The present paper reconstructs the biogeographic diversification for Nolana L.f. (Solanaceae), a genus of 89 endemic species largely restricted to fog-dependent desert lomas formations of coastal Peru and Chile. Previous efforts have reconstructed a phylogenetic estimate for Nolana using a combination of molecular markers. Herein, we expand on those results to examine hypotheses of biogeographic origins and diversification patterns. Nolana occupies habitats within a continuous coastal desert and forms a terrestrial archipelago of discrete "islands" unique in size, topography, and species composition. Each locality contains at least one Nolana species and many contain multiple species in sympatry. The genus has a Chilean origin, with the basal clades confined to Chile with wide geographic and ecological distributions. Peru contains two strongly supported clades, suggesting two introductions with subsequent radiation. A Chilean clade of shrubby, small-flowered species appears to have had its origins from the same ancestors of the second line that radiated in Peru and northern Chile. Nolana galapagensis is endemic to the Islas Galápagos, with origins traced to Peruvian taxa with a divergence time of 0.35 mya. Rates of diversification over the past 4.02 mya in Nolana, in one of the driest habitats on Earth, suggest rapid adaptive radiation in several clades. Success in Nolana may be attributed to characters that confer a competitive advantage in unpredictable and water-dependent environments, such as succulent leaf anatomy and ecophysiology, and the reproductive mericarp unique to Nolana. The processes affecting or shaping the biota of western South America are discussed.

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The taxonomy of zooxanthellae in marine invertebrate symbioses is not well understood owing mainly to their lack of reliable morphological di¡erences. Nevertheless, previous work using protein and DNA electrophoreses has set the stage for advancing our taxonomic understanding of cnidarian zooxanthellae. Here we present the use of allozymes as genetic markers for distinguishing algal isolates from tridacnid hosts. Zooxanthellae from seven Tridacna and Hippopus species were isolated and maintained in axenic clonal cultures over many generations. Of 16 enzyme systems, a-and b-esterase (EST), esterase-F (EST-F), glucose phosphate isomerase (GPI), and malate dehydrogenase (MDH) were found suitable polymorphic markers of genetic di¡erences among clonal cultures. Of 39 clonal isolates, 97% were found to be genetically distinguishable. This high extent of genetic variation in zooxanthellae within and between clam species was unexpected, and is di¤cult to explain based solely on the general notion of asexual reproduction in symbiotic zooxanthellae. Our results are also consistent with the occurrence of sexual reproduction in clam zooxanthellae. The close genetic similarity of the symbionts of Tridacna gigas, the largest and fastest-growing clam species, and the di¤culty of initiating their clonal cultures in the given nutrient medium, compared with the symbionts of other clam species, are further indicative of possibly distinct algal symbionts in T. gigas. These ¢ndings are discussed in light of current taxonomic understanding of these organisms.

We present the catalogue of the Cactaceae family of the department of Arequipa, Peru; for which we made field trips between years 2010 and 2016, from 0 to above 4500 m of elevation, we obtained data from national and foreign herbaria, reviewed specialized literature, observed images of the types (HSP, F, B, K, ZZS, HEID, US and U) and consulted specialists. It consists of 56 non-cultivated taxa, grouped into 2 subfamilies (Opuntioideae and Cactoideae), 7 tribes and 20 genera. The most representative taxa correspond to Cumulopuntia (11 spp.), Corryocactus (7 spp.) and Loxanthocereus (6 spp.); 21 of these taxa are endemic and the most diverse of them are Cumulopuntia with 6 spp., Loxanthocereus with 3 spp. and Corryocactus with 3 spp. The taxa are listed in alphabetical order and for each taxon is indicated the scientific name, synonyms and basionyms, bibliographic references, habit, ecology, altitudinal distribution, specimen voucher, departmental distribution, provincial distribution and conservation status. In addition, a dichotomous key is presented for the genera of Arequipa and the taxonomy and distribution are discussed.