Azygosporogenesis in Mucor azygosporus

Abstract

Light microscopic and scanning and transmission electron microscopic observations were obtained on azygosporogenesis in Mucor azygosporus Benjamin. Terminal gametangia are delimited by centripetally growing septa but plasmodesmata maintain cytoplasmic continuity between the azygophores and gametangia. Warts develop as regularly spaced patches of electron-opaque wall material on, and ultimately within, the inner primary wall. The mature complex azygosporangium wall is composed of (1) remnants of the membranous outer primary wall, (2) the ornamented layer of electron-opaque, stellate, confluent warts, and (3) a fibrillar, electron-opaque, tertiary layer. A homogeneous, hyaline azygospore wall (quaternary layer or endospore) with stellate warts is laid down within the azygosporangium. A comparison of the fine structural aspects of zygosporogenesis and azygosporogenesis in the Mucorales is presented.

An unusual specimen of the enigmatic fungal reproductive unit Windipila spinifera from the Lower Devonian Rhynie cherts of Scotland

“…2) containing single zygospores (zsp in Fig. 2) following gametangial fusion, and sometimes azygosporangia containing azygospores, which are similar to zygospores but form parthenogenetically without gametangial fusion (e.g., Benjamin and Mehrotra 1963;O'Donnell et al 1977). The zygosporangium wall eventually ruptures and the zygospore germinates.…”

Morphology and ontogenetic development of Zwergimyces vestitus, a fungal reproductive unit enveloped in a hyphal mantle from the Lower Devonian Rhynie chert

“…Although we interpret this inflation as a structural deformity or preservation artifact because it has only been observed in a single specimen, we cannot completely rule out the possibility that it represents a gametangium giving rise to a zygosporangium or azygosporangium (e.g., O'Donnell et al, 1977;Benjamin, 1979;Wagner et al, 2013), or a large bulbous base subtending a gigasporoid glomeromycotan spore (e.g., Khade, 2011;Oehl et al, 2011;Redecker and Schüßler, 2014). Somewhat similar to the inflated subtending hypha shown in Pl.…”