A Mysterious Asian Firefly Genus, Oculogryphus Jeng, Engel & Yang (Coleoptera, Lampyridae): The First Complete Mitochondrial Genome and Its Phylogenetic Implications.

The firefly genus Oculogryphus Jeng, Engel & Yang, 2007 is a rare-species group endemic to Asia. Since its establishment, its position has been controversial but never rigorously tested. To address this perplexing issue, we are the first to present the complete mitochondrial sequence of Oculogryphus, using the material of O. chenghoiyanae Yiu & Jeng, 2018 determined through a comprehensive morphological identification. Our analyses demonstrate that its mitogenome exhibits similar characteristics to that of Stenocladius, including a rearranged gene order between trnC and trnW, and a long intergenic spacer (702 bp) between the two rearranged genes, within which six remnants (29 bp) of trnW were identified. Further, we incorporated this sequence into phylogenetic analyses of Lampyridae based on different molecular markers and datasets using ML and BI analyses. The results consistently place Oculogryphus within the same clade as Stenocladius in all topologies, and the gene rearrangement is a synapomorphy for this clade. It suggests that Oculogryphus should be classified together with Stenocladius in the subfamily Ototretinae at the moment. This study provides molecular evidence confirming the close relationship between Oculogryphus and Stenocladius and discovers a new phylogenetic marker helpful in clarifying the monophyly of Ototretinae, which also sheds a new light on firefly evolution.

Mitochondrial genomes of Sternochetus species (Coleoptera: Curculionidae) and the phylogenetic implications.

The three weevil species, Sternochetus gravis, S. mangiferae, and S. olivieri, have all been reported to be serious pests of mango fruits. Morphology, biology, and various management approaches of these economically important weevils have been well studied. However, no mitochondrial genomes have been reported from the genus Sternochetus. Herein, we assembled mitogenomes of all the three Sternochetus species to reveal their mitogenomic characteristics. A DNA library of 350 bp insert size was constructed and sequenced in Illumina's HiSeq 6000 platform with a pair-end 150 bp sequencing strategy by Novogene. The sequence reads were assembled using GetOrganelle v1.7.1 and the genes were annotated by Geneious Prime 2021.0.3 and MITOS Web Server. Coupled with 61 published mitogenomes from 13 subfamilies of Curculionidae, we reconstructed phylogenetic trees to resolve evolutionary relationships of these closely related species and also examined subfamily-level classification among Curculionidae. All three mitogenomes are double-stranded circular molecules with 22 transfer RNA genes, 13 protein-coding genes (PCGs), 2 ribosomal RNA genes, and 1 noncoding control region as in other insects. Higher interspecific nucleotide divergence (about 10%) of 13 PCGs indicated these three Sternochetus species diverged a long time ago. Phylogenetic analyses using both maximum likelihood and Bayesian inference methods showed that Sternochetus falls into the basal clade of Cryptorhynchini, a tribe in the subfamily Molytinae. The relationship of S. olivieri as a sister species to S. gravis + S. mangiferae was strongly supported. The monophyly of Cryptorhynchini was also well supported whereas Molytinae was suggested to be a polyphyletic group.

First complete mitochondrial genomes of Ototretinae (Coleoptera, Lampyridae) with evolutionary insights into the gene rearrangement.

The subfamily Ototretinae represents an important and unusual lineage of fireflies. Here, we sequenced and annotated three mitogenomes for this subfamily, with two Stenocladius species and one Drilaster species as representatives. The mitogenome of Stenocladius exhibits a rearranged gene order between trnC and trnW caused by transposition, which is a novel finding in Lampyridae. Meanwhile, a long intergenic space (241 to 376 bp) exists between the two rearranged genes, and some remnants (23 bp) of trnW are present within this non-coding region. Moreover, phylogenetic analyses did not recover the monophyly of Ototretinae, in which Drilaster is shown at a basal lineage in Lampyridae, but Stenocladius seems more related to Luciolinae. Therefore, the gene rearrangement in Stenocladius is presumed to result from independent evolutionary events, suggesting that this genus should be placed in a separate lineage. Nevertheless, more representative mitogenomes from different groups are required to verify the present results.

The complete mitochondrial genome sequence and phylogenetic analysis of Lycocerus asperipennis (Coleoptera, Cantharidae).

The complete mitochondrial genome of a common Chinese soldier beetle was sequenced, Lycocerus asperipennis (Coleoptera, Cantharidae, Cantharinae). The mitogenome is a double-stranded circular molecule, and the obtained sequence with 13 protein-coding genes (PCGs), 22 tRNA genes, 2 rRNA subunits, and an AT-rich region, as in other insects. Total length of this mitogenome is 16162 bp and the composition of each base is A (41.5%), T (37.7%), C (12.4%), G (8.4%), respectively. The phylogenetic tree analysis using 16 species of Elateriformia shows that L. asperipennis is closest to Chauliognathus opacus, which belongs to the subfamily Chauliognathinae of Cantharidae.

The complete mitogenome of Lycostomus sp. (Elateroidea: Lycidae).

The complete mitochondrial genome of a net-winged beetle was sequenced, Lycostomus sp. (Coleoptera: Lycidae). The total length of this mitogenome is 16096 bp and the composition of each base is A (41.1%), T (31.9%), C (17.1%), G (9.9%), respectively. The gene arrangement of this beetle mt genome is the same as other insects. The phylogenetic tree shows that Lycostomus sp. is closest to Platerodrilus sp. with robust statistical support, which confirms the monophyly of Lycidae.