Bone Anatomy of the Thoracic Limb in the Common Hippopotamus (Hippopotamus amphibius) and White Rhinoceros (Ceratotherium simum)

SUMMARY: Although megaherbivores do not belong to the Brazilian fauna, they can be found in national zoos, which makes it important to know the anatomy of the locomotor apparatus to contribute to the clinical routine of zoos and veterinary rehabilitation centers. Thus, the aim of this study was to describe the anatomical structures of the thoracic limb bones in the common hippopotamus (Hippopotamus amphibius) and white rhinoceros (Ceratotherium simum) and to compare them with the bone structures described for other ungulates. The scapula had a triangular appearance in the common hippopotamus, whereas in the white rhinoceros it had a rectangular appearance. The acromion was observed only in the common hippopotamus scapula. The hippopotamus humerus did not have the intermediate tubercle, only the greater and lesser tubercles, unlike the rhinoceros which also has the intermediate tubercle. The two megamammals studied had an ulna not incorporated to the radius and seven carpal bones distributed in two bone rows. The common hippopotamus had four digits and four metacarpal bones, while the white rhino had three digits, hence three metacarpal bones. Although with some species-specific differences, the bone anatomy found in the studied megaherbivores was similar to that described for domestic ungulates, such as horses and cattle. The fact that the bones studied belong to articulated skeletons of the collection of the Museum of Anatomy made it difficult to identify some anatomical structures. This study can help veterinarians in bone health care, animal welfare and comfort of such species present in Brazilian zoological parks.

Aunque los megaherbívoros no pertenecen a la fauna brasileña, se pueden encontrar en zoológicos nacionales, lo que hace importante conocer la anatomía del aparato locomotor para contribuir a la rutina clínica de los zoológicos y de los centros de rehabilitación veterinaria. Por tanto, el objetivo de este estudio fue describir las estructuras anatómicas de los huesos de los miembros torácicos en el hipopótamo común (Hippopotamus amphibius) y el rinoceronte blanco (Ceratotherium simum) y compararlas con las estructuras óseas descritas para otros ungulados. La escápula tenía una apariencia triangular en el hipopótamo común, mientras que en el rinoceronte blanco tenía una apariencia rectangular. El acromion se observó sólo en la escápula del hipopótamo común. El húmero del hipopótamo no tenía el tubérculo intermedio, sólo los tubérculos mayor y menor, a diferencia del rinoceronte que también tiene el tubérculo intermedio. Los dos ejemplares de megamamíferos estudiados tenían una ulna no incorporada al radio y siete huesos del carpo distribuidos en dos filas óseas. En el hipopótamo común se observaron cuatro dedos y cuatro huesos metacarpianos, mientras que en el rinoceronte blanco se encontraron tres dedos, por lo tanto, tres huesos metacarpianos.A pesar de algunas diferencias específicas de cada especie, la anatomía ósea encontrada en los megaherbívoros estudiados fue similar a la descrita para los ungulados domésticos, tal como los caballos y el ganado. El hecho de que los huesos estudiados pertenezcan a esqueletos articulados de la colección del Museo de Anatomía dificultó la identificación de algunas estructuras anatómicas. Este estudio puede ayudar a los veterinarios en el cuidado de la salud ósea, el bienestar animal y el confort de las especies presentes en los parques zoológicos brasileños.

Protocolo de osteotecnia aplicado a manos humanas

R E S U M E N El estudio del componente osteoarticular de la mano humana, requiere de estrategias didácticas que le permitan al estudiante comprender sus relaciones y accidentes óseos. La osteotecnia, permite obtener modelos óseos y facilita el proceso de aprendizaje del estudiante al tener un acercamiento real con las piezas. El objetivo fue presentar un protocolo de osteotecnia aplicado a manos humanas. Este trabajo se realizó en el laboratorio de anatomía del Departamento de Morfología de la Universidad del Valle en Cali - Colombia; se utilizaron cuatro manos humanas entregadas en custodia por el Instituto Nacional de medicina legal y ciencias forenses. El protocolo se desarrolló en dos fases; fase I, manejo de tejidos blandos y fase II, manejo de tejido óseo. Se obtuvieron cuatro modelos anatómicos del componente óseo de la mano: dos articulados y dos desarticulados para uso académico. Con la aplicación del protocolo no solo se obtuvo modelos anatómicos óseos de larga durabilidad que benefician a los estudiantes y al docente en las clases teórico-prácticas; si no, el estudiante ejecutor que profundizó en el conocimiento de este segmento corporal durante y después del desarrollo de la técnica.

The study of the osteoarticular component of the human hand requires didactic strategies which enable the student to understand its osseous relationships and related accidents. Osteotechnics, permits the use of bone models, and facilitate a student's learning process by having access to real pieces. The objective was to present an osteotechnical protocol applied to human hands This study was carried out in the anatomy laboratory of the Morphology Department of the Universidad del Valle in Cali, Colombia, four human hands handed over to the custody of the National Institute of Legal Medicine and Forensic Sciences were used the protocol was developed in two phases: Phase I: handling of soft tissues; Phase II: handling of bone tissue. Of the four anatomical models of the bone component of the hand obtained, two were articulated and two disarticulated for academic use. With the application of the protocol, not only were anatomical bone models of long durability obtained, benefitting both student and teacher in the theoretical-practical classes, but also, the student who carried out the procedure deepened their knowledge of this anatomical segment during and after the development of the technique.

O estudo do componente osteoarticular da mão humana requer, estratégias didáticas que permitem ao aluno compreender suas relações e acidentes ósseos. Osteotecnia, permite obter modelos ósseos e facilita o processo de aprendizagem do aluno, tendo uma aproximação real com o peças. O objetivo foi apresentar um protocolo osteotécnico aplicado em mãos humanas. Este trabalho foi realizado no laboratório de anatomia do Departamento de Morfologia da Universidad del Valle em Cali - Colômbia. Foram utilizadas quatro mãos humanas disponibilizadas ao Instituto Nacional de Medicina Legal e Ciências Forenses. O protocolo foi desenvolvido em duas fases. Fase I, gerenciamento de tecidos moles. Fase II, gerenciamento de tecido ósseo. Quatro modelos anatômicos do componente ósseo do mão foram obtidos: dois articuladas e dois desarticulados para uso acadêmico. Com a aplicação do protocolo, não só foram obtidos modelos ósseos anatômicos de longa duração que beneficiam aos alunos e ao professor nas aulas teórico-práticas, mas também ao aluno executor que aprofundou no conhecimento deste segmento durante e após o desenvolvimento da técnica.

Estimation of Stature Based on Metatarsal Bones in a Thai Population / Estimación de la Estatura Basada en los Huesos Metatarsianos en una Población Tailandesa

SUMMARY: Stature estimation is one of the essential procedures for personal identification in forensic osteology. Therefore, the purposes of this study are to analyze the correlation between length and width of metatarsal measurements and stature, and to develop the regression equations for a Thai population. In this study, the samples were divided into two groups. The first group was called the "training group" for generating stature estimation equations, comprised of 200 skeletons, aged between 19-94 years. The second group was called the "test group" for evaluating the accuracy of generated equations, comprising 40 skeletons. The correlation between metatarsal parameters and stature were moderate to high, and all variables had positive significant correlation with stature. For males, the left ML2 is the length variable that showed the most correlation degree against stature (r=0.702), and the left MSW4 is the width variable that had the most correlation degree against stature (r=0.483). For females, right ML1 is the length variable that had the most correlation degree against stature (r=0.632), and right PW3 is the width stature that had the most correlation degree against stature (r=0.481). For all samples, left ML1 was the length variable that had the most correlation degree against stature (r=0.796) and right PW3 was the width variable that had the most correlation degree against stature (r=0.712). The results of generating multiple regression equations using a stepwise method reveals that the correlation coefficient (R) and standard error of estimate (SEE) were 0.761 and 4.96 cm, respectively, for males, and 0.752 and 4.93 cm for females, with 0.841 and 5.26 cm for all samples, respectively. According to these results, the mean of absolute error from the test group ranged from 3 to 5 cm. Therefore, stature estimation equations using length and width of metatarsals from our study can be applied to estimate stature in the Thai population.

La estimación de la estatura es uno de los procedimientos esenciales para la identificación personal en osteología forense. Por lo tanto, los propósitos de este estudio fueron analizar la correlación entre la longitud y el ancho de las medidas metatarsianas y la estatura, y desarrollar las ecuaciones de regresión para una población tailandesa. Las muestras se dividieron en dos grupos. El primer grupo se denominó "grupo de entrenamiento" para generar ecuaciones de estimación de estatura, compuesto por 200 esqueletos, con edades comprendidas entre los 19 y los 94 años. El segundo grupo se denominó "grupo de prueba" para evaluar la precisión de las ecuaciones generadas, que comprende 40 esqueletos. La correlación entre los parámetros metatarsianos y la estatura fue de moderada a alta, y todas las variables tuvieron una correlación significativa positiva con la estatura. Para el sexo masculino, la variable longitud ML2 izquierda es la que mayor grado de correlación presentó con la estatura (r=0,702), y la izquierda MSW4 fue la variable ancho la que mayor grado de correlación presentó con la estatura (r=0,483). Para el sexo femenino, ML1 derecho fue la variable longitud que tuvo mayor grado de correlación con la estatura (r=0,632), y PW3 derecha fue la variable ancho estatura que tuvo mayor grado de correlación con la estatura (r=0,481). Para todas las muestras, ML1 izquierdo fue la variable longitud que tuvo mayor grado de correlación con la estatura (r=0,796) y PW3 derecha fue la variable ancho que tuvo mayor grado de correlación con la estatura (r=0,712). Los resultados de generar ecuaciones de regresión múltiple usando un método paso a paso revela que el coeficiente de correlación (R) y el error estándar de estimación (SEE) fueron 0,761 y 4,96 cm, respectivamente, para los hombres y 0,752 y 4,93 cm para las mujeres, con 0,841 y 5,26 cm para todas las muestras, respectivamente. De acuerdo con estos resultados, la media del error absoluto del grupo de prueba osciló entre 3 y 5 cm. Por lo tanto, las ecuaciones de estimación de la estatura que utilizan la longitud y el ancho de los metatarsianos de nuestro estudio se pueden aplicar para estimar la estatura en la población tailandesa.

Descripción anatómica de los segmentos óseos que componen el esqueleto apendicular torácico de la especie Puma concolor / Anatomical description of the bony segments that make up the thoracic appendicular skeleton of the species Puma concolor

RESUMEN: El Puma concolor es uno de los carnívoros más grandes presentes en Chile, aunque su tamaño varía según la zona geográfica en la que se encuentra. Cada vez es más común encontrarlos fuera de su hábitat y más en nuestro entorno. Se conocen sus aspectos ecológicos, reproductivos y nutricionales, pero muy poco de su anatomía, lo que genera un desafío en el área morfológica veterinaria que necesita fortalecimiento. El presente estudio consistió en una descripción anatómica del esqueleto apendicular de tres ejemplares adultos de Puma concolor (3 machos) en el laboratorio de anatomía veterinaria de la Universidad San Sebastián, sede de la Patagonia Puerto Montt, lo que permitió un estudio detallado de la conformación del esqueleto de cada estructura presente en el esqueleto apendicular torácico de estos ejemplares. Esto nos permitió lograr resultados de interés morfológico y profundizar en la anatomía de esta especie.

SUMMARY: The Puma concolor is one of the largest carnivores present in Chile, although its size varies according to the geographical area in which it is found. It is increasingly common to find them outside their habitat and more in our environment. Its ecological, reproductive and nutritional aspects are known, but very little is known about its anatomy, which creates a challenge in the veterinary morphological area that needs strengthening. The present study consisted of an anatomical description of the appendicular skeleton of three adult specimens of Puma concolor (3 males) in the veterinary anatomy laboratory of the Universidad San Sebastián, headquarters of Patagonia Puerto Montt, which allowed a detailed study of the conformation of the skeleton of each structure present in the thoracic appendicular skeleton of these specimens. This allowed us to achieve results of morphological interest and delve into the anatomy of this species.

Bone bridges in the groove for middle meningeal artery / Puentes óseos en el surco para la arteria meníngea media

SUMMARY: The middle meningeal artery is an important vessel that is distributed in the endocranium region, between greater wing of sphenoid by the homonymous groove. There are few references on the formation of bone bridges in their trajectory, an aspect of relevance in morphology. The present study included 100 skulls -dried and whole heads- of adults, removing the calvaria, and identifying the spinous foramen, through which the middle meningeal artery courses to determine the existence or not of bone bridges -unilateral, bilateral or absence- for the passage of this artery. Of 100 adult skulls analyzed, it was found at the level of the medial aspect of the greater wing of the sphenoid bone and in its internal table, 73 % presented it and in 27 % there was absence. Of the specimens with bone bridges, 39 % were bilateral and of the latter, 34 % was unilateral and 16 % was on the right and 18 % on the left. The bony bridge for the middle meningeal artery is an anatomical constant that must be evaluated in anatomical, clinical and surgical considerations.

RESUMEN: La arteria meníngea media se distribuye en la región del endocráneo entre el ala mayor del esfenoides por el surco para dicha arteria. Existen pocas referencias sobre la formación de puentes óseos en su trayectoria, aspecto de relevancia en el campo morfológico. El presente estudio incluyó 100 cráneos -secos y cabezas enteras- de adultos, a los que se les extirpó la calvaria e identificó el foramen espinoso, por donde discurre la arteria meníngea media, para determinar la existencia o no de puentes óseos -unilaterales, bilaterales o ausenciaen su interior. De 100 cráneos adultos analizados, se encontró puentes óseos a nivel de la lámina medial del ala mayor del hueso esfenoides y en su tabla interna en un 73 % y en el 27 % no hubo. De las piezas con puentes óseos, el 39 % eran bilaterales y el 34 % eran unilaterales; el 16 % a la derecha y el 18 % a la izquierda. El puente óseo de la arteria meníngea media es una constante anatómica que debe ser evaluada en consideraciones anatómicas, clínicas y quirúrgicas.

Diferente asimetría craneal según sexo en el conejo toy / Different skull asymmetry according to sex in toy rabbits

RESUMEN: Los conejos denominados toy son seleccionados por su apariencia pedomórfica ('infantilizada'). El objetivo principal de este estudio fue analizar las asimetrías craneales en este tipo de conejo. Para ello, se estudiaron un total de 46 cráneos adultos (9 machos y 37 hembras), recurriéndose a técnicas de morfométrica geométrica a partir 10 hitos anatómicos pareados y 3 en el plano sagital, en la cara dorsal del cráneo. Nuestra hipótesis es que a través de la selección artificial en los machos (objetivo principal para la obtención de nuevos fenotipos) las asimetrías se expresarán como valores de asimetría más altos. El tamaño de los cráneos resultó similar entre ambos sexos, pero presentaban la asimetría fluctuante fue mayor en machos. La asimetría fluctuante se considera un indicador negativo de la capacidad de resistir pequeñas anomalías en su desarrollo, anomalías que son generalmente el resultado de estrés genético o ambiental. En otras palabras, los machos estarían sujetos a una selección más fuerte y, en consecuencia, se verían más afectados por el manejo, en comparación con las hembras. Estos resultados pueden facilitar la comprensión de los patrones y procesos subyacentes al dimorfismo sexual en fenotipos extremos, como lo son los de los conejos toy.

SUMMARY: Toy rabbits are selected for their paedomorphic ('babyish') appearance. The main objective of this study is to analyse the skull asymmetries of toy rabbits. For this purpose, a total of 46 adult skulls (9 males and 37 females) were studied. Geometric morphometric technique with five pairs of anatomical landmarks and three on sagittal plane on dorsal aspect of skull was used. Our hypothesis is that through artificial selection on males (which are the main subject for obtaining new phenotypes among toys) asymmetries will be expressed as higher asymmetrical values. Skulls' size was similar between sexes, but males presented a higher level of fluctuating asymmetry. Fluctuating asymmetry indicates a negative ability to buffer subtle developmental anomalies, normally from genetic or environmental origin. In other words, males would be under stronger directed selection and consequently be more affected by management (including selective) factors compared to females. These results can allow a better understanding of the patterns and processes underlying sexual shape dimorphism, especially with extreme phenotypes, as toy rabbits are.

Propuesta de clasificación de huesos suturales / Classification proposal of sutural bones

RESUMEN: Los huesos suturales tienen importancia anatómica y médico-legal. Se observan en las suturas de la cabeza ósea y tradicionalmente son descritos como planos, supernumerarios, irregulares, inconstantes, independientes y de variable morfología y frecuencia. Actualmente, no existe una clasificación única de estos huesos que incorpore todas las categorías descritas en la literatura. El objetivo de este trabajo fue proponer una clasificación actualizada de estos elementos, en función de una revisión bibliográfica exhaustiva y el análisis de cráneos de individuos chilenos. La muestra utilizada correspondió a 113 huesos suturales presentes en 12 cráneos secos, de individuos adultos chilenos. En la clasificación se consideró su ubicación en la cabeza (cráneo o cara), su origen embrionario, su relación con una fontanela, su forma, su posición en la cara y su relación con las tablas óseas. Los datos obtenidos se registraron en formulario especialmente diseñado y se tomaron fotografías digitales. Como resultado general, pudimos desarrollar una propuesta de clasificación de huesos suturales completa y satisfactoria y con ella se analizó los huesos de la muestra, pudiendo evidenciar la presencia de todas las categorías del instrumento. También pudimos constatar que en la totalidad de los cráneos utilizados se observaron huesos suturales, que los cráneos masculinos presentan un mayor número de estos huesos, pero que en los cráneos femeninos fue posible reconocer todas los tipos de huesos suturales, entre otros resultados. También se evidenció un tipo de hueso sutural no descrito anteriormente, el hueso sutural craneal puntiforme. Como conclusión de este trabajo, es importante destacar que los huesos suturales presentan características comunes a otras estructuras utilizadas en identificación forense, es decir, son perennes, únicos, de fácil observación, de fácil comparación y gran variabilidad, por estas razones la presente propuesta de clasificación permite ser planteada como una metodología auxiliar en la identificación humana.

SUMMARY: The sutural bones have anatomical and medico-legal importance. They are observed in the sutures of the bony head and are traditionally described as flat, supernumerary, irregular, inconstant, independent and of variable morphology and frequency. Currently, there is no single classification of these bones that incorporates all the categories described in the literature. The objective of this work was to propose an updated classification of these elements, based on an exhaustive bibliographic review and the analysis of the skulls of Chilean individuals. The sample used corresponds to 113 sutural bones present in 12 dry skulls of Chilean adults. The classification considers its location on the head (skull or face), its embryonic origin, its relationship to a fontanelle, its shape, its position on the face, and its relationship to bone tables. The data obtained was recorded in a specially designed format and digital photographs were taken. As a general result, we were able to develop a complete and satisfactory classification of sutural bones proposal and with it, the bones of the sample were analyzed, showing the presence of all categories of the instrument. We were also able to verify that sutural bones were observed in all the skulls used, that male skulls present a greater number of these bones, but that in the female skulls it was possible to recognize all types of sutural bones, among other results. A type of sutural bone not previously described, the shaped point cranial sutural bone, was also evidenced. As a conclusion to this work, it is important to highlight that sutural bones present characteristics common to other structures used in forensic identification, that is, they are perennial, unique, easily observed, easily compared and great variability, for these reasons the present classification proposal allows it to be proposed as an auxiliary methodology in human identification.

Anatomical characteristics of the bones of the thoracic limb of white-eared opossum (Didelphis albiventris) / Características anatómicas de los huesos del miembro torácico de la zarigüeya oreja blanca (Didelphis albiventris)

SUMMARY: The skeleton of the thoracic limb is one of the key aspects for the understanding of the habits and movement of different mammalian species. Considering the gap about studies related to marsupial osteology, this work proposes to study the aspects inherent to the skeleton of opossums, with emphasis on the detailed anatomical description of the bones that form the thoracic limb. For this purpose, the bones of six specimens of possums of the species Didelphis albiventris were used. These small to medium sized marsupials inhabit a wide range of South America, living in several types of habitats, being commonly described as arboreal omnivores and have anthropic habits. For the execution of this study, the bone accidents perceptible in the specimens were identified by superficial palpation, which were then radiographed. The thoracic limb bones were prepared by boiling and drying in the sun. Finally, from the radiographic images and the prepared bones, a detailed description of the anatomy of the bone components of the thoracic limb of Didelphis albiventris was made, joining the previously obtained data of surface anatomy. These data were compared with data from the literature, discussing the functional significance of the osteological findings of the thoracic limb of Didelphis albiventris.

RESUMEN: El esqueleto del miembro torácico es uno de los aspectos clave para el conocimiento de los hábitos y movimientos de las diferentes especies de mamíferos. Considerando los escasos estudios relacionados con la osteología marsupial, este trabajo se propusoestudiar los aspectos inherentes al esqueleto de la zarigüeya, con énfasis en la descripción anatómica detallada de los huesos que forman el miembro torácico. Para ello se utilizaron los huesos de seis ejemplares de zarigüeyas de la especie Didelphis albiventris. Estos marsupiales de pequeño a mediano tamaño habitan una zona amplia de América del Sur, viven en varios tipos de hábitats, se describen comúnmente como omnívoros arbóreos y tienen hábitos antrópicos. Para este estudio se identificaron mediante palpación superficial los accidentes óseos perceptibles en los especímenes, y posteriormente se tomaron imágens radiológicas. Los huesos de los miembros torácicos se prepararon hirviéndolos y secándolos al sol. Finalmente, a partir de las imágenes radiográficas y de los huesos preparados, se realizó una descripción detallada de la anatomía de los componentes óseos del miembro torácico de Didelphis albiventris, uniendo los datos de anatomía superficial obtenidos previamente. Estos datos se compararon con datos de la literatura, discutiendo la importancia funcional de los hallazgos osteológicos del miembro torácico de Didelphis albiventris.

A new miniature species of Priocharax (Characiformes: Characidae) from the upper rio Ipixuna, Purus drainage, Brazil

A new species of miniature fish of the characid genus Priocharax is described from a small lake near the rio Ipixuna, rio Purus drainage, Amazonas State, Brazil. It is distinguished from all congeners except P. pygmaeus by the lower number of teeth on the maxilla and dentary. It differs from P. pygmaeus by the presence of two postcleithra and 22-27 branched anal-fin rays (vs absence and 19-22). The new species is further distinguished from other species of Priocharax by a combination of characters involving the number of pelvic-fin rays and branched anal-fin rays, the number of postcleithra, the shape of postcleithrum 3, and the absence of the claustrum. Molecular evidence based on COI sequences of all valid species of Priocharax also corroborates the validity of this new species.(AU)

Uma nova espécie de peixe miniatura do gênero de caracídeo Priocharax é descrita de um pequeno lago próximo ao rio Ipixuna, drenagem do rio Purus, estados do Amazonas, Brasil. Ela difere de todas as congêneres, exceto P. pygmaeus pelo menor número de dentes no maxilar e dentário. Distingue-se de P. pygmaeus pela presença de dois pós-cleitros e 22-27 raios ramificados na nadadeira anal (vs ausência e 19-22). A nova espécie também difere de outras congêneres por uma combinação de caracteres como número de raios das nadadeiras pélvica e anal, número de pós-cleitros e formato do pós-cleitro 3, e ausência de claustrum. Evidências moleculares com base em sequências do gene COI de todas as espécies válidas também corrobora a validade da nova espécie.(AU)

La osteogénesis desde un marco filosófico: revisión de teorías y filosofías / Osteogenesis from a philosophical framework review of theories and philosophies

La osteología como práctica científica muestra, a través de su historia, los esfuerzos de los hombres de ciencia que pretendían explicar la entidad característica del hueso y sus procesos de formación. La extensión de esas investigaciones hace que se pierda el núcleo de lo que tiene la osteología de ciencia: las teorías osteológicas. Esta revisión historiográfica pretende ­con ayuda de la epistemología semántica­ presentar un esquema de red teórica que represente a algunos de esos modelos teóricos. (AU)

Osteology as a scientific practice shows through its history the efforts of scientists who tried to explain the characteristic entity of bone and its formation processes. The extension of these investigations causes that the nucleus of what the osteology of science has is lost: osteological theories. This historiographic review aims with the help of semantic epistemology to present a theoretical network scheme that represents some of these theoretical models. (AU)

Towards a complete classification of the Neotropical thorny catfishes (Siluriformes: Doradidae)

We propose a revised classification of Doradidae based on phylogenetic analyses of sequence data for one nuclear (rag1) and two mitochondrial (co1, 16s) genes, and corroborated by caudal-fin morphology. The molecular dataset comprises 174 doradid specimens representing all 31 valid genera, 83 of the 96 valid extant species and 17 species-level taxa that remain undescribed or nominally unassigned. Parsimony and Bayesian analyses of molecular data support six major lineages of doradids assigned here to three nominal subfamilies (Astrodoradinae, Doradinae, Wertheimerinae) and three new ones (Acanthodoradinae, Agamyxinae, Rhinodoradinae). The maximum parsimony topology of Doradidae was sensitive to ingroup density and outgroup age. With the exceptions of Astrodoradinae and Doradinae, each subfamily is diagnosed by caudal-fin characteristics. The highest degree of fusion among skeletal elements supporting the caudal fin is observed in Acanthodoradinae and Aspredinidae, lineages that are sister to the remaining doradids and aspredinoids (i.e., Auchenipteridae + Doradidae), respectively. Fusion among caudal-fin elements tends to be higher in taxa with rounded, truncate or emarginate tails and such taxa typically occupy shallow, lentic habitats with ample structure. Caudal-fin elements are more separated in taxa with moderately to deeply forked tails that occupy lotic habitats in medium to large river channels.(AU)

Propomos uma classificação revisada de Doradidae baseada na análise filogenética de dados moleculares dos genes rag1, co1 e 16s, e suportada pela morfologia da nadadeira caudal. A matriz molecular inclui 174 espécimes de doradídeos representando os 31 gêneros válidos, 83 das 96 espécies viventes e 17 táxons não descritos ou nominalmente não designados. As análises de parcimônia e bayesiana suportam seis linhagens principais de doradídeos atribuídas a três subfamílias nominais (Astrodoradinae, Doradinae, Wertheimerinae) e três novas subfamílias (Acanthodoradinae, Agamyxinae, Rhinodoradinae). A árvore de máxima parcimônia de Doradidae é sensível à densidade de grupo interno e a idade do grupo externo. Com exceção de Astrodoradinae e Doradinae, cada subfamília é diagnosticada por características da nadadeira caudal. Dentro da família Doradidae e da superfamília Aspredinioidea (Aspredinidae, Auchenipteridae e Doradidae), o maior grau de fusão entre os elementos da nadadeira caudal é observado nas linhagens mais antigas, Acanthodoradinae e Aspredinidae, respectivamente. A fusão entre os elementos da nadadeira caudal é maior em táxons com a caudal arredondada, truncada ou emarginada e esses táxons normalmente ocupam habitats lênticos rasos. Os elementos da nadadeira caudal são mais separados em táxons com a cauda bifurcada ocupando habitats lóticos em canais de rios médios a grandes.(AU)

Morphometric, anatomic and radiographic study of bone of the pelvic limb of endangered Patagonian huemul deer (Hippocamelus bisulcus) / Estudio morfométrico, anatómico y radiográfico de los huesos del miembro pélvico del huemul patagónico en peligro de extinción (Hippocamelus bisulcus)

Currently, the Patagonian huemul (Hippocamelus bisulcus) is endangered. Anatomical studies focused on understanding the anatomy of the deer most threatened by extinction in South America is a challenge for anatomists, veterinarians and biologists. Research carried out for its conservation has focused mainly on its ecology and pathology, leaving gaps in anatomical knowledge, which is basic and important for a comprehensive understanding of this species. Gross anatomy and radiography of the skeleton of the pelvic limb was performed in three adult Patagonian huemul. Bone specimens of three skeletally mature Patagonian huemul deer were used for gross osteological and radiographic studies. This study was conducted to reveal the morphometric and morphological features of the ossa membri pelvini of the Patagonian huemul. The main findings suggest the presence of powerful extensor muscles in the coxofemoral, femorotibial and tarsal joints, useful during walking, jogging and propulsion in deer. In general, the MNF of Patagonian huemul differ in position with respect to domestic ungulates. In addition, the presence of a notch or obturator canal was observed, with variability in morphology and development among the specimens.

Actualmente, el Huemul Patagónico (Hippocamelus bisulcus) está en peligro de extinción. Los estudios morfológicos centrados en comprender su anatomía han sido un desafío para morfólogos, veterinarios y biólogos. Investigaciones enfocadas en su conservación, se han centrado principalmente en su ecología, patología y en la descripción de sus principales agentes infecciosos, dejando vacíos en el conocimiento anatómico básico, y por ende, su comprensión morfofisiológica. El objetivo de este estudio fue describir la anatomía, morfometría y radiología macroscópica normal y detallada del ossa membri pelvini en tres especímenes de Huemul Patagónico, incluida una interpretación funcional como referencia para uso clínico y conservacionista, investigación biomédica y fines de enseñanza. Los principales hallazgos sugieren la presencia de potentes músculos extensores en las articulaciones coxofemoral, femorotibial y tarsal, útiles durante la marcha, el trote y la propulsión en los ciervos. En general, los forámenes nutricios principales del Huemul patagónico difieren en posición con respecto a los ungulados domésticos. Además, se observó la presencia de una muesca o canal obturador, con variabilidad morfológica y de desarrollo entre los especímenes.

Taxonomic review of the typical long-snouted species of Corydoras (Siluriformes: Callichthyidae) from the río de La Plata basin

The typical long-snouted species of Corydoras from the río de La Plata basin were reviewed herein, and the previously proposed synonymy of Corydoras ellisae was corroborated. Corydoras areio and C. aurofrenatus are diagnosed from their congeners, excluding those in lineage 1, by the following features: temporal sensory canal in sphenotic with two pores; upper tooth plate of branchial arch with three or four series of teeth; fleshy flap at mouth corner. Corydoras areio differs from all lineage 1 congeners by having infraorbital 2 with relatively wider posterior laminar expansion; absence of large patches of black pigmentation on the body and absence of conspicuous concentration of dark brown or black chromatophores on anterior portion of the dorsal fin; and presence of blotches on flanks not aligned in longitudinal series. Corydoras aurofrenatus differs from all lineage 1 congeners by having ventral surface of head and trunk densely covered by small, not coalescent platelets; middle portion of flank with two or three dark brown or black patches (below the dorsal-fin, below the adipose-fin base, and on the caudal peduncle base, diffuse and variably present), patches decreasing in size posteriorly; poorly developed fleshy flap at the corner of mouth; anteroventral portion of cleithrum exposed.(AU)

As espécies típicas de focinho longo de Corydoras da bacia do río de La Plata foram revisadas, e a sinonímia proposta anteriormente de Corydoras ellisae foi corroborada. Corydoras areio e C. aurofrenatus são diagnosticadas de seus congêneres, excluindo aquelas da linhagem 1, pelas seguintes características: canal sensorial temporal no esfenótico com dois poros; placa dentária superior do arco branquial com três ou quatro séries de dentes; aba carnosa no canto da boca. Corydoras areio difere de todos os congêneres da linhagem 1 pelo infraorbital 2 com expansão laminar posterior relativamente mais ampla; ausência de grandes manchas de pigmentação preta no corpo e ausência de concentração conspícua de cromatóforos marrom-escuros ou pretos na porção anterior da nadadeira dorsal; presença de manchas laterais não alinhadas em série longitudinal. Corydoras aurofrenatus difere de todas as congêneres da linhagem 1 pela superfície ventral da cabeça e do tronco densamente coberta por pequenas plaquetas não coalescentes; porção média lateral com duas ou três manchas marrom-escuras ou pretas (abaixo da nadadeira dorsal, abaixo da base da nadadeira adiposa, e na base do pedúnculo caudal, difusa e variavelmente presente), manchas diminuindo de tamanho posteriormente; aba carnosa pouco desenvolvida no canto da boca; porção anteroventral do cleitro exposta.(AU)

Comparación y caracterización morfométrica del híbrido (Pseudoplatystoma metaense x Leiarius marmoratus) y sus parentales (Siluriformes: Pimelodidae) / Morphometric comparison and characterization of the hybrid (Pseudoplatystoma metaense x Leiarius marmoratus) and its parental lines (Siluriformes: Pimelodidae)

La diversificación en la oferta de la piscicultura, ha llevado a la hibridación de especies de alto valor comercial, como los grandes bagres de la familia Pimelodidae, en busca del mejoramiento de características relevantes. Sin embargo, uno de los principales problemas de ésta práctica, es que morfológicamente los híbridos son similares a los parentales o con formas intermedias difíciles de diferenciar. Las nuevas herramientas morfométricas como la geometría han logrado evaluar cuantitativamente los cambios morfológicos, coadyuvando a esclarecer problemas de diferenciación morfológica. Con el fin de evaluar las relaciones morfométricas y establecer si, las características analizadas son intermedias en el híbrido con respecto a los parentales, se realizó la caracterización morfométrica de 20 ejemplares adultos de Pseudoplatystoma metaense, 21 de Leiarius marmoratus y 12 del híbrido Pseudoplatystoma metaense x Leiarius marmoratus, para un total de 53 individuos evaluados. Se realizaron análisis de morfometría lineal, utilizando medidas corporales y craneales, sustentadas en los análisis de componentes principales y discriminantes, como una forma de evaluar el contorno de los ejemplares. Para el análisis osteológico, se utilizó el neurocráneo, obtenido mediante el protocolo de maceración; con fotografías, éstos fueron analizados mediante morfometría geométrica con los programas de la serie IMP. De esta forma, se encontró que las similitudes observadas a simple vista en el híbrido respecto a sus parentales, no son representativas y por lo tanto, estadísticamente se evidenciaron tres grupos morfológicos definidos que separan a las especies parentales y el híbrido, obteniendo así, una herramienta de fácil identificación. En el análisis osteológico, se encontraron similitudes entre los neurocráneos del híbrido y de Pseudoplatystoma metaense, lo que plantea un patrón de herencia en el que se pueden evaluar posibles convergencias y divergencias como consecuencia de la hibridación.

Diversification in the supply of fish farming has led to the hybridization of high commercial value species, such as the large catfish of the Pimelodidae family, in search of the improvement of relevant characteristics. However, one of the main problems of this practice is that morphologically the hybrids are similar to the parental lines or with intermediate forms difficult to differentiate. The new morphometric tools as geometry have managed to quantitatively evaluate the morphological changes, contributing to clarify problems of morphological differentiation. In order to evaluate the morphometric relationships and establish whether, the analyzed characteristics are intermediate in the hybrid with respect to the parental lines, the morphometric characterization of 20 adult specimens of Pseudoplatystoma metaense, was performed 21 of Leiarius marmoratus and 12 of the hybrid Pseudoplatystoma metaense x Leiarius marmoratus, for a total of 53 individuals evaluated. Linear morphometry analyses were performed, using body and cranial measurements, sustained in the analysis of principal and discriminating components, as a way of evaluating the contour of the specimens. For the osteological analysis, the neurocranium was used, obtained by means of the maceration protocol; with photographs; these were analyzed using geometric morphometry with the programs of the IMP series. Thus, it was found that the similarities observed at first sight in the hybrid with respect to their parentals, are not representative and therefore, statistically, three defined morphological groups that separate the parental species and the hybrid, thus obtaining an easy-to-identify tool. In the osteological analysis, similarities were found between the neurocraniums of the hybrid and Pseudoplatystoma metaense, which raises a pattern of inheritance in which possible convergences and divergences can be evaluated, as a result of hybridization.

Anatomia óssea e muscular do antebraço e mão de Chrysocyon brachyurus (carnivora, canidae) / Bone and muscular anatomy of the antibone and hand of Chrysocyon brachyurus (carnivora, canidae)

O lobo-guará Chrysocyon brachyurus Illiger, 1815, é o maior canídeo da América do Sul, pesa cerca de 25 kg quando adulto e está ameaçado de extinção. Descrições anatômicas contribuem para a complementação das informações sobre espécies silvestres e para implicações conservacionistas, clínicas e cirúrgicas. Objetivou-se descrever os ossos e os músculos do antebraço e mão do lobo-guará. A preparação das peças foi feita a partir dos métodos usuais de dissecação, em animais preservados em solução de formol a 10%. Os espécimes pertencem ao acervo didático do Laboratório de Ensino e Pesquisa em Animais Silvestres da UFU e são provenientes de indivíduos atropelados. Os ossos descritos foram: rádio, ulna, ossos cárpico acessório, cárpico ulnar e cárpico intermédio; ossos cárpicos I, II, III e IV; ossos metacárpicos I, II, III, IV, V; falanges proximais, falanges médias e falanges distais do primeiro ao quinto dedo. Os músculos observados foram: extensor radial do carpo; pronador redondo; braquiorradial; extensor comum dos dedos; extensor ulnar do carpo; extensor lateral dos dedos;supinador; abdutor longo do dedo I; flexor radial do carpo; flexor profundo dos dedos; flexor superficial dos dedos; flexor ulnar do carpo; pronador quadrado; interflexor; lumbricais; abdutor curto dos dedos I e II e flexor curto do dedo I.

The maned wolf Chrysocyon brachyurus (Illiger, 1815) is the largest canid in South America, weighs about 25 kg as an adult and is threatened of extinction. Anatomical descriptions contribute to the complementation of information on wild species and for conservation, clinical and surgical implications. The purpose of this study was to describe the bones and muscles of the forearm and hand of the maned wolf. The methodology was through the usual dissecting methods in animals preserved in 10% formalin solution. The animals belong to the didactic collection of the Laboratory of Teaching and Research in Wild Animals of the UFU and come from run over. The bones evaluated were: radius, ulna, carpal accessory, carpi ulnar and carpi intermedium; carpal bones I, II, III and IV; metacarpal bones I, II, III, IV, V; proximal phalanges, middle phalanges and distal phalanges from first to fifth finger. The muscles observed were: radial extensor carpal; pronator round; brachioradial; common extensor of fingers; ulnar carpal extensor; lateral extensor of the fingers; supinator; abductor long finger I; flexor carpi radialis; flexor deep fingers; superficial flexor of the fingers; ulnar flexor of the carpus; square pronator; interflexor; lumbrils; short abductor of fingers I and II and short flexor of finger I.

Anatomia óssea e muscular do antebraço e mão de Chrysocyon brachyurus (Carnivora, Canidae) / Bone and muscular anatomy of the antibone and handof Chrysocyon brachyurus (Carnivora, Canidae)

O lobo-guará Chrysocyon brachyurus Illiger, 1815, é o maior canídeo da América do Sul, pesa cerca de 25 kg quando adulto e está ameaçado de extinção. Descrições anatômicas contribuem para a complementação das informações sobre espécies silvestres e para implicações conservacionistas, clínicas e cirúrgicas. Objetivou-se descrever os ossos e os músculos do antebraço e mão do lobo-guará. A preparação das peças foi feita a partir dos métodos usuais de dissecação, em animais preservados em solução de formol a 10%. Os espécimes pertencem ao acervo didático do Laboratório de Ensino e Pesquisa em Animais Silvestres da UFU e são provenientes de indivíduos atropelados. Os ossos descritos foram: rádio, ulna, ossos cárpico acessório, cárpico ulnar e cárpico intermédio; ossos cárpicos I, II, III e IV; ossos metacárpicos I, II, III, IV, V; falanges proximais, falanges médias e falanges distais do primeiro ao quinto dedo. Os músculos observados foram: extensor radial do carpo; pronador redondo; braquiorradial; extensor comum dos dedos; extensor ulnar do carpo; extensor lateral dos dedos; supinador; abdutor longo do dedo I; flexor radial do carpo; flexor profundo dos dedos; flexor superficial dos dedos; flexor ulnar do carpo; pronador quadrado; interflexor; lumbricais; abdutor curto dos dedos I e II e flexor curto do dedo I.

The maned wolf Chrysocyon brachyurus (Illiger, 1815) is the largest canid in South America, weighs about 25 kg as an adult and is threatened of extinction. Anatomical descriptions contribute to the complementation of information on wild species and for conservation, clinical and surgical implications. The purpose of this study was to describe the bones and muscles of the forearm and hand of the maned wolf. The methodology was through the usual dissecting methods in animals preserved in 10% formalin solution. The animals belong to the didactic collection of the Laboratory of Teaching and Research in Wild Animals of the UFU and come from run over. The bones evaluated were: radius, ulna, carpal accessory, carpi ulnar and carpi intermedium; carpal bones I, II, III and IV; metacarpal bones I, II, III, IV, V; proximal phalanges, middle phalanges and distal phalanges from first to fifth finger. The muscles observed were: radial extensor carpal; pronator round; brachioradial; common extensor of fingers; ulnar carpal extensor; lateral extensor of the fingers; supinator; abductor long finger I; flexor carpi radialis; flexor deep fingers; superficial flexor of the fingers; ulnar flexor of the carpus; square pronator; interflexor; lumbrils; short abductor of fingers I and II and short flexor of finger I.

Anátomo-radiografia dos ossos longos do membro torácico do Tamandua tetradactyla / Anatomo-radiography of long-bones in thoracic limb ofTamandua tetradactyla

Objetivou-se descrever os acidentes anatômicos dos ossos longos do membro torácico de Tamandua tetradactyla por meio de análises macroscópicas e radiográficas. Foram utilizados 34 espécimes, que foram a óbito por atropelamento. A avaliação do úmero demonstrou as mesmas estruturas presentes nos animais domésticos, além de outras sem prévia descrição. Já no antebraço, rádio e ulna se apresentaram completamente separados, e apesar de, como o úmero, serem identificados alguns dos mesmos acidentes anatômicos descritos em outras espécies, também notamos particularidades. Todas as estruturas descritas na análise macroscópica foram identificadas à radiografia, quando realizada em pelo menos duas projeções ortogonais. As estruturas anátomo-radiográficas dos ossos longos do T. tetradactyla demonstraram grande variação anatômica em comparação a outros mamíferos, o que torna a referida espécie muito singular. Assim o conhecimento de suas particularidades é fundamental para abordagens clínico-cirúrgicas mais seguras.

The objective was to describe the anatomical accidents of the long bones of the thoracic limb of Tamandua tetradactyla by means of macroscopic and radiographic analyzes. We used 34 specimens, which were deaths by running over. Evaluation of the humerus demonstrated the same structures present in domestic animals, besides others without previous description. In the forearm, radius and ulna were completely separated, and although, like the humerus, some of the same anatomical accidents described in other species were identified, we also noticed particularities. All the structures described in the macroscopic analysis were identified on radiography, when performed in at least two orthogonal projections. The anatomic-radiographic structures of the long bones of T. tetradactyla showed great anatomical variation compared to other mammals, which makes the species very unique. Thus knowledge of their particularities is fundamental for safer clinical-surgical approaches.

Anátomo-radiografia dos ossos longos do membro torácico do Tamandua tetradactyla / Anatomo-radiography of long-bones in thoracic limb of Tamandua tetradactyla

Objetivou-se descrever os acidentes anatômicos dos ossos longos do membro torácico de Tamandua tetradactyla por meio de análises macroscópicas e radiográficas. Foram utilizados 34 espécimes, que foram a óbito por atropelamento. A avaliação do úmero demonstrou as mesmas estruturas presentes nos animais domésticos, além de outras sem prévia descrição. Já no antebraço, rádio e ulna se apresentaram completamente separados, e apesar de, como o úmero, serem identificados alguns dos mesmos acidentes anatômicos descritos em outras espécies, também notamos particularidades. Todas as estruturas descritas na análise macroscópica foram identificadas à radiografia, quando realizada em pelo menos duas projeções ortogonais. As estruturas anátomo-radiográficas dos ossos longos do T. tetradactyla demonstraram grande variaçãoanatômica em comparação a outros mamíferos, o que torna a referida espécie muito singular. Assim o conhecimento de suas particularidades é fundamental para abordagens clínico-cirúrgicas mais seguras.

The objective was to describe the anatomical accidents of the long bones of the thoracic limb of Tamandua tetradactyla by means of macroscopic and radiographic analyzes. We used 34 specimens, which were death by running over. Evaluation of the humerus demonstrated the same structures present in domestic animals, besides others without previous description. In the forearm, radius and ulna were completely separated, and although, like the humerus, some of the same anatomical accidents described in other species were identified, we also noticed particularities. All the structures described in the macroscopic analysis were identified on radiography, when performed in at least two orthogonal projections. The anatomic-radiographic structures of the long bones of T. tetradactyla showed great anatomical variation compared to other mammals, which makes the species very unique. Thus knowledge of their particularities is fundamental for safer clinical-surgical approaches.

Osteometric and radiological study of the mandibular notch / Estudio osteométrico y radiológico de la incisura mandibular

The mandibular notch is located on the superior margin, between two prominent processes of the mandibular ramus, the coronoid and condylar processes. The mandibular notch permits the entry of the masseteric artery, vein and nerve to the deep surface the masseteric muscle. Literary reports documented variations in both, the shape and size of the mandibular notch. Therefore, this study aimed to document the morphology and morphometry of the mandibular notch in the South African Black and Indian population groups and to determine their relationship to sex, age and race (if any). The morphometric and morphological parameters of the mandibular notch were measured and assessed in 149 digital panoramic radiographs and 51 dry mandible specimens (n=400) belonging to the South African Black African and Indian population groups. A combination of classification schemes by Mohammad et al. (2012) and Shakya et al. (2013) were adopted to assess the morphology of the mandibular notch. The morphometric parameter was measured using the Dicom x-ray viewer and a digital vernier caliper. Each of the morphometric and morphological parameters were statistically analyzed using SPSS, to determine if a relationship existed between the afore-mentioned parameters and sex, age and race. This study recorded the round shaped mandibular notch to be the most prevalent type in both sexes with a combined incidence of 44.2 %. The length of the mandibular notch was reported to be greater in males than females and concurred with previous studies. However, the selected South African group displayed a smaller mandibular notch than the Japanese and Chinese population groups. Furthermore, this study documented population differences among the South African population group, as the Black African population group showed a wider mandibular notch than the Indian population group. This suggests that population-specific differences may exist for both the morphological and morphometric parameters of the mandibular notch. However, only a statistically significant relationship between the length of the mandibular notch with age and race was documented. The mandibular notch may be of clinical significance to maxillofacial surgeons for surgical and reconstructive procedures, in addition it may also aid forensic anthropologists in the identification of unknown remains.

La incisura mandibular se encuentra en el margen superior, entre dos procesos importantes de la rama mandibular, el proceso coronoides y el proceso condilar. La incisura mandibular permite la entrada de la arteria, la vena y el nervio masetérico en la superficie profunda del músculo masetero. En la literatura se han documentado variaciones tanto en la forma como en el tamaño de la incisura mandibular. Este estudio tuvo como objetivo documentar la morfología y la morfometría de la incisura mandibular en los grupos de población de negros e indios sudafricanos y determinar su relación con el sexo, la edad y la raza. Los parámetros morfométricos y morfológicos de la incisura mandibular se midieron y evaluaron en 149 radiografías panorámicas digitales y 51 especímenes de mandíbula seca (n = 400) pertenecientes a los grupos de población sudafricana negra e india. Una combinación de esquemas de clasificación de Mohammad et al. (2012) y Shakya et al. (2013) fueron adoptados para evaluar la morfología de la incisura mandibular. El parámetro morfométrico se midió utilizando el visor de rayos X Dicom y un calibrador Vernier digital. Cada uno de los parámetros morfométricos y morfológicos se analizaron estadísticamente utilizando el software SPSS, para determinar si existía una relación entre los parámetros mencionados anteriormente y el sexo, la edad y la raza. Este estudio registró la incisura mandibular de forma redonda como el tipo más prevalente en ambos sexos, con una incidencia de un 44,2 %. Se informó que la longitud de la incisura mandibular es mayor en hombres que en mujeres y coincidió con estudios anteriores. Sin embargo, el grupo sudafricano seleccionado mostró una incisura mandibular más pequeña que los grupos de población japoneses y chinos. Además, se documentó las diferencias de población entre el grupo de Sudáfrica, ya que el grupo de población negra de África mostró una incisura mandibular más amplia que el grupo de la población India. Esto sugiere que pueden existir diferencias específicas de la población para los parámetros morfológicos y morfométricos de la incisura mandibular. Sin embargo, solo se documentó una relación estadísticamente significativa entre la longitud de la incisura mandibular con la edad y la raza. La incisura mandibular puede ser de importancia clínica para los cirujanos maxilofaciales en procedimientos quirúrgicos y reconstructivos; además, también puede ayudar a los antropólogos forenses en la identificación de restos desconocidos.

A new species of Paralithoxus (Siluriformes: Loricariidae: Ancistrini) from the highlands of Serra da Mocidade, Roraima State, Brazilian Amazon

A new species of Paralithoxus is described from the Ajarani River, a small tributary of the Branco River basin, Roraima State, Brazilian Amazon. The genus Paralithoxus comprises species described from the Essequibo drainage in Guyana, Approuague and Maroni in French Guiana, Suriname River in Surinam, and more recently, from Jari and Amapá rivers, in Brazil. Despite occurring in a rock-bottomed fast-flowing stream as the other species of Paralithoxus, this is the first species of the genus collected at 900 m altitude, in the Serra da Mocidade highlands, an isolated and poorly accessible small mountain chain at the southern border of the Guiana Shield. The new species is distinguished from its congeners by having truncate teeth, color pattern with green spots on dark olive-brown background, alternating dark and light blotches on fins and by the pelvic fin being as long as or longer than the pectoral fin. Sex dimorphism of the species is described. Comments on morphology and osteology are provided and compared with congeners.(AU)

Uma nova espécie de Paralithoxus é descrita do rio Ajarani, um pequeno tributário da bacia do rio Branco, Estado de Roraima, Amazônia Brasileira. O gênero Paralithoxus é composto por espécies descritas para as drenagens do Essequibo na Guiana, Approuague e Maroni na Guiana Francesa, rio Suriname no Suriname, e mais recentemente, para os rios Jari e Amapá, no Brasil. Apesar de ocorrer em pequenos riachos com fundo rochoso e correnteza forte como o restante dos representantes de Paralithoxus, esta é a primeira espécie do gênero coletada a 900 m de altitude, na Serra da Mocidade, uma pequena cadeia de montanhas localizada em uma área isolada e de difícil acesso na porção sul do Escudo das Guianas. A nova espécie distingue-se de suas congêneres pela presença de dentes truncados, pelo padrão de coloração com manchas verde claras sobre fundo oliva-marrom escuro, alternando manchas claras e escuras nas nadadeiras e pelo comprimento relativo da nadadeira pélvica igual ou maior que o comprimento da nadadeira peitoral. O dimorfismo sexual da espécie é descrito. Comentários sobre a morfologia e osteologia da espécie são feitos e comparados com suas congêneres.(AU)