The D-Rex Giant Fungus Quiz: Six Questions

Somewhere in the forests of Yunnan Province, a fungus is growing taller than your forearm. Scientists from China, Thailand, and Mexico have formally described Dianjunus rex, nicknamed D-rex, a fungal giant whose upright fruiting bodies climb to 50 centimeters tall and weigh up to 2.2 kilograms. Those measurements make it the largest ever documented in the phylum Ascomycota, a group that holds more than sixty-four thousand species, from morels and truffles to the molds on old bread. Welcome to the giant fungus quiz.

D-rex earned more than a new species name. The researchers placed it in its own brand-new genus, Dianjunus, and a whole new family, Dianjunaceae, inside the order Xylariales. The name Dianjunus means King of Dian, a nod to an ancient Chinese kingdom. Genome-based dating suggests the Dianjunaceae lineage split off about 65 million years ago, in the aftermath of the asteroid impact that ended the reign of the dinosaurs, when dead wood everywhere created fresh opportunities for wood-decomposing fungi. New families are rare events in mycology, which makes D-rex a genuine oddity, and a perfect subject for a giant fungus quiz.

The specimens turned up during surveys of three very different Yunnan habitats: tropical rainforest in the Xishuangbanna region and temperate coniferous forests near Kunming and Lufeng. Collectors spotted pale, finger-like structures pushing out of the roots of dying Chinese cork oaks, covered in a powdery whitish-yellow fibrous layer that darkened as the specimens aged. The biggest find was bilobed, like two fused fingers, and it tipped the field scale at the record weight. The study was published September 29 in Frontiers in Fungal Biology, according to a report from Frontiers, with Dr. Indunil C. Senanayake of the Kunming Institute of Botany as corresponding author, and the field photographs alone are worth a look. Senanayake said in the report that the species offers "a rare window into the evolution of extreme fungal body forms" and that the find shows how much fungal biodiversity remains undiscovered in East Asian forests.

The tall shape may not be an accident. According to Phys.org's account of the research, the team speculates that towering fruiting bodies help D-rex launch its spores on the wind through dense forest, where a ground-hugging fungus would struggle to spread. Whatever the reason, the previous Ascomycota record holder, Engleromyces goetzei, a bamboo-dwelling fungus from Kenya with a body about 30 centimeters across and roughly 3.2 kilograms in a two-lobed mass, has officially been dethroned. Time to see what stuck. This giant fungus quiz has six questions, four options each, and the answers at the bottom. No peeking.

The questions

One point per correct answer, bragging rights at stake. On with the giant fungus quiz.

Question one. How tall can D-rex's fruiting bodies grow?

A. Twenty centimeters
B. Thirty centimeters
C. Fifty centimeters
D. One meter

Question two. What makes D-rex taxonomically special?

A. It is the first fungus ever found in China
B. It is a whole new genus and family, not just a new species
C. It glows in the dark like a lantern
D. It was found growing on a meteorite

Question three. Where did scientists discover D-rex?

A. The Amazon rainforest
B. The forests of Yunnan Province, China
C. The highlands of Kenya
D. The peat swamps of Borneo

Question four. Roughly how old is the Dianjunaceae lineage?

A. Ten thousand years
B. Six hundred thousand years
C. Sixty-five million years
D. One billion years

Question five. In which fungal phylum does D-rex hold the size record?

A. Basidiomycota
B. Ascomycota
C. Chytridiomycota
D. Mucoromycota

Question six. Before D-rex, which fungus held the Ascomycota size record?

A. Cordyceps militaris
B. Tuber melanosporum
C. Engleromyces goetzei
D. Morchella esculenta

The answers

Here are the giant fungus quiz answers, with the science behind each one.

One: C. D-rex fruiting bodies reach up to fifty centimeters, about twenty inches, the tallest known in Ascomycota.

Two: B. The team described a new genus, Dianjunus, and a new family, Dianjunaceae, within the order Xylariales. That is two full ranks above a species, and it almost never happens.

Three: B. The specimens came from three Yunnan habitats: tropical rainforest in Xishuangbanna and coniferous forests near Kunming and Lufeng, growing out of the roots of Chinese cork oaks.

Four: C. Dating puts the family's origin around sixty-five million years ago, right after the Cretaceous-Paleogene extinction that wiped out the non-avian dinosaurs and opened up new niches for wood-decomposing fungi.

Five: B. D-rex is an ascomycete. Members of this phylum release spores from tiny sac-like structures instead of growing true mushrooms, which makes a half-meter fruiting body genuinely strange.

Six: C. Engleromyces goetzei, which grows on bamboo culms in Kenya, held the previous record with bodies about thirty centimeters across. D-rex beat it on height, and the record books have been rewritten.

How did you score on the giant fungus quiz? Four or more correct and you are officially fungus-literate. Fewer than that, and D-rex has earned its intimidation factor. If this giant fungus quiz left you wanting more, the exoplanet aurora quiz and the Nobel Peace Prize quiz and the Ireland strike quiz are all waiting. Somewhere out there in Yunnan, something the size of a toddler is quietly digesting a tree root, and now you know its name. Not bad for a giant fungus quiz about a mushroom that is not even a mushroom.