Panochthus subintermedius was originally named by Castellanos in 1933, without any diagnosis and no type material designated. In 1936, he briefly described and designated a holotype for this species and subsequently, in 1942, completed the description, but a diagnosis was still lacking. Some authors have considered this species as nomem nudum, but others have accepted its validity since 1942. In this contribution we propose that Castellanos's 1936 paper is the valid nameestablishing publication for this species. The holotype includes a large portion of dorsal carapace, the caudal tube, and remains of postcranial skeleton, belonging to a single specimen from the Ensenadan Stage/Age (early-middle Pleistocene) of Buenos Aires, Argentina. In contrast to the original description, new observations of the holotype reveal that the superficial surface of the dorsal carapace osteoderms is ornamented with small polygonal figures without a principal one. This ornamentation differs from that of P. intermedius Lydekker (the only species accepted up to now for the Ensenadan), with a central figure in most of its osteoderms. The caudal tube of P. subintermedius differs from those of the Bonaerian-Lujanian species (middle late Pleistocene-early Holocene), in having a sharper distal end, one apical dorsal figure, and a higher number of central figures along the entire dorsal surface. No caudal tube associated with the carapace of P. intermedius is known. Accordingly, P. subintermedius can be clearly distinguished from other Panochthini species by a unique combination of carapace and caudal tube characters. This new combination of characters provides more information on this taxon and other species of Panochthini for future studies in the interrelationships of Glyptodontia. KeywordsGlyptodontia Á Panochthini Á Panochthus Á Ensenadan Á Argentina Á South America Kurzfassung 1933 benannte Castellanos Panochthus subintermedius ohne eine Diagnose zu machen oder Typusmaterial festzulegen. Im Jahr 1936 folgten vom selben Autor eine kurze Beschreibung und die Definition des Holotypus (MACN-Pv 5130). Später, im Jahre 1942, schloss Castellanos die Beschreibung ab ohne eine Diagnose zu stellen. Einige Autoren betrachten diese Art als nomen nudum, während andere ihre Gültigkeit seit 1942 akzeptieren. In diesem Beitrag plädieren wir dafür, die Gültigkeit der Artbezeichnung Castellanos (1936) anzuerkennen. Der Holotypus umfasst einen großen Teil des dorsalen Panzers, der kaudalen Knochenscheide und einige Postcranialelemente von einem einzigen Exemplar aus der Ensenada-Stufe (frühes Mittel-Pleistozän) von Buenos Aires (Argentinien). Im Gegensatz zu der ursprünglichen Beschreibung weisen neue Beobachtungen am Holotypus kleine Polygone ohne Zentralstruktur auf den Osteodermen an der dorsalen Oberfläche des Panzers auf. Diese Ornamentierung unterscheidet sich von P. intermedius (LYDEKKER), die bis heute einzige bekannte Art aus dem Ensenadan, indem diese eine Zentralstruktur in den meisten Osteodermen aufweist. Die kaudalen Knochenscheiden von P. ...

To test the monophyly of Panochthini, a phylogenetic analysis including all the species traditionally referred to the tribe was conducted. The matrix included 16 species of Glyptodontidae and 35 characters, from which 14 correspond to the skull, four to the dentition, two to the cephalic armour, nine to the dorsal carapace and six to the caudal sheath. Propalaehoplophorus australis (Propalaehoplophorinae) was used to root the trees. Four most parsimonious trees were obtained (Tree Length = 75, CI = 0.65, RI = 0.70). The strict consensus tree (Tree Length = 77, CI = 0.64, RI = 0.68) has the following topology: Propalaehoplophorus australis (Glyptodon reticulatus (Hoplophorus euphractus (Panochthus jaguaribensis, P. intermedius (P. frenzelianus, P. tuberculatus (P. subintemedius, P. greslebini)))) ((Pseudoplohophorus absolutus, Plohophorus figuratus) (Nopachtus cabrerai, N. coagmentatus, Propanochthus bullifer, Stromaphorus compressidens, Phlyctaenopyga ameghini))). The results indicate that: 1, Panochthini is not a natural group but polyphyletic; 2, Panochthus is monophyletic and, concordant with recent proposals, Hoplophorus euphractus is its sister group; and 3, Nopachtus and Propanochthus are more closely related to species traditionally referred to 'Plohophorini' than to Panochthus. Nopachtus and Propanochthus, as the 'Plohophorini', are recorded from the latest part of the Neogene, whereas Panochthus and Hoplophorus euphractus are restricted to the Quaternary.

Revision of the genus Nopachtus Ameghino and Phlyctaenopyga Cabrera (Xenarthra, Glyptodontidae, Hoplophorinae) from the late Miocene and Pliocene of Argentina. This work presents the first formal diagnosis for two genera of Hoplophorinae glyptodons, Nopachtus and Phlyctaenopyga, as well as for the species they incluye. In addition, a new species of Nopachtus is recognized for the Montehermosan, and a new combination is proposed: Phlyctaenopyga trouessarti. Precise geographical and stratigraphic provenance is provided for all the analyzed taxa. The most significant differences between Phlyctaenopyga and Nopachtus lie in the osteoderms, especially in the degree of convexity of the central figures and the number of peripheral figures that surround them. Although the central figure is convex in both genera, it is more "bulbous"/ "bubble-shaped" in Phlyctaenopyga compared to Nopachtus. Lastly, in Phlyctaenopyga the peripheral figures are arranged in two or three rows, with 18 to 23 figures in the first row. In the genus Nopachtus there are never more than two rows peripheral figures, and the first one comprises 12 figures.Key words: Hoplophorinae, Nopachtus, Phlyctaenopyga, Mio-Pliocene, Argentina.Resumen: En esta contribución se presentan por primera vez diagnosis formales de dos géneros de gliptodontes Hoplophorinae, Nopachtus y Phlyctaenopyga, así como de las especies que incluyen. Se reconoce además, para el Montehermosense, una nueva especie de Nopachtus y se plantea una nueva combinación: Phlyctaenopyga trouessarti. Asimismo, se precisa la procedencia geográfica y estratigráfica de los taxones aquí analizados. En este sentido, las diferencias más significativas entre Phlyctaenopyga y Nopachtus se encuentran a nivel de los osteodermos, principalmente en el grado de convexidad de la figura central y al observar el número de figuritas periféricas que rodean a ésta. Si bien en ambos géneros la figura central es convexa, en Phlyctaenopyga es más "ampollada" que en Nopachtus. Por último, en el caso de Phlyctaenopyga, las figuritas periféricas están dispuestas en dos o tres hileras, presentando la primera de 18 a 23 figuritas. En el género Nopachtus nunca hay más de dos hileras y la primera, presenta 12 figuritas periféricas.

RESUMENPanochthus es uno de los géneros de gliptodóntidos de mayores dimensiones y más ampliamente registrado en el Pleistoceno del sur de América del Sur. Una reciente revisión demostró que alberga seis especies distribuidas cronológicamente de la siguiente manera: P. intermedius y P. subintermedius (Pleistoceno tempranoPleistoceno medio, Ensenadense); P. tuberculatus y P. frenzelianus tienen sus biocrones limitados al Pleistoceno medio-Pleistoceno tardío (Bonaerense-Lujanense), mientras que P. greslebini y P. jaguaribensis solo pueden referirse al Pleistoceno sensu lato. En la presente contribución se da a conocer el registro más antiguo de Panochthus, representado por el material MMP 5171, procedente del Plioceno tardío (Aloformación Playa Los Lobos, Formación Chapadmalal; Chapadmalalense; Biozona de Paraglyptodon chapalmalensis) de la localidad de Mar del Plata, Buenos Aires, Argentina. El material consiste en un gran fragmento de coraza dorsal y en varios trozos de osteodermos asociados, asignables a una especie indeterminada de Panochthus. Uno de los caracteres más significativos es la presencia, a nivel de la superficie expuesta de los osteodermos, de figuritas que siguen un evidente patrón reticular, solo observable en Panochthus. Desde el punto de vista bioestratigráfico, es llamativa la ausencia de registros de Panochthus en la Edad Marplatense (Plioceno tardío-Pleistoceno temprano).Palabras clave: Panochthus; Chapadmalalense; Plioceno; Pleistoceno; Argentina ABSTRACTPanochthus is one of the largest sized and most frequently recorded genera of Pleistocene South American Glyptodontidae. A recent taxonomic revision shows that the genus includes six species: P. intermedius and P. subintermedius (early Pleistocene-middle Pleistocene), P. tuberculatus and P. frenzelianus (middle Pleistocene-late Pleistocene), whereas P. greslebini and P. jaguaribensis only can be referred to the Pleistocene sensu lato. In this contribution the oldest record of the genus Panochthus (MMP 5171) is presented and described. The remains came from the late Pliocene (Playa Los lobos Aloformation, Chapadmalal Formation; Chapadmalalan; Paraglyptodon chapalmalensis Biozone) of the Mar del Plata, Buenos Aires province, Argentina. The material is represented by a considerable fragment of dorsal carapace and some associated osteoderms, which are assignable to an indeterminate species of Panochthus. One of the most significant characters in the exposed surface of the osteoderms is the presence of a clear "reticular" pattern, a character only observed in Panochthus. From a biostratigraphic viewpoint, it is remarkable the absence of records of Panochthus in the Marplatan Age/Stage (late Pliocene-early Pleistocene).

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