Medial Notch Research Articles

A new dinosaur tracksite with small footprints in the Urbión Group (Cameros Basin, Lower Cretaceous, La Rioja, Spain)

A new dinosaur tracksite (La Rueda) with ten small tridactyl footprints (the length ranges between 9 and 15 cm) from the Urbión Group (Cameros Basin, Lower Cretaceous, La Rioja, Spain) is described. The footprints are approximately as long as wide and have high divarication angles between digits II-IV (~80º), some pad impressions on each digit, claw marks, a medial notch and a circular heel pad impression. They are here classified as indeterminate ornithopod footprints and contribute to the increase in the dinosaur ichnodiversity of the Urbión Group. Small dinosaur footprints are scarce in the worldwide fossil record. In the Urbión Group, large dinosaur tracks are much more frequent than small ones. This scarcity could be explained as ecological biases (dearth of small individuals in an area). Nevertheless, the number of small footprints in the Urbión Group is instead the product of by preservation biases (coarse grain sediments and fluvial erosive bases) and the weathering and erosion processes (brittle nature of the rock) that affect especially to small tracks than large ones identified in this Group.

A new species of Bothriocephalus Rudolphi, 1808 (Eucestoda: Bothriocephalidea) from the channel bull blenny Cottoperca gobio (Günther) (Perciformes: Bovichtidae) on the Patagonian shelf off Argentina.

Bothriocephalus timii n. sp. is the first tapeworm species reported from a bovichtid fish. The new species was commonly found (prevalence 85%) in the intestine of Cottoperca gobio (Günther) collected on the Patagonian shelf off Argentina. It is characterised by a strobila with segments and proglottides usually longer than wide, having posterolateral wing-like expansions with a medial notch on both the dorsal and ventral surfaces; a scolex with an apical disk; elongate bothria opening posteriorly, with laterally and longitudinally extended convex lappets; testes 42-185 in number, in one layer, arranged in two lateral continuous bands along the strobila; an elongate cirrus-sac, situated obliquely, with the proximal part curved anteriolaterally; and an ovary which is usually butterfly-shaped. The new species is morphologically similar to B. bengalensis Devi, 1975 from Carangoides plagiotaeniata Bleeker, B. branchiostegi Yamaguti, 1952 from Branchiostegus japonicus Houttuyn, B. carangis Yamaguti, 1968 from C. ferdau Forsskål and B. gadellus Blend & Dronen, 2003 from Gadella imberbis (Vaillant) based on the presence of posterolateral wing-like expansions with a medial notch on dorsal and ventral surfaces of segments and proglottides along the strobila. Bothriocephalus timii n. sp. differs from B. bengalensis, B. branchiostegi and B. carangis in the absence of a vaginal sphincter and from B. gadellus in the number of testes and the size of scolex. Unpublished molecular data suggest that B. timii is most closely related to B. australis Kuchta, Scholz & Justine, 2009 from Platycephalus spp. and B. scorpii (Müller, 1776) from Myoxocephalus scorpius (Linnaeus). The genus Indobothrium Sedova & Gulyaev, 2009 is herein considered a junior synonym of Bothriocephalus Rudolphi, 1808.

Gyrodactylus patersonin. sp. (Monogenea: Gyrodactylidae) Infecting Atlantic Silverside (Menidia menidia) from Nova Scotia, Canada

Gyrodactylus patersoni n. sp. is described from the gills of the Atlantic silverside, Menidia menidia (L.) (Atherinidae), from Kingsport, Nova Scotia, Canada. The new species is the second species of Gyrodactylus to be reported from this host and is characterized by having small hamuli with short hamuli roots, a ventral bar with anterolateral processes of moderate size and a linguiform membrane, a dorsal bar with medial notch, and a male copulatory organ with 1 large spine and 5–6 terminal spines arranged in a single arched row. Gyrodactylus patersoni n. sp. most closely resembles Gyrodactylus stephanus Mueller, 1937 described from the mummichog, Fundulus heteroclitus L., from the northeastern coast of North America. The 2 species can be differentiated by the size of the hamuli (32.5 µm vs. 40.0 µm), length of the anterolateral processes (4.5 µm vs. 8.5 µm), number of copulatory spines (5–6 vs. 6–8) and, to a lesser degree, the shape of the marginal hook in that members of Gyrodactylus patersoni n. sp. have a slightly reduced heel and a more upright shaft. The description includes 438 sequenced base pairs (bp) of the 18S gene (including the V4 region) as well as 936 bp of the ITS region (ITS-1/5.8S/ITS-2). Basic Local Alignment Search Tool (BLAST) queries for the ITS and 18S fragments returned G. stephanus as most genetically similar (97.6% and 99.1%, respectively). Gyrodactylus patersoni n. sp. is a member of the Gyrodactylus arcuatus-group, a lineage that has successfully radiated through phylogenetically diverse fishes of the northern hemisphere, most of which share a littoral marine habitat.

Six new deep-water sternaspid species (Annelida, Sternaspidae) from the Pacific Ocean

Most sternaspid species have been described from shallow water, and Caulleryaspis Sendall & Salazar-Vallejo, 2013 includes one deep water species: C. gudmundssoni Sendall & Salazar-Vallejo, 2013 from Iceland. In Sternaspis Otto, 1821, the most speciose genus, most species were described from shallow water and only three thrive in deep water: S. maior Chamberlin, 1919 from the Gulf of California, S. princeps Selenka, 1885 from New Zealand, and S. riestchi Caullery, 1944 from Indonesia. The study of some deep sea sternaspids from the Pacific Ocean in the collections of six research institutions resulted in the discovery of six undescribed species, and for three of them there were abundant materials showing ventro-caudal shield development. Caulleryaspis fauchaldi sp. n. is described based on specimens from Oregon and California; it differs from the known species because it has a shield with rounded anterior margins and its peg chaetae form thin, small spines. Caulleryaspis nuda sp. n. was collected off Oregon; it is unique because its shield lacks a layer of sediment particles firmly attached, but has instead a thin layer of small particles loosely attached. Four other species are newly described in Sternaspis: S. annenkovae sp. n. was collected east off the northern Kurile Islands in about 4,000 m depth; it differs from other species by having a bicolored body, with the introvert darker than the abdomen, and its ventro-caudal shield plates are divergent resulting in a divided fan. The second species, S. maureri sp. n. was found off Peru in 1296–6489 m water depths and in the Southwestern Pacific in 795–3830 m; it resembles S. williamsae sp. n. but differs because its shield has better-developed ribs, the fan has a shallow or indistinct median notch and has lateral notches well-developed. The third species, S. uschakovi sp. n., was found in the Okhotsk Sea in 592–1366 m, off California in 1585 m, Gulf of California in 1200–1274 m, and Western Mexico in 2548 m; it resembles S. africana Augener, 1918 and S. andamanensis Sendall & Salazar-Vallejo, 2013 in having shields with a denticulate posterior margin; the latter two species live in shallow water and they differ from each other and from the new species by a combination of shield and papillae features. The fourth species, S. williamsae sp. n., was found off Oregon in 1000–2400 m, and off California in 878–1246 m; it resembles S. annenkovae because both species have shields with fans narrower than the anterior margin width, but differ in the relative development of shield features and in the relative size of prostomium and mouth; as stated above it also resembles S. maureri sp. n. but its shield has poorly-developed ribs, its median notch is distinct, and the lateral notches are poorly developed or indistinct. Keys to identify all species of Caulleryaspis and Sternaspis are also included.

Two new species of stone loaches of the genus Schistura from the Koladyne basin, Mizoram, India (Teleostei: Cobitoidei: Nemacheilidae)

Two new species of Schistura are described from the Koladyne basin of Mizoram, India. Schistura nebeshwari is distinguished from its congeners by the combination of the following characters: a prominent dorsal adipose crest on the caudal peduncle, 11-14 dark olivaceous bars on the body, the entire ventral surface of head with numerous small melanophores, an incomplete lateral line, three black spots at the dorsal-fin base, a complete prominent black basicaudal bar, lower jaw with a shallow median notch, and no suborbital flaps in males. Schistura scyphovecteta differs from its congeners by the combination of the following characters: six dark brown saddles, each one continuing to the flank, forming globular-shaped bars overlaying a background brown stripe along the lateral line, a complete lateral line, two black spots at the dorsal-fin base, an incomplete black basicaudal bar, no median notch on the lower jaw, and a suborbital flap present in males.

The larva of Drusus vinconi Sipahiler, 1992 (Trichoptera, Limnephilidae, Drusinae)

This paper describes the previously unknown larva of Drusus vinconi Sipahiler, 1992. Information on the morphology of the 5th larval instar is given, and the most important diagnostic features are illustrated. In the context of existing identification keys the larva of Drusus vinconi keys together with Drusus annulatus (Stephens, 1837), Drusus biguttatus (Pictet, 1834), Drusus ingridae Sipahiler, 1993, Hadimina torosensis Sipahiler, 2002 and Leptodrusus budtzi (Ulmer, 1913). These species differ in the contours of the pronotum in lateral view, the presence/absence of the pronotal transverse groove, the shape of the median notch of the pronotum (in anterior view), pronotal sculpturing, presence/absence of the lateral carina of the head capsule, the number of proximo-dorsal setae on the mid-and hind femora, where the lateral fringe starts on the abdomen, and in geographic distribution. With respect to zoogeography, Drusus vinconi is a (micro-)endemic of the Western Pyrenees. The species prefers stony substratum in springs and springbrooks of the montane and subalpine region (Graf et al. 2008; Sipahiler 1992, 1993). As a grazer, the larvae of Drusus vinconi feed on biofilm and epilithic algae.

Larval morphology of Dart-Poison Frogs (Anura: Dendrobatoidea: Aromobatidae and Dendrobatidae)

Tadpoles in the superfamily Dendrobatoidea (families Aromobatidae and Dendrobatidae), housed in zoological collections or illustrated in publications, were studied. For the most part, tadpoles of species within the family Aromobatidae, the subfamilies Colostethinae and Hyloxalinae (of the family Dendrobatidae), and those of the genus Phyllobates, Dendrobatinae (Dendrobatidae) have slender anterior jaw sheaths with a medial notch and slender lateral processes, triangular fleshy projections on the inner margin of the nostrils and digestive tube with constant diameter and color and its axis sinistrally directed, concealing the liver and other organs. These morphologies are different from the ones observed in tadpoles of species included in the Dendrobatinae (minus Phyllobates). Exceptions to these morphological arrangements are noted, being the digestive system arrangement and the nostril ornamentation more plastic than the shape of the upperjaw sheath. Tadpoles of all species of the Dendrobatoidea have similar disposition of digestive organs in early stages, but differentiate in late stages of development. Classifying the upper jaw sheath into the two recognized states is possible from very early stages of development, but gut disposition and nostril ornamentation cannot be determined until late in development, making classification and taxonomic assignment of tadpoles based on these morphological features challenging.

Distribution of Bone Mineral Density at Osteochondral Donor Sites in the Patellofemoral Joint Among Baseball Players and Controls

Background: To theoretically minimize complications of osteochondral graft harvest from the knee, grafts should be obtained from the site of lowest stress distribution across the joint. Hypothesis: Long-term stress distribution over the patellofemoral (PF) joint surface is not equal in athletes. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Measurement of subchondral bone density can determine long-term resultant stress acting on an articular surface in living joints. Our analysis was performed using computed tomography (CT) image data obtained from bilateral knees of 10 college baseball fielders (fielder group) and 10 college baseball pitchers (pitcher group) and 2 control groups, including 10 college soccer players (soccer group) and 10 nonathletes (nonathlete group). The distribution pattern of subchondral bone density throughout the articular surface of the PF joint was assessed using the CT osteoabsorptiometry method. The quantitative analysis focused on the location of the low-density area at the articular surface to assess potential osteochondral donor sites. Results: All participants in the pitcher and fielder groups demonstrated a low-density area widely distributed in the proximal part of the lateral trochlea. On the other hand, a high-density area was located in the distal part of the lateral notch, of the medial notch, and of the medial trochlea. No apparent differences in the distribution pattern were found between the baseball groups and the control groups. Conclusion: Our analysis, based on CT osteoabsorptiometry, indicates that the proximal lateral trochlea of the distal femur has the highest percentage area of low bone density at the PF joint level in donor knees of baseball players, soccer players, and nonathlete controls. Clinical Relevance: From a biomechanical viewpoint, the proximal lateral trochlea is the optimal site for harvesting osteochondral grafts in performing mosaicplasty for baseball players. This selection for the donor site may minimize postoperative PF joint symptoms.

First tyrannosaurid remains from the Upper Cretaceous "El Gallo" Formation of Baja California, México

We report a complete left fourth metatarsal collected from rocks of the Upper Cretaceous (Campanian) “El Gallo” Formation exposed along the Pacific Ocean near El Rosario, Baja California, Mexico. The metatarsal IV was part of an arctometatarsalian metatarsus, as evidenced by a deep medial notch proximally and extensive articulation for metatarsal III. This condition, along with the U-shape of the proximal end, supports identification as tyrannosauroid. It is assigned to Tyrannosauridae based on features on the posterior surface of the shaft, but finer taxonomic resolution is not possible. Compared to other tyrannosauroids, the metatarsal is relatively short, closely resembling the proportions of the gracile Albertosaurus sarcophagus rather than the much more massive, robust metatarsals of Tyrannosaurus rex. The Baja tyrannosaurid metatarsal is shorter than almost all other tyrannosauroid fourth metatarsals, raising the possibility that it pertains to an immature individual. North American tyrannosauroids ...

Tadpole and Breeding Habitats ofChiasmocleis shudikarensis(Anura, Microhylidae) in Central Amazonia, Brazil

ABSTRACT. In this study we describe the tadpoles of Chiasmocleis shudikarensis based on 37 individuals and 14 development stages. The tadpole of C. shudikarensis is characterized by small size (15.6 mm total length in stage 36), body rectangular in dorsal view, oval in lateral view; eyes lateral; nostrils absent; tail triangular, gradually diminishing to a pointed tip; spiracle long and wide, its distal border projecting over the anal tube and with finger-shaped projections; mouth small and terminal with marginal papillae and jaw sheaths absent; upper lip narrow, fleshy, covering the oral opening; lower lip narrow with a U-shaped medial notch. We also provide comments on spawning sites and breeding period.

A new cave-dwelling loach, Triplophysa macrocephala (Teleostei: Cypriniformes: Balitoridae), from Guangxi, China

A new cave-dwelling species, Triplophysa macrocephala sp. nov. is described based on specimens collected from a karst cave in Renguang village, Lihu Town, Nandan County, Guangxi Zhuang Autonomous Region, China. The new species can be distinguished from its congeners by possessing the following combination of characters: pectoral fin not reaching beyond pelvic-fin origin; caudal fin forked; body smooth or scaleless; dorsal-fin origin anterior to pelvic-fin origin, edge of dorsal fin truncate; dorsal fin with eight branched rays; anal fin with five branched rays; eye small and vestigial; lower jaw arched with a median notch; air-bladder wrapped in bony capsule, lateral enlarged, posterior chamber of air-bladder degenerated.

3D-anatomy of a new tropical Peruvian nudibranch gastropod species, Corambe mancorensis, and novel hypotheses on dorid gill ontogeny and evolution

Nudibranch molluscs of the genus Corambe differ from most other Doridoidea by having ventral rather than dorsal anus and gills. Because of these and other features, such as separate cerebral and pleural ganglia, corambids have been considered as an archaic or enigmatic group. The first tropical eastern Pacific Corambe species is described in morphological and some histological detail. Selected organs such as circulatory and central nervous features are reconstructed from serial semithin histological slides and visualized in three dimensions using Amira software. Anatomical findings include two separate ganglia on the visceral loop and an additional ganglion on the right side of the body that is connected to the pedal ganglion. Corambe mancorensis n. sp. is dorsoventrally depressed, has an oval, fleshy notum covered with a cuticle, and has a wide posterior medial notch that can be closed completely by unique lobules. Gills are arranged in an unusual horseshoe-like manner including both phanerobranch anal (=medial) gills and corambid lateroventral gill rows, and are connected to the atrium by a complex vessel system. The three medial gills arise from a posterodorsal gill cavity within the notal notch, similar to the case in Corambe evelinae Marcus, 1958. By scanning electron microscopy a vestigial gill cavity is also detectable in C. pacifica MacFarland & O'Donoghue, 1929, but here it is situated ventrally. Our new information on adult corambids is compared with new and published ontogenetic data on phanerobranch and cryptobranch dorids, to contribute to a novel interpretation of the ontogeny of dorid mantle and gill complexes. The progenetic evolution of corambids ‘recapitulates’ early juvenile dorid stages – turning Haeckel's Law upside down.

Rediscovery of the Rare Pilumnid Crab, Actumnus Simplex Rathbun, 1911 (Decapoda, Brachyura) and a New Record for the Persian Gulf

AbstractActumnus simplex Rathbun, 1911, described 100 years ago and never reported again since, is recorded for the first time from the Persian Gulf. The species is characterized by a prominently convex dorsal carapace surface, regions that are weakly defined, four serrated anterolateral teeth, and a gently serrated frontal margin with a distinct median notch. It is morphologically close to Neoactumnus convexus Sakai, 1965, and N. unispina Garth & Kim, 1983, both from the western Pacific, but is easily distinguishable by possessing a distinct median notch in the frontal margin.

A new early dinosaur (Saurischia: Sauropodomorpha) from the Late Triassic of Argentina: a reassessment of dinosaur origin and phylogeny

It was traditionally thought that the oldest known dinosaur assemblages were not diverse, and that their early diversification and numerical dominance over other tetrapods occurred during the latest Triassic. However, new evidence gathered from the lower levels of the Ischigualasto Fm. of Argentina challenges this view. New dinosaur remains are described from this stratigraphical unit, including the new species Chromogisaurus novasi. This taxon is distinguished from other basal dinosauriforms by the presence of proximal caudals without median notch separating the postzygapophyses, femoral lateral surface with deep and large fossa immediately below the trochanteric shelf, and metatarsal II with strongly dorsoventrally asymmetric distal condyles. A phylogenetic analysis found Chromogisaurus to lie at the base of Sauropodomorpha, as a member of Guaibasauridae, an early branch of basal sauropodomorphs composed of Guaibasaurus, Agnosphitys, Panphagia, Saturnalia and Chromogisaurus. Such an affinity is for the first time suggested for Guaibasaurus, whereas Panphagia is not recovered as the most basal sauropodomorph. Furthermore, Chromogisaurus is consistently located as more closely related to Saturnalia than to any other dinosaur. Thus, the Saturnalia + Chromogisaurus clade is named here as the new subfamily Saturnaliinae. In addition, Eoraptor is found to be the sister-taxon of Neotheropoda, and herrerasaurids to be non-eusaurischian saurischians. The new evidence presented here demonstrates that dinosaurs first appeared in the fossil record as a diverse group, although they were a numerically minor component of faunas in which they occur. Accordingly, the early increase of dinosaur diversity and their numerical dominance over other terrestrial tetrapods were diachronous processes, with the latter preceded by a period of low abundance but high diversity.

A cladistic revision of Tortopus Needham & Murphy with description of the new genus Tortopsis (Ephemeroptera: Polymitarcyidae)

The 12 species previously placed in Tortopus together with 3 species newly described here, are revised and included in a phylogenetic analysis. Based on synapomorphic characters on the nymphs and adults of both sexes, Tortopus is restricted to T. igaranus Needham & Murphy, T. circumfluus Ulmer, T. harrisi Traver, T. zottai (Navás), T. bellus Lugo-Ortiz & McCafferty, and T. arenales sp. nov., and the genus is defined by: female parastyli receptors with long furrows anterior to sockets; penes entirely flattened; male ninth abdominal sternum almost separated in two portions by a median notch; mesosternum with furcasternal protuberances contiguous only on basal corner; and nymphs with two subapical tubercles on mandibular tusks. Tortopsis is newly described for T. bruchianus (Navás), T. limoncocha sp. nov., T. obscuripennis (Domínguez), T. parishi (Banks), T. primus (McDunnough), T. puella (Pictet), T. sarae (Domínguez), T. spatula sp. nov., and T. unguiculatus (Ulmer). Tortopsis is characterized by: R sector of female fore wing without additional veins between R 2 and IR; female parastyli receptors C or V-shaped, with sockets opening towards median line; male gonopore associated with a claw-like structure; penes separated from the base; parastyli more than 5 times length of pedestals; parastyli curved in lateral view; nymphs with a single subapical tubercle on mandibular tusks. The study of available type material permitted inclusion of comparative diagnoses, with figures and redescriptions as needed. The male imago of the type species of Tortopus (T. igaranus Needham & Murphy) is described for the first time, as are the female adults of Tortopus bellus Lugo-Ortiz & McCafferty and T. harrisi Traver. Three new Neotropical species based on male and female adults are described: Tortopus arenales and Tortopsis limoncocha from Ecuador, and Tortopsis spatula from Colombia. Keys to separate the adults and nymphs of the genera of Polymitarcyidae, and for male and female adults of all the species of Tortopus and Tortopsis are presented, as well as line drawings, pictures and SEM photographs of important structures.

Threatened fishes of the world: Alosa alabamae (Jordan and Evermann, 1896) (Clupeidae)

Common names: Alabama shad, Gulf shad. Conservation status: US National Marine Fisheries Service Species of Concern, AFS: Vulnerable; IUCN: Endangered. Identification: Upper jaw median notch, protruding lower jaw, one row tongue teeth, 41–48 rakers on lower anterior gill arch; no dorsal filament. Silver with black spots on lower jaw; greenish-blue dorsally. Females 36–46 cm, males 9–42 cm SL. Distribution: Euryhaline, anadromous, schooling; spawns in medium to large rivers from the Mississippi River drainage to the Suwannee River, Florida (Mettee and O’Neil 2003); extirpated from at least 8 of the 14 native states (Mettee and O’Neil 2003). Abundance: Once commerically harvested, now rare (Mettee and O’Neil 2003); largest remaining population occurs in the Apalachicola River, Florida (Barkuloo et al. 1993). Habitat and ecology: Juveniles are found in rivers for their first 6–8 months, eat fishes and invertebrates. Diurnally, small juveniles use sandbars, then switch to open channels and steep bank habitat; they select cooler temperatures (Mickle 2006). Little is known of their ecology in marine environments. Juveniles enter the Gulf of Mexico from late summer to early winter. Spawning starts primarily at age 2 and live 6 years (Mettee and O’Neil 2003). Reproduction: Broadcast spawn spring/early summer at 18–238C over coarse sand and gravel in moderate currents; no foraging during spawning (Mills 1972). Arrival time varies by sex and age (Mette and O’Neil 2003), return to sea after spawning (Barkuloo et al. 1993). Some homing and genetic differences among drainages (Bowen 2005). Threats: Dams block spawning access and alter hydrology and substrates (Adams et al. 2000; Mettee and O’Neil 2003); poor water quality, siltation, altered habitat and thermal regimes, dredging, and perhaps bycatch in marine fisheries. Conservation recommendations: Implement effective fish passage; restore hydrologic regimes. Research into the marine phase including migrations, feeding and bycatch; and spawning, rearing, and other habitat needs. Remarks: Allopatric species pair with A. sapidissima. D. W. Meadows (&) Office of Protected Resources F/PR3, National Marine Fisheries Service, 1315 East West Highway, Silver Spring, MD 20910, USA e-mail: Dwayne.Meadows@noaa.gov

Two new species of the sisorid Genus Oreoglanis Smith from Yunnan, China (Teleostei: Sisoridae)

Two new species of the genus Oreoglanis, O. jingdongensis and O. immaculatus are described from the Mekong and Salween River basins, respectively, of Yunnan Province, China. Oreoglanis jingdongensis can be distinguished from other Oreoglanis species by the following characters: lower lip with a distinct median notch, posterior edge smooth or with indentations; caudal fin lunate and lower lobe longer than upper lobe. Oreoglanis immaculatus can be distinguished from its congeners by the following features: lower lip with a strait median notch, posterior edge with indentations; caudal fin emarginate and lower lobe about the same length as upper lobe, having no yellow patches on sides of body below adipose fin.

Two New Species of the Neotropical Catfish GenusLepthoplosternum(Ostariophysi: Siluriformes: Callichthyidae)

Abstract Two new species of the callichthyid catfish genus Lepthoplosternum are described from the Amazon region. Lepthoplosternum stellatum is described from a tributary of Lago Tefe, Amazonas, Brazil, and it is diagnosed from other Lepthoplosternum species by a unique combination of characters: lower lip with pointed, crenulate, triangular fleshy projections lateral to the medial notch, caudal peduncle comparatively shallow (15.7–18.9% SL), and dorsal fin usually with one unbranched and seven branched rays. Lepthoplosternum ucamara is described from the Pacaya-Samiria National Reserve in the lower Ucayali River, Loreto, Peru, and can be diagnosed from other Lepthoplosternum species by the following unique combination of characters: lower lip with short, rounded projections, caudal peduncle comparatively shallow (15.2–17.7% SL), and dorsal fin with two unbranched and six branched rays. The distribution of Lepthoplosternum altamazonicum is extended to include the varzea floodplains of the Solimoes River a...

Uma nova espécie de Dadayius Fukui, 1929 (Digenea: Cladorchiidae) parasita do trato intestinal de Metynnis maculatus (Kner, 1858) (Characidae) da planície de inundação do alto rio Paraná, Brasil

A new species of Cladorchiidae (Trematoda, Digenea) was found in the intestinal tract of freshwater fish “pacu peva”, Metynnis maculates (Kner, 1858) from the Upper Paraná River floodplain, southern Brazil. The new species was classified in the genus Dadayius Fukui, 1929 by having non-lobate testis and a ventro-terminal acetabulum with postero median notch on rim, characters of the genus wich has only two previously known species. Some characters that differ the new species from D. marenzelleri (Daday, 1907) and D. pacuensis Thatcher, 1996 are: ceca not reaching acetabulum, vitellaria of limited extension, not reaching the level of posterior testis and the presence of two different egg sizes in two different maturity stages.

Functional morphology of sexually selected gentalia in the water strider Aquarius remigis

In the water strider Aquarius remigis (Say), sexual selection favours males with longer genitalia. We used video analysis plus light and scanning electron microscopy to examine the structure, movement, and articulation of the genitalia as a first step in determining the functional basis of this selection. Male A. remigis are characterized by long, robust genital segments; a marked ventral median notch in the posterior margin of the pregenital segment; an enlarged phallus tipped with a uniquely prolonged sclerotized plate; and a large, spine-covered, membranous lobe that inflates within the female's reproductive tract. Detailed examinations of genital interactions prior to and during copulation allow us to deduce the functional significance of these distinguishing traits. We postulate that by increasing the length, mobility, strength, and rigidity of the phallus, the first three traits increase the ability of males to achieve intromission in spite of active female resistance, and to maintain intromission during the prolonged copulations characteristic of this species. Inflation of the large, spinous lobe probably contributes to the latter function, and may also directly affect fertilization success by displacing or damaging sperm from previous males. We discuss these interpretations in the context of current theories of genitalic coevolution and sexual conflict in the Gerridae.