English: Extant Opiliones and the Identification of a Fossil Stem Group

(A) Basal split between Cyphophthalmi (mite harvestmen) and Phalangida (all remaining harvestmen).

(B–G) Lateral view of adult Pettalus (B) with eye mounted on ozophore (arrow) and SEM magnification of the ozophore (C) showing the lateral eye (bottom) and dorsal ozopore (top). The open gonostome of the cyphophthalmid Metasiro with lateral flanges (arrowheads) is shown in ventral view (D). Eyes of Phalangida (E) are typically mounted on a centralized ocularium (F), and the gonostome is sealed with a hinged operculum (G).

(H–L) 3D reconstructions of Hastocularis argusgen. nov., sp. nov.

(H) Whole body and appendages.

(I) Lateral view of body and chelicerae showing ocularium (black arrow) and ozophores (white arrows).

(J) Right anterior region shows the ocularium (black arrow), ozophores (white arrows), and corresponding eyes (arrowheads).

(K) Left anterior region shows bilateral symmetry of ozophores and eyes.

(L) Intromittent genitalia (green) and open gonostome, with lateral flanges (orange).

(M) Schematic interpretation of intromittent genitalia.

ch, chelicera; g, gonostome; ig, intromittent genitalia; L1, first leg; pp, pedipalp. Scale bars represent 250 μm (G), 500 μm (L and M), 1 mm (J and K), 2 mm (I), and 4 mm (H).