DEVONIAN AULACOPLEURID TRILOBITESOF THE MALVINOKAFFRIC REALM

JONATHAN M. ADRAIN & GREGORY D. EDGECOMBE

ADRAIN J.M. & EDGECOMBE G.D. 1996. Devonian Aulacopleurid trilobites of the Malvinokaffric realm. [Les trilobitesAulacopleuridés dévoniens du domaine Malvino cafre]. GEOBIOS, 29, 4: 417-436. Villeurbanne le 31.08.1996.

Manuscrit déposé le 10.08.1994; accepté définitivement le 10.05.1995.

ABSTRACT - Aulacopleurid trilobites of the Malvinokaffric Realm (Lower and Middle Devonian) of South America andSouth Africa include seven species (of which six are formally named) assigned to two genera. These include a distinctsubclade of the otarionine Maurotarion ALBERTI, 1969, and at least two species of Malimanaspis BALDIS & LONGO-BUCCO, 1977, a genus of problematic affinities. Malimanaspis is considered a subjective senior synonym of GoodsiraspisADRAIN & CHATTERTON,1993. Malvinokaffric aulacopleurid diversity includes two separate invasions of cosmopolitantaxa with long independant histories and obvious close comparisons among species from the lower latitudes. NewBolivian species include Maurotarion isaacsoni (Lower Devonian, Gamoneda Formation), M. racheboeufi (Emsian, lelaFormation), and M. legrandi (Eifelian, Belén Formation). One additional new species ofMaurotarion is reported in opennomenclature. The specific concept of Maurotarion dereimsi (KOZLOWSKI,1923), to which almost all South Americanaulacopleurids have at times been referred, is restricted to late Lochkovian or earliest Pragian material, very likely fromthe lower member of the lcla Formation, Chuquisaca Department, Bolivia. Malimanaspis angustilimbata PEK &VANEK, 1991, is revised on the basis of new material.

KEYWORDS: TRILOBITA, AULACOPLEURIDAE, DEVONIAN, SOUTH AMERICA.

RÉSUMÉ - L'étude des trilobites aulacopleuridés du domaine Malvinocafre (Dévonien inférieur et moyen) d'Amériquedu Sud a permis de distinguer sept espèces, dont six nouvelles. Les espèces appartiennent à deux genres. Cinq espècessont attribuées au genre Maurotarion ALBERTI, 1969 ; les deux autres sont rapportées au genre Malimanaspis BALDIS& LONGOBUCCO, 1977, dont la position taxonomique demeure incertaine. Le genre Malimanaspis est ici considérécomme un synonyme senior subjectif de Goodsiraspis ADRAIN & CHATTERTON,1993. L'étude des aulacopleuridés mal-vinocafres a permis de distinguer deux invasions séparées de taxons cosmopolites qui sont restées indépendantes sur delongues périodes. Ces espèces se comparent bien avec celles provenant des basses latitudes. Trois nouvelles espèces,Maurotarion isaacsoni, M. racheboeufi, et M. legrandi sont définies. Une autre forme, attribuée au genre Maurotarion,est laissée en nomenclature ouverte. La définition de ces nouvelles espèces a permis de modifier l'idée que tous les aula-copleuridés d'Amérique du Sud devaient être rapportés à Maurotarion dereimsi (KOZLOWSKI, 1923). L'espèce M.dereimsi est maintenant restreinte au matériel d'âge lochkovien terminal tardif et praguien basal précoce provenant dumembre inférieur de la Formation Icla, Département de Chuquisaca, en Bolivie. L'espèce Malimanaspis angustilimba-ta PEK & VANEK, 1991, est redéfinie sur la base de ce nouveau matériel. .

MOTS-CLÉS: TRILOBITA, AULACOPLEURIDAE, DÉVOJ\TIEN,AMÉRIQUE DU SUD.

INTRODUCTION members of the endemic (Eldredge & Ormiston1979 ; Eldredge & Branisa 1980) family Calmonii-dae Delo, 1935, together with moderately diverseendemic dalmanitids. Other groups are oflow diver-sity and generally rare. The taxonomic make up ofthe faunas has been reviewed by Eldredge &Ormiston (1979).

Aulacopleurids are rare but widespread elements ofthe Malvinokaffric Realm, and three species havethus far been established. Despite a lengthy history

The unique character of the late Silurian andDevonian trilobite faunas of much of SouthAmerica, the Falkland Islands, and South Africa,led Richter & Richter (1942) to propose the termMalvinokaffric Province for the palaeobiogeogra-phic region. Eldredge and Ormiston (1979) conclu-ded that endemism ofthe trilobites was sufficient todesignate a Realm (Kauffman 1973).Trilobite fau-nas of the Malvinokaffric Realm are dominated by

FIGURE1 -Map showing position ofcollecting localities in Bolivia (afterRacheboeuf 1992). Stippling =Altiplano ; slashes SierrasSubandinas. Situation géogra-phique des localités échantillonnéesen Bolivie : pointillé = Altiplano ;hachures = Sierras Subandinas.

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of study, however, Malvinokaffric aulacopleuridsremain very poorly known. The available illustra-tions are scarcely adequate, most figured specimenshave been internal moulds, and neither the mor-phology nor phylogenetic relationships of the trilo-bites are well understood. Material has typicallybeen referred, somewhat indiscriminately, to"0tarion dereimsi (KOZLOWSKI, 1923)".The purposeof this work is the clarification of specific concepts,through revision and redescription of allMalvinokaffric aulacopleurids to which we havehad access, together with consideration of theirimplications for paleobiogeography.We conclude that the Malvinokaffric aulacopleuridsrepresent two minor radiations whose ancestry isfound in cosmopolitan groups that have much lon-ger (Ordovician and Silurian) histories in the lowlatitudes. The introduction of these stocks into theMalvinokaffric Realm occurred by the earliestPragian and Emsian, respectively, and two separa-te events of aulacopleurid migration to the south in

the Lower Devonian seem most probable. Eldredge& Ormiston (1979)proposed that the Malvino-kaf-fric aulacopleurids were derived from cosmopolitantaxa already present in South America in theSilurian. Our revised taxonomy, recognizing theMalvinokaffric aulacopleurids as Maurotarion andMalimanaspis, alters this model in that theseclades are not known from pre-Devonian strata ofSouth America.

New material treated in this work is derived fromthe Lower and Middle Devonian ofBolivia (see Figs.1, 2). Lithostratigraphic units are as described indetail by Isaacson (1977) and Isaacson & Sablock(1988),who interpreted the predominantly marineclastic sequence as having been deposited in anintracratonic basin with a mainly western sedimentsource (see also Isaacson & Sablock 1990).Withinthe Central Andean intracratonic basin, aulaco-pleurid trilobites are known in Bolivia from theAltiplano and the Sierras Subandinas (see Fig. 1 forcollection localities). On the northern Altiplano, La

FIGURE 2 - Comparison of strati-graphic sequences and speciesranges for taxa dealt with herein.Solid lines are confirmed ranges ;dashed lines are maximum possibleranges, following from impreciselylocalized occurrences. Correlationsand age assignments of theAltiplano and Chuquisaca sequen-ces followRacheboeuf et a!. (1993),modified by Blieck et al. (in press).Tarija sequence modified fromIsaacson (1977). Comparaison dessuccessions stratigraphiques et de ladistribution verticale des espècesconsidérées. Les traits pleins corres-pondent aux extensions vérifiées, lestirets aux extensions maximales pos-sibles d'après les récoltes mal loca-lisées. Corrélations et âges attribuésd'après Racheboeuf et aL (1993),modifiés par Blieck et aL (sous pres-se). Séquence de Tarija d'aprèsIsaacson (1977) modifiée.

AGES ALTIPLANO

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LU FormationUJ ILiii Upper Member0-

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I-BELEN

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Paz Department, aulacopleurids occur in the lowerand upper members of the Belén Formation.Lithologies are principally siltstone and mudstonerepresenting shallow subtidal environments(Isaacson 1977).Aulacopleurids are known from theupper member at Chacoma, Belén, and Pujravi(Maurotarion legrandi and Malimanaspis angusti-limbata PEK& VANEK,1991),while a single speci-men is known from the lower member at Chiaru-mani, La Paz Department (Malimanaspis sp.).

The correlation ofthe Altiplano sequence with unitsin the Sierras Subandinas has recently beenappraised by Racheboeuf (1992), with modificationby Blieck et al. (in press). Aulacopleurid occurrencesin the Sierras Subandinas are in the Icla Formationin Chuquisaca Department and the GamonedaFormation in Tarija Department. Distinct species of

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CHUQUISACA

SAIPURU Fm.

•IQURIFormalion

--- 1---

LOS MONOS Fm.

1--- 1---

HUAMAMPAMPAFormation

IClAFormation

Upper Member

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FormationLower Member

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Maurotarion are identified from the basal beds ofthe lela Formation (those bearing a distinctive"8caphiocoelia fauna") and in the lower beds of theupper member of the formation. Specimens fromthe first level, with the 8caphiocoelia fauna, havebeen collected at El Peral, east of Presto, and atAgua Castilla, near Zudafiez [Maurotarion dereim-si (KOZLOWSKI, 1923)].A second species occurs inthe lower part of the Gamoneda Formation at ElCondor, Tarija (Maurotarion isaacsoni nov. sp.).Aulacopleurids in the upper Icla are known fromlela and Padilla (Maurotarion racheboeufi nov. sp.).Isaacson (1977) considered the 8caphiocoelia bea-ring portion ofthe Icla Formation to be ofvery shal-low water origin, possibly intertidal, with subtidaldeposition of shales and mudstones in the uppermember. Aulacopleurids in the upper member arepreserved as moulds in argillaceous nodules, dis-

play a high degree of sclerite articulation, and inclu-de both outstretched and enrolled specimens.The chronostratigraphy of Devonian units on theAltiplano and in the Sierras Subandinas has beenrevised by Racheboeuf et al. (1993), and that workmodified by Blieck et al. (in press) (see Fig. 2). Thisrecognizes that aulacopleurid occurrences in theBelén Formation are of probable Emsian andEifelian ages (in the lower and upper members, res-pectively). Trilobites treated here from the IclaFormation are dated by Racheboeuf et al. (1993) aslate Lochkovian or earliest Pragian (the Scaphio-coelia fauna) and late? Emsian (in the lower beds ofthe upper member).

SYSTEMATIC PALEONTOLOGYRepository - Illustrated specimens are housed in the palaeon-tological collections of the American Museum ofNatural History,New York (prefix AMNH), the Australian Museum, Sydney(AMF), the Museo de Historia Natural de Cochabamba (MHNC),the Muséum National d'Histoire Naturelle, Paris (MNHN), theSedgwick Museum, Cambridge (SMC), and the United StatesNational Museum ofNatural History (Smithsonian Institution),Washington (USNM).

Superfamily AULACOPLEUROIDEAAngelin, 1854Family AULACOPLEURIDAEAngelin, 1854

Subfamily OTARIONINAERichter & Richter, 1926Genus Maurotarion ALBERTI,1969

Type species - Harpidella maura ALBERTI, 1967, Ludlow,Morocco.

Discussion -This genus has been rediagnosed andfully discussed by Adrain & Chatterton (1995b).Holloway & Sandford (1993) have also recognizedthe validity ofMaurotarion, and have independent-

420

ly diagnosed the genus. WhiIe the generic conceptsof these workers are essentially in agreement, thediagnosis presented by Holloway & Sandford (1993,p. 90) consists in large part of characters that aremore generally distributed, and hence irrelevant toany characterization ofMaurotarion as a monophy-letic group. Adrain & Chatterton (1995b) diagnosedthe genus on the basis of the following unique syna-pomorphies : anterior border longer medially thanlaterally; anterior border furrow of distinct inver-ted "V" shape ; palpebral lobes extended laterallypast maximum divergence of anterior sections offacial sutures; eye with much reduced socle; libri-genal field narrow relative to length; and librigenallateral border furrow very shallow, with lateral bor-der inflated and broader than posterior border.The name Branisella PRIBYL& VANEK,1981, pro-posed as a monotypie subgenus of Harpidella withCyphaspis dereimsi KOZLOWSKI,1923, as type, is ajunior homonym of Branisella HOFFSTETTER,1969,an Oligocene primate. No replacement name is pro-posed, as the type species is considered to belong toMaurotarion ALBERTI, 1969, as interpreted byAdrain & Chatterton (1995b). Five species ofMaurotarion are recognized from the Malvinokaf-fric Realm herein. The species share a single promi-nent apomorphy, the extreme posterior expansion ofthe posterior and laterallibrigenal borders, and thebase of the genal spine. In other respects, however,the species are typical members ofMaurotarion.Three ofthe Malvinokaffric species (M. dereimsi, M.racheboeufi, and M. legrandi) are obviously closelyrelated. They are referred to as the "dereimsi group"in the following discussion. Members of the dereim-si group most closely resemble M. periergum (HAAs,1969), from the Pragian of the Cortez Range, cen-

PLATE 52

Figs. 1-3,5-9 -Maurotarion dereimsi (KOZLOWSKI,1923).1. Lectotype,dorsal exoskeleton,latex cast of external mould,MNHN R.5084l, Tarabuco, presumably lcla Formation, Chuquisaca Department, Bolivia, dorsal view, x 3. 2,3,5,7.Cranidium and left librigena, latex cast ofexternal mould,MHNC8113,lcla Formation, lowermember (ScaphiocoeliaZone,late Lochkovian or earliest Pragian), Presto El Peral, Chuquisaca Department Bolivia (colI.P.Racheboeuf),leftlateral, oblique,anterior, and dorsal views,x 3. 6,8,9.Cephalon and thoracic segments, internal mould,AMNH44995,lcla Formation, lowermember (Scaphiocoelia Zone,late Lochkovianor earliest Pragian), Agua Castilla, near Zudafiez,Chuquisaca Department, Bolivia (coll.L. Branisa), left lateral, dorsal, and oblique views, x 3.1. Lectotype, carapacedorsale, moulage en latex du moule externe, Tarabuco, probablement Formation d'Ida, Département de Chuquisaca,Bolivie, vue dorsale. 2,3,5,7. Cranidium et librigène gauche, moulage en latex du moule externe, Formation d'Ida,membre inférieur (Zone à Scaphiocoelia,Lochkovien supérieur ou Praguien basal), Presto El Peral, Département deChuquisaca, Bolivie (coll. P. Racheboeuf), vues latérale gauche, oblique, antérieure et dorsale. 6,8,9. Céphalon et partiedu thorax, moule interne, Formation d'Ida, membre inférieur (Zone à Scaphiocoelia,Lochkovien supérieur ou Praguienbasal), Agua Castilla, près de Zudafiez, Département de Chuquisaca, Bolivie (coll.L.Branisa), vues latérale, dorsale etoblique.

Fig. 4 - Maurotarion isaacsoni nov. sp. 4. Cranidium and right librigena, latex cast of external mould, AMNH 44996,lower part ofGamoneda Formation (Early Devonian),El Côndor,Tarija Department, Bolivia (colI.L. Branisa), dorsalview, x 7.5. Cranidium et librigène droit, moulage en latex du moule externe, partie inférieure de la FormationGomoneda (Dévonien inférieur), El Condor, Département de Tarija, Bolivie (coll. L.Branisa), vue dorsale.

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Pl. 52J.M. Adrain & G.D. Edgecombe

tral Nevada, U.S.A. (this species is currently underrevision by J.M. Adrain & B.D.E. Chatterton). Inparticular, M. periergum shows a similar inflation ofthe genal spine and genal spine base (Haas 1969,pI.81, figs. 7, 8), although not so prominently develo-ped as in the M. dereimsi group. Significantly, thelateral border furrow shallows and disappears infront of the genal angle in M. periergum, while theposterior border furrow bends backward distally torun along the dorsal aspect of the genal spine. Thisis a situation identical to that in members of thedereimsi group (cf.Haas 1969, pI. 81, fig. 7 with PI.1, fig. 3). Furthermore, while the species have a longanterior border that is longer sagittally than exsa-gittally (a general character of the genus), the leng-th differences are more subtle in both the dereimsigroup and in M. periergum than in most congene-ries. The species differ in the following ways : M.periergum has a much more prominent cranidialtuberculate sculpture, with scattered tubercles onthe preglabellar field and frontal area, prominenttubercles toward the rear of the glabella and on L1,as well as a prominent median occipital node andtransverse row ofoccipital tubercles, while cranidialtuberculate sculpture is all but absent in membersof the dereimsi group, save for a very fine and sub-dued median node and transverse occipital row; theglabella of M. periergum is longer relative to its .width ; and both the anterior and lateral cephalicborder furrows are deeper (although still shallow)in M. periergum. Finally, the thoraces ofM. dereim-si} M. racheboeufi, and M. legrandi have 14 seg-ments, while that of M. periergum has 13. Haas(1969, p. 646) reported 14, with a thoracic axialspine on the seventh segment. This was based onspecimen USNM 161172, which was described, butonly the posterior part of which was illustrated(Haas 1969, pI. 81, fig. 11). New collections fromNevada include several articulated specimens defi-nitely conspecific with the remainder of Haas's(1969) illustrated material ofM. periergum (inclu-ding the holotype), and all have thoraces of 13 seg-ments lacking an axial spine. Rare isolated seg-ments with spines have been found, and likelybelong to an uncommon second species, together

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with USNM 161172,which also shows profound dif-ferences with newly collected pygidia. Despite thesedistinctions, it is reasonable to assume that M. per-iergum is the sister species of the small Malvino-kaffric radiation.

The relationships of the remaining Malvinokaffricspecies,M. isaacsoni nov. sp. and the South AfricanMaurotarion nov. sp. A, are more problematic. Theyresemble each other in two derived features. First,both have a librigena with the lateral border furrowalmost completely effaced, and the lateral borderextremely broad. The genal spines have exceedinglybroad bases, but taper to relatively short lengths,giving a distinct sub-triangular appearance inexternal view. In Maurotarion nov. sp. A, the genalspine reaches only the middle of the fifth thoracicsegment in the nearly fully outstretched specimen(the spine is slightly longer in M. isaacsoni, butwhile it reaches the seventh segment in the holoty-pe, this is exaggerated due to dorsoventral flexureof the thorax). In contrast, the lectotype of M.dereimsi has genal spines which, while incomplete,have already reached the eighth segment. Second,both species have a thorax in which the section ofthe pleural lobe adaxial to the fulcrum is very nar-row.This feature is not unique within the genus, butdoes serve to differentiate them from the dereimsigroup and M. periergum, which have much broaderadaxial pleural lobes. Taken together, these twocharacters are interpreted as synapomorphic andthe species, despite their considerable differences(see comparison under M. isaacsoni, below), areconsidered sister taxa.At issue is the relationship ofM. isaacsoni and M.nov.sp. A to the dereimsi group. If they are not partof that clade, this would imply separate events ofEarly Devonian (minimally Pragian?) migration,for a total of three aulacopleurid invasions in theDevonian. The balance of evidence, however, indi-cates that a relationship probably exists. Despitedifferences, the expanded genal spine bases areseen elsewhere only in M. periergum and thedereimsi group. Hence, we tentatively interpret theentire Malvinokaffric Maurotarion radiation as a

PLATE 53

Figs. 1-4, 6 - Maurotarion isaacsoni nov. sp. 1-4,6. Holotype, dorsal exoskeleton, latex cast of external mould, USNM483761, lower part of Gamoneda Formation (Early Devonian), El Condor, Tarija Department, Bolivia (original ofBranisa 1965, p. 96, pl. 16, fig. 30), dorsal thorax, dorsal cephalon, oblique, right lateral, and anterior views, x 4.Holotype, carapace dorsale, moulage en latex du moule externe, partie inférieure de la Formation Gamoneda (Devonieninférieur), El Condor, Département de Tarija, Bolivie, vues dorsale du thorax, dorsale du céphalon, oblique, latérale etantérieure.

Figs. 5,7 - Maurotarion nov. sp. A. 5,7. Dorsal exoskeleton, latex cast of external mould, SMC A3062b (internal mould,SMC A3062a, figured by Cooper 1982, p. 14, fig. 8), Bokkeveld Group, South Africa, dorsal and right lateral views, x3. Carapace dorsale, moulage en latex du moule externe SMC A3062b, (moule interne SMC A3062a, figuré par Cooper1982, p. 14, fig. 8). Groupe de Bokkeveld, Afrique du Sud, vues dorsale et latérale.

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Pl53J.M. Adrain & G.D. Edgecombe

monophyletic group, including also the NorthAmerican M. periergum.

This hypothesis of relationship suggests that theMalvinokaffric Maurotarion species group was anEarly Devonian migrant into the subpolar region.Eldredge & Ormiston's (1979) proposal that SouthAmerican Silurian aulacopleurids gave rise to theMalvinokaffric endemics requires as yet undiscove-red South American Silurian Maurotarion speciesto nest elosest to the Devonian species group (andalso that M. periergum be an emigrant from thesouth). Maurotarion is unknown from the SouthAmerican Silurian, but is common in the Silurian ofthe central and eastern United States. The phyloge-ny endorsed here and its prediction of migrationinvokes fewer ad hoc assumptions.

Maurotarion dereimsi (KOZLOWSKI,1923)PI. 52, figs. 1-3, 5-9

1923 Cyphaspis dereimsi KOZLOWSKI, p. 61, pI. 4, fig.15 (nonfigs. 16, 17, =Maurotarion racheboeufi nov. sp.).

1965 Otarion dereimsi (KOZLOWSKI) : Branisa, p. 96, p1.16, fig.29 (non pI. 16, fig. 30 = Maurotarion isaacsoni nov. sp.).

1977 Malimanaspis dereimsi (KOZLOWSKI) : Baldis & Longo-bucco, p. 154.

Material and Occurrence - Lectotype (designa-ted by Wolfart 1968, p. 56) : dorsal exoskeleton,MNHN R.50841 (Kozlowski 1923, pI. 4, fig. 15 ; PI.1, fig. 1 herein), from Tarabuco, ChuquisacaDepartment, presumably from the- Icla Formation.Pek & Vanek's (1991) citation of the upper BelénFormation as the type stratum followed Wolfart(1968), but has no basis, since that unit is not pre-sent in the type area at Tarabuco. Assigned speci-mens: MHNC 8113, Icla Formation, lower member(Scaphiocoelia Zone, late Lochkovian or earliestPragian), Presto El Peral, Chuquisaca Department;

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AMNH 44995, Icla Formation, lower member(Scaphiocoelia Zone), Agua Castilla, near Zudaiiez,Chuquisaca Department.Diagnosis - Glabella subquadrate ; S2 stro:q.glyimpressed, glabella with distinct lateral constric-tion in front of S2 ; S3 strongly expressed for genus;dorsal cephalon smooth, lacking any tuberculatesculpture; genal spine long, broadened at base, buttapering and tubular distally.

Discussion - The specific epithet dereimsi hasbeen applied at one time or another to six distinctaulacopleurid species treated herein. Much of theconfusion can be attributed to the general rarity ofaulacopleurid specimens coupled with a lack ofmany good illustrations. Contributing to the pro-blem, however, is the fact that the lectotype speci-men is both poorly preserved and poorly localized.We have identified three distinct species' ofMaurotarion, based upon well-localized material,with which the dereimsi lectotype could conceiva-bly be interpreted as conspecific (and for which ithas previously been the only available name).These are : specimens from the late Lochkovian orearliest Pragian Scaphiocoelia fauna of the lelaFormation, Chuquisaca Department ; specimensfrom the lower part of the Gamoneda Formation,Tarija; and specimens from the late? Emsian oftheIcla Formation, Chuquisaca. If taxonomic progressis to be made, dereimsi must either be restricted toits type specimen, or else be shown to represent oneof the three species. While ambiguity exists, thebalance of evidence indicates that the lectotypespecimen is conspecific with the first-cited group ofspecimens, from the basal beds of the IclaFormation at relatively nearby localities inChuquisaca Department.

PLATE 54

Figs. 1-12 -Maurotarion racheboeufi nov.sp., lcla Formation, late? Emsian, Padilla, Chuquisaca Department (exceptFig.7, Gamoneda Formation, Gamoneda, Tarija Department), Bolivia.1,2,4, 5. Holotype,dorsal exoskeleton, latex cast ofexternal mould (posterior of exoskeleton poorly preserved on counterpart internal mould), USNM 483762 (coll;L.Branisa), dorsal left lateral, oblique, and anterior views, x 3. 3,6. Cranidium, internal mould, MNHN R.50843 {syn-type ofMaurotarion dereimsi (KOZLOWSKI,1923)), dorsal and right lateral views, x 2.5. 7. Cephalon and partial tho-rax, latex cast of internal mould, AMNH44997 (coIl.L. Smith), ventral view,x 2.5. 8,9. Cephalon and thoracic seg-ments, internai mould, MNHN R.50482 (syntype ofMaurotarion dereimsi (KOZLOWSKI,1923)), dorsal and left late-ral views, x 2.5.10. Cranidium and right librigena, latex cast of internal mould,USNM 483763 (coIl.L.Branisa), ven-tral view,x 3. 11,12. Dorsal exoskeleton, internal mould and latex cast AMF 93546 (colI.G. Edgecombe),left lateraland ventral views, x 2.5. Formation d'Ida, Emsien supérieur ?, Padilla, Département de Chuquisaca (à l'exception dela Fig. 7, Formation de Gamoneda, Gamoneda, Département de Tarija), Bolivie. 1,2,4,5. Holotype, carapace dorsale,moulage en latex du moule externe (partie postérieure de la carapace conserve mal sur la contre-partie, moule interne),(coll.L. Branisa), vues dorsale, latérale, oblique et antérieure. 3,6. Cranidium moule interne (syntype de Maurotariondereimsi (KOZLOWSKI,1923)) ; vues dorsale et latérale. 7.Céphalon et partiel thorax, moulage en latex du moule inter-nal (coll. L. Smith), vue ventrale. 8,9. Céphalon et segments thoraciques, moule interne (syntype de Maurotariondereimsi (KOZLOWSKI,1923)), vues dorsale et latérale. 10. Cranidium et librigène, moulage en latex du moule interne(coll. L. Branisa), vue ventrale. 11,12. Carapace dorsale, moulage en latex (coll. G. Edgecombe), vues latérale et ven-trale.

Geobiosn° 29, fase. 4

Pl. 54J.M. Adrain & G.D. Edgecombe

On morphological grounds, the lectotype and basalIcla specimens agree most importantly in the pre-sence of a distinctively well-impressed S2 (cf.PI. 52,figs. 1,7,8). They are also alike in the relative effa-cement of the posterior border furrow as it bendsposteriorly to run along the genal spine. This featu-re is shared with the Tarija material (PI. 53, fig. 3),but not with the Emsian material from the IclaFormation, in which the posterior border furrow isquite well-impressed as it runs onto the genal spine(e.g.,PI. 54, fig. 4). The dereimsi lectotype is furthersimilar to the lower Icla specimens but distinct fromthe Tarija specimens in the presence of a relativelynarrow (for the group) genal angle and seeminglylong genal spine (although the latter is somewhatuncertain, since the genal spines of the lectotypeare not completely preserved).Hence, the most profitable and best supported cour-se of action is to fix the specific concept ofMaurotarion dereimsi as a late Lochkovian or ear-liest Pragian taxon, associated with the Scaphio-coelia Fauna of the lowermost Icla Formation inChuquisaca. Accordingly, we have proposed M.isaacsoni nov.sp. for the Lower Devonian specimensfrom the Gamoneda Formation, Tarija Department,and M. racheboeufi nov. sp. for Emsian specimensfrom the lela Formation.Maurotarion dereimsi differs from M. periergum(HAAs, 1969) in the possession of a less tuberculatecranidium ; much shorter anterior border ; morestrongly impressed S2 ; and relatively longer, nar-rower genal spines lacking a dorsal spine row.Maurotarion dereimsi differs from the possiblycontemporaneous M. isaacsoni in the possession ofa shorter anterior border; narrower librigenallate-rai border; narrower, longer genal spines; and occi-pital and thoracic axial rings that lack spines ortuberculation, versus short median spines. Mauro-tarion dereimsi is distinct from the younger M.racheboeufi in the possession of a less distinctly "V"shaped anterior border furrow, more impressed S2,lèss inflated glabella, and unsculptured occipital

426

ring (versus a transverse row of small tubercles).Finally,M. dereimsi differs from the Eifelian Mau-rotarion legrandi in the possession of more impres-sed S2, narrower genal spine, and most particular-ly a wider librigenal field.

Maurotarion isaacsoni nov. sp.PI. 52, fig. 4 ; PI. 53, figs. 1-4, 6

1965 Otarion dereimsi (KOZLOWSKI) : Branisa, p. 96, pI. 16,fig. 3D.

Etymology -After Peter E. Issacson.

Material and Occurrence - Holotype, dorsal exoskeleton,USNM 483761 (PI. 53, figs. 1-4, 6), Gamoneda Formation, lowerpart (Early Devonian), El Condor, Tarija Department, Bolivia;paratype, small cranidium and right librigena, AMNH 44996,same locality and age.

Diagnosis - Anterior border long (sag. ; exsag.) ;genal spine broad at base, tapering rapidly andrelatively short, subtriangular in external view ;occipital ring and thoracic axial rings with singleprominent, but short, median spine.Discussion - The similarity of this species toMaurotarion nov. sp. A, and their affinities, weredealt with above under discussion of the genus.Maurotarion isaacsoni differs from M. nov. sp. A inthe possession of a much longer anterior cranidialborder (and correspondingly wide anterior part ofthe lateral border), longer genal spine, and in parti-cular the presence of short median spines on theoccipital and thoracic axial rings.

Maurotarion nov. sp. API. 53, figs. 5, 7

1925 Cyphaspis Dereimsi KOZLOWSKI: Reed, p. 122, pI. 10,fig. 10.

1982 Malimanaspis? dereimsi (KOZLOWSKI): Cooper, p.14,fig.8.

Material and Occurrence - Single illustrated specimen, dorsalexoskeleton, internal and external moulds, SMC A3062a,b,Bokkeveld Group, precise stratigraphic occurrence unknown (noolder than late Emsian), road cutting between De Doorns andTunnel, Cape Province, South Africa.

PLATE 55

Figs. l-4,6,7,9-11-Maurotarion racheboeufi nov. sp., lower part of upper member oflcla Formation, late? Emsian, lcla,Chuquisaca Department, Bolivia (colI. L. Branisa). 1-4 ..Dorsal exoskeleton, internal mould,AMNH 44998, dorsal, ven-tral, anterior, and right lateral views, x 3.6,7,9,11. Dorsal exoskeleton, internal mould, AMNH 44999, dorsal cepha-lon, dorsal thorax, right lateral, and dorsal pygidium views, x 2.5. 10. Dorsal exoskeleton, latex cast of posterior ofinternal mould, AMNH 45000, ventral view, x 4. Partie inférieure du membre supérieur de la Formation d'Icla, Emsiensupérieur? 1-4. Carapace dorsale, moule interne, vues dorsale, ventrale, antérieure et latérale. 6,7,9,11. Carapace dor-sale, moule interne, vues dorsale céphalon, dorsale du thorax, latérale et dorsale du pygidium. 10. Carapace dorsale,moulage en latex de la partie postérieure du moule interne, vue ventrale.

Figs. 5,8 - Maurotarion legrandi nov. sp. Belén Formation, upper member (Eifelian), Chacoma, La Paz Department,Bolivia. 5,8. Dorsal exoskeleton, latex cast of external mould, AMNH 45001, left lateral and dorsal views, x 3.Formation de Belén, membre supérieur (Eifelien). 5,B. Carapace dorsale, moulage en latex dlf moule externe, vues laté-rale et dorsale.

Geobiosn° 29, fase. 4

Pl. 55J.M. Adrain & G.D. Edgecombe

Discussion - See comments under discussion ofgenus and ofMaurotarion isaacsoni. The single spe-cimen assigned to the taxon has previously beenknown only from illustrations of the internal mould(drawing in Reed 1925, pI. 10, fig. 10 ; photograph inCooper 1982, fig. 8). A latex cast from the counter-part external mould figured herein shows the intactright librigena.

Maurotarion racheboeufi nov. sp.PI. 54, figs. 1-12 ; PI. 55, figs. 1-4,6,7,9-11

1923 Cyphaspis dereimsi KOZLOWSKI,p. 61,pI. 4, figs. 3 =16,17.

Etymology -After Patrick R. Racheboeu£Material and Occurrence - Holotype, dorsal exoskeleton(counterpart moulds), USNM 483762 (pI. 3, figs. 1, 2, 4, 5), lelaFormation (late? Emsian), Padilla, Chuquisaca Department ;paratypes USNM 483763 and AMF 93546, assigned specimensMNHN R.50842 and R.50843, same locality and age.Assignedspecimens AMNH44998-45000,lela Formation, upper member(late? Emsian), lela, Chuquisaca Department, and AMNH 44997,Gamoneda Formation, Tarija Department. Unfigured cranidiumAMF 92953, lela Formation, Rumicorral, CochabambaDepartment.

Collectionsmade by G.D.E.and LeGrand Smith at Padilla andat the type section of the lela Formation at lela have served toelarifYthe position ofMaurotarion racheboeufiwithin the for-mation. The species is of scarce occurrence in the semiresistantconcretion bearing shales just above the Niagara Sandstone atlela, in the lowerpart ofthe upper member ofthe lela Formation.Co-occurring calmoniids in this interval are Kozlowskiaspissuperna (BRANISA& VANEK,1973),Metacryphaeus convexus(ULRICH,1892),M.giganteus (ULRICH,1892),and Pennaia ver-neuili (D'ORBIGNY,1847).AtPadilla,Maurotarion racheboeufiislikewise relatively uncommon, having been collected from anapproximately 20 m interval in which Pennaia verneuili is themost abundant trilobite, with commonMetacryphaeus rotunda-tus (KOZLOWSKI,1923 ; sensu Lieberman 1993),and less abun-dant Kozlowskiaspis superna and Burmeisteria sp.Pennaia ver-neuili ranges higher in the Padilla section to co-occurwithMalvinella haugi (KOZLOWSKI,1923),Schizostylus brevicauda-

428

tus (KOZLOWSKI,1923),and Metacryphaeus curvigena (LIEBER-MAN,1993)and, slightly higher, with all ofthese species as wellas Probolops glabellirostris (KOZLOWSKI,1923) and Bouleiasphaericeps (KOZLOWSKI,1923). The restricted ranges ofKozlowskiaspis superna and Maurotarion racheboeufi,however,correlate the Maurotarion levels at Padilla with the lower bedsofthe upper member at lela.

A specimen ofMaurotarion racheboeufi from Gamoneda, TarijaDepartment (pI. 54, fig. 7), was collected by LeGrand Smith inbeds informally assigned to the giganteus Zone.This biostrati-graphic unit was based on the successionin the Belén Formationof the Altiplano (Wolfart 1968).A correlation with the centralSubandean Zone can be inferred from the occurrence ofMetacryphaeusgiganteus in the lowerpart of the upper memberof the lela Formation. As such, the occurrence ofMaurotarionracheboeufiin the Gamoneda Formation at Gamoneda is proba-bly equivalent to that at lela and Padilla.

Diagnosis - Dorsal cephalic sculpture subdued ;anterior and lateral cephalic borders very shallow;glabella moderately inflated and vaulted ; genalspine inflated and broad at base; thorax of 14 seg-ments lacking axial spine ; axial lobe of given tho-racic segment wider (tr.) than pleural lobe; trans-verse row of about 10 fine tubercles on each thora-cic axial ring ; pygidium with two prominent axialrings and a poorly defined third.

Description - Cranidium with length (sag.) 75-80percent width (tr.) across palpebral lobes ; width(tr.) across maximum divergence of anterior sec-tions of facial sutures 80-85 percent width acrosspalpebral lobes ; anterior border nearly flat, withonly very gentle dorsal convexity, slightly longersagittally than exsagittally, lacking sculpture; ante-rior border furrow very shallow, deepest sagittally,shallowing abruptly near anterior section of facialsuture; preglabellar field similar in length (sag.) toanterior border, slightly shorter exsagittally, dorsal-ly convex in front of preglabellar furrow, slopingevenly anteriorly, lacking sculpture ; glabella withlength (sag., including occipital ring) 95 percent

PLATE 56

Figs. 1-3,5,9 -·Maurotarion legrandi nov. sp. Belén Formation, upper member (Eifelian), Chacoma and Belén, La PazDepartment, Bolivia (colI. L. :&anisa). 1. Holotype, dorsal exoskeleton, internal mould, AMNH 45002 (Chacoma), dor-sal view, x 4. 2,3. Cranidium and right librigena, latex casts of external and internal moulds,AMNH 45003 (Belén),dorsal and ventral views, x 4. 5,9. Cranidium and right librigena, internal mould. AMNH 45004 (Chacoma), obliqueand dorsal views, x 4. Formation de Belén, membre supérieur (Eifelien). 1. Holotype, carapace dorsale, moule interne,uue dorsale. 2,3. Cranidium et librigène, moulages en latex des moules externe et interne, vues dorsale et ventrale. 5,9.Cranidium et librigène, moule interne, vues oblique et dorsale.

Figs. 4,6-8,12 - Malimanaspis angustilimbata PEK & VANEK, 1991. Belén Formation, upper member (Eifelian),Chacoma, La Paz Department, Bolivia. 4,6-8,12. Dorsal exoskeleton~ internal mould, AMNH 45005, dorsal, dorsalpygidium, anterior, oblique, and right lateral views, x 3. Formation de Belén, membre supérieure (Eifelien). 4,6-8,12.Carapace dorsale, moule interne, vues dorsale, dorsale du pygidium, antérieure, oblique et latérale.

Figs. 10,11,13 - Malimanaspis sp. Belén Formation, upper third of lower member (probably Emsian), Chiarumani, LaPaz Department, Bolivia (coIl. P. Racheboeuf). 10,11,13." Dorsal exoskeleton, latex cast of partially infilled externalmould, MHNC 8114, anterior, dorsal, and right lateral views, x 4. Formation de Belén, tiers supérieur du membre infé-rieur (probablement Emsien). 10,11,13. Carapace dorsale, moulage en latex du moule externe, partiellement rempli,uues antérieure, dorsale et latérale.

Geobiosn° 29, fase. 4

Pl. 56J.M. Adrain & G.D. Edgecombe

maximum width across L1, with even, moderate,dorsal convexity in sagittal profile ; preglabellarfurrow with slight to moderate anterior convexity,deepest and longest in transverse slot-like sagittalarea, shallowing considerably exsagittally ; axialfurrows laterally convex around L1, then withsecond, separate lateral convexity around anteriorpart of median lobe, converging slightly anteriorly,broad and shallow, shallowing anteriorly ; medianglabellar lobe lacking sculpture except for veryfaint, scattered tubercles on posteriormost part; L1large, width 20 percent that of glabella, length(exsag.) more than 40 percent that of glabella (sag.,including occipital ring), lacking sculpture exceptpossibly a few very faint tubercles along S1 ; S1deep anteriorly, shallowing somewhat posteriorly;S2 a very faint notch dorsally, but a prominent fur-row ventrally (pI. 54, fig. 12) ; S3 visible as faint fur-row on internal moulds ; SOdeep behind LI, long(sag., exsag.) behind median glabellar lobe, shallow;LO short (sag., exsag.), about 60 percent length ofanterior border, shortening behind L1, with faintmedian node and very subdued transverse row ofapproximately 10 tubercles near to posterior mar-gin; faint bicomposite eye ridge visible dorsally, run-ning anteromedially ; interocular fixigena of mode-rate width, with considerable dorsal inflation bet-ween axial furrow and distinctly impressed palpe-bral furrow ; palpebral furrow broad, shallow,impressed most strongly just behind eye; palpebrallobe long, wide, describing more than one half circlein plan view, and with faint median pit ; posteriorborder furrow short (exsag.) and deep; posteriorborder with narrow (tr.) part proximal to fulcrum,then broader and longer (exsag.), posteriorly inflec-ted part distal to fulcrum, lacking tuberculatesculpture; very small, barely distinct fossula ven-trally at junction of axial and preglabellar furrows.Librigenal field with width (tr. ; measured at mini-mum point near front of eye) 25 percent length(exsag.), entirely smooth and lacking tuberculate orcaecal sculpture ; eye large, with height 50 percent

430

length (exsag.), and with very faint, narrow (tr.),ring-like socle (Pl. 54, figs. 2, 4, 11) ; lateral borderinflated, broadening posteriorly; lateral border fur-row very shallow, deepest anteriorly, becoming obs-cure posteriorly, lacking sculpture; posterior borderfurrow beginning as shallow incision along strongsutural ridge behind eye, becoming deeper abaxial-ly, forming relatively deep, slot-like depression infront ofgenal angle, then extended as shallower fur-row posteriorly along dorsal aspect of genal spine;posterior border inflated, narrow (tr.) due to courseof posterior section of facial suture, very long(exsag.), lacking sculpture; genal spine with verybroad, transversely inflated base, incorporatingexpansion of posterior part of lateral border andposterior border, long and inflated down length ;doublure narrower anteriorly, broadened posterior-ly to underlie expanded genal spine' base, withsculpture of closely set, moderately fine terracelines running subparallel to lateral margin.Rostral plate (pI. 54, figs. 7,10) subtriangular, broadanteriorly with long connective sutures, with veryminor transverse extent at posterior margin (i.e.connective sutures not quite meeting posteriorly),and with subparallel terrace lines ventrally, run-ning uninterrupted across connective sutures.Hypostome unknown.Thorax of 14 segments; pleural lobewith width (tr.)60 percent that of axial lobe anteriorly, increasing to80 percent by posteriormost few segments ; seg-ments short (sag., exsag.) ; fulcrum positioned at 40percent width (tr.) of pleural lobe anteriorly, closerto axial furrow posteriorly ; axial ring with length(sag.) 10 percent width (tr.), anterior edge transver-sely nearly straight, posterior edge describing veryshallow "W"shape in dorsal view, describing nearlycomplete semicircle in transverse profile, withtransverse row of about 10 subdued, evenly spacedtubercles across entire width ; axial ring separatedfrom articulating half ring by deep furrow withlength (sag., exsag.) about two thirds that of ring;

PLATE 57

Figs. 1-3 - Maurotarion legrandi nov. sp., presumably Belén Formation, Chacoma, La Paz Department, Bolivia. 1-3.Dorsal exoskeleton, internal mould, AMF 93544, dorsal, right lateral, and anterior views, x 3. ProbablementFormation de Belén. 1-3. Carapace dorsale, moule interne, vues dorsale, latérale et antérieure.

Figs. 4,7 - Maurotarion sp., from the Dipleura dekayi Zone (Sica Sica Formation, Givetian), Cruz Loma, La PazDepartment, Bolivia (coll. S. de la Serna). 4,7. Dorsal exoskeleton, internal mould, AMF 93545a, dorsal and left late-ral views, x 3.De la Zone à Dipleura dekayi. 4,7. Carapacedorsale, moule interne, vues dorsale et latérale.

Figs. 5,6,8-12 -Malimanaspis angustilimbata PEK & VANEK,1991. 5,6,8. Cephalon and partial thorax, internal mould,AMF 92954, presumably Belén Formation, Pujravi, La Paz Department (coll.S. de la Serna), dorsal, right lateral, andanterior views, x 3.5.9·12. Dorsal exoskeleton, internal mould, AMF 92955, from glacial rubble near Lahuachaca (pre-sumably Belén Formation), La Paz Department (colI.L. Smith), dorsal cephalon, pygidium, right lateral, and anteriorviews, x 3.5. 5,6,8. Céphalon et partie du thorax, moule interne, probablement Formation de Belén, vues dorsale, laté·rale et antérieure. 9-12. Carapace dorsale, moule interne, d'un bloc glaciaire près de Lahuachaca (probablementFormation de Belén), vues dorsale du cranidium, dorsale du pygidium, latérale et antérieure.

Geobiosn° 29, fase. 4

Pl. 57J.M. Adrain & G.D. Edgecombe

articulating half ring slightly longer than axial ring(sag.), tapering in length abaxially ; axial furrowshallow, broad (tr.) ; pleural furrow shallow adaxial-ly, barely in contact with axial furrow, deepeningimmediately abaxially to run posterolaterally asshort (exsag.), deeply incised straight line past ful-crum, bowed posteriorly to run along posterior partof articulating facet ; posterior pleural band abouttwice as long (exsag.) as anterior band proximal tofulcrum ; sharp, subtriangular articulatory bossdeveloped on leading edge of anterior band at ful-crum, with notch to receive it on posterior band ofsucceeding segment; articulating facet with slight-ly lobate posterior edge ; pleural tips subquadrate,but gently rounded; small apodeme positioned ven-trally at posterior edge of axial furrow on all seg-ments ; doublure developed beneath pleural tip intorelatively broad platform anteriorly, forming poste-riorly directed notch for reception ofleading edge ofimmediately posterior segment during enrollment.Pygidium known only from internal moulds; leng-th (sag., excluding articulating half ring) 50 percentmaximum width (tr.) ; axis with anterior widthabout 40 percent pygidial width ; axial furrowsconverging posteriorly and meeting posteromedial-ly to fully define axis ventrally; first two axial ringsprominent, third faint, posterior rings not develo-ped ; pleural and interpleural furrows of segmentsone to three becoming increasingly less distinct,those of segment four variably present, very faintwhen occurring ; doublure relatively broad, withsculpture of terrace lines of similar size to those ofcephalic doublure, running subparallel with pygi-dial margin.

Discussion - Maurotarion racheboeufi was compa-red with M. dereimsi above. It differs from the youn-gerMaurotarion legrandi in the possession ofa widerlibrigenal field, relatively narrower lateral border,and shallower anterior border furrow.The species areotherwise very similar. Nevertheless, these diffe-rences are pervasive, and are well displayed by all ofthe upper Belén specimens studied herein.

Maurotarion legrandi nov. sp.PI. 55, figs. 5, 8 ; PI. 56, figs. 1-3,5,9 ; PI. 57, figs. 1-3

1981 Harpidella (Branisella) dereimsi (KOZLOWSKI) : Pribyl &Vanek, p. 170-171, PI. 1, figs. 10-12.

1991 Harpidella (Branisella) dereimsi (KOZLOWSKI) : Pek &Vanek, p. 77, PI. 3, figs. 1-3.

432

Etymology - After LeGrand Smith.

Material and Occurrence - Holotype, AMNH 45002 (PI. 5, fig.1), from the upper member of the Belén Formation (Eifelian),Chacoma, La Paz Department; paratypes AMNH 45001, 45004,from the same locality; assigned specimen AMNH 45003, fromthe upper member of the Belén Formation (Eifelian), Belén, LaPaz Department ; assigned specimen AMF 93544, fromChacoma, presumably Belén Formation.

Diagnosis -Anterior border furrow very long (sag.,exsag.) and depressed ; glabella with scatteredtubercles on at least posterior of median lobe andL1 ; librigenal field exceedingly narrow (tr.), espe-cially at midlength of eye ; lateral border and baseof genal spine broad.Discussion -The very narrow librigenal field andlong, depressed anterior border furrow immedia-tely distinguish this species from all congenerics.In addition, two specimens (pI. 55, fig. 8 ; PI. 56,fig. 3) indicate that the posterior part of themedian glabellar lobe bore small, scatteredtubercles, in contrast to the near total lack ofsculpture of other Malvinokaffric species. Seeadditional comments under discussion of genusand other species above.

Maurotarion sp.PI. 57, figs. 4, 7

Mpterial and Occurrence - Assigned specimen AMF 93545,from the Dipleura dekayi Zone, Cruz Loma, La Paz Department,Bolivia. The occurrence of Dipleura dekayi has been assigned tothe Sicasica Formation (Wolfart 1968), a view endorsed by P.Isaacson (pers. comm., 1994). Racheboeuf(1992) and Racheboeufet al. (1993) identified the Dipleura level as the lower part of theupper member of the Belén Formation, but Blieck et al. (1995)have revised this assignment, and have also placed the Dipleuradekayi Zone in the Sicasica Formation. The age is henceGivetian.

Discussion - A single oustretched internal mould(with poor associated counterpart) is possibly theyoungest otarionine known from South America.While certainly Maurotarion, it cannot be shownthat the specimen is a member of the dereimsigroup, as it lacks librigenae. It is clearly distinctfrom the slightly older M. legrandi in its shorter,shallower anterior border furrow and more inflatedglabella. It is further distinguished from both M.legrandi and all other Bolivian congenerics in itsvery narrow pleural lobes and very small pygidium.The specimen likely represents a new species, but

PLANCHE 58

Figs. 1-7 - Malimanaspis angustilimbata PEK & VANEK, 1991. 1-7. Dorsal exoskeleton, internal mould (Fig. 5,6 latexcast of internal mould), AMNH 45006, Belén Formation, upper member (Eifelian), Chacoma, La Paz Department,Bolivia (coIl.L. Branisa), dorsal, anterior, oblique, posterodorsal, ventral cephalon, ventral pygidium, and left lateralviews, x 4.1-7. Carapace dorsale, moule interne, (Fig. 5, 6,moulage en latex du moule interne), vues dorsale, antérieu-re, oblique, dorsale-postérieure, ventrale du cephalon, ventrale du pygidium, et latérale.

more material would be required for comprehensivedescription.

Subfamily uncertàinGenus Malimanaspis BALDIS& LONGOBUCCO,

1977Synonym - Goodsiraspis ADRAIN& CHATTERTON,1993

Type species -Malimanaspis sarudianskii BALDIS& LONGO-BUCCO,1977, ChavelaFormation(Givetianor Frasnian),nearMaliman,SanJuan Province,Argentina.Other species -Malimanaspis angustilimbata PEK& VANEK,1991, BelénFormation,Eifelian,Chacoma,LaPazDepartment,Bolivia ; Harpidella butorus HOLLOWAY,1980, St. ClairLimestone,Wenlock,Arkansas,U.S.A.;Cyphaspis novella BAR-RANDE,1852, KopaninaFormation,Ludlow,CzechRepublic;Goodsiraspis packardi ADRAIN& CHATTERTON,1993, BarlowInletFormation,Ludlow,centralCanadianArctic.Diagnosis (emended from diagnosis ofGoodsiraspis, Adrain & Chatterton 1993, p. 1637) -Very large L1 ; prominent bicomposite eye ridge;librigena with variably developed but usually sub-dued bilobate eye socle and broad field; genal spineshort, nearly triangular, with broad, flattened base;transverse, subtrapezoidal rostral plate withconnective sutures widely separate posteriorly ;thorax of 13 or 14 segments, lacking axial spine;pygidium with width twice length, five or six axialrings, and only first one or two ring, pleural, andinterpleural furrows well impressed.Discussion - Malimanaspis has previously beenknown from two internal moulds, each the holotypeof one ofthe two assigned species. New and somew-hat better material now available shows the unex-pected presence in the species M. angustilimbata ofa short, transverse rostral plate with connectivesutures widely separate posteriorly (PI. 58, fig. 5),and of short, triangular, and flattened genal spines(pI. 58, fig. 3). Both are odd for an ß-ulacopleurid(although a similar, but very obviously non-homolo-gous, modification of the genal spines occurs, forexample, in Maurotarion isaacsoni, above), andwere two of the key diagnostic criteria for therecently erected Goodsiraspis ADRAIN& CHATTER-TON,1993, which had as type a Ludlow species fromfar northern Canada (G. packardi). Despite greatdifferences in age (Eifelian versus Ludlow), geogra-phical occurrence (central South America versusArctic Canada), and habitat (shallow subtidal ver-sus monospecific, deep water assemblage), Malima-naspis angustilimbata and G. packardi are excee-dingly similar to one another, share several derivedfeatures, and other, closer, relatives for each taxoncannot be identified. Goodsiraspis, therefore, isconsidered a junior subjective synonym ofMalimanaspis.Adrain & Chatterton (1993) listed several additio-nal species possibly belonging to Goodsiraspis.Given the additional diversity, the species butorus

433

HOLLOWAY,1980, and novella BARRANDE,1852, canbe assigned with considerable confidence toMalimanaspis. The lectotype of the species beyrichiNovAK, 1890, which Adrain & Chatterton conside-red possibly, but not definitely, related toGoodsiraspis, has a sagittal profile (Alberti 1970, pI.9, fig. 15) indicating that it almost certainly belongsto the aulacopleurine genus Aulacopleura HAWLE&CORDA,1847 (as revised by Adrain & Chatterton1995a).Adrain & Chatterton (1993) argued that resem-blances between Goodsiraspis and aulacopleuridswere convergent, and that the genus should be assi-gned to the family Rorringtoniidae Owens in Owens& Hammann (1990). This remains a possibility, butthe three-dimen~ionally preserved Devonian spe-cies are even more aulacopleurid-like. Holloway(1994) has criticized the rorringtoniid hypothesis,contesting the significance of the features cited byAdrain & Chatterton (1993), and presenting hisown list of morphological features, in an attempt todemonstrate close relationship between Malima-naspis and Maurotarion. The latter can be dismis-sed forthwith ; Malimanaspis shares none of theapomorphies of Maurotarion as established byAdrain & Chatterton (1995b) and reiterated above.All of the features listed by Holloway (1994, p. 246)are very general, most related to dimensiqns ofexoskeletal features, and all are distributed widelythrough the Aulacopleuridae and both of its subfa-milies. As examples, the "moderate cranidialconvexity" is seen also in all aulacopleurines ; the"relatively short (sag.) preglabellar field" is no diffe-rent in relative dimensions from that of most spe-cies of either Harpidella or Otarion, and is in factmuch longer than that of most species of Cyphaspis;the exsagittal midlength of the eye is opposite theanterior of L1 in virtually every otarionine ; and a"pygidium with the axis as wide anteriorly as thepleurae" is seen in most species of Harpidella. Inshort, not a single "character" listed by Hollowaycan be construed as a synapomorphy unitingMalimanaspis and Maurotarion.As regards the features of Malimanaspis conside-red by Adrain & Chatterton (1993) to support assi-gnment to Rorringtoniidae, and Holloway's (1994)criticism thereof, the following points can be made :1. In light of the new material described herein,some of the features listed by Adrain & Chattertonare rendered considerably more ambiguous.Whereas the genal spine ofM. packardi is withoutquestion subtriangular and not of the typical, cylin-drical aulacopleurid morphology, the Maurotariondereimsi group demonstrate that a subtriangularcheek evolved within Otarioninae at least once, andthe genal spine ofMalimanaspis angustilimbata isevidently subcylindrical. Secondly, whereas the S2ofMalimanaspis angustilimbata is relatively deep,

it is nowhere near as pronounced as that ofM. pac-kardi, and well within the range of accepted aula-copleurids. Finally, the librigena ofM. angustilim-bata bears a prominent, bilobate eye socle, verysimilar to the general and primitive aulacopleuridcondition. Holloway (1994,p. 247) opined that "...thesocle in Rhinotarion is not bilobate either but paral-lel-sided ...indicating that a bilobate socle is not asynapomorphy ofAulacopleuridae ...." Although themorphology of M. angustilimbata renders thisobservation irrelevant, it should be noted that themorphology of the structure in a late and highlyevolved representative has no bearing on its primi-tive state within the family. A bilobate eye socle isalmost certainly a synapomorphy of Aulacopleuri-dae. Subsequent evolution from this condition (e.g.,effacement in Maurotarion ; reduction to a narrowband in Harpidella) is important only in the contextof ingroup structure.2. Despite the above points, the transverse rostralplate of Malimanaspis remains without precedentin the family Aulacopleuridae, as nearly everysingle other species known has a small, triangularform with the connective sutures almost meetingposteriorly. Holloway (1994, p. 246) contested thisassertion : "The rostral plate does not taper to apoint posteriorly in all aulacopleurids ...."Adrain &Chatterton (1993) nowhere claimed that it did. Theonly counter-evidence provided by Holloway (1993,p. 246) is the following: "...in Rhinotarion (seeWhittington & Campbell, 1967, pI. 4, fig. 11) andpossibly also Maurotarion axitiosum (Campbell,1977 : 16, pI. 3, fig. 2c), the posterior ends of theconnective suture are widely separate, as inGoodsiraspis." It is instructive to note that the onlydefinite counterexample cited is an otarionine spe-cies with a unique, highly modified, rostral area.Harpidella sentosa (see Adrain & Chatterton,1995b, for the synonymy of Harpidella and themonotypie Rhinotarion) has a large, prong-likeanterior extension of its medial anterior border. Itsrostral plate has a matching anterior extension, andthe entirety of the rear of the plate is shifted for-ward relative to that ofother otarionines. The resultis that the connective sutures are elongate and runalmost transversely, and the sagittal area of theposterior margin is indeed wider than normal, butonly because it is seemingly compensating for thewidth of the autapomorphic anterior extension.While the morphology of the rostral plate ofH. sen-tosa is certainly in conflict with Adrain &Chatterton's (1993, p. 1637) assertion that all aula-copleurids have a small, triangular rostral plate, itis equally obvious that it is an autapomorphic deri-vative of a small, triangular rostral plate. It cer-tainly bears no detailed similarity to the rostralplate of Malimanaspis, which is very short (sag.,exsag.), does not bear a prong-like median exten-

434

sion, and has short, obliquely inclined, versus longand transverse, connective sutures. Given thatthere is no possibility of a shared, independent ori-gin of the two plate types, the morphology of theotarionine H. sentosa rostral plate has no bearingwhatever upon the relationships ofMalimanaspis.In sum, Malimanaspis (=Goodsiraspis) is nearlyimpossible to relate to any well understood aulaco-pleurid in what could be construed as synapomor-phic detail. At present, the only conceivable compa-rison is with the otarionine genus HarpidellaMcCoy, 1849 (as revised by Adrain & Chatterton1995b), with which Malimanaspis shares similarcranidial dimensions, particularly in sagittal profi-le, and also large, laterally displaced LI.Whetherthese features represent synapomorphies is unk-nown. Species of Harpidella differ from those ofMalimanaspis in the shape of the rostral plate andin the presence versus absence (in all cases forwhich information is available) of a thoracic axialspine. There is simply not enough information atpresent to assess the affinities of Malimanaspiswith confidence,particularly in the absence of onto-genetic data (which has proven invaluable in anongoing revision of Aulacopleuridae ; Adrain &Chatterton 1994, 1995a, 1995b). The taxon mightpotentially (but not certainly) belong to Aulaco-pleuridae, but its generic affinity and subfamilialassignment are unknown.

Malimanaspis angustilimbata PEK&VANEK,1991PI. 56, figs. 4, 6-8,12; PI. 57, figs. 5, 6, 8-12; PI. 58, figs. 1-7

1968 Otarion dereimsi (KOZLOWSKJ); Wolfart, p.56, pU,figs. 1a-e.

1979 Otarion nov. sp. ; Eldredge & Ormiston, p. 165.1991 Malimanaspis angustilimbata PEK & VANEK, p.78,

PI. 6, figs. 2, 3.

Material and Occurrence - Topotypes AMNH 45005 and45006, from the upper member of the Belén Formation (Eifelian),Chacoma, La Paz Department, Bolivia ; assigned specimensAMF 92955, from glacial rubble near Lahuachaca, La PazDepartment, presumably from the Belén Formation, AMF92954, from an undetermined stratum (presumably BelénFormation), Pujravi, La Paz Department. The most preciselylocalized specimen of this taxon is a cranidium figured byWolfart (1968) frOll the "comutus Zone" at Pujravi. In Wolfart's(1968) stratigraphic scheme, this is the lower part of the upperllember of the Belén Formation.

Diagnosis - Malimanaspis with moderate sizeddorsal cranidial tubercles; subdued median occipi-tal node ; thorax of 13 segments ; thoracic axiallings with faint median tubercle and very subduedtransverse tubercle row ; pygidium with four welldefined axial rings, and faint fifth.Description -Malimanaspis angustilimbata is sosimilar to M. packardi (ADRAIN& CHATTERTON,1993)that description is best accomplished throughan extended differential diagnosis :

Anterior border apparently shorter (sag. ; exsag.);median node absent from preglabellar field; pregla-bellar field and frontal area with sculpture of even-ly scattered small tubercles; S2 narrower (tr.),muchshallower, and in contact with axial furrow distally;median glabellar lobe and L1 with sculpture of rei a-tively dense, moderate sized tubercles; median occi-pital tubercle more prominent, but transverse row ofsmall tubercles on occipital and thoracic axial ringsmore subdued; librigenal field tuberculate ; biloba-te eye socle much better expressed ; thorax of 13segments, versus 14; thoracic axial lobe approxima-tely equal in width to pleural lobe,versus much nar-rower; pygidium shorter (sag.) relative to width, dueto reduced post-axial area.Discussion - Pek and Vanek (1991, p. 78)reported12 thoracic segments for their single holotype spe-cimen. This cannot be confirmed from their illustra-tions. The number of segments can be counted withcertainty on three of the four specimens figuredherein, and in these cases at least is definitely 13.Baldis & Longobucco (1977) reported the segmentcount ofthe single specimen ofMalimanaspis saru-dianskii as "twelve or thirteen," but again theactual number is difficult to verifY from the publi-shed illustrations. This specimen was reported to bein the Museo Argentino de Ciencias Naturales"Bernardino Rivadavia" (confirmed by RA. Baldis,pers. comm., December 1993), but a search of thecollections by G.D.E. in May 1993, failed to locate it.N. Cabaleri (pers. commun., 1994) reports that onlya very poorly preserved cast is available.Malimanaspis angustilimbata is distinguishedfrom the type species, M. sarudianskii (in as muchas the latter is known), in the possession of largerLI ; less robust dorsal cranidial tuberculation ;much less prominent occipital and thoracic axialtubercles; thorax with 13 versus "12 or 13" seg-ments ; and a pygidium that is seemingly wider (tr.)relative to its length (sag.).

Malimanaspis sp.Pl. 56, figs. 10, 11, 13

Material and Occurrence - Figured specimen MHNC 8114,from the upper third of the lower member of the BelénFormation (probablyEmsian), Chiarumani, La Paz Department,Bolivia.

Discussion - A single small specimen ofMalimanaspis is preserved with the posterior partof the external mould containing hard siliceousinfilling, obscuring detail. The specimen does seemspecifically distinct from the younger M. angusti-limbata in its smaller L1, more arcuate preglabellarfurrow, less obvious tuberculate sculpture, and par-ticularly very short (exsag.) eye and palpebral lobe.These differences could be partly due to preserva-tion, however, and detailed comparison is scarcelypossible.

435

Acknowledgements - We are grateful to P.R. Racheboeuf forallowing us to study specimens collected by him and for provi-ding detailed age and locality data. L. Smith provided G.D.E.with goodcompany and guidance to Bolivian sections in 1992,and donated several important specimens collectedby him. Thefollowingindividuals kindly gave curatorial assistance, includingarranging loans of specimens in their care: M.Dorling (SMC) ;N. Eldredge (AMNH); Y Gayrard (MNHN) ; R. Suarez-Soruco(MHNC); and J. Thompson (USNM).Costs of technical prepara-tion were met by a Natural Sciences and Engineering ResearchCouncil (Canada) operating grant to A.C. Lenz. We thank P.Morzadecfor review of the manuscript. This is FACPACcontri-bution n° 4.

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J.M. ADRAIN & G.D. EDGECOMBEDepartment of PalaeontologyThe Natura! History Museum

Cromwell RoadLondon SW7 5BD, United Kingdom

andDivision of Earth and Environmental Sciences

Australian Museum6 College Street

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