Many orb-weaving spiders exhibit remarkable sexual dimorphism, hampering the matching of males and females in taxonomic studies. This is the case for the spiny Micrathena spiders, a species-rich Neotropical genus with 27% of its species known from a single sex. In this paper we document several undescribed Micrathena specimens, and test whether they belong to some of those incompletely known species. In order to do so, we: (1) tested the phylogenetic position of males and their putative females using a previous morphological dataset; (2) calculated genetic distances among individuals based on a fragment of the mitochondrial gene cytochrome c oxidase subunit I; and (3) examined their geographical distributions. These approaches, isolated or in combination, allowed us to identify and describe the previously unknown males of M. embira Levi, M. reimoseri Mello-Leitão, M. exlinae Levi, M. miles Simon, M. spinulata F.O. Pickard-Cambridge, M. yanomami Magalhães & Santos and M. cornuta (Taczanowski), and the female of M. beta di Caporiacco. We found that the males previously associated with M. bicolor (Keyserling), M. cornuta and M. lata Chickering had been incorrectly matched with females. The latter actually belongs to a hitherto unnamed species, herein described as Micrathena perfida, sp. nov. New geographical data are given for these and other Micrathena species. Our study highlights the importance of using different sources of data for matching the sexes in diverse groups with strong sexual dimorphism. http://zoobank.org/urn:lsid:zoobank.org:urn:lsid:zoobank.org:pub:AFEDA522-D0B4-4902-A747-9721DEED8B89

Abstract:The Brazilian spider fauna comprises thousands of described species, mostly known by only one or two records, and there are large sampling gaps. The spider fauna of the state of Roraima is enigmatic in Brazil and remains largely unknown. Herein, we present a list of spider species recently collected during an expedition in Roraima. Species-level identifications were possible for 229 adult individuals of 54 species. Five species are newly recorded from Brazil, and 30 species are presented for the first time from Roraima. Most of these new records are represented by widespread species, representing the huge and historical deficiency in the spider sampling throughout Roraima.

Recent work in natural language processing (NLP) has yielded appealing results from scaling model parameters and training data; however, using only scale to improve performance means that resource consumption also grows. Such resources include data, time, storage, or energy, all of which are naturally limited and unevenly distributed. This motivates research into efficient methods that require fewer resources to achieve similar results. This survey synthesizes and relates current methods and findings in efficient NLP. We aim to provide both guidance for conducting NLP under limited resources, and point towards promising research directions for developing more efficient methods.

The spider genus Mecynogea comprises nine species distributed predominantly in the Neotropics. Although the genus has been revised recently, several aspects of its taxonomy and morphology are still unresolved. In this paper, Mecynogea infelix (Soares & Camargo, 1948) is removed from the synonymy of Mecynogea bigibba Simon, 1903 and redescribed. Mecynogea chavona Levi, 1997 is considered a junior synonym of M. infelix. The male of Mecynogea buique Levi, 1997 is described and illustrated for the first time. The internal female genitalia of M. buique and M. infelix is described and shown to be remarkably different from each other. We show that part of the intraspecific variation reported previously for the female of M. infelix is the result of epigynum mutilation, possibly during copulation. We also report the presence of an internal branch on the terminal apophysis in the male palp of Mecynogea species. This structure, in some species visible only on the expanded bulb, is shown to be present in all Cyrtophorinae. The internal branch of the terminal apophysis, together with the conductor fully fused to the tegulum, is herein proposed as synapomorphic for the subfamily. Mecynogea lemniscata (Walckenaer, 1841) is recorded for the first time in Bolivia. We also provide new Brazilian records for M. infelix, M. bigibba, M. buique, M. eryhtromela (Holmberg, 1876), and M. sucre Levi, 1997. Mecynogea carvalhoi Mello-Leitão, 1944, currently considered a nomen dubium, is revalidated, transferred to Argiope Audouin, 1826, redescribed and illustrated for the first time.