Virtual reconstruction of cranial endocasts of traversodontid cynodonts (Eucynodontia: Gomphodontia) from the upper Triassic of Southern Brazil.

The brain endocasts of the late Triassic (Carnian) traversodontids (Eucynodontia: Gomphodontia) Siriusgnathus niemeyerorum and Exaeretodon riograndensis from southern Brazil are described based on virtual models generated using computed tomography scan data. Their skull anatomy resembles that of other non-mammaliaform cynodonts, showing an endocranial cavity that is not fully ossified. A "V-shaped" orbitosphenoid, neither fully developed nor ossified is present in E. riograndensis. The nasal cavity is confluent with the encephalic cavity. Thus, the anterior limit of the olfactory bulbs is not definite. The brain endocast is elongated, being narrow anteriorly and wide posteriorly, with the maximum width at the parafloccular cast. The olfactory bulbs do not present a clear division between their counterparts, due to the absence of a longitudinal sulcus. A longitudinal sulcus in the forebrain delimiting the cerebral hemispheres, the pineal tube, and the parietal foramen are absent in both taxa. The large and well-developed unossified zone is partially separated from the remaining endocast by a notch formed by the supraoccipital. The encephalization quotients, as well as the endocranial volume/body mass relationships of S. niemeyerorum and E. riograndensis are within the range expected for non-mammaliaform Therapsida.

Two New Cynodonts (Therapsida) from the Middle-Early Late Triassic of Brazil and Comments on South American Probainognathians.

We describe two new cynodonts from the early Late Triassic of southern Brazil. One taxon, Bonacynodon schultzi gen. et sp. nov., comes from the lower Carnian Dinodontosaurus AZ, being correlated with the faunal association at the upper half of the lower member of the Chañares Formation (Ischigualasto-Villa Unión Basin, Argentina). Phylogenetically, Bonacynodon is a closer relative to Probainognathus jenseni than to any other probainognathian, bearing conspicuous canines with a denticulate distal margin. The other new taxon is Santacruzgnathus abdalai gen. et sp. nov. from the Carnian Santacruzodon AZ. Although based exclusively on a partial lower jaw, it represents a probainognathian close to Prozostrodon from the Hyperodapedon AZ and to Brasilodon, Brasilitherium and Botucaraitherium from the Riograndia AZ. The two new cynodonts and the phylogenetic hypothesis presented herein indicate the degree to which our knowledge on probainognathian cynodonts is incomplete and also the relevance of the South American fossil record for understanding their evolutionary significance. The taxonomic diversity and abundance of probainognathians from Brazil and Argentina will form the basis of deep and complex studies to address the evolutionary transformations of cynodonts leading to mammals.

Comportamento reprodutivo de Melanotênia Boesemani e fecundidade em três faixas de tamanho / Reproductive behavior of Boeseman's rainbowfish and fecundity in three size ranges

Registrou-se o comportamento reprodutivo e se comparou a fertilidade e fecundidade de 16 casais demelanotênia boesemani (Melanotaenia boesemani Allen e Cross, 1980), com tamanhos entre 1,437 g e 4,484 g, afim de elucidar características reprodutivas dessa espécie que é valorizada no comércio de peixes ornamentais.Observou-se que o comportamento de corte e acasalamento é idêntico para todos os tamanhos e similar ao deoutras espécies do grupo das melanotênias. Através de análise multivariada percebeu-se distribuição de trêsfaixas de tamanho – 48,7 mm (1,579 g; n = 6), 57,2 mm (2,619 g; n=8) e 65,8 (4,484 g; n=1) – com resultadosdistintos para características reprodutivas. Sendo as fêmeas de tamanho mediano (57,2 mm) as que apresentarammelhor rendimento reprodutivo com média total de 1.046 ovos, em 32 dias, sendo 691 a média de ovosfecundados e viáveis (66,1%).

It was registered the reproductive behavior of Boeseman's rainbowfish (Melanotaenia boesemani Allenand Cross, 1980), comparing fecundity and fertility of individuals weghing between 1.437 g and 4.484 g, aimingat understand the reproductive characteristics of this high-value species among the ornamental fish commerce.It was observed that courtship and breeding behavior are identical for all the evaluated sizes and similar forthose from the rainbowfish group. Through the multivariated analysis, it was noted the distribution of three sizeranges – 48.7 mm (1.579 g; n = 6), 57.2 mm (2.619 g; n=8) and 65.8 (4.484 g; n=1) – with different results forreproductive characteristics. Females with medium size (57.2 mm) presented the best reproductive yield, withtotal average of 1,046 eggs within 32 days, being 691 the average of fecundated and viable eggs (66.1%).

Comportamento reprodutivo de Melanotênia Boesemani e fecundidade em três faixas de tamanho / Reproductive behavior of Boeseman's rainbowfish and fecundity in three size ranges

Registrou-se o comportamento reprodutivo e se comparou a fertilidade e fecundidade de 16 casais demelanotênia boesemani (Melanotaenia boesemani Allen e Cross, 1980), com tamanhos entre 1,437 g e 4,484 g, afim de elucidar características reprodutivas dessa espécie que é valorizada no comércio de peixes ornamentais.Observou-se que o comportamento de corte e acasalamento é idêntico para todos os tamanhos e similar ao deoutras espécies do grupo das melanotênias. Através de análise multivariada percebeu-se distribuição de trêsfaixas de tamanho 48,7 mm (1,579 g; n = 6), 57,2 mm (2,619 g; n=8) e 65,8 (4,484 g; n=1) com resultadosdistintos para características reprodutivas. Sendo as fêmeas de tamanho mediano (57,2 mm) as que apresentarammelhor rendimento reprodutivo com média total de 1.046 ovos, em 32 dias, sendo 691 a média de ovosfecundados e viáveis (66,1%).(AU)

It was registered the reproductive behavior of Boeseman's rainbowfish (Melanotaenia boesemani Allenand Cross, 1980), comparing fecundity and fertility of individuals weghing between 1.437 g and 4.484 g, aimingat understand the reproductive characteristics of this high-value species among the ornamental fish commerce.It was observed that courtship and breeding behavior are identical for all the evaluated sizes and similar forthose from the rainbowfish group. Through the multivariated analysis, it was noted the distribution of three sizeranges 48.7 mm (1.579 g; n = 6), 57.2 mm (2.619 g; n=8) and 65.8 (4.484 g; n=1) with different results forreproductive characteristics. Females with medium size (57.2 mm) presented the best reproductive yield, withtotal average of 1,046 eggs within 32 days, being 691 the average of fecundated and viable eggs (66.1%).(AU)

A new aetosaur from the Upper Triassic of the Santa Maria Formation, southern Brazil.

Aetosaurs are armored pseudosuchian archosaurs widespread in Upper Triassic units. In South America, four taxa were previously recorded: Aetosauroides scagliai, Neoaetosauroides engaeus, Aetobarbakinoides brasiliensis, and Chilenosuchus forttae. Herein we describe a new Late Triassic juvenile aetosaur from the Santa Maria Formation of southern Brazil, Polesinesuchus aurelioi gen. et sp. nov., increasing the paleobiodiversity of this interesting group to five taxa in Western Gondwana. The holotype is composed of cranial (parietal and braincase) and postcranial elements (cervical, dorsal, sacral, caudal vertebrae, both scapulae, a humerus, ilium, pubis, ischium, tibia, a partial right pes, and anterior and mid-dorsal paramedian osteoderms). It belongs to a juvenile individual, as its neurocentral sutures are open in all vertebrae, and also due to its small size. However, future paleohistological investigation is necessary to fully corroborate this assumption. This new taxon is distinguished from all other aetosaurs by the presence of an unique combination of character states (not controlled by ontogeny) such as: cervical vertebrae with prezygapophyses widely extending laterally through most of the anterior edge of the diapophyses; absence of hyposphene articulations in both cervical and mid-dorsal vertebrae; presence of a ventral keel in cervical vertebrae; anterior and mid-dorsal vertebrae without a lateral fossa in their centra; expanded proximal end of scapula; anteroposteriorly expanded medial portion of scapular blade; a short humerus with a robust shaft; and a dorsoventral and very low iliac blade with a long anterior process which slightly exceeds the pubic peduncle. Regarding its phylogenetic relationships, the present analysis placed Polesinesuchus as the sister taxon of Aetobarbakinoides and both as sister taxa of the unnamed monophyletic clade Desmatosuchinae plus Typothoracisinae. 

Ecophysiological responses to the effect of annual management on an endemic viviparous fish in central plateau of México

Studies on the biological aspects of fish typically focus on species that currently have commercial value, causing species that lack such market value to be ignored. This is the case of several freshwater fish, specifically of several members of the Goodeidae family. In the State of Querétaro there are several species of this family characterized for being viviparous and having distinctive sexual dimorphism that may have commercial potential. The subject of this study is Girardinichthys multiradiatus, a viviparous fish endemic to the upper-half of the Lerma River basin. The lack of knowledge regarding its biology and ecology has prevented the development of guidelines to manage its habitat and to preserve its population. The objective was to determine the ecophysiological responses of G. multiradiatus to its environmental management. From the sampling (24 hours every two months) population structure and dynamics were analyzed throughout a hydrological cycle using meristic data (standard length). Trophic and ecophysiological responses to fluctuations in environmental factors were also identified. Although the mexcalpique is a polytrophic species, results show that it prefers feeding on Diptera or Cladocera, while detritus is the third substance frequently found in their stomachs. Environmentally, the water regime is responsible for fluctuations in the population dynamics of the species, while temperature changes are the most influence its energy balance. These results can guide efforts to conserve this species and its habitat.(AU)

Los estudios sobre aspectos biológicos de los peces se centran, generalmente, en especies que actualmente tienen interés comercial, lo que ocasiona que las especies que carecen de tal valor en el mercado estén prácticamente olvidadas; tal es el caso de varios peces de agua dulce y más específicamente de algunos integrantes de la familia Godeidae. En el estado de Querétaro se encuentran varias especies pertenecientes a esta familia que se caracterizan por ser vivíparas y presentar un marcado dimorfismo sexual, aspectos que pudieran definir un potencial comercial. El pez objeto de este estudio es Girardinichthys multiradiatus, especie endémica de la parte alta-media de la cuenca del río Lerma; los lugares donde habita presentan procesos de degradación, fragmentación del hábitat y extracción de agua, que ponen en riesgo su existencia. Además, la falta de conocimiento sobre su biología y ecología, no permiten que se elaboren pautas de gestión de sus poblaciones o hábitats con fines de conservación y preservación de la especie o de los procesos ecológicos que mantienen la estabilidad del ecosistema que ocupa. En el presente trabajo se estudió la población de G. multiradiatus localizada en el bordo de San Martín, Amealco. El objetivo del presente trabajo fue determinar las respuestas ecofisológicas de G. multiradiatus debido al manejo de su ambiente. Se hicieron ciclos de 24 horas en muestreos bimensuales a lo largo de un ciclo hidrológico en el que se analizaron la estructura y dinámica de la población; asimismo, se determinaron las respuestas tróficas y ecofisiológicas de la población ante las fluctuaciones de los factores ambientales de su entorno. Los resultados muestran que aunque el mexcalpique es polítrofo, prefiere dípteros, cladóceros y detritus, habiendo diferencias alimentarias entre las clases de edades. G. multiradiatus presenta 12 clases de talla que van de 8 a 48 mm de longitud patrón. En el medio ambiente, el régimen de agua es responsable de las fluctuaciones en la dinámica poblacional de las especies, mientras que el cambio de temperatura es el factor de mayor influencia sobre su balance energético. Estos resultados pueden guiar los esfuerzos para conservar esta especie y su hábitat.(AU)

Ecophysiological responses to the effect of annual management on an endemic viviparous fish in central plateau of México

Studies on the biological aspects of fish typically focus on species that currently have commercial value, causing species that lack such market value to be ignored. This is the case of several freshwater fish, specifically of several members of the Goodeidae family. In the State of Querétaro there are several species of this family characterized for being viviparous and having distinctive sexual dimorphism that may have commercial potential. The subject of this study is Girardinichthys multiradiatus, a viviparous fish endemic to the upper-half of the Lerma River basin. The lack of knowledge regarding its biology and ecology has prevented the development of guidelines to manage its habitat and to preserve its population. The objective was to determine the ecophysiological responses of G. multiradiatus to its environmental management. From the sampling (24 hours every two months) population structure and dynamics were analyzed throughout a hydrological cycle using meristic data (standard length). Trophic and ecophysiological responses to fluctuations in environmental factors were also identified. Although the mexcalpique is a polytrophic species, results show that it prefers feeding on Diptera or Cladocera, while detritus is the third substance frequently found in their stomachs. Environmentally, the water regime is responsible for fluctuations in the population dynamics of the species, while temperature changes are the most influence its energy balance. These results can guide efforts to conserve this species and its habitat.

Los estudios sobre aspectos biológicos de los peces se centran, generalmente, en especies que actualmente tienen interés comercial, lo que ocasiona que las especies que carecen de tal valor en el mercado estén prácticamente olvidadas; tal es el caso de varios peces de agua dulce y más específicamente de algunos integrantes de la familia Godeidae. En el estado de Querétaro se encuentran varias especies pertenecientes a esta familia que se caracterizan por ser vivíparas y presentar un marcado dimorfismo sexual, aspectos que pudieran definir un potencial comercial. El pez objeto de este estudio es Girardinichthys multiradiatus, especie endémica de la parte alta-media de la cuenca del río Lerma; los lugares donde habita presentan procesos de degradación, fragmentación del hábitat y extracción de agua, que ponen en riesgo su existencia. Además, la falta de conocimiento sobre su biología y ecología, no permiten que se elaboren pautas de gestión de sus poblaciones o hábitats con fines de conservación y preservación de la especie o de los procesos ecológicos que mantienen la estabilidad del ecosistema que ocupa. En el presente trabajo se estudió la población de G. multiradiatus localizada en el bordo de San Martín, Amealco. El objetivo del presente trabajo fue determinar las respuestas ecofisológicas de G. multiradiatus debido al manejo de su ambiente. Se hicieron ciclos de 24 horas en muestreos bimensuales a lo largo de un ciclo hidrológico en el que se analizaron la estructura y dinámica de la población; asimismo, se determinaron las respuestas tróficas y ecofisiológicas de la población ante las fluctuaciones de los factores ambientales de su entorno. Los resultados muestran que aunque el mexcalpique es polítrofo, prefiere dípteros, cladóceros y detritus, habiendo diferencias alimentarias entre las clases de edades. G. multiradiatus presenta 12 clases de talla que van de 8 a 48 mm de longitud patrón. En el medio ambiente, el régimen de agua es responsable de las fluctuaciones en la dinámica poblacional de las especies, mientras que el cambio de temperatura es el factor de mayor influencia sobre su balance energético. Estos resultados pueden guiar los esfuerzos para conservar esta especie y su hábitat.

Taxonomic reappraisal of the sphagesaurid crocodyliform Sphagesaurus montealtensis from the Late Cretaceous Adamantina Formation of São Paulo State, Brazil.

Sphagesaurus montealtensis is a sphagesaurid whose original description was based on a comparison with Sphagesaurus huenei, the only species of the clade described to that date. Better preparation of the holotype and the discovery of a new specimen have allowed the review of some characteristics and the identification of several synapomorphies of S. montealtensis with the genus Caipirasuchus: presence of antorbital fenestra; external nares bordered only by the premaxillae; premaxilla with four teeth and one diastema (between the 3rd-4th teeth); one diastema between the 4th premaxillary tooth and the 1" maxillary tooth; dentary with ten teeth and two diastemata (between the 4th-5th and 5th-6th teeth); nasal with a groove parallel to the suture with the frontal bone; nasal long, with an acute anterior margin touching anterolaterally the premaxilla, jugal is a straight bar in the lateral view; frontal is longer than wide; a dorsoventrally expanded and vertically oriented quadrate with a groove separating the medial and lateral condyles; the frontal has a discrete sagittal crest; dentary with six posterior sphagesauriform teeth and four anterior conical teeth, the first three are the smallest of the series and the fourth is slightly laterally compressed. The referral of S. montealtensis to the genus Caipirasuchus, as Caipirasuchus montealtensis comb. nov. is proposed here, based on the new taxonomic observations and the results of a phylogenetic analysis.

Nota sobre la dieta de Ameiva edracantha (Squamata, Teiidae) en el Parque Nacional Cerros de Amotape, Tumbes, Perú / Note on the diet of Ameiva edracantha (Squamata, Teiidae) in Cerros de Amotape National Park, Tumbes, Peru

The diet of Ameiva edracantha Bocourt 1874, a terrestrial diurnal teiid lizard distributed in northwestern Peru and southwestern Ecuador is described for the first time. Stomach contents of fifteen individuals collected from quebrada La Angostura were analyzed. Lepidopteran larvae, coleopterans, orthopterans and spiders were the dominant preys in the lizard’s diet. Snout-vent length and head length, width and height were not correlated to prey length, width and volume. Other parameters such as profitability and prey target selection could be involved in prey selection by A. edracantha.

Se describe por primera vez la dieta de Ameiva edracantha, una especie de lagartija teiida diurna terrestre que se distribuye en la costa noroeste de Perú y suroeste de Ecuador. Se analizó el contenido estomacal de 15 individuos colectados en la quebrada La Angostura. La dieta de A. edracantha estuvo compuesto principalmente por larvas de lepidópteros, coleópteros, ortópteros y arañas. La longitud hocico-cloaca y la longitud, ancho y alto de la cabeza no se relacionó con la longitud, ancho y volumen de las presas. Otros parámetros como selección específica de presas y profitabilidad, podrían estar involucrados en la selección de presas en A. edracantha.