Terrestrial Elapid Research Articles

Whip it into shape: Revision of the Demansia psammophis (Schlegel, 1837) complex (Squamata: Elapidae), with a description of a new species from central Australia.

The genus Demansia Günther is the most diverse genus of Australian terrestrial elapids. A phylogenetic framework for the familiar but problematic taxa D. psammophis and D. reticulata (Gray) has been long overdue to ascertain interspecific relationships and resolve unclear taxonomic issues. Here we present an integrated molecular phylogenetic and morphological analyses to review species delineation, resulting in confirmation that both D. psammophis and D. reticulata are full species and that some populations referred to D. r. cupreiceps Storr are not distinguishable from more typical D. reticulata. We also find the widespread central Australian population (treated by most authors as part of cupreiceps) to be specifically distinct. We redescribe D. psammophis and D. reticulata to clarify morphological and geographical boundaries and describe D. cyanochasma sp. nov. based on a combination of molecular genetic markers, details of colour and pattern, adult total length and a few morphometric attributes. We also designate a lectotype for D. psammophis from the original syntype series and comment on the necessity for further taxonomic refinement of this distinctive group.

Macroevolution in axial morphospace: innovations accompanying the transition to marine environments in elapid snakes.

Sea snakes in the Hydrophis-Microcephalophis clade (Elapidae) show exceptional body shape variation along a continuum from similar forebody and hindbody girths, to dramatically reduced girths of the forebody relative to hindbody. The latter is associated with specializations on burrowing prey. This variation underpins high sympatric diversity and species richness and is not shared by other marine (or terrestrial) snakes. Here, we examined a hypothesis that macroevolutionary changes in axial development contribute to the propensity, at clade level, for body shape change. We quantified variation in the number and size of vertebrae in two body regions (pre- and post-apex of the heart) for approximately 94 terrestrial and marine elapids. We found Hydrophis-Microcephalophis exhibit increased rates of vertebral evolution in the pre- versus post-apex regions compared to all other Australasian elapids. Unlike other marine and terrestrial elapids, axial elongation in Hydrophis-Microcephalophis occurs via the preferential addition of vertebrae pre-heart apex, which is the region that undergoes concomitant shifts in vertebral number and size during transitions along the relative fore- to hindbody girth axis. We suggest that this macroevolutionary developmental change has potentially acted as a key innovation in Hydrophis-Microcephalophis by facilitating novel (especially burrowing) prey specializations that are not shared with other marine snakes.

Demographic analyses of marine and terrestrial snakes (Elapidae) using whole genome sequences.

The question of whether spatial aspects of evolution differ in marine versus terrestrial realms has endured since Ernst Mayr's 1954 essay on marine speciation. Marine systems are often suggested to support larger and more highly connected populations, but quantitative comparisons with terrestrial systems have been lacking. Here, we compared the population histories of marine and terrestrial elapid snakes using the pairwise sequentially Markovian coalescent (PSMC) model to track historical fluctuations in species' effective population sizes (Ne ) from individual whole-genome sequences. To do this we generated a draft genome for the olive sea snake (Aiysurus laevis) and analysed this alongside six published elapid genomes and their sequence reads (marine species Hydrophis curtus, H.melanocephalus and Laticauda laticaudata; terrestrial species Pseudonaja textilis, Naja Naja and Notechis scutatus). Counter to the expectation that marine species should show higher overall Ne and less pronounced fluctuations in Ne , our analyses reveal demographic patterns that are highly variable among species and do not clearly correspond to major ecological divisions. At deeper time intervals, the four marine elapids appear to have experienced relatively stable Ne , while each terrestrial species shows a prominent upturn in Ne starting at ~4 million years ago (Ma) followed by an equally strong decline. However, over the last million years, all seven species show strong and divergent fluctuations. Estimates of Ne in the most recent intervals (~10kya) are lowest in two of four marine species (H.melanocephalus and Laticauda), and do not correspond to contemporary range sizes in marine or terrestrial taxa.

Ecological and historical legacies on global diversity gradients in marine elapid snakes

AbstractGlobal diversity gradients have been extensively investigated for several biological groups. However, little is known whether the diversity drivers of clades that underwent major environmental transition (e.g., from land to sea) are equivalent across these different environmental settings. Here, we ask if the pattern of diversity of marine elapid snakes is determined by factors analogous to those previously found for terrestrial lineages. Through a model selection framework, we compare the effect of factors that represent five ecological and historical hypotheses. We found that both ecological and historical factors play significant roles, but habitat structure, which can be linked to historical climatic changes, was better supported. This result agrees with that previously found for terrestrial elapids, despite the different environmental pressures in terrestrial and marine contexts. Our findings suggest an equivalence of the underlying process of diversity gradient within the same lineage from land and sea, irrespective of the different physiological, spatial and historical constraints.

Population history and genomic admixture of sea snakes of the genus Laticauda in the West Pacific

Speciation in the open ocean has long been studied, but it remains largely elusive what factors promote or inhibit speciation in such an open environment. Marine amniotes, which evolved from terrestrial ancestors, provide valuable opportunities for studying speciation in the ocean because of their evident aquatic origins. Sea snakes are phylogenetically related to terrestrial elapid snakes and consist of two monophyletic groups (Hydrophiini and Laticaudini). These two groups migrated from land to water almost at the same time, but species diversities are remarkably different: there are approx. 60 species in 16 genera described for hydrophiins, whereas only eight species in the genus Laticauda are described for laticaudins. Here, we provide a high-quality reference genome assembly of a laticaudin L. colubrina with a scaffold N50 value of 40 Mbp, and focused on laticaudins to consider why they have seldom speciated. We performed whole-genome shotgun sequencing of several species of laticaudins sampled in their southmost (Vanuatu) and northmost (Ryukyu) habitats. Demographic histories of Vanuatu and Ryukyu populations suggest that populations of broadly distributed major species are geographically structured. Each species is genetically clearly distinguished, but there is a considerable amount of gene flow between two sibling species distributed sympatrically in Vanuatu. In addition, inter-species genomic admixture is ubiquitously observed among laticaudins even between phylogenetically distant species. Broad distribution of major species combined with such genetic mixability might have prevented laticaudins from genetic isolation and speciation.

New Environment, New Invaders-Repeated Horizontal Transfer of LINEs to Sea Snakes.

Although numerous studies have found horizontal transposon transfer (HTT) to be widespread across metazoans, few have focused on HTT in marine ecosystems. To investigate potential recent HTTs into marine species, we searched for novel repetitive elements in sea snakes, a group of elapids which transitioned to a marine habitat at most 18 Ma. Our analysis uncovered repeated HTTs into sea snakes following their marine transition. The seven subfamilies of horizontally transferred LINE retrotransposons we identified in the olive sea snake (Aipysurus laevis) are transcribed, and hence are likely still active and expanding across the genome. A search of 600 metazoan genomes found all seven were absent from other amniotes, including terrestrial elapids, with the most similar LINEs present in fish and marine invertebrates. The one exception was a similar LINE found in sea kraits, a lineage of amphibious elapids which independently transitioned to a marine environment 25 Ma. Our finding of repeated horizontal transfer events into marine snakes greatly expands past findings that the marine environment promotes the transfer of transposons. Transposons are drivers of evolution as sources of genomic sequence and hence genomic novelty. We identified 13 candidate genes for HTT-induced adaptive change based on internal or neighboring HTT LINE insertions. One of these, ADCY4, is of particular interest as a part of the KEGG adaptation pathway “Circadian Entrainment.” This provides evidence of the ecological interactions between species influencing evolution of metazoans not only through specific selection pressures, but also by contributing novel genomic material.

Global, regional, and cladistic patterns of variation in climatic niche breadths in terrestrial elapid snakes.

We obtained geo-referenced occurrence and climatic data from individual localities for 59 species of terrestrial elapid snakes, used phylogenetic generalized least squares regression to investigate spatial and cladistic patterns of variation in climatic niche breadths, and compared patterns within and across regions and clades to see if they parallel or differ from each other. Specifically, we test (1) whether a species’ climatic niche breadth on a given niche axis relates to its position along that axis, and to its climatic niche breadth on another niche axis, and (2) whether variation in niche breadths among species is explained by within-locality variation in climatic conditions or by among-locality variation. We found that: (1) there is an overall global pattern, and patterns in individual regions or clades generally parallel each other and global patterns; (2) species in warmer environments have narrower temperature niche breadths (TNBs); (3) precipitation niche breadth (PNB) and position are positively related; (4) TNB and PNB are not related; and (5) within-locality variation in climatic conditions explains most variation in TNBs, whereas among-locality variation explains most variation in PNBs. Our results are consistent with those reported for lizards of the families Phrynosomatidae and Varanidae, confirm the importance of within-locality niche breadth to species niche breadth, and show a more important role of among-locality niche breadth in affecting species niche breadth in terrestrial elapids than in lizards.

Ancient Diversification of Three-Finger Toxins in Micrurus Coral Snakes.

Coral snakes, most notably the genus Micrurus, are the only terrestrial elapid snakes in the Americas. Elapid venoms are generally known for their potent neurotoxicity which is usually caused by Three-Finger Toxin (3FTx) proteins. These toxins can have a wide array of functions that have been characterized from the venom of other elapids. We examined publicly available sequences from Micrurus 3FTx to show that they belong to 8 monophyletic clades that diverged as deep in the 3FTx phylogenetic tree as the other clades with characterized functions. Functional residues from previously characterized clades of 3FTx are not well conserved in most of the Micrurus toxin clades. We also analyzed the patterns of selection on these toxins and find that they have been diversifying at different rates, with some having undergone extreme diversifying selection. This suggests that Micrurus 3FTx may contain a previously underappreciated functional diversity that has implications for the clinical outcomes of bite victims, the evolution and ecology of the genus, as well as the potential for biodiscovery efforts focusing on these toxins.

Paleoclimatology, Paleogeography, and the Evolution and Distribution of Sea Kraits (Serpentes; Elapidae;Laticauda)

The geographic range of sea kraits encompasses one of the geologically most-complex regions of the world. At its center lies Wallacea (the transition between the terrestrial biotas of the Asian and Australian tectonic plates) and the Indonesian Throughflow (nexus of the equatorial marine biotas of the Indian and Pacific oceans). The aim of this study was to elucidate the role of paleogeography, paleoclimatology, and oceanic currents in the evolution and distribution of sea kraits across these major biogeographic crossroads and beyond. A recent assessment of times of taxonomic divergence was projected against paleogeographic reconstructions to produce a parsimonious, hypothetical model of events critical for the origin, dispersal, and differentiation of this taxon. Times and degree of divergence of taxa suggested by recent morphological and molecular studies are in accord with various climatological and geologic events. The model postulates that the distribution of sea kraits was neither greatly affected by tectonics, other than the approach of the Australian Plate to the Asian one, nor dominated by the historic barriers to dispersal of terrestrial fauna across Wallacea, or by the Indonesian Throughflow. Rather, the model suggests that two major factors—paleogeographic alteration of the configuration of land and sea, and the directions of sea currents, past and present—provide an explanation of how these amphibious snakes (1) originated from a terrestrial Asian elapid ancestor, (2) subsequently generated the venomous Australian land snakes and their derivatives the true sea snakes, and (3) differentiated into the species complexes, species, and infraspecific entities of the genus Laticauda.

Phylogenetic relationships of three representative sea krait species (genus Laticauda; elapidae; serpentes) based on 13 mitochondrial genes

To investigate the phylogenetic relationships of the genus Laticauda to related higher taxa, we compared the sequences of four mitochondrial genes (12S rRNA, 16S rRNA, ND4, Cytb) from three Laticauda species (L. colubrina, L. laticaudata, and L. semifasciata) with those of 55 Asian and Australo-Melanesian elapid species. We also characterized the complete mitogenomes of the three Laticauda species and compared the sequences of 13 mitochondrial genes from Laticauda species with five terrestrial elapid and one viperid species to estimate phylogenetic relationships and divergence times. Our results showed that the genus Laticauda is paraphyletic to terrestrial elapids and diverged from the Asian elapids approximately 16.23 Mya. The mitogenomes of the three Laticauda species commonly encoded 13 proteins, 22 tRNAs, 12S and 16S rRNAs and two control regions and ranged from 17,170 and 17,450 bp in size. The L. colubrina mitogenome was more similar to that of L. laticaudata than that of L. semifasciata. The divergence time among the three Laticauda clades was estimated at 8–10 Mya, and a close phylogenetic relationship between L. colubrina and L. laticaudata was found. Our results contribute to our understanding of the evolutionary history of sea kraits.

Venom proteome of the yellow-lipped sea krait, Laticauda colubrina from Bali: Insights into subvenomic diversity, venom antigenicity and cross-neutralization by antivenom

The venom proteome of Laticauda colubrina (Bali, Indonesia) was elucidated by nano-ESI-LCMS/MS of the venom reverse-phase HPLC fractions. Altogether 31 distinct forms of proteins were identified and clustered into three toxin families: three-finger toxin (3FTX, 66.12% of total venom proteins), phospholipase A2 (PLA2, 33.26%) and cysteine-rich secretory protein (CRiSP, 0.05%). The 3FTX were α-neurotoxins (five long neurotoxins, LNTX, 48.87%; two short neurotoxins, SNTX, 16.94%) and a trace amount of two cytotoxins (CTX, 0.31%). PLA2 were present with a large diversity of homologues (≥20 forms), however none was annotated to the lethal proteoform reported previously. The venom is highly lethal in mice (LD50=0.10μg/g) and this is driven primarily by the SNTX and LNTX (LD50=0.05–0.13μg/g), since the PLA2 proteins were non-lethal up to 2μg/g (20-time the venom LD50). The SNTX and LNTX were effectively cross-neutralized by the heterologous Sea Snake Antivenom (SSAV, Australian product) (potency=0.27mg toxin per ml antivenom, and 0.40mg/ml, respectively), corroborating the cross-neutralization of the whole venom (potency=1.09mg/ml) and its antigenic immunoreactivity toward SSAV. Furthermore, compared with earlier studies, the present work reveals geographical variation of venom composition for L. colubrina which may have implication for the evolution and conservation of the species. Biological significanceLaticauda colubrina (yellow-lipped sea krait) is a widely distributed, semi-aquatic venomous snake species. The venom proteome at the level of protein family is unsophisticated and consistent with its restricted prey selection. Nonetheless, the subproteomic findings revealed geographical variability of the venom for this widely distributed species. In contrast to two previous reports, the results for the Balinese L. colubrina venom showed that LNTX Neurotoxin a and Neurotoxin b were co-existent while the PLA2 lethal subtype (PLA-II) was undetected by means of LCMS/MS and by in vivo assay. This is an observable trait of L. colubrina considered divergent from specimens previously studied for the Philippines and the Solomon Islands. The stark geographical variation might be reflective of trophic adaptation following evolutionary arms race between the snake and the prey (eels) in different localities. The preferred trait would likely propagate and remain significant within the geographical population, since the strong behaviour of site fidelity in the species would have minimized gene flow between distant populations. Meanwhile, the in vivo neutralization study verified that the efficacy of the heterologous Sea Snake Antivenom (Australian product) is attributable to the cross-neutralization of SNTX and LNTX, two principal lethal toxins that made up the bulk of L. colubrina venom proteins. The findings also implied that L. colubrina, though could be evolutionarily more related to the terrestrial elapids, has evolved a much streamlined, neurotoxin- and PLA2-predominated venom arsenal, with major antigenicity shared among the true sea snakes and the Australo-Papuan elapids. The findings enrich our current understanding of the complexity of L. colubrina venom and the neutralizing spectrum of antivenom against the principal toxins from this unique elapid lineage.

Pentastomids of wild snakes in the Australian tropics.

Pentastomids are endoparasites of the respiratory system of vertebrates, maturing primarily in carnivorous reptiles. Adult and larval pentastomids can cause severe pathology resulting in the death of their intermediate and definitive hosts. The study of pentastomids is a neglected field, impaired by risk of zoonoses, difficulties in species identification, and life cycle complexities. We surveyed wild snakes in the tropics of Australia to clarify which host species possess these parasites, and then sought to identify these pentastomids using a combination of morphological and molecular techniques. We detected pentastomid infections in 59% of the 81 snakes surveyed. The ubiquity of pentastomid infections in snakes of the Australian tropics sampled in this study is alarmingly high considering the often-adverse consequences of infection and the recognized zoonotic potential of these parasites. The pentastomids were of the genera Raillietiella and Waddycephalus and infected a range of host taxa, encompassing seven snake species from three snake families. All seven snake species represent new host records for pentastomids of the genera Raillietiella and/or Waddycephalus. The arboreal colubrid Dendrelaphis punctulatus and the terrestrial elapid Demansia vestigiata had particularly high infection prevalences (79% and 100% infected, respectively). Raillietiella orientalis infected 38% of the snakes surveyed, especially frog-eating species, implying a frog intermediate host for this parasite. Raillietiella orientalis was previously known only from Asian snakes and has invaded Australia via an unknown pathway. Our molecular data indicated that five species of Waddycephalus infect 28% of snakes in the surveyed area. Our morphological data indicate that features of pentastomid anatomy previously utilised to identify species of the genus Waddycephalus are unreliable for distinguishing species, highlighting the need for additional taxonomic work on this genus.

Molecular phylogeny and divergence dates for Australasian elapids and sea snakes (hydrophiinae): evidence from seven genes for rapid evolutionary radiations

One of the most prolific radiations of venomous snakes, the Australo-Melanesian Hydrophiinae includes approximately 100 species of Australasian terrestrial elapids plus all approximately 60 species of viviparous sea snakes. Here, we estimate hydrophiine relationships based on a large data set comprising 5800 bp drawn from seven genes (mitochondrial: ND4, cytb, 12S, 16S; nuclear: rag1, cmos, myh). These data were analysed using parsimony, likelihood and Bayesian methods to better resolve hydrophiine phylogeny and provide a timescale for the terrestrial and marine radiations. Among oviparous forms, Cacophis, Furina and Demansia are basal to other Australian elapids (core oxyuranines). The Melanesian Toxicocalamus and Aspidomorphus group with Demansia, indicating multiple dispersal events between New Guinea and Australia. Oxyuranus and Pseudonaja form a robust clade. The small burrowing taxa form two separate clades, one consisting of Vermicella and Neelaps calanotus, and the other including Simoselaps, Brachyurophis and Neelaps bimaculatus. The viviparous terrestrial elapids form three separate groups: Acanthophis, the Rhinoplocephalus group and the Notechis-Hemiaspis group. True sea snakes (Hydrophiini) are robustly united with the Notechis-Hemiaspis group. Many of the retrieved groupings are consistent with previous molecular and morphological analyses, but the polyphyly of the viviparous and burrowing groups, and of Neelaps, are novel results. Bayesian relaxed clock analyses indicate very recent divergences: the approximately 160 species of the core Australian radiation (including sea snakes) arose within the last 10 Myr, with most inter-generic splits dating to between 10 and 6 Ma. The Hydrophis sea snake lineage is an exceptionally rapid radiation, with > 40 species evolving within the last 5 Myr.

Identification and analysis of venom gland-specific genes from the coastal taipan (Oxyuranus scutellatus) and related species.

Australian terrestrial elapid snakes contain amongst the most potently toxic venoms known. However, despite the well-documented clinical effects of snake bite, little research has focussed on individual venom components at the molecular level. To further characterise the components of Australian elapid venoms, a complementary (cDNA) microarray was produced from the venom gland of the coastal taipan (Oxyuranus scutellatus) and subsequently screened for venom gland-specific transcripts. A number of putative toxin genes were identified, including neurotoxins, phospholipases, a pseudechetoxin-like gene, a venom natriuretic peptide and a nerve growth factor together with other genes involved in cellular maintenance. Venom gland-specific components also included a calglandulin-like protein implicated in the secretion of toxins from the gland into the venom. These toxin transcripts were subsequently identified in seven other related snake species, producing a detailed comparative analysis at the cDNA and protein levels. This study represents the most detailed description to date of the cloning and characterisation of different genes associated with envenomation from Australian snakes.

Reproductive trade-offs in the elapid snakes Austrelaps superbus and Austrelaps ramsayi

Reproductive traits and the trade-offs among these traits were examined in two venomous terrestrial elapid snakes, the Australian lowland copperhead, Austrelaps superbus, and the Australian highland copperhead, Austrelaps ramsayi. Sampling was difficult, so gravid females had to be held in captivity for up to several months prior to parturition. Analyses showed that captivity affected the time of parturition and maternal body condition, but it had no apparent effect on offspring traits. The results were corroborated by conducting partial follicular ablations in gravid A. superbus with fully yolked follicles. While these females gave birth earlier than unmanipulated females, offspring size was highly correlated with follicular size at the time of ablation and fell within the size range observed in the other females. This suggests that offspring size is fixed by the time follicles are fully yolked. Among unmanipulated females, reproductive traits were similar in A. superbus and A. ramsayi, but relationships among the traits differed. In the A. superbus sample, the trade-off between litter size and offspring size only became apparent after partial correlations, presumably because spring foraging obscured this relationship. In the A. ramsayi sample, however, the trade-off between litter size and offspring size was very pronounced. At this locality, there was no evidence of spring foraging, and snakes had fully developed follicles before or soon after they emerged from hibernation. This reduces the temporal separation between the times when litter size and offspring size are fixed and may allow greater control over the distribution of resources to offspring as a function of litter size.

Moving in two worlds: aquatic and terrestrial locomotion in sea snakes (Laticauda colubrina, Laticaudidae)

Abstract Yellow-lipped sea kraits (Laticauda colubrina) are amphibious in their habits. We measured their locomotor speeds in water and on land to investigate two topics: (1) to what degree have adaptations to increase swimming speed (paddle-like tail etc.) reduced terrestrial locomotor ability in sea kraits?; and (2) do a sea krait’s sex and body size influence its locomotor ability in these two habitats, as might be expected from the fact that different age and sex classes of sea kraits use the marine and terrestrial environments in different ways? To estimate ancestral states for locomotor performance, we measured speeds of three species of Australian terrestrial elapids that spend part of their time foraging in water. The evolutionary modifications of Laticauda for marine life have enhanced their swimming speeds by about 60%, but decreased their terrestrial locomotor speed by about 80%. Larger snakes moved faster than smaller individuals in absolute terms but were slower in terms of body lengths travelled per second, especially on land. Male sea kraits were faster than females (independent of the body-size effect), especially on land. Prey items in the gut reduced locomotor speeds both on land and in water. Proteroglyphous snakes may offer exceptional opportunities to study phylogenetic shifts in locomotor ability, because (1) they display multiple independent evolutionary shifts from terrestrial to aquatic habits, and (2) one proteroglyph lineage (the laticaudids) displays considerable intraspecific and interspecific diversity in terms of the degree to which they use terrestrial vs. aquatic habitats.

A Phylogenetic Analysis of Bungarus (Elapidae) Based on Morphological Characters

A Phylogenetic Analysis of Bungarus (Elapidae) Based on Morphological Characters

Venom glands and some associated muscles in sea snakes.

The venom glands and related muscles of sea snakes conform in their general structure to those of the terrestrial elapids. The venom gland, however, is smaller in size and the accessory gland is considerably reduced. A similar pattern is found in the Australian elapid Notechis. The musculus compressor glandulae is well developed in the sea snakes and in some species its posterior-medial portion runs uninterruptedly from the origin to the insertion of the muscle. This might be considered as a primitive condition suggesting an early divergence of the sea snakes from an ancestral elapid stock. Three species of sea snakes, Aipysurus eydouxi, Emydocephalus annulatus, and E. ijimae, feed on fish eggs and have very small, but still functioning, venom glands. The reduced accessory gland of the sea snakes is apparently connected with their aquatic environment, as a similar condition is found also in the elapine Boulengerina annulata which lives in large lakes of Central Africa. The similarity in structure of the venom gland between sea snakes and Notechis scutatus may point to a possible phylogenetic relationship between this group of Australian elapids and hydrophiine snakes.

Physical properties of some snake plasma albumins

The albumin-like proteins were purified from the plasma of three terrestrial elapids and two sea snakes. The albumin-like fraction averaged 25% (range: 21-30%) in concentration of the total plasma proteins as determined by densitometer. The physical properties of the albumin-like proteins purified from these snakes were compared. These properties, e.g. electrophoretic mobility, isoelectric point, extinction coefficient, and molecular weight, were shown to be strikingly similar to those of human plasma albumin. The physical properties of the plasma albumins of the snakes studied are similar to one another. This similarity does not explain our previous observation that Naja albumin is considerably remote immunologically from those of other elapids (Mao et al., 1983).

Immunotaxonomic relationships of sea snakes to terrestrial elapids

1. 1. Serum albumins of 7 species of sea snakes and 15 terrestrial elapids representing 5 subfamilies were compared using microcomplement fixation. 2. 2. Albumin data showed that (a) Laticauda is closely related to hydrophiines supporting earlier transferrin data and (b) that sea snakes are closer to Australasian elapids than to elapids on other continents. 3. 3. The grouping of Australasian elapids in subfamily Acathophiinae is supported. Micrurus shows no close affinity to Laticauda, and placing it in subfamily Elapinae is suggested. 4. 4. Naja albumin is either widely divergent from other elapids or its albumin has evolved at a faster rate than that of other elapids. 5. 5. The divergence times for certain snake groups calculated from albumin data are not compatible with the times derived from fossil records.