RESUMO
The rapid squirt of a proteinaceous slime jet endows velvet worms (Onychophora) with a unique mechanism for defence from predators and for capturing prey by entangling them in a disordered web that immobilizes their target. However, to date, neither qualitative nor quantitative descriptions have been provided for this unique adaptation. Here we investigate the fast oscillatory motion of the oral papillae and the exiting liquid jet that oscillates with frequencies f~30-60 Hz. Using anatomical images, high-speed videography, theoretical analysis and a physical simulacrum, we show that this fast oscillatory motion is the result of an elastohydrodynamic instability driven by the interplay between the elasticity of oral papillae and the fast unsteady flow during squirting. Our results demonstrate how passive strategies can be cleverly harnessed by organisms, while suggesting future oscillating microfluidic devices, as well as novel ways for micro and nanofibre production using bioinspired strategies.
RESUMO
Onychophora have undergone a new wave of taxonomic revisions in the last three years. After a recent revision, only two species of Macroperipatus are registered from Brazil: Macroperipatus ohausi and Macroperipatus geayi. The former was only the second species of Onychophora to be described from Brazil, and is herein redescribed, illustrated, and its taxonomic status revised. Macroperipatus ohausi had only been collected at the type locality, Petrópolis, state of Rio de Janeiro, but has not been found there since its discovery. In 2009 we collected two specimens of this species in an Atlantic rain forest fragment in Nova Iguaçu in RPPN dos Petroleiros (also state of Rio de Jane iro). The color of the new specimens was interpreted and described based on the NBS/ISCC System of Color Designation, and corresponds only weakly to that described in earlier publications on M. ohausi. The identification of M. ohausi was based solely on its morphology and compared with its original description. In addition, a female syntype of M. ohausi deposited in the Zoologisches Museum (Hamburg) was examined. We reinvestigated its external morphology and concluded that the dorsal papillae have been misinterpreted in M. ohausi in previous studies of its integument. The new specimens examined are conspecific with M. ohausi mainly by having conical primary papillae, different sized accessory papillae, and by the number of legs. Our material resembles the original description of M. ohausi, for example, in spinous pad and nephridial tubercles, even though these features are not represented in the original description and rede- scription of M. ohausi; these features are further detailed here. We concluded that the dorsal papillae morphology of M. ohausi, shares diagnostic characters, for example, with representatives of the genera Peripatus and Epiperipatus. The dorsal papillae are rounded and not square as in the original description and redescription. Another argument that supports our conclusion is that the RPPN dos Petroleiros, the locality where the new samples were collected, belongs to the same mountain chain and Atlantic mosaic as the original material of M. ohausi. Furthermore, a male of M. ohausi is described here for the first time. Based on our morphological data, we transfered this species to the genus Epiperipatus, proposing a new combination, E. ohausi.
Onychophora experimentó una nueva serie de revisiones taxonómicas en los últimos tres años. Después de una reciente revisión, sólo dos especies de Macroperipatus fueron registradas para Brasil: Macroperipatus ohausi y Macroperipatus geayi. La primera fue solo la segunda especie de Onychophora en ser descrita en Brasil y aquí es redescrita, ilustrada, y su estatus taxonómico revisado. Macroperipatus ohausi sólo se había recolectado en la localidad tipo, Petropolis, Estado de Rio de Janeiro, pero no se ha encontrado allí desde su descubrimiento. En 2009, recolectamos dos ejemplares de esta especie en un fragmento de la ‘Mata Atlantica’ en Nova Iguaçu en el RPPN de los Petroleiros (también en el estado de Rio de Janeiro). El color de los ejemplares nuevos fue interpretado y descrito, basado en el sistema NBS System/ISCC de designación de colores, y correspondió débilmente al descrito en publicaciones anteriores sobre M. ohausi. La identificación de M. ohausi se basó únicamente en su morfología, en comparación con la descripción original. Además, se examinó un sintipo hembra de M. ohausi depositado en Zoologisches Museum (Hamburgo). Nosotros reinvestigamos su morfología externa y concluimos que las papilas dorsales fueron mal interpretadas en M. ohausi en los estudios previos de su integumento. Los nuevos especímenes examinados son coespecíficos con M. ohausi principalmente por tener las papilas primarias cónicas, diferente tamaño de las papilas accesorias, y por el número de patas. Nuestro material se asemeja a la descripción original de M. ohausi, por ejemplo, la almohadilla espinosa y tubérculos nefridiales, aunque estas características no están representadas en la descripción original y redescripcion de M. ohausi, estas características también se detallan aquí. Llegamos a la conclusión de que la morfología de las papilas dorsales de M. ohausi, comparte caracteres de diagnóstico, por ejemplo, con los representantes de los géneros Peripatus y Epiperipatus. Las papilas dorsales son redondeadas y no cuadradas como en la descripción original y redescripción. Otro argumento que apoya nuestra conclusión es que la RPPN dos Petroleiros, la ubicación en la que se recogieron las nuevas muestras, pertenece a la misma cadena de montañas y al mosaico Atlántico, tal como el material original de M. ohausi. Por otra parte, se describe aquí por primera vez un macho de M. ohausi. Basado en nuestros datos morfológicos, transferimos esta especie al género Epiperipatus, que propone una nueva combinación, E. ohausi.
Assuntos
Animais , Feminino , Masculino , Invertebrados/anatomia & histologia , Invertebrados/classificaçãoRESUMO
A revision of the currently known distribution of Onychophora (velvet worms) in Brazil is presented. Twenty-four morphospecies (half of them undescribed) belonging to four genera of the Peripatidae (Peripatus Guilding, 1826, Epiperipatus Clark, 1913, Macroperipatus Clark, 1913 and Oroperipatus Cockerell, 1908) are recorded. This high number of "unidentified" morphospecies is due to three major reasons: the poor quality of the characters used in species-level identification, the inadequate specimen conservation in ethanol, and, in most cases, the lack of additional specimens for analysis of intra- and inter-specific variation. The morphological characters currently used to separate Peripatidae species present a large degree of variation and may not be sufficient to allow accurate identification. There are records of these animals from 16 states, located in four political regions of the country (North, Center-West, Northeast and Southeast). Oroperipatus balzani is recorded for the first time from Brazil. The southernmost record for Onychophora is Itacuruçá island, Mangaratiba, Rio de Janeiro State (E. edwardsii) and the northernmost is Vila Tepequém, Amajari, Roraima State (Epiperipatus sp. 4). Considering the large territorial area of Brazil and the paucity of localities where Onychophora have been collected, we may expect a total diversity of these animals much larger than the currently known one.
RESUMO
A revision of the currently known distribution of Onychophora (velvet worms) in Brazil is presented. Twenty-four morphospecies (half of them undescribed) belonging to four genera of the Peripatidae (Peripatus Guilding, 1826, Epiperipatus Clark, 1913, Macroperipatus Clark, 1913 and Oroperipatus Cockerell, 1908) are recorded. This high number of "unidentified" morphospecies is due to three major reasons: the poor quality of the characters used in species-level identification, the inadequate specimen conservation in ethanol, and, in most cases, the lack of additional specimens for analysis of intra- and inter-specific variation. The morphological characters currently used to separate Peripatidae species present a large degree of variation and may not be sufficient to allow accurate identification. There are records of these animals from 16 states, located in four political regions of the country (North, Center-West, Northeast and Southeast). Oroperipatus balzani is recorded for the first time from Brazil. The southernmost record for Onychophora is Itacuruçá island, Mangaratiba, Rio de Janeiro State (E. edwardsii) and the northernmost is Vila Tepequém, Amajari, Roraima State (Epiperipatus sp. 4). Considering the large territorial area of Brazil and the paucity of localities where Onychophora have been collected, we may expect a total diversity of these animals much larger than the currently known one.
RESUMO
A revision of the currently known distribution of Onychophora (velvet worms) in Brazil is presented. Twenty-four morphospecies (half of them undescribed) belonging to four genera of the Peripatidae (Peripatus Guilding, 1826, Epiperipatus Clark, 1913, Macroperipatus Clark, 1913 and Oroperipatus Cockerell, 1908) are recorded. This high number of "unidentified" morphospecies is due to three major reasons: the poor quality of the characters used in species-level identification, the inadequate specimen conservation in ethanol, and, in most cases, the lack of additional specimens for analysis of intra- and inter-specific variation. The morphological characters currently used to separate Peripatidae species present a large degree of variation and may not be sufficient to allow accurate identification. There are records of these animals from 16 states, located in four political regions of the country (North, Center-West, Northeast and Southeast). Oroperipatus balzani is recorded for the first time from Brazil. The southernmost record for Onychophora is Itacuruçá island, Mangaratiba, Rio de Janeiro State (E. edwardsii) and the northernmost is Vila Tepequém, Amajari, Roraima State (Epiperipatus sp. 4). Considering the large territorial area of Brazil and the paucity of localities where Onychophora have been collected, we may expect a total diversity of these animals much larger than the currently known one.
RESUMO
A revision of the currently known distribution of Onychophora (velvet worms) in Brazil is presented. Twenty-four morphospecies (half of them undescribed) belonging to four genera of the Peripatidae (Peripatus Guilding, 1826, Epiperipatus Clark, 1913, Macroperipatus Clark, 1913 and Oroperipatus Cockerell, 1908) are recorded. This high number of "unidentified" morphospecies is due to three major reasons: the poor quality of the characters used in species-level identification, the inadequate specimen conservation in ethanol, and, in most cases, the lack of additional specimens for analysis of intra- and inter-specific variation. The morphological characters currently used to separate Peripatidae species present a large degree of variation and may not be sufficient to allow accurate identification. There are records of these animals from 16 states, located in four political regions of the country (North, Center-West, Northeast and Southeast). Oroperipatus balzani is recorded for the first time from Brazil. The southernmost record for Onychophora is Itacuruçá island, Mangaratiba, Rio de Janeiro State (E. edwardsii) and the northernmost is Vila Tepequém, Amajari, Roraima State (Epiperipatus sp. 4). Considering the large territorial area of Brazil and the paucity of localities where Onychophora have been collected, we may expect a total diversity of these animals much larger than the currently known one.
RESUMO
A revision of the currently known distribution of Onychophora (velvet worms) in Brazil is presented. Twenty-four morphospecies (half of them undescribed) belonging to four genera of the Peripatidae (Peripatus Guilding, 1826, Epiperipatus Clark, 1913, Macroperipatus Clark, 1913 and Oroperipatus Cockerell, 1908) are recorded. This high number of "unidentified" morphospecies is due to three major reasons: the poor quality of the characters used in species-level identification, the inadequate specimen conservation in ethanol, and, in most cases, the lack of additional specimens for analysis of intra- and inter-specific variation. The morphological characters currently used to separate Peripatidae species present a large degree of variation and may not be sufficient to allow accurate identification. There are records of these animals from 16 states, located in four political regions of the country (North, Center-West, Northeast and Southeast). Oroperipatus balzani is recorded for the first time from Brazil. The southernmost record for Onychophora is Itacuruçá island, Mangaratiba, Rio de Janeiro State (E. edwardsii) and the northernmost is Vila Tepequém, Amajari, Roraima State (Epiperipatus sp. 4). Considering the large territorial area of Brazil and the paucity of localities where Onychophora have been collected, we may expect a total diversity of these animals much larger than the currently known one.