Cretaceous–Tertiary diversification among select Scolopendrid centipedes of South India

Taxonomic study on the genus Mongoloniscus Verhoeff, 1930 (Isopoda, Agnaridae) from China: morphological and phylogenetic analyses

A combination of morphological traits and DNA data (COI and 28S rRNA partial sequences) was used to study the genus Mongoloniscus Verhoeff, 1930 from China. Four new species are described: M.crenatus Jiang, Li & Huang, sp. nov., M.orientalis Jiang, Li & Huang, sp. nov., M.polyacanthum Jiang, Li & Huang, sp. nov., and M.parvus Jiang, Li & Huang, sp. nov. Following an in-depth examination of the Mongoloniscus species, Lucasioidesvannamei (Arcangeli, 1927), comb. nov. (from Mongoloniscus) is proposed, and M.chevronus Yang & An, 2021, syn. nov. is synonymized with Koreoniscusracovitzai (Arcangeli, 1927). A restrictive criterion for recognizing the genus Mongoloniscus is also provided in the present study.

Genetic diversity varies with species traits and latitude in predatory soil arthropods (Myriapoda: Chilopoda)

Aim

To investigate the drivers of intra-specific genetic diversity in centipedes, a group of ancient predatory soil arthropods.

Location

Asia, Australasia and Europe.

Time Period

Present.

Major Taxa Studied

Centipedes (Class: Chilopoda).

Methods

We assembled a database of 1245 mitochondrial cytochrome c oxidase subunit I sequences representing 128 centipede species from all five orders of Chilopoda. This sequence dataset was used to estimate genetic diversity for centipede species and compare its distribution with estimates from other arthropod groups. We studied the variation in centipede genetic diversity with species traits and biogeography using a beta regression framework, controlling for the effect of shared evolutionary history within a family.

Results

A wide variation in genetic diversity across centipede species (0-0.1713) falls towards the higher end of values among arthropods. Overall, 27.57% of the variation in mitochondrial COI genetic diversity in centipedes was explained by a combination of predictors related to life history and biogeography. Genetic diversity decreased with body size and latitudinal position of sampled localities, was greater in species showing maternal care and increased with geographic distance among conspecifics.

Main Conclusions

Centipedes fall towards the higher end of genetic diversity among arthropods, which may be related to their long evolutionary history and low dispersal ability. In centipedes, the negative association of body size with genetic diversity may be mediated by its influence on local abundance or the influence of ecological strategy on long-term population history. Species with maternal care had higher genetic diversity, which goes against expectations and needs further scrutiny. Hemispheric differences in genetic diversity can be due to historic climatic stability and lower seasonality in the southern hemisphere. Overall, we find that despite the differences in mean genetic diversity among animals, similar processes related to life-history strategy and biogeography are associated with the variation within them.

A new species of Otostigmus (Chilopoda, Scolopendromorpha, Scolopendridae) from China, with remarks on the phylogenetic relationships of Otostigmuspolitus Karsch, 1881

Through a combination of morphological and DNA data, a new scolopendrid centipede from southern and southwestern China was revealed: O.tricarinatussp. nov. The species belong to the politus group but has three sharp tergal keels. Validation of phylogenetic status was performed through molecular analysis of the cytochrome c oxidase subunit I (COI), 16S rRNA, and 28S rRNA sequences from 16 Otostigmus species. Otostigmustricarinatussp. nov. was found to be two populations and varied in the number of spines on the ultimate prefemur, the sutures on a sternite, and a pore-free median longitudinal strip in the pore field. The Yunnan-Guizhou plateau population of O.tricarinatussp. nov. was sister to the clade O.polituspolitus + O.politusyunnanensis + Guangxi population of O.tricarinatussp. nov. with strong support from both BI (bayesian inference) and ML (maximum likelihood) analyses (PP = 1, BS = 97%).

Spatial patterns of phylogenetic diversity and endemism in the Western Ghats, India: A case study using ancient predatory arthropods

The Western Ghats (WG) mountain chain in peninsular India is a global biodiversity hotspot, one in which patterns of phylogenetic diversity and endemism remain to be documented across taxa. We used a well-characterized community of ancient soil predatory arthropods from the WG to understand diversity gradients, identify hotspots of endemism and conservation importance, and highlight poorly studied areas with unique biodiversity. We compiled an occurrence dataset for 19 species of scolopendrid centipedes, which was used to predict areas of habitat suitability using bioclimatic and geomorphological variables in Maxent. We used predicted distributions and a time-calibrated species phylogeny to calculate taxonomic and phylogenetic indices of diversity, endemism, and turnover. We observed a decreasing latitudinal gradient in taxonomic and phylogenetic diversity in the WG, which supports expectations from the latitudinal diversity gradient. The southern WG had the highest phylogenetic diversity and endemism, and was represented by lineages with long branch lengths as observed from relative phylogenetic diversity/endemism. These results indicate the persistence of lineages over evolutionary time in the southern WG and are consistent with predictions from the southern WG refuge hypothesis. The northern WG, despite having low phylogenetic diversity, had high values of phylogenetic endemism represented by distinct lineages as inferred from relative phylogenetic endemism. The distinct endemic lineages in this subregion might be adapted to life in lateritic plateaus characterized by poor soil conditions and high seasonality. Sites across an important biogeographic break, the Palghat Gap, broadly grouped separately in comparisons of species turnover along the WG. The southern WG and Nilgiris, adjoining the Palghat Gap, harbor unique centipede communities, where the causal role of climate or dispersal barriers in shaping diversity remains to be investigated. Our results highlight the need to use phylogeny and distribution data while assessing diversity and endemism patterns in the WG.

Mesozoic origin and 'out-of-India' radiation of ricefishes (Adrianichthyidae)

The Indian subcontinent has an origin geologically different from Eurasia, but many terrestrial animal and plant species on it have congeneric or sister species in other parts of Asia, especially in the Southeast. This faunal and floral similarity between India and Southeast Asia is explained by either of the two biogeographic scenarios, 'into-India' or 'out-of-India'. Phylogenies based on complete mitochondrial genomes and five nuclear genes were undertaken for ricefishes (Adrianichthyidae) to examine which of these two biogeographic scenarios fits better. We found that Oryzias setnai, the only adrianichthyid distributed in and endemic to the Western Ghats, a mountain range running parallel to the western coast of the Indian subcontinent, is sister to all other adrianichthyids from eastern India and Southeast-East Asia. Divergence time estimates and ancestral area reconstructions reveal that this western Indian species diverged in the late Mesozoic during the northward drift of the Indian subcontinent. These findings indicate that adrianichthyids dispersed eastward 'out-of-India' after the collision of the Indian subcontinent with Eurasia, and subsequently diversified in Southeast-East Asia. A review of geographic distributions of 'out-of-India' taxa reveals that they may have largely fuelled or modified the biodiversity of Eurasia.

India's biogeographic history through the eyes of blindsnakes- filling the gaps in the global typhlopoid phylogeny

The Indian subcontinent's unique geological history is reflected in the diverse assemblage of its biota. The blindsnake superfamily Typhlopoidea, with its unique mix of ancient as well as younger lineages in Asia, provides an opportunity to understand the various biotic exchange scenarios proposed for the Indian landmass. In this study, we aim to understand the biogeographic origins of the four genera of typhlopoids found in India and to decipher their times and modes of arrival in the subcontinent. Five nuclear markers were sequenced for 12 samples collected from across India, encompassing all four genera under study. Published sequences of typhlopoid genera were compiled and combined with Indian sequences to generate a global dataset. Phylogenetic relationships were reconstructed using maximum likelihood and Bayesian inference methods. Divergence times were estimated using BEAST 1.8.2. Ancestral geographical ranges were estimated using DEC + J, implemented in BioGeoBEARS. Divergence time estimates suggest that Gerrhopilus is an ancient lineage, and the lineage leading to it was present on the Indian landmass since the last 100 million years. The other three genera are more recent dispersals into India, possibly trans-oceanic. Biogeographic reconstructions suggest an East Gondwanan origin for Typhlopoidea, an African origin for Grypotyphlops and an Asian origin for Indotyphlops and Argyrophis. It appears that India harbours a combination of ancient and more recently dispersed lineages of typhlopoids. The genus Gerrhopilus is of Gondwanan origin that likely dispersed out of India into Southeast Asia. The other genera are intrusive elements that dispersed into India from Africa (Grypotyphlops) and Asia (Indotyphlops and possibly Argyrophis) post break-up of Gondwana. Thus, our study provides further evidence on the ability of blindsnakes to undergo long distance trans-oceanic dispersal. Results also suggest an Asian origin for typhlopoids from Australasia, Philippines and Wallacea.

Into-India or out-of-India? Historical biogeography of the freshwater gastropod genus Pila (Caenogastropoda: Ampullariidae)

The biota of the Indian subcontinent was assembled through multiple associations with various landmasses during a period spanning the Late Cretaceous to the present. It consists of Gondwanan elements that subsequently dispersed ‘out-of-India’ and biota that dispersed ‘into-India’ after the subcontinent collided with Asia. However, the relative contribution of these connections to the current biotic assembly of the subcontinent has been under-explored. Our aim here was to understand the relative importance of these various routes of biotic assembly in India by studying the historical biogeography of the tropical Old World freshwater snail genus Pila. We reconstructed a near-complete phylogeny, based on nuclear and mitochondrial markers, of Ampullariidae including all the described Pila species from India and Ampullariids worldwide. Thereafter, molecular dating and ancestral range estimation analyses were carried out to ascertain the time frame and route of colonization of India by Pila. The results showed that Pila dispersed into India as well as other parts of tropical Asia from Africa after both India and Africa collided with Eurasia. Furthermore, multiple dispersals took place between Southeast Asia and India. These findings corroborate increasing evidence that much of the current Indian assemblage of biota actually dispersed ‘into-India’ after it collided with Asia.

The out-of-India hypothesis: evidence from an ancient centipede genus, Rhysida (Chilopoda: Scolopendromorpha) from the Oriental Region, and systematics of Indian species

The Oriental Region has been a focus of biogeographical research for more than two centuries. We examined systematics and biogeography of the centipede genus Rhysida in this region. A robust species hypothesis for the Indian subcontinental and Southeast Asian Rhysida clade uses molecular, morphological and distribution data. Twelve species are recognized in two monophyletic species complexes, eight belonging to the Rhysida immarginata and four to the Rhysida longipes species complex. They include Rhysida aspinosa, Rhysida crassispina, R. immarginata, R. longipes and seven new species, five of which are formally named in this paper: Rhysida ikhalama, Rhysida konda, Rhysida lewisi, Rhysida pazhuthara and Rhysida sada The nine Rhysida species are documented taxonomically and their morphological variation is reviewed. An integrative systematic approach reveals that diversity of Rhysida in the Indian subcontinent has been underestimated. Both species complexes started to diversify in the Early to Late Cretaceous in the Indian subcontinent. The out-of-India hypothesis is supported in both clades, because Southeast Asian species are nested in Indian subcontinental clades. Historical biogeographical analyses suggest two independent post-collision dispersal events, one in the immarginata clade and another where R. longipes expanded its range into Southeast Asia.

Convergent recruitment of adamalysin-like metalloproteases in the venom of the red bark centipede (Scolopocryptops sexspinosus)

Many venom proteins have presumably been convergently recruited by taxa from diverse venomous lineages. These toxic proteins have characteristics that allow them to remain stable in solution and have a high propensity for toxic effects on prey and/or potential predators. Despite this well-established convergent toxin recruitment, some toxins seem to be lineage specific. To further investigate the toxic proteins found throughout venomous lineages, venom proteomics and venom-gland transcriptomics were performed on two individual red bark centipedes (Scolopocryptops sexspinosus). Combining the protein phenotype with the transcript genotype resulted in the first in-depth venom characterization of S. sexspinosus, including 72 venom components that were identified in both the transcriptome and proteome and 1468 nontoxin transcripts identified in the transcriptome. Ten different toxin families were represented in the venom and venom gland with the majority of the toxins belonging to metalloproteases, CAPS (cysteine-rich secretory protein, antigen 5, and pathogenesis-related 1 proteins), and β-pore-forming toxins. Nine of these toxin families shared a similar proteomic structure to venom proteins previously identified from other centipedes. However, the most highly expressed toxin family, the adamalysin-like metalloproteases, has until now only been observed in the venom of snakes. We confirmed adamalysin-like metalloprotease activity by means of in vivo functional assays. The recruitment of an adamalysin-like metalloprotease into centipede venom represents a striking case of convergent evolution.

Evolutionary biogeography of the centipede genus Ethmostigmus from Peninsular India: testing an ancient vicariance hypothesis for Old World tropical diversity

BACKGROUND

Understanding the relative influence of vicariance and dispersal in shaping Old World tropical biodiversity remains a challenge. We aimed to infer the roles of these alternative biogeographic processes using a species time-tree for the centipede genus Ethmostigmus from the Old World tropics. Additionally, we explored fine-scale biogeographic patterns for an endemic radiation of Ethmostigmus from the peninsular Indian Plate (PIP), an area with complex geological and climatic history.

RESULTS

Divergence time estimates suggest that Ethmostigmus began diversifying in the Late Cretaceous, 99 (± 25) million years ago (Ma), its early biogeographic history shaped by vicariance. Members of Ethmostigmus in PIP form a monophyletic group that underwent endemic radiation in the Late Cretaceous, 72 (± 25) Ma. In contrast, a new species of Ethmostigmus from north-east India formed a clade with African/Australian species. Fine-scale biogeographic analyses in PIP predict that Indian Ethmostigmus had an ancestor in southern-central parts of the Western Ghats. This was followed by four independent dispersal events from the southern-central Western Ghats to the Eastern Ghats, and between different parts of the Western Ghats in the Cenozoic.

CONCLUSIONS

Our results are consistent with Gondwanan break-up driving the early evolutionary history of the genus Ethmostigmus. Multiple dispersal events coinciding with geo-climatic events throughout the Cenozoic shaped diversification in PIP. Ethmostigmus species in PIP are restricted to wet forests and have retained that niche throughout their diversification.

Venom-gland transcriptomics and venom proteomics of the giant Florida blue centipede, Scolopendra viridis

The limited number of centipede venom characterizations have revealed a rich diversity of toxins, and recent work has suggested centipede toxins may be more rapidly diversifying than previously considered. Additionally, many identified challenges in venomics research, including assembly and annotation methods, toxin quantification, and the ability to provide biological or technical replicates, have yet to be addressed in centipede venom characterizations. We performed high-throughput, quantifiable transcriptomic and proteomic methods on two individual Scolopendra viridis centipedes from North Florida. We identified 39 toxins that were proteomically confirmed, and 481 nontoxins that were expressed in the venom gland of S. viridis. The most abundant toxins expressed in the venom of S. viridis belonged to calcium and potassium ion-channel toxins, venom allergens, metalloproteases, and β-pore forming toxins. We compared our results to the previously characterized S. viridis from Morelos, Mexico, and found only five proteomically confirmed toxins in common to both localities, suggesting either extreme toxin divergence within S. viridis, or that these populations may represent entirely different species. By using multiple assembly and annotation methods, we generated a comprehensive and quantitative reference transcriptome and proteome of a Scolopendromorpha centipede species, while overcoming some of the challenges present in venomics research.

Molecular phylogeny and systematics of the centipede genus Ethmostigmus Pocock (Chilopoda : Scolopendromorpha) from peninsular India

Integrative taxonomy assesses the congruence between different lines of evidence for delimiting species, such as morphological, molecular or ecological data. Herein molecular phylogenetics is used to test monophyly and determine the phylogenetic position of the Old World tropical centipede genus Ethmostigmus Pocock, 1898, and to define species boundaries for Ethmostigmus in peninsular India. A phylogeny of the family Scolopendridae based on DNA sequence data for three markers from 427 specimens sampling in all major lineages (144 individuals generated in this study) recovers Ethmostigmus as a monophyletic group, but relationships among the genera in its subfamily Otostigminae are poorly supported. Two species delimitation methods for DNA sequence data and phylogeny are integrated with morphology and geographic data to propose a well-supported species hypothesis for Ethmostigmus on the peninsular Indian plate. Five species of Ethmostigmus are recognised in peninsular India, of which E. coonooranus Chamberlin, 1920 and three new species, namely, E. agasthyamalaiensis, sp. nov., E. sahyadrensis, sp. nov. and E. praveeni, sp. nov., occur in the Western Ghats, a biodiversity hotspot. The lesser-known Eastern Ghats harbour one species, E. tristis (Meinert, 1886), which has been nearly unreported for 130 years. This study highlights the value of an integrative approach to systematics, especially in underexplored, high biodiversity regions and where morphological variation is limited among closely related species.

Systematic revision and phylogenetic reassessment of the centipede genera Rhysida Wood, 1862 and Alluropus Silvestri, 1912 (Chilopoda: Scolopendromorpha) in Southeast Asia, with further discussion of the subfamily Otostigminae

Phylogenetic relationships of two morphologically similar scolopendrid genera, Rhysida Wood, 1862, and Alluropus Silvestri, 1912, were investigated based on broad-scale taxonomic sampling from SE Asia, India and Australia. Morphological revision and molecular phylogenetics using three loci validate seven Rhysida species in SE Asia and Australia: R. lithobioides (Newport, 1845), R. longipes (Newport, 1845), R. immarginata (Porat, 1876), R. nuda (Newport, 1845), R. carinulata (Haase, 1887), R. singaporiensis Verhoeff, 1937 and R. polyacantha Koch, 1985. The nominal SE Asian species R. leviventer Attems, 1953 and R. marginata Attems, 1953 are placed in junior subjective synonymy with R. lithobioides and Alluropus calcaratus (Pocock, 1891), respectively. The monotypic genus Alluropus is redescribed, molecular phylogeny recovering it nesting together with Indo-Australian Rhysida. Taxonomic revision reassigned R. calcarata Pocock, 1891 to Alluropus based on its morphological and molecular similarity to the type, A. demangei Silvestri, 1912, the differences between putative species being sexual variation. Two morphologically distinct allopatric populations of A. calcaratus, comb. nov. (= A. demangei, syn. nov.) were found in the Indochina subregion. Phylogenetic relationships in Otostigminae remain unsettled because clades within several genera lack significant support, although Rhysida consistently falls into two clades that are not each other’s closest relative.

A taxonomic review of the centipede genus Scolopendra Linnaeus, 1758 (Scolopendromorpha, Scolopendridae) in mainland Southeast Asia, with description of a new species from Laos

The centipede genus Scolopendra in mainland Southeast Asia is reviewed taxonomically based on morphological characters, informed by a molecular phylogenetic analysis using sequences from three mitochondrial and nuclear genes (COI, 16S rRNA and 28S rRNA). Eight nominal species of Scolopendra, namely Scolopendra morsitans Linnaeus, 1758, Scolopendra subspinipes Leach, 1816, Scolopendra dehaani Brandt, 1840, Scolopendra multidens Newport, 1844, Scolopendra calcarata Porat, 1876, Scolopendra japonica Koch, 1878, Scolopendra pinguis Pocock, 1891, and Scolopendra dawydoffi Kronmüller, 2012, are redescribed together with some revision of type materials. Geographical variation in each species has been compiled with reference to samples that span their distribution ranges in Southeast Asia and some parts of neighbouring areas such as East Asia, the Indian Ocean, and Africa. Comparative study of traditional taxonomic characters from external morphology provides further information to distinguish some closely related species. Scolopendra cataracta Siriwut, Edgecombe & Panha, sp. n., is described from the southern part of Laos, with additional records in Thailand and Vietnam. The phylogenetic framework for Southeast Asian Scolopendra recognizes Scolopendra calcarata + Scolopendra pinguis, Scolopendra morsitans, and a Scolopendra subspinipes group that unites the other six species as the main clades. Within the Scolopendra subspinipes group, two monophyletic groups can be distinguished by having either slender or short, thick ultimate leg prefemora and different numbers of apical spines on the coxopleuron. Scolopendra arborea Lewis, 1982, is placed in subjective synonymy with Scolopendra dehaani. A survey of external morphology of the genital segments confirms its potential for improving species identification in Scolopendra. Some observations on biology and behaviour are recorded based on field surveys in this area.

Centipede venoms and their components: resources for potential therapeutic applications

Venomous animals have evolved with sophisticated bio-chemical strategies to arrest prey and defend themselves from natural predators. In recent years, peptide toxins from venomous animals have drawn considerable attention from researchers due to their surprising chemical, biochemical, and pharmacological diversity. Similar to other venomous animals, centipedes are one of the crucial venomous arthropods that have been used in traditional medicine for hundreds of years in China. Despite signifying pharmacological importance, very little is known about the active components of centipede venoms. More than 500 peptide sequences have been reported in centipede venomous glands by transcriptome analysis, but only a small number of peptide toxins from centipede has been functionally described. Like other venomous animals such as snakes, scorpions, and spiders, the venom of centipedes could be an excellent source of peptides for developing drugs for treatments as well as bio-insecticides for agrochemical applications. Although centipede venoms are yet to be adequately studied, the venom of centipedes as well as their components described to date, should be compiled to help further research. Therefore, based on previous reports, this review focusses on findings and possible therapeutic applications of centipede venoms as well as their components.

The Centipede Genus Scolopendra in Mainland Southeast Asia: Molecular Phylogenetics, Geometric Morphometrics and External Morphology as Tools for Species Delimitation

Seven Scolopendra species from the Southeast Asian mainland delimited based on standard external morphological characters represent monophyletic groups in phylogenetic trees inferred from concatenated sequences of three gene fragments (cytochrome c oxidase subunit 1, 16S rRNA and 28S rRNA) using Maximum likelihood and Bayesian inference. Geometric morphometric description of shape variation in the cephalic plate, forcipular coxosternite, and tergite of the ultimate leg-bearing segment provides additional criteria for distinguishing species. Colouration patterns in some Scolopendra species show a high degree of fit to phylogenetic trees at the population level. The most densely sampled species, Scolopendra dehaani Brandt, 1840, has three subclades with allopatric distributions in mainland SE Asia. The molecular phylogeny of S. pinguis Pocock, 1891, indicated ontogenetic colour variation among its populations. The taxonomic validation of S. dawydoffi Kronmüller, 2012, S. japonica Koch, 1878, and S. dehaani Brandt, 1840, each a former subspecies of S. subspinipes Leach, 1814 sensu Lewis, 2010, as full species was supported by molecular information and additional morphological data. Species delimitation in these taxonomically challenging animals is facilitated by an integrative approach that draws on both morphology and molecular phylogeny.

Weaponization of a Hormone: Convergent Recruitment of Hyperglycemic Hormone into the Venom of Arthropod Predators

Arthropod venoms consist primarily of peptide toxins that are injected into their prey with devastating consequences. Venom proteins are thought to be recruited from endogenous body proteins and mutated to yield neofunctionalized toxins with remarkable affinity for specific subtypes of ion channels and receptors. However, the evolutionary history of venom peptides remains poorly understood. Here we show that a neuropeptide hormone has been convergently recruited into the venom of spiders and centipedes and evolved into a highly stable toxin through divergent modification of the ancestral gene. High-resolution structures of representative hormone-derived toxins revealed they possess a unique structure and disulfide framework and that the key structural adaptation in weaponization of the ancestral hormone was loss of a C-terminal α helix, an adaptation that occurred independently in spiders and centipedes. Our results raise a new paradigm for toxin evolution and highlight the value of structural information in providing insight into protein evolution.

Centipede venom: recent discoveries and current state of knowledge

Centipedes are among the oldest extant venomous predators on the planet. Armed with a pair of modified, venom-bearing limbs, they are an important group of predatory arthropods and are infamous for their ability to deliver painful stings. Despite this, very little is known about centipede venom and its composition. Advances in analytical tools, however, have recently provided the first detailed insights into the composition and evolution of centipede venoms. This has revealed that centipede venom proteins are highly diverse, with 61 phylogenetically distinct venom protein and peptide families. A number of these have been convergently recruited into the venoms of other animals, providing valuable information on potential underlying causes of the occasionally serious complications arising from human centipede envenomations. However, the majority of venom protein and peptide families bear no resemblance to any characterised protein or peptide family, highlighting the novelty of centipede venoms. This review highlights recent discoveries and summarises the current state of knowledge on the fascinating venom system of centipedes.

First molecular data and the phylogenetic position of the millipede-like centipede Edentistoma octosulcatum Tömösváry, 1882 (Chilopoda: Scolopendromorpha: Scolopendridae)

Edentistoma octosulcatum Tömösváry, 1882, is a rare, superficially millipede-like centipede known only from Borneo and the Philippines. It is unique within the order Scolopendromorpha for its slow gait, robust tergites, and highly modified gizzard and mandible morphology. Not much is known about the biology of the species but it has been speculated to be arboreal with a possibly vegetarian diet. Until now its phylogenetic position within the subfamily Otostigminae has been based only on morphological characters, being variably ranked as a monotypic tribe (Arrhabdotini) or classified with the Southeast Asian genus Sterropristes Attems, 1934. The first molecular data for E. octosulcatum sourced from a newly collected specimen from Sarawak were analysed with and without morphology. Parsimony analysis of 122 morphological characters together with two nuclear and two mitochondrial loci resolves Edentistoma as sister group to three Indo-Australian species of Rhysida, this clade in turn grouping with Ethmostigmus, whereas maximum likelihood and parsimony analyses of the molecular data on their own ally Edentistoma with species of Otostigmus. A position of Edentistoma within Otostigmini (rather than being its sister group as predicted by the Arrhabdotini hypothesis) is consistently retrieved under different analytical conditions, but support values within the subfamily remain low for most nodes. The species exhibits strong pushing behaviour, suggestive of burrowing habits. Evidence against a suggested vegetarian diet is provided by observation of E. octosulcatum feeding on millipedes in the genus Trachelomegalus.

Clawing through evolution: toxin diversification and convergence in the ancient lineage Chilopoda (centipedes)

Despite the staggering diversity of venomous animals, there seems to be remarkable convergence in regard to the types of proteins used as toxin scaffolds. However, our understanding of this fascinating area of evolution has been hampered by the narrow taxonomical range studied, with entire groups of venomous animals remaining almost completely unstudied. One such group is centipedes, class Chilopoda, which emerged about 440 Ma and may represent the oldest terrestrial venomous lineage next to scorpions. Here, we provide the first comprehensive insight into the chilopod "venome" and its evolution, which has revealed novel and convergent toxin recruitments as well as entirely new toxin families among both high- and low molecular weight venom components. The ancient evolutionary history of centipedes is also apparent from the differences between the Scolopendromorpha and Scutigeromorpha venoms, which diverged over 430 Ma, and appear to employ substantially different venom strategies. The presence of a wide range of novel proteins and peptides in centipede venoms highlights these animals as a rich source of novel bioactive molecules. Understanding the evolutionary processes behind these ancient venom systems will not only broaden our understanding of which traits make proteins and peptides amenable to neofunctionalization but it may also aid in directing bioprospecting efforts.

Did southern Western Ghats of peninsular India serve as refugia for its endemic biota during the Cretaceous volcanism?

The Western Ghats (WG) of south India, a global biodiversity hotspot, has experienced complex geological history being part of Gondwana landmass and encountered extensive volcanic activity at the end of Cretaceous epoch. It also has a climatically and topographically heterogeneous landscape. Thus, the WG offer a unique setting to explore the influence of ecological and geological processes on the current diversity and distribution of its biota. To this end, three explicit biogeographical scenarios were hypothesized to evaluate the distribution and diversification of wet evergreen species of the WG – (1) southern WG was a refuge for the wet evergreen species during the Cretaceous volcanism, (2) phylogenetic breaks in the species phylogeny would correspond to geographic breaks (i.e., the Palghat gap) in the WG, and (3) species from each of the biogeographic subdivisions within the WG would form distinct clades. These hypotheses were tested on the centipede genus Digitipes from the WG which is known to be an ancient, endemic, and monophyletic group. The Digitipes molecular phylogeny was subjected to divergence date estimation using Bayesian approach, and ancestral areas were reconstructed using parsimony approach for each node in the phylogeny. Ancestral-area reconstruction suggested 13 independent dispersal events to explain the current distribution of the Digitipes species in the WG. Among these 13 dispersals, two dispersal events were at higher level in the Digitipes phylogeny and were from the southern WG to the central and northern WG independently in the Early Paleocene, after the Cretaceous Volcanism. The remaining 11 dispersal events explained the species’ range expansions of which nine dispersals were from the southern WG to other biogeographic subdivisions in the Eocene-Miocene in the post-volcanic periods where species-level diversifications occurred. Taken together, these results suggest that southern WG might have served as a refuge for Digitipes species during Cretaceous volcanism.

Phylogenetics of scolopendromorph centipedes: can denser taxon sampling improve an artificial classification?

Previous phylogenetic analyses of the centipede order Scolopendromorpha indicated a fundamental division into blind and ocellate clades. These analyses corroborated the monophyly of most families and tribes but suggested that several species-rich, cosmopolitan genera in traditional and current classifications are polyphyletic. Denser taxon sampling is applied to a dataset of 122 morphological characters and sequences for four nuclear and mitochondrial loci. Phylogenetic analyses including 98 species and subspecies of Scolopendromorpha employ parsimony under dynamic and static homology schemes as well as maximum likelihood and Bayesian inference of multiple sequence alignments. The monotypic Australian genera Notiasemus and Kanparka nest within Cormocephalus and Scolopendra, respectively, and the New Caledonian Campylostigmus is likewise a clade within Cormocephalus. New World Scolopendra are more closely related to Hemiscolopendra and Arthrorhabdus than to Scolopendra s.s., which is instead closely allied to Asanada; the tribe Asanadini nests within Scolopendrini for molecular and combined datasets. The generic classification of Otostigmini has a poor fit to phylogenetic relationships, although nodal support within this tribe is weak. New synonymies are proposed for Ectonocryptopinae Shelley & Mercurio, 2005 (= Newportiinae Pocock, 1896), Asanadini Verhoeff, 1907 (= Scolopendrini Leach, 1814), and Kanparka Waldock & Edgecombe, 2012 (= Scolopendra Linnaeus, 1758). Scolopendrid systematics largely depicts incongruence between phylogeny and classification rather than between morphology and molecules.

Coalescent method in conjunction with niche modeling reveals cryptic diversity among centipedes in the Western Ghats of South India

BACKGROUND

There has been growing interest in integrative taxonomy that uses data from multiple disciplines for species delimitation. Typically, in such studies, monophyly is taken as a proxy for taxonomic distinctiveness and these units are treated as potential species. However, monophyly could arise due to stochastic processes. Thus here, we have employed a recently developed tool based on coalescent approach to ascertain the taxonomic distinctiveness of various monophyletic units. Subsequently, the species status of these taxonomic units was further tested using corroborative evidence from morphology and ecology. This inter-disciplinary approach was implemented on endemic centipedes of the genus Digitipes (Attems 1930) from the Western Ghats (WG) biodiversity hotspot of India. The species of the genus Digitipes are morphologically conserved, despite their ancient late Cretaceous origin.

PRINCIPAL FINDINGS

Our coalescent analysis based on mitochondrial dataset indicated the presence of nine putative species. The integrative approach, which includes nuclear, morphology, and climate datasets supported distinctiveness of eight putative species, of which three represent described species and five were new species. Among the five new species, three were morphologically cryptic species, emphasizing the effectiveness of this approach in discovering cryptic diversity in less explored areas of the tropics like the WG. In addition, species pairs showed variable divergence along the molecular, morphological and climate axes.

CONCLUSIONS

A multidisciplinary approach illustrated here is successful in discovering cryptic diversity with an indication that the current estimates of invertebrate species richness for the WG might have been underestimated. Additionally, the importance of measuring multiple secondary properties of species while defining species boundaries was highlighted given variable divergence of each species pair across the disciplines.