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Map of Vietnam and Cambodia where GTI joint expeditions between the teams from RBINS, the Institute of Ecology and Biological Resources (Vietnam), the VNMN, and the RUPP in Cambodia have conducted fieldwork between 2010 and 2019. All sampled locations are marked, with the green stars indicating locations where leaf insect specimens were located and the red circles denoting sampled sites where leaf insects were not encountered.
Source publication
While the leaf insects (Phylliidae) are a well-supported group within Phasmatodea, the genus Phyllium Illiger, 1798 has repeatedly been recovered as paraphyletic. Here, the Phyllium (Phyllium) celebicum species group is reviewed and its distinctiveness from the remaining Phylliini genera and subgenera in a phyloge- netic context based on morphologi...
Citations
... Some papers provided more than one genus-level key either because males and females were treated separately (n = 3 papers, Cumming et al. 2021;Cumming and Le Tirant 2022;Benda et al. 2022) or because the new taxa belonged to different intermediate taxonomic levels (n = 2 papers, Brunke 2021, Sharkey et al. 2021. Thus, the number of keys assessed was slightly larger than the number of papers that included keys. ...
Large numbers of new taxa are described annually and while there is a great need to make them identifiable, there seems little consistency in how this might be facilitated. 427 papers published in 2021 and 2022 were surveyed, which described 587 new insect genera. Only 136 of these papers included keys, and these allowed the identification of 233 of the new genera (31.9% of papers and 39.7% of the new genera). The proportion of papers that included a key varied significantly among insect orders but not among the handful of journals wherein the bulk of the new genera were described. Overall, for 17 key-related variables assessed in a binary fashion (optimal vs suboptimal), the average key had almost six criteria that were scored as being suboptimal. For example, less than one-fifth facilitated retracing and less than 12% had illustrated keys where the images were conveniently located close to the relevant key couplets. Progress towards confirming a putative identification was possible in all papers, through the inclusion of a diagnosis, habitus images, or both.
Based upon this analysis, and expanding on previous suggestions for key construction, 23 recommendations are made on how to make an identification key maximally useful for users and I indicate the relative ease with which each could be adhered to. Identification keys should accompany all new taxon descriptions, guidelines for effective key construction should be added to journals’ instructions to authors, editors and reviewers should check keys carefully, and publishers should be attentive to the needs of users through, for example, permitting duplication of images to make keys easier to use. Recommendations are likely relevant to all levels in the taxonomic hierarchy for all organisms, despite the data being derived from generic-level keys for insects.
... Several phylliid eggs possess similar pinnae like those of P. philippinicum. However, the eggs of different subgroups of Phylliidae show a broad range of other, distinctly different exochorionic surface structures and even egg shapes (Figs. 1, 2, for overview see [2,21,[27][28][29][30][31]). It is likely that differences in the morphology of the exochorionic appendages are due to adaptations to different substrates the eggs should more likely be attached to, such as differences in the roughness, hydrophobicity or hydrophilicity, or the presence of certain features (like trichomes) on the plant leaves they should adhere to. ...
... Features of the egg morphology of Phylliidae have been used frequently for taxonomic characterisation of certain subgroups as the eggs often possess prominent diagnostic traits distinguishing closely related and extremely similar taxa [e.g. 9,21,28,31,33]. However, phylogenetic studies of Phylliidae have shown that some taxa with similar egg features are not closely related, as for instance Pulchriphyllium giganteum (Hausleithner, 1984) and Walaphyllium spp. ...
... The phylogenetic analysis was based on the dataset published by Bank et al. [1] and augmented by three additional species that we investigated in the present study: Genetic data for Cryptophyllium khmer Cumming et al., 2021 and C. liyananae Cumming et al., 2021 were obtained from Cumming et al. [31], and for an additional specimen of Phyllium tobeloense, sequence data were generated as outlined elsewhere [1,40]. Please, refer to Additional file 3: Table S3 for details on the taxon and gene sampling including the GenBank accession numbers. ...
Phylliidae are herbivorous insects exhibiting impressive cryptic masquerade and are colloquially called “walking leaves”. They imitate angiosperm leaves and their eggs often resemble plant seeds structurally and in some cases functionally. Despite overall morphological similarity of adult Phylliidae, their eggs reveal a significant diversity in overall shape and exochorionic surface features. Previous studies have shown that the eggs of most Phylliidae possess a specialised attachment mechanism with hierarchical exochorionic fan-like structures (pinnae), which are mantled by a film of an adhesive secretion (glue). The folded pinnae and glue respond to water contact, with the fibrous pinnae expanding and the glue being capable of reversible liquefaction. In general, the eggs of phylliids appear to exhibit
varying structures that were suggested to represent specific adaptations to the different environments the eggs are deposited in. Here, we investigated the diversity of phylliid eggs and the functional morphology of their exochorionic
structure. Based on the examination of all phylliid taxa for which the eggs are known, we were able to characterise eleven different morphological types. We explored the adhesiveness of these different egg morphotypes and experimentally
compared the attachment performance on a broad range of substrates with different surface roughness, surface chemistry and tested whether the adhesion is replicable after detachment in multiple cycles. Furthermore, we used molecular phylogenetic methods to reconstruct the evolutionary history of different egg types and their adhesive systems within this lineage, based on 53 phylliid taxa. Our results suggest that the egg morphology is congruent with the phylogenetic relationships within Phylliidae. The morphological differences are likely caused by adaptations
to the specific environmental requirements for the particular clades, as the egg morphology has an influence on the performance regarding the surface roughness. Furthermore, we show that different pinnae and the adhesive glue evolved convergently in different species. While the evolution of the Phylliidae in general appears to be non-adaptive judging on the strong similarity of the adults and nymphs of most species, the eggs represent a stage with complex and rather diverse functional adaptations including mechanisms for both fixation and dispersal of the eggs.
... Molecular species delimitation has been successfully used in phasmids in several instances (Glaw et al., 2019;Bank et al., 2021;Cumming et al., 2021). Velonà et al. (2015) first applied DNA barcoding on 16 Australian stick insect taxa, and retrieved a high differentiation among three putative morphospecies of the genus Candovia Stål, 1875: Candovia spp. ...
The Phasmida genus Candovia comprises nine traditionally recognized species, all endemic to Australia. In this study, Candovia diversity is explored through molecular species-delimitation analyses using the COIFol gene fragment and phylogenetic inferences leveraging seven additional mitochondrial and nuclear loci. Molecular results were integrated with morphological observations, leading us to confirm the already described species and to the delineation of several new taxa and of the new genus Paracandovia. New Candovia species from various parts of Queensland and New South Wales are described and illustrated (C. alata sp. nov., C. byfieldensis sp. nov., C. dalgleishae sp. nov., C. eungellensis sp. nov., C. karasi sp. nov., C. koensi sp. nov. andC. wollumbinensis sp. nov.). New combinations are proposed and species removed from synonymy with the erection of the new genus Paracandovia (P. cercata stat. rev., comb. nov., P. longipes stat. rev., comb. nov., P. pallida comb. nov., P. peridromes comb. nov., P. tenera stat. rev., comb. nov.). Phylogenetic analyses suggest that the egg capitulum may have independently evolved multiple times throughout the evolutionary history of these insects. Furthermore, two newly described species represent the first taxa with fully developed wings in this previously considered apterous clade.
... The characters of the male vomer are frequently used when describing or differentiating stick insect taxa (Bradler 2009, Bresseel and Constant 2018a, Cumming et al. 2021. The nomenclature proposed here for the dissected vomer can be used in nearly all species, and the structure of the vomer provides useful differential characters when studied from different angles. ...
... The apical portion of the body of the vomer is often upcurved and armed with one to multiple spines. In many species the vomer ends in a single apical spine (Fig. 4, as), referred to as hook(s) or prong(s) by several authors (Bradler 1999, Bradler et al. 2014, Cumming et al. 2021. The apex can sometimes be more complex, bearing two (Neooxyartes Ho, 2018, Cryptophyllium) or more (Spinohirasea Zompro, 2002, Paramenexenus Redtenbacher, 1908 sometimes blunt, spines (Hennemann 2007, Bresseel and Constant 2018a, Bradler et al. 2014, Cumming et al. 2021. ...
... In many species the vomer ends in a single apical spine (Fig. 4, as), referred to as hook(s) or prong(s) by several authors (Bradler 1999, Bradler et al. 2014, Cumming et al. 2021. The apex can sometimes be more complex, bearing two (Neooxyartes Ho, 2018, Cryptophyllium) or more (Spinohirasea Zompro, 2002, Paramenexenus Redtenbacher, 1908 sometimes blunt, spines (Hennemann 2007, Bresseel and Constant 2018a, Bradler et al. 2014, Cumming et al. 2021. The body of the vomer can be symmetrical (Neooxyartes) to asymmetrical (Cryptophyllium) depending on the size and direction of the spine(s) Constant 2018a, Cumming et al. 2021). ...
A new species of Presbistus Kirby, 1896, Presbistus vitivorus sp. nov., is described from Cambodia based on both sexes, nymphs, and eggs. Male genitalia and vomer are described and figured. Illustrations of adults, nymphs, specimens in situ, host plants, a distribution map and records on biology and breeding in captivity are provided. The host plants of the species belong to the family Vitaceae. The genus Presbistus and the family Aschiphasmatidae are recorded from Cambodia for the first time. The species diversity and the distribution of the genus are discussed, and it is shown that the genus is restricted to Sundaland. A nomenclature for the morphology of the dissected vomer is proposed and tries to homologize the previously used terms.
... For the outgroup, we further included two species of Embioptera, which were repeatedly recovered as the sister group of Phasmatodea [4,30,56,121]. Our gene sampling comprised three nuclear (18S, 28S, H3) and four mitochondrial loci (12S, 16S, COI, COII) of which data for numerous specimens were already available on GenBank [30,54,55,71,80,89,90,101,[122][123][124][125][126][127][128][129][130][131]. Additionally, we generated new data for 194 specimens following the protocol given by Bank et al. [80] with primers adopted from Buckley et al. [124] and Robertson et al. [55] (see Bank et al. [80]), and deposited the sequences in GenBank under accession numbers OK314533-OK314857, OK324156-OK324324, OK333379-OK334012 (Additional file 3: Table S7). ...
Background
The re-evolution of complex characters is generally considered impossible, yet, studies of recent years have provided several examples of phenotypic reversals shown to violate Dollo’s law. Along these lines, the regain of wings in stick and leaf insects (Phasmatodea) was hypothesised to have occurred several times independently after an ancestral loss, a scenario controversially discussed among evolutionary biologists due to overestimation of the potential for trait reacquisition as well as to the lack of taxonomic data.
Results
We revisited the recovery of wings by reconstructing a phylogeny based on a comprehensive taxon sample of over 500 representative phasmatodean species to infer the evolutionary history of wings. We additionally explored the presence of ocelli, the photoreceptive organs used for flight stabilisation in winged insects, which might provide further information for interpreting flight evolution. Our findings support an ancestral loss of wings and that the ancestors of most major lineages were wingless. While the evolution of ocelli was estimated to be dependent on the presence of (fully-developed) wings, ocelli are nevertheless absent in the majority of all examined winged species and only appear in the members of few subordinate clades, albeit winged and volant taxa are found in every euphasmatodean lineage.
Conclusion
In this study, we explored the evolutionary history of wings in Phasmatodea and demonstrate that the disjunct distribution of ocelli substantiates the hypothesis on their regain and thus on trait reacquisition in general. Evidence from the fossil record as well as future studies focussing on the underlying genetic mechanisms are needed to validate our findings and to further assess the evolutionary process of phenotypic reversals.
... Colors correspond to different body sizes relative to the original model Table 4 The effects of body size and shape on various aerodynamic variables, as predicted by the CFD models Results of type I ANOVA from linear models contrasting the effects of body length and body aspect ratio on various aerodynamic variables (Fig. 6) their static safety factors for both adhesion and friction forces were still relatively lower than those of males. Male and female leaf insects also exhibit a spectacular interspecific variation in body shape related to leaf mimicry [24,26,61]. This variation is likely driven by masquerade and the advergence of the insect appearance to resemble the size and shape of its host plants' leaves. ...
Background
In most arthropods, adult females are larger than males, and male competition is a race to quickly locate and mate with scattered females (scramble competition polygyny). Variation in body size among males may confer advantages that depend on context. Smaller males may be favored due to more efficient locomotion leading to higher mobility during mate searching. Alternatively, larger males may benefit from increased speed and higher survivorship. While the relationship between male body size and mobility has been investigated in several systems, how different aspects of male body morphology specifically affect their locomotor performance in different contexts is often unclear.
Results
Using a combination of empirical measures of flight performance and modelling of body aerodynamics, we show that large body size impairs flight performance in male leaf insects ( Phyllium philippinicum ), a species where relatively small and skinny males fly through the canopy in search of large sedentary females. Smaller males were more agile in the air and ascended more rapidly during flight. Our models further predicted that variation in body shape would affect body lift and drag but suggested that flight costs may not explain the evolution of strong sexual dimorphism in body shape in this species. Finally, empirical measurements of substrate adhesion and subsequent modelling of landing impact forces suggested that smaller males had a lower risk of detaching from the substrates on which they walk and land.
Conclusions
By showing that male body size impairs their flight and substrate adhesion performance, we provide support to the hypothesis that smaller scrambling males benefit from an increased locomotor performance and shed light on the evolution of sexual dimorphism in scramble competition mating systems.
... Misidentification, overestimation of species' distributions and the unreliability of the highly variable morphological traits 35 had resulted in a chaotic taxonomy that only recently started to be overcome by extensive morphological examinations (e.g., Cumming et al. 36,37 ). Captive breeding and molecular analysis have further helped to shed light on the phylogenetic relationships and to match up males and females of leaf insects [38][39][40] . According to the most recent studies, Phylliidae currently includes six genera (Chitoniscus, Cryptophyllium, Microphyllium, Nanophyllium, Phyllium and Pseudomicrophyllium) with most species pertaining to Phyllium, which is further divided into four subgenera (Comptaphyllium, Phyllium, Pulchriphyllium and Walaphyllium). ...
... One of these species groups was recently revealed to be distinct to the remaining phylliids and was therefore transferred to the newly erected genus Cryptophyllium 40 . Molecular analyses preceding this study had already repeatedly demonstrated that Phyllium (and Chitoniscus) are paraphyletic and that the Phylliidae are in need of revision 24,25,29,40 . ...
... [2][3][4][5]. However, Chitoniscus and Phyllium are recovered as paraphyletic, which was already shown in previous studies based on molecular data 24,25,29,40,41 . The Chitoniscus spp. ...
The insect order Phasmatodea is known for large slender insects masquerading as twigs or bark. In contrast to these so-called stick insects, the subordinated clade of leaf insects (Phylliidae) are dorso-ventrally flattened and therefore resemble leaves in a unique way. Here we show that the origin of extant leaf insects lies in the Australasian/Pacific region with subsequent dispersal westwards to mainland Asia and colonisation of most Southeast Asian landmasses. We further hypothesise that the clade originated in the Early Eocene after the emergence of angiosperm-dominated rainforests. The genus Phyllium to which most of thẽ 100 described species pertain is recovered as paraphyletic and its three non-nominate subgenera are recovered as distinct, monophyletic groups and are consequently elevated to genus rank. This first phylogeny covering all major phylliid groups provides the basis for future studies on their taxonomy and a framework to unveil more of their cryptic and underestimated diversity.
Several stick insects occurring in Brazil belong to the Diapheromerinae. Before this work, the Brazilian genus Exocnophila contained three species known only from females, Exocnophila exintegra Zompro, 2001, Exocnophila tuberculata (Brunner von Wattenwyl, 1907) and Exocnophila cornuta (Brunner von Wattenwyl, 1907). Based on recently collected material, we found that the males of Exocnophila are assigned to another genus in the Diapheromerinae, the heterogeneous Bacteria. Here we show that the type species Exocnophila exintegra Zompro, 2001 syn. nov. is a junior synonym of Bacteria brevitarsata Brunner von Wattenwyl, 1907, which is transferred and redescribed as Exocnophila brevitarsata comb. nov.. We also transfer and redescribe Bacteria hastata as Exocnophila hastata comb. nov. and propose a new species, Exocnophila ovifuscum sp. nov., from Rio de Janeiro state, Brazil, with descriptions of females, males and eggs. We provide the first biological observations for the genus and a short discussion about its relationships.
https://www.schweizerbart.de/publications/detail/isbn/9783510550531/Zoologica_Vol_166
Calvisia is a colorful winged stick insect genus consisting of 6 subgenera and 44 species widely distributed in temperate and tropical Asia. C. medogensis syn. nov. was discovered in Mêdog, Xizang (Tibet), China and is so far the only species recorded from China. We here propose that C. medogensis syn. nov. is a synonym of C. fuscoalata after checking type specimens of both species. New materials studied are deposited in Yunnan Agricultural University, China (YNAU).
