David J. Holloway

The Trilobite Reedops (Phacopidae) in the Lower Devonian of Argentina (Malvinokaffric Realm)

Abstract The trilobite Reedops is documented from strata probably corresponding to the middle part of the Talacasto Formation in the Sierra de las Minitas, at the northernmost extent of the Precordillera in La Rioja Province, northwestern Argentina. The specimens resemble the type species of the genus, R. bronni, indicating a Pragian (Early Devonian) age for the strata, and suggesting the occurrence at this time of faunal exchange between the Old World Realm, particularly the Bohemian area, and the Malvinokaffric Realm. The taxon represents the first Early Devonian macrofaunal element in the Malvinokaffric Realm with global biostratigraphical significance.

The trilobiteProtostygina and the composition of the Styginidae, with two new genera

The Styginidae is regarded as an exclusively Ordovician family of trilobites, separate from the Scutelluidae. The hitherto poorly known genusProtostyginaPrantl &Přibyl, 1949 is revised. It is recorded with certainty only from the Llanvirn of the Czech Republic, and the type species is a senior synonym of“Raymondaspis” rubensi rubensiPřibyl &VANěK, 1968 and“R.” rubensi lybarŠnajdr, 1976. Two new styginid genera are proposed:Cyrtocybe, with type species“Raymondaspis” turgidaWhittington, 1965, is known from the upper Arenig and lower Llanvirn of Newfoundland, Maine and Norway; andPromargo, with type speciesP.forteyi n. sp., occurs in the Arenig of Newfoundland and Spitsbergen.TurgicephalusFortey, 1980 is regarded as a junior synonym ofRaymondaspisPřibyl inPrantl &Přibyl, 1949. Three genera are excluded from the Styginidae:KirkdominaTripp, 1962,PseudostyginaZhou inZhou et al., 1982 andStyginellaPřibyl &Vaněk, 1971.KurzfassungDie Styginidae wird als eine ausschließliche ordovizische Familie von Trilobiten angesehen, getrennt von der Scutelluidae. Die bisher wenig bekannte GattungProtostyginaPrantl &Přibyl, 1949 wird revidiert. Sie ist mit Sicherheit nur aus dem Llanvirn der Tschechischen Republik bekannt, und die Typusart ist ein älteres Synonym von„Raymondaspis“ rubensi rubensiPřibyl &Vaněk, 1968 und„R.“ rubensi lybarŠnajdr, 1976. Zwei neue Gattungen von Styginidae werden eingeführt:Cyrtocybe, mit der Typusart„Raymondaspis“ turgidaWhittington, 1965, ist vom oberen Arenig und unteren Llanvirn von Neufundland, Maine und Norwegen bekannt; undPromargo, mit der TypusartP.forteyi n. sp., tritt im Arenig von Neufundland und Spitsbergen auf.TurgicephalusFortey, 1980 wird als jüngeres Synonym vonRaymondaspisPřibyl inPrantl &Přibyl , 1949 angesehen. Drei Gattungen werden aus den Styginidae ausgeschlossen:KirkdominaTripp, 1962,PseudostyginaZhou inZhou et al., 1982 undStyginellaPřibyl &Vaněk, 1971.

Phylogeny of some Devonian trilobites and consequences for the systematics of Austerops (Phacopidae)

A comprehensive phylogenetic hypothesis for Devonian phacopid trilobites of the genus Austerops has not previously been proposed. We carried out a cladistic analysis of the 13 species and subspecies assigned to Austerops, based on a data matrix of 63 characters. Two species of the morphologically very similar genus Chotecops, C. auspex and C. hoseri, and seven other close relatives (Reedops cephalotes hamlagdadianus, Boeckops stelcki, Morocops granulops, Paciphacops logani, Phacops latifrons, Phacops araw and Pedinopariops (Hypsipariops) vagabundus) were also included in the analysis in order to test their relationship with species of Austerops. Parsimony analyses using a heuristic method, with Calyptaulax callirachis and C. glabella as outgroup taxa, produced two most parsimonious trees of 341 steps. These trees are partly consistent with trees obtained from additional analyses performed with modified data sets (deletion of homoplastic characters, multistate characters, continuous characters carved into 5% increments, thoracic and pygidial characters, or taxa with numerous unknown characters). Results suggest that Austerops sp. B and A.? sp. D are close to Chotecops hoseri and C. auspex, and that these species constitute a monophyletic group. Austerops Austerops menchikoffi, A. speculator and A. punctatus are also a monophyletic group and reasonably constitute a sister group of that formed by the rest of Austerops and Chotecops sensu lato, while A. hottonensis seems phylogenetically distant from other representatives of Austerops. Chotecops including C. hoseri and C. auspex together with Austerops sp. B and A.? sp. D seem derived from A. legrandi. The relationship between Austerops and Chotecops remains partly unresolved but it seems likely that their recognition as separate taxa results in paraphyletic groups. The phylogenetic analysis suggests that the currently poorly known Austerops sp. B and A.? sp. D should be reassigned to Chotecops.

Trilobites of the suborder Illaenina from the Silurian of north Queensland, Australia

Abstract. The trilobite fauna of the middle Silurian (Telychian to possibly earliest Sheinwoodian) Tomcat Creek limestone in the Broken River Province of north Queensland is dominated by the suborder Illaenina, including illaenimorphs (Illaeninae and Bumastinae) and members of the Scutelluidae. Scutelluidae are most diverse, with eight genera, of which Dolabrapex, Iotoryx, Perizostra, and Quintonia are new. Perizostra is the first scutelluid with a cephalon that may be described as of phacomorph appearance. Illaenimorphs are represented by three genera, including Opsypharus, which is regarded as a senior synonym of Paracybantyx but distinct from Failleana with which it has been placed in synonymy by some authors. Thirteen species are new: Cybantyx? ergodes, Opsypharus pandanensis, Australoscutellum talenti, Dolabrapex acomus, Illaenoscutellum psephos, Iotoryx clarksoni, Japonoscutellum mawsonae, J. drakton, J. fractum, Kosovopeltis avita, Perizostra campbelli, Quintonia arata, and Q. pavo. A species of Stenoparia is placed in open nomenclature. The species of Australoscutellum, Illaenoscutellum, and possibly Kosovopeltis are the oldest known representatives of those genera. These genera and Japonoscutellum are also common in faunas from limestones of Wenlock to Ludlow age in central western New South Wales, reflecting the similarity in lithofacies. The monotypic Late Ordovician genus Craigheadia, which has been regarded as a scutelluid, belongs to the Lichidae and is probably a junior synonym of Leiolichas.

The trilobite generaEocryphops andPlagiolaria (Phacopidae)

Eocryphops andPlagiolaria are revised and a new species,E. albertii, is described from the Eifelian of Morocco.“Trimerocephalus” cyclophthalmusWalther, 1907, a species long assigned toEocryphops, is regarded as a junior subjective synonym of the type species ofPlagiolaria, Pl, plagiophthalma. Eocryphops originated in the evolutionary lineage leading toPhacops (s.str.), whereasPlagiolaria was probably derived fromLochkovella. Although they have been linked with the Late Devonian group of small-eyed and blind phacopids includingCryphops and its relatives. neitherEocryphops norPlagiolaria is ancestral to these forms. Confirmed occurrences ofEocryphops andPlagiolaria are from regions that were situated on the North Gondwana margin or on plates associated with this margin.KurzfassungEocryphops undPlagiolaria werden revidiert und eine neue Art,E. albertii, aus dem marokkanischen Eifelium beschrieben.„Trimerocephalus“ cyclophthalmusWalther, 1907, eine Art, die lange Zeit zuEocryphops gestellt wurde, wird as jüngeres subjectives Synonym der Typus-Art vonPlagiolaria, PI. plagiophthalma, angesehen.Eocryphops kommt aus der zuPhacops (s.str.) führenden Evolutionsreihe, währendPlagiolaria wahrscheinlich vonLochkovella herkommt. Obwohl sie mit der spätdevonischen Gruppe klein-äugiger und blinder Phacopiden inclusiveCryphops und Verwandte in Verbindung gebracht wurde, sind wederEocryphops nochPlagiolaria als deren Ahnformen anzusehen. Bestätigte Vorkommen vonEocryphops undPlagiolaria sind von Gebieten, die am Nordrand von Gondwana oder auf damit assoziierten Platten lagen.