Topological support and data quality can only be assessed through multiple tests in reviewing Blattodea phylogeny

Two new genera (Vittiblatta gen. nov. and Planiblatta gen. nov.) of Blattinae (Blattodea, Blattidae) from Southwest China and the discovery of chirally dimorphic male genitalia in Vittiblattapunctata sp. nov

This study examines Blattinae samples from Southwest China collected in recent years. Based on morphological characters, we establish two genera, Vittiblattagen. nov. and Planiblattagen. nov., and describe four new species, Vittiblattapunctata Luo & Wang, sp. nov., Vittiblattaferruginea Luo & Wang, sp. nov., Vittiblattaundulata Luo & Wang, sp. nov., and Planiblattacrassispina Luo & Wang, sp. nov. These two new genera resemble Periplaneta s.s., but are easily distinguished from it and other genera of Blattinae by morphological characters (genital sclerite L4C). Our results indicate that sclerites L4C and R1G of male genitalia might be important in species delimitation of Blattinae. In addition, chiral dimorphism is found in male genitalia of Vittiblattapunctata sp. nov.

Advances in the understanding of Blattodea evolution: Insights from phylotranscriptomics and spermathecae

Cockroaches, an ancient and diverse group of insects on earth that originated in the Carboniferous, displays a wide array of morphology or biology diversity. The spermatheca is an organ of the insect reproductive system; the diversity of spermathecae might be the adaption to different mating and sperm storage strategies. Yet a consensus about the phylogenetic relationships among the main lineages of Blattodea and the evolution of spermatheca has not been reached until now. Here we added the transcriptome data of Anaplectidae for the first time and supplemented other family level groups (such as Blaberidae, Corydiidae) to address the pending issues. Our results showed that Blattoidea was recovered as sister to Corydioidea, which was strongly supported by molecular evidence. In Blattoidea, (Lamproblattidae + Anaplectidae) + (Cryptocercidae + Termitoidae) was strongly supported by our molecular data. In Blaberoidea, Pseudophyllodromiidae and Blaberidae were recovered to be monophyletic, while Blattellidae was found to be paraphyletic with respect to Malaccina. Ectobius sylvestris + Malaccina discoidalis formed the sister group to other Blaberoidea; Blattellidae (except Malaccina discoidalis) + Nyctiboridae was found as the sister of Blaberidae. Corydiidae was recovered to be non-monophyletic due to the embedding of Nocticola sp. Our ASR analysis of spermatheca suggested that primary spermathecae were present in the common ancestor, and it transformed at least six times during the evolutionary history of Blattodea. The evolution of spermatheca could be described as a unidirectional trend: the increased size to accommodate more sperm. Furthermore, major splits within the existing genera of cockroaches occurred in the Upper Paleogene to Neogene. Our study provides strong support for the relationship among three superfamilies and offers some new insights into the phylogeny of cockroaches. Meanwhile, this study also provides basic knowledge on the evolution of spermathecae and reproductive patterns.

Morphological, functional, and phylogenetic aspects of the head capsule of the cockroach Ergaula capucina (Insecta/Blattodea)

Background

Cockroaches are usually typical omnivorous detritivores and their cephalic morphology is considered to be ancestral in various aspects. Thus, several studies addressed the morphology and function of the blattodean head, and the cockroach usually serves as a model for standard mouthparts in text books. However, so far only two of the three major lineages of Blattodea have been studied and no detailed information for the head of any Corydioidea was available. The present study closes this gap by providing a detailed morphological description of the head of Ergaula capucina, studying some important functional parameters of the mandible and discussing it in a phylogenetic framework.

Methods

The cephalic morphology of Ergaula studied in detail using a broad set of different techniques including digital microscopy, µ-computed tomography, and 3-dimensional reconstructions. Concerning the functional morphology of the mandible, we compared the volume and effective cross sections of the eight compartments of the primary mandibular adductor muscle for Ergaula, Blattella germanica, and Salganea rossi and measured the mechanical advantage, i.e., the force transmission ratio for all teeth of the mandible of Ergaula.

Results

The head capsule of Ergaula is characterized by a strong sexual dimorphism and typical orthopteran mouthparts. It resembles the head capsule of other roaches in several respects and confirms oesotendons, the reduction of the mesal occelus, and bipartite M. verticopharyngealis and M. hypopharyngosalivaris as blattodean apomorphies. But it also shows some unique adaptations. It is the first described cockroach that lacks the dorsal tentorial arms which has various consequences for the cephalic musculature. On the maxillary lacinia, Ergaula is the first described blattodean to show strong and blunt setae instead of a lacinula, which might be homologues to the dentisetae of dragonflies and mayflies. Like other corydiid roaches that inhabit xeric areas, Ergaula has an atmospheric water-vapor absorption mechanism that includes a gland and a ductus on the epipharnyx and bladders on the hypopharynx. The mandibular adductor is in cockroaches asymmetric, a pattern not found in termites, mantids, or other closely related insects.

An empirical test of the relationship between the bootstrap and likelihood ratio support in maximum likelihood phylogenetic analysis

In maximum likelihood (ML), the support for a clade can be calculated directly as the likelihood ratio (LR) or log-likelihood difference (S, LLD) of the best trees with and without the clade of interest. However, bootstrap (BS) clade frequencies are more pervasive in ML phylogenetics and are almost universally interpreted as measuring support. In addition to theoretical arguments against that interpretation, BS has several undesirable attributes for a support measure. For example, it does not vary in proportion to optimality or identify clades that are rejected by the evidence and can be overestimated due to missing data. Nevertheless, if BS is a reliable predictor of S, then it might be an efficient indirect method of measuring support-an attractive possibility, given the speed of many BS implementations. To assess the relationship between S and BS, we analyzed 106 empirical datasets retrieved from TreeBASE. Also, to evaluate the degree to which S and BS are affected by the number of replicates during suboptimal tree searches for S and pseudoreplicates during BS estimation, we randomly selected 5 of the 106 datasets and analyzed them using variable numbers of replicates and pseudoreplicates, respectively. The correlation between S and BS was extremely weak in the datasets we analyzed. Increasing the number of replicates during tree search decreased the estimated values of S for most clades, but the magnitude of change was small. In contrast, although increasing pseudoreplicates affected BS values for only approximately 40% of clades, values both increased and decreased, and they did so at much greater magnitudes. Increasing replicates/pseudoreplicates affected the rank order of clades in each tree for both S and BS. Our findings show decisively that BS is not an efficient indirect method of measuring support and suggest that even quite superficial searches to calculate S provide better estimates of support.

An integrative phylogenomic approach to elucidate the evolutionary history and divergence times of Neuropterida (Insecta: Holometabola)

BACKGROUND

The latest advancements in DNA sequencing technologies have facilitated the resolution of the phylogeny of insects, yet parts of the tree of Holometabola remain unresolved. The phylogeny of Neuropterida has been extensively studied, but no strong consensus exists concerning the phylogenetic relationships within the order Neuroptera. Here, we assembled a novel transcriptomic dataset to address previously unresolved issues in the phylogeny of Neuropterida and to infer divergence times within the group. We tested the robustness of our phylogenetic estimates by comparing summary coalescent and concatenation-based phylogenetic approaches and by employing different quartet-based measures of phylogenomic incongruence, combined with data permutations.

RESULTS

Our results suggest that the order Raphidioptera is sister to Neuroptera + Megaloptera. Coniopterygidae is inferred as sister to all remaining neuropteran families suggesting that larval cryptonephry could be a ground plan feature of Neuroptera. A clade that includes Nevrorthidae, Osmylidae, and Sisyridae (i.e. Osmyloidea) is inferred as sister to all other Neuroptera except Coniopterygidae, and Dilaridae is placed as sister to all remaining neuropteran families. Ithonidae is inferred as the sister group of monophyletic Myrmeleontiformia. The phylogenetic affinities of Chrysopidae and Hemerobiidae were dependent on the data type analyzed, and quartet-based analyses showed only weak support for the placement of Hemerobiidae as sister to Ithonidae + Myrmeleontiformia. Our molecular dating analyses suggest that most families of Neuropterida started to diversify in the Jurassic and our ancestral character state reconstructions suggest a primarily terrestrial environment of the larvae of Neuropterida and Neuroptera.

CONCLUSION

Our extensive phylogenomic analyses consolidate several key aspects in the backbone phylogeny of Neuropterida, such as the basal placement of Coniopterygidae within Neuroptera and the monophyly of Osmyloidea. Furthermore, they provide new insights into the timing of diversification of Neuropterida. Despite the vast amount of analyzed molecular data, we found that certain nodes in the tree of Neuroptera are not robustly resolved. Therefore, we emphasize the importance of integrating the results of morphological analyses with those of sequence-based phylogenomics. We also suggest that comparative analyses of genomic meta-characters should be incorporated into future phylogenomic studies of Neuropterida.

Phylogenetic analysis provides insights into the evolution of Asian fireflies and adult bioluminescence

Fireflies are one of the best-known examples of luminescent organisms. The limited geographic distribution and rarity of some firefly genera have hindered molecular phylogenetic analysis, resulting in uncertainty in regard to firefly phylogeny. Here, using genome skimming next-generation sequencing, we sequenced 23 Asian firefly species from 15 genera (Lampyridae: 14; Rhagophthalmidae: one) and assembled their mitochondrial genomes (mitogenomes) and nuclear ribosomal DNA (rDNA) repeat unit. The mitogenomes (including 15 mitochondrial genes: COX1-3, ATP6&8, ND1-6&4L, CYTB, 12S, and 16S) were recovered for almost all 23 species; furthermore, three regions of the nuclear rDNA repeat unit (18S, 28S, and 5.8S) were recovered for 22 out of the 23 species. The mitogenomes of 11 genera and 22 species as well as the complete rDNA from 22 species are reported here for the first time. Combined with previously published sequences of mitochondrial and rDNA coding regions, 166 species (170 populations with four overlapping in Lampyridae) were included in the current analyses. We selected different species groups and coding regions to infer phylogenies, and then employed tree certainty (TC) and internode certainty (IC) to quantify any phylogenetic incongruence. Phylogenetic analysis of 18 coding regions (15 mitochondrial genes and three regions of the nuclear rDNA repeat unit) from different species groups showed that the 144-species selection group (excluding 22 species outside Lampyridae) had relatively high TC (101.39). Further phylogenetic analysis of the 144 species using different coding regions indicated that the phylogeny of the 13 coding regions (10 mitochondrial genes: COX1-2, ATP6&8, ND1, ND4-5, CYTB, 12S and 16S; three rDNA regions: 18S, 5.8S, and 28S) demonstrated higher TC (103.02) than the phylogenies based on the 18 coding regions (TC = 101.39), conserved-regions (c-regions, i.e., 12S, 16S, COX1, 18S, and 28S) (TC = 95.11), or conserved-sites (c-sites, TC = 92.31) for the mitochondrial genes. In contrast, the c-sites strengthened the deeper nodes of the 144-species phylogeny compared to the c-regions. All of the 144-species phylogenies using different coding regions (except the c-regions) consistently recovered the monophyly of each of the three luminous families and their combination (Lampyridae, Rhagophthalmidae, and Phengodidae) with high IC support. Our phylogenetic analyses clarified the position of firefly genera Lamprigera, Vesta, Stenocladius, Pyrocoelia, Diaphanes, Abscondita, Pygoluciola, Emeia, Pristolycus, and Menghuoius. We also inferred the evolutionary pattern of adult bioluminescence in Lampyridae based on the phylogenies of 166 and 144 species. Our data suggest that the common ancestor of Lampyridae possessed adult bioluminescence, with a higher loss rate than gain rate of bioluminescence during its lineage evolution. Our results provide insight into Asian firefly phylogeny, and also enrich mitogenome and rDNA data resources for further study.

An integrative phylogenomic approach illuminates the evolutionary history of cockroaches and termites (Blattodea)

Phylogenetic relationships among subgroups of cockroaches and termites are still matters of debate. Their divergence times and major phenotypic transitions during evolution are also not yet settled. We addressed these points by combining the first nuclear phylogenomic study of termites and cockroaches with a thorough approach to divergence time analysis, identification of endosymbionts, and reconstruction of ancestral morphological traits and behaviour. Analyses of the phylogenetic relationships within Blattodea robustly confirm previously uncertain hypotheses such as the sister-group relationship between Blaberoidea and remaining Blattodea, and Lamproblatta being the closest relative to the social and wood-feeding Cryptocercus and termites. Consequently, we propose new names for various clades in Blattodea: Cryptocercus + termites = Tutricablattae; Lamproblattidae + Tutricablattae = Kittrickea; and Blattoidea + Corydioidea = Solumblattodea. Our inferred divergence times contradict previous studies by showing that most subgroups of Blattodea evolved in the Cretaceous, reducing the gap between molecular estimates of divergence times and the fossil record. On a phenotypic level, the blattodean ground-plan is for egg packages to be laid directly in a hole while other forms of oviposition, including ovovivipary and vivipary, arose later. Finally, other changes in egg care strategy may have allowed for the adaptation of nest building and other novelties.