Lateral Teeth Research Articles

Tek Taraflı Maksiller Palatal Gömülü Kanine Sahip Bireylerde Dentoalveolar Ark Simetrisinin Karşılaştırılması

Objective: To compare the dentoalveolar measurements of the subjects with unilateral palatally impacted canines versus nonimpacted contralateral side on cone-beam computed tomography. Material and Methods: This retrospective study comprised 27 patients (16 female, 11 male; mean age: 15.34±1.95 years) with unilateral palatally impacted canine. Dolphin imaging software was used to reconstruct coronal, sagittal, and axial images. Coronal images were used for the evaluation of the angulation of the canine and lateral teeth, dentoalveolar height from the central and lateral incisors. On sagittal images, canine, lateral, first premolar angulation, and the distance of the canine cusp tip to the occlusal plane, on axial images; the lateral incisor rotation and arch width from premolar to mid-palatine raphe were evaluated. The paired samples t-test and Pearson correlation analysis were used for the statistical evaluation. Results: Lateral incisors on the impacted side showed significantly higher coronal angulation and lower sagittal angulation, compared to the non-impacted side (p<0.05). On impacted side, axial width from the first premolar to the mid-palatine raphe and lateral incisor rotation was significantly lower than on the non-impacted side (p≤0.001). Canine cusp tip-occlusal plane was negatively correlated with the dentoalveolar height of the central (r=-0.400; p=0.039) and lateral incisors (r=-0.373; p=0.055). Conclusion: The results of the study implicate that unilateral palatally impacted maxillary canines can provide asymmetric dentoalveolar measurements. The deviation of the lateral incisors from normal angulation should be taken into consideration during orthodontic examination.

Hybrid ameloblastoma and central giant cell lesion: Challenge of early diagnosis

Hybrid lesions encompass the occurrence of different entities in one lesion. A 67-year-old woman was referred to the Oral and Maxillofacial Surgery Service for treatment of mandibular Central Giant Cell Lesion (CGCL) previously diagnosed. Intraoral examination revealed edentulism and a painless swelling extending from the alveolar ridge to the buccal vestibule with hard consistency covered by normal mucosae, with unknown duration. Panoramic radiograph revealed a large, multilocular and well-defined radiolucent lesion extending from the region of left mandibular lateral incisor teeth to right mandibular first molar with no evidence of osseous perforation. Initially, a treatment with intralesional injection of corticosteroids was performed. After 18 months of treatment, an increase in size of the osteolytic lesion was noted. An incisional biopsy was carried out and the microscopic examination revealed a unicystic ameloblastoma associated to CGCL. It was performed marsupialization and later the enucleation of residual lesion. The follow-up remains being performed. Key words:Hybrid lesion, central giant cell lesion, ameloblastoma.

Early childhood tooth bud removal practice (“Ibyinyo”): preventable dental damage

Tooth bud removal called Ibyinyo is the practice of removing the developing tooth buds, usually done on an infant, typically performed by traditional healers who believe that this practice will reduce fever and diarrhoea in children. This practice is most prevalent in East-African countries, including Rwanda. These procedures are mostly performed in non-sterile conditions using basic sharp instruments. We will discuss the case of a 10-year-old female patient who was presented at the dental clinic, with two malformed permanent canine teeth. Clinical examination revealed malformed enamel and elongated permanent right maxillary canine tooth left mandibular canine tooth with crown malformation. She was also presented with retained (primary) left maxillary lateral incisor tooth and missing left maxillary canine tooth. In addition, the ectopic eruption of left maxillary central incisor tooth and missing permanent right mandibular canine tooth were noted. All these complications resulted from tooth bud removal that the patient had experienced in her early childhood. Her malformed right maxillary and left lower mandibular canine teeth were reshaped, using composite filling materials, to improve her appearance aesthetically. Ibyinyo is preventable damage, done out of ignorance and superstitious practices that can be stopped by growing social awareness. Therefore, educating parents through community-based campaigns on the detrimental consequences of early childhood tooth bud removal through Ibyinyo practice might be helpful to eradicate this harmful and unnecessary practice.

Circadian dynamics in the functional interaction of the lateral teeth occlusal surfaces' relief.

This study describes the relationship of the chronophysiological organization of the lateral teeth occlusion and the parameters of the chewing unit of the human dentofacial system (bioelectric potentials, the force of the masticatory muscles, masticatory efficiency) which should be considered in modeling of prosthesis occlusal surfaces. Examination of 200 respondents with a "day" chronotype, with Angle class I bilateral occlusion at the age of 18-35 years was conducted daily for 3 days. From 8.00 to 20.00, every 4 hours, the amplitude of the electromyography, the jaw muscles' force, the masticatory efficiency, the area of the occlusal contacts, and the near-contact zones were determined. The activity of the masticatory muscles increased during the period from 12.00 to 16.00, which coincided with the escalation of the masticatory efficiency and of the occlusal contacts area. The relationship between the occlusal surfaces' relief and masticatory efficiency is described by two types of occlusal surfaces' topography - smoothed and pronounced, differing by the ratio of the areas of the occlusal contacts and the near-contact zones in 0.25- and 1-mm wide. The modeling of the occlusal surface of the permanent prosthetic restorations for patients with the "day" chronotype should be carried out with the area values of occlusal contacts and near-contact zones corresponding to the period of masticatory muscles activity from 12.00 to 16.00 and in accordance with the characteristic type of the occlusal surfaces' relief.

The prevalence and distribution of hypodontia in 9-16 years old children

Aim: Hypodontia is one of the most common dentofacial malformations that affect individuals, both aesthetically and functionally. Hypodontia or congenitally missing teeth is among dental anomalies with different prevalence in each region. This study aimed to evaluate the prevalence of congenital permanent teeth deficiency according to gender, age and number of missing teeth in children aged 9-16 years.Material and Methods: In this study, hypodontia cases were examined retrospectively from the panoramic radiographs of patients aged 9-16 years who applied to the Department of Pedodontics of Harran University Faculty of Dentistry between 2018-2019. Age, gender, count and number of missing teeth, jaw and side of the missing tooth were recorded. Descriptive statistical analysis and Chi-square test were used for statistical analysis of the obtained data.Results: Of the 1036 patients included in our study, 52% (539) were male, and 48% (497) were female. The age average of the patients, whose radiographies were evaluated, was 11. Congenital tooth deficiency (hypodontia) was found in 68 patients, i.e. 6.6% of patients. A total of 123 teeth were missing in 68 patients. Twenty-four of the patients with hypodontia were male, and 44 were female. The relationship between gender and hypodontia was examined by chi-square test, and the result was statistically significant (p 0.05). Mostly missing teeth are respectively; lower second premolar teeth (40.6%), upper lateral teeth (29.3%) and upper second premolar teeth (9.8%). Conclusion: In our study, the prevalence of hypodontia cases was found to be 6.6% in Sanliurfa, Turkey. Early diagnosis of such a common dental anomaly can lead to successful functional and aesthetic results in a multidisciplinary study. Therefore, dental examinations and radiographic imaging in early childhood are crucial.

Low-intensity pulsed ultrasound enhances the rate of lateral tooth movement and compensatory bone formation in rats

Because mechanical stimulation of the periodontal ligament by low-intensity pulsed ultrasound (LIPUS) has been shown to increase the speed of bone remodeling, this study aimed to examine the effects of LIPUS stimulation on the rate of tooth movement and bone remodeling during lateral tooth movement. Twelve-week-old Wistar rats were divided into 2 groups. The LIPUS group received experimental tooth movement with LIPUS stimulation, and the tooth movement (TM) group were provided experimental tooth movement without LIPUS. For each group, the upper right first molars were moved buccally with fixed appliances. LIPUS exposure was placed in the region corresponding to the right maxillary first molar. Three days after tooth movement, tartrate-resistant acid phosphatase was examined. Fourteen days after tooth movement, the intermolar width, bone mineral content, and bone volume fraction were analyzed by micro-computed tomography, and newly formed bone was measured histomorphometrically. The number of TRAP-positive cells in the compressed region was higher in the LIPUS group. The intermolar width was significantly higher in the LIPUS group than in the TM group. The alveolar bone around the maxillary first molar showed no differences in bone mineral content and bone volume fraction between the LIPUS and TM groups. The LIPUS group exhibited a more significant amount of newly formed alveolar bone than the TM group. The present study provides evidence of the beneficial effects of LIPUS on the lateral tooth movement.

Porella perrottetiana var. angustifolia (Porellaceae, Marchantiophyta), new to China, and taxonomic revision of Porella perrottetiana in the East Yunnan-Guizhou Plateau

Cao, W., Xiong, Y.-X., Zhao, D.-G., Qu, J.-J. & Tan, H.-Y. 2019. Porella perrottetiana var. angustifolia (Porellaceae, Marchantiophyta), new to China, and taxonomic revision of Porella perrottetiana in the East Yunnan-Guizhou Plateau. – Herzogia 32: 344 –356.Porella perrottetiana var. angustifolia (Porellaceae, Marchantiophyta), a neglected variety known from North Vietnam, is reported here as a new addition to the Chinese liverwort flora from east of the Yunnan-Guizhou Plateau, SW China. It is characterized and distinguished from known Chinese species of Porella by attenuately ligulate or lanceolate and falcate leaf lobes with a long terminal and 0 – 4(–5) lateral ciliate teeth, median cells significantly larger than marginal cells, and by forming vitta from base to apex of leaf lobes. Detailed illustrations and description of this variety, an identification key to three varieties of Porella perrottetiana as well as a taxonomic revision of Porella perrottetiana in east of the Yunnan-Guizhou Plateau are provided.

&lt;p class="Body"&gt;&lt;strong&gt;Molecular and ontogeny studies clarify systematic status of &lt;em&gt;Chamobates borealis &lt;/em&gt;(Acari, Oribatida, Chamobatidae): an integrated taxonomy approach&lt;/strong&gt;&lt;/p&gt;

Chamobates borealis (Trägårdh 1902) has been considered by some authors as a junior synonym of Chamobates pusillus (Berlese 1895). In this study we used an integrated taxonomy approach, comparing mitochondrial coding gene COI and morphological ontogeny of these species to clarify their systematic status. The Bayesian inference tree based on COI sequences of C. borealis and C. pusillus, as well as C. birulai (Kulczyński 1902), C. bispinosus Mahunka, 1987, C. cuspidatus (Michael 1884) and C. rastratus (Hull 1914) separated all these species. In terms of the morphology, the adults of C. borealis and C. pusillus have similar body size and shape, thin aggenital setae and two lateral teeth on the rostrum, but C. borealis has the medial incision between these teeth, which is absent in C. pusillus. The adults of these species differ also from each other by the shape of bothridial setae, size of area porose Aa, location of seta lm and lyrifissure im, and the shape of most setae on the hysterosoma. The morphological ontogeny of these species is similar, but the larva and nymphs of C. borealis differ from those of C. pusillus by the length of some prodorsal and gastronotal setae, and the nymphs of C. borealis have a humeral organ, which is absent in C. pusillus. The presence of a humeral organ in some Chamobates species supports a clade inferred by COI sequence data.

A large sized megalosaurid (Theropoda, Tetanurae) from the late Jurassic of Uruguay and Tanzania

We report the first Jurassic remains that can confidently be referred to a megalosaurine theropod in Uruguay and Tanzania. This identification is sustained on a detailed morphological study. The large size of both teeth (>70 mm in lateral teeth) and denticles (<7 denticles per 5 mm), the clearly visible braided enamel texture, the centrally placed and apically restricted mesial carina in mesial teeth, and general shape of the teeth strongly resembles Torvosaurus. This is coherent with multivariate analyses of two datasets of large theropod teeth measurements, and also with the results of a phylogenetic analysis of theropod teeth. The presence of Torvosaurus in the Tacuarembó Formation of Uruguay further strengthens the Late Jurassic age proposed for the fossiliferous horizon. The Uruguayan megalosaurid would represent the apex predator in the vertebrate assemblage. The occurrence of megalosaurids in the Late Jurassic of Uruguay (the first unquestionable megalosaurid from South America) and Tanzania also greatly expands the geographical range of the family.

Unloved, paraphyletic or misplaced: new genera and species of small to minute lucinid bivalves and their relationships (Bivalvia, Lucinidae).

Species identified as Pillucina are paraphyletic in molecular analyses and a new generic name, Rugalucina, is introduced for a complex of three similar species Rugalucina angela from the northern Indian Ocean and Red Sea, R. vietnamica from South East Asia, and R. munda from northern and north eastern Australia. Lucina concinna from the Red Sea, previously synonymised with P. vietnamica/angela is recognised as a Rugalucina-like species but with a very short anterior adductor scar. Divaricella cypselis from Karachi is similarly now recognised as a distinct species, probably related to Rugalucina but with oblique commarginal sculpture and a short adductor scar. A group of minute Indo-West Pacific lucinids with highly unusual multi-cuspate lateral teeth and previously classified as Pillucina are separated under a new genus Pusillolucinagen. nov., with the description of three new species P. arabica, P. africana, and P. biritika from the Arabian Gulf, Mozambique, and Madagascar. Finally, a new genus, Notocina, is introduced for the small southern Atlantic species, Epicodakia falklandica, shown in molecular analyses to be misplaced at subfamily level and now classified in Lucininae and not Codakiinae with Epicodakia.

NEW RECORD OF ABBREVIATA LEPTOSOMA GERVAIS, 1848 (SPIRURIDA: PHYSALOPTERIDAE) INFECTION IN TWO SPECIES OF LIZARDS IN NORTH AND SOUTH SINAI, EGYPT

Studies on parasitic nematode infection in lizards are rare, and the available literature on their accurate morphological description especially by scanning electron microscopy (SEM) is lacking. Therefore, the aim of the present work isto identify new records of nematode parasites infecting Agamidae lizards, which are widely distributed in North and South Sinai; this entails giving a full morphological picture using light microscopy and SEM. Seventeen samples of Trapelus mutabilisand ten samples of Pseudotrapelus sinaitus (collected from North and South Sinai) were dissected and examined for their nematode parasitic infection. Adult nematodes were collected from the stomach and the upper part of the small intestine, identified, and fully described using light microscopy and SEM. Abbreviata leptosoma was collected for the first time from Egyptian T. mutabilis and P. sinaitus in a prevalence of 11.8% and 30.0% with mean intensity ± standard deviation equals 8.5±7.8 and 4.3±3.2, respectively. A. leptosoma was identified based on the morphological characteristics of both male and female including the cephalic denticulation with 5-8 elements between submedian teeth and lateral tooth, absence of denticulate crest at the dorsal and ventral angles of the mouth, presences of two branched uteri and very unequal dissimilar spicules. The study gives a full SEM description of A. leptosoma.Thus,North and South Sinai are considered as new geographical localities for A. leptosoma infecting Agamidae lizards.

A new Contradens from Laos (Bivalvia: Unionidae: Contradentini)

Here, we describe Contradens novoselovi sp. nov. (Bivalvia: Unionidae), a new freshwater mussel species from the Mekong Basin in Laos. Phylogenetic and morphological analyses reveal that the new taxon is closely related to Contradens comptus (Deshayes &amp; Jullien, 1874) but can be distinguished from it by a smaller size, sub-ovate shell shape, tiny wrinkles near umbo, stronger pseudocardinal and lateral teeth, and fixed nucleotide substitutions. Contradens novoselovi sp. nov. is known only from the type locality in northwestern Laos and may represent a rare endemic species with restricted range.

Effect of home and in-office bleaching systems on the nanomechanical properties of tooth enamel

ObjectivesThe purpose of this in vitro laboratory study was to gauge the nanomechanical properties of the tooth enamel surface using home and in-office bleaching products. MethodsThirty-six extracted lower lateral incisor teeth (sound and without caries, cracks or restorations) were selected. A silicone mould was used to affix the samples in resin after cutting away the roots. Next, the samples were indiscriminately divided into three treatment groups, i.e., 12 teeth in each study group (control, Opalescence Home, and Opalescence Boost), and treated according to their respective group procedures. Surface topography, nano-indentation, and visual analyses were performed. Data were examined statistically using one-way analysis of variance (p < 0.05) ResultsBoth experimental bleaching products enhanced the surface roughness when compared to the samples in the control group. However, the control and Opalescence Boost groups showed insignificant differences. The lowest mean nanohardness (GPa) was observed in the Opalescence Boost group (1.56 GPa ± 0.68 GPa). In contrast, the highest mean nanohardness (GPa) was perceived in the control group (3.53 GPa ± 1.06 GPa). The modulus of elasticity was highly affected using Opalescence Boost (182.63 GPa ± 109.13 GPa) when compared to Control (322.69 GPa ± 168.24 GPa). On visual examination, pronounced roughness was observed in both the Opalescence Home and Opalescence Boost groups. ConclusionBoth teeth whitening products damaged the enamel surface either by roughening the tooth surface or by affecting the nanomechanical properties. Therefore, teeth whitening products may be used, but with great caution.

Anatomical redescription of Cyrenoida floridana (Bivalvia, Cyrenoididae) from the Western Atlantic and its position in the Cyrenoidea

Members of the small bivalve family Cyrenoididae inhabit brackish waters of the eastern and western Atlantic Ocean. Cyrenoida floridana (Dall, 1896) from the western Atlantic is poorly known aside from shell descriptions. A detailed shell and anatomical study of C. floridana is here presented and compared with available data for Cyrenidae and Glauconomidae, two families of closest relationship according to recent phylogenetic studies. The species is characterized by valves externally covered by thin light brown periostracum; muscle scars and pallial line (without sinus) weakly impressed on the internal shell surface; a unique hinge pattern composed of cardinal and lateral teeth joining each other, right hinge with two laterals and two cardinals forming two inverted-V-shaped teeth and left hinge with two cardinals and one lateral forming a horizontal reversed F-shaped tooth; and microtubules inside the shell walls. Anatomically, the species presents unequal adductor muscles; demibranchs fused to each other along their posterior ends; a pair of totally fused, pigmented siphons; two pairs of siphonal retractor muscles; and a stomach with conjoined style sac and intestine, a single typhlosole, and three sorting areas. Evidence of shell parasitism is described.

Differences in the Young modulus and hardness reflect different functions of teeth within the taenioglossan radula of gastropods

One important autapomorphy of molluscs is the radula, which is the anatomical structure used for feeding in most species of Mollusca. As this phylum represents the second species-richest animal group inhabiting very diverse environments, it is not surprising that the morphology of the radula and its teeth is also very diverse between taxa. However, the taenioglossan radulae are remarkable because its tooth types (central, lateral, and marginal teeth) are highly distinct in their morphology within the same radula. There are several hypotheses attempting to explain this tooth diversity by their functional specialisations. Here, for the first time, the functional morphology of taenioglossan radular teeth from one single species was analysed and their material properties (hardness and elasticity modulus) were characterised by nanoindentation. Spekia zonata Bourguignat, 1879 belongs to the Paludomidae inhabiting and feeding on solid substrates in Lake Tanganyika. All tooth types show gradual and significant differences in their stiffness and hardness: from the basis, as the softest and most flexible area, to the stylus and the cusps as the stiffest and hardest areas. The flexibility of the stylus allows the teeth to act as one single feeding organ: the central and lateral teeth can stabilize each other during feeding by the rear teeth providing support to the next row. Tooth types also differ significantly in their stiffness and hardness: the central teeth consist of the hardest and stiffest material, followed by the lateral teeth and finally marginal teeth. This can be explained by different functional loads of teeth: central and lateral ones are used for scratching over the substrate while the marginals serve mainly as brooms collecting food particles.

Management of Anterior Spacing with Peg Lateral by Interdisciplinary Approach : A Case Report

Anterior spacing is a common esthetic problem of patient during dental consultation. The most common etiology include tooth size and arch length discrepancy. Maxillary lateral incisors vary in form more than any other tooth in the mouth except the third molars. Microdontia is a condition where the teeth are smaller than the normal size. Microdontia of maxillary lateral incisor is called as “peg lateral”, that exhibit converging mesial and distal surfaces of crown forming a cone like shape. A carefully documented diagnosis and treatment plan are essential if the clinician is to apply the most effective approach to address the patient’s needs. A patient sometimes requires a multidisciplinary approach to correct the esthetics and to improve the occlusion. This case report describes the management of an adult female patient with a proclined upper anterior teeth, upper anterior spacing, deep bite and peg shaped upper right lateral incisor tooth through orthodontic and restorative treatment approach.

Growling from the gut: co-option of the gastric mill for acoustic communication in ghost crabs.

Animal acoustic communication systems can be built upon co-opted structures that become specialized for sound production or morphological novelties. The ghost crab, Ocypode quadrata, evolved a novel stridulation apparatus on the claws that is used during agonistic interactions, but they also produce a rasping sound without their claw apparatus. We investigated the nature of these sounds and show that O. quadrata adopted a unique and redundant mode of sound production by co-opting the gastric mill (grinding teeth of the foregut). Acoustic characteristics of the sound are consistent with stridulation and are produced by both male and female crabs during aggressive interactions. Laser Doppler vibrometry localized the source of maximum vibration to the gastric region and fluoroscopy showed movement of the gastric mill that coincided with stridulation. The lateral teeth of the gastric mill possess a series of comb-like structures that rub against the median tooth to produce stridulation with dominant frequencies below 2 kHz. This previously undescribed gastric stridulation can be modulated and provide a means of assessment during aggressive interactions, similar to the use of the claw stridulation apparatus. This functional redundancy of stridulation in crabs offers unique insights into the mechanisms of evolution of acoustic communication systems.

Tooth and consequences: Heterodonty and dental replacement in piranhas and pacus (Serrasalmidae).

Tooth replacement in piranhas is unusual: all teeth on one side of the head are lost as a unit, then replaced simultaneously. We used histology and microCT to examine tooth-replacement modes across carnivorous piranhas and their herbivorous pacu cousins (Serrasalmidae) and then mapped replacement patterns onto a molecular phylogeny. Pacu teeth develop and are replaced in a manner like piranhas. For serrasalmids, unilateral tooth replacement is not an "all or nothing" phenomenon; we demonstrate that both sides of the jaws have developing tooth rows within them, albeit with one side more mineralized than the other. All serrasalmids (except one) share unilateral tooth replacement, so this is not an adaptation for carnivory. All serrasalmids have interlocking teeth; piranhas interdigitate lateral tooth cusps with adjacent teeth, forming a singular saw-like blade, whereas lateral cusps in pacus clasp together. For serrasalmids to have an interlocking dentition, their teeth need to develop and erupt at the same time. We propose that interlocking mechanisms prevent tooth loss and ensure continued functionality of the feeding apparatus. Serrasalmid dentitions are ubiquitously heterodont, having incisiform and molariform dentitions reminiscent of mammals. Finally, we propose that simultaneous tooth replacement be considered as a synapomorphy for the family.

Acricotopus indet. morphotype incurvatus: Description and genetics of a new Orthocladiinae (Diptera: Chironomidae) larval morphotype from the Tibetan Plateau.

High mountain ranges such as the Tibetan Plateau with an average altitude above 4500m are topographically complex formations. Elevational gradients, physiographic diversity and climatic heterogeneity have led to highly biodiverse ecosystems in these regions. Mountain ranges can be seen as cradles of evolution and harbour, due to their unique characteristics, a high number of highly adapted species. At the same time these areas are hard to access and therefore taxonomic information is limited. Here we describe a new Acricotopus (Diptera: Chironomidae: Orthocladiinae) larval morphotype occurring in lakes and ponds of differing salinity and water depths located on the Southern and Central Tibetan Plateau. The description is based on larvae and their genetics (ribosomal 18S, 28S and mitochondrial COI sequences) collected from a shallow pond in close proximity to the large saline lake Selin Co. Larvae of Acricotopus indet. morphotype incurvatus are characterized by a mentum with a cluster of lateral teeth, partially folded inwards, a mandible with a toothed lobe in addition to four inner teeth and a sclerotized plate positioned behind the mentum. Up to now, these morphological features have only been found in early instars of other Acricotopus species. The proposed morphotype name is inspired by the peculiar form of the mentum.

Taxonomic revision of the genus Anostomoides (Characiformes: Anostomidae).

A taxonomic revision of Anostomoides is herein presented based on a comprehensive revision of specimens deposited in fish collections and the literature. The present revision proposes that A. laticeps is a junior synonym of A. atrianalis, while A. passionis is a junior synonym of Leporinus nattereri, and the latter is thus transferred to Anostomoides, forming the new combination Anostomoides nattereri. Principal Components Analysis (PCA) showed that examined specimens form two distinct morphotypes, corroborating the validity of both A. atrianalis and A. nattereri. Anostomoides nattereri is distinguished from A. atrianalis by having four branchiostegal rays (vs. three), three pores in infraorbital one (vs. four), 37-39 pored lateral-line scales (vs. 41-44), lower lip with rounded dermal papillae (vs. forming ridges), three dark rounded midlateral blotches (vs. three or four vertically elongated blotches and/or a faded dark longitudinal stripe), dark lines between scale series on posterior half of body on specimens smaller than 150 mm SL (vs. dark lines absent), a greater body depth (27.6-36.2 % vs. 24.5-38.7% of SL) and smaller interorbital distance (34.4-53.8 % vs. 42.6-67.3 % of HL). Anostomoides nattereri is distributed across several tributaries of the Amazon and Orinoco rivers, whereas A. atrianalis is widespread throughout the Amazon, Orinoco, and Essequibo basins. The genus Anostomoides is currently diagnosed based on a combination of non-exclusive characters: upturned or slightly upturned mouth with four premaxillary teeth including symphyseal tooth bicuspid or with blunt cutting edge, remaining teeth slightly tricuspid (with medial cuspid distinctly larger); four dentary teeth, symphyseal tooth with truncate cutting edge (without cusps); second tooth with a single large cusp, and two lateral teeth with three or slightly more small cusps.