FIGURE 1. Myrmecium fuscum Dahl, 1907 in Myrmecium colombianum (Poinar, 2024) n. comb.-the second known fossilized castianeirine spider, illustration of a further specimen of Myrmecium in Colombian copal and notes on transformational ant mimicry and evolution of the genus

FIGURE 1. Myrmecium fuscum Dahl, 1907, female, Chairo, La Paz Department, Bolivia: A. Lateral view, arrow indicates the large hump over leg IV insertion which is characteristic of the species group; B. Dorsal view, arrows indicate the three deep lateral carapace constrictions, diagnostic feature for the genus; scale bars 1 mm. C. Dorsal habitus of minor worker of Crematogaster sp., possible model of juvenile Myrmecium sp., Villa Tunari, Bolivia. D. Dorsal habitus of juvenile of Myrmecium sp. in Colombian copal (no further information available; photo source: FossilEra (2024), copyright Matt Heaton). Ontogenetic transformation in Myrmecium bifasciatum Taczanowski, 1874, Villa Tunari, Bolivia: E. Dorsal habitus of juvenile, length between 2–3 mm, recently hatched from the egg sac, the abdomen becomes more Crematogaster-like (teardrop-shaped) after feeding; F. Dorsal habitus of mother, length about 7 mm.