Cretaceous crown male ant reveals the rise of modern lineages

Zool Res. 2024 Sep 18;45(5):983-989. doi: 10.24272/j.issn.2095-8137.2023.390.

Abstract

Most described Mesozoic ants belong to stem groups that existed only during the Cretaceous period. Previously, the earliest known crown ants were dated to the Turonian (Late Cretaceous, ca. 94-90 million years ago (Ma)) deposits found in the USA, Kazakhstan, and Botswana. However, the recent discovery of an alate male ant in Kachin amber from the earliest Cenomanian (ca. 99 Ma), representing a new genus and species, Antiquiformica alata, revises the narrative on ant diversification. Antiquiformica can be distinctly differentiated from all known male stem ants by its geniculate antennae with elongated scape, extending far beyond the occipital margin of the head and half the length of the funiculus, as well as its partly reduced forewing venation. Furthermore, the combination of a one-segmented waist with a well-developed node, elongated scape extending beyond the occipital margin, and reduced forewing venation, particularly the completely reduced m-cu and rs-m crossveins and absence of rm and mcu closed cells, firmly places the fossil within the extant subfamily Formicinae. Fourier transform infrared spectroscopy (FTIR) confirmed that the amber containing Antiquiformica alata originated from the Kachin mines in Myanmar. This discovery significantly revises our understanding of the early evolution of Formicinae. The presence of Antiquiformica in Cenomanian amber indicates that the subfamily Formicinae emerged at least by the start of the Late Cretaceous, with crown ants likely originating earlier during the earliest Cretaceous or possibly the Late Jurassic, although paleontological evidence is lacking to support the latter hypothesis.

大多数被描述的中生代蚂蚁属于仅生存在白垩纪的基干类群。目前已知最古老的冠群蚂蚁发现于美国、哈萨克斯坦和博茨瓦纳的土仑阶沉积中(晚白垩纪,约94–90 Ma)。然而,在克钦琥珀中发现的一个森诺曼阶早期的有翅雄蚁新种(约99 Ma)——翼古老蚁( Antiquiformica alata)改变了对蚂蚁类群分化的认识。古老蚁属( Antiquiformica)与所有已知的雄性蚂蚁明显不同:触角呈膝状;柄节较长,延伸远超过后头边缘,长度约为鞭小节的一半;前翅翅脉部分减少。此外,古老蚁属( Antiquiformica)具有一个发育良好的腹结节、延伸超过后头边缘的细长柄节、简化的前翅翅脉,尤其是前翅横脉m-cu和rs-m完全消失、翅室rm和mcu不闭合,这些特征都表明翼古老蚁属于现存的蚁亚科。傅里叶红外光谱(FTIR)结果表明这件琥珀来自缅甸克钦矿区。新化石的发现极大地改变了我们对蚁亚科早期演化的认识。在克钦琥珀(森诺曼阶)中发现的古老蚁属( Antiquiformica)证实蚁亚科至少在晚白垩的早期就已经出现,而冠群蚂蚁出现时间肯定更早。冠群蚂蚁可能起源于白垩纪早期甚至侏罗纪晚期,尽管这一假设还未得到古生物学证据的支持。.

Keywords: Antiquiformica alata; Formicidae; Formicinae; Kachin amber; Morphology; Paleontology; Taxonomy.

MeSH terms

  • Amber
  • Animals
  • Ants* / anatomy & histology
  • Ants* / classification
  • Ants* / physiology
  • Biological Evolution*
  • Fossils* / anatomy & histology
  • Male
  • Phylogeny

Substances

  • Amber

Grants and funding

This work was supported by the National Natural Science Foundation of China (32270467, 32020103006), National Research Foundation of Ukraine (2020/02/0369 to A.G.R.), and CONCYTEC through the PROCIENCIA “Interinstitutional Alliances for Doctorate Programs” (PE501084299-2023-PROCIENCIA-BM to M.S.E.)