Color Pattern Research Articles

Species limits in Wiedomys (Cricetidae: Sigmodontinae) reinforce the South American São Francisco River as a biogeographic barrier

Abstract Red-nosed mice (genus Wiedomys) are restricted to the Brazilian Cerrado and Caatinga biomes, distributed along the São Francisco River (SFR). Until recently, Wiedomys was considered monotypic, but 2 species with poorly defined geographic and morphological limits have been recognized: W. cerradensis and W. pyrrhorhinos. Our study used morphological, phylogenetic, and cytogenetic analyses to review and detail species limits within the genus and test whether the SFR could be associated with divergence between lineages. This integrative approach indicated that the SFR delineates the geographic boundaries between species, with W. pyrrhorhinos on the right bank and W. cerradensis on the left bank. The species are reciprocally monophyletic and diverge in cranial size, nasal morphology, and facial pelage color pattern. Karyotypic differences between and within W. pyrrhorhinos and W. cerradensis were also detected, and new chromosome complements (2n = 62, FN = 96 and 2n = 62, FN = 88, respectively) were found. Divergence time (0.339 to 0.025 Ma) is concordant with the timing of diversification of other co-distributed vertebrate taxa, and close to a younger estimate for the formation of SFR’s recent lower course to the east coast. Therefore, our study considerably expands knowledge of the geographic range of the genus, diagnoses of species, karyotypic variability between and within species, and reinforces the role of SFR as an important vicariant barrier in northeastern Brazil.

MORPHOLOGICAL CHARACTERIZATION OF PIGEON PEA [Cajanus cajan (L.) Millspaugh] ACCESSIONS FOR AGRONOMIC TRAITS IN ASSOSA DISTRICT, NORTHWESTERN ETHIOPIA

<p><strong>Background:</strong> Pigeon pea is a tropical grain legume being cultivated as important pulses for human food, feed and soil fertility improvement. Pigeon pea research in terms of crop improvement is still at a low level in Ethiopia. <strong>Objective: </strong>To estimate the Genetic variability of pigeon pea accessions with respect to important qualitative and quantitative traits and select high yielding grain and promising traits for variety development. <strong>Methodology</strong>: Treatments consisted in twenty two pigeon pea accessions (MPG1, MPG2, MPG3, MPG4, MPG5, MPG6, MPG7, MPG8, MPG9, MPG10, MPG11, MPG12, MPG13, MPG14, MPG15, MPG16, MPG17, MPG18, MPG19, MPG20, MPG21 and MPG22) collected from Assosa area. Treatments were laid out in a Randomized Complete Block Design with three replications. <strong>Results:</strong> Qualitative characteristics recorded for accessions showed different modalities and frequencies at vegetative growth stage with the qualitative traits dominated were semi-spreading growth habit 65 %, leaflet shape with lanceolate 70 %, color about 44 % of the accessions exhibited yellow, seed size where 55 % accounted large sized, seed color pattern: 52% of accessions showed plain, pod color where 56 % genotypes had purple, seed with red dominated was 50 % and 71 % of accessions had totally pigmented pod. With respect to quantitative traits, genotypes accessions MPG11 and MPG15 had relatively higher grain yield (> 4000 kg/ ha) with the highest grain yield recorded for genotype MPG18. <strong>Implications:</strong> The investigation of the present study for morphological evaluation of genotype Pigeon pea exhibited genetic variability among accession. <strong>Conclusion</strong>: Agronomic traits such as plant height, branches per plant, pods per plant, seeds per pod, pod length, pod width, hundred seed weight and grain yield for accessions were exhibited significant differences which suggest high yielding accessions could be directly recommended for production while others could be utilized effectively to develop high yielding varieties through hybridization followed by selection. </p>

Phenotypic characterization of Echinochloa species in California rice

AbstractTwo independent greenhouse experiments were conducted in December 2020 and July 2021 in Davis, CA to characterize Echinochloa crus‐galli (L.) P. Beauv., Echinochloa colona (L.) Link, Echinochloa oryzicola (Vasinger) Vasinger and Echinochloa walteri (Pursh) A. Heller found in California rice systems based on their morphological traits. Phenotypic data was collected on 10 vegetative traits including plant height, number of tillers, flag leaf length, flag leaf width, flag leaf angle, the colour of leaf sheath, leaf blade colour, internode colour, node colour, growth habit and nine reproductive traits including number of days to heading, number of panicles, length of panicle, length of panicle branches, seeds per panicle, panicle weight, seed colour, awn length and awn pattern. High plasticity was observed in all species characterized in both experiments for both vegetative and reproductive traits, indicating potential inter‐specific hybridization. Awn length, days to heading, length of the panicle, length of the panicle branches, plant height, flag leaf angle, and growth habit were significantly higher in the fall experiment for all species indicating photoperiod could play a role in the expression of these traits. Also, high variation was observed for plant height, number of tillers, awn length, panicle weight, seeds/panicle, length of panicle branch, and number of panicles for all species in both experiments. The results from this study indicate morphological diversity currently present in Echinochloa species could contribute to their adaptation to selection pressure imposed by different management tools in California, emphasizing the need for a diversified management approach to effectively control this weed species.

Identification and molecular marker development for peel color gene in melon (Cucumis melo L.)

Peel color is an important appearance quality of melons that greatly affects consumer preferences. In this study, a near-isogenic line NIL-G (dark green peel) was generated from B8 (grey-green peel) and B15 (white peel). The F2 population constructed by crossing NIL-G and B15 was used to study the inheritance pattern of peel color, and bulked-segregant analysis sequencing (BSA-seq) was employed to identify the interval in which the target gene was located. Genetic analysis results showed that the dark green peel trait at maturity is controlled by a dominant gene. BSA-seq and molecular markers were used to localize the candidate gene in a 263.7 kb interval of chromosome 4, which contained the CmAPRR2 gene with known functions. Moreover, allelic sequence analysis revealed four SNP variations of the CmAPRR2 gene in B15, of which SNP.G614331A was located at the junction of the 6th exon and 6th intron. The G-to-A mutation caused alternative splicing of the transcript of CmAPRR2 in B15, generating two transcripts (CmAPRR2-A and CmAPRR2-B) with premature termination codons. Furthermore, the Kompetitive Allele Specific PCR (KASP) marker, APRR2-G/A, was developed based on this SNP and shown to co-segregate with the peel color phenotype in the F2 population. Compared to white-peel B15, the expression level of CmAPRR2 in dark green peel NIL-G was higher at each growth stage. Therefore, CmAPRR2 may be the key gene controlling the fruit color of melons. Overall, this study identified a novel allelic variant of CmAPRR2 that leads to white peel formation in mature melons. The study also provides a theoretical basis for further research on the gene regulatory mechanism of melon peel colors and may promote the future use of molecular marker-assisted selection to modify melon peel colors.

A new species of Philosina Ris, 1917 (Zygoptera) from China

A new species Philosina nigromacula Yu & Jin, 2024 is described from Sichuan, southwest China, with paratypes from Sichuan and Jiangxi, east China. The new species is generally similar to Philosina buchi Ris, 1917 but has a different abdominal color pattern. There is a strange sack-like structure on the end of the male genital ligula in P. buchi and P. nigromacula, which is described and discussed for the first time. The fragmented distribution of Philosina Ris, 1917 is also discussed as well as possible reasons for the origins of the genus. The need for protection of the small number of species contained within the unique genus Philosina is also emphasized.

Leptodactylus sertanejo Giaretta & Costa, 2007, a junior synonym of Leptodactylus jolyi Sazima & Bokermann, 1978 (Amphibia, Anura, Leptodactylidae)

The genus Leptodactylus currently comprises 84 species of predominantly Neotropical lowland frogs. The L. fuscus group is the most species-rich in the genus, including the nominal species L. jolyi and L. sertanejo. In a published comprehensive study, involving a total evidence analysis of molecular and non-molecular traits, the grouping of L. jolyi and L. sertanejo was very poorly supported, denoting indifferentiation, and indicated that both species cannot be reliably distinguished from each other morphologically. We analysed the overall morphology and color pattern of the specimens attributed to L. jolyi and L. sertanejo and verified that they are closely similar or even identical. The Comparative Anatomy Index did not present dissimilarities for any morphometric variable. Submitting the values to the Principal Component Analysis, we confirmed the morphometric similarity for all variables. To evaluate the discrepancy degree, the values obtained were submitted to the adherence test of the χ2 and we found that no significant morphometric differences did exist. The advertisement calls of 17 specimens attributed to L. jolyi and L. sertanejo are composed of a single harmonic note constituted by one to four pulses. There are no bioacoustic dissimilarities among the specimens analyzed. The multivariate canonical analysis did not discriminate differences among the specimens. Consequently, considering the poor molecular differentiation and based on the analysis of morphological and meristic characters and on advertisement calls, the synonymization of Leptodactylus sertanejo with L. jolyi is proposed.

Object color knowledge representation occurs in the macaque brain despite the absence of a developed language system.

Animals guide their behaviors through internal representations of the world in the brain. We aimed to understand how the macaque brain stores such general world knowledge, focusing on object color knowledge. Three functional magnetic resonance imaging (fMRI) experiments were conducted in macaque monkeys: viewing chromatic and achromatic gratings, viewing grayscale images of their familiar fruits and vegetables (e.g., grayscale strawberry), and viewing true- and false-colored objects (e.g., red strawberry and green strawberry). We observed robust object knowledge representations in the color patches, especially the one located around TEO: the activity patterns could classify grayscale pictures of objects based on their memory color and response patterns in these regions could translate between chromatic grating viewing and grayscale object viewing (e.g., red grating-grayscale images of strawberry), such that classifiers trained by viewing chromatic gratings could successfully classify grayscale object images according to their memory colors. Our results showed direct positive evidence of object color memory in macaque monkeys. These results indicate the perceptually grounded knowledge representation as a conservative memory mechanism and open a new avenue to study this particular (semantic) memory representation with macaque models.

Vapor Absorption and Liquefication Triggered Dynamic Color Changes and Pattern Conversions on Photonic Crystal Films for Anticounterfeiting.

The widespread use of counterfeit goods caused significant damage to economy, personal data security, and public health. There is an urgent need to develop innovative anticounterfeiting materials to enhance their performance. Anticounterfeiting labels based on responsive photonic crystals have been widely researched for the inherent difficulty in replicating the delicate structures and structure colors. By integrating various distinct nanoparticles (NPs), it is expected to produce photonic crystal patterns that offer more intricate color effects and improved anticounterfeiting capabilities. In this work, we reported a photonic crystal anticounterfeiting label with dynamic color variations in solvent vapors and pattern conversions upon vapor liquefication by utilizing three different nanoparticles including d-SiO2, h-SiO2, and m-SiO2 NPs as building blocks. This anticounterfeiting label exhibits a wealth of dynamic color changes associated with the absorption time, absorption rate, absorption medium, and microstructure of the nanoparticles, offering diverse visual effects and showcasing interesting anticounterfeiting performances. The dynamic color change or pattern conversion effect of this photonic crystal (PC) pattern is realized through refractive index changes induced by vapor absorption or solvent filling, which involves no volume changes and shows exceptional durability for repeated applications. This label shows promising broad applications in anticounterfeiting areas.

The Relevance of Flash Coloration Against Avian Predation in a Morpho Butterfly: A Field Experiment in a Tropical Rainforest

ABSTRACTThe flash coloration hypothesis postulates that otherwise cryptically colored animals suddenly displaying conspicuous colors during movement confuse predators, reducing capture. Morpho helenor butterflies have contrasting colors on dorsal (iridescent blue) and ventral (brown) wing surfaces, resulting in sequential blue “flashes” during flight. We tested whether this flashing pattern reduces avian predation on M. helenor in Atlantic rainforest by changing the flashing effect in three experiments. In Experiment 1, we added a blue band to the ventral wing. In Experiment 2, we covered the dorsal wing's blue band with a brown band. Control groups in each experiment were painted such that wing color patterns remained unaltered. Survivorship was evaluated through mark‐recapture censuses and beak marks on the wings. Results show that survivorship of treated butterflies in Experiment 1 decrease markedly compared to unaltered control individuals, while survivorship of treated butterflies in Experiment 2 did not differ compared to control individuals. In Experiment 3, we detected scant predation on treated (blue band added to ventral wing) and control butterflies (brown band added to ventral wing) on the forest floor (wings closed), corroborating that flash coloration is an important protective mechanism during flight. Our field experiments provide the first evidence, to our knowledge, that flash coloration in bright blue Morpho butterflies is an effective defense mechanism against avian predators in a tropical rainforest.

Reallocation of the magnificent catshark Proscyllium magnificum Last & Vongpanich, 2004 to the genus Ctenacis Compagno, 1973 (Carcharhiniformes: Proscylliidae).

The magnificent catshark Proscyllium magnificum was described in 2004 based off five specimens collected in the Andaman Sea off Myanmar. It was originally allocated to the genus Proscyllium, but recent molecular analyses suggested it was more closely related to the harlequin catshark Ctenacis fehlmanni from the western Indian Ocean. This study incorporated meristics and external and internal morphology, together with molecular data to reclassify the magnificent catshark as Ctenacis magnificum and provides revised diagnoses for the genera Ctenacis and Proscyllium. Ctenacis consists of two allopatric Indian Ocean species, while Proscyllium is monotypic genus confined to the northwest Pacific. The revised Ctenacis can be distinguished from Proscyllium in having a broader and longer head (head length 21%-23% vs. 16%-18% of total length), distance between pectoral and pelvic bases shorter than head length (vs. greater than head length), more teeth (upper jaw with 80-86 vs. 46-62 tooth files), and a complex colour pattern of dark reddish-brown blotches and saddles (vs. colour pattern of small black spots). A revised key to the genera of proscylliids and species of Ctenacis is provided.

A new species of the mantidfly genus Euclimacia from Vietnam (Neuroptera, Mantispidae)

A new species of the family Mantispidae (Neuroptera) from Vietnam is described. Euclimacia radioquaesentissp. nov. shows a unique colour pattern, which is distinctive within the genus. The colouration and morphology of both sexes of the new species are described in detail and illustrated. The naming of the new species is linked to a popular citizen-science event in choosing the name for this species (and three other species from different undescribed species by taxonomists of the Museum für Naturkunde Berlin).

A new insular species of Gehyra (Squamata: Gekkonidae) from Papua New Guinea closely related to Gehyra oceanica

The wide-ranging gecko Gehyra oceanica occupies numerous islands across much of the Pacific Ocean basin. Previous work has identified six divergent genetic lineages within lizards assigned to this species. During an expedition to islands off of northern New Guinea we collected lizards of this complex on Crown Island that differ from all other known Gehyra in being sexually dimorphic in colour pattern. We find this population to also be genetically divergent to the other lineages previously identified, as we do with another lineage of populations from nearby islands. Given the unique colour pattern of the Crown Island population, combined with its divergent range of precloacal-femoral pores in males and its phylogenetic uniqueness from other members of this complex, we describe this population as a new species, Gehyra corona sp. nov. currently known only from Crown Island, Papua New Guinea. The discovery of this new species and an additional divergent genetic lineage from within the G. oceanica complex highlights the need for further taxonomic revision of that species complex. It seems likely that the new species we identify will prove endemic to Crown Island, but additional islands from around the Bismarck Sea need survey to establish its full range. Given the undisturbed habitat on most of Crown Island and the low human population there, we suggest that this species’ IUCN Red List conservation status be Least Concern. http://zoobank.org/urn:lsid:zoobank.org:pub:299432A3-6AC1-408D-9CCD-ECCB054A78FF

Hidden in red: evidence for and against red camouflage in a jumping spider (Saitis barbipes)

Investigating the conspicuousness of animal color patterns to different observers is crucial for understanding their function. This study examines the peculiar case of a jumping spider (Saitis barbipes) whose males display red and black ornaments during courtship despite an apparent inability to distinguish these colors. We propose that, through predator eyes, red may actually be a better match than black to the spiders’ leaf litter background, and that the black fringe of hairs surrounding red ornaments may blur with red at natural predator acuities and viewing distances to produce a background-matching desaturated red. In a field experiment, we test whether red ornaments reduce predation relative to red ornaments painted black, and find that, unexpectedly, spiders with red ornaments are more heavily predated upon. Having established birds as the spiders’ primary predators, we image the spiders in their natural habitat using an avian-vision camera. We find their red coloration to have similar color contrast, but lower achromatic contrast, with the background than black coloration. We also find that red and black elements blur together at typical avian acuities and viewing distances to produce lower chromatic and achromatic contrasts with the background than would be seen by animals with higher acuities and/or closer viewing distances. Interestingly, red ornaments appear orange or yellow when viewed obliquely, which reduces their achromatic, but not chromatic, contrast with the background. Our imaging results provide support for our hypothesis that red is camouflaging, whereas the results of our predation experiment do not. Any functional significance of the spiders’ red coloration therefore remains unresolved.

Polymerization-induced ultrafast and massive growth of colloidal photonic crystals on hydrogel surface

Structural color materials based on colloidal photonic crystals (CPCs) have been extensively investigated since they can be prepared efficiently. Commonly, photonic hydrogels are prepared by a polymerizing pre-gel solution, in which colloids are self-assembled by passive methods. Except for magnetic colloids, the process of forming colloidal photonic crystals in a pre-gel solution requires hours to days, and it is almost impossible to assemble the colloids directly in hydrogels. Here, we present a mild strategy to prepare hydrogels with surface structural color, ordered colloidal arrays are formed at the air-hydrogel interface actively during the polymerization process, and bright structural color forms in minutes on a large scale. Polymer exclusion is the key driving force for the assembly of the colloids, other factors, such as evaporation flux, can also promote the colloids to assemble. Significantly, heterogeneous structural color patterns can be produced easily by exposing the hydrogel surface to air sequentially using a mask during the polymerization process. The simple and fast method provides a general route for preparing structural colored surfaces, which may be suitable for various applications.

On the aquatic phenology of sympatric crested and marbled newts (genus Triturus)

Abstract The large-bodied newts Triturus cristatus and T. marmoratus possess ranges that overlap in western France where they frequently share breeding ponds. I test the hypothesis that the aquatic phenology differs between them, as associated with a more aquatic and terrestrial life style respectively. Total adult population sizes were determined in spring in 13 experiments by the capture-mark-recapture methodology, followed by equivalent experiments in summer. Population sizes dropped by an order of magnitude on average whereas species frequencies changed in favour of T. cristatus, suggesting that T. marmoratus leaves the breeding site earlier than T. cristatus. Interspecies hybrids behaved like T. marmoratus. Descriptions are provided of other features (in ecology, morphology, demography, and colouration pattern) that support the different, aquatic versus terrestrial life styles of T. cristatus and T. marmoratus.

The nomenclatural status of “Anoplophallus maculatus” Cope, 1895, its consequences on the systematics of Lycodon subcinctus auctorum, and the description of a new species (Squamata: Colubridae)

The Malayan banded wolf snake, Lycodon subcinctus (F. Boie, 1827) has a complicated taxonomic and nomenclatural history. For almost a century, the combination Anoplophallus maculatus Cope, 1895 has been applied to populations of L. subcinctus from southern China, with various authors recognizing the taxon maculatus as a subspecies (i.e., Lycodon subcinctus maculatus) or junior synonym. A recent study that proposed the elevation of Chinese L. subcinctus to species rank (as Lycodon “maculatus”) prompted us to re-investigate several nomenclatural issues relevant to Anoplophallus maculatus that have not been fully addressed in the literature. We show that Anoplophallus maculatus was not described as a new species, and actually refers to Megalops maculatus Hallowell, 1861, a Neotropical snake currently known as Leptodeira maculata (Dipsadinae). As a consequence, populations of L. subcinctus recently recognized as Lycodon “maculatus”, have no valid binomen applied to them. To resolve this issue, we provide a new species name for populations of L. subcinctus from China and include a morphological description based on specimens collected across all of mainland Southeast Asia. The new species, Lycodon neomaculatus sp. nov., occurs well outside of southern China, and inhabits Indochina (Cambodia, Laos, Thailand, Vietnam) and eastern Myanmar. Lycodon neomaculatus sp. nov. is distinguished from both L. sealei and L. subcinctus by subtle differences in adult dorsal color pattern and body scalation. The distributions of L. neomaculatus sp. nov. and L. subcinctus sensu stricto appear to be allopatric, and the Isthmus of Kra region in peninsular Thailand may act as a biogeographic filter separating the two species.

Pedigree tracing to determine the origins of the modern Palomino Horse Breeders of America stock-type horse

Registration numbers for the Palomino Horse Breeders of America (PHBA) have risen with the assistance of new registration guidelines. These changes in guidelines allowed for registration of any horse with a palomino body color, including those with unknown pedigrees. While this promoted registry growth, documenting the breed's orgins from those known pedigrees making up the breed's foundation is important with the introduction of unknown pedigrees. This can be accomplished using pedigree tracing, which is of particular value for color registries as the study of coat color patterns is plagued with misunderstandings due to pedigrees with inaccurate color designations. Thus, the objective of this study was to develop an understanding of the historical origins of the modern PHBA stock-type horse through pedigree tracing. Horses (n = 460) were randomly sampled from published entries from 10 years (2012-2022) of the PHBA World Show Championship Horse Show. The All-Breed Database was utilized to obtain documentation of extended pedigrees that included uninterrupted generation-to-generation inheritance patterns of a cream dilution allele-influenced coat color. Pedigrees were traced back to the earliest recorded relative. We observed six foundation sires contributed to the modern PHBA stock-type horse with the majority (58%) tracing back to a sire named Old Fred. Two identified sires, Yellow Jacket (4%) and Cotton Eyed Joe (3%), have conflicts concerning color designation. While these results assist in documenting the breed's origins, genetic testing is required to accurately identify the cream dilution allele within the horses registered to ensure a phenotype-based solely on the cream dilution allele.

Gross, histologic, and ultrastructural features of iridophoromas in Siamese fighting fish (Betta splendens).

Pigment-containing and light-reflecting cell neoplasms, generically termed chromatophoromas, affect fish, reptiles, and amphibians. Chromatophoromas of light-reflecting cells are named iridophoromas. In this study, we aimed to describe the gross, histologic, and ultrastructural findings of 71 cases of iridophoromas in farmed Siamese fighting fish (Betta splendens). Macroscopically, iridophoromas appeared as whitish, gray, or black friable masses or plaques in the fin, trunk/tail, or head of the fish. Forty-five tumors (63%) were malignant and invaded the adjacent skeletal muscle and/or metastasized to other organs, whereas 26 (37%) tumors were restricted only to the skin, but due to the cytologic similarity to the malignant counterpart, we were not able to classify them as malignant or benign. Sixty-five (91%) tumors were classified as iridophoromas, whereas 6 (8%) were diagnosed as mixed chromatophoromas. Despite immunolabeling for PNL-2, melan A, or S-100 failing to demonstrate antigen expression, ultrastructural analysis identified light-reflecting neoplastic cells, unequivocally confirming iridophoromas as the predominant tumor. The high incidence of iridophoromas in Siamese fighting fish from the same breeding facility, coupled with a higher occurrence in royal blue and fancy copper color patterns and in young males, suggests a potential genetic/hereditary factor in the tumorigenesis of these neoplasms.

Earth observation reveals the shifting patterns of China's lake colour driven by climate change and land cover

Water colour has been recognized as one of the most important Essential Climate Variables of the lake ecosystem, as it is directly related to changes in water constituents and almost all of the lake's ecological changes could alter water colour. Given the high retrieval accuracy from existing Earth observation satellite data, water colour, in terms of Forel Ule Index (FUI), can be a realistic indicator to track the long-term changes in the lake ecosystem and further explore the lake response to environmental changes. This paper aims to comprehensively investigate the spatiotemporal variation patterns of FUI in 159 large lakes (≥25 km2) across China during 2000–2022 based on the MODIS data and detect the climatic and anthropogenic driving forces of these changes. The 23 years of MODIS records revealed an overall downward trend of lake FUI across China, indicating the lakes in China shifted to bluer colour during the past two decades. Through driving factor analyses, the complicated interplay among lake colour, lake morphology, regional climate shifts and human interference dynamics was uncovered. In the long term, it was found the pronounced change in lake colour in the western lake zones was primarily attributed to climate warming and humidification, whereas that in the eastern lake zones was mainly related to the alterations in regional land cover during the past two decades. Seasonally, lake basin's air temperature was identified as the main factor impacting the seasonal patterns of lake colour, followed by wind speed and runoff. Spatially, there was high spatial variability in lake colour across China, which was mainly associated with lake elevation and lake basin's precipitation rate, although the factors exhibited considerable divergence across different zones. Based upon the above findings, the implications for lake environment protection and management in different regions of China were further discussed.

Morphological characterization and sexual dimorphism of saw-scaled viper (<em>Echis</em>: viperidae: ophidia) population in Sri Lanka

The Saw-scaled vipers (SSV) of the genus Echis (Viperidae: Ophidia) primarily inhabit tropics. In Sri Lanka, E. carinatus is densely populated in the Northern Province where they account for over 50% of the local snakebites. Although it was initially reported as a unique Sri Lankan subspecies named E. c. sinhaleyus, its existence was later questioned, urging the need for more detail studies. The present study examined morphological characters and sexual dimorphism in 30 specimens (17 males and 13 females) collected from Kilinochchi and Jaffna Districts in the Northern Province, using 12 mensural and 17 meristic traits, updating Deraniyagala’s report of 1951. Results showed that the adult females have longer snout to vent length (SVL) than that of males (280.34±43.32 vs. 240.88±27.03), revealing a positive sexual dimorphism index. Males had a greater TL/SVL ratio (x̄̄=13.89±0.68) than that of females (x̄̄=10.65±085). ANCOVA test retrieved most accurate and an independent significant effect of ‘sex’ on TL while SVL serving as the covariate. Males and females shared consistent meristic characters, except for number of dorsal scales at the lower part of the body, ventral and sub-caudal scales. There were more ventral scales in females (145.54±3.31) than that of males (138.41±4.08), and sub-caudal scales were higher in number in males (28.94±1.85) than that of females (25.85±2.82). Although, there were some colour pattern variations of the specimens, (head pattern and ventral pattern), they were not sex-associated and distributed evenly between males and females. This is the first study to illustrate the detail morphometric characters; mensural traits; meristic traits, and color patterns and to demonstrate the sexual dimorphism in the SSV from Sri Lanka, with noticeable differences in the snoutvent length (SVL), tail length (TL), ventral scales, and sub-caudal scales between male and female.