Color Pattern Research Articles

Morphological variations in the African palm weevil, Rhynchophorus phoenicis (F) (Coleoptera: Curculionidae), in Kenya and Uganda

We investigated morphological differences in the African palm weevil (Rhynchophorus phoenicis) from Kenya (Busia and Kwale) and Uganda using a LEICA EZ4HD stereo microscope and an absolute digimatic caliper. Ten pronotal colour patterns were recorded, of which two (brown with two black spots and black with/without very faint brown bands of variable lengths and positions) are reported for the first time. Pronota of most R. phoenicis from Busia and Uganda were black with/without very faint brown bands of variable lengths and positions. Samples of R. phoenicis from Kwale were dominated by four reddish brown and three black bands, which either ran through the pronotal length or the reddish-brown bands coalesced anteriorly. The following pronotal colour patterns were male-specific: (i) two reddish brown bands, approximately ¾ the pronotal length and coalescing anteriorly, (ii) two reddish brown bands running through the pronotal length but discontinuous towards the posterior end and (iii) a brown pronotum with two black spots. Only the females had (i) two faint reddish brown bands running through the pronotal length, fading posteriorly and (ii) four reddish brown and three black bands, two of the former on either halves coalescing posteriorly. Females had longer snouts and mesocoxal distance, and wider elytra than males. Males possessed a longer profemur than females. Morphometric polymorphism was not linked to the site of sample collection. These findings provide additional diagnostic features and improve sexing of P. phoenicis and open opportunities for further research on the mechanisms for polymorphism in the species.

Identifying Morphs of the Yellow-Legged Hornet (Vespa velutina) and Other Pests of Quarantine Importance with Geometric Morphometrics

We assess the accuracy of geometric morphometrics (GMM) for determining the origin of insects of quarantine importance using the Asian hornet (Vespa velutina Lep.1836) as a case study. This species is highly variable, has an extensive natural distribution, and has been transported to many regions of the world. Forewing landmarks were applied to a large sample of regionally specific color morphs (previously considered “subspecies”) from across the species’ native Asian range. We reconfirm that GMM can statistically distinguish geographic variants independent of the color patterns that have heretofore been used for provenance, but which have been suspected of being unreliable. Almost all morphs in our analyses were statistically different except the centrally located V. v. variana, whose range lies between the continental V. v. auraria Smith, 1852, and V. v. nigrithorax du Buysson, 1905 morphs, and the Malaysian and Indonesian morphs. Even with moderate-sized training samples, discriminant function analysis (DFA) was able to classify geographic morphos with about 90% accuracy (ranging from 60% to 100%). We apply these results to determine the origin of a dead wasp recently intercepted in a mail parcel in Utah. Both DFA and continuous-trait maximum-likelihood clustering suggest that the Utah specimen belongs to the nigrithorax morph, which is native to southern China but now invasive in Europe, Japan, and Korea. These results are also supported by DNA barcode analysis, which groups the Utah individual with nigrithorax populations in South Korea and Japan. The relationship between variation in wing shape and genetic differentiation deserves further study, but molecular data are consistent with the GMM results suggesting that morphometric comparisons may be able to identify and provenance intercepted specimens quickly and inexpensively when molecular sequences and taxonomic specialists are unavailable.

A new species in the Cyrtodactylus intermedius (Squamata: Gekkonidae) group from an isolated limestone karst formation in southwestern Cambodia

The gekkonid lizard Cyrtodactylus intermedius was formerly considered to be a single widespread species in hilly areas across eastern Thailand through southern Vietnam but has recently been partitioned into a complex of 12 nominal species across its range. A population belonging to the C. intermedius group was recently found in an isolated limestone karst block in Kampot Province in southwestern Cambodia, part of which lies within the recently designated Phnom Preah Kuhear Loung Natural Heritage Site. Comparisons of morphometric, meristic, qualitative morphological and color pattern data, as well as a molecular analysis using the mitochondrial ND2 gene, revealed that this population differs from all other named members of the C. intermedius group, and so is described here as a new species. The karst-dwelling C. regicavernicolus sp. nov. was recovered as the sister species to C. laangensis, the most geographically proximate member of the complex and one that is also restricted to a small limestone karst habitat.

Preliminary revision of Alpheus djeddensis Coutière, 1897 species complex, with description of three new species of goby-associated snapping shrimps and taxonomic notes on A. macellarius Chace, 1988 and A. djiboutensis De Man, 1909 (Decapoda: Alpheidae)

The present study deals with several species of goby-associated snapping shrimp in the taxonomically challenging Alpheus brevirostris (Olivier, 1811) species group. Alpheus djeddensis Coutière, 1897 is redescribed based on two specimens from the original type series and material recently collected on the Red Sea coast of Saudi Arabia. Alpheus djiboutensis De Man, 1909, a species without extant type material, is removed from the synonymy of A. djeddensis after a careful analysis of the original description by De Man (1909). A cryptic species, morphologically undistinguishable from A. djeddensis, but with a significant divergence in the COI gene sequence and several consistent differences in colour pattern, is described as A. shukran sp. nov., based on material from Oman and Saudi Arabia. Both A. djeddensis and A. shukran sp. nov. are closely related to A. macellarius Chace, 1988, another potential species complex. Two species previously confused with A. djeddensis or A. djiboutensis in ecological literature and underwater field guides are described as A. tigrinus sp. nov. and A. berumeni sp. nov., based on material from the Red Sea, mainly Saudi Arabia. Each of them has a unique and diagnostic colour pattern and differs from A. djeddensis and A. djiboutensis by a few subtle morphological characters. The identity of the material preliminarily identified as A. cf. tigrinus and A. cf. berumeni from localities outside of the Red Sea needs to be confirmed by molecular analyses. Finally, three specimens from the Red Sea coast of Saudi Arabia are preliminarily identified as A. cf. djiboutensis; their true taxonomic identity, however, remains to be clarified further. All available information on goby associations for the herein treated species is provided.

Machine learning supported ground beef freshness monitoring based on near‐infrared and paper chromogenic array

AbstractMaintaining freshness and quality is crucial in the meat industry, as lipid oxidation can lead to undesirable odors, flavors, and potential health risks. Traditional methods for assessing meat freshness often involve time‐consuming and destructive techniques, highlighting the need for rapid, noninvasive approaches. Recent advancements in spectroscopic and chromogenic sensor array technologies have opened up new avenues for monitoring meat quality parameters, offering the potential for real‐time, accurate, and cost‐effective solutions. As thiobarbituric acid reactive substances (TBARS) value is a classic indicator of meat lipid oxidation, this study investigated the data fusion of near‐infrared spectroscopy (NIR) and paper chromogenic array (PCA) for monitoring ground beef TBARS. A standardized PCA was fabricated by photolithography with nine chemoresponsive dyes. Changes in ground beef volatile organic compounds during storage were captured in the shifts of PCA color patterns. Nippy, an open‐source Python module, was used for automated NIR spectra preprocessing. The optimal preprocessing pipeline was found by 10‐fold cross‐validation in machine learning model development. Among optimized models, partial least square regression showed the best performance in coefficient of determination (R2) of .9477, root mean squared error of prediction of 0.0545 mg malondialdehyde/kg meat, and residual prediction deviation of 4.3717. The promising result of this study indicated the potential for NIR and PCA combinations to monitor TBARS values for ground beef freshness assessment.

The genomics of mimicry: Gene expression throughout development provides insights into convergent and divergent phenotypes in a Müllerian mimicry system.

A common goal in evolutionary biology is to discern the mechanisms that produce the astounding diversity of morphologies seen across the tree of life. Aposematic species, those with a conspicuous phenotype coupled with some form of defence, are excellent models to understand the link between vivid colour pattern variations, the natural selection shaping it, and the underlying genetic mechanisms underpinning this variation. Mimicry systems in which species share a conspicuous phenotype can provide an even better model for understanding the mechanisms of colour production in aposematic species, especially if comimics have divergent evolutionary histories. Here we investigate the genetic mechanisms by which mimicry is produced in poison frogs. We assembled a 6.02-Gbp genome with a contig N50 of 310 Kbp, a scaffold N50 of 390 Kbp and 85% of expected tetrapod genes. We leveraged this genome to conduct gene expression analyses throughout development of four colour morphs of Ranitomeya imitator and two colour morphs from both R. fantastica and R. variabilis which R. imitator mimics. We identified a large number of pigmentation and patterning genes differentially expressed throughout development, many of them related to melanophores/melanin, iridophore development and guanine synthesis. We also identify the pteridine synthesis pathway (including genes such as qdpr and xdh) as a key driver of the variation in colour between morphs of these species, and identify several plausible candidates for colouration in vertebrates (e.g. cd36, ep-cadherin and perlwapin). Finally, we hypothesise that keratin genes (e.g. krt8) are important for producing different structural colours within these frogs.

A New Record of Bufo gargarizans Complex (Bufonidae, Anura) from Truong Son Mounts, Ha Tinh and Ha Giang Provinces, Vietnam Based on Molecular Evidence with a Description of a New Species

Based on a combination of molecular and morphological data, we herein report a new species within the bufonid Bufo gargarizans species complex. This is a widespread species complex with distribution from eastern Russia and the Korean Peninsula to China and the Ryukyu Islands of Japan. Records of this species have been documented in the Guangxi and Yunnan Provinces near the border with Vietnam and, for the first time from Vietnam, in Ha Giang Province. The new record of Bufo cf. gargarizans from Vietnam is from Ha Tinh Province. This species has never been reported from Vietnam so far south, about 550 km south from the previously known locality in Ha Giang Province. The female specimen was found in the Ha Tinh Province, Vu Quang National Park of central Vietnam and two specimens (male and female) were found Ha Giang Province. They are clearly distinguished from B. gargarizans and all the mentioned species by a specific color pattern on the belly and creamy-yellowish throat with large, bright red speckles. Genetic divergences of three Vietnam specimens from Ha Giang and Ha Tinh Provinces in the ND2 gene sequences between the В. sp. nov. and all other congeners ranged from 4.3% (with B. andrewsi) to 7.0% (with B. stejnegeri). We give a description of the morphological characters and coloration of the new record and provide an expanded diagnosis.

Pattern Matters in the Aposematic Colouration of Papilio polytes Butterflies.

Many toxic animals display bright colour patterns to warn predators about their toxicity. This sometimes leads other sympatric palatable organisms to evolve mimetic colour patterns to also evade predation. These mimics, however, are often imperfect, and it is unclear how much their colour patterns can vary away from the model before they become ineffective. In this study, we investigated how predation risk of the palatable Common Mormon butterfly (Papilio polytes) is affected by two alterations of its wing pattern that make it progressively more distinct from its model, the Common Rose (Pachliopta aristolochiae). We deployed butterfly paper models in the field, where all models displayed the same colours but had different patterns. In the first modification from the Wildtype pattern, we exchanged the position of the red and white colour patches but kept the overall pattern constant. In the second modification, we created an eyespot-like shape from the pre-existing pattern elements by moving their positions in the wing, altering the overall wing pattern. Both modifications increased attack risk from predators relative to Wildtype patterns, with the eyespot-like modification having the highest predation risk. Our results show that avian predators can distinguish between all three patterns tested, and that pattern is important in aposematic signals. Predators learn to avoid aposematic colours, not in isolation, but as part of specific patterns.

Research on the Design of Zhuang Brocade Patterns Based on Automatic Pattern Generation

To promote the inheritance of Zhuang brocade culture and the rapid extraction of features and automatic generation of patterns, this paper constructs a feature dataset of Zhuang brocade patterns and proposes an automatic generation technology using relative coordinates and regional content replacement. Firstly, by sorting through a large number of cases, a feature dataset of Zhuang brocade patterns is constructed. For the significant features of Zhuang brocade patterns, intelligent extraction algorithms and processes are used to effectively extract the color matching, patterns, and organizational forms of the patterns into the feature dataset. Secondly, to generate Zhuang brocade patterns quickly, an automatic generation technology based on genotype encoding and regional replacement algorithms is proposed, which encodes these pattern elements into a format that can be interpreted by computer algorithms. Finally, through similarity evaluation, the method’s feasibility for rapid extraction and generation of Zhuang brocade patterns is effectively verified. This method is significant for the inheritance of Zhuang brocade patterns and the development of the intangible cultural heritage industry.

PHÂN BỐ CỦA LOÀI EPINEPHELUS EPISTICTUS (Temminck and Schlegel, 1843) (Perciformes: Epinephelidae) Ở VÙNG VEN BIỂN BẮC TRUNG BỘ, VIỆT NAM

The article provides data on the morphological characteristics and the distribution of the dotted grouper Epinephelus epistictus (Temminck & Schlegel, 1843) in the coastal area of Thanh Hoa province, North Central Vietnam. Five specimens were collected from Minh Loc fishing port during a fish fauna survey on 06 August 2023. Combine with data from previous studies, this paper provides information of the distribution of E. epistictus in Vietnam in a northward expansion direction, thereby demonstrating the widespread distribution of this species. Species identification was confirmed by morphological characteristics and colour patterns on the body.

Culture protocols of the Metallic Shiner for ornamental aquaculture

AbstractObjectiveWhile North American fishes are often overlooked by the ornamental fish industry, there is growing interest in fishes native to the southeastern USA, a hot spot for fish diversity. The Metallic Shiner Pteronotropis metallicus, a small‐bodied leuciscid native to Florida and Georgia, is sometimes available in the ornamental fish trade through wild collection and limited captive production. This species exhibits a distinctive color pattern straddling the lateral line: a dorsal pink to red line, fading to a black to blue stripe. This group of minnows is largely unknown to ornamental aquaculture and lacks defined culture protocols. Our objective was to develop culture protocols for the Metallic Shiner.MethodsFollowing collection of wild broodstock, we used routine culture methods to experimentally determine substrate preference, egg incubation, egg disinfection, larval feeding, and larval development.ResultMetallic Shiner spawning was more successful on yarn mops compared with other media, with average output of >50 embryos per tank per day. Hatching success was similar for static incubators (24%) and upwelling incubators (20%) and was also similar among egg disinfection treatments (iodine, hydrogen peroxide, and formalin). Larval feeding regimes altered survival, with Otohime A1 exhibiting higher survival (44%) over 14 days posthatch (dph) and better growth than other feeding regimes. During the developmental trial with water temperature at a relatively constant 25°C, length increased from 5 mm notochord length (4 dph) to 8.7 mm standard length (45 dph), with significant milestones occurring at 4 dph (swim bladder inflation), 16 dph (flexion), and 23 dph (hypural plate formation).ConclusionThese data provide basic culture information for the Metallic Shiner while also providing a place of reference to begin investigating culture protocols for related species, including species of conservation concern.

Ecological drivers of ultraviolet colour evolution in snakes

Ultraviolet (UV) colour patterns invisible to humans are widespread in nature. However, research bias favouring species with conspicuous colours under sexual selection can limit our assessment of other ecological drivers of UV colour, like interactions between predators and prey. Here we demonstrate widespread UV colouration across Western Hemisphere snakes and find stronger support for a predator defence function than for reproduction. We find that UV colouration has evolved repeatedly in species with ecologies most sensitive to bird predation, with no sexual dichromatism at any life stage. By modelling visual systems of potential predators, we find that snake conspicuousness correlates with UV colouration and predator cone number, providing a plausible mechanism for selection. Our results suggest that UV reflectance should not be assumed absent in “cryptically coloured” animals, as signalling beyond human visual capacities may be a key outcome of species interactions in many taxa for which UV colour is likely underreported.

A national-scale assessment on the spatial and temporal variations in water color for urban lakes in China

Monitoring the variations of lake water quality is essential for urban water security and sustainable eco-environment health. However, it is challenging to investigate the water quality of urban lakes at large scales due to the need for large-amount in situ data with diverse optical properties for developing the remote sensing inversion algorithms. Forel-Ule Index (FUI), a proxy of quantifying water color, whose calculation does not require in situ data of specific properties, can comprehensively reflect water quality conditions. However, the spatial and temporal distribution of water color in Chinese urban lakes is still poorly understood. To fill this research gap, this study investigated the spatial distribution of water color in 523 urban lakes (area > 0.5 km2) in China using the FUI derived from the high-quality Multi-Spectral Instrument (MSI) data onboard Sentinel-2 during the ice-free period (April–October) from 2019 to 2022. The monthly and seasonal variation patterns of water color in urban lakes were also analyzed. Our results show that green domain is the most common color of urban lakes, with about 86 % of urban lakes in China being green, and non-green lakes accounting for only 14 % of the total number of lakes. The monthly variation of FUI in urban lakes across the country and multiple geographic regions is basically the same. The monthly average FUI first increases, then decreases, and then rebounds. We also found that the seasonal variation of water color in most urban lakes in southern and northern China is opposite. This study helps to comprehensively understand the spatial and temporal variation of water color and quality of urban lakes in China, providing key basic information for the protection and governance of urban lakes.

Sediment colour as a marker of syn-depositional and early diagenetic processes in glaciofluvial sediments

The continental red beds, encompassing a broad spectrum of genetic types, can serve as important palaeoclimatological and palaeoenvironmental archives. The origin of sediment colouration is a complex process involving abiotic processes (e.g., breakdown of original and precipitation of newly-formed minerals), which, together with biogenic factors, lead to mobilisation of redox-sensitive elements and precipitation of Fe- and Mn-(oxy)hydroxides. There is still discussion about the interpretation of the continental red beds as palaeoclimatological archives or the colour patterns reflecting ancient redox gradients. The layers coloured in red, yellow or black can be found in the Quaternary glaciofluvial sediments in the Czech Republic. We are using a combination of field study with multi-spectral petrophysical, petrological and geochemical analyses to investigate the mechanism and timing of the origin of coloured coatings in glaciofluvial sediments, and causes of cycling of Fe, Mn, and other redox sensitive elements and isotopes. The results show that both syn-depositional and early diagenetic processes are responsible for the origin of colour patterns in the Quaternary glaciofluvial sediments. The stable molybdenum and iron isotope fractionation is primarily driven by the breakdown of the primary Fe and Mn-bearing silicates and the precipitation of the secondary Fe- and Mn-(oxy)hydroxides, such as goethite and birnessite. These precipitates are the main components of colouring coatings on the detrital grains and are able to bind other redox-sensitive elements, such as Cu, As, Mo, U, and REEs. The textural patterns and geochemistry suggest that the colour features were developed in the time range of decades to several thousand years after the deposition along ancient subsurface redox gradients due to changes in groundwater flow associated with primary lithology, glaciotectonics, and seasonal changes in the active layer of permafrost. The coatings show morphological features (rods, botryoids) and geochemical signatures (e.g., increased P contents) suggesting involvement of microorganisms to their precipitation.

Identification of candidate genes associated with primary feathers of tianfu nonghua ducks based on Genome-wide association studies

The primary feathers of ducks have important economic value in the poultry industry. This study quantified the primary feather phenotype of Nonghua ducks, including the primary feathers' length, area, distribution of black spots, and feather symmetry. And genome-wide association analysis was used to screen candidate genes that affect the primary feather traits. The genome-wide association study (GWAS) results identified the genetic region related to feather length (FL) on chromosome 2. Through Linkage disequilibrium (LD) analysis, candidate regions (chr2: 115,246,393-116,501,448 bp) were identified and were further annotated to 5 genes: MRS2, GPLD1, ALDH5A1, KIAA0319, and ATP9B. Secondly, candidate regions related to feather black spots were identified on chromosome 21. Through LD analysis, the candidate regions (chr21: 163,552-2,183,853 bp) were screened and further annotated to 47 genes. Among them, STK4, CCN5, and YWHAB genes were related to melanin-related pathways or pigment deposition, which may be key genes affecting the distribution of black spots on feathers. In addition, we also screened 125 genes on multiple chromosomes that may be related to feather symmetry. Among them, significant SNPs on chromosome 1 were further identified as candidate regions (chr1: 142,118,209-142,223,605 bp) through LD analysis and annotated into 2 genes, TGFBRAP1 and LOC113839965. These results reported the genetic basis of the primary feather from multiple phenotypes, and offered valuable insights into the genetic basis for the growth and development of duck feathers and feather color pattern.

Does coevolution in refugia drive mimicry in bumble bees? Insights from a South Asian mimicry group.

Müllerian mimicry was proposed to be an example of a coevolved mutualism promoted by population isolation in glacial refugia. This, however, has not been well supported in butterfly models. Here, we use genomic data to test this theory while examining the population genetics behind mimetic diversification in a pair of co-mimetic bumble bees, Bombus breviceps Smith and Bombus trifasciatus Smith. In both lineages, populations were structured by geography but not as much by color pattern, suggesting sharing of color alleles across regions of restricted gene flow and formation of mimicry complexes in the absence of genetic differentiation. Demographic analyses showed mismatches between historical effective population size changes and glacial cycles, and niche modeling revealed only mild habitat retraction during glaciation. Moreover, mimetic subpopulations of the same color form in the two lineages only in some cases exhibit similar population history and genetic divergence. Therefore, the current study supports a more complex history in this comimicry than a simple refugium-coevolution model.

Gene flow throughout the evolutionary history of a colour polymorphic and generalist clownfish.

Even seemingly homogeneous on the surface, the oceans display high environmental heterogeneity across space and time. Indeed, different soft barriers structure the marine environment, which offers an appealing opportunity to study various evolutionary processes such as population differentiation and speciation. Here, we focus on Amphiprion clarkii (Actinopterygii; Perciformes), the most widespread of clownfishes that exhibits the highest colour polymorphism. Clownfishes can only disperse during a short pelagic larval phase before their sedentary adult lifestyle, which might limit connectivity among populations, thus facilitating speciation events. Consequently, the taxonomic status of A. clarkii has been under debate. We used whole-genome resequencing data of 67 A. clarkii specimens spread across the Indian and Pacific Oceans to characterize the species' population structure, demographic history and colour polymorphism. We found that A. clarkii spread from the Indo-Pacific Ocean to the Pacific and Indian Oceans following a stepping-stone dispersal and that gene flow was pervasive throughout its demographic history. Interestingly, colour patterns differed noticeably among the Indonesian populations and the two populations at the extreme of the sampling distribution (i.e. Maldives and New Caledonia), which exhibited more comparable colour patterns despite their geographic and genetic distances. Our study emphasizes how whole-genome studies can uncover the intricate evolutionary past of wide-ranging species with diverse phenotypes, shedding light on the complex nature of the species concept paradigm.

A new rare catfish species from southeastern Brazil provides insights into the origins of similar colour patterns in syntopic, distantly related mountain trichomycterines (Siluriformes, Trichomycteridae)

Colour patterns are diverse in trichomycterine catfishes and are often used to diagnose species. Here, we analyse the first case of adults of two syntopic species of Trichomycterus sharing nearly identical colour patterns: a rare new species of the subgenus Paracambeva and Trichomycterus maculosus, a distantly related species of the subgenus Trichomycterus. Both species are endemic to the upper Rio Paraíba do Sul basin (RPSB), which had a different course until the Tertiary period and is situated within the Southeastern Brazilian Continental Rift, mostly active in the Eocene-Oligocene. A time-calibrated multigene analysis, 3144 bp, supported the new species as sister to Trichomycterus itatiayae, both comprising a lineage with Middle Miocene age, when that colour pattern would have first arisen. The new species is diagnosed by characters from the latero-sensory system and bone morphology. Our results, combined with available biogeographical data, indicated the colour pattern of T. maculosus arising in the Late Pliocene, following the dispersal of its group to the upper RPSB after river course changing. Two hypotheses for the independent origin of the same colour pattern are discussed. First, a case of evolutionary convergence for adaptation to live on a similarly coloured gravel substrate, giving some cryptic advantage against predators. Second, mimetic association through anti-predation features. In the latter case, although trichomycterids lack fin spines to inoculate venom as in other catfishes, the species here studied have a supposed axillary gland above the pectoral fin, just posterior to the opercular odontodes, but with properties and functions still unknown.

A new species of Homidia (Collembola: Entomobridae) from Korea, with notes on its DNA data

A new species, Homidia pseudokoreana sp. nov., from South Korea described based on morphological data and DNA barcodes. This species is morphologically characterized by the body color pattern with a longitudinal dark stripe on medial area of Th. II to Th. III, coxal macrochaetal formula as 3/4+1,3/4+2, and unguis III with three inner teeth. In this study, DNA sequences of mitochondrial cytochrome c oxidase subunit I (COI) gene were used as DNA barcode to distinguish species. It showed distinct differences in genetic distances between Homidia species. DNA barcoding was a useful tool when identifying morphologically closely related species in Homidia.

Two new species of the armored catfish genus Panaqolus (Siluriformes, Loricariidae) from the Ecuadorian Amazon

Currently four described species of genus Panaqolus have been reported from the Amazon River basin in Ecuador: P. albomaculatus (Kanazawa 1958), P. dentex (Günther 1868), P. gnomus (Schaefer & Stewart 1993) and P. nocturnus (Schaefer & Stewart 1993). Revision of specimens deposited at the fish collection of Museo de la Escuela Politécnica Nacional (MEPN), Quito, indicated the presence of two additional species, both new to science: P. orcesi n. sp. and P. pantostiktos n. sp. The new species are similar to each other, and to P. albomaculatus and P. nix Cramer & Rapp Py-Daniel 2015 in having the head, body, and fins covered with light dots. Diagnostic characters comprise differences in color pattern, including size and density of light dots on head, body, and fins; as well as various morphometric characters. Apparently, both new species reach larger sizes than previously described species of Panaqolus. The two new species can be included in the subgenus Panafilus (Lujan et al. 2017); they come from the Tigre and Napo River basins, two isolated tributaries in the western Amazon.