Complete mitochondrial genome of the deep-water epibiotic stalked barnacle, Glyptelasma annandalei (Cirripedia, Lepadiformes, Poecilasmatidae)

The Mitochondrial Genome of the Globally Invasive Barnacle Megabalanus coccopoma Darwin 1854 (Crustacea: Balanomorpha): Rearrangement and Phylogenetic Consideration within Balanomorpha

Megabalanus coccopoma (Darwin, 1854) is a globally invasive species in Balanomorpha (Crustacea). This species is a model organism for studying marine pollution and ecology. However, its mitogenome remains unknown. The mitogenome sequencing of M. coccopoma is completed in the present study. It has a 15,098 bp in length, including 13 protein-coding genes (PCGs), 2 ribosomal RNAs (rRNAs), 22 transfer RNAs (tRNAs), along with a putative regulatory area. A substantial A+T bias was observed in the genome composition (68.2%), along with a negative AT (0.82) and GC (−0.136) skew. Compared to the gene sequence of the ground model of pan-crustacea, 13 gene clusters (or genes), such as 10 tRNAs and 3 PCGs, were observed in a different order. This was in line with the previously observed large-scale gene rearrangements of Balanomorpha. Among the 37 genes, the gene cluster (M-nad2-W-cox1-L2-cox2-D-atp8-atp6-cox3-G- nad3-R-N-A-E-S1) Balanomorpha was conserved. Furthermore, phylogeny analysis indicated that the existing Balanomorpha species family was divided into nine rearrangement patterns, supporting the polyphyly of Balanoidea.

The evolutionary diversity of barnacles, with an updated classification of fossil and living forms

We present a comprehensive revision and synthesis of the higher-level classification of the barnacles (Crustacea: Thecostraca) to the genus level and including both extant and fossils forms. We provide estimates of the number of species in each group. Our classification scheme has been updated based on insights from recent phylogenetic studies and attempts to adjust the higher-level classifications to represent evolutionary lineages better, while documenting the evolutionary diversity of the barnacles. Except where specifically noted, recognized taxa down to family are argued to be monophyletic from molecular analysis and/or morphological data. Our resulting classification divides the Thecostraca into the subclasses Facetotecta, Ascothoracida and Cirripedia. The whole class now contains 14 orders, 65 families and 367 genera. We estimate that barnacles consist of 2116 species. The taxonomy is accompanied by a discussion of major morphological events in barnacle evolution and justifications for the various rearrangements we propose.

Complete mitochondrial genome of Tetraclita squamosa squamosa (Sessilia: Tetraclitidae) from China and phylogeny within Cirripedia

Here we present the complete mitochondrial genome of Tetraclita squamosasquamosa, which is 15,191 bp in length with 67.20% AT content. It contains 13 protein-coding genes, 2 ribosomal-RNA genes and 22 transfer-RNA genes. All PCGs except nad4l in T. squamosasquamosa start with ATN, and terminated with a complete stop codon, except nad3. Phylogenetic analysis based on mitochondrial PCGs shows that T. squamosasquamosa is clustered with T. serrata into a branch (BP = 100). Our result is consistent with previous reports that genus Tetraclita and family Tetraclitidae are not monophyletic. This study contributes to further phylogenetic analysis within Cirripedia. 

The first mitochondrial genome of Megabalanus tintinnabulum (Sessilia: Balanidae) from China: phylogeny within Cirripedia based on mitochondrial genes

Here we present the complete mitochondrial genome of Megabalanus tintinnabulum. The genome is 15,107 bp in length with a 67.35% AT content. It contains 13 protein-coding genes (PCGs), 2 rRNAs genes, and 22 tRNAs. Both rRNAs are encoded on the light strand, as in the other crustacean and barnacle mitochondrial genomes. Besides five tRNAs are encoded on the light strand (nad1, trnV, trnL1, trnC, trnQ, and trnK). Only one PCG is encoded on the light strand (nad1), whereas the other 12 PCGs are located on the heavy strand, which is consistent with M. ajax. Phylogenetic analysis based on mitochondrial PCGs shows that M. tintinnabulum is clustered with M. ajax into a branch (BP = 100), and the group with M. volcano with high support. This study contributes to further phylogenetic analysis within Cirripedia.