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Species of the subtribe Oedionychina not only have a highly uniform diploid number of 2n = 22 (20+X+y) but have the karyotypic peculiarity of possessing extremely large sex chromosomes. We analyzed Paranaita opima embryos and gonadal cells to determine their diploid number, chromosomal morphology, type of sex determination system, constitutive heterochromatin pattern and which chromosomes bear nucleolus organizer regions (NORs). The diploid number of P. opima was 2n = 22 (20+XY/XX) with all chromosomes being metacentric. Chromosome pair 6 showed an interstitial secondary constriction on the short arm. The C-banding technique revealed centromeric constitutive heterochromatin in all chromosomes, which, in pair 6, extended up to the secondary constriction of the short arm, additional C-bands also being present on the Y chromosome. Silver nitrate nucleolar organizer region (Ag-NOR) staining showed NORs on the secondary constriction of pair 6. Fluorochrome analysis with chromomycin A 3 (CMA 3 ), 4'-6-diamidino-2-phenylindole (DAPI) and the distamycin A (DA) counterstain showed that the short arm of chromosome pair 6 exhibited a GC-rich block extending from the proximal to the median region, including part of the secondary constriction. The same techniques also showed AT-rich blocks at the centromeric region of all chromosomes and at the terminal region of the short arm of pair 6. The basic karyotype characteristics and C band pattern of P. opima are similar to those described for other species in the subtribe Oedionychina. The pattern of autosomal NORs observed in P. opima corresponds to that registered in the majority of the Chrysomelidae species.

Cytogenetic analysis of Astylus antis using mitotic and meiotic cells was performed to characterize the haploid and diploid numbers, sex determination system, chromosome morphology, constitutive heterochromatin distribution pattern and chromosomes carrying nucleolus organizer regions (NORs). Analysis of spermatogonial metaphase cells revealed the diploid number 2n = 18, with mostly metacentric chromosomes. Metaphase I cells exhibited 2n = 8II+Xyp and a parachute configuration of the sex chromosomes. Spermatogonial metaphase cells submitted to C-banding showed the presence of small dots of constitutive heterochromatin in the centromeric regions of nearly all the autosomes and on the short arm of the X chromosome (Xp), as well as an additional band on one of the arms of pair 1. Mitotic cells submitted to double staining with base-specific fluorochromes (DAPI-CMA3 ) revealed no regions rich in A+T or G+C sequences. Analysis of spermatogonial mitotic cells after sequential Giemsa/AgNO 3 staining did not reveal any specific mark on the chromosomes. Meiotic metaphase I cells stained with silver nitrate revealed a strong impregnation associated to the sex chromosomes, and in situ hybridization with an 18S rDNA probe showed ribosomal cistrons in an autosomal bivalent.

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A new species of Lobobrachus Sharp, 1885, Lobobrachus cleidecostae sp. nov., from Piauí state, Brazil, is described and illustrated. The genus and Lobobrachus lacerdae Sharp, 1885, are redescribed and the identity of L. alternans Tschitschérine, 1901, is discussed. Based on study of all available specimens and published descriptions it appears that L. alternans cannot be diagnosed and is a synonym of L. lacerdae. However, the syntypes of L. alternans cannot be located, thereby making a final decision on synonymy impossible to substantiate fully. Photographs of the aedeagi of L. lacerdae, L. cleidecostae, and specimens that best correspond to L. alternans, including those putatively identified by Tschitschérine, are presented for the first time.

The Museu de Zoologia da Universidade de São Paulo (MZUSP) houses an important Megalopodidae collection representing 144 species, especially from Brazil and the Neotropical fauna. The type specimens of some species have never been accessed since their original descriptions, and are thus unknown to a major part of the Megalopodidae researchers. Presented here is an illustrated catalogue of the megalopodid type specimens of 32 species deposited at MZUSP, featuring photos of habitus and labels, and complete label data of all the specimens, which originally belonged to Jacintho Guérin’s personal collection. Conflicting and inconsistent data provided in the literature and in the specimens’ labels are addressed. Taxa originally proposed as species varieties are here reaffirmed as valid, with subspecific rank. Agathomerus varians Monrós, 1945 and Plesioagathomerus vittatus Monrós, 1945, originally described as junior synonyms, are considered unavailable names. The subspecific epithet ngriapex is emended into Agathomerus bifasciatus nigrapex Guérin, 1949. An overview of the MZUSP Megalopodidae collection is presented with a history of the arrival of Guérin’s specimens.

A list of 228 types of 79 species of erotylids (Insecta, Coleoptera, Erotylidae -including the Languriinae) of the collection of the Museu de Zoologia da Universidade de São Paulo and the data on their labels are presented.