In a first, scientist discovers fossilized cockroach sperm in 30-million-year-old amber

The newly-identified specimen is the only cockroach of its variety, ectocbiid, to be discovered in amber from the Dominican Republic.
Deena Theresa
Supella dominicana.
Supella dominicana.

George Poinar Jr 

An Oregon State University scientist has identified a new cockroach species fossilized in Dominican amber. That's not it. It's also the first fossil cockroach to be found with sperm cells.

"It is well preserved with a yellow cross bar across the wings and a central, vertical, yellow stripe that appears to divide the body into two parts," George Poinar Jr., professor emeritus in the OSU College of Science, said in a statement.

The 30-million-year-old specimen is the only cockroach of its variety, ectocbiid, to be discovered in amber from the Dominican Republic. Which is interesting as it has no living descendants in the Dominican or West Indies. 

"It has long spines, used for defense, on its legs, especially the hind legs. Also of interest is the sperm bundle containing spermatozoa with dark acrosomes, structures covering the head of the sperm, since fossil sperm are rare," Poinar said.

Poinar's findings were published in the journal Biologica this month.

In a first, scientist discovers fossilized cockroach sperm in 30-million-year-old amber
Supella dominicana.

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It is a known fact that cockroaches are the world's oldest pests. Their extraordinary resilience helps them survive in temperatures below freezing, and can even withstand pressures of up to 900 times their body weight, said Poinar.

There are more than 4,000 species of roaches crawling all over the Earth. Fortunately, only 30 types of those share a 'home' with humans. Unfortunately, all of them are considered pests.

“So what caused these cockroaches to become extinct when it is so difficult to get rid of them today?” wondered Poinar.

Because they don't care about walking through sewage or decaying matter, Poinar stated that roaches are likely to contaminate the surfaces they touch. 

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"They are considered medically important insects since they are carriers of human pathogens, including bacteria that cause salmonella, staphylococcus, and streptococcus," Poinar said. "They also harbor viruses. And in addition to spreading pathogens and causing allergic reactions, just their presence is very unsettling."

Cockroaches also contain enzymes that protect their toxic substances. This is one of the reasons they cannot be easily evicted. There's also evidence that they're developing resistance to many insecticides. Oh, the horror.

"The difficulty in eliminating them from homes once they’ve taken up residence can cause a lot of stress," Poinar said. "Many might say that the best place for a cockroach is entombed in amber."

The new cockroach species is the latest of the many scientific discoveries made by Poinar,  who is an international expert in using plant and animal life forms preserved in amber to learn about the biology and ecology of the distant past.

Study Abstract:

A small, male cockroach (7 mm in length) in Dominican amber is described as Supella dominicana sp. n. (Blattida: Ectobiidae = Blattellidae). The dark tegmina, which are equal to the length of the abdomen, have a yellow cross bar and a central stripe giving the illusion that the body is divided into two halves. The pronotum is partially triangular in outline, with rounded edges and unusually flat surface. The fore femora contain two short apical terminal spines and a series of short wide-spaced marginal spines. The fore tarsus has the first article surpassing the others combined. The 7-segmented cerci are longer than wide. The arolia are well developed and the tarsal claws are symmetrical, of equal length, each with a blunt tooth. The two styles are small, equal in shape and with a branched seta. Developing spermatids are present at the tip of the abdomen. This fossil, which is the first ectobiid cockroach described from Dominican amber, provides some new features of the genus Supella Shelford, 1911.