Abstract
The mitochondrial genome of Ircinia sp. (Dictyoceratida: Irciniidae) is a circular molecule of 16,037 bp in length, containing 14 protein-coding genes, 2 ribosomal RNA genes, 2 transfer RNA genes (trnW and trnM) and 13 non-coding segments. All genes are distributed in the same strand (H-strand). The overall base composition of the H-strand is as follows: T (37.84%), C (11.22%), A (24.81%), G (26.13%), with GC- and AT-skew of 0.399 and −0.208, respectively, reflecting unbalanced base composition between the two strands. The non-coding regions are 1190 bp in total length, with high AT content (76.31%). The current mitochondrial genome is identical to that of sibling species I. strobilina in gene order and contents, but differs from the latter in the presence of two kinds of repetitive sequences in the non-coding regions, of which one could form repetitive hairpin-forming elements.
Declaration of interest
This work was supported by the National Natural Science Foundation of China (40806055, 40572070 and 4072001), the Knowledge Innovation Project of the Chinese Academy of Science (KZCX2-YW-JC104), State Key Laboratory of Palaeobiology and Stratigraphy at Nanjing Institute of Geology and Palaeontology, CAS. The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this report.