rhe Host-asociatioii\ of the lice of mainiiials . I35 (i. I! . J<'. HOPKLYS. MA.,O.K.E., F.R.E.S.. late. Senior 13 ntoniologist (Xedic al), Cgaiida Protectors te . [Keceived .liiiic. 7. I04h 1 (With 1 figlire 111 the. tcst.) Cumi*;sw. 1 . IXTIWDGI;T~OS............................................ (I) (4 oneral .......................................... (2) The classificat.ion of the lice of triammals ....... (3) What is a species .................... ....... (4j Thc extent. of our kiiowledye ....................... (3) AMetlliodsof' collecting lice frorn inammills .............. (ti) ,Methods of I)reservut.iw and vsarniria.tiori of liri: ...... (7) Aeknowledgnients ......................... 11. U1OLoc:Y OF L1O.E ......................................... (1) General ......................................... (2) Food ............................................ (:3 j Keaet.ions t.o trmperd lire ......................... (4)Ecologicel niches ................................. ( .7 ) Loiise-pop.ilat. ions of host-individuals ................ (ti) (:omposition of loiist?-~~op~~l~tio~i~..... (7) Effect on the host ................................ (8) Natural enemies ................................ (9) Symbiotic organisms ........................... I 10) Transfer from host to host. .......................... (1 I) Host-specificity ............. (1 2) Straggling and runt.amination ...................... ( 13) Primary and secondary infestittioris ................. (14) Secondary ahwncc .... ( 15) Geographical factors .............................. ILL A HOST-LISTOF THE LICE OF MAMMALS ...................... Procedure followed iri rompilirig t.ho iist ... ( I ) ihlonotremata .................................... (2) Marsupialia ...................................... (3) I&ectivora (4) Dermoptera ...................................... (3) Chiroptera .................. (11) Cetacea ... .................. (12) Carnivora ........................................ (13) Tubulidentata ................................. (14) Proboscidea ..... ............................. (18) Artiodactyla ...................................... IV . LICE AND THE PHYLOGENY OF THEIX HOK~S .................. V . DrscussioN ow THE HOST-LIST . (I) General ......................................... (2) Monotremata . (3) Marsupialia ... (4) hectivora ... (5) Dermoptera ... (6)Chiroptera .... (7) Primates ..... (8) Edentata ..... (9) Pholidota ........................................ 388 G. 11. E. HOPKINS (10) Lagomorpha ............. (1 1) Hodeiitia ................................ (12) C‘etaccs ................................ ( 13) Carnirorti ................................ (11) Ti<)Jllli&ntatii .................................... ( 16) l’roboscidea .......... ......................... (16) Hyracoidea, ....................................... (I i) Sirenia ........................................... (1s) PcrissodactyliL ............... (19) ArtiodactyL$ ...................................... \’I. THE .\P\’TIQUITY OF LICE AS PAlL4Y1TEY OD’ VER (1) IF-ious iittempts to iitilixe the evidence. ............. (2) bvidence from ~n~tmnmals.......................... (3) Evidence from hi& .............................. (4) Evidence from fossils ..... (5) The evidence as a whole .......................... ViI. SLJXMARY....................... ViIL LIYW~ATUREUONSGLTEU ................................... Ix. INDEX TO NAMES USED IN THE HOST-LIST ............. (I) GEL-1 IXESAL. oci;itioiis of licc with tdicir hosts iire of’cxtri~ordiii;~~.?.iiitcrest, hiit OIIC howletlgc oftlicm is rather. mvapc, 7‘hc l~reseiit~1)al~cr origiiiatccl i~s;iii attempt to tlecliice thc ;Lntiquity of t.lic licc 11s 1)arasiites of mammals, but so maiiy iiiterestiiig and coiit,roversial points cropped up that it seemed to me that’ it would be dishonest to give mere1.y extracts from the evidence (which might be sut)coiisciously selected to suit my beliefs) and that 1 must give the evidence in full. Hence the host list, for no sut,hor since 1880 appears to have attempted the task of compiling a complete host-list of the lice of mammals, though scvcral regional or 1)i~rtiallists haw been pi blished. These two sections makc up t,lie most im1)ortant part of the paper, hut 1have :dded sufficieiit 011 otlicr itspccts of the subject to make the whole com])rohcrisil)le,so 1 hc~pe,to those readers who have 1106 mactc a special stiicly of liw, ;~ndt,o indioibttesome ciircctioiis in which it seciiis to mc that furt)hcr ~~~eii~~.liwoiiltl bo I)artiurilarly fri~it~fiil. I have iiot hesitated to use cvitlencc tlrawii from bird-lice to cxcmplify poiiits in t’he biology or distribution of the lire of niitmriii~ls. It was riot until 1 had hgun the writing of this ~qert,liiLt 1 re;rlizecl how iiirmcrous tire the permissihk rneitiiiiigs of the word I‘ relatioiisliil) ”. In this pqm the word is consistently irscd in tlic soiisc of liiiisliip ; ot,her possibblc meaiiiiigs are expressed by tho word .‘ associatioils ”. (2) THE CLASYl~i~ATlONOF THE ],ICE OY MAMMALS. It, is germally a,ccept.ctL that lice are descended from Psoeitl-like aiicestors, and they have recently been placed as an order iii the superorder Ysoc:oidea, :L posit)ion which appears to express their relationships with tjhe other irisects rat,her better than ally other wliich has been suggested. They belong to t,he niorc primitive hemimetaboloiis group of iriseds, in which the iiewly-hatched insect resembles the adult in most reslieck They were formerly divided into two orders, Mallophaga or chewing lice * niitl Anopliira or sucking lice, but it h;ts ]low been recognized that the resemblances, between these tjwo groups arc of sucli importance that all the lice may be referred to one order (fig. 1). The liarno to be applied to taliisorder is in dispute. Leach (181-5) gave tl~ Iianic Rnoplura to t,liewhole groiq) tirid Nitzscli (1818,1). 280) named the ohewiiig licc Mallophagn ; the latter name, together with Rhyncophthirina (Ferris, 1931) * Neither of the usual English names for this group is appropriate : “ bird lice ” because many species occur on mammals, and “ biting lice ” because the sucking lice must also bite before they can suick. For this reason I have substituted the less familiar but more accurate term used here. HOST-ASSOUIATIOPr'S OF THN IJCN OW MAMMALS 3X!1 for the elephant-louse, has never been seriouslj- disputed, but tlic discov that tlic chewing and sucking groups of lice are closely related and shodd be reg:ardetl as suborders has created chaos as to the use of the iitmlc Xnoplrira, i\ few ntitliors using this name for tlie whole groiip (applying the name Sipliuli- ciilata to the sucking lice), while the great majority continue to use it for thc sucking lice alone, ab wa~universal until it few j+e;trs ago. Weber (193!j) included all the lice in the order Phthiraptera. of the superortlcr Psocoidea." Since ordinal iianics are apprently not governed by tlic lhiles of Sonicriclut,iire. we are free to adopt such names as will be most widely understood and ca~c tlie rnininnini of confusion and rnisL~il~~erstalldi1~~; I have tlicreforc continiicd the iisc of Arioplura for the sucking lice uiid liavc adopted Wctxr's iiarrie Phthiraptera for the whole order Figure 121. WBLYCERA ISCHNOCERA Rtii/NCOPtiTIiiRlPJT\ ANOPLURA PSOCOPTEROID STOCK M A tentative family-tree of the l'ht,hirapterii or lice. fl'/~,t;.Ilnllopltayu arc characterized by the possession of chewing or riiiiiicii- bnli~terriouth-~)arts, more or less similar to those of the Orthoptera. They are undoubtedly the more primitive of the two suborders of the Phthiraptera, adarc theniselves divided into three very distinct superfamilies-the Bmblycem, lschnocera and Rhyncophthirina. The two former groups differ in a number of respects, but principally in the fact that maxillary palpi are present in the Amblycera but absent in the Ischnocera. For this and other reasons it is generally accepted that the Amblycera are more primitive than the Ischnocera, and the resemblances of the former to the Psocoptera are such as to leave little room for doubt that the original Mallophaga were amblycerous.? The * The suggestion that lice are related to the Psocidae seems to have been first put, forward by Packard (1887, pp. 267, 271). Kellogg (1896, pp. 468-471 ; 1902) came to the same conclusion. t Bedford (1932cc, p. 309) differs from t,he majority of authors in considering the Ischnocera to be the more primitive group, citing as evidence the presence in the Amblyceru of a special groove to protect the antenna, and the possession by certain genera of patches of setae or combs of spines on the venter of the legs and abdomen. While agreeing tbat these are specialized characters, I do not think Bedford right in his main contention, because I consider that the primitive characters of the Amblycera (particularly the presence of maxillary palpi) are more important than their specializations. But this example illustrates well the combination of primitive and specialized characters in the same group (and often in the same insect) which is so common among the Phthiraptera and which constitutes one of the greatest stumblingblocks in the way of attempts to devise a natural classification of the lice. 3 FK) (:. H. ..E. HOf'Kl xs 1.ihyi~col)ht'hirinaare a very curious groiip with on1~-oiie known rctpresentati\,t., flaeinutot/c!jzr/se1~phat~ti.s Piitget. which seems to form 1-0 sonie extent a link I)etween tlie Jlallophaga and the Aiioplura : it has clwritig mouth-parts, I)iit they are reduced iii size, iiiucli specialized,