No abstract

This work deals with the comparative cytogenetic analysis of four Neotropical Elateridae species and reviews the nucleolar organizer region (NOR) patterns on Coleoptera chromosomes, for the first time. The cytogenetic characterization of Conoderus malleatus (Conoderini), Pyrearinus candelarius, Pyrophorus divergens and Pyrophorus punctatissimus (Pyrophorini) was accomplished through the study of mitotic and meiotic cells submitted to standard (Giemsa) and differential staining [silver impregnation and GC-specific chromomycin A 3 (CMA 3 ) plus AT-specific 4¢-6-diamidino-2-phenylindole (DAPI) fluorochromes]. The analysis of spermatogonial cells revealed the diploid numbers: 2n ¼ 17 in C. malleatus and 2n ¼ 15 in P. candelarius, P. divergens and P. punctatissimus. In these species, the X0 type sex-determination system and the acrocentric morphology of almost all chromosomes were observed. The study of meiotic cells of the four species revealed the occurrence of total synapsis between the autosomes, the presence of one terminal or interstitial chiasma in the majority of the bivalents, and the reductional behaviour and regular segregation of all chromosomes. Although the three Pyrophorini species demonstrated many similar karyotypical characteristics, there was one discrepancy, which was noted in the diplotene cells and concerns the number of bivalents with two chiasmata; P. candelarius only presented one bivalent, P. divergens showed two bivalents and P. punctatissimus exhibited up to four bivalents with two chiasmata. Testicular cells impregnated with silver nitrate demonstrated two terminal NORs located on the fourth autosomal pair of the Conoderini species and on the second autosomal pair of the three Pyrophorini representatives. Use of CMA 3 /distamycin A (DA)/DAPI staining on the P. candelarius and P. punctatissimus chromosomes revealed that the CMA 3 labelled regions were coincident with the NORs. The main strategies of karyotypical differentiation that have occurred among the four Elateridae species and other related species, and the general trends of the NOR shifts during Coleoptera chromosomal evolution are discussed in this work.

Beetles are the most species-rich animal radiation and are among the historically most intensively studied insect groups. consequently, the vast majority of their higher-level taxa had already been described about a century ago. In the 21st century, thus far, only three beetle families have been described de novo based on newly collected material. Here, we report the discovery of a completely new lineage of soft-bodied neotenic beetles from the Brazilian Atlantic rainforest, which is one of the most diverse and also most endangered biomes on the planet. We identified three species in two genera, which differ in morphology of all life stages and exhibit different degrees of neoteny in females. We provide a formal description of this lineage for which we propose the new family Jurasaidae. Molecular phylogeny recovered Jurasaidae within the basal grade in elateroidea, sister to the well-sclerotized rare click beetles, cerophytidae. this placement is supported by several larval characters including the modified mouthparts. The discovery of a new beetle family, which is due to the limited dispersal capability and cryptic lifestyle of its wingless females bound to long-term stable habitats, highlights the importance of the Brazilian Atlantic rainforest as a top priority area for nature conservation.Coleoptera (beetles) is by far the largest insect order by number of described species. Approximately 400,000 species have been described, and many new ones are still frequently being discovered even in regions with historically high collecting activity 1 . Because this group has been intensively studied since the age of early systematists, and most of the major higher-level taxa had already been described by about a century ago, discoveries of new beetle families are nowadays a rare occurrence. The vast majority of recent family descriptions is based on the already known taxa for which a new systematic placement was recovered by the use of phylogenetic analyses 2-5 . Thus, only three beetle families have been erected de novo in the 21st century based on newly collected material. Firstly, Aspidytidae were described based on two species from South Africa and China, which currently represent monotypic genera 6,7 . Secondly, the monotypic family Meruidae was created for a hitherto undescribed lineage from Venezuela 8 . Finally, the new monogeneric family Iberobaeniidae was described based on three species from the southern part of the Iberian Peninsula 9,10 . Whereas both Aspidytidae and Meruidae represent semiaquatic families within the suborder Adephaga, Iberobaeniidae were recovered as a deep branch in the polyphagan superfamily Elateroidea 9 .Elateroidea (the click-beetles, soldier-beetles, fireflies and relatives), the largest superfamily of the series Elateriformia, form one of the major and oldest polyphagan lineages 11,12 . Currently, they contain approximately 25,000 described species classified into 13 families [13][14][15][16] . The elateroid beetles exhibit extraordinary morphological diversity. Some lineages contai...

The speciose Brazilian Elateridae fauna is characterized by high karyotypic diversity, including one species (Chalcolepidius zonatus Eschscholtz, 1829) with the lowest diploid number within any Coleoptera order. Cytogenetic analysis of Conoderus dimidiatus Germar, 1839, C. scalaris (Germar, 1824,) C. ternarius Germar, 1839, and C. stigmosus Germar, 1839 by standard and differential staining was performed with the aim of establishing mechanisms of karyotypic differentiation in these species. Conoderus dimidiatus, C. scalaris, and C. ternarius have diploid numbers of 2n(male) = 17 and 2n(female) = 18, and a X0/XX sex determination system, similar to that encountered in the majority of Conoderini species. The karyotype of C. stigmosus was characterized by a diploid number of 2n = 16 and a neoXY/neoXX sex determination system that was highly differentiated from other species of the genus. Some features of the mitotic and meiotic chromosomes suggest an autosome/ancestral X chromosome fusion as the cause of the neoXY system origin in C. stigmosus. C-banding and silver impregnation techniques showed that the four Conoderus species possess similar chromosomal characteristics to those registered in most Polyphaga species, including pericentromeric C band and autosomal NORs. Triple staining techniques including CMA3/DA/DAPI also provided useful information for differentiating these Conoderus species. These techniques revealed unique GC-rich heterochromatin associated with NORs in C. scalaris and C. stigmosus and CMA3-heteromorphism in C. scalaris and C. ternarius.

Fireflies (Coleoptera: Lampyridae) are soft-bodied beetles usually associated with mesic and hydric habitats. As such, terrestrial firefly larvae are commonly found in marshy environments and stream banks, while aquatic larvae might dwell in ponds, streams, mangroves, and even brackish water. Larval biology is especially important in fireflies, as the majority of species are extremely semelparous – that is, adults rely on resources gathered during larval stages. Despite their crucial relevance in firefly biology, larvae of only near 1% firefly species have been studied, and the majority of species remain known only from adult stages. That is especially true in the Neotropical region, where they are most diverse. Here, we describe Psilocladus costae sp. nov. after the study of adults and immature stages, the latter reported for the first time for the monotypic subfamily Psilocladinae McDermott, 1964. Interestingly, adults were first obtained by rearing the larvae, the former usually fly fairly high (ca. 10 m) and are therefore seldom collected at ground level by conventional methods (e.g., active search, Malaise traps). The new species is found in the Brazilian Atlantic Rainforest, inhabiting canopy bromeliads, an unprecedented habit for fireflies.