Schizaraeus fouquei sp. nov., the first record of Schizaraeus from Peru (Coleoptera: Tenebrionidae: Stenosini)

A new species of Stenosini (Coleoptera: Tenebrionidae: Pimeliinae), Schizaraeus fouquei sp. nov. is described from southern Andes of Peru: Apurímac and Cusco regions. Prior to this study, Schizaraeus Kulzer, 1955 was monotypic with one species, S. acuticosta Kulzer, 1955 from Catamarca Province in Argentina. We present habitus photographs of both species, scanning electron micrographs of external morphology of the new species, a distribution map, and a comparison of the characters of both species of the genus.

First archaeointensity reference paleosecular variation curve for South America and its implications for geomagnetism and archaeology

We report comprehensive rock-magnetic and archaeointensity investigations from 21 well-constrained pottery fragments from the Catamarca province of northwest Argentina. The absolute ages of the studied sites are ascertained by several high-quality radiometric ages and range between 1940 to 114014C yr BP. Magnetic mineralogy experiments indicates that the remanence is carried by thermally stable Ti-poor titanomagnetites. Forty-seven samples belonging to 11 out of 98 studied potsherds yielded reliable absolute intensity determinations judging from the quality parameters associated with the Thellier double-heating experiments. Moreover, we analyzed the available absolute geomagnetic intensities associated with the radiometric ages to construct the first intensity paleosecular variation curve (PSVC) for South America using thermoremanent magnetization carried by burned archaeological artifacts obtained in the present investigation and 79 other selected archaeointensities (out of 213 published in the literature). The dataset is used to build the PSVC reference curve by combined bootstrap and temporal P-spline methods. The variation curve shows significant differences with the global prediction model SHA.DIF.14k mainly based on the GEOMAGIA database. This intensity PSVC curve shows reasonably good agreement with paleosecular variation curves for Europe between 850 through 1150 BC and for Asia between 1000 and 1500 BC. This regional curve may be used as most reliable archaeomagnetic dating tool for the major part of South America (Peru, Brazil, Argentina, Chile, and Bolivia) for the last two millennia.

Tachymenis peruviana Wiegmann, 1834 (Serpentes, Dipsadidae) in Argentina: geographic distribution and a new province record

Tachymenis peruviana Wiegmann, 1834 (Serpentes, Dipsadidae) is known from Peru, Bolivia, northern Chile and northwestern Argentina. In northwestern Argentina, the species is distributed from Jujuy to Catamarca province. In this study, we present the accurate distribution of the species in Argentina and the first records from La Rioja province, at 2000 and 3000 m a.s.l. in the Famatina region, extending the known distribution to the southwest.

Omariniite, Cu8Fe2ZnGe2S12, the germanium analogue of stannoidite, a new mineral species from Capillitas, Argentina

Omariniite, ideally Cu8Fe2ZnGe2S12, represents the Ge-analogue of stannoidite and was found in bornite-chalcocite-rich ores near the La Rosario vein of the Capillitas epithermal deposit, Catamarca Province, Argentina. The mineral is associated closely with three other Ge-bearing minerals (putzite, catamarcaite, rarely zincobriartite) and bornite, chalcocite, digenite, covellite, sphalerite, tennantite, luzonite, wittichenite, thalcusite and traces of mawsonite. The width of the seams rarely exceeds 60 μm, their length can attain several 100 μm. The mineral is opaque, orange-brown in polished section, has a metallic lustre and a brownish-black streak. It is brittle, and the fracture is irregular to subconchoidal. Neither cleavage nor parting are observable in the sections. In plane-polarized light omariniite is brownish-orange and has a weak pleochroism. Internal reflections are absent. The mineral is distinctly anisotropic with rotation tints varying between brownish-orange and greenish-brown. The average result of 45 electron-microprobe analyses is Cu 42.18(34), Fe 9.37(26), Zn 5.17(43), In 0.20(6), Ge 11.62(22), S 31.80(20), total 100.34(46) wt.%. The empirical formula, based on Σ(Me + S) = 25, is Cu8.04(Fe2.03In0.02)Σ2.05Zn0.96 Ge1.94S12.01, ideally Cu8+Fe2+Zn2+Ge24+S122-. Omariniite is orthorhombic, space group I222, with unit-cell parameters: a = 10.774(1), b = 5.3921(5), c = 16.085(2) Å, V = 934.5(2) Å3, a:b:c = 1.9981:1:2.9831, Z = 2. X-ray single-crystal studies (R1 = 0.023) revealed the structure to be a sphalerite derivative identical to that of stannoidite. Omariniite is named after Dr. Ricardo Héctor Omarini (1946–2015), Professor at the University of Salta, for his numerous contributions to the geology of Argentina.