Monday, June 24, 2013

Vicente Flat 2.) What Dwells on the Forest's Floor

      By the time we arrived to our desired spot the sun was well on its way down. We were exhausted and hungry. We started the fire and then took shifts of monitoring it while a given number of us four would visit the steam to wash up after such a warm hike down into the canyon. While eating my re-hydrated dinner, I was thinking about the beetles I might see that night on the forest floor. Most of all, I was hoping to find the subgenus Brennus (Carabidae: Scaphinotus). This subgenus has 15 species; 14 of which occur in California (with S. johnsoni restricted to the Olympic Mountains in Washington), with 10 to as many as 12 of them endemic to California. Six of these are represented in my collection, though I hope to collect more in the coming years.

These impresive Sequoias and the nearby stream indicate
an excellent habitat for unique California ground beetles.

At about 10 pm I finished my meal, picked up my flashlight and proceeded to engage in my favorite collecting technique in forests. Immediately my light revealed two specimens of Scaphinotus (Brennus) cordatus (LeConte). If I were using my head, I would have collected one before preceding to photograph the other, but this wasn't the case. In my excitement I knelt down and started gearing my camera for night photography. Consequently, one ran into the newly discovered poison oak meadow which was to either side of the trail. After all of this, the pictures didn't turn out well anyway. Oh well.

Scaphinotus (Brennus) cordatus (LeConte)

There were another two Brennus species that I found that night; S. B. interruptus and S. B. striatopunctatus. The former I collected four specimens of, which now represent that species in my collection, and the latter two specimens, which now rest next to the Sun Luis Obispo localities I have from June of 2012. I didn't attempt to photograph any more of the Scaphinotus until they were pinned at home in the collection.

Scaphinotus (Brennus) interruptus (Menetries)

Scaphinotus (Brennus) striatopunctatus (Chaudoir)

The fact that I found a total of eight specimens all within the poison oak bordered section of the trail makes me wonder if this was coincidence. In the more open area with less grass and more distant poison oak just 20 ft. away I found none.



Soon after this I found another geographically unique Carabid; Omus c. californicus. While the genus Omus is still under study, the current revision by Mont Cazier distinguishes five different species; O. audouini, O. californicus, O. dejeani, O. cazieri and O. submetallicus. In my reasoning, four of these are justified as independent species, while the now "O. californicus" certainly includes several other distinct species. According to Dennis Haines, there are over 100 previously described species that are now lumped under O. californicus. Yes, most of these shouldn't have a species-level status, but surely more than one does. One of the agreed upon independent species includes the Sierra Nevada endemic Smooth Night-stalking Tiger Beetle, O. laevis which I will be featuring on this blog in a matter of a few weeks. As far as this Vicente Flat species, the title O. c. californicus will have to do for now.

O. c. californicus Eschscholtz

I did fight a little longer for a field shot of this guy. Omus are seldom photographed in the wild, and with such an interesting and restricted genus, I wouldn't give up easily. I found a strip of bark and placed it in the path of this aware and on the move ground beetle. After a couple attempts the beast trusted the shelter to linger underneath, so after 30 seconds I slowly removed it and tried to make my precious time worth while as it would soon be in the move again. Eventually, after repeating this technique several times, I got the shot fit to my satisfaction. (If you're looking for a challenging subject of macro photography, try ground and tiger beetles!).

Somewhere around the time of collecting these critters, I stumbled upon a third subfamily of ground beetles; Paussinae! This uncommon subfamily with many myrmecophiles are poorly represented in the North America, but this especially bizarre species, Metrius contractus, has made it's home in our very own Pacific northwest.

Metrius contractus Eschscholtz

It may not look like much, but if you do a search for it's relatives, you might be surprised at the appearance of others from this subfamily. It's genetics are something else. I have had the privilege to see this species abundantly through my time in California. The only other species in this genus is M. explodens from Idaho. (It's too bad the picture didn't turn out so nicely).

The last buggy discovery of the night was a totally different kind of beetle, but is was almost as interesting:

Odonteus obesus LeConte
Male

Two years ago I collected my first and only other individual of this species (Geotrupidae: Bolboceratinae). In that instance it was a female, so it was nice to collect a complimentary male. The horns on it's pronotum and head are quite impressive for this scarab's size. The photo was enlarged for this reason.

I will be blogging the third and final section of this hike next week.

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