Southern Clade Research Articles

Within the forest: a new species of Ctenomys (Rodentia: Ctenomyidae) from northwestern Patagonia

Abstract The genus Ctenomys is represented by 68 species within at least 9 species groups. In Patagonia, there are 11 described species of Ctenomys in 3 phylogenetic species groups: (1) the sociabilis group; (2) the magellanicus group; and (3) the mendocinus group—added to this is C. maulinus, which is not clearly related to any species group. The magellanicus group is the most representative of Patagonia and includes 6 species, several unnamed forms, and has a widespread distribution from Río Negro and Neuquén provinces in the north of Patagonia to Tierra del Fuego province to the south. The magellanicus group is a highly supported clade and comprises 3 geographically defined lineages: the bidaui clade (northern clade) composed of C. bidaui, C. pulcer, and several undescribed forms; the polytypic haigi clade (central clade) comprising C. haigi, C. contrerasi, C. thalesi, C. sericeus, and Ctenomys cf. C. lentulus (sensu Teta and D’Elía 2020); and the monotypic magellanicus clade (southern clade) consisting of haplotypes assigned to C. magellanicus (including C. colburni). Ctenomys magellanicus (Magellanic Tuco-tuco) is widely distributed from southern Santa Cruz province in Argentina and central Aysén in Chile to Isla Grande de Tierra del Fuego in Argentina and Chile. Based on mitochondrial Cytochrome b DNA sequences and morphological assessment (qualitative and quantitative), we describe a new species of Ctenomys related to C. magellanicus from northwestern Chubut Province, Argentina. We provide anatomical comparisons between the new species and other species of Ctenomys from Patagonia, especially C. magellanicus, C. haigi, and C. plebiscitum. In addition, we recognize 2 groupings within C. magellanicus because of their morphometric differences, and report new localities for C. haigi and C. plebiscitum.

Skull morphology analysis suggests the extinct Cape lion, Panthera leo melanochaita (Smith, 1842), is not distinctive

The lion (Panthera leo) was extirpated from the Cape region of South Africa during the mid-nineteenth century. Whilst historically classified as a distinct subspecies known as the Cape lion (P. l. melanochaita), recent molecular studies challenge the distinctiveness of this population, suggesting that it represents the southernmost population of the species' Southern Clade. The Cape lion is often cited as having a distinctive skull morphology, which has justified its subspecific classification, but only a limited number of specimens have been available for examination, so that the Cape lion’s skull morphology has not been satisfactorily understood. In this study we collected morphometric data from a greatly enlarged sample of 22 Cape lion skulls, including 12 adults, constituting the largest sample size analysed for this possible subspecies. The results suggest that (1) morphological characteristics of the skull previously thought to distinguish the Cape lion are not diagnostic, and (2) nor is the skull morphology of male and female Cape lions distinct from that of males and females of other southern African lions. Our results independently support those based on molecular investigations, which suggest that the Cape lion was not distinct from other lions within the Southern Clade.

Forty years later: a new Andean stream treefrog of the genus Hyloscirtus (Anura: Hylidae) from Ecuador, with comments on arm hypertrophy in the H. larinopygion group

We present the description of a novel treefrog species inhabiting the Andean streams in southeastern Ecuador that has been erroneously identified as Hyloscirtus lindae for four decades. The new species is closely related to H. tapichalaca and is part of the southern clade of the H. larinopygion group, which comprises five species confined to the southeastern Andes of Ecuador to the northeastern Andes of Peru. It is diagnosed from its close relatives by a unique combination of characteristics, including hypertrophied forelimbs in males, a pronounced, curved, and protruding spine-shaped prepollex, a substantial supracloacal flap, supratympanic fold, digital discs colored in shades of orange-red or bright-red, and the concealed surfaces of limbs displaying a bluish-gray hue and dorsal spicules in males. We briefly explore the implications of this discovery for the evolution of arm morphology in the H. larinopygion group. Our findings underscore the continued importance of periodically reviewing historical specimens, leading to unexpected discoveries; once again confirming the importance of natural history museums and their custodian biological collections.

Habitat quality or quantity? Niche marginality across 21 plants and animals suggests differential responses between highland and lowland species to past climatic changes

Climatic changes can affect species distributions, population abundance, and evolution. Such organismal responses could be determined by the amount and quality of available habitats, which can vary independently. In this study, we assessed changes in habitat quantity and quality independently to generate explicit predictions of the species' responses to climatic changes between Last Glacial Maximum (LGM) and present day. We built ecological niche models for genetic groups within 21 reptile, mammal, and plant taxa from the Baja California peninsula inhabiting lowland or highland environments. Significant niche divergence was detected for all clades within species, along with significant differences in the niche breadth and area of distribution between northern and southern clades. We quantified habitat quantity from the distribution models, and most clades showed a reduction in distribution area towards LGM. Further, niche marginality (used as a measure of habitat quality) was higher during LGM for most clades, except for northern highland species. Our results suggest that changes in habitat quantity and quality can affect organismal responses independently. This allows the prediction of genomic signatures associated with changes in effective population size and selection pressure that could be explicitly tested from our models.

Genomic evaluation of mud sunfish in the atlantic slope drainage

Mud Sunfish (Acantharchus pomotis, Baird), a cryptic species native to the Atlantic and Gulf slope drainages of North America, have experienced a documented reduction in their geographic range. Atlantic Slope populations of Mud Sunfish were evaluated to determine the population structure, assess genetic diversity, and to identify presence of evolutionary significant units (ESU) in order to develop fundamental understandings of its occurrence. Tissue samples were collected from across the Atlantic Slope for genomic comparison. Restriction site Associated DNA Sequencing (RAD-Seq) was performed on 95 individuals from 14 populations. Mantel test provided evidence of a correlation between genetic and geographical distances, suggesting a pattern of isolation-by-distance. Differences among populations of Mud Sunfish largely occur along a north-south latitudinal gradient. Bayesian clustering of putatively outlier SNP loci, suggests that regional adaptive pressure is occurring. Despite a large geographic distance and significant differences between the majority of the populations of Mud Sunfish, Bayesian clustering analysis suggests that two unresolved clades are persisting within the Atlantic Slope Drainage: a northern clade of Mud Sunfish ranging from New Jersey to North Carolina and a southern clade ranging from South Carolina to Florida. A population of Mud Sunfish in Florida appears distinct from all others in the Atlantic Coastal plain and likely represents a distinct management unit.

Vicariance and cryptic diversity revealed by molecular phylogenetic analyses of estuarine Gammarus species (Crustacea: Amphipoda) due to formation of the Labrador Current

The metapopulation of the estuarine species Gammarus tigrinus along the east coast of the United States has been hypothesised to represent two cryptic species divided biogeographically off the coast of North Carolina, USA. This divergence has been attributed to a strong temperature gradient created by the formation of the cold Labrador Current c. 3.0 million years ago. In addition, the northern phylogeographic clade of G. tigrinus has been demonstrated to be invasive in estuarine habitats across a large portion of northern Europe. Recent collections of G. tigrinus from Florida and Maryland, USA, allow for new approaches to test this hypothesis. Using the nuclear 18S and 28S rRNA, and mitochondrial 16S rRNA and cytochrome c oxidase subunit I genes, species delimitation models provide support that the genetic divergence of the northern and southern clades is equivalent to species level. In addition, molecular clock data demonstrate that this phylogeographic divergence coincides with the formation of the Labrador Current. Furthermore, the collections of G. daiberi from Florida, a species with biogeographical and ecological characteristics similar to those of G. tigrinus, provide independent support for the hypothesis. The potential for invasive species to be cryptic highlights the need for accurate identification of taxa to ensure that appropriate biogeographical assessment of potential source populations and mechanisms of dispersal can be made.

Mitogenome-based genetic management of captive Great Hornbill in Thailand: Implications for reintroduction

The Great Hornbill (Buceros bicornis) is globally vulnerable due to high rates of deforestation and hunting and are therefore a target for restoration. Captive breeding programs in Thailand maintain many Great Hornbills, however active genetic management of captive hornbills was not incorporated into the species recovery plan. With Great Hornbill reintroductions planned for northern Thailand in the immediate future, lack of genetic profiles and phylogenetic relationships among potential founders might hamper population recovery efforts. We assessed the mitochondrial genome (mitogenome) diversity, genetic structure, and evolutionary history of 97 captive Great Hornbills across five zoos in Thailand. Among the 97 samples, we found 21 haplotypes with a haplotype and nucleotide diversity of h = 0.81336 ± 0.021 and pi = 0.00108 ± 0.00040, respectively. The maintenance of mitogenome diversity and no genetic differentiation between five captive populations (FST = 0.00000–0.09723, p > 0.05) might be a result of frequent founder exchange among facilities. Phylogenetic analysis revealed the existence of a southern clade BBITH13, indicating a genetically distinct southern population. To protect these genetic lineages and maintain adaptability of hornbills that have been reintroduced, breeding facilities that contain unique haplotypes should be given high priority in breeding plans. Our data support the evolutionary value of the captive hornbill population in Thailand and highlight the significance of incorporating active genetic management strategies into the species recovery plan for Great Hornbills.

Demographic complexity within walnut species provides insights into the heterogeneity of geological and climatic fluctuations in East Asia

AbstractEast Asia constitutes one of the largest and most complex areas of plant diversity globally. This complexity is attributable to the geological history and climatic diversity of East Asia. However, controversy persists over the biogeographical hypotheses and different studies on this topic. The demographical complexity of temperate deciduous woody plants and heterogeneity of geological and climatic fluctuations in East Asia remain poorly understood. We aimed to assemble the chloroplast and nuclear genomes of 360 individuals from five walnut (Juglans) species in East Asia and comprehensively analyze the phylogenetic inference, genetic structure, population demographic, and selection pressure. The results showed that East Asian walnuts could be divided into two major groups, that is, section Juglans/Dioscaryon and sect. Cardiocaryon. Within sect. Cardiocaryon, the samples were categorized into the northern clade and southern clade, both of which were affected by Quaternary glaciation; however, the southern clade was affected to a lesser extent. The population expansion events observed in sect. Cardiocaryon and sect. Dioscaryon since the late Miocene indicated that Neogene climate cooling substantially affected the distribution of Tertiary relict plants in East Asia. Biogeographic analysis results showed that the uplift of the Qinghai–Tibetan Plateau (QTP) might have contributed to the divergence within sect. Dioscaryon. Our findings highlight the heterogeneity of climatic fluctuations in the northern and southern regions of East Asia during the late Neogene and Quaternary periods and suggest that the uplift of QTP could have facilitated the divergence of temperate deciduous woody plants.

Ecological niche modeling shed light on new insights of the speciation processes and historical distribution of Japanese fire-bellied newt Cynops pyrrhogaster (Amphibia: Urodela)

Environmental factors play vital roles in determining the range of organisms and application of selective pressures that drive their evolution. Investigation of how these ecological factors influence the diversification of species has long been a point of interest among ecologists. In this study, we used climate-based ecological niche models to project the suitable distributions of four main clades of Japanese fire-bellied newt Cynops pyrrhogaster at the Last Glacial Maximum (LGM), Mid-Holocene (MH), and the present. Then we tested hypotheses regarding ecological niche diversification and the processes of diversification among these clades. The potential distribution of the Northern clade encompassed the Tohoku and Kanto districts, along with the northeastern Chubu district. The Central clade had a potential distribution across the Chubu and Kinki districts, and northeastern Chugoku district. The range of the Western clade was projected to encompass Kyushu, Shikoku, the southern Kinki region, and western Chugoku. Finally, the projected distribution of the Southern clade was limited to the southern Kyushu district. The lack of equivalent niches among the tested pairs indicated the absence of ecological interchangeability among the clades. The results of a similarity test supported significant parapatric divergence of the Northern and Central clades from the remaining clades. On the other hand, the Western and Southern clades probably underwent divergence through an allopatric process. Our paleomodels suggest that the distribution of C. pyrrhogaster may have been reduced and fragmented along the coastal regions during the LGM. The distribution models for the MH estimated a suitable area larger than for the LGM, but smaller than predicted by the current distribution. Our findings serve as a warning that the potential distributions of species could be significantly influenced by future climate change.

More cryptic diversity among spiny lizards of the Sceloporus torquatus complex discovered through a multilocus approach

Abstract A phylogenetic reassessment of the Sceloporus torquatus species complex is presented using a multilocus approach. Topological conflicts related to a clade belonging to disjunct southern populations of S. madrensis are resolved, confirming the identity of such populations as distinct from the nominal populations of S. madrensis located 175 kilometres to the north. We describe this southern clade as a new species distributed in the Sierra Madre Oriental based on its phylogenetic distinctiveness and a combination of morphological characters and measurements, increasing the number of recognised species in the S. torquatus complex to seven.

Fast satellite DNA evolution in Nothobranchius annual killifishes

Satellite DNA (satDNA) is a rapidly evolving class of tandem repeats, with some monomers being involved in centromere organization and function. To identify repeats associated with (peri)centromeric regions, we investigated satDNA across Southern and Coastal clades of African annual killifishes of the genus Nothobranchius. Molecular cytogenetic and bioinformatic analyses revealed that two previously identified satellites, designated here as NkadSat01-77 and NfurSat01-348, are associated with (peri)centromeres only in one lineage of the Southern clade. NfurSat01-348 was, however, additionally detected outside centromeres in three members of the Coastal clade. We also identified a novel satDNA, NrubSat01-48, associated with (peri)centromeres in N. foerschi, N. guentheri, and N. rubripinnis. Our findings revealed fast turnover of satDNA associated with (peri)centromeres and different trends in their evolution in two clades of the genus Nothobranchius.

Phylogeography, genetic diversity, and intraspecific genetic structure of the black-horned capuchin (Sapajus nigritus).

Recent molecular studies have clarified the overarching taxonomy of capuchin monkeys, but intraspecific genetic diversity remains unexplored for most capuchin species. One example is Sapajus nigritus, the southernmost capuchin monkey, found in Brazil and Argentina; its phenotypic diversity has been recognized as two geographic subspecies, but the intraspecific genetic structure of this taxon is poorly known. Here, we sampled across most of this species' geographic distribution, producing a newly sequenced data set for genetic analyses that included 78 individuals from 14 populations. We investigated the intraspecific diversity, genetic structure, and evolutionary history using three mitochondrial markers. Our results indicated that S. nigritus populations exhibited high levels of genetic structure. We found strong support for two monophyletic clades within this species with a deep phylogenetic split, and clear separation from other related taxa. Vicariance events seem to have played a prevalent role in shaping S. nigritus genetic differentiation. The Paraíba do Sul River may have driven the deep divergence between southern and northern clades, whereas the Tietê River may have had a weaker, more recent effect on the divergence of populations within the southern clade.

Palaeoclimatic niche modelling reveals the phylogeographic history of the South African shrew Myosorex varius and the colonisation route of the genus Myosorex (Mammalia, Soricidae) from East Africa

Myosorex varius is a South African generalist shrew, which has been found to consist of several genetic clades across its range. A northern clade inhabits the more mesic, summer-rainfall areas of grassland and savannah in the east of South Africa. A southern clade occupies areas of fynbos in the south, and can be further divided into a western subclade occupying winter-rainfall areas and an eastern subclade occupying areas with aseasonal rainfall. Non-South-African members of the African genus Myosorex primarily are limited to isolated montane habitats along the East African Rift System. Here, we used palaeoclimatic niche modelling to examine the effects of Pliocene and Pleistocene climate change on the distributions of M. varius, its clades and the genus as a whole. Results indicate that repeated cycles of range expansion during glacial periods and fragmentation during interglacials are responsible for current phylogeographic patterns within M. varius. Based on their close alignment with rainfall zones and lack of genetic mixing despite areas of contact, it is likely that these (sub)clades are locally adapted to their respective areas. Earlier climatic fluctuations allowed the genus to ‘island hop’ south from East Africa along the East African Rift System, expanding in range during cooler periods and retreating to montane refugia during warmer periods. Areas currently occupied by Myosorex species largely correspond with predicted montane refugia that have allowed them to survive previous warm periods.

Phylogeography of the Cow Knob Salamander (Plethodon punctatus Highton): populations on isolated Appalachian mountaintops are disjunct but not divergent

Although many studies have examined how taxa responded to Pleistocene climate fluctuations in the Appalachian Mountains, impacts on high-elevation endemics of Central Appalachia are not yet understood. We use mitochondrial (ND4 & Cytb) and nuclear (GAPD) DNA sequences to investigate the phylogeography of the Cow Knob Salamander (Plethodon punctatus), a woodland species from Central Appalachian highlands thought to have origins in the Pleistocene. Data from 72 tail tips representing 25 sites revealed that the species comprises two geographically cohesive mitochondrial clades with a narrow, putative contact zone on Shenandoah Mountain. Molecular clock estimates indicate the clades diverged in the Middle Pleistocene. The population size of the Southern clade appears to have remained stable for at least 50,000 years. Despite spanning several isolated mountain systems, the Northern clade has exceptionally low genetic diversity, probably due to recent demographic expansion. Palaeodemographic hypothesis testing supported a scenario in which a founder effect characterized the Northern clade as it diverged from the Southern clade. Species distribution models predicted no suitable habitat for the species during the Last Glacial Maximum. Ultimately, Pleistocene glacial climates may have driven the species from the northern half of its current range, with recolonization events by members of the Northern clade as climates warmed. Density dependent processes may now maintain a narrow contact zone between the two clades.

Range-wide phylogenomics of the Great Horned Owl (Bubo virginianus) reveals deep north-south divergence in northern Peru.

The Great Horned Owl (Bubo virginianus) inhabits myriad habitats throughout the Americas and shows complex patterns of individual and geographic morphological variation. The owl family Strigidae is known to follow ecogeographic rules, such as Gloger's rule. Although untested at the species level, these ecogeographic rules may affect B. virginianus plumage coloration and body size. Previous studies have indicated that, despite this species' morphological variability, little genetic differentiation exists across parts of their range. This study uses reduced representation genome-wide nuclear and complete mitochondrial DNA sequence data to assess range-wide relationships among B. virginianus populations and the disputed species status of B. v. magellanicus (Magellanic or Lesser Horned Owl) of the central and southern Andes. We found shallow phylogenetic relationships generally structured latitudinally to the north of the central Andes, and a deep divergence between a southern and northern clade close to the Marañón Valley in the central Andes, a common biogeographic barrier. We identify evidence of gene flow between B. v. magellanicus and other subspecies based on mitonuclear discordance and F-branch statistics. Overall differences in morphology, plumage coloration, voice, and genomic divergence support species status for B. v. magellanicus.

Molecular analysis separates the Atlantic population of Montagu's stellate barnacle into two cryptic species

AbstractThe distribution of the intertidal barnacle Chthamalus montagui spans the West Mediterranean Sea and the Northeast Atlantic shores of Europe and West Africa. Knowledge of the phylogeography of this species has been limited to the Mediterranean and the European shores of the Atlantic. The present study considers the populations of West Europe, but also focuses on the overlooked populations of West Africa. We performed a molecular analysis using two markers: the mitochondrial COI gene and the nuclear rRNA ITS gene. Whereas ITS proved to be non‐informative, COI has demonstrated that the East Atlantic population of C. montagui comprises two genetically distinct clades: a northern clade that ranges from Mauritania to Scotland and a southern clade that comprises the populations from Senegal. These clades are separated by the Cape Verde Front, which stretches west of the upwelling area off Mauritania. We consider these clades as two cryptic species of the nominal species C. montagui.

Preliminary assessment of genetic variation in the Japanese endemic freshwater crab, Geothelphusadehaani, based on mitochondrial DNA sequences.

Geothelphusadehaani, a freshwater crab species endemic to Japan, has the largest distribution range amongst the 19 known species in the country. Due to its low dispersal capability and restricted habitat to freshwater, it serves as an excellent model for understanding gene flow between geographically isolated populations. In this study, we analysed the genetic relationships of 26 G.dehaani populations collected from different locations in the Japanese archipelago using two mitochondrial DNA regions - cytochrome oxidase subunit I (COI) and cytochrome b (cytB). Our results from the analysis of molecular variance (AMOVA) revealed high genetic variation amongst populations and the phylogenetic analysis identified four geographical groups: Clade I - Honshu and Shikoku, Clade II - north-eastern Kyushu, Clade III - southern Kyushu and Clade IV - north-western Kyushu. Notably, Clade IV exhibited the highest genetic distance amongst the observed groupings. These findings highlight the need for further examination of G.dehaani in Kyushu, including morphological and behavioural traits, to better understand the observed diversity within the species in the region.

From southern Africa and beyond: Historical biogeography of a monocotyledonous bulbous geophyte

AbstractAimLow taxon sampling and taxonomic uncertainties still obscure our evolutionary knowledge of many taxa, especially widespread lineages across diverse landscapes. Of particular interest are those lineages inhabiting seasonal and arid landscapes, which showcase unique distributional patterns that hint at fascinating histories. Using the most comprehensive sampling to date of a widespread bulbous monocot, we hypothesize two independent dispersals to Madagascar, and that vicariance due to Miocene‐driven aridification contracted a once‐widespread distribution between Africa and Eurasia.LocationSub‐Saharan Africa, Madagascar, Eurasia.TaxonLedebouriinae (Scilloideae, Asparagaceae).MethodsUsing the Angiosperms353 probe set for 195 taxa (86 ingroup taxa), we perform phylogenetic reconstruction using IQ‐Tree, and we infer age estimates using penalized likelihood as implemented in treePL. Capitalizing on our broad geographic sampling, which includes African, Malagasy and Eurasian taxa, we use ‘BioGeoBEARS’ to reconstruct ancestral ranges and investigate the role of vicariance and dispersal.ResultsThe Ledebouriinae originated within the past c. 30 myr in south‐eastern sub‐Saharan Africa, with the major subclades arising soon thereafter. Although long‐distance dispersal cannot be fully ruled out, we argue that vicariance was the major process responsible for the current distribution of Ledebouria in Eurasia. We recover two distinct Ledebouria groups that overlap in eastern Africa but are divided into mostly northern and southern clades with divergent biogeographical histories, each showing an independent dispersal to Madagascar. A similar north–south split is seen in Drimiopsis. Additionally, we recover a complex biogeographic history in the predominantly sub‐Saharan African Ledebouria clade, with rapid radiation at c. 14 mya.Main ConclusionsThe expansion of seasonal rainfall and aridity in sub‐Saharan Africa, coupled with orogenic activity, may have fostered the diversification of the Ledebouriinae and many subclades. Miocene‐driven aridification may have caused fragmentation of a once widespread distribution that led to their occurrence in Eurasia.

Morphological variation and its correlation with bioclimatic factors in Odorrana graminea sensu stricto

The large green cascade frog (Odorrana graminea sensu stricto) shows significant genetic differentiation in China, forming western, southern, and eastern clades. However, the morphological differentiation among the three clades is unclear, and the influence of bioclimatic factors on morphological variation among clades is unknown. Based on 20 morphological traits of 309 specimens from 28 localities, the present study explored the morphological differentiation and variation among clades and their correlation with bioclimatic factors through the multivariate statistical analysis. The results of the present study showed that O. graminea sensu stricto was divided into western, southern, and eastern morphological groups, and the gene flow between neighboring populations had caused an individual misidentification. With the three-step terrain and population distribution latitude and humidity, the annual mean temperature (Bio1) was significantly different between the southern and eastern–western clades; the maximum temperature of the hottest month (Bio5) was significantly different between the southern and western clades, and the mean temperature of the wettest quarter (Bio8) and the precipitation seasonality (Bio15) were significantly different between the eastern and western–southern clades. The southern clade that was affected by a high temperature had a smaller body size and larger sensory organs, and the eastern clade distributed in highly humid areas had a larger body size and smaller sensory organs. Moreover, the annual mean temperature range (Bio7) was the dominant factor in the morphological variation of O. graminea sensu stricto, and it had significant negative correlations with seven traits of male frogs and four traits of female frogs. The effect of precipitation factors on the morphological differentiation of each clade remained unclear. The local adaptation caused by climatic differences was the main reason for the morphological differentiation among clades. These findings will help us to understand amphibians’ abilities to adapt to environmental variation.

Redescription of Euastacus clydensis Riek, 1969 (Crustacea: Parastacidae), a valid species of spiny crayfish from southern New South Wales, Australia

The Giant Sydney Crayfish (Euastacus spinifer (Heller, 1865)) was thought to have a wide range in New South Wales, Australia, spanning some 600 km north-south. A recent extensive molecular phylogenetic and population genomic analysis of E. spinifer across its geographical range revealed strong population structure corresponding to several major geographically correlated clades, the southernmost clade being the most genetically divergent and clearly a separate species. This southern clade corresponds to the junior synonym E. clydensis Riek, 1969 and is sister to the clade comprising the remaining populations of E. spinifer and Euastacus vesper. We formally remove E. clydensis from the synonymy of E. spinifer, increasing the recognised number of species of Euastacus to 54. Euastacus clydensis is redescribed based on type and other material, and is distinguished from E. spinifer by differences in abdominal spination and the form of the antennal scaphocerite. Euastacus clydensis has a restricted southern New South Wales range in the Shoalhaven and Jervis Bay-Clyde River catchments, from Moss Vale south to the vicinity of Clyde Mountain; much of the known range of E. clydensis was burnt in the 2019-2020 eastern Australian megafires.