Beetle Bites – Heteroceridae: the Variegated Mud

The superfamily Byrrhoidea contains a bunch of notable beetles, many of these being aquatic or semiaquatic. Now, a quick question: What is the best family of byrrhoids?

heteroWiki

That’s right: Heteroceridae! Sure, they’ve been described “phenotypical uniform” and “morphologically homogeneous.” And yes, they might be “virtually impossible” to reliably identify without deep expertize and “high-powered microscopes,” but just look at that little jerk.

Heterocerus parallelus

Heterocerus parallelus (Photo: K.V. Makarov – zin.ru)

How precious! At least he would be if his face weren’t so grotesquely prognathous. I’m not exactly sure what they do with those snouts; as far as I know, they just sort of rummage around wet, muddy shore habitats looking for seeds or other tidbits. I don’t think anybody really knows what heterocerids are up to, but that doesn’t stop them from being neat little critters.

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Heterocerus mollinus (Photo: Mike Quinn – bugguide.net)

Here’s what we do know:

They construct little tunnel systems underneath the surface of the mud with those big serrated front legs (fun fact: the German common name for these guys, Sägekäfer, means “saw beetle,” probably referring to those legs). Inside these tunnels, our variegated friends scurry about, make new friends by joining up with other heterocerid tunnels, hide from tiny digging grasshoppers, lay their eggs in tiny brood chambers, and generally live it up beetle-style.

I bet what you did today wasn’t that interesting, given that you’re currently reading about bugs on the Internet. What’s more, heterocerids are one of the few beetle lineages that live next to the ocean on purpose.

Tropicus

Tropicus pusillus (Photo: Mike Quinn – bugguide.net)

See, they’re not really all the same (besides, I saw a white one once). Remember to keep an eye out for heterocerids next time you’re next to a stream or lake or sewage pond. Just try to contain your excitement.

Notable characteristics: Dorsally flattened with spiny tibia, short, clubbed antenna; elytra shades of brown, solid or with lighter mottling.

Diversity: 250 species worldwide.

Heterocerus2

Heterocerus (Photo: Tom Murray – bugguide.net)

References:

  • Arnett, Ross H., et al., eds. American Beetles: Polyphaga: Scarabaeoidea through Curculionoidea. Vol. 2. CRC Press, 2002.
  • Aguilera, P., A. Mascagni, and I. Ribera. “The family Heteroceridae MacLeay, 1825 (Coleoptera, Dryopoidea) in the Iberian peninsula and the Balearic Islands.” Miscel· lània Zoològica 21.1 (1998): 75-100.

Beetle Bites – Nitidulidae: the Sap Loving/Hating Beetles

Niti1

Homepuraea amoena (Photo: S.E. Thorpe)

I like nitidulids; they’re an okay group of critters despite being members of the most confusing and convoluted groups in all of Coleoptera. They’re cute in the same awkward, bumbling way as the totally unrelated heterocerids.

Niti2

Cryptarcha concinna (Photo: Mike Quinn – bugguide.net)

Hetero1

Heterocerus sp. (Photo: Tom Murray – bugguide.net)

See, totally the same.

More strikingly, a few members of the subfamily Cillaeinae resemble tachyporine rove beetles to a preposterous degree. Same with these guys.

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Conotelus obscurus, a Nitidulid (Photo: Steve Nanz – bugguide.net)

tachyporine

Tachyporus jocosus, a staph (Photo: Mike Quinn – bugguide.net)

Unlike heterocerids, nitidulids are actually kind of important: some are pollinators of human food crops, others are agricultural pests of both live and stored plant products. One species, Glischrochilus quadrisignatus, apparently has a reputation for ruining picnics by suicidally diving into beverages, especially beer, which makes them one of the most strangely heinous beetle pests in existence (I have a crackpot theory that nitidulids are partially responsible for the inexplicable lids found on beer steins). A lot of nities also feed on fungi; next time you’re in the woods, take a peak under the nearest shelf mushroom and I bet you’ll find some of these guys.

Niti3

Glischrochilus quadrisignatus, the bane of picnics everywhere (Photo: Miroslav Deml)

There are species of nitidulids that eat practically everything: pollen, nectar, fruit, leaves. There are even a hand-full of carnivorous species. The one thing they don’t eat is sap. They hate the stuff, so there are no sap-eating species. Nope, not even one. Of course, there are a few that act like they enjoy sap, but it’s all just a clever ruse to fool would-be predators who would never think to look for them in sappy places. I’m onto your game, nitidulids.

In a particularly baffling case of unexpected consequences, an invasive species of nitidulid introduced in the US in the nineties, Aethina tumida, has become a major concern to beekeepers. They look harmless, right?

aethinaadult

Aethina tumida adult (Photo: James D. Ellis)

The adults sure do, but they aren’t the main concern for bee hives: the larva are the real terrors.

aethinalarva

Aethina tumida larva (Photo: James D. Ellis)

Gross.

More crackpot theories: I believe a particularly intrepid nitidulid, hoping to exploit the similarity between sap and honey, decided to take refuge inside a bee hive, only to discover that terrorizing bees was much more entertaining than being chased by predators all the time. If any creative and/or amoral entomologist is interested in coauthoring this paper with me, hit me up at beetlefacts@gmail.com.

If you’re curious about the evolution and systematics of this family, you’ll be happy to learn that they’re fairly well studied. This paper is a good starting point, but there are certainly many others worth looking at.

Notable characteristics: 3-segmented antennal club, transverse procoxal cavities, grooved metacoxa, and dilated tarsomeres (Arnett et al., 2002). Many (but certainly not all) are darkly colored with orange/pale mottling (also true of some Erotylidae).

Diversity: >4,000 species in over 200 genera.

References:

  • Arnett, Ross H., et al., eds. American Beetles: Polyphaga: Scarabaeoidea through Curculionoidea. Vol. 2. CRC Press, 2002.
  • Cline, Andrew R., et al. “Molecular phylogeny of Nitidulidae: assessment of subfamilial and tribal classification and formalization of the family Cybocephalidae (Coleoptera: Cucujoidea).” Systematic Entomology 39.4 (2014): 758-772.