Multiple Chromosome Fissions, Including That of the X Chromosome, in Aulacocyclus tricuspis Kaup (Coleoptera, Passalidae) from New Caledonia: Characterization of a Rare but Recurrent Pathway of Chromosome Evolution in Animals.

The male karyotype of Aulacocyclus tricuspis Kaup 1868 (Coleoptera, Scarabaeoidea, Passalidae, Aulacocyclinae) from New Caledonia contains an exceptionally high number of chromosomes, almost all of which are acrocentric (53,X1X2Y). Unlike the karyotypes of other species of the pantropical family Passalidae, which are principally composed of metacentric chromosomes, this karyotype is derived by fissions involving almost all the autosomes after breakage in their centromere region. This presupposes the duplication of the centromeres. More surprising is the X chromosome fragmentation. The rarity of X chromosome fission during evolution may be explained by the deleterious effects of alterations to the mechanisms of gene dosage compensation (resulting from the over-expression of the unique X chromosome in male insects). Herein, we propose that its occurrence and persistence were facilitated by (1) the presence of amplified heterochromatin in the X chromosome of Passalidae ancestor, and (2) the capacity of heterochromatin to modulate the regulation of gene expression. In A. tricuspis, we suggest that the portion containing the X proper genes and either a gene-free heterochromatin fragment or a fragment containing a few genes insulated from the peculiar regulation of the X by surrounding heterochromatin were separated by fission. Finally, we show that similar karyotypes with multiple acrocentric autosomes and unusual sex chromosomes rarely occur in species of Coleoptera belonging to the families Vesperidae, Tenebrionidae, and Chrysomelidae. Unlike classical Robertsonian evolution by centric fusion, this pathway of chromosome evolution involving the centric fission of autosomes has rarely been documented in animals.

Wood fibers are a crucial microhabitat for cellulose- and xylan- degrading bacteria in the hindgut of the wood-feeding beetle Odontotaenius disjunctus.

Introduction: Wood digestion in insects relies on the maintenance of a mosaic of numerous microhabitats, each colonized by distinct microbiomes. Understanding the division of digestive labor between these microhabitats- is central to understanding the physiology and evolution of symbiotic wood digestion. A microhabitat that has emerged to be of direct relevance to the process of lignocellulose digestion is the surface of ingested plant material. Wood particles in the guts of some termites are colonized by a specialized bacterial fiber-digesting microbiome, but whether this represents a widespread strategy among insect lineages that have independently evolved wood-feeding remains an open question. Methods: In this study, we investigated the bacterial communities specifically associated with wood fibers in the gut of the passalid beetle Odontotaenius disjunctus. We developed a Percoll-based centrifugation method to isolate and enrich the wood particles from the anterior hindgut, allowing us to access the wood fibers and their associated microbiome. We then performed assays of enzyme activity and used short-read and long-read amplicon sequencing of the 16S rRNA gene to identify the composition of the fiber-associated microbiome. Results: Our assays demonstrated that the anterior hindgut, which houses a majority of the bacterial load, is an important site for lignocellulose digestion. Wood particles enriched from the anterior hindgut contribute to a large proportion of the total enzyme activity. The sequencing revealed that O. disjunctus, like termites, harbors a distinct fiber-associated microbiome, but notably, its community is enriched in insect-specific groups of Lactococcus and Turicibacter. Discussion: Our study underscores the importance of microhabitats in fostering the complex symbiotic relationships between wood-feeding insects and their microbiomes. The discovery of distinct fiber-digesting symbionts in O. disjunctus, compared to termites, highlights the diverse evolutionary paths insects have taken to adapt to a challenging diet.

Correction of the synonymy of a species of Longior/ Travassos amp; Kloss, 1958 (Nematoda: Oxyuridomorpha: Hystrignathidae) from a Cuban passalid beetle (Coleoptera: Passalidae).

García Coy (1994) described the hystrignathid nematode Longior alius García Coy, 1994 parasitizing the passalid beetle Antillanax pertyi (Kaup, 1869) from Guantánamo province, Eastern Cuba. Morffe García (2011) continued the studies on Cuban Longior and described L. longior Morffe García, 2011. Morffe et al. (2018) redescribed L. longior with the aid of SEM and molecular techniques. In their research the authors studied Longior individuals from the same host species and a locality close to the type locality of L. alius and compared their morphology, measurements and DNA markers with other material of L. longior. As a result of this analysis Morffe et al. (2018) concluded that L. alius and L. longior are conspecific and proposed L. alius as a synonym of L. longior.

Three new species of Longior Travassos Kloss, 1958 (Nematoda: Thelastomatoidea: Hystrignathidae) parasites of passalid beetles (Coleoptera: Passalidae) from Dominican Republic, Mexico and Colombia.

Three new species of the genus Longior Travassos Kloss, 1958 are described and illustrated, namely L. surieli n. sp. in Antillanax dominicanus (Doesburg, 1953) from the Dominican Republic, L. lamothei n. sp. in Passalus punctiger Le Peletier Serville, 1825 from Mexico and Colombia and L. zumpimito n. sp. in P. punctatostriatus Percheron, 1835 from Mexico. These constitute the first records of the genus Longior for the aforementioned countries, rising to nine species in the genus. The new species can be differentiated mainly by the length of their body, oesophagus and tail in both sexes, the extension of the lateral alae in the females and the morphology of the cephalic and posterior end in the males. The molecular phylogeny of the new taxa is inferred by the 28S and 18S rDNA and they form a monophyletic clade with other Longior species. The phylogeny of Longior and that of their passalid hosts reveal coevolutionary relationships. These patterns suggest that the phylogeny of Longior species is probably strongly influenced by the evolutionary trajectories of their passalid hosts.

The megisthanid mites (Mesostigmata: Megisthanidae) of Australia.

The Australian Megisthanidae are revised, resulting in the description of five new species from passalid beetles (Coleoptera: Passalidae) in Queensland: M. manonae sp. nov. from Mastachilus australasicus; M. simoneae sp. nov. from Mastachilus polyphyllus; M. southcotti sp. nov. from Aulacocyclus fracticornis; M. womersleyi sp. nov. from Protomocoelus australis; and M. zachariei sp. nov. from Aulacocyclus kaupii. Megisthanus womersleyi is also based on material from Misima Island, Papua New Guinea, originally identified as Megisthanus doreianus Thorell, 1882. Megisthanus modestus Berlese, 1910, is redescribed based on material from Pharochilus spp. collected from Canberra, New South Wales, Queensland and Tasmania. The Papua New Guinean species Mastachilus papuanus Womersley, 1937 is diagnosed and discussed in relation to the other species from New Guinea. Additional collections of Megisthanus leviathanicus Seeman, 2017 and M. thorelli Womersley, 1937 are also reported. A genus description and a key to the eight Australian species of Megisthanus are provided.

Tonantzin, a New Genus of Bess Beetle (Coleoptera, Passalidae) from a Montane Subtropical Forest in Central Mexico, with a Review of the Taxonomic Significance of the Mesofrontal Structure in Proculini.

Mexico has the third highest diversity of passalid beetles in the World. Here we describe Tonantzin new genus, a new monotypic genus, potentially endemic to the mountains of central Mexico. The new genus is diagnosed by a new configuration of characters from the mesofrontal structure (MFS) in addition to other characters. The MFS in Passalidae has been treated either as a composite complex character or a combination of individual characters. Using a broad taxonomic sample within Proculini, we discuss the taxonomic and systematic implications of the MFS for the tribe. We define the MFS type tepetl. Given the importance of the MFS for passalid taxonomy we propose a new delimitation of the structure using boundaries based on internal and external head structures. We argue that the treatment of the MFS as a complex character better captures the nature of this structure but we ultimately find a need to standardize the way in which this structure is described in the taxonomic literature and used in phylogenetic analyses.

Phylogeny of the genus Yumtaax Boucher (Coleoptera, Passalidae, Proculini): Taxonomic and evolutionary implications with descriptions of three new species.

Yumtaax Boucher (Coleoptera: Passalidae) is an endemic genus from the temperate sierras of Mexico and includes six narrowly distributed species. Yumtaax species have been assigned to several genera of Passalidae throughout history, and a phylogenetic approach is necessary to understand species delimitation and interspecific relationships. This study reconstructed the molecular phylogeny of six Yumtaax morphotypes using parsimony and Bayesian analysis of DNA sequence data from the ribosomal nuclear gene region 28S and the mitochondrial gene regions 12S and cytochrome oxidase I (COI) in addition to morphological characters. Analyses recovered two well-supported Yumtaax clades (the Yumtaax laticornis and Yumtaax imbellis clades) that are possible sister lineages. One synapomorphic morphological character state and the geographic isolation of the group provide corroborative evidence for monophyly. Molecular phylogenetic analyses and traditional morphological examinations also resulted in the discovery of two undescribed Yumtaax species and the discovery of two separate evolutionary lineages (cryptic species) within Yumtaax recticornis. As a result we describe three new species (Yumtaax veracrucensis Beza-Beza, Reyes-Castillo & Jameson, sp. n., Yumtaax cameliae Beza-Beza, Reyes-Castillo & Jameson, sp. n., and Yumtaax jimenezi Beza-Beza, Reyes-Castillo & Jameson, sp. n.), redescribe two species (Yumtaax recticornis [Burmeister 1847] and Yumtaax laticornis [Truqui 1857]), and provide a key to all nine Yumtaax species. This study is one of two studies to use molecular data to evaluate the evolutionary relationships of a genus of Bess Beetles (Passalidae), an ecologically important insect group exhibiting low morphological variability and heretofore lacking molecular phylogenetic study.

Passalid (Insecta: Coleoptera: Passalidae) collected from trunks of Scleronema micranthum (Malvaceae) / Passalídeos (Insecta: Coleoptera: Passalidae) coletados em troncos de Scleronema micranthum (Malvaceae)

Some beetles can attack the wood immediately after the tree is felled, but there are those that start their attack at different stages of wood degradation. Beetles of the family Passalidae belong to this latest category. The objective of this study was to assess the occurrence of beetles of this family in wood samples taken from trunks of Scleronema micranthum, a forest species from Central Amazon. The samples were exposed to biodegradation for 24 months on the forest ground of the Experimental Station of Tropical Silviculture of the National Institute for Amazonian Research, in Manaus, Amazon State, Brazil. During that period, 15 samples were removed from the experiment, every two months, for insect collection and evaluation of infestation. The presence of six species was recorded, all of them of the Passalini tribe: Passalus (Pertinax) latifrons, P. (Passalus) variiphyllus, P. (Pertinax) convexus, P. (Passalus) interstitialis, P. (Passalus) lanei, and Paxillus leachi. Among these species, P. (Passalus) interstitialis was the most abundant, with 18 individuals. This species was the first one to infest the samples and was found between the eighth and twentieth month of the experiment. The infestation occurred predominantly in the bark and sapwood.

Alguns besouros atacam a madeira imediatamente após o abate da árvore, enquanto outros preferem a madeira em diferentes estágios de degradação. Nesta categoria estão inseridos os besouros da família Passalidae. O objetivo deste estudo foi avaliar a ocorrência de besouros dessa família em amostras provenientes de troncos de Scleronema micranthum, espécie florestal da Amazônia Central. As amostras ficaram expostas à biodegradação durante 24 meses no solo da floresta da Estação Experimental de Silvicultura Tropical do Instituto Nacional de Pesquisas da Amazônia, em Manaus, Amazonas, Brasil. Durante esse período, a cada dois meses, 15 amostras foram removidas da floresta para a coleta desses insetos e avaliação da infestação. Foi registrada a presença de seis espécies, todas da tribo Passalini: Passalus (Pertinax) latifrons, P. (Passalus) variiphyllus, P. (Pertinax) convexus, P. (Passalus) interstitialis, P. (Passalus) lanei e Paxillus leachi. Dentre as espécies, P. (Passalus) interstitialis foi a mais abundante, com 18 indivíduos; foi a primeira a infestar as amostras e foi registrada entre o oitavo e o vigésimo mês do experimento. A infestação ocorreu predominantemente na casca e alburno da madeira.

Morfoecología de gremios en escarabajos (Coleoptera: Passalidae) en un gradiente altitudinal en robledales de la Cordillera Oriental, Colombia / Morphoecology guild in beetles (Coleoptera: Passalidae) along an altitudinal gradient in oak forests of the Eastern Cordillera, Colombia

ResumenLos escarabajos pasálidos son componentes importantes de los bosques tropicales debido a que facilitan el reciclaje de nutrientes propios de madera en descomposición, ya sea por acción directa (consumo) o indirecta (facilitando la acción de otros organismos). En la actualidad los estudios ecológicos dentro del grupo son escasos y se han centrado en respuestas a cambios ambientales relacionados con su recurso alimenticio. En el presente estudio se caracterizó la composición gremial de escarabajos pasálidos, distribuida en un gradiente altitudinal, de acuerdo a sus características de aprovechamiento del recurso. Se cuantificaron aspectos morfoecológicos de importancia adaptativa para la explotación diferencial del recurso (medidas corporales, puntos homólogos en cuerpo y alas y series de Fourier en protibias). Se reconocieron cinco especies, 198 grupos familiares y tres gremios: el subcortícola, el alboduramícola y el generalista. La riqueza de la comunidad disminuyó conforme aumentó la altitud. Los cambios entre las variables morfométricas lineales se vieron influenciadas por la altitud; por su parte, los datos morfogeométricos se comportaron independientes del gradiente. El análisis de marcadores morfológicos (morfogeométrico) arrojó información relevante para la delimitación de los gremios ya establecidos en esta familia. Dentro de estos, la forma general del cuerpo junto a las tibias anteriores, aportaron la mayor información de agrupación gremial. La cuantificación de dichos marcadores evidenció la relación entre los tipos de aprovechamiento del recurso, ya que al ser estructuras importantes en el movimiento y consumo de la madera en microzonas particulares, permite plantear roles funcionales puntuales. Reconocer estas variables en interacción con aquellas ecológicas brinda herramientas para el entendimiento de la riqueza y los aportes funcionales de los escarabajos pasálidos al ecosistema.

AbstractBess beetles are important components on tropical forest dead wood nutrient cycling, since they act as direct consumers and ease the consumption by another organism (indirect). Studies of bess beetle ecology are scarce and have focused on communities responses to environmental changes on alimentary resources. We characterized the bess beetles guild composition in an elevation gradient, according to their differential use of resources (microhabitat) and morphological traits quantification (geometric and lineal), as a potential tool to improve our understanding on resource use and functional ecology of beetles. Three guilds (underbark, sapwood-heartwood and generalists feeders), five species and 198 familiar groups were recognized; their richness decreased as elevation increased. Changes in linear morphometric measures were influenced by elevation; morphogeometrical measures were not associated with the elevation gradient, only grouping at guild level were observed. Morphological markers analysis (morphometric) provided information to guild delimitation. Body and metatibiae shape contributed with the best information to guild grouping. Quantification of those structural markers proved the relationship between resource repartition, because they are involved in movement on wood galleries and wood consumption, this fact allowed to propose specific functional roles. The identified patterns have contributed on the understanding of functional processes in Passalidae communities and their role in ecosystem function.

Parthenogenetic reproduction demonstrated in the diploid Spasalus puncticollis (Le Peletier & Serville 1825), n. stat., from the Antilles (Coleoptera, Scarabaeoidea, Passalidae).

Only females were observed in Spasalus crenatus (Mac Leay 1819) in the Antilles, from Puerto Rico to Saint-Vincent, whereas both sexes are in Trinidad and on the continent. No difference in endo- and ectodermic female genitalia could be noticed between the two populations. Chromosomes of specimens from Guadeloupe reveal a 26,XX karyotype, as in females of various sexual species of Passalini, which demonstrates its diploidy. Breedings were developed with isolated immature stages. After nine years, descendants from a single female are demonstrating their parthenogenetic reproduction. This is the first recorded parthenogenesis in Passalidae and a rare telytoky in diploid insects. Relationships between parthenogenesis, diploidy and insularity are discussed in the scheme of geographical parthenogenesis. No discriminant morphological character on adults could be found between the two populations, except the total length. The modes of reproduction distinguishing the two geographically separated populations suggest the presence of two taxa: S. crenatus on the continent and Trinidad; the parthenote S. puncticollis (Le Peletier & Serville 1825), n. stat., on the Arc of the Antilles.

Batwanema gen. n. and Chokwenema gen. n. (Oxyurida, Hystrignathidae), new nematode genera as parasites of Passalidae (Coleoptera) from the Democratic Republic of Congo.

Two new genera and species parasitizing passalid beetles from the Democratic Republic of Congo are described. Batwanema congo gen. n. et sp. n. is characterized by having females with the cervical cuticle armed with scale-like projections, arranged initially in rows of eight elements that gradually divide and form pointed spines toward the end of the spiny region, two cephalic annuli, clavate procorpus and genital tract monodelphic-prodelphic. Two Malagasian species of Artigasia Christie, 1934 were placed in this genus as B. latum (Van Waerebeke, 1973) comb. n. and B. annulatum (Van Waerebeke, 1973) comb. n. Chokwenema lepidophorum gen. n. et sp. n. is characterized by having females with the cervical cuticle armed with scale-like projections, arranged initially in rows of eight elements (similar to Batwanema) that divide gradually, forming spines; a single cephalic annule cone-like, truncated, moderately inflated; procorpus sub-cylindrical and genital tract didelphic-amphidelphic.

Two new genera of nematode (Oxyurida, Hystrignathidae) parasites of Passalidae (Coleoptera) from the Democratic Republic of Congo.

Two new genera and species parasitizing passalid beetles from the Democratic Republic of Congo are described. Kongonema meyeri gen. n. sp. n. is characterized by having females with the cervical cuticle unarmed, first cephalic annule cone-like and truncate, sub-cylindrical procorpus and genital tract didelphic-amphidelphic. The males of Kongonema meyeri gen. n. sp. n. have the procorpus sub-cylindrical, the dorsal cuticle of the tail end thickened, a single large, median mammiform pre-cloacal papilla and a pair of small, pre-cloacal, sub-lateral papillae at a short distance before the level of the cloaca. Lubanema decraemerae gen. n. sp. n. is characterized by the body markedly fusiform, cuticle unarmed and strongly annulated, procorpus sub-cylindrical, isthmus as a constriction between procorpus and basal bulb, genital tract monodelphic-prodelphic and the posterior end rounded with a very short tail appendage.

A new species of Oileus Kaup (Coleoptera, Passalidae) from Guatemala, with a key to the species of the genus.

Oileus gasparilomisp. n. is described from nine specimens from the mountains of Quiché in Guatemala, from cloud forest at 1795 m elevation. This represents the second species of the genus for Guatemala, differing from the closely related Mexican species Oileus rimator (Truqui) in having a straight anterior clypeal border, the postocular sulcus divided by a keel and the pronotum almost straight (not clearly bilobed). A key to the species of Oileus is given.

Coadaptación entre los ácaros (Arachnida: Klinckowstroemiidae) y coleópteros Passalidae (Insecta: Coleoptera) / Co-adaptation between mites (Arachnida: Klinckowstroemiidae) and Passalidae beteles (Insecta: Coleoptera)

Co-adaptation between mites (Arachnida: Klinckowstroemiidae) and Passalidae beteles (Insecta: Coleoptera). Mites of the family Klinckowstroemiidae establish an association with beetles of the family Passalidae known as phoresy. In order to obtain information about this association, we analyzed the relationship between mites of the family Klinckowstroemiidae and beetles of the family Passalidae, as adult mites have been exclusively collected from host beetles. We examined 1 150 beetles collected in seven states of the Mexican Republic, and found 19 species of klinckowstroemiid mites associated with 168 passalids, that belong to 28 different species in 15 genera. Host specificity between species of both groups does not exist, as one species of passalid beetle can have several different symbionts; conversely, a given mite species can associate with passalid beetles of different species and even of different genera. This way, Odontotaenius zodiacus has been found associated with mites of seven species of the genus Klinckowstroemia. Besides, Klinckowstroemia valdezi is associated with five species of passalids. Furthermore, two and even three different species of mites have been found on one host beetle (synhospitality). The lack of congruence between the phylogenies of the mites and that of the beetles indicates that a process of co-adaptation by colonization is going on, because the association is due to the resources that passalid beetles can offer to the mites, like transportation, food and refuge. Since these resources are not host-specific, the klinckowstroemiid mites can climb onto virtually any species of passalid beetles occurring on the same habitat. Rev. Biol. Trop. 60 (2): 599-609. Epub 2012 June 01.

Realizamos un análisis de la relación que existe entre los ácaros Klinckowstroemiidae y los coleópteros Passalidae, puesto que los ácaros adultos se recolectaron exclusivamente sobre pasálidos (huéspedes). Asimismo, examinamos 1 150 coleópteros recolectados en siete estados de la República Mexicana, y encontramos 19 especies de ácaros klinckowstroémidos asociados con 168 de ellos, pertenecientes a 28 diferentes especies de 15 géneros distintos. Estos táxones establecen una relación simbiótica llamada foresia. No existe una especificidad entre las especies de ambos grupos, debido a que una especie de pasálido puede tener varios forontes, y una especie de ácaro puede asociarse a pasálidos de diferentes géneros y especies. Un ejemplo es Odontotaenius zodiacus que presentó a siete especies de Klinckowstroemia asociadas, y por otro lado, Klinckowstroemia valdezi se encuentra asociada a cinco especies de pasálidos. Además, dos o hasta tres especies de ácaros se encontraron sobre un coleóptero huésped (synhospitality). La falta de congruencias entre la filogenia de los ácaros con la de los pasálidos nos indica que se está produciendo un proceso de coadaptación por colonización, y que ésta asociación se debe a los recursos que le brindan los pasálidos a los ácaros: transporte, refugio y alimento. Como estos recursos no son específicos para algún huésped los klinckowstroémidos se suben a cualquier especie de pasálido.

Coynema gen. n., a new genus of nematode (Thelastomatoidea, Hystrignathidae) parasites of Passalidae (Coleoptera) from Cuba.

The new genus Coynemagen. n. is described as parasite of the two passalid beetles from Cuba: Passalus interstitialis Escholtz, 1829 (type host) and Passalus pertyi Kaup, 1869. Females are characterized by the shape of their cephalic end, cervical cuticle unarmed, a sub-cylindrical procorpus with its base abruptly dilated, fore region of intestine dilated as a sac-like structure, genital system didelphic-amphidelphic and eggs markedly ovoid and smooth-shelled. Males have a digestive system similar to females, tail sharply pointed, bearing a Y-like thickening of the dorsal cuticle. They also present a big, median, mammiform pre-cloacal papillae and a pair of small, sub-dorsal pre-cloacal papillae anterior to the cuticular thickening of the tail.

On some Cuban species of the genus Longior Travassos & Kloss, 1958 (Oxyurida, Hystrignathidae), with description of a new species.

Longior zayasi Coy, García & Alvarez, 1993 is established as incertae sedis because the males (declared as the holotype) are inconsistent with the generic diagnosis, particularly in relation to the morphology of the head and tail. Thus, the females of Longior zayasi species (which agree with the generic diagnosis) are renamed and re-described as Longior longior Morffe & García sp. n. We also described males found in the sample and considered as conspecific with the new species. A comparative table with the measurements of the most of the records of Longior longior is given. The male of Longior similis Morffe, García & Ventosa, 2009 is described from the type locality of the species and compared with the known males of the genus. A key to the females of the Cuban Longior is given.

Pseudoscorpionida (Arachnida) em galerias de colônias de Passalidae (Coleoptera, Insecta) em troncos caídos em floresta de terra firme da Amazônia, Brasil / Pseudoscorpionida (Arachnida) found in the galleries made by Passalidae (Coleoptera, Insecta) colonies inside fallen wood of the Amazonian terra firme forest, Brazil

Em sete municípios do Amazonas, um de Rondônia e um de Roraima, foram examinadas 71 colônias de 24 espécies de Passalidae (Coleoptera), pertencentes aos gêneros: Passalus Fabricius, 1792 (14 espécies); Paxillus Mac Leay, 1819 (três); Popilius Kaup, 1871 (três); Spasalus Kaup, 1869 (uma); Verres Kaup, 1871 (uma); Veturius Kaup, 1871 (duas). Foram registradas doze espécies de pseudoscorpiões, incluindo nove gêneros e cinco famílias, listadas a seguir: Chernetidae - Americhernes aff. incertus Mahnert, 1979, Cordylochernes scorpioides (Linnaeus 1758), Lustrochenes similis (Balzan 1892), L. aff. reimoseri Beier, 1932, L. intermedius (Balzan 1892), Phymatochernes crassimanus Mahnert 1979; Chthoniidae - Pseudochthonius homodentatus Chamberlin, 1929; Lechytiidae - Lechytia chthoniiformis (Balzan 1887); Tridenchthoniidae - Tridenchthonius mexicanus Chamberlin & Chamberlin 1945; Withiidae - Cacodemonius sp., Dolichowithius (D.) emigrans (Tullgren 1907), D. (D.) mediofasciatus Mahnert, 1979. Dentre as espécies mais freqüentes (T. mexicanus, L. intermedius e L. aff. reimoseri), ocorreram todos os estágios de desenvolvimento. Foram coletadas de uma a três espécies de pseudoscorpiões em cada colônia individual de besouros passalídeos. T. mexicanus foi a única espécie encontrada em todos os municípios, ocorrendo em 45 colônias de dezenove espécies de passalídeos, sendo a maioria dos exemplares encontrado no subcórtex. L. intermedius foi a segunda espécie mais abundante, ocorrendo em colônias de 11 espécies de Passalidae, a maioria também no subcórtex. L. aff reimoseri ocorreu em 13 colônias de Passalidae, sob a casca, alburno e cerne. L. aff. reimoseri foi a única espécie coletada somente no cerne.

Seventy-one colonies from 24 species of Coleoptera, Passalidae, belonging respectively to the genera Passalus Fabricius, 1792 (14 species), Paxillus Mac Leay, 1819 (three species), Popilius Kaup, 1871 (three species), Spasalus Kaup, 1869 (one species), Verres Kaup, 1871 (one species) and Veturius Kaup, 1871 (two species), were examined from seven municipalities of Amazonas, one of Rondônia and one of Roraima states. Twelve species of psedoscorpions were found, belonging to nine genera and five families, as follows: Chernetidae - Americhernes aff. incertus Mahnert 1979, Cordylochernes scorpioides (Lin. 1758), Lustrochenes similis (Balzan 1892), L. aff. reimoseri Beier, 1932, L. intermedius (Balzan 1892), Phymatochernes crassimanus Mahnert 1979; Chthoniidae - Pseudochthonius homodentatus Chamberlin 1929; Lechytiidae - Lechytia chthoniiformis (Balzan 1887); Tridenchthoniidae - Tridenchthonius mexicanus Chamberlin & Chamberlin 1945; Withiidae - Cacodemonius sp, Dolichowithius emigrans (Tullgren 1907), D. mediofasciatus Mahnert, 1979. Among the most common species, all the development stages of T. mexicanus, L. intermedius and L. aff. reimoseri were found. From one to three species of pseudoscorpions were collected in each colony of passalíd beetles. T. mexicanus, the only species found in all municipalities, was caught in 45 colonies of nineteen species of passalids, the majority of them occurring under bark. L. intermedius, the second most abundant species, was caught in colonies of 11 species of passalids, the majority of them also under bark. Lustrochenes aff. reimoseri was caught in colonies of 13 species of Passalidae under bark and in sapwood and heartwood and was the only species caught exclusively in heartwood.

Hystrignathus dearmasi sp. n. (Oxyurida, Hystrignathidae), first record of a nematode parasitizing a Panamanian Passalidae (Insecta, Coleoptera).

Hystrignathus dearmasi sp. n. (Oxyurida: Hystrignathidae) is described from an unidentified passalid beetle (Coleoptera: Passalidae) from Panama. It resembles Hystrignathus cobbi Travassos & Kloss, 1957 from Brazil, by having a similar form of the cephalic end, extension of cervical spines and absence of lateral alae. It differs from the latter species by having the body shorter, the oesophagus and tail comparatively larger, the vulva situated more posterior and the eggs ridged. This species constitutes the first record of a nematode parasitizing a Panamanian passalid.

A new Paxillus MacLeay, 1819 (Coleoptera: Passalidae: Passalinae) from the state of Amazonas, Brazil / Um novo Paxillus MacLeay, 1819 (Coleoptera: Passalidae: Passalinae) do Estado do Amazonas, Brasil

Paxillus is a neotropical genus belonging to the subfamily Passalinae widespread from Mexico to Argentina. Brazil is known to harbor five species belonging to this genus with most of them presenting at head a flattened central tubercle lacking a free apex. However, one of these species, Paxillus macrocerus Reyes-Castillo & Fonseca, differs from that pattern by having a long central tubercle with a completely free apex. The present study describes and illustrates another new species, which has been found in the Brazilian Amazon, showing this same characteristic.

Paxillus é um gênero neotropical pertencente à subfamília Passalinae, distribuído do México até a Argentina. No Brasil são conhecidas cinco espécies desse gênero, a maioria delas apresentando um tubérculo central achatado sem ápice livre. Entretanto, uma dessas espécies, Paxillus macrocerus Reyes-Castillo & Fonseca, apresenta um padrão diferente, tendo em vista que possui um tubérculo central longo com o ápice completamente livre. O presente estudo descreve e ilustra outra espécie nova, a qual foi encontrada na Amazônia brasileira, que apresenta essa mesma característica.