Leptoplectron Reichenbach 1850. (1 Viewer)

I came across this apparent anomaly whilst editing the HBWAlive Key. The genus Leptoplectron is illustrated by Reichenbach 1850, Avium Systema Naturale. Das natürliche System der Vögel, on plate LXXV (top middle figs.), but no species are indicated. Cabanis 1851, Museum Heineanum, I, Singvögel, p. 127, synonymized Leptoplectron with Centrophanes (= Calcarius, type C. lapponicus). Whilst Reichenbach's plate shows the long slender hind-claw (hence Leptoplectron), I am at a loss to identify the bird represented by the head and bill illustrated there. It appears to be some sort of finch/bunting/American sparrow, but I have yet to put a name to it. It is certainly not a Lapland Bunting C. lapponicus. Do BirdForum members have any suggestions as to the identity of Reichenbach's bird - or have I missed something?

Here ... could it be badly drawn Smith's Longspur Calcarius pictus ... !?

Compare with the plate of Swainson's "Emberiza (Plectrophanes) picta", of 1831 (here, on the Plate only "Plectrophanes picta") a k a "Painted Lark Bunting", by Audubon in 1840 (here) ... ? Also compare how Reed depicted the same Longspur in 1915 (here).
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The bird is a male Smith's Longspur Calcarius pictus (Sw. 1832).
(This was perhaps first noted in press by Bonaparte in 1857 [here]. Cabanis 1851 [here] presumably had this in mind too, but didn't write it.)

Björn and Laurent, thank you both very much indeed for your inputs and attachments - reliable as ever! As you remark, Reichenbach's plate doesn't show the complete pattern of the head of Smith's Longspur Calcarius pictus, but your suggestions, and Prince Bonaparte's 1857 words, clinch the identity of Leptoplectron. I have also revisited Cabanis 1851, where he also includes Emberiza picta Sws., Plectrophanes ornata Towns., and Plectrophanes Smithi Audub. in Centrophanes. I have edited the Key accordingly.