World’s First Amber-Preserved Arachnid Penis Found

Amber-Preserved Arachnid Penis
For the first time, an arachnid's genitalia was found fully extended within ancient amber. Photo by Museum für Naturkunde

BERLIN, Feb. 3 (UPI) — A 99 million-year-old harvestman with an extended penis has been found preserved in a piece of amber. It’s the first time the arachnid’s penis has found clearly visible in ancient hardened sap.

The scientific literature features the descriptions of some 6,600 harvestman species, but only 38 of them have been described from fossils. The latest fossil is one of them, a Halitherses grimaldii specimen.

First discovered and described in 2005, Halitherses grimaldii proved difficult to properly position within the harvestman family tree. The latest specimen — found in an ancient chunk of Burmese amber collected in Myanmar — has helped scientists do just that.

An arachnid’s genitalia is extremely helpful in identifying and placing various species within the familial lineage.

Not only is the arachnid’s penis extremely fragile, it is also typically hidden away inside the creature’s body when not in use. But for the first time, an arachnid penis was preserved fully extended — proof that ancient harvestman species of the Cretaceous period mated the same way their modern relatives do.

In the journal The Science of Nature, researchers from the Museum für Naturkunde in Berlin described the arachnid’s penis as having “a slender, distally flattened truncus, a spatulate heart-shaped glans and a short distal stylus, twisted at the tip.”

Researchers were also intrigued by the harvestman’s uniquely large eyes, which they suspect are a leftover primitive feature from earlier relatives. The combination of features — some primitive, some more modern — moved scientists to classify the species in a new extinct family Halithersidae, within the suborder Dyspnoi.

“This is the first time that a fossil family has been defined using a mixture of features relating to both the body and the genitalia,” researchers explained in a press release, “and allowed the researchers to study the relationships of these ancient fossils using the same approaches that they would use for living species.”


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