Entomology 3rd edition - C.Gillott - Chapter 5 ppsx

5 A pter yg ote Hexapod s 1 . Intr oduc t ion Traditionally, the groups included in the term “apterygote hexapods,” namely, the Collem - b ola, Protura, Di p lura, and Th y sanura (includin g Microcor yp hia and Z yg entoma), wer e cons id ere d or d ers o fp r i m i t i ve ly w i n gl ess i nsects an dpl ace di nt h esu b c l ass A p ter yg ota ( Ameta b o l a). T h e y s h ow t h e f o ll ow i n g common f eatures: l ac k o f w i n g s, l ac k o f a pl eura l su l cus on t h et h orac i c segments, presence o f pregen i ta l a bd om i na l appen d ages, s li g h tor absent metamorphosis, and indirect sperm transfer. As more information on their structure and habits has become available, it has become a pp arent that (1) their status as insect s ( exce p t f or T hy sanura) i s d ou b t f u l an d (2) t h ere l at i ons hip o f t h e g rou p sw i t h eac h ot h er is m ore di stant t h an or igi na lly b e li eve d . Severa l aut h ors h ave t h ere f ore recommen d e d t h at t he i nsectan su b c l ass Apterygota b e reserve d so l e l y f or t h eT h ysanura an d t h at t h eCo ll em b o l a , Protura, and Diplura each be given the rank of class, with the Collembola and Protur a considered as sister g rou p s within the Elli p ura (see Fi g ure 1.11). These three g rou p s differ f un d amenta lly f rom i nsects i n severa lf eatures; f or exam pl e, t h e y are ento g nat h ous, h ave i ntr i ns i c muscu l ature i nt h e antennae, an dl ac k com p oun d e y es w hi c h are c h aracter i st ic o f most i nsects, at l east i nt h ea d u l t stage. T h us, t h eE lli pura an d D i p l ura are somet i mes considered sister groups within the Entognatha. However, other analyses indicate that the E ntognatha is a paraphyletic assemblage (see Chapter 1, Section 3.3.1) . T h eCo ll em b o l a are p ro b a bly f urt h est remove df rom t h ew i n g e di nsects. T h e yp os- sess on ly s i xa bd om i na l se g ments, a p ostantenna l sensor y or g an s i m il ar to t h eor g an o f T om¨osvary found in myriapods, gonads with lateral (rather than apical) germaria, and eggs ¨ i n which there is total cleavage. Non-insectan features of the Protura are the absence of antennae (perhaps a secondary condition associated with their soil-dwelling habit), the occurrence o f anamor ph os i s, an d a g en i ta l a p erture t h at o p ens b e hi n d t h e 11t h se g ment . D ipl ura are su p erfic i a lly s i m il ar to T hy sanura, w i t h w hi c h some aut h ors g rou p t h em. How - ev e r, i na ddi t i on to t h e f eatures ment i one d a b ove, t h ey diff er f rom typ i ca li nsects i n h av i ng u nusual respiratory and reproductive systems. Even though all Thysanura are considered in - sectan, it is now apparent that the group contains two distinct subgroups, the Microcoryphi a and the Z yg entoma ( = Th y sanur a s ensu str i ct o ) , to which some authors accord ordina l status. T h e p r i mar yb as i s f or t hi s di st i nct i on concerns t h e mout hp arts. In t h eM i crocor yphi a ( suc h as Mac h i l i s a n di ts a lli es, t h e b r i st l eta il s) t h e man dibl es h aveas i ng l e art i cu l at i on w i t h 11 3 114 C H A PTER 5 the head and bite with a rolling motion. In the Zygentoma (which includes silverfish an d fi rebrats), on the other hand, there is a dicond y lic articulation of the mandible, which thu s bi tes transverse ly as i n p ter yg ote i nsects. As note di nC h a p ter 1, diff erences i nt h e structur e an d operat i on o f t h e mout h parts are o ff un d amenta l p h y l ogenet i c i mportance . 2 . C ollembola S ynonyms : Oli gentoma, O li goentomat a C ommon name: s pr i ngta ils Sma ll to m i nute w i ng l ess h exapo d s; h ea d pro- or h ypognat h ous, antennae segmente d , compoun d e y es absent, mouth p arts ento g nathous; abdomen 6-se g mented, t yp icall y with three mediall y situated pregenital appendages (collophore on segment 1, retinaculum on segment 2, furcula on se g ment 4), g ono p ore on 5th se g ment. Collembola are abundant on ever y continent, includin g Antarctica. About 6 5 00 s p ecies h ave b een d escr ib e d , i nc l u di ng more t h an 1 6 00 f rom Austra li a, 300 f rom t h eUn i te d K i ng- dom, and about 840 from North America. Individual species may be quite cosmopolitan, sometimes as a result of human activit y when the y ma y become p ests. Structur e Collembola vary in length from about 0.2 to 10 mm. They are generally dark, bu t man y s p ecies are whitish, g reen, or y ellowish, and some are stri p ed or mottled. The bod y is either elon g ate (Arthro p leona) (Fi g ure 5.1B) or more or less g lobular (S y m p h yp leon a and Neeli p leona) (Fi g ure 5.1A). The head is p rimitivel yp ro g nathous, but is h yp o g nathous F I GU RE 5.1. Co ll em b o l a. ( A ) Smint h urus purpurescens ( Sm i nt h ur id ae ) ;an d( B ) E ntomo b rya niva l i s ( Ento - mobr y idae). [Re p rinted from Elliott A. Ma y nard, 1951 , A Monograph o f the Collembola or Springtail Insects o f N ew Yo r k Stat e , Comstoc k Pu bli s hi ng Co., Inc.] 115 A PTERY GO TE H EX A PODS i n the Symphypleona and Neelipleona, and the mouthparts are enclosed within a pouc h formed b y the ventrolateral extension of the head ca p sule. The mouth p arts are t yp icall y o f th ec h ew i n g t yp e, t h ou gh i n man y s p ec i es t h e y are ras pi n g or suctor i a l .T h e 4-se g mente d antennae var yg reat ly i n l en g t h an d eac h se g ment ma yb esu bdi v id e di nto two (se g ments 1 and 2) or numerous (segments 3 and 4) subsegments. Immediately behind the antennae i s a structure of varied form, the postantennal organ, which appears to have an olfactor y function. Com p ound e y es never occur, but a varied number of ocelli (u p to ei g ht) ar e f oun d on eac h s id eo f t h e h ea d .T h et h orac i cse g ments are di st i nct i n Art h ro pl eona, b ut n ot i n Symp h yp l eona an d Nee li p l eona; i na ll spec i es t h e prot h orax i s sma ll or vest i g i a l .I n t he Symphypleona and Neelipleona the thorax is fused with the abdomen and individua l segments are not easily distinguished except at the posterior end. The legs have no true tarsu s but terminate in one or two claws that arise from the tibia. No more than six abdominal se g ments can b e di st i n g u i s h e d at an y t i me (even d ur i n g em b r y on i c d eve l o p ment). T h e first a bd om i na l se g ment b ears t h eco ll o ph ore (ventra l tu b e), w hi c h ar i ses by f us i on an d diff erent i at i on o f t h eem b ryon i c appen d ages. T h etu b e conta i nsapa i ro f ves i c l es t h at ca n b e extruded by hemolymph pressure. The tube appears to have several functions, though it w a s o ri g inall y named because it was thou g ht to be adhesive (Greek colle ,g lue). Other likel y f unct i ons i nc l u d e g aseous exc h an g ean d ,es p ec i a lly ,sa l t-water b a l ance. Most Co ll em b o la h ave a s p r i n gi n g or g an ( f urcu l a) on t h e f ourt h a bd om i na l se g ment, h e ld un d er tens i o n b eneat h t h e b o d y b ya h oo klik e structure, t h e ret i nacu l um, f orme df rom t h e appen d ages o f t he third abdominal segment. When released from the retinaculum, the furcula is forced d ownward and backward by both muscular action and hemolymph pressure. As it strikes th esu b strate, t h ean i ma li st h rown t h rou gh t h ea i r, somet i mesas ig n i ficant di stance (e. g ., up to 30 cm i n some sm i nt h ur id s). A bd om i na l a pp en d a g es ma yb e g reat ly re d uce di n sma ll su b terranean f orms. Cerc i are a b sent i nCo ll em b o l a. Some spec i es are ecomorp hi c, t h e i r form changing from instar to instar as a result of unusual environmental conditions, others a re cyclomorphic (having seasonally different forms and habits, usually in summer and w inter), and some show e p itok y in which re p roductive instars are mor p holo g icall y different f rom non-re p ro d uct i ve ( f ee di n gi nstars) w i t h w hi c h t h e y a l ternate. Notewort h y f eatures o f t h e i nterna l structure o f Co ll em b o l a are t h ea b sence o f Malpighian tubules and, in most species, tracheal system. However, a pair of spiracles b etween the head and thorax, leading to tracheae in the head, sometimes also the body, have b een re p orted for a few S y m p h yp leona. The nervous s y stem is s p ecialized and include s b ra i n, su b eso ph a g ea lg an gli on, an d t h ree ventra lg an gli a, t h e g an gli ao f t h ea bd om i na l se g ments h av i n gf use d w i t h t h e metat h orac i c g an gli on . L if eH i story and Hab i ts Sp r i n g ta il s are a l most u biq u i tous, b e i n gf oun di n high l at i tu d es (e. g ., 8 4 ◦ south i n Antarct i ca) an d a l t i tu d es (a b ove 7700 m i nt h eH i ma l ayas), d eserts, an d g l ac i ers, i na ddi t i o n t o more conventional biomes. Within these regions they occupy a wide range of habitats, t hough they are most abundant and diverse in moist soil, leaf litter, and rotting wood. Other s live in dun g , in the flesh yp arts of fun g i, in the nests of termites, ants, and vertebrates, o n g rasses, an di n fl owers. Severa l s p ec i es occur i n caves, on t h e sur f ace o f stan di n g wate r (i nc l u di n g , rare ly ,t id a lp oo l s), an di n b ot h mar i ne an df res h water i ntert id a l zones, t h ou gh v ery few are truly aquatic. Occasionally, species form large aggregations on the surfac e o f snow, though the significance of this is not clear. Most Collembola cannot tolerate d esiccation, and those that colonize dr y habitats show various mor p holo g ical, p h y siolo g ical , 1 1 6 C H A PTER 5 and behavioral adaptations, such as scales or hairs, specific desiccation-resistant stages (includin g more or less com p letel y dried out “anh y drobiotic” forms), and activit y restricte d to p er i o d sw h en t h ere l at i ve h um idi t yi s high .Co ll em b o l a are sa p ro ph a g ous, f un gi vorous ( i nc l u di n g some s p ore f ee d ers), or phy to ph a g ous ( i nc l u di n g some p o ll en f ee d ers), an d som e species appear to have an intrinsic gut cellulase. Only rarely are they predaceous. Thoug h af ew f f s pecies are occasionally of economic importance because of the damage they cause to p lants, overall Collembola ma y be considered beneficial. B y feedin g on fun g al h yp ha e an dd eca yi n g mater i a l ,t h e y ma yi n fl uence m y corr hi za lg rowt h an d contro lf un g a ldi sease s (Hop ki n, 1997) . In adult Collembola reproductive and feeding instars alternate. Most species of C ollembola reproduce sexually though a few soil-dwelling species are parthenogenetic. Sp erm transfer is usuall y indirect, males p lacin g their stalked s p ermato p hores on the sub - strate, to b e f oun dbyf ema l es as a resu l to f a gg re g at i on ( p er h a p s i nvo l v i n gph eromones) o r a f ter an e l a b orate courts hip d ance i nw hi c h t h ema l e g ras p st h e f ema l eus i n g s pi nes on hi s antennae, h ea d ,or l egs, an dd raws h er over t h e spermatop h ore. T h epa l e, sp h er i ca l eggs ar e l aid singly or in small clusters (sometimes several females oviposit collectively) and may be covered with freshl y eaten soil and fecal material, or cleaned b y the adults, to p revent f un g a li n f ect i on. T h ere i s li tt l ec h an g e i n externa lf orm as t h e y oun g an i ma ld eve l o p s, an d sexual maturit y is reached usuall y after 5–10 molts. As man y as 50 molts ma y occur durin g t h ea d u l tp h ase. P hylo g eny and Classificatio n Accor di ng to Ku k a l ov´a-Pec k (1991), t h e ear l yCo ll em b o l a were sem i aquat i c. T h e earliest fossil collembolan , Rhy nie ll a praecurso r , from the Lower Devonian of Scotlan d resembled modern isotomids. Other fossils are known from the Lower Permian of Sout h Af r i ca, t h eU pp er Cretaceous o f Cana d a, an d Tert i ar y am b er d e p os i ts, t h e l atter b e i n g ass ig na bl e to extant g enera. Current ly ,t h e two most p r i m i t i ve f am ili es are t h ou gh tto b e t h e Hypogastrur id ae an d Isotom id ae, w i t h t h e Entomo b ry id ae an d Sm i nt h ur id ae among t he most advanced. Early classifications [e.g., that of Gisin (1960)] arranged extant species o f the order Collembola in two suborders, Arthropleona and Symphypleona, principall y o nt h e b as i so f t h e str iki n g diff erence i n b o dy f orm, an d five f am ili es. Nowa d a y s, u p to 1 4 f am ili es are reco g n i ze d ,an d t h ese are a ll ocate d amon g t h ree or d ers w i t hi nt h ec l as s C o ll em b o l a, t h e roun d - b o di e d Nee lid ae b e i ng separate df rom t h e Art h rop l eona i nt h e i r o w n order Neelipleona. However, lack of information prevents the construction of a phylo - genetic tree. Of the extant families, the largest and most common are the Hypogastruridae , N eanuridae, On y chiuridae, Entomobr y idae, Isotomidae, and Sminthuridae . Order Arthropleona S uperfamily Poduroidea T he HYPOGASTRURIDAE ( 5 80 species) are generally 1–3 mm in length, whitish, p inkish, or darkl y colored Collembola with a p redominantl y holarctic distribution. The y h aveano b v i ous p rot h orax, a g ranu l ar cut i c l e, an d s h ort antennae, b ut a p ostantenna l or g a n may or may not b e present. T h ey are f oun di naw id e range o fh a bi tats t h oug h most spec i es l ive among decaying vegetation, in soil, in cracks in the bark of trees, or in fungi. Some hypogastrurids are known as “snow fleas” through their being found, sometimes in immens e 117 A PTERY GO TE H EX A PODS n umbers, jumping about on snow, usually shortly after a period of mild weather. One widely d istributed form , Hypogastrura (Ceratophysella) denticulata ( likel y a com p lex of severa l s p ec i es), somet i mes b ecomes a p est i n mus h room ce ll ars. T h ema j or i t y o f NEANURIDAE (11 6 0s p ec i es) are f oun d un d er stones an db ar k ,or i n soil and leaf litter where they feed on fungal hyphae that they pierce with their shar p m outhparts. Other species, however, are predaceous, eating rotifers, other Collembola, and t heir e gg s. ONYCHIURIDAE (600 s p ecies) are soil- and litter-dwellin g collembolans tha t l ac k oce lli an d a f urcu l a . Superfamily Entomobryoidea The characteristics of the ISOTOMIDAE (over 1000 species) are highly varied, and future work may well result in its beingsubdivided into several additionalfamilies. Isotomids are found worldwide, in a ran g e of biomes, includin g the p olar re g ions, arid areas, and seas h ores, t h ou gh man y are convent i ona li n h a bi tants o f so il or l ea fli tter. Man y s p ec i es, e s p ec i a lly t h eso il d we ll ers, are cosmo p o li tan. T h e f am ily ENTOMOBRYIDAE (F ig ure 5 .1B), with 136 5 species, includes many of the larger Collembola that reach 5 mm or more i n length. Species have a greatly reduced prothorax and a smooth cuticle; a postantenna l or g an ma y or ma y not be p resent. The y ma y be found in soil or leaf litter, under bark, i n m oss, an d on ve g etat i on. Some s p ec i es are natura lly cosmo p o li tan, an d ot h ers h ave b ee n t rans f erre d aroun d t h ewor ld by h uman act i v i t y. Order Neeli p leona The approximately 2 5 species in this order are included in a single family NEELIDAE . These tiny collembolans (0. 5 mm or less long) live in soil and leaf litter. They differ from S y m p h yp leona in that their rounded bod y is formed from ex p ansion of thoracic rather tha n a bd om i na l se g ments. Order Symphypleon a Superfami l y Smint h uroi d ea M ost of the 890 species of SMINTHURIDAE (Figure 5 .1A) are 1–3 mm in length and h ave a roundish body, hypognathous head, and conspicuous ocelli. A postantennal orga n i s absent. Often there is sexual dimorphism, with the antennae of males having hooks and s p ines. Most sminthurids are e p i g aeic, livin g near the surface of leaf litter, or on g rasses o r ot h er l ow- g row i n g ve g etat i on. A num b er o f s p ec i es are econom i ca lly i m p ortant. For exam- pl e, S mint h urus v iri d i s ,t h e l ucerne fl ea, a Euro p ean s p ec i es i ntro d uce di nto Austra li a, h as b ecome an important pest on alfalfa (lucerne) andother leguminous crops. Other speciesmay d o considerable damage in greenhouses and to many garden vegetables at the seedling stage. L i t e r a t u r e Accounts of the biolo gy of Collembola are p rovided b y F j ellber g (1985), Greenslad e ( 1991, 1994), Ho pki n (1997), an d C h r i st i ansen an d Be lli n g er (1998). Ke y s f or t h e ir i dentification are to be found in Christiansen and Bellinger (1998) [North American species] , G isin (1960) [European species] (in German), and Greenslade (1991) [Australian families]. 118 C H A PTER 5 Christiansen, K., and Bellin g er, P., 1998, The Collembola o f North America North o f the Rio Grande , 2nd ed., G r i nne ll Co ll ege, Gr i nne ll , IA. F j ellber g , A., 198 5 , Recent advances and future needs in the stud y of Collembola biolo gy and s y stematics , Q uaest . E n to m ol. 2 1:55 9 –570. Gi s i n, H., 19 6 0 , C o ll em b o l enfauna Europas , Museum d ’ hi sto i re nature ll e, Geneva. G reens l a d e , P. , 1994 , Co ll em b o l a ,i n: Zoo l ogica l Cata l ogue of Austra l i a ,V ol. 22 (W. W. K. Houston, ed.), CSIRO, V V Melbourne . G reens l a d e, P. J., 1991, Co ll em b o l a, i n : Th e Insects of Austra l i a ,2n d e d ., Vo l . I (CSIRO, e d .), Me lb ourne Un i vers i t y Press , Car l ton , V i ctor i a . H opkin, S. P., 1997 , Biology o f the Springtails (Insecta: Collembola) , Oxford University Press, Oxford. K u k a l ov´a-Pec k , J., 1991, Foss il hi story an d t h eevo l ut i on o fh exapo d structures, i n : T h e Insects of Austra l ia,2n d ed ., Vo l . I (CS l RO, e d .), Me lb ourne Un i vers i t y Press, Car l ton, V i ctor i a. 3 .Pr o t u r a S ynonym: M y rientomat a C ommon name: p ro t uran s Minute wingless hexapods; head cone-shaped, compound eyes, ocelli, and antennae ab- sent, mout h parts entognat h ous an d suctor i a l ; f ore l eg mo di fie d as a sense organ; a bd ome n 1 2-se g mented in adult with a pp enda g es on first three se g ments; g ono p ore (two in males) behind 1 1t h segment; cerc i a b sent . About 660 s p ecies of p roturans have been described worldwide. Of these, about 80 are Euro p ean ( i nc l u di n g 20 i nBr i ta i n), 30 Austra li an, an d a b out 20 Nort h Amer i can, t h ou gh t h e l atter fi g ure ma yb em i s l ea di n g ,re fl ect i n g t h e l ac k o f taxonom i cwor kd one on t hi s g rou p. S tructur e P roturans (Fi g ure 5.2) are elon g ate, g enerall yp ale arthro p ods 2 mm or less in len g th . Th e h ea di s cone-s h ape d an db ears anter i or l yt h e sty lif orm entognat h ous mout h parts. P h o- toreceptor organs are absent from the head, as are typical antennae. However, a pair o f “ p seudoculi” occur dorsolaterall y that ma y be humidit y rece p tors or chemosensor y . The t h orac i cse g ments are di st i nct, t h ou gh t h e first i s g reat ly re d uce d .T h es i x id ent i ca ll e g s h ave an unse g mente d tarsus. T h e f ore l e g s are g enera lly not use di n l ocomot i on b ut are h e ld a l o ft FI GU RE 5.2 . Ace r ella ba r be r i ,a p roturan. [From H. E. Ewin g , 1940, The Protura of North America , A nn. Entomol. Soc. Am. 33 : 495–551. By permission of the Entomologica l S oc i et y o f Amer i ca.] 119 A PTERY GO TE H EX A PODS and probably act as sense organs. In adult proturans the abdomen is 12-segmented; in th e n ewl y hatched animal there are onl y 9 abdominal se g ments, 3 bein g added anamor p hicall y d ur i n gp ostem b r y on i c d eve l o p ment. S h ort, unse g mente d or 2-se g mente d a pp en d a g es w i t h ev e rs ibl eves i c l es are f oun d on t h e first t h ree a bd om i na l se g ments. Cerc i are a b sent . I nternally there are no distinct Malpighian tubules, but six papillae occur at the junction o f the midgut and hindgut, and these may serve an excretory function. A tracheal system is p resent in Eosentomoidea, ori g inatin g from p aired meso- and metater g al s p iracles, but no t i not h er g rou p s. T h e trac h eae d o not anastomose. T h e nervous s y stem i s g enera li ze d ,w i t h di screte gang li a i nt h e first seven a bd om i na l segments . Life Histor y and Habits Like springtails, proturans are found in a variety of moist habitats. Although frequently ov e rlooked because of their small size, the y are q uite numerous in certain situations p ar - ti cu l ar ly i nso il an dli tter. Few d eta il so f t h e i r bi o l o gy are ava il a bl e. T h e y are t h ou gh tto b e f un gi vorous. It i sre p orte d t h at f our j uven il e sta g es are p asse d t h rou gh b e f ore sexua l m aturity is reached (five in male Acerentomidae which have a preimago instar), but it is n ot known whether proturans molt when adult. There are probably several generations per y ear with, in cooler climates, the adults s p endin g the winter in a dormant condition. Phylo g eny and C lass ifi cat i on Tu x e n ( 19 6 4) reco g n i ze d two su b or d ers an d t h ree f am ili es w i t hi nt h ec l ass an d or - d er Protura, name ly ,t h e Eosentomo id ea ( f am ily EOSENTOMIDAE) an d Acerentomo id e a (f am ili es ACERENTOMIDAE an d PROTENTOMIDAE). However, f o ll ow i ng t h e d e- scription of S inentomon er y t h ranum b y Yin (196 5 ), which shows morphological fea - t ures of all three families and ma y be the most p rimitive livin gp roturan, some authors ( e. g ., Nose k , 1973) h ave pl ace d t hi ss p ec i es i n i ts own su b or d er S i nentomo id ea ( f am ily SINENTOMIDAE). T h ou gh most wor k ers cons id er t h e Eosentom id ae an d S i nentom id ae as t h e most pr i m i t i ve proturans, t h e i r possess i on o f a trac h ea l system an d certa i n f eature s of their sperm have led Yin (1984) to propose that they are more specialized than the Acerentomoidea . L i t e r a t u r e M ost li terature on Protura i s taxonom i c. Accounts o f t h e bi o l o gy o f t hi s g rou p are gi ve n by Ew i n g (1940), Nose k (1973), an d Im id at´e (1991). Nose k (1973) p rov id es a k e y to t h e E uropean spec i es an d Nose k (1978) a k ey to t h ewor ld genera; Ew i ng (1940) d ea l sw i t h t h e N orth American forms; and Imidat´e ( 1991 ) with the Australian families . E wing, H. E., 1940, The Protura of North America , Ann. Entomol. S oc. Am . 33 : 4 9 5–551 . Im id at´e, G., 1991, Protura, i n : Th e Insects of Austra l ia , 2n d e d ., Vo l . I (CSIRO, e d .), Me lb ourne Un i vers i ty Press, Car l ton , V i ctor i a. N osek, J., 1973 , The Euro p ean Protur a , M u seum d’histoire naturelle, Geneva . N ose k , J., 1978, Key an ddi agnos i so f Protura genera o f t h ewor ld , Annot. Zoo l . Bot. Bratis l av a 122 :1–59. T uxen , S. L. , 19 6 4 , Th e Protura. A Revision of t h e Species of t h eWor ld wit h Keys for Determination , Hermann , Par i s. Yin, W Y., 1965, Studies on Chinese Protura. II. A new family of the suborder Eosentomoidea, Acta En to m ol. S in. 14 :186–195. (In Chinese with English summary.) Y in, W Y., 1984, A new idea on phylogeny of Protura with approach to its origin and position, YY S ci. Sin. ( B ) 2 7:149–160. 120 C H A PTER 5 4 . Diplur a S ynonyms : Dicellura, Entotro p hi, Ento g nath a C ommon name : d i p luran s Elongate apterygotes; head with long many-segmented antennae, compound eyes, and ocelli ab sent, mout h parts entognat h ous; t h orac i c segments di st i nct, l egs w i t h unsegmente d tarsus; a b - d omen 10-se g mented, most p re g enital se g ments with st y li, eversible vesicles on some abdomina l segments, cerc i present as e i t h er l ong mu l t i annu l ate or f orceps lik e structures, gonopore b etween se g ments 8 an d 9. More t h an 800 s p ec i es o f t hi sw id e ly di str ib ute d ,t h ou gh ma i n ly tro pi ca l or su b tro pi ca l , o r d er h ave b een d escr ib e d . Most h o l arct i c f orms b e l on g to t h e f am ily Cam p o d e id ae, i nc l u d- i ng t h e11Br i t i s h spec i es. Just over 6 0 spec i es h ave b een d escr ib e df rom Nort h Amer i ca, and about 30 from Australia. S tructur e In g eneral form Di p lura (Fi g ure 5 .3) resemble Th y sanura but differ in bein g ento g- nathous and lacking a median process on the last abdominal segment. Most species are a f ew millimeters long, but a few may reach almost 60 mm. The roundish or oval head carrie s the multise g mented antennae, whose fla g ellar se g ments (exce p t the most distal) are p ro- vid e d w i t h musc l es. T h ere d uce dbi t i n g mout hp arts occu py a p ouc h on t h e ventra l sur f ace. Th es i x id ent i ca ll e g s h ave an unse g mente d tarsus. Two to f our l atera l s pi rac l es occur on t he thorax. Ten abdominal segments are distinguishable. The sterna of segments 2–7 bear styli , and eversible vesicles occur on a varied number of segments. The conspicuous cerci vary in structure and are an im p ortant taxonomic feature. In most Di p lura (but not Cam p odeidae, whi c hh ave none) t h ere are seven p a i rs o f a bd om i na l s pi rac l es. F IGURE 5.3. Di p l ura. (A) Cam p odea s p. (Campo d e id ae); (B) Anajapyx vesiculosus ( Ana j apyg id ae); an d ( C ) H etero j apyx sp . (Hetero j a pyg idae). [From A. D. Imms, 19 5 7, A Genera l Text b oo k of Entomo l ogy , 9t h e d . (revised b y O. W. Richards and R. G. Davies), Methuen and Co. ] 121 A PTERY GO TE H EX A PODS As in Protura, Malpighian tubules are represented usually by a varied number of papilla e at the j unction of the mid g ut and hind g ut. The tracheal s y stem is develo p ed to a varied extent. Trac h eae l ea di n gf rom one s pi rac l e never anastomose w i t h t h ose f rom ot h er s pi rac l es, an d th e yl ac k cut i cu l ar su pp ort i n g r i n g sc h aracter i st i co fi nsectan trac h eae. T h e nervous s y stem is n ot specialized, the ventral nerve cord containing eight (Japygidae) or seven (other Diplura ) abdominal ganglia. The reproductive system is greatly varied within the Diplura, although i n all s p ecies the g ermaria are a p ical. I n J apyx ( Ja pyg idae) there are seven p airs of se g mentall y arran g e d ovar i o l es, i n A na j apyx (Ana j a pygid ae) two, an din C ampode a ( Cam p o d e id ae) one . One or two pa i rs o f testes occur i nt h ema l e. Life Histor y and Habits Because o f t h e i r rat h er secret i ve h a bi ts li tt l e i s k nown o f t h e lif e hi story o fdi p l urans. They are found in damp habitats, for example, leaf litter, under stones and logs, and in soil . The cam p odeids are herbivorous, but other Di p lura are carnivorous, catchin gp re y with th e i r f orce p s (mo di fie d cerc i )orw i t h t h e i r max ill ae. L ik ema l es p r i n g ta il s, ma l e dipl urans d e p os i t sta lk e d s p ermato ph ores b ut ma k e no attem p t to attract f ema l es to t h em. T h ee ggs a re l a id i n groups i nac h am b er d ug b yt h e f ema l e. In some spec i es t h e f ema l e guar d st h e e ggs and young. Development is slow and molting (up to 30 times in Cam p o d ea ) continues t hrou g h life . Phylogeny and C lass ifi cat i on Fossil Di p lura are known from the U pp er Carboniferous of Illinois ( T estajapyx thomas i ) th ou gh at t hi s sta g et h ea pp en d a g es were st ill f u lly se g mente d ,e y es were p resent, an d t h e e ntognat h ous con di t i on was not f u ll y d eve l ope d ;t h at i s, t h e l atera l marg i ns o f t h e h ea d were not fused with the labium to form a pouch around the mandibles and maxillae. Extan t Diplura were arranged by Paclt (19 5 7) in three families [CAMPODEIDAE, PROJAPY - G ID A E ( = A NAJAPYGIDAE ) , and JAPYGIDAE]. However, more recent classifications [e. g ., t h at o f Con d ´ean d Pa g ´es (1991)] ten d to ra i se t h esu bf am ili es w i t hi nt h ese g rou p sto t he rank of famil y .Incam p odeids (Fi g ure 5 .3A), which ma y reach 4 mm at maturit y , the cerci are multiannulate and usually as long as the abdomen. In contrast, the projapygids ( Figure 5 .3B) are minute arthropods with relatively short cerci (less than half the length o f t he abdomen and havin g fewer than 10 subdivisions). The cerci of j a pyg ids (in the sense of Paclt, 1957) take the form of stron g l y sclerotized, undivided force p s (Fi g ure 5.3C) . L i t e r a t u r e G enera li n f ormat i on on D ipl ura i s gi ven by Wa ll wor k (1970) an d Con d ´ean d Pa g ´es ( 1991). Most Nort h Amer i can spec i es can b e id ent i fie df rom Sm i t h (19 6 0), t h eBr i t i s h species from Delany (19 5 4), and the Australian families from Cond´e and Pag´es (1991) . Cond´e, B., and Pag´es, J., 1991, Diplura, in: T he Insects o f Australi a , 2nd ed., Vol. I (CSIRO, ed.), Melbourne U n i vers i t y Press, Car l ton, V i ctor i a . Delan y , M. J., 19 5 4, Th y sanura and Di p lura , R. Entomol. S oc. Handb. Ident. Br. Insects 1 ( 2 ) :1–7. P aclt, J.,1957, Diplura, G enera Insect. 212 :1 – 123. S m i t h , L. M., 19 6 0, T h e f am ily Pro j a pygid ae an d Ana j a pygid ae (D ipl ura) i n Nort h Amer i ca , A nn. Entomo l . Soc . A m . 5 3 :575 – 583. W allwork, J. A., 1970 , Ecology o f Soil Animals ,M c Graw-Hill, New York . 122 C H A PTER 5 5. Microcoryphia Synonyms : A rc h eo g nat h a, Ectotro phi ( i n p art) , C ommon name: b r istletails E cto g natha (in p art) Small or moderately sized apterygote insects; head with long multiannulate antennae, large c ont ig uous com p oun d e y es, oce lli , ecto g nat h ous c h ew i n g mout hp arts, man dibl es w i t h s i n gl ear- ticulation, maxillar yp al p s 7-se g mented; thorax stron g l y arched with ter g a extendin g over p leura , l egs w i t h 3 (rare l y 2) tarsa l segments; a bd omen 11-segmente d ,t h oug h 10t h segment re d uce d an d ter g um o f 11t hf orm i n g me di an cau d a l fi l ament, p a i re d st yli p resent on eac h a bd om i na l se g ment , long cerci with multiple subdivisions present. As note di nt h e Intro d uct i on to t hi sc h a p ter, M i crocor yphi aan d Z yg entoma (see Sect i o n 6 ) were or igi na lly un i te di nt h eor d er T hy sanura. However, f un d amenta l diff erences i nt h e ir structure (compare t h e d efin i t i ons o f t h eor d ers) h ave l e d to t h e i r separat i on as di st i nct o rders. The Microcoryphia form a small (about 3 5 0 species) but cosmopolitan group, wit h about 35 s p ecies in North America (mostl y Machilidae), 7 in Australia (all Meinertellidae), an d 7 i nBr i ta i n(a ll Mac hilid ae) . Structur e Microcoryphia (Figure 5 .4A) are elongate insects up to 20 mm in length. Their body i s strongly convex dorsally (with the large terga extending around the sides to cover the pleura) , g enerall y ta p ered p osteriorl y , and covered with scales. The head is h yp o g nathous, in som e s p ec i es p ro g nat h ous, an d carr i es p rom i nent c h ew i n g mout hp arts, t h e l on g , 7-se g mente d max ill ar yp a lp s b e i n gp art i cu l ar ly cons pi cuous. Eac h man dibl e h as a s i n gl e art i cu l at i on w i t h t h e h ea d .T h e antennae are fi lif orm an d compr i se 30 or more su bdi v i s i ons t h at l ac ki ntr i ns ic musculature. Compound eyes are well developed and contiguous (meet in a middorsa l p osition). Median and paired lateral ocelli are also present. The legs have three tarsal se g ments an d , i n some s p ec i es, t h ose o f t h e mesot h orax an d metat h orax b ear coxa l st yli . Abd om i na l st yli occur on se g ments 2–9, an d evers ibl eves i c l es are a l most a l wa y s f oun d o na bd om i na l segments 1–7. In f ema l es an ov i pos i tor i s f orme df rom t h e appen d ages o f ( Machil- e d from ni vers i t y , 9th ed . [...]... small or absent, ocelli absent (except Lepidotrichidae), ectognathous chewing mouthparts, mandible with dicondylic articulation, maxillary palp 5- segmented; legs with 2–4 tarsal segments; abdomen 11-segmented but with 10th segment 123 APTERYGOTE HEXAPODS 124 CHAPTER 5 reduced and tergum of 11th segment forming median caudal filament, paired styli on abdominal segments 7–9 (rarely 2–9), cerci generally long... are provided by Delaney (1 957 ) and Sharov (1966) Keys for identification are given in the papers by Delany (1 954 ) [British species], Wygodzinsky (1972) [North and Central American Lepismatidae], and Wygodzinsky and Schmidt (1980) [Microcoryphia of eastern North America] Delany, M J., 1 954 , Thysanura and Diplura, R Entomol Soc Handb Ident Br Insects 1(2):1–7 Delany, M J., 1 957 , Life histories in the Thysanura,... (both Lepismatidae) Structure Zygentoma (Figure 5. 4B) are broadly similar to Microcoryphia, and only the more important differences in structure will be noted here The body of Zygentoma is dorsoventrally flattened and may or may not have scales Compound eyes are reduced or absent and ocelli do not occur (except in Lepidotrichidae) The maxillary palps are 5- segmented, and the mandibles have a dicondylic... Lepidotrichidae (Thysanura), Ann Entomol Soc Am 54 :621–627 W Wygodzinsky, P., 1972, A review of the silverfish (Lepismatidae, Thysanura) of the United States and the Caribbean Area, Am Mus Novit 2481:26 Wygodzinsky, P., and Schmidt, K., 1980, Survey of the Microcoryphia (Insecta) of the northeastern United States and adjacent provinces of Canada, Am Mus Novit 2701:17 1 25 APTERYGOTE HEXAPODS ... absent in many Lepismatidae but occur on abdominal segments 2–7 in Nicoletiidae and Lepidotrichidae In most species the cerci are long, multiannulate structures that diverge sharply from the body (Figure 5. 4B) However, in some inquiline Nicoletiidae the cerci are very short Four to eight Malpighian tubules are present Ten pairs of spiracles occur and the tracheal system is well developed compared to that . Nort h Amer i ca , A nn. Entomo l . Soc . A m . 5 3 :57 5 – 58 3. W allwork, J. A., 1970 , Ecology o f Soil Animals ,M c Graw-Hill, New York . 122 C H A PTER 5 5. Microcoryphia Synonyms : A rc h eo g nat h a,. various mor p holo g ical, p h y siolo g ical , 1 1 6 C H A PTER 5 and behavioral adaptations, such as scales or hairs, speci c desiccation-resistant stages (includin g more or less com p letel y dried. aquatic. Occasionally, species form large aggregations on the surfac e o f snow, though the significance of this is not clear. Most Collembola cannot tolerate d esiccation, and those that colonize