Published online by Cambridge University Press: 20 May 2016
Pandorinellina? boucoti (Klapper) is based on material from the Lochkovian–Pragian (Devonian) section at Royal Creek, Yukon Territory, Canada, where it is found with species of the pesavis and sulcatus Zones. The species is also a rare element in the late Lochkovian–early Pragian faunas in the Toquima Range, central Nevada, where it is found within the same zones. Pandorinellina? boucoti has been recovered from 17 beds in sequence at the IK IV section in the McMonnigal Limestone and shows a morphologic change from a Pa element with a simple blade, small lateral lobes, and an enlarged triangular anterior denticle to a Pa element with ornamented pillars surmounting both platform lobes. The simple blade form is present in beds IK IV 21–16. The next overlying bed yields specimens with a single pillar-like enlargement of the larger platform lobe and a slight swelling on the smaller platform lobe. The following beds (IK IV 14–6) have only morphotypes with the pillar-like enlargement on both platform lobes.
This morphologic change effectively divides the upper pesavis Zone into two segments in the IK IV section. The rarity of this species, however, will probably limit the usefulness of the lineage in refined biostratigraphy and the sequence of morphotypes needs to be verified in other areas. Nevertheless, where present, P.? boucoti should improve the accuracy of correlation in the late Lochkovian and early Pragian.