Ventral Pad Research Articles

The larvae of Cora inca Selys, 1873 and Polythore gigantea (Selys, 1853) from Colombia (Odonata: Polythoridae), with a larval diagnoses of some genera in the family

The larvae of Cora inca Selys, 1873 and Polythore gigantea (Selys, 1853) were found in first and second order forested streams at the Tatamá Natural National Park in the Colombian Western Andes. Their final larval stadia are here described and figured. Cora inca differs from the larvae of C. cyane Selys, 1853 and C. marina Selys, 1868 by a combination of features including presence of an irregular patch of minute, gray scales to each side of the ventral midline on the ventral pad of hypopharynx, paraprocts with five projections, and the position of epiproct and paraproct projections. On the other hand, the larva of P. gigantea differs from the larva of P. spaeteri Burmeister & Börzsöny, 2003 by antennal scape slightly shorter than 3rd antennomere, prementum 0.10x longer than its widest part, and the position of epiproct and paraproct projections. Although most of the larvae in the family Polythoridae are still unknown, here we discuss the main morphological characteristics that help to diagnose some of the genera in this family, presenting a regional taxonomic key that includes the genera Cora Selys, 1853, Euthore Selys, 1859, Miocora Calvert, 1917, and Polythore Calvert, 1917.

Force-transmitting structures in the digital pads of the tree frog Hyla cinerea: a functional interpretation.

The morphology of the digital pads of tree frogs is adapted towards attachment, allowing these animals to attach to various substrates and to explore their arboreal habitat. Previous descriptions and functional interpretations of the pad morphology mostly focussed on the surface of the ventral epidermis, and little is known about the internal pad morphology and its functional relevance in attachment. In this study, we combine histology and synchrotron micro‐computer‐tomography to obtain a comprehensive 3‐D morphological characterisation of the digital pads (in particular of the internal structures involved in the transmission of attachment forces from the ventral pad surface towards the phalanges) of the tree frog Hyla cinerea. A collagenous septum runs from the distal tip of the distal phalanx to the ventral cutis and compartmentalises the subcutaneous pad volume into a distal lymph space and a proximal space, which contains mucus glands opening via long ducts to the ventral pad surface. A collagen layer connects the ventral basement membrane via interphalangeal ligaments with the middle phalanx. The collagen fibres forming this layer curve around the transverse pad‐axis and form laterally separated ridges below the gland space. The topological optimisation of a shear‐loaded pad model using finite element analysis (FEA) shows that the curved collagen fibres are oriented along the trajectories of the maximum principal stresses, and the optimisation also results in ridge‐formation, suggesting that the collagen layer is adapted towards a high stiffness during shear loading. We also show that the collagen layer is strong, with an estimated tensile strength of 2.0–6.5 N. Together with longitudinally skewed tonofibrils in the superficial epidermis, these features support our hypothesis that the digital pads of tree frogs are primarily adapted towards the generation and transmission of friction rather than adhesion forces. Moreover, we generate (based on a simplified FEA model and predictions from analytical models) the hypothesis that dorsodistal pulling on the collagen septum facilitates proximal peeling of the pad and that the septum is an adaptation towards detachment rather than attachment. Lastly, by using immunohistochemistry, we (re‐)discovered bundles of smooth muscle fibres in the digital pads of tree frogs. We hypothesise that these fibres allow the control of (i) contact stresses at the pad–substrate interface and peeling, (ii) mucus secretion, (iii) shock‐absorbing properties of the pad, and (iv) the macroscopic contact geometry of the ventral pad surface. Further work is needed to conclude on the role of the muscular structures in tree frog attachment. Overall, our study contributes to the functional understanding of tree frog attachment, hence offering novel perspectives on the ecology, phylogeny and evolution of anurans, as well as the design of tree‐frog‐inspired adhesives for technological applications.

Loimia ramzegasp. nov., a new giant species of Terebellidae (Polychaeta) from French waters (Brittany, English Channel)

A new species of Terebellidae,Loimia ramzegasp. nov., has been identified from North Brittany beaches (English Channel). This new species is characterized by its gigantic size (max 650 mm, live), two pairs of lateral lappets on segments 1 and 3; first pair more ventral, second pair more developed and lateral but oblique, with wavy edge. Nine ventral pads from segment 2 (fused on segments 2 and 3), first three pads swollen, next ones subsequently decreasing in size. Three types of notochaetae, asymmetrically bilimbate, symmetrically bilimbate and capillary. Uncini pectinate with 6 teeth (some with 5 teeth) slightly decreasing in size, in one vertical row. Pygidium with about 14 long conical marginal papillae surrounding anus.

Review of genera within theAxionice/Pistacomplex (Polychaeta, Terebellidae), with discussion of the taxonomic definition of other Terebellidae with large lateral lobes

The definitions of terebellid genera have caused considerable confusion. Some genera, such asPistaMalmgren, 1866, are clearly not monophyletic and the need to revise them is widely accepted. A phylogenetic analysis of genus level morphological characters within theAxionice/Pistacomplex and other Terebellidae with large lateral lobes revealed two well defined groups; these differed in the arrangement of different forms of lateral lobes on segments 1–3, the shape of the branchiae, structure of the ventral pads and, if present, the origin of the manubrium on the uncini. One of the groups includes the type species ofPista; the other includes the type species ofAxioniceand almost all the other genera whose taxonomic status is discussed in this paper (Betapista,Eupistella,Lanice,Loimia,Paraxionice) which we propose to treat as its junior synonyms. Three other genera –Lanicides,LanicolaandScionella– did not fall within these two groups; they are accepted as distinct. A complete list of species ofAxioniceandPistais provided; 39 species currently included inPistashould be moved toAxionice, thusAxioniceincludes at least 94 species. Many authors’ descriptions of the type species ofPista(Amphitrite cristataMüller, 1776) conflict with the original description.Amphitrite cristatas. str. has been described as a new species:Scionella lornensisPearson, 1969 and the type species of a new genus:PistellaHartmann-Schröder, 1996.Scionella lornensisis here considered a junior synonym ofAmphitrite cristata. Redescriptions of the type species ofAxioniceandPistaare provided.

Load redistribution in walking and trotting Beagles with induced forelimb lameness

To evaluate the load redistribution mechanisms in walking and trotting dogs with induced forelimb lameness. 7 healthy adult Beagles. Dogs walked and trotted on an instrumented treadmill to determine control values for peak and mean vertical force as well as vertical impulse for all 4 limbs. A small sphere was attached to the ventral pad of the right forelimb paw to induce a reversible lameness, and recordings were repeated for both gaits. Additionally, footfall patterns were assessed to test for changes in temporal gait variables. During walking and trotting, peak and mean vertical force as well as vertical impulse were decreased in the ipsilateral forelimb, increased in the contralateral hind limb, and remained unchanged in the ipsilateral hind limb after lameness was induced. All 3 variables were increased in the contralateral forelimb during trotting, whereas only mean vertical force and vertical impulse were increased during walking. Stance phase duration increased in the contralateral forelimb and hind limb during walking but not during trotting. Analysis of the results suggested that compensatory load redistribution mechanisms in dogs depend on the gait. All 4 limbs should be evaluated in basic research and clinical studies to determine the effects of lameness on the entire body. Further studies are necessary to elucidate specific mechanisms for unloading of the affected limb and to determine the long-term effects of load changes in animals with chronic lameness.

Homology of prostomial and pharyngeal structures in eunicida (Annelida) based on innervation and morphological similarities

Eunicidan bristle worm families are commonly identified by the shape of their prostomia and pharyngeal structures. However, current hypotheses of homology among these structures are conflicting, making it difficult to assess morphological evolution, reconstruct phylogeny, and produce a stable classification. To generate more consistent hypotheses of homology among eunicidan anterior structures, the author examined the anterior morphology and the nervous system stained with anti-alpha-tubulin and serotonin antibodies in representative species of Eunicidae, Onuphidae, Oenonidae, Dorvilleidae and Lumbrineridae. The shape of the brain varied conspicuously among families; however, it has mostly the same commissures (usually two of the dorsal and five of the ventral roots of the circumoesophageal connective). The stomatogastric system is also conservative in composition, having two main pairs of stomatogastric nerves which vary in their relative position among the different families. Innervation similarities combined with correspondence and topological morphological similarities made it possible to present explicit hypotheses of primary homology of features, such as buccal lips, pharyngeal fold, and dorsolateral fold anterior extension. Buccal lips are present in all families; however, ventral pads on the prostomium of the Dorvillea line of Dorvilleidae are anterior prolongations of the pharyngeal fold and not buccal lips. All examined taxa, except dorvilleid species, have conspicuous dorsolateral fold anterior extension. In Eunicidae, this anterior extension is a transverse band, while in other families it is a pair of folds. Observed similarities also gave insights on the homology of maxillary elements of Dorvilleidae, providing background knowledge for future studies.

Descripción de una especie nueva de <i>Meloe</i> Linnaeus, 1758 del subgénero <i>Eurymeloe</i> Reitter, 1911 (Coleoptera, Meloidae) del norte de Marruecos

We describe a new species of Meloe (Coleoptera: Meloidae), subgenus Eurymeloe , included in the M. rugosus species group, related to species of the M. murinus subgroup. The specimens of the new species studied were found along the western Rif mountain chain (Talassemtane National Park) in northwestern Morocco, and were located in hiperhumid montane forest habitats. The new species is characterized by having: a dull black coloration with greyish hue; a very short, curved, and not dense, yellow-whitish pilosity, which does not form tufts; a subrectangular transverse pronotum with a marked median grove and two longitudinal lateral depressions; head and pronotum punctures well impressed and subconfluent; elytra sligtly rugose; tarsomeres with slightly developed ventral pads; aedeagus with curved parameres, laterally depressed, apically pointed, with the distal ventral hook of median lobe close to apex. The new taxon es phenetically similar to M. nanus, M. baudueri and M. flavicomus , but distinguished from all of them by the mentioned morphological external and male genitalia characters. The distribution of the new species, only known from its type locality, overlaps those of M. murinus, M. nanus and possibly M. baudueri , but so far it has not been found in strict sympatry with any of them. The habitat type inhabited by the new species, mountain areas with mixed forests of Pinus pinaster hamiltonii var. maghrebiana, P. nigra mauritanica and Abies maroccana (endemic taxa of the limestone northwestern Rif mountain chain), contrasts with other habitat types recorded for species of the M. (E). murinus species subgroup of the subgenus Eurymeloe .

The median‐fin skeleton of the Eastern Atlantic and Mediterranean clingfishes Lepadogaster lepadogaster (Bonnaterre) and Gouania wildenowi (Risso) (Teleostei: Gobiesocidae)

Previous research on the osteology of the Gobiesocidae focused mostly on the neurocranium and the thoracic sucking disc (formed by the paired-fin girdles). Little attention has been paid to the skeleton of the median fins. The dorsal- and anal-fin skeleton of Lepadogaster lepadogaster and other gobiesocids (excluding Alabes, which lacks these fins) are characterized by the absence of spines, branched fin-rays, and middle radials. In gobiesocids, the distal radials never ossify and consist of elastic hyaline-cell cartilage. Gouania wildenowi is unique among gobiesocids in having further reductions of the dorsal- and anal-fin skeleton, including a notable decrease in the size of the proximal-middle radials in an anterior-posterior direction. Unlike L. lepadogaster, which exhibits a one-to-one relationship between the dorsal- and anal-fin rays and proximal-middle radials, G. wildenowi has a higher number of proximal-middle radials than distal radial cartilages and fin rays in the dorsal and anal fins. In G. wildenowi, the dorsal- and anal-fin rays do not articulate with the distal tip of the proximal-middle radials but are instead positioned between proximal-middle radials, which is unusual for teleosts. Previously unrecognized dorsal and ventral pads of elastic hyaline-cell cartilage are also present in the caudal skeleton of L. lepadogaster, G. wildenowi, and all other gobiesocids examined.

A new species of <i>Pista</i> (Annelida: Polychaeta: Terebellidae) from shallow waters of Shizugawa Bay, Sanriku Coast, Japan

A new species of the genus Pista (Annelida: Polychaeta: Terebellidae) was found on a boulder bottom in shallow waters of of Shizugawa Bay, Sanriku coast, northern Honshu, Japan. Individuals of this species measure 5 to 10 cm long and 3 to 5 mm wide. There are two pairs of branchiae on segments 2 and 3, each with an annulated long stalk and many dichotomous branches. The peristomium and segment 3 have elongate, semi-circular lateral lobes, segments 2 and 4 each have small lobes, segments 5 and 6 have very small lobes inserted between the neuropodium and ventral pad. Individuals of the new species have 17 pairs of notopodia from segment 4 and conical nephridial papillae on segments 6 and 7. The new Japanese species differs from all known species in the structure of the branchiae and the lateral lobes of anterior chaetigers.