Fig. 3

General morphology and surface ornamentation pattern of eggs of Huffmanela persica sp. nov. in various stages of development. A–H Photomicrographs and a–h corresponding line drawings of individual eggs at different stages of development (scale bars: 20 µm). A, a Eggs in stage I at very early stage, probably meiosis I, with a spherical nucleus in granular cytoplasm and incompletely developed chitinous layer and polar plugs (note early appearance of superficial projections of UL already apparent). B, b Eggs in stage II at later stage of development (probably meiosis II); chitin deposition appears to be complete. C, c Two-celled mitotic stage of early embryonic development (embryonated). D, d Later multicellular stage of embryonic development; chitinous layer still uniformly translucent with no apparent division into outer and inner chitinous layers. E, e Eggs in stage III with bean-like embryo and chitinous layer appearing two-layered under bright-field (light) microscopy with darker inner layer. F, f Tadpole-like embryos with UL appearing to have been partially dislodged from chitinous layer. G, g Eggs in stage IV with darker-brown shell; embryo now vermiform (larvated) and in-folded three times (pretzel stage). H, h Later stage IV egg with chitinous layer very dark brown; larva nearing final development and folded 5–6 times. I–T Photomicrographs of less developed (I–L), moderately developed (M–P) and fully developed (Q–T) eggs, where the first set of images (I, M, Q) represents overview of these variously advanced eggs, and the second (J, N, R), third (K, O, S) and fourth (L, P, T) series of images focus on the pattern of their surface ornamentation by adjusting the focal plane. Black and yellow arrows represent illusions of superficial ridges (well demonstrated in less developed eggs; occasionally appearing as interconnecting ridges, blue arrowhead) and sculptures on the egg surface, respectively. Green arrowheads exhibit irregular protuberances on the eggshell surface. Red arrowheads indicate an illusory spinous appearance in fully developed eggs