Brigham Young University Science Bulletin, Biological Series
Volume 5 Number 4 Article 1
2-1965
Identification of the adults, nymphs and larvae of ticks of the genus Dermacentor Koch (Ixodidae) in the western United States
E. P. Brinton Division of Parasitology, University of California, Berkeley
D E. Beck Department of Zoology and Entomology, Brigham Young University, Provo, Utah
D. M. Allred Department of Zoology and Entomology, Brigham Young University, Provo, Utah
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Recommended Citation Brinton, E. P.; Beck, D E.; and Allred, D. M. (1965) "Identification of the adults, nymphs and larvae of ticks of the genus Dermacentor Koch (Ixodidae) in the western United States," Brigham Young University Science Bulletin, Biological Series: Vol. 5 : No. 4 , Article 1. Available at: https://scholarsarchive.byu.edu/byuscib/vol5/iss4/1
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Brigham Young University AY 6 1965 hAKVAKD « II . Science Bulletin university
IDENTIFICATION OF THE ADULTS, NYMPHS AND LARVAE OF TICKS OF THE GENUS DERMACENTOR KOCH f/XODIDAE) IN THE WESTERN UNITED STATES
by
E. P. Brinton, D E. Beck, and D. M. Allied
Biological Series — Vol. V, No. 4
FEBRUARY, 1965
Brigham Young University
Science Bulletin
IDENTIFICATION OF THE ADULTS, NYMPHS AND LARVAE OF TICKS OF THE GENUS DERMACENTOR KOCH f/XODIDAE) IN THE WESTERN UNITED STATES
by
E. P. Brinton, D E. Beck, and D. M. Allred
Biological Series — Vol. V, No. 4
FEBRUARY, 1965 TABLE OF CONTENTS Page
INTRODUCTION 1
ACKNOWLEDGMENTS 1 REVIEW OF LITERATURE 2 METHODS AND TECHNIQUES 3 RESULTS 8 General Observations 8 Detailed Species Description 8 Dermacentor alhipictus 8 Dermacentor andcrsoni 10 Dermacentor halli 13 Dermacenior hunteri 15 Dermacentor occidentalis 17 Dermacentor parumapertus 19 Dermacentor variabilis 21 DISCUSSION 24 Adults 24 Key to Dermacentor males 25 Key to Dermacentor females 29 Nymphs „ 33 Key to Dermacentor nymphs 33 Larvae , 38 Key to Dermacentor larvae 38 CONCLUSIONS 42 REFERENCES 42
LIST OF FIGURES Figure Page
1. Dorsal and ventral views, m^de Dermacentor 4 2. Dorsal and ventral views, female Dcrnuiccntor 5 3. Dorsal and ventral views, iiymphal Dermacentor 6 4. Dorsal and ventral views, larval Dermacentor 7
5. Dorsal and ventral views, male Dermacentor alhipictus 9 6. Dorsal iuid ventral views, female Dermacentor alhipictus 9 7. Dorsal and ventral views, nymphal Dermacentor alhipictus 10 8. Dorsal and ventral views, larval Dermacentor alhipictus 10 9. Dorsal and ventral views, male Dermacentor andcrsoni 11 10. Dorsal and ventral views, female Dermacentor andcrsoni 11 11. Dorsal and ventral views, nymphal Dermacentor andcrsoni 12 12. Dorsal and ventral views, larval Dermacentor andcrsoni 12 13. Dorsal iuid ventral views, male Dermacentor halli 13 14. Dorsal and ventral views, female Dermacentor halli 13
15. Dorsal and ventral views, nymphal Dermacentor halli 14 16. Dorsal ;md ventral views, lar\al Dermacentor halli 14 17. Dorsal and ventral views, male Dermacentor hunteri 15 18. DorsiU and ventral views, female Dermacentor hunteri 16 19. Dorsal and ventral views, nymphal Dermacentor hunteri 16 20. Dorsal and ventral views, larval Dermacentor hunteri 17 21. Dorsal and ventral views, male Dermacentor occidentalis 17 22. Dorsal and ventral views, female Dermacentor occidentalis 18 23. Dorsal ;ind ventral views, nymphal Dermacentor occidentalis 18 24. Dorsal and ventral views, larval Dermacentor occidentalis 19 25. Dorsal and ventral views, male Dermacentor parumapertus 19 26. Dorsal and ventral views, female Dermacentor parumapertus 20 27. Dorsal and ventral views, nymphal Dermacentor parumapertus 20 28. Dorsal ;xnd ventral views, larval Dermacentor parumapertus 21 29. Dorsal and ventral views, male Dermacentor variabilis 22 30. Dorsal ;uid ventral views, female Dermacentor varicihilis 22 31. Dorsal and ventral views, nymph.il Dermacentor variabilis 23 32. Dorsal and ventral views, larval Dermacentor variabilis 23 IDENTIFICATION OF THE ADULTS, NYMPHS AND LAR\'AE OF TICKS OF
THE GENUS Dermacentor KOCH ( IXODIDAE ) IN THE WESTERN UNITED STATES'
by
E. P. Bbinton,-' D E. Beck and D. M. Allred^
INTRODUCTION
In 1910 C. W. Stiles made the following tick collections has been made. Yet even here comment as a part of a summary statement to we have encountered some difficulty in separ- liis extensive study of the stigmatal plates of ating such species of adult Dermacentor as Dermacentor ticks: "The specific determination amlersoni, parumaperttis, variabilis, and occi- of ticks is attended in many cases with con- dentalis. The greatest difficulty occurs, how- siderable difficult)-." ever, when nymphal and lar\'al specimens need The only difference between the time of to be accurately identified. Stiles and more than fifty years later is one of To facilitate a partial resolution of the prob- degree. Throughout the world today a great lem of identification, we have studied hundreds deal of attention is being directed to the studies of ticks from the western part of the United of ticks in the liirval, nymphal, or adult stages, States. This has included the larval, nymphal, due to their implication in disease transmission and adult stages. Most of the emphasis has and the maintenance of reservoirs of infectious been given to external anatomy and morphol- agents in nature. Since 1946 the Department ogy. Nevertheless, copious data have been ac- of Zoology and Entomology has been conduct- cumulated on geographic and ecological dis- ing ectoparasite natural history surveys in the tribution, seasonal occurrence, and host rela- Great Basin of the western United States. For tionships. As a result we have evolved illus- the last si.x years tick surveys have been ex- trated keys to assist in the specific identification tended to most of the western United States. of the several stages of de\'elopment of ticks Through our efforts and the generous cooper- belonging to the genus Dermacentor in the ation of others a very e.xtensive collection of western United States. Accompanying tlie keys ticks has been accumulated. is a descriptive analysis with illustrations for With the reliable keys composed by Cooley each of the following species: Dermacentor
' (1938), Cooley and Kohls ( 1945 ) , Gregson albipictus, D. amlersoni, D. halli. D. hunteri, D. (1956) and others, identification of the adult occidentalis, D. parumapeiius, and D. variabilis.
ACKNOWLEDGMENTS
Glen M. Kohls and Carleton M. Clifford, helpful in technical assistance in preparation of United States Public Health Service, Rocky specimens. Mountain Laboratory, Hamilton, Montana, have Others among many who have been espec- been very helpful in providing loans of speci- ially cooperative in making specimens available mens, access to data, counsel, advice, and cri- are Betty Davis, University of CalLfomia, H;is- ticism during the course of this study. Eleanor tings Natiu-al History Reservation; Elmer John- K. Jones of the same laboratory has also been son, University of Utah Ecological and Epi-
'Research supported (in part) by National Institxites of Health projects E-1273 and AI-01273-08. ^Division of Parasitology, University of California, Berkeley. 'Department of Zoology and Entomology, Brigham Young Uni\ersity, Provo, Utah. Bbicham \'ounc Univehsit*' ScuiNCE Bulletin zoological unit at Dugway Proving Ground; direction of D. M. Allrcd, a junior author of Clyde M. Scngi-r, Western W'asliington State this paper.
College, Beliingham, W'asliington; (Jliarles L. Special recognition is given the Institute of Douglas, Mesa Verde National Park. Colorado; Allergy and Infectious Diseases, National In- and Charles Hansen, Desert Ciaine Range, Las stitute's of Health, United States Public Health Vegas, Nevada. Selby Herrin. graduate student Service, whose grants in aid (Projects E-1273 at Brigliam Young University, materially as- and AI-01273-08) in part supported this study. sisted in the technical preparation of specimens. Tlie Department of Zoology and Entomolog)' at All of the tick specimens collected during the Brigham Young University extended assistance B.Y.U.-A.E.C. ecological studies at the Nevada in providing space and equipment, plus the Test Site, Mercury, Nevada, 1959-1964, were rich resource of tick collections made over many available for study. This project was under the years.
REVIEW OF LITERATURE
At the turn of the centurv' there were a made a special study of chaetota.xy for the number of workers studying ticks in the United genus Dermacenior. In an independent study States, seriously attempting to devise means of of chaetotaxy conducted by Clifford and .-Vnas- specific identification. Papers bv Salmon and tos ( 1960 ) , they chose the terminolog)' pro- Stiles (1901), Banks (1907, 19()8, 1910), and posed by Glashinskaya - Babcnko (1949), in- the publication by Stiles (1910) concerned cluding new names for those setae not hereto- with his study of the stigmatal plates of Dcnna- fore mentioned. Reznik ( 1950) presented a com- centor species are some of the more important parative morphological study of the larvae of ones which relate to the present investigation. the genus Dermacenior. Reznik (1956) also
However, Cooley ( 1938 ) was the first person completed another general moqihological study to attempt the formulation of kevs applicable of the larval stage of D. mar States is concerned. shown to be sensillae and not spiracles as pro- To find reliable anatomical and morpholo- posed by Salmon and Stiles (1902) and Delpy gical characters for the determination of species (1938), and also referred to as such bv Oude- in the immature stages, Russian and American mans (1906), Zebrowski (1926), and Cooley workers have done considerable work with (1938). Cerny (1957) utilized the presence or chaetotaxy and general moq^hologj-. Moskach- absence of a dermal .sensilla ^ sensilla haiistifor- eva (1948) worked with the larval and nymphal mia) located on the palps to separate the larval stages of Dernuucnior maigiiidtus (Sulz). L Adult specimens were removed from 70% slide-ringing compound. Very little distortion of alcohol and examined in the unmounted con- general body form resulted with tliis method. dition by the following method. Ticks were sup- Specimens which had been killed and fixed in ported on a mold of typewriter cleaner putty, the Oudeman's preservative cleared much faster permitting manipulation of the specimen to any than specimens killed otherwise and preserved desired position, with the use of fine-tipped for- in 70% ethyl alcohol. O. Universal Illum- ceps. A pair of A. Spencer Drawings of the immature stages were made inators was found adequate for good lighting from slide specimens selected from a series. The of magnification. Leitz stereo- at a wide range A shdes were examined by use of a Zeiss phase- magnifications microscope was used for from contrast microscope. Selected specimens were 10 to 216 diameters. placed on a Leitz microslide projector and pro- In making drawings of the adults an ocular jected to Quadrille paper ruled ten squares to grid was used to insure accurate location of the inch. A penciled outline was made showing anatomical parts. Illustrations were made free- general anatomical features. Anatomical and hand on Quadrille paper rule CERVICAL GROOVE. EXTERNAL SPUR JNTERNAL SPUR iSENITAL PLATE COXA II PUNCTATIONS. SCUTUM. LATERAL GROOVE PIRACULAR PLATE MACULA OBLET CELLS SENITAL GROOVE ANAL PLATE POSTANAL GROOVE fESTOONS Fig. 1. Dorsal and ventral views, male Dcnnacentor. Biological Series, Vol. 5, No. 4, February, 1965 CHELICERAL SHEATH J>ALPUS BASIS CAPITULI POROSE AREA CERVICAL GROOVE £XTERNAL SPUR PUNCTATIONS, SENITAL ORIFICE SCUTUM .INTERNAL SPUR MARGINAL GROOVE. ORSAL PROLONGATION FESTOONS. Fig. 2. Dorsal and ventral views, female Dermacentor. Bbicjiam Young University Science Buixetin CHELICERAL SHEATH JHYPOSTOME DENTICLE ARTICLE III ARTICLE II ARTICLE I LATERAL POINt SCAPULA BASAL SPUR CERVICAL GROOVE JNTERNAL SPUR EXTERNAL SPUR EXTERNAL SPUR 5PIRACULAR PLATE .GOBLET CELLS J>OSTANAL GROOVE FESTOONS, Fig. 3. Dorsal and ventral views, njmphal Dennaccntor. Biological Series, Vol. 5, No. 4, Februahy, 1965 LATERAL POINT .INTERNAL SPUR COXA II EXTERNAL SPUR EXTERNAL SPUR ANAL PLATE FESTOON Fig. 4. Dorsal and ventral view.s, larval Dermaccntor. Abbreviations of setal nomenclature: Cd, centrd dorsal; Md, marginal dorsal; Mv, marginal ventral; Pa, preanal; Ph, posthypostomal; Ptn, premarginal; Sc, scutal; Ss, scutal sensilla; Snag., sensilla sagittiformia; St, sternal. ) Bricilam Vocsc UNiNEKsrrY Science Bulletin Measurements of the length of ticks are ex- atomical and morphological features for this study is that of Cooley (1938). Setal terminol- clusive of the capitulum. i.e., from the ape.v of og)' in tlu" labelled drawing of the lar\'al stage the scapula to the median-posterior margin. is after Clifford and .\nastos (1960). The term Measurements are given in millimeters and dermal scimlUi is after Cemy (19.57). The terms were made on unengorged specimens. .Mean seiisilla porosa and scutal scnsilla are after Rob- compared against the mean scutal length was ertson (1961). Tlie terms scnsilla sagittiformia, scutal idiosomal length to get a per c-ent mean sejisilUi hatistiformia, and scnsilla auriformia are length for each species in the larval stage. those used by Dinnik and Zumpt (1949) and General terminology used to designate an- Clifford and Anastos (1960). RESULTS General Observ.\tions Dermacentor albipictus (Packard), 1869 Male (Figure 5) The general anatomical and morphological features which were emphasized as character- Body: Idiosoma variable from a typical oval istics important to this study are described be- shajx? tapered at the anterior end to elliptical low. with weakly curved sides. .\n elongate form Eyes are present in all de\el()pmental stages. was observed to be more characteristic for this Ornate scuta were observed only in the adult species than others. Length: .Ma.ximum, 6.2; stage. Coloration is variable for both se.xes with- minimum, 3.7; mean, 4.69. W'idtli: Ma-ximum, in each species. Punctations are absent in the 3.8, minimum, L7; mean, 2.8. nymphal and larval stages. Capitulum: Length greater than width. Palps having a short, broad, terminally blunt appear- Festoons are present in all stages. The adults capituli width greater than length. and nymphs ha\e eleven festoons and the larvae ance. Basis of moderate length yet prominent. nine. Cornua Scutum: Cervical grooves short, about twice Hvpostomes of all adults have dentition files as long as broad. Scutal punctations small, often of 3/3 in number. Hypostomes of the n\Tnphs indistinct but constant in size. and larvae have dentition files of 2/2 in number. The number of denticles in a given file and the Coxae: Coxa 1 with elongate internal and secondary dentition around the corona are var- external spurs, opposing margins of spurs par- iable within a given species. Hypostomal length allel. External spiu-s present on coxae II, III, varies according to the developmental stage, and I\', each being acute. Internal spurs present being longest in the adults. on coxae II and 111, but sub-acute to indistinct. Postanal grooves were observed in the adults Spiracular plate: Subcircular, with dorsal and nymphs, but not in larvae. Genital grooves prolongation present or absent, broad and blunt were observed in the males and females and a v\ hen present. Goblet cells large and constant in similar t\'pe groove was obser\ecl in the nymphs. size. 4 are labeled drawings of Figures 1, 2, 3, and Female ( Figure 6 each se.x and stage of development . Bodv: Idiosoma ovate to sub-ovate with weakly curved sides, tapering slightly toward Detailed Speciks DEsciuinio.v the anterior. Lengtii: Maximum, 5.3; mininuun, 3.2; mean, 4.45. Width: Maximum, 3.8; mini- There now follows a description, with illus- mum, 2.0; mean, 2.63. Unengorged s[x»cimens trations, of features observed in each develop- from Montana largest, those from New Mexico mental stage for each species involved in tliis smallest. studv. Onlv those characteristics are eni[)liasizcd which for the most part are considered noces- ('apituluni: Length greater tlum widtli. l'al[)s SiU^' to separate the species involved. sliort, broad, and apically blunt. Basis capituli Biological Series, Vol. 5, No. 4, Febhuahy, 1965 Fig. 5. Dorsal and ventral \ie\vs, male Dermaccntor Fig. 6. Dorsal and ventral views, female Dermacentor albipictus. albipictus. width greater than length. Cornua sub-acute der. Lateral margins weakly curved. Length: and distinct. Maximum, 2.3; minimum, 2.0; mean, 2.15. Width: Maximum, 1.1; minimum, 0.8; mean, 0.95. Scutum: Cervical grooves varying from short and rounded to moderately elongate. Puncta- Capitulum: Short with short, broad, apically tions small and not numerous. blunt palps. Basis capituli narrow having short, indistinct lateral points. Small, sub-acute cornua Coxae: Co.xa I with elongate internal and present. Basal spurs present. external spurs, opposing margins parallel. Ex- ternal spurs present on coxae II, III, and IV. Scutum: Elongate with a distinctly curved Internal spurs present on coxae II and III, small posterior margin. Cervical grooves long and but distinct. narrow. Spiracular plate: Sub-circular as in male, Coxae: Coxa I with an external spur of mod- having large goblet cells of constant size. Dor- erate size and an internal spur of small size. sal prolongation present or absent, broad and External spurs present on coxae II, III, and IV. blunt when present. Internal spurs absent on coxae II, III, and IV. Spiracular plate: Large and broadly oval. Nymph (Figure 7) Goblet cells large and distinct, from fifteen to Body: Idiosoma distinctly elongate and slen- twentv in number. 10 Bhicham Young University Scienxe Bulletin Fig. 8. Dorsal and fiitral \iews, lanal Dcrnmcentor alhipictus. Dermacentor andcrsoni Stiles, 1908 Male (Figure 9) Fig. 7. Dorsal and ventral views, nymphal Dermacen- tor aU'ipicttts. Body: Idiosoma tvpicallv oval, tajx^ring an- teriorly. Genital plate distinct. Length: Maxi- Larva (Figure 8) mum, 5.5; minimimi, 2.6; mean, 4.71. Width: Maximum, 3.7; minimum, 1.65; mean 2.57. Body: Idiosoma witli lateral margins broadlv oval. Length: iiiaximimi, 0.619; inininuiin, 0.572; Capitulum: Distinctly longer than wide, mean, 0.592. W'idtii: ma.ximiim, 0.538; minimum, generalh' rectangidar. Palps of moderate width, 0.500; mean, 0.534. apicaih' sub-acute. Basis capituli width greater than length. C'ornua of moderate length and Capitulum: Dorsal width greater than length. sub-acute. Palp.s broad and short. Basi.s c-apituii narrow. Lateral points indistinct. Sensilla porosa pres- Scutum: Extending entire length of idiosoma. ent. Punctations mcnlerate to large and distinct. Cer- Scutum: Per cent mean scutal lengtii 46.5%. vical grooves three times as long as broad. Lat- Prominentlv curved posterior margin. Cervical eral groove short or incomplete. groo\'es elongate, with sides parallel. Scutal scn- Coxae: Coxa I with opposing margins of in- sillae variable in their placement and may be ternal and external spurs parallel. External spur present or absent. slender. External spurs of coxae II, III, and I\' Coxae: Coxa I with a sub-acute internal longer than wide and acute. Internal spurs on spur. Marginal, indistinct spurs on coxae II and coxae II and III present, but \'erv reduced. III. Coxa \\ large and posteriorlv elongate, in some ) Biological Series, \'ol. 5, No. 4, Febrlahy, 1965 11 Fig. 10. Dorsal and \entral views, female Demiacentor andersoni. Fig. 9. Dorsal and ventral views male DermticetUor andersoni. Scutum: Punctations \ary from small to large, distributed beyond posterior margin of specimens extending to le\el of tlie anterior scutimi. Posterior margin of scutum irregularly margin of anal plate. cur\ed. Cer\ical grixnes elongate. Spiracular plate: Oval, with. a long, slender Coxae: Coxa I with opposing margins of ex- width. dorsal prolongation of variable Macula ternal and internal spurs parallel. External spur variable in size and shape. Goblet cells of mod- longer than the internal. External spurs pre- size macula, becoming progressi\e- erate around sent on coxae IL III, and I\', die widdi greater ly smaller toward the peripiiery of tiie plate. than length. Internal spurs present on coxae II and III, marginal and sub-acute. Female (Figure 10) Spiracular plate: 0\'al to sub-oval in out- Body: Idiosoma broad with a distinctly line, with distinct dorsal prolongation. Goblet curved lateral margin. Length: Maximum, 4.9; cells of moderate size around macula, becoming plate. Macula minimum, 3.0; mean, 3. 58. Width: Maximum, smaller toward periphery of the 2.75; minimum. 1.9; mean, 2.15. large and \ariable in shaj>e. Capitulum: Length slightlv greater than Nymph ( Figiu-e 1 1 width. Palps moderate in w idtli and extending anterior to the Inpostome, apicalK' rounded. Body: Idiosoma elongate, lateral margins Basis capitidi width greater than length. Cornua broadh' cur\ed. Length: Maximum, 1.45; mini- broad sub-apically. Porose areas large and dis- mum, 1.3; mean, 1..33. \\ idth: Maximum, 0.95; tinct. minimum, O.SO, mean, 0.90. L'nIVEBMTY SciENCE BlLLETIN 12 BlIK.HAM VOLNC Larva (Figure 12) Bodv: Idiosoma oval, tapering anteriorly. Lateral edges prominently eiir\ed. Length: Maxiimim, 0.662; minimum. 0.624; mean, 0.642. \\ idtli: Maximum, 0.543; minimum, 0.460; mean, 0.504. Capitulum: Dorsal width greater than length. Palps of moderate width and apieally sub- acute. Dermal sensilla present on article IL Lateral points distinct. .Ainterolateral edge ir- regularly curved. Posterodorsal margin of basis curved. Scutum: Per cent mean scutal length 38.7%. Cervical grooves extending posteriorly half the distance of the scutum. Four pairs of scutal sensillae. Presence or absence oi scutal sensillae variable. Coxae: Internal spur on coxa 1 semi-acute. Broad sub-acute spurs present on co.xae II and III, marginal or post-marginal. Fig. 11. Dorsal aiid ventral views, nymphal Dt'nnact-n/or audersoiii. Clapitulum: Width greater than length. Lat- eral points of basis capituli prominent, extend- ing be%'oiid apex of scapula. .Anterolateral edge of basis irregularh- curved. Palps apieally round- ed. Basal spurs proiniiu'iit. Scutum: Posterior margin prominently curved. Cervical groovf long and narrow . proxi- mal margins not parallel. Coxae: Coxa I with external spur large and internal spur moderately small and prominent. External spurs \ariable in size. External spurs present on coxae II, III, and I\', marginal and sub-acute. Internal spurs absent. Spiracular plate: Large and sub-eireular. .\ ring of mocleratcK large goblet cells around the macula, remaining goblet cells of moderate Kig. 12. Dorsal and \eiitral \ii-us, lar\al Dcmuiccntor size. iindcrioni. Biological Series, Vol. 5, No. 4, Febbu.\by, 1965 13 DermacentOT halli Mcintosh, 1931 Spiracular plate: Of medium size and oval, having small goblet cells. Dorsal prolongation Male (Figure 13) of moderate width and length. Macula small. Body: Idiosoma broadly oval. Length: Maxi- mum, 3.7; minimum, 3.4; mean, 3.56. Width: Female (Figure 14) Maximum, 2.6; minimum, 2.3; mean, 2.47. Body: Idiosoma broadly oval, lateral edges Capitulum: Dorsal length equal to width. distinctlv curved. Marginal groo\e distinct in Palps short and broad, apically rounded or unengorged specimens. Length: Maximum, 4.1; blunt. Basis capituli distinctly broader than minimum, 3.9; mean, 4.07. Width: Maximum, long, small punctations present. Comua of mod- 2.65; minimum, 2.6; mean 2.62. erate length and acute. Capitulum: Dorsal width equal to length. Scutum: With small punctations. Cer%ical Palps short and broad, apically sub-acute. Basis grooves short and rounded. Lateral groove not capituli width greater than length, lateral edges well defined. cur\ed. Comua short and sub-acute. Coxae: Coxa I with internal and external Scutum: Long and broad, extending poster- spurs present. Opposing margins of spurs diver- iorly approximately half the distance of the gent. External spurs acute on co.Kae II, III, and idiosoma. Punctations small, sparse and located IV. Internal spurs present on coxae II and III, anteriorh- on the scutum. Cervical grooves marginal and rounded. Coxa I\' moderately tvvice as long as broad. small. Fig. 13. Dorsal iind ventral views, male Dermacentor Fig. 14. Dorsal and \entral views, femiUe Dermacentor 7ia//i. halli. 14 Bhiciia.m Young University Science Bulletin (^oxae: Coxa I witli internal and external Ciapitulum: Dorsal width greater than lengdi. spurs, opposini; margins of spurs cli\ergent. Ex- n\j>ost(>iiie slender. Palps long and slender. ternal spur (lisfinttly longer than internal spur. Basis capituli with distinctly elongate, acute External spurs present on coxae 11, III, and 1\', lateral points. Comua absent. Anterolateral mar- acute. Internal spurs sub-acute, present on coxae gin of basis broadly convex. Basal spurs mar- II and 111, absent on I\'. ginal and sub-acute. Spiracular plate: 0\al and somewhat flat- Scutum: Distinctly elongate, extending pos- tened. Macula moderately large and variable in teriorly over half the distance of the idiosoma. form. Goblet cells imiformlv small o\er entire Cervical gr(K)ves long, proximal margins not plate. Dorsal prolongation of moderate width parallel. and length. Coxae: Coxa I with external spur broad at base and apically acute. Internal spur indistinct. Nymph (Figure 15) Small external spurs present on coxae II and III. External spur on coxa I\' reduced to a relatively Body: Idiosoma long and slender, lateral indistinct marginal rounded elevation. margins weakly curved, tapering anteriorlv. Length: .Maximum, 1.3; minimum, 1.3; mean, Spiracular plate: Small and sub-circular, with 1.3. Width: Maximum, 0.75; minunum, 0.70; a small, blunt dorsal prolongation. Several me- mean, 0.725. dium-sized goblet cells adjacent to the small round macula, f^emaining goblet cells small. Lar\a (Figure 16) Body: Idiosoma oval in shape, tapering an- teriorlv. Length; Maximum, 0.705; minimum, 0.581; mean, 0.642. Width: Maximum, 0.654; minimum, 0.480; mean, 0.563. Fig. 1.5. Dors.il .111(1 .fiitra! vii-xvs. iivmphal Dcrmacen- Fig. 16. Dorsiij and ventral views, larval DcrmacciUor lor Iwlli. hatli. Biological Series, Vol. 5, No. 4, Februahy, 1965 15 Capitulum: Dorsal width greater than length. Capitulum: Dorsal length greater than Palpal ape.K sub-acute. Dermal sensilla present. width. Palps of moderate width and apically Basis capituli with lateral points moderately blunt. Basis capituli width greater than length. slender yet distinctly acute, extending beyond Comua of moderate length, semi-acute. ape.x of scapulae. Sensilla porosa present. Scutum: Punctations small and constant in Scutum: Broadly curved pKJSterior margin. size. Cervical groove short, twice as long as Per cent mean scutal length 47.7%. Cerv^ical \\ide. Lateral groove indistinct. grooves long and narrow. Scutal sensillae vari- Coxae: Coxa I with opposing margins of able in number. internal and external spurs parallel. Co.xae II, Coxae: Coxa I with a broad, sub-acute spur. III, and I\' with external spurs semi-acute. In- Coxae II and III with sub-marginal spurs. ternal spurs on co.xae II and III very much reduced. Coxa I\' moderatelv large. Dermacentar hiinteri Bishop, 1912 Spiracular plate: Oval, with a slender dor- Male (Figure 17) sal prolongation. Goblet cells around macula moderately large, medium-sized in the dorsal Body: Idiosoma distinctly broad posteriorly prolongation. Macula large and variable in and laterally, tapering anteriorly. Festoons shape. large. Length: Maximum, 4,3; minimum, 3.85; mean, 4.09. \\'idth: Maximum, 2.8; minimum, Female (Figure 18) 2.5; mean, 2.66. Body: Idiosoma oval with tapering antero- lateral margin. Marginal groove distinct in un- engorged specimens. Length: Maximum, 4.0; minimum, 3.6; mean, 3.7. Width: Maximum, 2.8; minimum, 2.1; mean, 2.4. Capitulum: Width greater than length. Palps extending beyond hypostome and rounded api- cally. Basis capituli with lateral edges curved, width greater than length. Comua broad and sub-acute. Scutum: Distinctly tajjered posteriorly, e.x- tending half the length of the idiosoma. Puncta- tions variable in size. Cervical grooves short, twice as long as broad. Coxae: Coxa I with opposing margins of in- ternal and external spurs parallel. Internal spur longer than the external. External spurs on coxae II, III, and I\' as wide at base as long. Internal spurs present on co.xae II and III, wider than long. Spiracular plate: Oval in shape with a mod- eratelv broadened dorsal prolongation. Goblet cells moderatelv large, smaller in the dorsal prolongation. Macula \ariable in size and shape. Nymph (Figure 19) Body: Posterolateral margin of idiosoma broadh' curved. Anterolateral margin slightly curved and tapering. Length: Maximum, 1.55; minimum, 1.45; mean, 1.47. Width: Maximum, 1.2; minimum, 1.0; mean, 1.09. Capitulum: \\ idtli at widest point equal to Fig. 17. Dorsal and ventral views, male Dermacentor liuntcri. length. Anterolateral margin of basis capituli 16 Briciiam Younc Un'ivehsity Science Bulletin Fig. 18. Dorsal and ventral views, female Dermacentor huntcri. Fig. 19. Dorsal and ventral views, nymphal Dermacen- irregularly curved. Basis with lateral projection tor hunteri. extending beyond ape.\ of scapula. gin tapered. Idiosoma sub-circular. Length: Scutum: Short, e.xtending posteriorly one- Maximum, 0.638; minimum, 0.516; mean, 0.595. third the idiosomal length. Length of cers'ical Width: Maximum, 0.540; minimum, 0.475; mean, grooves approxiinatel)- six times greater than width. 0.501. Coxae: Coxa I with external spur as broad Capitulum: Width at lateral points greater at base as long. Internal spur on coxa I small, than it'ugth. Palps broad and apicallv rounded. indistinct; marginal when present. External Dermal sensilla and sensilla porosa absent. Lat- spurs on coxae II, III, and I\', marginal, rounded eral point of basis capituli extending bevond and small. apex of scapulae. Anterolateral margin of basis inegidarh' curxed. Spiracular plate: Oval, sub-aeuteK' taperi'd dorsallv. Coblet cells small compared to those Scutum: Per cent mean scutal length 35.3%. of the adult. .A ring of slightly larger goblet Length about one-third that of idiosoma. Pos- cells siirroimd the macula. terior margin onl\- slighth curved. Cervical grooves with margins divergent. Lana (Figure 20) C'oxae: Coxa 1 with a brt)ad sub-acute in- Body: [diosoma with posterior and mid-lat- ternal spur. Coxae II and III with broad jxist- eral margins broadl\- cur\eil, antcroiatciai mar- inarginal external spurs. ) Biological Series, Vol. 5, \o. 4, February, 1965 17 Fig. 20. Dorsal and ventral views, larval DermaceiUor hunteri. Dcnnuccntor occidciitalis Marx, 1892 Fig. 21. Dorsal and ventral male Dermacentor occidentalis. Male ( Figure 21 Body: kliosoma elongate and oval. Lateral Spiracular plate: Large and oval with dorsal margins prominenth' cur\ed, tapering antero- prolongation moderately broad and blunt. Gob- laterally. Length: Maximum, 3.8; minimum. 2.7; let cells distinct, not extending to apex of dorsal mean, 3.3. Widtli: Maximum, 2.5; minimum, prolongation. Macula large, variable in shape. 1.85; mean, 2.25. Capitulum: Dorsal width as great as lengtii. Female (Figure 22) Palps short and broad and apically blunt. Basis oval and tapering at the capituli width greater than length. Cornua elon- Body: Idiosoma anterolateral margin. Marginal groove distinct gate, apicallv \arving from blunt to pointed. in imengorged specimens. Length: Maximum, Scutum: Punctations unifonn in size, tend- 3.6; minimum, 2.6; mean, 3.2. Width: Maximum, ing to be small. Cervical grooves short, rounded 2.3; minimum, 1.7; mean, 2.06. and pit-like. Lateral groo\e indistinct. Capitulum: Dorsal width equal to length. Coxae; Coxa I with opposing margins of in- Palps short, apically blunt. Basis capituli dis- ternal and external spurs parallel. Spurs large tinctly broader than long. Cornua large but not and prominent. External spurs present on coxae as elongate as in the male. Porose areas broadly II, III, and l\'. acute. Internal spurs present on oval. coxae II and III, broadly curved. Coxa IX var- iable in size, in some cases extending posteriorly Scutum: Extending posteriorly approximat- to level of anal plate. ely half the length of the idiosoma. Punctations BlIIGIIAM VolNG I'siVERSI'n SCIENCE BULLETIN Fig. 22. Dorsul and ventral views, female Dermacentor Fig. 23. Dorsal and ventral views, nymplial Dermacen- occidentalis. tor occidentalis. few yet distinct and constant in size. Cervical Capitulum: Dorsal width slightly greater grooves short, broad and siiallow, extending than length. Palps long and slender. Basis cap- fan-like posteriorlw ituli \\ith lateral points extending bevond apex of scapulae. .\nteroIateral margin of basis ir- Coxae: Coxa I witli opposing margins of in- regidarly cursed. Basal spurs postmarginal. ternal and external spurs parallel. Kxferiial spurs on coxae II, III, and \\. In- acute to suh-acute. Scutum: Kxtends posteriorly one-third to ternal spurs present on coxae II III. mar- and oni'-halt the length of the idiosoma. Cer\'ical ginal and broadly rounded. grooves long, deepened anteriorly. Posterior Spiracular plate: Inner and posterior mar- margin cur\ed. Punctations absent. gins straight. .Short dorsal prolongation present. Coxae: C^oxa I with a medium-sized exter- Cohlet cells of moderate si/e. siiglitK snuiiicr nal spur and a marginal inti'rnal s\t\\T, External than in the male. Macula large. spurs present on coxae II ;ukI III. .\ slight mar- ginal projecting external spur may be present Nymph ( Figiue 2-3) or absent on coxa I\'. Body: Idiosoma oval, anterolateral margins Spiracular plate: Essentially oval, broadly eveiilv tapering. Latiral gr Ma.ximiim, 2.9; minimum 2.6; mean, 2.72. Width: Ma.ximum, 1.9; minimum, 1.6; mean, 1.71. Capituluni: Length greater than width, and rectangular. Palps of moderate length and api- cally rounded. Basis capituli width greater than length. Comua short, wider than long and api- cally rounded. Scutum: May or may not extend entire length and width of idiosoma. Some puncta- tions large, interspersed among slightly smaller punctations which predominate. Cervical grooves of moderate length, deepened anter- iorly. Pro.ximal margins of grooves parallel. Short lateral grooves present at posterior half of body. Coxae: Coxa I with opposing margins of internal and external spurs divergent. External spurs present on coxae II, III, and IV. Internal spurs absent on coxae II, III, and IV; however, indistinct marginal elevations may be present on coxae II and III in some specimens. Fig. 24. Dorsal and ventral views, lar\'al DermacentOT occidentalis. Larva (Figure 24) Body: Idiosoma oval. Lateral margins dis- tinctlv curved. Length: Maximum, 0.634; mini- mum, 0.529; mean, 0.582. Width: Maximum, 0.582; minimum, 0.437; mean, 0.466. Capitulum: Width slightly greater than length. Palps of moderate width and length, apicallv rounded and equal to length of hypo- stome. Basis capituli with lateral points extend- ing beyond apex of scapulae. Posterodorsal margin of basis straight to slightly concave. Scutum: Per cent mean acutal length 41.3%. Extends posteriorly over one-third the length of the idiosoma. Cervical grooxes extend half the length of the scutum. Scutal sensilla present. Coxae: Coxa I with internal spur semi-acute. External spurs compressed and broadened on coxae II and III. Dermacentar pariimapertiis Neumann, 1901 Male (Figiu-e 25) Body: Idiosoma elongate, oval and lateral Fig. 25. Dorsal and ventral views, male DermacentOT margins may be irregularly curved. Length: parumapcrtus. ) 20 BniciiAM VoL'Nc University Scien'ce Blxletin Spiracular plate: Moderately small, oval, gin distinctly curved. Cervical grooves elongate, witli a liroad clorsal prolongation. Size of gob- divergent, widening very much posteriorly. let cells variable with those adjacent to the Large punctations predominate in numbers over macula slightlv larger. .Macula large, variable smaller, more moderately sized punctations. in size and shape. Punctations confluent in the area of the cervical grooves. Female ( Figure 26 Coxae: Coxa I with opposing margins of internal and external spurs divergent. External Body: Idiosoma broadly o\'al with the lateral spurs present on coxae H, III, and I\'. Internal margins cur\ed. Length; Maximum, 3.15; min- spurs present only on coxae II and III. imum, 3.1; mean, 3.13. Width: Ma.ximum, 2.15; minimum, 2.0; mean, 2.08. Spiracular plate: Broadly oval, with a dis- Capitulum: Length slightly greater than tinct dorsal prolongation. Goblet cells relatively width. Palps moderately long and etjual to constant in size. length of hyjXJStome. Basis capituli broad and short. Lateral margins distinctly curved. Comua Nymph (Figure 27) width greater than length, short and blunt. Por- Body: Idiosoma elongate, oval, with lateral ose areas prominent and sub-circular. margins irregularly curved. Length: Maximum, Scutum: Extends half the length of the idi- osoma in imengorged specimens. Posterior mar- Fig. 26. Dorsal and ventral sicws, fomiJe Dcrmarcntor Fig. 27. Dors.il :iik1 \fiitral \icws, nymphal Dcmta- panimapcrliis. ccnior parumupcrtus. Biological Series, Vol. 5, No. 4, February, 1965 21 1.45; minimum, 1.14; mean 1.3. Width: Max- imum, 1.0; minimum, 0.75; mean, 0.86. Capitulum: \\'idth slightly greater than length. Palps moderately long, e.xtending slight- ly bevond ape.x of hypostome. Anterolateral margin of capitulum irregularly curved. Basis capituli with lateral points extending beyond apex of scapulae. Posterodorsal margin of basis straight. Scutum: With posterior margin distinctly ar- cuate. Cervical grooves long, posteriorly shal- low, anteriorly deepened, with opposing mar- gins parallel. Scutum extends over one-third the length of the idiosoma. Coxae: Coxa I with external spur moderately small; internal spur indistinct in some speci- mens. External spurs present on coxae II, III, and IV, rounded, marginal and small. Internal spur on coxa IV difficult to discern in some specimens. Spiracular plate: Sub-circular with dorsal prolongation very short to none at all. Goblet cells uniformly small, except for a ring of slightly larger cells surrounding the macula. Larva (Figure 28) Body: Idiosoma broadly oval. Length: Max- imum, 0.754; minimum, 0.662; mean, 0.707. Fig. 28. Dorsal and ventral views, larval Dermacentor panimapertus. Width: Maximum, 0.605; minimum, 0.509; mean, 0.571. Capitulum: Length greater than width. Palps Capitulum: Width greater than length. Palps short, broad, and apically rounded. Comua of moderately broad and apically rounded. Der- moderate length and blunt. Basis capituli width mal sensilla present. Basis capituli with moder- exceeding length. ately short lateral points. Anterolateral margin Scutum: Widely scattered large and small irregularly curved. punctations. Due to size the larger punctations Scutum: Per cent mean scutal to idiosomal indicate dominance in numbers but the smaller length 36.3%. Posterior margin broadly arcu- punctations actually are greater in numbers. ate. Scutum extends posteriorly one-third the Cervical grooves moderately deep, short, with idiosoma length. Cervical grooves of moderate pit-like posterior depressions. length, opposing margins parallel. Coxae: Coxa I with opposing margins of Coxae: Coxa I with internal spur broad and internal and external spurs parallel. Coxae II, sub-acute. Broad, slightly elevated external III, and I\' with acute external spurs. Internal spurs on coxae II and III. Internal spurs absent. spurs broadly curved on coxae II and III. Spiracular plate: Large and broadly curved Dermacejitor variabilis (Say), 1821 inwardly, straight outwardly. Dorsal prolonga- tion variable in length and widUi. Goblet cells Male (Figure 29) minute and constant in size. Macula variable in Body: Idiosoma elongate and oval. Lateral shape. margins irregularly curved anteriorly, posterior Female (Figure 30) margin rounded. Length: Maximum: 4.4; mini- mum, 3.5; mean, 3.9. Width: Maximum, 2.85; Body: Idiosoma elongate and oval. Lateral minimum, 2.3; mean, 2.42. margins irregularly curved anteriorly with pos- 22 Bhigiiam Young University Science Buij.£tin Fig. 29. Dorsal and ventral views, male Dernutcentor Fig. 30. Dorsal and ventral views, female Dcrmacentor variabilis. variabilis. terior margin evenly rounded. Marginal grcxjve equal to length. Internal spurs present, margin- distinct in iinengorged specimens. Length: Ma.\- al, blunt, and apically rounded on coxae II and imiim, 4.3; minimum, 3.65; mean, 3.96. Width: III, absent on coxa I\'. Maximum, 2.95; minimum, 2.3; mean, 2.57. Spiracular plate: Large and sub-circular. Capitulum: Length greater than width. Palps Coblet cells numerous, minute and uniform apicall)- blunt. Basis capituii width greater than size. Macula oval and large. Dorsal prolonga- length. Cornua short and apically rounded. Por- tion distinct and elongate. ose areas bean-shaped. Scutum: Large punctatioiis predominate in Nymph (Figure 31) numbers over small punctations. Punctations extend beyond the posterior margin of the scu- Body: Idiosoma ovulate posterior, anteriorlv tum. Scutum extends half the distance of the elongate and tapering. Length: Maximum, 1.5; idiosoma. Cervical gr(M)ves narrow and pit-like minimum, 1.4; mean, 1.44. Width: Ma.ximimi, anteriorly. Posterior margin of scutum sharply 1.0; minimum, 0.9; mean 0,94. arcuate. Capitulum: Width equal to length. Palps Coxae: Coxa I witii opposing margins of in- Icmg and slender. Anterolateral margin of basis ternal and external s|>urs parallel. External spurs capituii straight to weakly concave. Lateral present on c-oxae II, III, and 1\\ with b.usal width points of basis long and slender, extending well Biological Series, Vol. 5, N'o. 4, Februarv, 1965 23 0\ Fig. 32. Dorsal and ventral views, larval Dermacentor variabilis. Larva (Figure 32) Fig. 31. Dorsal and ventral views, nymphal Derma- Body: Idiosoma elongate with lateral mar- centor variabilis. gins distinctly cur\ed. Length: Maximum, 0.656; minimum, 0.5S2; mean, 0.628. Widdi: Maximum, beyond apex of scapulae. Posterodorsal margin 0.518; minimum, 0.504; mean, 0.509. of basis essentially straight. Basal spurs sub- acute and distinct. Capitulum: Dorsal length greater than width. Palps somewhat slender. Dermal sen- Scutum: Posterior margin distinctly arcuate, silla absent. Anterolateral margin of basis cap- extending from one-third to one-half the length ituli irregularly curved. Lateral points of basis of the idiosoma. Cervical grooves elongate and prominent. Posterodorsal margin of basis slender. straight. Coxae: External spur on coxa I semi-acute, Scutum: Per cent mean scutal length 38.9%. large. Internal spur small and relatively indis- Posterior margin slightlv irregular. Cervical tinct. External spurs present on coxae II, III, and grooves shallow, with margins parallel. Scutum IV, but somewhat indistinct especiallv on coxa extends posteriorlv one-third to one-half the IV. length of the idiosoma. Spiracular plate: Sub-circular, with inner margin straight. Goblet cells minute, numerous, Coxae: Coxa I with a broadly based, dis- and uniform in size. There may be a ring of tantK- acute internal spur. Sub-marginal, broad slightly larger goblet cells surrounding the mac- external spurs present on coxae II and III may ula. appear as slight elevations or wrinkles. 24 Bhioiiam Young University Science BummN DISCUSSION The following discussion is presented in three and nvmphs are essentially those applied by units referrable to the adults, nymphs, and lar- Cooley (19.38) and Arthur' (1960) with some vae. In e<»ch instance there is a general discus- minor modifications. In the larvae a number of sion of anatomical and morphological features features were selec-ted by the writers and others as observed in this study for all the species in from a number of sources. It h;is been neces- each stage of development. Concluding each Siuy in some instances in all stages of develop- dis- separate discussion is an illustrated key for the ment to resort to the use of geographic-al identification of the species. tribution, altitudinal differences, host-parasite The anatomicid and morphological charac- relationships, and other features as a means of teristics used in the illustrated keys for the adults ta.\onomic separation. Adults Body: Idiosomal lengths and widths in gen- in D. albipictus, D. halli, and D. occidentalis, eral are in agreement with those of Cooley and rec-tangular (wider from side to side than (1938). All species conform to a general oval anterior-posieriorly ) in D. aiulersoni, D. panim- shape posteriorly with tapered anterolateral apertus, D. hunteri, and D. variabilis. Some ex- margins. Some variation in body outline was ceptions between the sexes were noted. For in- observed in females, which may be due per- stance the D. variabilis male has a somewhat haps to the lack of the scutiim not covering the square capitulum, while the female is rectan- dorsum as in the male. Nevertheless body size gular. was variable both within sjx'cies and between Scutum: Coloration observed in the adults species. Male specimens of D. albipictiis from is variable in both sexes and within each species, Montana are the largest ticks observed. Some so it is not useful for our purposes. For descrip- are over 6.0 mm in length. Specimens of D. tion of coloration in Dcrmaccntor ticks see Coo- albipictiis from Utah averaged 4.5 mm in length. ley (1938). Those from New Mexic-o averaged 3.7 mm in While shallow and deep grooves on the length. Similar variation in length was found idiosoma could generally be distinguished, suf- in unengorged females of this species from the ficient variation exists to prohibit their use as same localities. Variation in size was also noted key characteristics. General size and shape of the in other species, but there was nothing so con- cerviciil grooves, however, were found to be sistent and dramatically different as observed constant. Punctations in both sexes ;u-e always in D. albipictus. separate and distinct, except for the female of The most variable body features observed D. parumapertus where some of the large punc- between the species are palpal length and width, tations are confluent. length of comua and shape, spiracular plate Length of the scutum in the females is more shape and size, number and size of goblet cells or less constant in relation to the overall length wliich are described as being large, small, and of the idiosoma. In general, the posterior margin minute. There are variations also in size, distri- extends posteriorlv from one-third to one-half bution, and number of dorsal punctations. This the idiosomal length in unengorged specimens. is also tnie of the size and shape of the cervical Coxae: In general the greatest variation in grooves. All of these features, however, are rel- the coxal size was found in co.xa IV of the atively constant within aiiv given spec-ies and males. D. albipictus from Montana has a dis- to be reliable features which may be used seem tinctly larger coxa IV than specimens of the taxonomically. same species from New Mexico. Tliis was read- The distribution, numbers, and size of setae ilv measured bv noting the distance from the were found to be most \'ariable in the adult anal plate to the posterior apex of cx)xa I\'. Co.va stage. For these reasons it was decidtxl that I\' on D. aiulcrxoni from western Colorado is chaetotaxy is too unreliable to use in separating tlie largest observed for all species. It extends the species, at least for Dcrmaccntor in the [XJSteriorly to the level of the anterior margin western United States. of the anal plate, .\ similar situation was found Capitulum: Two general forms were ob- with D. occitlciitali.s: Coxa I\' in D. variabilis served in the capitula of the adults. It is sijuare and D. halli is the smallest observed in males. Biological Series, Vol. 5, No. 4, Februahv, 1965 25 Co.xa IV in the females is constant for any given Utah, and northern Nevada being narrowly di- species. Co.xae I, II, and III also are generally vergent, and specimens from the southern part c-onstant for any given species. There is a good of Utah and Nevada being broadly divergent. deal of variation in position, number, shape and External spurs are consistently present on size of co.xal spurs between species, but relatively all four coxae. Internal spurs are present on constant for each species. coxae I, II, and III and absent on coxa IV. The D. parumapertus and D. halU have the prox- length and width of the internal spurs vary imal margins of the spurs on coxa I divergent. markedly, from marginal rounded elevations to In D. halli this divergence is apparently con- acute spurs. On the other hand, external spurs stant. In D. parumapertus the divergence varies, are more constant in form. Variation in length with specimens from Idaho, Wyoming, northern and width does exist, however. Key for the Identification of Species of Denmiccntor Males 1. Opposing margins of spurs on coxa I parallel 2 Opposing margins of spurs on co.xa I not parallel 6 Cornua about twice as long as broad. Scutal punctations noticeably small. Cer- vical grooves short, terminally rounded and pit-like D. occidentalis (See figure 21) Distribution along tlie Pacific coastal plain, mainly in central and northern California, western Oregon, and in southwestern Wash- ington. 26 Bhicflam Vounc University Science Bulletin Corniiu li'ss than twice as long as broad. Mixture of large and small pimctations on seiitiiin. C^oniparatixe size of punefa- tions shown in couplet illustration. Cer- vical grooN'es usually elongate and pit- like. Lateral grooves deep and elongate when present 3 Co.xa IV large, posterior margin almost at the level of the anterior margin of the anal plate. External spur on coxa IV longer than wide. Coblct cells of med- ium size, pore visible and distinct, cells becoming smaller toward periphery' of spiracuiar plate and especially' the dorsal prolongation .. D. aiulcrsoni (See figure 9) Most common [Dcrmacentor) tick of larger vertebrates in the region ot its distribution which is ill the liigliir elev'ations of the (jreat Basin states; northern Arizona, northern New Mexico, western Colorado, all of Utah, Nevada, northeastern California; and from the raoimtain and lowland areas of eastern Oregon, eastern Washington, Idaho, Wyoming, Montana and western Canada. In higher elevations of Creat Bxsin states it is the most common tick para- site of the porcupine. This is the common "Wood Tick" which as an adult attacks m;ui, many of his domestic animals, and larger native vertebrates. The next most abundant tick in the s;iine regions of distribution is Dcrmacentor alhipictus. Biological Series, Vol. 5, No. 4, February, 1965 27 Goblet cells of uniform size in the cen- tral area of the spiracular plate. They are either ver\' small, giving a granular tex- ture to the plate, or xery large, with goblet pore distinct. Posterior margin of coxa IV does not extend to anterior level of anal plate. Basal vvidtli of external spur on coxa IV as broad as long 4 Goblet cells very small and granular-like. General shape of coxa IV square. Exter- nal spur on coxa IV stout and blunt .... D. variabilis (See figure 29) In the western U. S., distribution is limited to the north and central coastal plains region of California and extreme southwestern Oregon. Occasional collections may be made in other parts of western U. S., but these will most likely be taken from dogs in transit from the eiistcm U. S. where this species is most com- mon and widely distributed. Goblet cells very large, pores very dis- tinct. Spiracular plate variable in shape. Coxa IV longer than broad S Vounc UNivEHsm' Science Bulletin 28 Bricham 5. Dorsal prolongation of spiracular plate narrow. Goblet cells in the neck of the prolongation smaller than tliose around the macula D. htuUeri (See figure 17) The principal host is the Desert Bighorn sheep. Mule deer in the range of the Desert Bighorn sheep also host this tiek. Two collee- tions have been taken from higomorph.s and several from mim. Distribution at present re- strieted to higher elevations. Desert Bighorn sheep range in mountain areas of New Mexico, Arizona, and southern Nevada. They may be found at lower elevations (2500-3500 feet above sea level) in migrating from one range to another. Specimens found on man and lago- morphs in southwestern Utah and southeastern Nevada were atx)ut 3000 feet above sea level. Dorsal prolongation of spiracular plate broad and short to absent. Goblet cells very large and constant in size with pores distinct. Goblet cells the largest of any species of Dcrmacentor in western U. S D. albipwliis (See figure 5) So far the only known single-liost Dcrmacentor tick in the western U. S. It is a common par- asite of deer and elk at higher elevations in the Great Basin states, and of larger vertebrates such as moose, horse, elk, antelope, Hocky Mountain sheep and deer in the northern tier of states in the western U. S. and in Canada. Scutal punctations a mi.xture of large and small with the smaller predominating in number. Cervical grooves three to four times longer than broad, deepened an- teriorlv and open posteriorly. Lateral grooves distinct at posterior half of b(Kly D. parumapcrtus (See figure 25) Known from lowlands of southern Idaho, south- eastern Oregon, east of the coastal ranges in California, lowlands of Nevada, Utah, Colo- rado, Arizona, New Mexico, western Tcxa.s, western Oklahoma, and northern Mexico. The California Black-tailed jackrabbit is the most common host and it is very unusual to collect adult ticks of this species on other hosts. 29 Biological Sehies, Vol. 5, No. 4, February, 1965 Scutal punctations small and uniform in size. Cervical grooves short, deep and pit-like. Lateral grooves relativelv indis- tinct. Goblet cells small, similar to D. variabilis D. halli (See figure 13) At present known only from south-central Texas and Central America. Apparenlty the peccary is the principal host. Key for tiiic Identification of Species of Deniuiccntor Femalf.s In each couplet where the species is listed, refer to geographic distribution information and host parasite relationships described in the key of identification for the males of Dcruuiccntor. 1. Opposing margins of spurs on co.xa I parallel 2 Opposing margins of spurs on coxa I divergent 6 30 BniciiAM YouNC University Science Bitli-etin Coriuia as long as broad. Stutal pimcla- tioiis s|)arsi'ly scaffcrcd, shallosv but ot till- same size. Cervical groovt-s siiort, shallow and cxpaiiding faii-iikf p)Stcr- iorlv I) ocridnildlis (Sec figure 22) Cornua broader than long. Seutal piinc- tations mixed in size, large to minute. (.See eooplet illustration for comparative .sizes.) (xMAieal groo\cs elongate but distally closed. Porose areas large and ovulate 3 AJ .Spiracular plate vvith u;(iblet cells so min- ute as to display a grannlai tixture, most densely concentrated around the macula. Porose areas usually bean-shaped D. vaiiahilis (See figure 30) Biological Series, Vol. 5, No. 4, February, 1965 31 Spiracular plate witli medium to very liU'ge goblet cell.s 4 Goblet eells of medium size, usually smaller in tlie dorsal prolongation, which is long and nanow D. atulerxoni (See figure 10) Spiracular plate with large, evenly dis- tributed goblet cells. Tlie pores of the goblet eells veiy distinct 5 Spiracular plate with very large goblet cells, constant in size. Dorsal prolonga- tion of spiracular plate broad truncate, or lacking. Palps with article III twice as wide as long D. (ilhipichis (See figiu^e 6) Spiracular plate with large goblet cells but not constant in size, those in the dorsal prolongation slightly smaller. Dor- sal prolongation elongate and always present. Palps usually elongate, article ill as long as broad D. htnitcri (See figure 18) 32 Brigham Younc University Science Bui.letin Spiraciiliir plati' with goblet ct-Hs med- ium and constant in size. Punctations on seiitmn laii;f. (A-nical gr()o\e long, deep and expanding [posteriorly D. jxirtiwapertus (See figure 26) Spiracular plate with goblet cells minute in size. Scutum with small punctations except at [KMipherv, where they are shglith- larger. Cer\ical groove short and sluiUow D. luilli (See figure 14; Biological Series, Vol. 5, No. 4, February, 1965 33 Nymphs The number and placement of setae in the curved. No particular form of cervical groove nymphs are too variable to be of use in separ- can be described as typical. ating the species considered in this study. Coxae: The external spur on coxa I is dis- lateral points of the b;isis capituli in The tinct in each species. D. andersoni has the larg- D. alhipictus are the shortest observed in all est with D. variabilis possessing the next largest. species. lateral points on the basis capituli The D. parumapertus has the smallest spur for coxa of D. halli are the longest of all species exam- I. The external spur on coxa IV of D. occiden- ined. The lateral points of D. halli and D. vari- talis and D. parumapertus is indistinct to absent. (ihilis extend well beyond the apex of the scap- The internal spur on coxa I is somewhat uni- ulae. formly distinctive although it is essentially small Palpal length and width are variable between in all the species. species. Short, broad palps were observed in Spiracular plate: distinct variation was D. alhipictus while long, slender palps were A observed both in the size of plates and goblet found in D. occidentahs and D. variabilis. cells. D. albipictus has the largest spiracular Basal spurs ;u-e present on all species with plate and goblet cells. D. variabilis has a rela- the exception of D. huntcri. They are most dis- tivelv large plate, but the goblet cells are com- tinct on D. occidentahs. paratively minute. D. huntcri has the smallest Scutum: Punctations and ornamentation are spiracular plate. In e\ery species, with the ex- absent in the nymphal stage. Size of scutum is ception of D. albipictus. a ring of larger goblet distinctly variable. D. halli has the largest and cells surrounds the spiracular opening. Variation D. huntcri the smallest. The curvature of the in the number and placement of the ring of posterior margin is also variable among the goblet cells is the rule. They are the largest in species with D. halli having a broadly curved, D. andersani and next largest in D. paruma- almost truncate margin. D. huntcri is weakly pertus. Key for the Identification of Species of Dermacentor Nymphs Refer to geographic distribution and host parasite information as given for males for each species listed below. Idiosoma elongate and slender. Lateral margins weakly curved. Scutum variable in posterior miuginal conformation, ex- tending more than half the length of the idiosoma 34 Briciiam Vounc UNrvEiisiTY Science Bulletin Idiosoina moderately broad. Lateral mar- gins distinctly curved. Scutum extends less tlian onc-Iialf tlie length of the idiosoma 3 Basis capituli narrow, with lateral points small and p Basis capituli broad with lateral points distinct and shaq>. I\d[)s long and slen- der. Spiraeular plate oval, goblet cells minute with a circle of slightly larger goblet cells centrally locatetl D. lioUi (See figure 15) Little i.s known of tile I'cology )f th pecifs in niitiirc. Life e)'cle data ar( known only from laboratory observations. Biological Series, Vol. 5, No. 4, Februaby, 1965 35 Coxa I with internal spur indistinct. Basis capituli with basal spurs indistinct or absent 4 Coxa I with internal spur small but well defined. Basis capituli with basal spurs distinct 5 Basis capituli with lateral points moder- ately long, posterior border irregular. Anterolateral border slightly convex in outline. Coxa I witli external spur ;is broad as long. Spiracular plate flatiron- like, with broad base inward. Goblet cells minute except for a ring of slightly larger goblet cells located around the macula D. hunteri (See figure 19) Life cycle data have been obtained from lab- oratory observations. Little is known of host parasite relationships of tliis species in nature. 36 Bricham Vounc University Science Bulletin Basis capituli with lateral points of med- ium lengtl), the anterolateral edge straight. Posterior border uniformly even. Co.xa I with e.xternal spur moderately small and as broad as long. Spiracular plates rounded, with a ring of relatively large goblet cells clustered around the macida D. parumapterus (See figure 27) The nymphs of this species arc found on small rodents such as kangaroo rats, several species of pocket mice, deer mice ami ground s(iuir- rels located in the geographic areas where the adults are found. In general the largest host on which nymphs of this .species are found is the Black-tiiiled jack rabbit. Spiracular plate small, ovoid, yet some- what flattened inwardly. Co.xa I with well-defined internal spur imd an exter- nal spur which is located almost mar- ginally. External spur about as broad as long D. occidentalis (See figure 23) Found on a number of species of smaller \er- tebrates. Spiracular plate large, ovoid, not depress- ed on inward surface. Goblet cells vary in size from minute to medium. (See couplet illustration.) Very distinct larger goblet cells situated ring-like around the macula. Coxa I with distinct internal and external spurs. The internal spur on coxa I is deflected outvvard 6 Biological Series, Vol. 5, No. 4, February, 1965 37 Basis capituli with anterolateral margin slightly elevated. Palps not slender. Gob- let cells of moderate size. Large goblet cells closely associated with macula D. andersoni (See figure 11) Nymphal stage found on smaller vertebrate species, mainly rodents t)pical of higher eleva- tions. Such animals as tree squirrels, voles, deer mice, chipmunks, jumping mice, wood- rats, prairie dogs and the marmot are com- mon hosts. As one progresses toward more northern latitudinal geographic areas, the hosts for the nymphal stages vary. Nevertheless, there is a tendency for this species as nymphs to have a wide range in size of host selection, from marmots to deer mice. Basis capituli with anterolateral margin slightly depressed. Palps slender (com- pared to D. andersoni). Goblet cells minute except for a ring of slightly larger goblet cells around tlie eccentrically lo- cated macula D. variabilis (See figure 31) Although there are an abundimce of data con- cerning the hosts of this species in the eastern and midwestcm United States, the data are hmited with reference to the western United States. 38 Bricham Young Univeksit^- Science Bulletin Larvae Body: C.oneral idiosomal form essentiallv points, extending beyond the scapular apex. oval for all species. Both length and width The lateral points of D. halli are more tapered variable. D. iilbipictus is the most broad (sub- than in other species. The posterodorsal margin circular). D. jHiruiiuipertus has the greatest of the basis capituli and the lateral points are mean width and D. occiileulalis has the nar- best obsersetl on unmounted specimens. Tlie rowest. The posterolateral margins are distinctly capitulum naturally projects shghtly downward rounded in all species. and thus makes it difficult to observe these Four pairs of sensilla sagittiformia are pres- structures accurately on mounted specimens. ent, one pair jX)sterior to each coxal plate (Ssag Palpal length and width are variable be- not shown on fig. 4 [X)Stcrior to 1st co.xal plate), tween species. D. alhipictus has the shortest and and one dorsolateral pair on the opisthosoma. widest palps, and D. variabilis has the longest Due to their constant position they are of taxo- and narrowest. The apices of the palps vary level. nomic value at least at the generic Various from rounded, as in D. htiiUeri, to sub-acute in other sensillae were seen and studied. For exam- D. alhipictus. Dermal sensillae occur on all the sensilla haustiformia ple, were observed on the species except D. albijyictus, D. hutiteri, and D. scutum, postscutum, basis capituli, palps, and variiihilis. leg segments. Dermal sensilla, sensilla porosa, and the scutal sensillae are sensilla haustiformia Scutum: In comparative per cent mean ac- according to Dinnink and Zumpt (1949). Nev- tual length D. hunteri has the shortest scutum, ertheless, onlv those sensillae observed on the being 35.3% that of the idiosoma. palps, basis capituli and scutum are included Commonly four pairs of scutal sensillae are in the drawings in this study. Further study on present. Five pairs were infretjuently seen and the comparative position of the sensilla hausti- in some specimens only two or three were formia is needed to more fully determine tlieir observed. Cervical grooves were observed on taxonomic utility at the species level. unmounted specimens at a magnification of 216 The general arrangement of setae is rela- diameters, but were variable in shape. tively constant in all species studied. Tliis is in Coxae: A single spur is present on each coxa agreement with Clifford and Anastos (1960). in all species. Coxa I has an internal spiu" and Because enough other characteristics are pre- coxae II and III external spurs. The spurs are sent to use for identification pur|X)ses, chae- generally constant in position, size, and shape totaxy was not emphasized. for each species. The width or acuteness of the Capitulum: D. alhipictus has the niyrowest spur on coxa I is utilized as a taxonomic char- basis capituli. Its lateral projections do not acter in the kev. Coxa I on D. alhipictus is at- extend beyond the apex of the scapula. All tached more anteriorly on the idiosoma than in other species in this study have distinct lateral the other species. Key ion tiik Idkntification of Species of Dcrtnaccittor Lahvae For use with mounted specimens, except where noted in the key. 1. Dermal sensilla present 2 Dermal sensilla absent 5 Biological Series, Vol. 5, No. 4, February, 1965 39 Lateral projections of basis capituli ta- pering narrowly, ending in acute lateral points (best observed on unmounted specimens). Spurs on coxae II and III submarginal D. halli (See figure 16) Known only from south-cential Texas and Mexico. Very little is known of natural ecology. Lateral projections of basis capituli not narrowly tapering but ending sub- acutely. Spurs on co.xae II and III mar- ginal. (Couplet illustration shows dorsal and ventral views of basis capituli and lateral points.) Best observed in un- mounted specimens 3 3. Spur on coxa I broadly tapered and sub- acute D. parumapertus (See figure 28) Known from lowlands of southern Idaho, southeastern Oregon, east of the Sierra Nevada mountains in California, all of the lowlands of Nevada, Utah, western Colorado, Arizona, New Mexico, western Texas, western Okla- homa, and nordiem Mexico. The larval stage is found on practically all the smaller verte- brates distributed in the areas above. The adults are almost invariably found on the Black- tailed jack rabbit, Lepus calijornicus, but at certain seasons adults, nymphs, and larvae may be taken from this host. This is without doubt the most abundant Dcrmacentor tick distributed in the lowland regions of the Great Basin states. Spur on coxa 1 moderately tapered 4 40 BnicHAM VouNc Univer>.ity Science Bulletin Posterior margin of basis capitiili straight to slightly t-oncave. Sensilhi porosa pres- ent. Sides of cervical grooves not parallel D. occidentalis (See figure 24) Distribution limited more or less to plains region of northern California and southwestern Oregon. Knowledge of host-parasite associa- tion for immature ticks of this species shows a wide variety of smaller vertebrates. Posterior margin of basis capituli weakly curved. Best observed on unmounted specimens D. aiulersuni (See figure 12) Known from mountainous areas in northern Utah, Nevada, and eastern slopes of the coa.st- al range in iiortliem CaUfornia. Mountain areas are generally interpreted as above 5,000-foot elevations above sea level. Ticks are also in both mountain and lowland areas of eastern Oregon, ciistem Washington, most of Idaho, Wyoming, Montana, and western Canada. Hosts for the lar\'ac constitute a great number of species of smaller mammalian vertebrates distinctive for the gcograpiiic area where the tick species is distributed. Basis capituli with lateral points much reduced, not extending beyond the sca- pulae. Spurs on co.\ae II and III very indistinct D. albipiclus (See figure 8) ^ n " Single host tick. If immature ticks are col- lected during winter months from large verte- brate hosts, they most likely will be this species. Basis Ciipituli with lateral points extend- ing beyond scapulae. Spurs on c-o.xae II and III distinct 6 Biological Series, Vol. 5, No. 4, Febru.\ry, 1965 Spur on coxa I acute. Spurs on co.xae II and III not extending beyond posterior margin of plate. Margins of cervical grooves parallel. Best observed on un- mounted specimens. Posterior margin of scutum prominently curved D. variabilis (See figure 32) Very little known about the host-parasite rela- tionships in the larval stage for this species in the western United States. Spur on coxal plate I sub-acute. Spurs on coxae II and III postmarginal. Mar- gins of cervical grooves divergent. Best observed on unmounted specimens. Pos- terior margin of scutum slightly curved D. hunted (See figure 20) Little known about the host-parasite relation- ships in the larval stage for this species of tick. 42 Uhicmam Voi'Nc University Science Bulletin CONCLUSIONS Several thousand specimens of larval, by other characteristics: Dermal sensilla, nymphal and adult ticks of the genus Derrna- shape, position and size of lateral points, capituli, general morphol- cenlor distributed in tlii' western United States form of the basis have been examined. Tlie main emphaiis was ogy of the cervical grooves, shape of the centered on selec-ted anatomical and morpho- posterior scutal margin, and the size, form logical features. N'e\erthelcss such factors as and position of the coxal spurs. liost parasite relation- geographic distribution, 4. Reliance on geographic distribution and host con- ships and aititudinal distribution have been parasite relationships is still needed in mak- sidered. Tliis has all been done in order to con- ing specific identification of all stages. This tribute to information which will facilitate spe- requires c-oncentrated life history studies of their cific identification of Dennacctitor ticks in all of the known species examined on a various developmental stages of growth. More basis of ecologically similar geographic reg- obvious conclusions which may be drawn from ions. This is true with some of our better- this study are as follows: known species such as D. andersoni, D. par- unuipertus and D. occidentalis. For such features used by previous workers for 1. Those species as D. halli and D. Iiunteri little is separation of adults and nymphs specific known about their life cycles under natural part reliable. There is still are for the most c-onditions. enough variation within species and between 5. The illustrated keys and descriptions in this some species to create problems. Therefore, study should help provide a better under- it will still be necessarv' to adjust identifi- standing of die species of Dermacentor ticks cation descriptions by the inclusion of local- in the western U.S. It is our plan for sub- ized features to fit the needs when a specific sequent studies to examine each spec-ies in identification is made. For example, the de- each developmental stage in our collections, gree of coxal spur divergence is somewhat using the present stiid)' as the principal ve- \ariable. Yet this feature plus aititudinal dis- hicle of analvsis. Each species will be stud- tribution and host parasite relationship for ied separately, and the information will be a given locality will provide a more accur- published as individual separate papers, in- ate identification. cluding all data we have accumlated plus nymphs such 2. For specific identification of that made available to us, as well as from the shape of the anterolateral features as the literature. It is hoped that other workers margin of the basis capituli and the position may find the present paper useful for pur- length and form of the lateral points, and poses of identification of Dermacentor ticks spiracular plate, width of palpi, shape of the in the western U.S. In due proc-ess of time position size of goblet cells, size, shape and certainlv the combined efforts of several of internal and external spurs on coxa I, workers will materi;Uly unra\el and re\eal a size and form of the cervical groove are re- more accurate imderstanding of the biolog\' used. liable characteristics which may be of the stages of development for ticks in the 3. For the specific identification of liu-vae the western U.S., not only for Dermacentor. but following may be reliably used, accompanied for all species of ticks as well. REFERENCES Allred, D. M., D E. Beck and L. D. White. — . 1908. A revision of the Ixodoidea, or 1960. Ticks of the Genus Ixodes in Utah. ticks, of the United States. Tech. Ser. No. Brigham Young Univ. Sci. Bull., Biological 15, Bur. Entom., U.S. Dept. Agric. Series, l(4):l-42. the — . 1910. The scientific name of Monograph of Arthur. Don R. 1960. Ticks, a spotted fever tick. Jour. Am. Med. Assoc, Part V. Cambridge Uni\'. the I.xodoidea, 55:1574. Press. Becjuaert, C. 1946. The ticks, or I.xodoidea, Banks, Nathan. 1907. Note on a new classi- J. States East- fication of ticks (summary of paper). Proc. of the Northeastern United and Entom. Soc. of Washington, 8:62. ern Canada. Ent. Americana, 25:73-120. : Biological Series, Vol. 5, No. 4, February, 1965 43 Bishopp, F. C. 1911. Some new North Amer- — . 1955. Studies in morphology and ican I.xodidae with notes on other species. systematic-s of i.xodids. (In Russian.) Avto- Proc. Biol. Soc. Washington, 24:197-208. reg. Dissert, M:3-12. . 1912. A new species of Dermacentor -. 1958. Materials concerning the larvae and notes on other North American Ixo- and nymphs of the Subfamily Ixodinae didae. Proc. Biol. Soc., Washington, 25:29- Banks, 1907. Parazitol. Shorn., Zool. Inst. 37. Akad. Nauk SSSR, 18:10-77. Bishopp, F. C. and H. P. Wood. 1913. The Glashinskaya-Babenko, L. V. 1949. Chaeto- biolog)' of some North American ticks of the taxy of the body of tick larvae of the family genus Dermacentor. Parasitology, 6:153- I.xodidae and its taxonomic significance. 187. ( In Russian. ) Dokl. Akad. Nauk SSSR, nov. Bishopp, F. C. and C. N. Smith. 1936. Amer- ser., 62(2):245-248. ican Tick (Dermacentor variabilis Dog Gregson, J. D. 1956. The Ixodoidea of Can- Say). Insect Pest Survey Bull., U. S. Dept. ada. Canada Dept. of Agric, Ottawa, Can- Agric, 16(5) :210. ada, Publ. 930. Bishopp, F. C. and H. L. Trembley. 1945. . 1960. Morphology and functioning of Distribution and hosts of certain North the mouth parts of Dermacentor andersoni American ticks. Jour. Parasitol., 31(l):l-54. Stiles. Acta Tropica, 17(l):3-79. Brinton, E. P. and D E. Beck. 1963. Hard- Hearle, E. 1938. The ticks of British Colum- bodied ticks of the Western United States. bia. Sci. Agr., 18:341-354. Brigham Young Univ. Sci. Bull., Biological Hoffman, A. 1962. Monografia de los Ixo- Series, 2(3) part 1:1-28. doidea de Mexico. I Parte. Revista de la Cerny, V. 1957. Morphological differences in Sociedad Mexicana de Historia Natural, larvae and nymphs of the Central European 23:191-307. members of the genus Dermacentor Koch. Hooker, W. A., F. C. Bishopp, and H. P. Wood. (In Czech.) Folia Zoologica, 6(l):23-28. 1912. The life history and bionomics of Clifford, C. M., G. Anastos and A. Elbl. 1961. sonre North American ticks. Bur. Entomol- The larval i.xodid ticks of the Eastern Un- ogy, U. S. Dept. Agri. Bull. 106. ited States (Acarina-Ixodidae). Misc. Publ. Lototsky, B. V. 1948. To the problems of Entom. Soc. of America, 2(3):215-237. study of chaetotaxy in ixodid ticks .(In Rus- Clifford, C. M., and G. Anastos. 1960. The sian.) Soobshch. Tadsh. fil. Akad. Nauk. use of chaetotaxy for identification of larval SSSR, 7:24-27. ticks. Jour. Parasitol., 46(5):567-578. . 1949. E.xperimental study of chaeto- Cooley, R. A. 1938. The genera Dermacentor taxy of ticks of genus Dermacentor. (In and Otocentor (Ixodidae) in the United Russian.) Ent. Oboz., 30(3-4): 276-286. States, with studies in variation. Nat'l. Inst. Moskacheva, E. A. 1948. To the question of Health Bull. 171, U. S. Public Health Serv. morphology of the larvae and nymphs of Cooley, R. A. and Glen M. Kohls. 1945. The the tick Dermacentor marginatus (Sulz). genus Ixodes in North America. Natl. Inst. (In Russian.) Trudy Belorussek Cel'khoz. Health Bull. 184, U. S. Public Health Serv. Inst., 13(2): 162-168. Cooley, R. A. 1946. The genera Boophilits, Nutall, G. H. F., C. Warburton, W. F. Cooper, Rhipicephahis, and Haemaphijsalis (Ixodi- and L. E. Robinson. 1908-1926. Ticks, a dae of the New World). Nat'l. Inst. Health Monograph of the Ixodoidea, Parts 1-3. Bull. 187, U. S. Public Health Service. Cambridge, England. Delpy, L. 1938. Morphologic et disposition Oudemans, A. C. 1906. As cited by H. Vitz- des stigmata respiratories chez les larves thum (1943). hexapodes des Ixodidae. Bull. Soc. Path. Reznik, P. A. 1950. On a comparative mor- E.xot, 31:298-300. phological study of the larvae of the ticks of genus Rus- F. the Dermacentor Koch. (In Dinnik, J. and Zumpt. 1949. The integ- sian.) Dokl. Akad. Nauk. SSSR, nov. ser., umentary sense organs of the laivae of Rhi- 75(2):327-328. picephalinae ( Acarina ) . Psyche, 56 ( 1 1 ) 1-11. . 1956. Morphology to the tick larvae Filippova, N. A. 19.54. To the diagnosis of sev- of the genus Dermacentor Koch. Zool. Zhur., eral species of ixodid ticks of genus Ixodes 35:1152-1162. Latr. (subgenus Ixodes s. str. ) from larvae Robertson, Richard G. 1961. A morpholog- nymphs. ( In Russian. ) Zool. Zhur., 33 ( 1 ) ical study of some larval ticks of the genus 69-76. Dermacentor with emphasis on structures ) 44 BiuciiAM YouNc University Science Bulletin of possible taxonomic importance. Thesis Zhur., .34(5): 10.37-1051. submitted for tlie degree of Master of Sci- Stiles, C. W. 1908. Tlie common tick (Dcr- ence, Brigliam Young Univ., Provo, Utah. macentor andersoni ) of the Bitter Root Val- Sahnon, A. C. and C. W. Stiles. 1902. Tlie ley. U.S. Pub. Health Rep., 2.3(27):949. cattle ticks ( Ixodoidea ) of the United Assoc, .55(22): 1909. States. 17th Ann. Rept. Bur. Anim. Ind., . 1910. The taxonomic value of the U. S. Dept. Agric, for the year 1900. pp. microscopic structure of the stigmal plates 380-491. in the tick genus Deimaccntor. Hygienic Samson, K. 1908. Die Eiablage und die larve Laboratory Bull. 62, Public Health and der Zecke Rliipiccplidlus SY/dgu/iici/s (Latr. Marine Hospital Servic-e of the United Sitzunksber. Ges. Naturf. Freunde, Berlin, States. pp. 46-.5(). . 1910. The correct name for the Rocky Schulze, P. 1942. Ueber die Hautsinnesorgane Mountain spotted fever tick. Jour. Am. Med. de Zecken, besonders uber cine bisher un- Assoc, ,55(22): 1909. bekannte Art von Arthropoden-Sinnesorg- Vitzthum, II. 1943. Acarina. In Bronn's Klas- ane, die Krob\'lophoren. Zeitschr. Morph. sen un Ordnungen dcs Tierreiches, 5(3): Oekol. Tiere, .38:379-419. 3a3. Serdyukova, G. V. 1955. On the differential Zebrowski, G. 1926. A preliminary report on characteristics of lar\'ae and nymphs of ix- the morphology of the .\mcriciin dog tick. odid ticks (I.xodoidea). (In Russian.) Zool. Trans. Amer. Ent. Soc, 51:331-369. o*'