Institutional abbreviations.
AMNH, American Museum of Natural History, New York, USA; CC-MUFCA, Colección “Dr. Alfredo Castellanos”, Museo Universitario “Florentino y Carlos Ameghino”. Facultad de Ciencias Exactas, Ingeniería y Agrimensura - Universidad Nacional de Rosario. Rosario. Santa Fe, Argentina; FACENA, Facultad de Ciencias Exactas y Naturales y de Agrimensura, Corrientes Capital, Argentina; FC-CVF, Colección de vertebrados fósiles, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay; FMNH-P, Field Museum of Natural History, Paleontological collection, Chicago, Illinois, USA; GCF, Grupo Conservacionista de Fósiles, Museo Paleontologico ‘Fray Manuel de Torres,’ San Pedro, Buenos Aires, Argentina; IGM, Instituto de Geología, Universidad Nacional Autónoma de México, Ciudad Universitaria, México; MACN, Sección Paleontología Vertebrados, Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”, Buenos Aires, Argentina; MCA, Museo Municipal de Ciencias Naturales ‘Carlos Ameghino,’ Mercedes, Buenos Aires, Argentina; MCH P, Sección Paleontología, Museo Arqueológico Condor Huasi, Belén, Catamarca, Argentina; MHNC, Museo de Historia Natural de Cochabamba ‘Alcide d’Orbigny’, Cochabamba, Bolivia; MLP-PV, División Paleontología Vertebrados, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Buenos Aires, Argentina; MMC, Museo Municipal de Colonia ‘Dr. Bautista Rebuffo’, Colonia de Sacramento, Uruguay; MMP, Museo Municipal de Ciencias Naturales ‘Lorenzo Scaglia’ Mar del Plata, Argentina; MSM, Arizona Museum of Natural History (formerly Mesa Southwest Museum), Arizona, USA; PVL, Colección de Paleozoología de la Facultad de Ciencias Naturales e Instituto ‘Miguel Lillo’, San Miguel de Tucumán, Argentina; PVSJ, Instituto y Museo de Ciencias Naturales, Universidad Nacional de San Juan, San Juan (San Juan Province, Argentina); Pz-Ctes, Colecciones Paleontológicas de la Universidad Nacional del Nordeste “Rafael Herbst”, Corrientes, Argentina; SGO PV, vertebrate paleontology collections, Museo Nacional de Historia Natural, Santiago, Chile; UCMP, University of California, Museum of Paleontology, Berkeley, California, USA; UFMG, Museo de la Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
Anatomical abbreviations.
bc, bony crest; dpm, descending process of the maxillae; fm, foramen magnum; if, infraorbital foramina; Mf, mf, upper and lower molariforms; no, nasal opening; oc, occipital condyle; on, orbital notch; sc, sagittal crest; za, zygomatic arch.
Other abbreviations.
FAD, First Appearance Datum; FOCP, Faldeo Occidental Cerro Pampa; LAD, Last Appearance Datum; Ma, Megaannun, (millon years ago); PCQ, Puerta de Corral Quemado; SFN, San Fernando Norte; SMV, Santa María Valley; VQB, Villavil-Quillay Basin.
The most relevant materials for this study are housed in the paleontological collection of vertebrates from the Museo de La Plata (“Cabrera collection”) and the Paleontological collection from the Field Museum of Natural History (Riggs collection), under the following acronyms: skulls, MLP-PV 29-X-8-1, MLP-PV 29-X-10-1, FMNH-P14396; mandibles, MLP-PV 16–138, MLP-PV 29-X-8-1; carapaces MLP-PV 16–101, MLP-PV 29-X-10-2, FMNH-P14439; caudal tubes, MLP-PV 29-X-8-9, MLP-PV 29-X-10-1, FMNH-P14414, FMNH-P14532; (see Online Resource 1 for the nomenclatural history of Phlyctaenopyga ameghini (Ameghino, 1889) and Stromaphorus compressidens (Moreno y Mercerat, 1891); and Online Resource 2 for a list of all materials assigned to the species Stromaphorus ameghini (Ameghino, 1889; ex Moreno, 1882).
A comparative study was carried out to obtain a morphological characterization of the specimens, including cranial and postcranial elements. The results are shown in the anatomical descriptions. For direct comparison, specimens referred to the following genera were used: Glyptodon Owen, 1839; Kelenkura Barasoain, Zurita, Croft, Montalvo, Contreras, Miño-Boilini and Tomassini, 2022; Plohophorus Ameghino, 1887; Pseudoplohophorus Castellanos, 1926; Cranithlastus Arias, Alonso and Malanca, 1978; Stromaphoropsis Kraglievich, 1932; Eleutherocercus Koken, 1888; Doedicurus Burmeister, 1874; Neosclerocalyptus Paula Couto, 1957; Eosclerocalyptus Ameghino, 1919; Hoplophorus Lund, 1839; Nopachtus Ameghino, 1888; Propanochthus Castellanos, 1925; Panochthus Burmeister, 1866. Additionally, specimens from the literature were included in the analysis.
All measurements referred to in the text are listed in Online Resource 3 (table 1: skull; table 2: Holotype MLP-PV 16–101; table 3: carapace, and table 4: caudal tube); they were taken through a manual "Vernier" caliper, with an error range of 0.5mm and in some cases using ImageJ (1.53e) software. The linear dimensions are expressed in millimeters (mm). For descriptions and comparisons of the dorsal carapace, osteoderms and caudal tube, we follow the proposal of Zamorano et al. (2011), Porpino et al. (2014) and Toriño (2015). The numbering assigned to the figures of the ornamentation of caudal tubes (see Fig. 7) follows the proposal of Toriño (2015), and Toriño and Perea (2018). For chronological purposes, we follow the International Chronostratigraphic Chart v2022/02 (Cohen et al. 2020).
Cladistic analysis.
The phylogenetic study is based on a mixed matrix (see Online Resource 4 and Online Resource 5), consisting of a total of 96 characters, of which 95 are conventional (descriptive morphological characters) and one of geometric morphometry, to analyze a total of 35 taxa. The descriptive morphological characters are 68 binary and 27 multistate. This includes 40 skull characters, 4 autopodium characters, 26 carapace characters and 25 caudal armor characters. The information considered in this analysis, used both for the codification of states and landmark placement for geometric morphometry, was recorded via direct observation of the specimens and from photographs taken by the authors.
The taxon-character matrix was constructed with Mesquite version 3.4 (Maddison and Maddison 2018) and to build the geometric morphometric character, photographs were compiled into .tps files using tpsUtil software, version 1.70 (Rohlf 2016), and landmarks were digitalized with tpsDig2 version 2.16 (Rohlf 2010); this matrix was analyzed via “Traditional search“ under the criterion of maximum parsimony, using TNT version 1.5 (Goloboff and Catalano, 2016), the algorithm used was TBR (10 trees to save per replication). It is worth noting that all characters were unordered and were weighted equally (1.0). Clade support was assessed via Absolute and Relative Bremer support, retaining suboptimal trees by 3 steps; see Bremer (1994); Goloboff and Farris (2001). In addition, a Jackknife analysis was carried out via “Traditional search” (TBR algorithm) with 100 replicates and 36 removal probability. Finally, the consensus tree obtained from the two most parsimonious trees (MPTs) was calibrated to obtain estimated divergence times and potential ghost ranges. The calibration followed the ‘equal’ method (with a root of 1 million-years) implemented in the strap package (see Bell and Lloyd, 2014) for R software version 4.3.0 (R Core team 2023). The resulting time-scaled tree was plotted against the International Chronostratigraphic Chart (Cohen et al. 2020) for visualization purposes. The R commands included in the appendices of Bell and Lloyd (2014) and Toriño et al. (2021) were adapted for these procedures. The input data for the analysis with R were the strict consensus tree exported in parenthetical notation from TNT as a .tre file, and a txt file including a list of taxa with their first and last record (see supplementary files). The list of biochrons for each taxon as well as the bibliographical references from which this information was taken can be found in the Online Resource 6 of the present work.
The ingroup includes the following taxa: Boreostemma venezolensis Simpson, 1947; B. acostae (Villarroel 1983); Glyptodon jatunkhirkhi Cuadrelli, Zurita, Toriño, Miño-Boilini, Perea, Luna, Gillette and Medina, 2020; G. munizi Ameghino, 1881; G. reticulatus Owen, 1845; Glyptotherium texanum Osborn, 1903; Gl. cylindricum (Brown, 1912); Propalaehoplophorus australis Ameghino, 1887; Eucinepeltus petesatus Ameghino,1891; Cochlops muricatus Ameghino, 1889; Palaehoplophoroides rothi Scillato-Yané and Carlini, 1998; Palaehoplophorus meridionalis Ameghino, 1904; Kelenkura castroi Barasoain, Zurita, Croft, Montalvo, Contreras, Miño-Boilini and Tomassini, 2022; Plohophorus figuratus Ameghino, 1887; P. avellaneda Quiñones, Cuadrelli, De los Reyes, Luna, Poiré and Zurita, 2023; Pseudoplohophorus absolutus Perea, 2005; Ps. benvenutii (Castellanos, 1954); Stromaphorus ameghini (Ameghino, 1889); S. trouessarti (Moreno, 1888); Eleutherocercus solidus (Rovereto, 1914); E. antiquus (Ameghino, 1887); Doedicurus clavicaudatus (Owen, 1847); Neosclerocalyptus gouldi Zurita, Carlini and Scillato-Yané, 2008; N. ornatus (Owen, 1845); N. paseudornatus (Ameghino, 1889); N. paskoensis (Zurita, 2002); Nopachtus coagmentatus Ameghino, 1888; Hoplophorus euphractus Lund, 1839; Propanochthus bullifer (Burmeister, 1874); Panochthus intermedius Lydekker, 1895; P. tuberculatus (Owen, 1845) and Parapropalaehoplophorus septentrionalis Croft, Flynn and Wyss, 2007. The extant dasypodid Euphractus sexcintus Linnaeus, 1758, and the pampathere Pampatherium humdboltii (Lund, 1839) were used as outgroups to root the tree.
Geometric morphometrics.
For the geometric morphometric character (Fig. 2) two-dimensional coordinates of 29 landmarks were digitalized from photographs of mandibles in lateral view of sixteen glyptodonts (Eucinepeltus petesatus MACN 4760; Propalaehoplophorus australis MLP-PV 16 − 15; Pseudoplohophorus absolutus FC-CVF475-595; Glyptotherium texanum MSM 4818; Gl. cylindricum IGM 9563; Boreostemma acostae UCMP 38039; Glyptodon munizi GCF 10; G. reticulatus MCA 2015; Doedicurus clavicaudatus MACN 2762; Eleutherocercus solidus FMNH-P14437; Panochthus intermedius MHNC 13491; P. tuberculatus MLP-PV 16–29; Neosclerocalyptus ornatus MLP-PV 16–28; N. paskoensis MACN 18107; N. gouldi MCA 2010 and Parapropalaehoplophorus septentrionalis SGO PV 4165), one dasypodid (Euphractus sexcintus FACENA 183) and one pampatheriid (Pampatherium humboldtii MLP-PV 81-X-30-1); This method had previously been tested on Cingulate mandibles, with promising results in phylogenetics (see Nuñez-Blasco et al. 2021b). In this context, of the 29 landmarks, 5 are type I (Ladmarks 1, 10, 17, 18 and 19); 2 are type II (Ladmarks 2 and 3). Besides, there are 3 sets of semi-landmarks used to define the rest of the mandible morphology (green set, blue set and orange set). The green and blue sets (Fig. 2: a, c) were defined based on the 65º angle formed between landmarks 3, 19 and 10, subdividing it into 7 portions. The orange set (Fig. 2: b) was defined based on the 110º angle formed by landmarks 1, 3 and 19, subdividing it into 10 portions.
Geographic and stratigraphic context
The study area is in the Catamarca province, Northwestern Argentina, within the Northwestern Pampean Ranges geological province (Caminos, 1979). The Holotype materials of “Phlyctaenopyga” ameghini and “Stromaphorus compressidens” come from the Santa María Valley (SMV), while most of the fossils assigned to these two species come from the Villavil-Quillay basin (VQB).
The SMV (26°53’S, 66°05’W) is a tectonic depression of more than 100 km long by 20 to 30 km wide, flanked to the east by the Cumbres Calchaquíes and Aconquija Ranges, and to the west by the Quilmes Ranges (Bossi et al. 2001). A great part of the paleontological materials from SMV was exhumed from the Late Miocene/Pliocene levels cropping out at Andalhuala de Arriba and Tiopunco localities (Catamarca and Tucumán provinces, respectively). In turn, the VQB (27°15’ S/66°54’ W) is a tecto-sedimentary basin included in the Hualfin valley, limited to the northwest by the Sierra de Altohuasi, to the southwest by the Cerro Durazno, to the northeast by the Sierra de Hualfín, to the east by the Complejo Volcánico Farallón Negro, and the southeast by the Cerro Pampa-Belén Range (Fig. 1). The materials found in the VQB come from the Andalhuala, and Chiquimil formations cropping out at Puerta de Corral Quemado (PCQ), San Fernando Norte (SFN), and Faldeo Occidental del Cerro Pampa (FOCP).
The Neogene lithostratigraphic units recognized in these areas have been included in the Santa María Group, which is composed (from base to top) of Las Arcas, Chiquimil, Andalhuala, and Corral Quemado formations, ranging from ca. 10 to 3 Ma, being the Andalhuala Formation the most extended in both areas (Bossi et al. 1987; Muruaga 2001a, b; Bossi and Muruaga 2009; Bonini et al. 2017). The Andalhuala Formation in the VQB was deposited between ca. 7.14 to 3.66 Ma (Latorre et al. 1997), corresponding to the fossiliferous beds that yielded the studied materials (Riggs and Patterson 1939; Marshall and Patterson 1981). The historical specimens collected in the SMV lack provenance data, except for the reference of “Estratos Araucanos” (sensu Rovereto 1914) and “Araucanense medio” (sensu Castellanos 1948a, b, 1969), mainly assigned to the upper section of Chiquimil and Andalhuala formations in the modern lithostratigraphic framework. Lithologically, the Andalhuala Formation in SMV is broadly characterized by sandstones and conglomerates poorly sorted, polymict and matrix-supported clasts, with scarce participation of pelites (Georgieff 1998). In both areas, SMV and VQB, this unit is composed of facies of brownish, reddish, and greyish sandstones with tabular, lenticular, trough cross-stratification, ripple marks, and cuneiform cross-stratification, often interbedded with tabular massive siltstones and several tuff beds. Moreover, the Andalhuala Formation shows several secondary features that evidence the subaerial exposure and water table fluctuations, which agree with the inferred permanent fluvial subenvironment passing to an eolian system with dunes (Bonini et al. 2017, 2021).
Although the literature mentions the same stratigraphic formations in VQB and SMV, it should be noted that the units that form the Santa María Group sometimes show important diachronies between those cropping out in both basins (see Spagnuolo et al. 2010, 2013, 2015; Georgieff et al. 2012a, b, 2017; Georgieff and Díaz 2014; Bonini 2014; Bonini et al. 2017, 2021). In general, the inferred palaeoenvironments are shallow lacustrine (but also continental sabkha in SMV; Ibañez, 2001; Esteban et al. 2019) and sandy-gravel braided fluvial for the Chiquimil and Andalhuala formations at both sites, but the dating of the tuffaceous strata reveals that their deposition were older in VQB. A clear example is the Chiquimil Formation (see Fig. 1), which presents an age of 7.14 Ma for its top at East of PCQ, while in the SMV an age of ca. 6.88 was obtained from the top of the underlying unit, Las Arcas Formation (Georgieff et al. 2014; 2017); this shows that the deposition of the Chiquimil Formation at SMV was younger, and therefore the lithostratigraphic correlation between both areas cannot be established by that criteria. Likewise, the determination of the ages of the specimens analyzed in the present work has been carried out taking into account the absolute ages (geochronology) and not the formation (lithostratigraphy) from which they originate.
Systematic Paleontology
Superorder Xenarthra Cope, 1889
Order Cingulata Illiger, 1811
Family Glyptodontidae Gray, 1869
Tribe Plohophorini Castellanos, 1932 (nom. transl. Hoffstetter, 1958)
Genus Stromaphorus Castellanos, 1925
(= Phlyctaenopyga Cabrera, 1944 new synonymy)
Species: Stromaphorus ameghini (Ameghino, 1889; ex Moreno, 1882)
Other species
Stromaphorus trouessarti (Moreno, 1888) nov. comb.
Stromaphorus ameghini (Ameghino, 1889; ex Moreno, 1882)
= Hoplophorus ameghinii Moreno, 1882, p. 120 [nom. nud.]; Plohophorus ameghini Ameghino, 1889, p. 825, plates LXIX, Figs. 19 and 20 and LXXXII, Figs. 5 and 6; Neuryurus compressidens Moreno and Mercerat, 1891, p. 224; Plohophorus philippii Moreno and Mercerat, 1891, p. 225; Plohophorus ameghinii Ameghino, 1902, p. 2; Plohophorus ameghinoi Ameghino, 1904, p. 288; Stromaphorus ameghinoi (Ameghino, 1904) Castellanos, 1925, p. 96 (not 1940, p. 27) [n. comb.]; Stromaphorus philippii (Moreno and Mercerat, 1891), Cabrera 1939 [n. comb.]; Stromaphorus ameghinoi (Ameghino, 1904) Castellanos, 1940, p. 27 (not 1925, p. 96); Urotherium compressidens Castellanos 1940, p. 273; Stromaphorus compressidens (Moreno and Mercerat, 1891), Cabrera 1944, p. 30 [n. comb.]. Phlyctaenopyga ameghini (Ameghino, 1889), Cabrera 1944, p. 42 [n. gen, n. comb.].
Holotype
MLP-PV 16–101, small fragment of carapace and some isolated osteoderms. Santa María Department, Catamarca Province, Argentina.
Geographic and Stratigraphic Occurrence: Catamarca Province: Santa María Valley, Puerta de Corral Quemado, Corral Quemado and San Fernando; Chiquimil Formation, Andalhuala Formation and Corral Quemado Formation, Late Miocene-Pliocene (Cabrera 1944; Marshall and Patterson 1981; Bonini 2014; Zamorano et al. 2011). Tucumán Province: Tiopunco (Cabrera 1944; Zamorano et al. 2011). La Rioja Province: El Degolladito; Salicas Formation, Late Miocene (Brandoni and González-Ruiz 2020). Córdoba Province: Arroyo Los Chiflones, Villa Cura Brochero; Brochero Formation, Miocene-Pliocene (Cruz 2011, 2013).
Materials analysed in this work, geographic and stratigraphic provenance and age: FMNH-P14396, deformed skull, Ampajango, Catamarca Province, Argentina; Chiquimil Formation, Stratigraphic level XI from Stahlecker in Marshall and Patterson (1981, Appendix II) between 6.88 to 6.02 Ma, Messinian (Late Miocene); FMNH-P14414, incomplete and deformed skull, dorsal carapace fragment, femur, two caudal rings, distal portion of caudal tube, Puerta de Corral Quemado, Belén Department, Catamarca Province, Argentina; Andalhuala Formation, Stratigraphic level 17 from Marshall and Patterson (1981), age ca. 6.9 to 6.3Ma, Messinian (Late Miocene); FMNH-P14439, complete carapace, Puerta de Corral Quemado, Belén Department, Catamarca Province, Argentina; Andalhuala Formation, Stratigraphic level 26 from Marshall y Patterson (1981); age ca. 4.9 to 4.4 Ma, Zanclean (Early Pliocene); FMNH-P14532, proximal portion of caudal tube, Puerta de Corral Quemado, Belén Department, Catamarca Province, Argentina; Andalhuala Formation/Corral Quemado Formation, Stratigraphic levels 15–32 from Marshall and Patterson 1981; age ca. 7.14 to 3.66 Ma, Miocene-Pliocene; FMNH-P15771, small fragments of carapace, some from the anterior region and some from the posterior region, Tio Punco, Tafi, Tucumán Province, Argentina; unknown stratigraphic level, Pliocene, [originally classified as Glyptodontidae indet. in Marshall and Patterson 1981]; MCH-P39, small fragment of carapace, San Fernando Norte, Belén Department, Catamarca Province, Argentina; Andalhuala Formation, immediately above the tuff dated in ca. 4.72 Ma, Zanclean (Early Pliocene); MCH-P174, isolated osteoderm, San Fernando Norte, Belén Department, Catamarca Province, Argentina; Andalhuala Formation, immediately above the tuff dated in ca. 4.72 Ma, Zanclean (Early Pliocene). New studied specimen; MCH-P176, isolated osteoderm, San Fernando Norte, Belén Department, Catamarca Province, Argentina; Andalhuala Formation, immediately above the tuff dated in ca. 4.72 Ma, Zanclean stage, Pliocene. New studied specimen; MCH-P177, isolated osteoderm, San Fernando Norte, Belén Department, Catamarca Province, Argentina; Andalhuala Formation, immediately above the tuff dated in ca. 4.72 Ma., Zanclean (Early Pliocene). New studied specimen; MCH-P247, isolated osteoderm, San Fernando Norte, Belén Department, Catamarca Province, Argentina; Andalhuala Formation, age ca. 4.72 to 4.79 Ma, Zanclean (Early Pliocene). New studied specimen; MCH-P323, isolated osteoderm, Faldeo Occidental Cerro Pampa (San Fernando Sur), Belén Department, Catamarca Province, Argentina; Andalhuala Formation, immediately below the tuff dated in 5.59 Ma, Messinian (Late Miocene). New studied specimen; MCH-P326, isolated osteoderms, San Fernando Norte, Belén Department, Catamarca Province, Argentina; Andalhuala Formation, age ca. 3.6 to 4.72 Ma, Zanclean (Early Pliocene). New studied specimen; MCH-P328, isolated osteoderms, fragments of carapace, fragments of caudal rings and fragments of caudal tube, San Fernando Norte, Belén Department, Catamarca Province, Argentina; Andalhuala Formation, age ca. 3.6 to 4.72 Ma, Zanclean (Early Pliocene). New studied specimen; MCH-P364, isolated osteoderm, Western Slopes of Cerro Pampa. Chiquimil Formation, age more than 7.14 Ma; Messinian-Tortonian (Late Miocene). New studied specimen; MCH-P365, 21 isolated osteoderms, Western Slopes of Cerro Pampa, Belén Department, Catamarca Province, Argentina; Andalhuala Formation, above tuff dated in 5.59 Ma, Miocene-Pliocene. New studied specimen; MLP-PV 16–138, incomplete and deformed left horizontal ramus, holotype of “Stromaphorus compressidens” (Neuryurus compressidens Moreno and Mercerat, 1891), Bajo de Andalhualá, Santa María Department, Catamarca Province, Argentina; Corral Quemado Formation; MLP-PV 29-X-8-1, laterally deformed skull, mandible and carapace fragments; referred to “Stromaphorus compressidens” by Cabrera (1944). Barranca del Palito Parado, campo del Jarillar, Puerta de Corral Quemado, Belén Department, Catamarca Province, Argentina; “Araucaniano”; MLP-PV 29-X-8-9, caudal tube; referred to “Stromaphorus compressidens” by Cabrera (1944). Campo de los Cálibas, Puerta de Corral Quemado, Belén Department, Catamarca Province, Argentina; “Araucaniano”; MLP-PV 29-X-10-1, incomplete skull, cephalic shield, carapace fragments, parts of the sacral and first caudal vertebrae, caudal tube and parts of the caudal rings; referred to “Phlyctaenopyga” ameghini by Cabrera (1944). Loma de la Greda, San Fernando, Belén Department, Catamarca Province, Argentina; “Araucaniano”; MLP-PV 29-X-10-2, carapace deformed by pressure, parts of the first caudal ring, tube and pelvis; referred to “Phlyctaenopyga” ameghini by Cabrera (1944). Loma de la Greda, San Fernando, Belén Department, Catamarca Province, Argentina; “Araucaniano”. See Online Resource 2 for a complete list of materials historically referring to “Phlyctaenopyga” ameghini (Ameghino, 1889) and “Stromaphorus compressidens” (Moreno and Mercerat, 1891), and it is reassignment to Stromaphorus ameghini (Ameghino, 1889; ex Moreno, 1882).
Emended diagnosis: Medium sized glyptodont (see Online Resource 3), larger than Pseudoplohophorus but smaller than the Pleistocene genera Panochthus, Glyptodon, and Doedicurus. Lateral skull profile similar to Plohophorus and Pseudoplohophorus. Nasal region dorsoventrally reduced; nasofrontal area inclined 152º anteroventrally in front of the orbital notches; subelliptical orbital notch, with the main axis inclined 110° counterclockwise to the dorsoventral axis; inverted subtrapezoidal nasal aperture with both lateral margins convex; subtriangular rostral area in front of the orbital notches; without postorbital bar; zygomatic arches more elongated anteroposteriorly than those of other Plohophorini (eg., Plohophorus figuratus); palate general morphology straight, as in Plohophorus and different from Pseudoplohophorus; Mf1 and Mf2 with triangular morphology, Mf4-8 with very marked trilobulation, Mf4 coincides with the infraorbital foramen. The dorsal carapace is sub-rectangular with variation in the ornamentation depending on the sector. Anterior portion: rounded and flat central figure, surrounded by a single row of 10–12 small rounded peripheral figures. Middle portion: subcircular and slightly convex central figure, surrounded by a first row of 11 to 15 peripheral figures and a second row which is always incomplete; it differs clearly from Nopachtus, Panochthus and Propanochthus in which the second row is always complete. Postero-dorsal region (pelvic region): round and very convex central figure, surrounded by a first row of 12–21 peripheral figures and a second one, complete, between 21–27; this is the only area of the carapace in which the second row of peripheral figures is complete. Caudal margin with large convex central figures preceded anteriorly by 3–5 rows of peripheral figures, one row on the sides of the central figure and a free border on the posterior margin. In dorsal and ventral view, the caudal tube has parallel lateral borders along its entire length instead of tapering distally, as the caudal tubes of some genera (e.g. Pseudoplohophorus and Plohophorus) and almost circular in transverse outline. Simple rosette pattern, with a smooth-surfaced central figure surrounded by a single complete row of shared peripheral figures. At the apex there are two large smooth terminal figures (T) which, in the more distal portion, are in contact. It has four lateral figures (numbered I, II, III and IV, see Fig. 7) that reduce in size towards the proximal portion. Figure I is characteristically convex, unlike figures II, III and IV, which are flatter. Between the lateral and marginal figures there is a row of small peripheral figures.