . . Pedetontoides atlanticus

I have seen specimens that appear to be nearly identical to Pedetontoides atlanticus fromBritish Columbia (e.g., KNWR:Ento:8191); however, the distal segments of the labialpalpi of males of the British Columbia specimens are more conical than in the corre-sponding illustration of male palpi of P. atlanticus (Fig. 6 in Mendes, 1981)

20. Molar area of mandible undentated or with 1-2 inconspicuous teeth; paramerashort and entire (unsegmented), the penis long and robust. Male genitalia par-tially exposed, not completely covered by the IXth coxitesPetrobius brevistylisMolar area of mandible with four well-developed teeth (sometimes wearingdown with age); paramera clearly pseudosegmented, the penis typical; malegenitalia completely covered by the IXth coxites . . . . . . . . . . . . . . Pedetontus, 21

21. 2 + 2 eversible vesicles on abdominal coxites II-VI . . . subgenus Pedetontus, 222 + 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 sole-shaped (i.e., with a strong constriction in the middle) (Figure 8.C,D) . . . . . . . 23Lateral ocelli separated by a greater distance; form variable (Figure 8.A,B) . 24

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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. Pedeton-tus sii. A. and B. aer 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 siiLateral ocelli separated by a greater distance (Figure 8.C) .Pedetontus yosemite

24. Compound eyes with a relatively large length of contact (distinctly more thanhalf the length of the eyes); last segment of labial palp elongate and narrowlysubcylindrical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25Compound 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 styliby about 1 mm or more . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pedetontus superiorOvipositor just reaching or not reaching terminal apices of spines of last ab-dominal styli . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pedetontus saltator

Forms keying to P. superior or P. saltator are in need of revision. At the time of theirdescriptions, males were unknown. Wygodzinsky and Schmidt (1980) noted that thelength of the ovipositor may change during development and so may not be a reliablecharacter for separation of these species.

26. No strong spines on distal segments of maxillary palps; processus triangularispoorly developed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pedetontus gershneriStrong spines on distal segments of maxillary palpi; processus triangularis welldeveloped . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

27. Ovipositor with interlocking, stout, spine-like setae (Figure 9.B, C) . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pedetontus calcaratusOvipositor lacking stout, spine-like setae (Figure 9.A) . . . . . . . . . . . . . . . . . . . . 28

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A B C

Figure 9: Ovipositors of Pedetontus (Verhoeffilis) species. A. Pedetontus submutans,aer Silvestri (1911). B. Pedetontus calcaratus, aer Silvestri (1911). C. Pedetontuscalcaratus specimen from Penticton, British Columbia. (KNWR:Ento:8151)

28. Lateral ocelli extremely thin, weakly sole-shaped (i.e., weakly constricted inthe middle) (Figure 10.B) . . . . . . . . . . . . . . . . . . . . . . . . . .Pedetontus persquamosusLateral 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, aer Silvestri (1911). B. Pedetontus persquamosus, aer Silvestri(1911). C. Pedetontus submutans, aer Silvestri (1911). D. Pedetontus submutans spec-imen from Sitka, Alaska (UAM:Ento:87248 or UAM:Ento:96672).

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4 Gallery

A B

Figure 11: Photographs of Petridiobius arcticus by Derek Sikes. A. Lucas Island, Ski-lak Lake, Kenai Peninsula, Alaska, on June 29, 2011. B. Sitka, Alaska on September19, 2008. Some characteristics of the paern of scales appear to be at least mostlyconsistent within this species: a pair of small, distinct, pale spots on the mesonotumand an alternating paern of three black and two paler patches on the abdominaltergites, the paler areas on the abdomen resembling an hour glass.

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5 Anowledgments

Alan de eiroz provided comments that greatly improved this key. I thank DerekSikes, Joyce Gross, and Sco Justis for allowing me to use their photographs.

References

Allen, R. T. 1995. Pedetontus gershneri, a new species of Machilidae from the inte-rior highlands of North America (Insecta: Microcoryphia). Entomological News106:195–198.

Baldo, L., A. de eiroz, M. Hedin, C. Y. Hayashi, and J. Gatesy. 2010. Nuclear-mitochondrial sequences as witnesses of past interbreeding and population diver-sity in the jumping bristletailMesomailis. Molecular Biology and Evolution URLhttp://mbe.oxfordjournals.org/content/28/1/195.full.

Benedei, R. 1973. Notes on the biology of Neomailis halophila on a Californiasandy beach. Pan-Pacific Entomologist 49:246–249.

Carpenter, G. H. 1913. e Irish species of Petrobius. Irish Naturalist 22:228–233.

Ferguson, L. M., 1990. Insecta: Microcoryphia and ysanura. Chapter 30, pages935–949 in D. L. Dindal, editor. Soil Biology Guide. John Wiley & Sons, New York.

Folsom, J. W. 1902. Papers from the Harriman Alaska Expedition. XVII. Apterygota.Proceedings of the Washington Academy of Sciences 4:87–116.

Kaplin, V. G. 1994. On the taxonomy of the genus Meximailis (ysanura, Machil-idae). Zoologischekii Zhurnal 73:119–123.

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