ABSTRACT The effect of six cryoprotective solutions based on MgCl and methanol, in addtion with sucrose and 10% Aloe vera gel or 10% egg yolk, on the sperm viability in spermatophore and sperm mass of Litopenaeus vannamei was evaluated. Besides, cooling rates of -0.5, -1 and -2 °C/min were used until temperature reached -35, -80 and -100 °C prior to immersion in liquid nitrogen. The sperm viability rate was determined by eosinnigrosin staining. The results showed that the solutions based on MgCl , sucrose plus egg yolk or Aloe vera gel better preserved sperm viability in spermatophore (82.8 ± 2.3% and 72.6 ± 3.1%) and in sperm mass (83.4 ± 2.5% and 76 ± 1.1%) without significant differences with the control group (p>0.05). The freezing curve that presented less damage in spermatophore started from 25 °C and reached -35 °C with a rate of -1 °C/min using a cryoprotective solution with egg yolk and MgCl , showing a sperm viability greater than 80% without significant differences with the control group (p>0.05), and a rate of -2 °C/min in the same temperature range for the group with sperm mass and a solution based on Aloe vera gel. In conclusion, the use of a solution based of MgCl2, sucrose, Aloe vera gel or egg yolk and at a cooling rate of -1 °C/min or -2 °C/min until reaching -35 °C allows a successful freezing of spermatophores or sperm of Litopenaeus vannamei.

RESUMEN Se evaluó el efecto de seis soluciones crioprotectoras basadas en MgCl y metanol, acompañado de sucrosa y gel de Aloe vera al 10% o yema de huevo al 10%, sobre la viabilidad espermática en espermatóforo y masa espermática de Litopenaeus vannamei. Además, se usaron tasas de enfriamiento de -0.5, -1 y -2°C/min hasta lograr descensos de temperatura a -35, -80 y -100 °C previo a la inmersión en nitrógeno líquido. La tasa de viabilidad espermática fue determinada mediante la tinción eosina-nigrosina. Los resultados mostraron que las soluciones basadas en MgCl , sucrosa más yema de huevo o gel de Aloe vera preservaron mejor la viabilidad espermática en espermatóforo (82.8 ± 2.3% y 72.6 ± 3.1%) y en masa espermática (83.4 ± 2.5% y 76 ± 1.1%), sin diferencias significativas con el grupo control (p>0.05). La curva de congelamiento que mostró menor daño en espermatóforo inició desde 25 °C y llegó a -35 °C con una tasa de -1 °C/min empleando una solución crioprotectora con yema de huevo y MgCl , mostrando una viabilidad espermática mayor a 80% sin diferencias significativas con el grupo control (p>0.05), y una tasa de -2 °C/min en el mismo rango de temperaturas para el grupo con masa espermática y una solución basada en gel de Aloe vera. En conclusión, el uso de una solución compuesta por MgCl , sucrosa, gel de Aloe vera o yema de huevo y una tasa de enfriamiento de -1°C/min o -2°C/min hasta alcanzar -35°C permite una protección exitosa en el congelamiento de espermatóforos o masa espermática de Litopenaeus vannamei.

Anolis is one of the largest genus of lizards with more than 380 species distributed in Central and South America, which often difficult their identification. Particularly Anolis meridionalis was described upon one specimen from Paraguay. This species is widely distributed in Brazil, Paraguay and Bolivia. Nevertheless, because the original description is poor in diagnostic characters and the holotype is currently lost, sometimes is difficult to know the identity of specimens of related species. For that reason in this work is designed and described a neotype for Anolis meridionalis with the hope that this helps to solve some taxonomic problems in the southernmost species of the genus.

Anolis es uno de los géneros de lagartijas más grandes con más de 380 especies presentes en el Centro y Sur de América, lo cual dificulta muchas veces su identificación. Particularmente Anolis meridionalis fue descrito en base a un ejemplar procedente de Paraguay. Esta especie se encuentra ampliamente distribuida en Brasil, Paraguay y Bolivia. Sin embargo, debido a que la descripción original es pobre en caracteres diagnósticos y a que el holotipo se encuentra perdido, es difícil en ocasiones conocer la identidad de ejemplares de especies afines. Es por eso que en este trabajo se designa y describe un neotipo para Anolis meridionalis con la esperanza de que ayude a resolver los problemas taxonómicos de las especies más australes del género.

We present an arrangement of the herpetofauna from Paraguay according to the categories of threat proposed by the International Union for Conservation of Nature (IUCN). The 10.9% of the 82 species of amphibians and 14.9% of the 161 species of reptiles analyzed here were in some category of threat of extinction. This means that both short and long term conservation actions are needed to avoid loss of species.

Se presentan los resultados de la categorización de la herpetofauna de la República del Paraguay, utilizando las categorías propuestas por la Unión Internacional para la Conservación de la Naturaleza (UICN). El 10,9% de las 82 especies de anfibios analizados y el 14,9% de las 161 especies de reptiles, se encuentra en alguna de las categorías de riesgo de extinción propuestas por UICN. Esto indica que es necesario encarar acciones de conservación a corto y largo plazo para evitar y/o disminuir la pérdida de espécies.

As serpentes dos gêneros pseudoboinos Boiruna e Clelia, este último provavelmente não monofilético, estão distribuídas desde o sul da Argentina, Brasil e Uruguai até o centro do México. Seis de seus membros ocorrem no Paraguai e na Argentina: B. maculata, Clelia bicolor, C. clelia, C. plumbea, C. quimi, e C. rustica. Historicamente, existiram confusões entre as espécies de maior tamanho (B. maculata, C. clelia, C. plumbea e C. rustica) e entre as espécies pequenas (C. bicolor e C. quimi). Todas as espécies, exceto C. rustica, possuem mudanças ontogenéticas na sua coloração. As espécies podem ser diferenciadas através do seu tamanho, cor, espinhos do hemipenis, e número de escamas loreais, supralabiais, e ventrais. A maior parte da diferenciação evolutiva em Boiruna e Clelia parecem ter ocorrido na região anterior da cabeça, pelo que mostram as diferentes proporções das escamas da região loreal. Boiruna maculata é a espécie de maior amplitude ecológica; é encontrada na maioria das formações vegetais existentes ao norte do paralelo 38 no centro da Argentina, ausente apenas na região de sedimentos deltaicos da província de Buenos Aires, Argentina, e nos amplos vales e colinas onduladas do leste do Paraguai. Clelia bicolor é mais comum nos vales dos rios Paraguai e Paraná, e com alguns registros na base dos Andes no norte da Argentina. Clelia clelia distribui-se ao longo do Rio Paraguai e do baixo Paraná, e quase todo o leste do Paraguai. Clelia plumbea aparentemente é parapátrida de C. clelia ao longo do rio Paraná no sudeste do Paraguai e na província de Misiones, Argentina. O extremo leste da distribuição de C. quimi limita-se com o extremo oeste da distribuição de C. bicolor na mesma região sem que, aparentemente, haja superposição. Não existe material de referência que prove a presença de Clelia rustica no Paraguai. Na Argentina, ela é uma espécie encontrada em áreas temperadas; ao norte do paralelo 30, é encontrada na base dos Andes e nas florestas úmidas da província de Misiones. Ao sul, está amplamente distribuída além do paralelo 40.

Snakes of the pseudoboine genera Clelia, which is probably polyphyletic, and Boiruna are distributed from southern Argentina, southern Brazil, and Uruguay northwards into central México. Six members occur in Paraguay and Argentina: B. maculata, Clelia bicolor, C. clelia, C. plumbea, C. quimi, and C. rustica. Historically, there has been taxonomic confusion among the larger species (B. maculata, C. clelia, C. plumbea, and C. rustica) and between the small species (C. bicolor and C. quimi). All of the species except C. rustica have distinct ontogenetic color changes. Species can be distinguished on the bases of size, color, hemipenial spines, and loreal, supralabial, and ventral scale counts. Much of the morphological evolutionary differentiation in Boiruna and Clelia seems to have taken place in the snout region, as evidenced by the differing proportions of the scales of the loreal region. Boiruna maculata has the widest ecological amplitude. It is broadly distributed in most vegetation types north of the 38th parallel in central Argentina, being absent only from the deltaic sediments of Buenos Aires Province, Argentina and the broad valleys and rolling hills of eastern Paraguay. Clelia bicolor is most common in the Paraguay and Paraná river valleys, with a few records from the Andean foothills in northern Argentina. Clelia clelia is distributed along the Río Paraguay and the lower Paraná, and is also found throughout much of eastern Paraguay. Clelia plumbea is apparently parapatric with C. clelia along the Río Paraná in southeastern Paraguay and Misiones Province, Argentina. The ranges of C. quimi to the east and C. bicolor in the west about in this same region without apparent overlap. There are no vouchered records of Clelia rustica from Paraguay. In Argentina, it is a species of temperate climates; north of the 30th parallel, it occurs in the Andean foothills and the wet forests of Misiones Province. Southwards, it is widely distributed to beyond the 40th parallel.