A new discovery in the Hawaiian web of life

The Hawaiian islands are connected, not only geologically, but with an intricate web of life.

This fact has been reestablished in the past week with the announcement of the discovery of a series of closely related moths on three islands of the Northwestern Hawaiian Islands—moths that have been evolving in the Islands for 30 million years.

(Image: The eight new species of moths from the Papahanaumokuakea Marine National Monument. Source: NOAA.)

The moths are new to science, but this kind of connectivity is not.

In the wet forests of the Island, the alani or melicope species are an example. The various species are clearly related, even to an untrained eye. They tend to have large waxy leaves that form a fat oval. They tend to be leggy. Small, delicate flowers.

They are very much the same in many ways. And different.

A Kaua'i species, mokihana, has the famous anise scent, which the other species lack. The four-parted seed pods are tightly closed in some species, but the seed cases spread out like petals on a bloom in others.

There are the cave spiders, hunting spiders with less-developed eyes on the older islands than on the younger ones.

And forest birds with different colors and food preferences on different islands, but otherwise clearly closely related.

On and on. Cousins of a Molokai bug live on Kaua'i alongside bird cousins, plant cousins and so forth.

Perhaps what's most surprising about the new moths is that they have survived long enough to be found, not that they ever existed.

Reseachers Patrick Schmitz and Daniel Rubinoff announced their find in the journal Zootaxa: eight new members of the moth genus Hyposmocoma, all found within islands of the Papahanaumokuakea Marine National Monument.

The genus Hyposmocoma is unique to Hawai'i, but the group is well represented here, with more than 300 species, most of them on the major islands, and one previously known from the northwestern islands—from Necker or Mokumanamana. Some species are from the wet forest, some from aquatic habitats, and the new finds suggest that species have also evolved to handle very arid habitats of the low northwestern islands.

A monument press release included these quotations:

“This is a great snapshot of species endemism, one that indicates how species have evolved on islands throughout the whole archipelago over time,” said Rubinoff. “We are continuing our research now, but it is possible that the ancient ancestor of the now uniquely Hawaiian Hyposmocoma moths may have landed on a young Northwestern Hawaiian Island and evolved over millions of years into several lineages, which hopped down the island chain, spawning a diversity of species.”

“Although only a few of the lineages that were once on the Northwestern Hawaiian Islands are still holding on there now, these tiny atolls, in a former life, were the crucibles of one of the most diverse groups on the current High Islands. The species we described from the Northwestern Hawaiian Islands are the descendents of those original, and likely ancient, Hyposmocoma lineages and they have hung on, adapting over time to the islands’ current severe dry conditions. They are the survivors.”

“I am certain more species are waiting to be discovered in the Monument, since we’ve found hard evidence of their caterpillars and know them to be unique,” said Rubinoff. “We also know that Gardner Pinnacles has at least one endemic species and possibly more, but we just haven’t been able to get there yet to document it.”

Among the ways these creatures are distinguished from each other, besides their unique wing coloring, is that their larval cases have very different shapes.

The new species are:

• Hyposmocoma laysanensis, named after and found only on Laysan Island

• Hyposmocoma ekemamao, a larger species found only on Laysan Island and named for its purselike case (eke in Hawaiian) and the island’s remoteness (mamao in Hawaiian)

• Hyposmocoma opuumaloo, found only on Mokumanamana and named from the Hawaiian opu‘u, cone, and malo‘o, dry, referring to its cone-shaped case and the island’s dry habitat (most cone-cased species in the Main Hawaiian Islands are aquatic)

• Hyposmocoma mokumana, found on Mokumanamana and named for the island

• Hyposmocoma nihoa, found on Nihoa and named for the island

• Hyposmocoma kikokolu, found on Nihoa and named from the Hawaiian kiko, spot, and kolu, three, referring to the three spots on its forewing

• Hyposmocoma menehune, found on Nihoa and named for the nocturnal Hawaiian legendary menehune

• Hyposmocoma papahanau, found on Nihoa and named after Papahanaumokuakea


© Jan TenBruggencate 2009