Lepidodasypus sharovi n. gen., n. sp. is distinguished from previously described species of Dasyleptus by the fine vestiture of scales and hairs, by the heavier pigmentation of the tergites, and by the shorter first maxillary palpi. Preservation of the unique type specimen shows well the presence of segmented abdominal legs, and their posterior specialization to form an ovipositor of ovigerous legs. This is the first record of a dasyleptid monuran from North America and is the oldest representative of the order Thysanura on this continent.Texas Memorial Museu

Durden, Christopher J.

English

Texas ScholarWorks

THEPEARCE-SELLARDS ScfieSNUMBER 30A DASYLEPTID FROM THE PERMIAN OF KANSAS,LEPIDODASYPUS SHAROVI N. GEN., N. SP.(INSECTA: THYSANURA: MONURA)Christopher J. Durden1978Texas Memorial Museum/2400 Trinity/Austin, Texas 78705W. W. Newcomb, DirectorThe Pearce-Sellards Series is an occasional, miscellaneous series ofbrief reports of museum and museum associated field investigationsand other research. Its title seeks to commemorate the first twodirectors of the Texas Memorial Museum, both now deceased:J. E. Pearce and Dr. E. H. Sellards, professors of anthropology andgeology respectively, of The University of Texas.A complete list of Pearce-Sellards papers, as well as other publica-tions of the museum, will be sent upon request.1A DASYLEPTID FROM THE PERMIAN OF KANSASLEPIDODASYPUS SHAROVI N. GEN., N. SP.(INSECTA: THYSANURA: MONURA) 1Christopher J. Durden 2ABSTRACTLepidodasypus sharovi n. gen., n. sp. is distinguished from previouslydescribed species of Dasyleptus by the fine vestiture of scales and hairs,by the heavier pigmentation of the tergites, and by the shorter first maxil-lary palpi. Preservation of the unique type specimen shows well the presenceof segmented abdominal legs, and their posterior specialization to form anovipositor of ovigerous legs. This is the first record of a dasyleptid monuranfrom North America and is the oldest representative of the order Thysanuraon this continent.INTRODUCTIONWhile examining specimens in the Dunbar collection of Kansas PermianInsects in Yale Peabody Museum of Natural History, the author found aspecimen of a Dasyleptus- like insect among material that had been labeledby R. J, Tillyard as “nymph of cockroach.” As Dasyleptus figures promi-nently in recent discussions (Tiegs and Manton 1958; Sharov 1966) of theearly evolution of insects, as this specimen shows structures of the ventralabdomen more clearly than does most previously known material, and asthe family has previously not been known from North America, this speci-men is described here. Comparison of this specimen with material from thePermian of the USSR (Kuznetsk Basin) shows differences of generic impor-tance. Unfortunately, the description of D. lucasi, the type of the genus, isnot detailed enough for clear comparison with this older species from theStephanian of France (Commentry).Lepidodasypus new genus(Type species: L. sharovi n. sp.)This genus includes Machilis-like insects characterized by segmenta-tion of the abdominal parapodia or styli-like legs, and the shortness andfive-segmentation of the thoracic legs which bear a prominent single termi-nal claw and lack a clearly differentiated functional knee. The antennaeare apparently short, the compound eyes are large and form most of theposterior part of the head. The labrum is strong and is articulated with1 Accepted for publication November 23, 19772Xexas Memorial Museum, 2400 Trinity Street, Austin, Texas 787052the clypeus. The mouthparts, although poorly preserved, appear to includechewing mandibles and maxillae, and five-to possibly seven-segmented maxil-lary palpi. The labium bears a robust postmentum which covers the posteriorlateroventral comer of the head. The cardo is smaller than the postmentum,and lies anterior to it, against the ocular region of the acron. The prothoracictergum is smaller than the other body terga, and is not expanded anteriorlyover the head. Except for an abrupt increase in size of the thoracic legs, thethorax is differentiated from the abdomen only by gradient shift in charac-ters, beginning in the anterior abdomen. The terga are divided into lateralpaired tergites by the mid-dorsal suture. The thoracic leg consists of claw,tarsus, tibia, femur, and trochanter, which articulate basally against at leasttwo obscure lateral coxites, which are plates of the body wall. The articula-tory condyle of the leg appears to be lateral, with the trochanter directedtoward the ventral midline. The femuro-trochanteral articulation is acute,with the femur and the remainder of the leg directed laterally. The simplekneeless conical leg is of a kind that has been associated with aquatic lifein such scorpions as Palaeophonus (Silurian). In small arthropods under fivemillimeters in length, however, this leg form is found in many terrestrialgroups of crawling gait, such as the Pauropoda, Pselaphognatha, Protura, andsome mites. Hence Lepidodasypus need not have been aquatic. The presenceof hairs and scales strongly suggests a terrestrial habit. An ovipositor is pres-ent and is formed by specialization of the abdominal legs (stylets) seven andeight to form ovigerous legs, and by appendages of the ninth and probablytenth abdominal segments. The homology of these latter two segmentalappendages is not definitely known, for although the analogous structuresin modem Thysanura are formed from homologues of exsertile vesicles, inthe Dasyleptidae they are apparently leg (styli) homologues, for no abdomi-nal legs are known on abdominal segments nine and ten in any specimensof Dasyleptus or Lepidodasypus. Spiracles are present on the pleural mem-brane on at least the first eight abdominal segments and on the metathorax.From impressions and maculae (muscle scars), the body musculature and thethoracic musculature appear to pass from abdominal configuration to tho-racic configuration by a gradient change across the first abdominal segment.Maculae of the trunk tergites, the sites of muscle attachment, lie in threeprominent longitudinal series. Dorsal maculae occur on the thoracic tergaand on the first two abdominal terga, and are largest on the metanotum.Dorsolateral maculae lie in a line which curves laterally on the first andsecond abdominal terga, to enter the thorax. The dorsolateral maculaeof the pronotum are minute or absent. Lateral maculae border the abdomi-nal terga, are largest in the first, second, and third abdominal segments andreniform on the thoracic terga. The terga, legs, and maxillary palpi areclothed with a vestiture of articulated hairs and scales, those of the legsbeing very fine. Dasyleptus lucasi Brongniart, 1885, the type species of thatgenus, from the Stephanian A (Upper Carboniferous) of Commentry, Allier,France, was briefly described without figure. Brongniart’s type material was3apparently used by Handlirsch for his figure (1908) of this insect, but thismaterial has not been described since. Sharov was of the opinion (pers.comm. 1967) that the presence of scales and the more fully segmented ab-dominal legs (styli) are characters sufficient for generic distinction of theAmerican species. Analogous characters are of generic significance in somemodem Thysanura.Lepidodasypus sharovi new speciesHOLOTYPE: Figs. 1,2, 3; YPM 28152, originally bearing a typewritten “i”paper tag, and thus part of the Tillyard loan. The reverse portion of thisspecimen was not found in the collection at Yale and presumably was lostat the collecting site.TYPE LOCALITY: Kansas, Dickinson County, three miles south, one-halfmile east of Elmo at “Insect Hill.” This is the locality “Banner City” dis-covered to contain plants by Charles Sterling before 1900, and to containinsects by E. H. Sellards in 1902. This specimen was collected by CarlDunbar in 1921.TYPE HORIZON; Sumner Group, Wellington Formation, Carleton Lime-stone Member of R. C. Moore (1936), Elmo Limestone of C. O. Dunbar(1924).AGE: Permian, late Artinskian (medial Leonardian) Epoch; about 260 Ma.This specimen consists of the head and first 11 body segments, fragmen-tary appendages including parts of the antennae, first maxillary palpi, tho-racic legs one to three and abdominal legs (styli) one to eight. It is pre-served as the internal aspect of the left side, cuticle and residual membraneon white clay-rich limestone. The head is badly crushed, the terga are splitalong the mid-dorsal suture, and most of the twelfth and thirteenth tmnkterga are missing, as is also the caudal region.DescriptionThis species differs from Dasyleptus brogniarti Sharov, 1957, in the moreheavily pigmented tergites, in the broadening of some of the body hairs toform scales, and in the relatively shorter first maxillary palpi, the three dis-tal segments of which when taken together, are shorter than the combinedlength of head and thoracic terga.The holotype is an adult female. It is of machiliform shape, with a poorlydifferentiated thorax, robust head, prominent maxillary palpi, short butsegmented abdominal legs, and paired abdominal coxosternites. The bodylength without the caudal filament is by extrapolative reconstruction, aboutfive millimeters. The body was apparently higher than wide, and was prob-ably less than one millimeter high before lateral crushing. The trunk tergaare more heavily sclerotized than the remainder of the integument, and are4Fig. 1.—Lepidodasypus sharovi n. gen., n. sp., interpretive drawing of the holotype. A - antenna,ACI to ACS - abdominal coxosternites 1 to 8, ALI to AL6 - abdominal legs or styli 1 to 6, AL7& ALB - first and second ovigerous legs, AL9 - valve of ovipositor, ATI to AT9 - abdominal terga1 to 9, AT 10 & AT 11 - presumed location of abdominal tergites 10 and ll,iC - presumed locationof caudal filament, CXI to CX3 - prothoracic, mesothoracic, and metathoracic coxites, DLM - dorso-lateral macula, DM - dorsal macula, E - compound eye, LI to L 3 - thoracic legs, LM - lateral macula,MX - first maxilla, SP3 - metathoracic spiracle, SP4 to SPII - abdominal spiracles of abdominal seg-ments 1 to 8, THI to TH3 - thoracic terga, the pronotum, mesonotum, and metanotum.5well pigmented. The terga and first maxillary palpi are clothed with flathairs, some of which are expanded distally to form narrow scales.The head is robust, with prominent, small-faceted compound eyes whichoccupy the dorsal half of the head. Seven anelli of the antennal flagellumare preserved near its base, and each bears, on the ventral side, a small fixedspine. The clypeus is arched and subtends a prominent labrum. The pre-mandibular appendage (postantennal palp) cannot be recognized and themandibles are poorly preserved but do bear a strongly denticulate molarium.The first maxilla is crushed, with its gnathal elements not clearly identifiable.The first maxillary palpi are more than five, probably as much as seven-seg-mented. The basal three segments are crushed in the right palp and the basaltwo segments are missing in the left palp. The distal three segments areelongate and are covered with a vestiture of very regularly inserted articulatehairs and narrow scales. These decrease in size apically and in places arerubbed off. The distal segment is terminated by a minute claw or hair tuft.The mid segment is short and forms the prominent knee of the appendage.The distal of the three basal segments is also clothed with articulated hairswhich are robust in the dorsal apical region; the two basal segments are ap-parently bald. Details of the stipes cannot be made out but the cardo is smalland lies against the eye, anterior to the postmentum. Details of the secondmaxillae are obscured by the trochanter of the first leg, but a prementum isvisible apically. The tergal element of the segment, the postmentum, formsthe posterior ventrolateral cover of the head, below and behind the lowerpart of the compound eye.The first three trunk segments are little differentiated from the otherbody segments, chiefly by the larger size of the legs. The legs are simple-conical and are laterally directed. To close the trochanteral articulatorycavity, the legs must have been acutely flexed off the trochanter. The tro-chanter articulates laterally against at least two coxal sclerites. The metano-tum is the largest tergum and the pronotum is the smallest of the trunkterga. The pronotum is not expanded anteriorly to cover the side of the head.The abdomen is widest at its fourth segment, from which it tapers inwidth, gently anteriorly and posteriorly. The abdominal terga are separatedby the mid-dorsal suture into lateral plates. The first abdominal legs areminute, with only three segments visible. The second abdominal legs areclearly four-segmented and are the largest of the anterior abdominal appen-dages. Leg length decreases from the second to the sixth abdominal ap-pendage. The seventh abdominal leg is four-segmented, narrow, and is at-tenuated so that the apical segment lies under the presumed tenth abdominalsegment. The eighth abdominal leg is clearly three-segmented, the apical seg-ment being more heavily sclerotized, attenuated and blade-like. The reducedsegment number is probably derived from a fusion of two primary distalsegments, suggesting specialization toward its homologue, the “ventral”valve of pterygote insects. The ovigerous function of the homologues of thestyli has been reported for machilids by Delany (1959) and Sharov (1966),6Fig.2.—Lepidodasypussharovin.gen.,n,sp.,holotypeYPM28152,internalaspectofleftside,photographeddry,withverticalillumination,50mmobjective,30secondexposureonPanatomic-X35mmfilm.Barscaleisonemm.7The presumed ninth abdominal appendage is a posteriorly directed spatula,with a longitudinal groove in its ventral half. This appears to be merely agroove in a simple plate rather than a suture between valvae of the ninth(dorsal part) and eighth (ventral part) abdominal segments as suggested bySharov (pers. comm. 1967). Of course, this structure may have originatedFig. 3 .—Lepidodasypus sharovi n. gen., n. sp., interpretive drawing of head and legs of holotype.A - an ellus, AC - articulatory condyle of the leg, AF - antennal flagellum, C - clypeus, CD - cardo,CL - claw, E - compound eye, F - femur, LBR - labrum, MD - mandible, MP3 - third segment of maxil-lary palp, MP4 - fourth segment of maxillary palp, the functional knee of this appendage, MPS toMP7 - fifth to seventh segments of maxillary palp, MXG - gnathal element of first maxilla, PRM -prementum, PTM - postmentum, TB - tibia, TR - trochanter, TS - tarsus.as two such valvae, and have subsequently fused. The ninth abdominal ap-pendage may represent the external or “dorsal” valve of an ovipositor. Thisdevelopment of the posterior abdominal legs and the extension of the ninthabdominal tergite pleurally, suggests that the structure so formed is an ovi-positor, and that the specimen is a mature female. The abdominal coxo-sternites are largest at abdominal segment four, from which they taper insize both anteriorly and posteriorly. The spiracles are largest on the meta-thorax, and decrease in size posteriorly, and are set in the pleural membrane.DiscussionSharov (1957) proposed a new order, Monura, for the genus Dasyleptus.This action has been questioned by other specialists of apterous insects8(Tuxen 1960, Wygodzinsky pers. comm. 1967) who suggest that Dasyleptusis probably a machiloid thysanuran. Others would remove the group entirelyfrom the insects. The segmented abdominal legs, as pointed out by Sharov(1966) and confirmed here, the lack of tarsal subsegmentation, the weakdifferentiation of the thorax, and the lack of segmentation of the ovipositor,clearly remove Dasyleptus and Lepidodasypus from immediate relationshipwith the machiloid thysanurans. It should be noted, however, that the ma-chiloids are the nearest known relatives of the Dasyleptidae. If both machi-loids (Microcoryphia or Archaeognatha) and lepismoids (Zygentoma) areincluded as suborders of the order Thysanura, then dasyleptids (Monura)should form a third suborder of Thysanura. In most of their characters theMonura are about as close to the hypothetical “protosymphyla” or ancestorof insects and myriapods, as we are likely to find. Indeed, the agreementwith predicted morphology is remarkable.Other Monura should be searched for in Pennsylvanian-aged rocks. Apoorly preserved body from the Duquesne Shale of Allegheny County,Pennsylvania in the Conemaugh Group, will be described in a forthcomingpaper on the insects of this bed. Several insects described by Matthew (1889,1894, 1910) should be re-examined as possible Thysanura, particularlyArchaescolex corneus Matthew, 1889. New collections should be made inthe Little River Group at Matthew’s locality, the Fern Ledges at St. John,New Brunswick for possible apterygote insects of Riversdalean age (West-phalian A Epoch) about 314 Ma.9REFERENCESBROGNIART, C.1885 [Dasyleptus lucasij. Bull. Soc. ent. France, 1885: 101-102DELANEY, M. J.1959 The life histories and ecology of two species of Petrobius Leach,P. brevistylis & P. maritimus. Trans. Roy. Soc. Edinburgh 63:501-533.DUNBAR, C. O1924 Kansas Permian Insects, Part 1. The Geologic Occurrence and En-vironment of the Insects. Amer. J. Sci. (5) 7:171-203.HANDLIRSCH, A.1908 Die fossilen insketen und die phylogenie der Rezenten formen. Wil-helm Engelmann, Leipzig : 1430pp.MATTHEW, G. F.1889 On Some Remarkable Organisms of the Silurian and Devonian Rocksin Southern New Brunswick. Trans. Roy. Soc. Canada 1V:49-62.MATTHEW, G. F.1894 On the Organic Remains of the Little River Group. No. 2. Trans. Roy.Soc. Canada IV: 89-100.MATTHEW, G. F.1910 Remarkable Forms of the Little River Group. Trans. Roy. Soc. CanadaIV: 115-131.MOORE, R. C.1936 Pennsylvanian and lower “Permian” rocks of the Kansas-Missouri re-gion. Kansas Geol. Soc. Guidebook, 10th Ann. Field Conf. 12 pp.SHAROV, A. G.1957 Svoyeobraznye palezoiskiye beskrylye nasekomye novogo otryadaMonura (Insecta, Apterygota). Peculiar Palaeozoic wingless insectsof the new order Monura (Insecta, Apterygota). Dokl. Akad. NaukS. S. S. R. 115:796-798.SHAROV, A. G1966 Basic Arthropodan Stock with special Reference to Insects. PergamonPress, Oxford: 271 pp.TIEGS, O. W., & S. M. Manton1958 The evolution of the Arthropods. Biol. Rev. 33:255-337.TUXEN, S. L1960 Ontogenie und Phylogenie bezogen auf die apterygoten Insekten.Zool. Anz. 164:359-363.

A Dasyleptid from the Permian of Kansas, Lepidodasypus Sharovi N. Gen., N. SP. (Insecta: Thysanura: Monura)

https://repositories.lib.utexas.edu/bitstream/2152/29897/1/tmm-pss-30.pdf

A Dasyleptid from the Permian of Kansas, Lepidodasypus Sharovi N. Gen., N. SP. (Insecta: Thysanura: Monura)

Abstract

Similar works

Full text

Available Versions

Texas ScholarWorks