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Cafius seminitens

Cafius seminitens
Ano Nuevo State Reserve, San Mateo County, California, USA
September 20, 2009
The first couplet of the key in Orth & Moore uses to the distinctive "cowlick" pubescence of the abdominal tergites in the two species C. seminitens and C. canescens to separate them out from the remaining eight species. The detail view here shows this "cowlick" pubescence.

The second couplet states that C. seminitens can be distinguished by its having denser pubescence on the last two sternites than on the preceding sternites. Note that sternites can't be seen in my dorsal image here. Nevertheless, in their detailed descriptions for seminitens and canescens, Orth & Moore emphasize another distinctive character difference. Namely, the first few tergites of seminitens have "wavy" acrocostal sutures, whereas those of canescens have straight acrocostal sutures. I'd say the the first few acrocostal sutures are wavy here. This is consistent with the top two figures in Orth & Moore, showing seminitens on the left and canescens on the right. [Note: I couldn't find a definition of "acrocostal sutures", but I presume the term refers to the posterior edges of the tergites..."acro" = top, and "costal" = rib.]

In meticulously comparing the very detailed description of C. seminitens in Orth & Moore line-by-line with the specimen in my photos, I was delighted to see how seamlessly it seemed to fit...until I got to "Apical margin of 6th sternite with a triangular emargination as deep as wide". At that point I thought, "Uh oh...there's no notch at the end of the 6th sternite in my photo." But then, reading a few sentences further, the authors clearly state that it's just males that have such a notch...whereas females have "Apical margin of 6th sternite entire." Thus, I thought all was well...and concluded this is a female. Only later did I realize (thanks to v. belov's comment below) that I had been inadvertently misreading sternite as tergite the whole time! Thus, since my dorsal image only shows tergites...and I don't have a ventral image...these points were moot. (And now you see the reason for all the somewhat distracting use of bold emphasis above!)

[Note: The tip of the 6th tergite in the drawing of seminitens in Orth & Moore is shown as notched, whereas it's entire on the beetle imaged here. I'm speculating that the notching of the 6th tergite might match with the notching of the 6th sternite, which is given as a character for the male of seminitens. If so, as the tip of the 6th tergite here is entire, perhaps that indicates is a female.]

Images of this individual: tag all
Cafius seminitens Cafius seminitens Cafius seminitens

Moved from Cafius.

Moved from Cafius.

this photo does not show any sternites -- must be a mixup

Yikes...sloppy error on my part!
Good point =v=...thanks for the correction!!

I meant tergite (= a dorsal sclerite of an abdominal segment)...and not sternite (= a ventral sclerite of an abdominal segment)!! After the first instance of the word "tergite" in the Orth & Moore key, I apparently didn't read carefully enough and (simple-mindedly!) equated all the subsequent occurences of the word "sternite" with "tergite". Oops! (You see, I am an amateur...QED :-)

Well, on review of the key and descriptions, at least I think the species determination of C. seminitens still survives my error in confounding the two terms. But my gender assessment doesn't necessarily hold.

Details supporting above statement follow...

The 1st couplet of the key does indeed refer to "cowlick pubescence" of the no problem there. However, the 2nd couplet, separating C. seminitens and C. canescens refers to the "twice as dense pubescence" of the last two sternites for seminitens. Likewise, the determination of gender refers to the apical tip of the last sternite...notched for males, entire for females. However, the remarks made under "Notes" in the descriptions of seminitens and canescens emphasize that seminitens can be distinguished by the "wavy acrocostal sutures" of its that still points to this being seminitens. (Seems I lucked out and am perhaps partially redeemed :-)

Thanks again for catching this and pointing it out =v=. I'll have to examine the last two sternites when I see these guys in the future. And also...try to pay more attention to all the syllables in words! :-)

PS: I'll edit the text of my posts here to correct my error...which may make these comments initially confusing for subsequent readers...oh well!)

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