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The Nucras of the eastern Zambezi River basin region, comprising Zambia, Malawi and central Mozambique have been poorly studied. We re-evaluated the type specimens of Lacerta cameranoi Bedriaga, 1886 and L. tessellata pseudotessellata Bedriaga, 1886, both collected at Tete, Mozambique by Wilhelm Peters in the 1840s. Both are assignable to N. ornata, the most widespread Nucras in the region. However, an additional specimen collected from Tete is referrable to N. holubi, filling a collecting gap for this species between central Zimbabwe and southern Malawi. Nucras records from northeastern Zambia include several N. boulengeri, two photo-vouchered records, one unidentifiable and the other an enigmatic form not consistent with any known species, and a new species from Senga Hill, Northern Province. The new species, Nucras margaritae sp. nov., is known only from its holotype. It is morphologically similar to N. ornata, from which it is separated by 620 airline km, but is deeply genetically divergent from all congeners and is sister to the clade comprising N. holubi, N. ornata, N. damarana and N. intertexta. At least five species of Nucras, four currently named, inhabit the greater eastern Zambezi River basin.   

Abstract Among squamates, hemipenes are known to evolve rapidly and exhibit diverse shapes, sizes, and ornamentation. Croaking geckos (Aristelliger) are unique among geckos in exhibiting mineralized structures (hemibacula) in their hemipenes. We here describe the gross morphology of the hemibacula of each currently recognized species ofAristelliger, document hemibacular histology, and report on hemibaculum development. We confirm the presence of hemibacula in all currently recognized species and demonstrate that three distinct morphologies correspond to three putative clades in the genus. Histology revealed that hemibacula are superficially similar to chondroid bone and composed of mineralized dense connective tissue covered in a thin layer of epidermis with alcian‐positive cells embedded within a mineralized matrix. Additionally, we demonstrate that hemibacula do not develop until past the onset of sexual maturity and that hemibaculum length scales isometrically with body size. We hypothesize that hemibacula ofAristelligerdevelop via peramorphosis, a phenomenon also expressed in the cranial morphology of this genus. Additionally, we speculate on the functional significance of these enigmatic structures. 

The genus Rhoptropus comprises nine recognized species of diurnal geckos endemic to the arid regions of Angola and Namibia. Seven species occur in Angola, including the widespread R. boultoni and the poorly known Angolan endemics R. benguellensis and R. montanus, formerly recognized as subspecies of R. boultoni. While R. benguellensis is relatively widespread in the Angolan Escarpment highlands, R. montanus is geographically restricted to the Huíla Plateau. Recent fieldwork on the Serra da Neve inselberg, a herpetological diversity hotspot in southwestern Angola, revealed the presence of an undescribed species of Rhoptropus at an elevation of approximately 1600 m. An integrative taxonomic approach combining coloration, morphological and molecular data supports the recognition of this population as a distinct taxonomic unit with affinities to R. montanus, which we describe herein as Rhoptropus nivimontanus sp. nov. The discovery of a new species of Rhoptropus endemic to Serra da Neve is discussed in the biogeographic context of the region.  

Conventional refractive microscope objective lenses have limited applicability to a range of imaging modalities due to the dispersive nature of their optical elements. Designing a conventional refractive microscope objective that provides well-corrected imaging over a broad spectral range can be challenging, if not impossible. In contrast, reflective optics are inherently achromatic, so a system composed entirely of reflective elements is free from chromatic aberrations and, as a result, can image over an ultra-wide spectral range with perfect color correction. This study explores the design space of unobscured high numerical aperture, all-reflective microscope objectives. In particular, using freeform optical elements we obviate the need for a center obscuration, rendering the objective’s modulation transfer function comparable to that of refractive lens systems of similar numerical aperture. We detail the design process of the reflective objective, from determining the design specifications to the system optimization and sensitivity analysis. The outcome is an all-reflective freeform microscope objective lens with a 0.65 numerical aperture that provides diffraction-limited imaging and is compatible with the geometric constraints of commercial microscope systems. 

Reimaging telescopes have an accessible exit pupil that facilitates stray light mitigation and matching to auxiliary optical systems. Freeform surfaces present the opportunity for unobscured reflective systems to be folded into geometries that are otherwise impracticable with conventional surface types. It is critical, however, to understand the limitations of the enabled folding geometries and choose the one that best balances the optical performance and mechanical requirements. Here, we used the aberration theory of freeform surfaces to determine the aberration correction potential for using freeform surfaces in reimaging three-mirror telescopes and established a hierarchy for the different folding geometries without using optimization. We found that when using freeform optics, the ideal folding geometry had 9× better wavefront performance compared to the next best geometry. Within that ideal geometry, the system using freeform optics had 39% better wavefront performance compared to a system using off-axis asphere surfaces, thus quantifying one of the advantages of freeform optics in this design space. 

Afocal telescopes are often used as foreoptics to existing imaging systems. Here, we discuss some unique aspects of designing afocal systems and detail various afocal design studies we performed using freeform optics. 

Four species of the genusPanaspis–P. cabindae,P. wahlbergi,P. maculicollisandP. mocamedensis– are currently known from Angola. The analysis of recently collected specimens from Serra da Neve Inselberg, an isolated mountain located in northern Namibe Province, revealed unexpected taxonomic diversity in the group. Using an integrative taxonomy approach based on morphological and DNA sequence data, with both mitochondrial (16S) and nuclear (RAG-1) genes, we were able to distinguish two distinct populations, described here as two new species,Panaspis ericaesp. nov.andP. mundavambosp. nov.Both species are assumed to be endemic to the inselberg. This reinforces our notion of southwestern Angola as a hotspot of skink diversity, and highlights the urgent need for the conservation of Serra da Neve.