Pair Of Pits Research Articles

Implementation of pumped hydro/photovoltaic systems in mining-degraded areas: a case study in Quadrilátero Ferrífero, Minas Gerais, Brazil

This work presents a proposal for the transformation of mining-degraded areas into renewable energy installations, converting deactivated mine pits, in the Quadrilátero Ferrífero (QF) region in state of Minas Gerais (MG), Brazil, into reservoirs for Pumped Storage Hydropower (PSH). Additionally, it proposes the alteration of adjacent areas impacted by mining extraction process, through their conversion into Photovoltaic Power Plants (PV). This measure has the potential to turn mining liabilities into sources of energy with lower environmental impact and sustainability for society. This process allows energy to be stored in the form of hydraulic batteries, which can mitigate the effects of intermittency of photovoltaic generation in the electrical grid. The presented methodology involves mapping deactivated mines, calculating the energy potential of the coupled PSH and PV systems, and conducting an economic feasibility study for PSH implementation. The work includes a case study discussing potential local environmental impacts and the energy potentials of this solution. The case study resulted in identifying a suitable pair of mine pits for a PSH in the QF, capable of supplying the electrical grid with approximately 234.3 MW, with the generated energy cost ranging between U$112.26/MWh to U$167.22/MWh. It is concluded that utilizing inactive mines as PSH reservoirs and installing PV in adjacent mining-degraded areas are innovative and technologically feasible strategies. Economically, their implementation will depend on the market price of energy.

Aenigmaphes gen. n., a new glandulariine genus of the Australian region (Coleoptera: Staphylinidae: Scydmaeninae).

Aenigmaphes gen. n. is described for a New Guinean Aenigmaphes papuanus sp. n. The new genus is characterized by several unique features, among others, by the pronotum with one pair of adjacent antebasal pits at middle, both situated in a deep median longitudinal groove, and the posterior margin of each mesocoxal rest demarcated by a step-wise ridge, which extends laterad and is bent posterad to connect with the lateral metaventral margin far behind the mesocoxae. The adult of the new species is minute, wingless and microphthalmous, which may be adaptations to subterranean life. Females of an undescribed species of Aenigmaphes are also recorded from Sulawesi. Relationships of the new genus within Glandulariini remain unclear.

Two species previously placed in Euconnus s. str. belong in the endemic Madagascan subgenus Glabriconnus (Coleoptera: Staphylinidae: Scydmaeninae)

Abstract The Madagascan species Euconnus andringitrae Franz, 1986 and E. berentyensis Franz, 1986 are redescribed and transferred from Euconnus s. str. to the subgenus Glabriconnus Jałoszyński, 2016. They share with E. (Glabriconnus) aterrimus Franz, 1986 the evenly convex frons and vertex, and lack of a pair of diffuse longitudinal carinae (present in all remaining species of Glabriconnus), and with E. (Glabriconnus) andranomenaus Jałoszyński, 2016 the presence of two distinct hypomeral grooves (one variously distinct groove in remaining Glabriconnus species). The unique character for Euconnus andringitrae and E. berentyensis is the transverse antebasal groove connecting a pair of lateral pits, which was not previously known in any other Glabriconnus. Consequently, the diagnosis of Glabriconnus is here emended to include a considerable variability in pronotal structures. The distribution of Glabriconnus in Madagascar is summarized.

A new millipede (Diplopoda, Helminthomorpha) from the Middle Triassic Luoping biota of Yunnan, Southwest China

AbstractA new helminthomorph millipede,Sinosoma luopingensenew genus new species, from the Triassic Luoping biota of China, has 39 body segments, metazonites with lateral swellings that bear a pair of posterolateral pits (?insertion pits for spine bases), and sternites that are unfused to the pleurotergites. This millipede shares a number of characters with nematophoran diplopods, but lacks the prominent dorsal suture characteristic of that order. Other “millipede” material from the biota is more problematic. Millipedes are a rare part of the Luoping biota, which is composed mainly of marine and near-shore organisms. Occurrences of fossil millipedes are exceedingly rare in Triassic rocks worldwide, comprising specimens from Europe, Asia, and Africa, and consisting of juliform millipedes and millipedes that are either nematophorans or forms very similar to nematophorans.

Olfactory organ of Octopus vulgaris: morphology, plasticity, turnover and sensory characterization.

ABSTRACTThe cephalopod olfactory organ was described for the first time in 1844 by von Kölliker, who was attracted to the pair of small pits of ciliated cells on each side of the head, below the eyes close to the mantle edge, in both octopuses and squids. Several functional studies have been conducted on decapods but very little is known about octopods. The morphology of the octopus olfactory system has been studied, but only to a limited extent on post-hatching specimens, and the only paper on adult octopus gives a minimal description of the olfactory organ. Here, we describe the detailed morphology of young male and female Octopus vulgaris olfactory epithelium, and using a combination of classical morphology and 3D reconstruction techniques, we propose a new classification for O. vulgaris olfactory sensory neurons. Furthermore, using specific markers such as olfactory marker protein (OMP) and proliferating cell nuclear antigen (PCNA) we have been able to identify and differentially localize both mature olfactory sensory neurons and olfactory sensory neurons involved in epithelium turnover. Taken together, our data suggest that the O. vulgaris olfactory organ is extremely plastic, capable of changing its shape and also proliferating its cells in older specimens.

SEM studies on acanthocephalan parasite, Echinorhynchus veli infecting the fish Synaptura orientalis (Bl & Sch, 1801).

Echinorhynchus veli (George and Nadakal, 1978), an acanthocephalid worm infesting the estuarine flat fish, Synaptura orientalis, was collected from the Veli lake, Kerala. The parasite was recovered from the intestine of the host fish. The detailed surface morphology was studied with the help of scanning electron microscope. The study revealed a cylindrical, medially swollen proboscis with a flat apex, backward directed hooks, each with smooth surface, broad base, pointed tip and an epidermal elevation at the point of insertion. A pair of sensory pits was seen at the base of the proboscis. The neck was well developed with densely packed epidermal micropores. Paired sensory pits were seen at the base of the neck and a collar between it and the trunk. The epidermis of the trunk has microtriches and micropores. The female genital pore was circular, and terminal in an elevated orifice. In male, the copulatory bursa was directed ventrally, with well-defined rim and several sensory papillae.

Taxonomy of 'Euconnus complex'. Part VII. Glabriconnus, a new subgenus of Euconnus from Madagascar (Coleoptera, Staphylinidae, Scydmaeninae).

A new subgenus of Euconnus Thomson is described, Glabriconnus subgen. n., to accommodate four Madagascan species: Euconnus banari sp. n. (type species of Glabriconnus), E. andranomenaus sp. n., E. februarius sp. n. and E. aterrimus Franz (transferred from Euconnus s. str.). Morphological structures of the new taxa are illustrated and described in detail, and possible relationships of Glabriconnus are discussed. The new subgenus is most similar to Tetramelus Motschulsky and Paratetramelus Franz in gradually thickened antennae and reduction of wings and associated structures, but the four species included in Glabriconnus share a unique synapomorphy, a hypomeral groove at each side of pronotum. They also have a broad, short and flattened 'anthiciform' head; nearly glabrous head, pronotum and elytra, except for thick bristles on genae, postgenae (but not tempora) and along anterior and lateral pronotal margins, and pronotum with one pair of distinct lateral pits.

Depreissia decipiens, an enigmatic canopy spider from Borneo revisited (Araneae, Salticidae), with remarks on the distribution and diversity of canopy spiders in Sabah, Borneo.

Depreissia is a little known genus comprising two hymenopteran-mimicking species, one found in Central Africa and one in the north of Borneo. The male of Depreissia decipiens is redescribed, the female is described for the first time. The carapace is elongated, dorsally flattened and rhombus-shaped, the rear of the thorax laterally depressed and transformed, with a pair of deep pits; the pedicel is almost as long as the abdomen. The male palp is unusual, characterized by the transverse deeply split membranous tegulum separating a ventral part which bears a sclerotized tegular apophysis and a large dagger-like retrodirected median apophysis. The female epigyne consists of one pair of large adjacent spermathecae and very long copulatory ducts arising posteriorly and rising laterally alongside the spermathecae continuing in several vertical and horizontal coils over the anterior surface. Relationships within the Salticidae are discussed and an affinity with the Cocalodinae is suggested. Arguments are provided for a hypothesis that Depreissia decipiens is not ant-mimicking as was previously believed, but is a mimic of polistinine wasps. The species was found in the canopy in the Kinabalu area only, in primary and old secondary rainforest at 200–700 m.a.s.l. Overlap of canopy-dwelling spider species with those in the understorey are discussed and examples of species richness and endemism in the canopy are highlighted. Canopy fogging is a very efficient method of collecting for most arthropods. The canopy fauna adds an extra dimension to the known biodiversity of the tropical rainforest. In southeast Asia, canopy research has been neglected, inhibiting evaluation of comparative results of this canopy project with that from other regions. More use of fogging as a collecting method would greatly improve insight into the actual species richness and species distribution in general.

Beetles (Coleoptera) of Peru: A Survey of the Families. Erotylidae Latreille, 1802

Diversity in Peru: 5 subfamilies, 41 genera, 303 species. Recognition: The common name for Erotylidae is the “Pleasing fungus beetles” due to the attractive adult coloration and mycophagous habits of many species. Erotylidae, including Languriidae, “Lizard beetles”, form a monophyletic group that is supported by phylogenetic analyses using morphological (e.g., Wegrzynowicz, 2002; Leschen and Buckley, 2007) and molecular (e.g., Robertson et al., 2004) data. Beetles in the erotylid familial clade may be recognized by the following combination of derived features: subocular glandular ducts present, supraocular line present, pronotal lateral carina simple, procoxal cavities with lateral extensions, trochantinal notch present, mesocoxal cavities laterally closed by metaventrite, and aedeagus laterally compressed with relatively long struts on penis (Leschen et al., 2010). Adults of Peruvian erotylids are 1.2–23.0 mm. long and range in body form from parallel-sided to oval. The base of the prothorax is not conspicuously narrower than the elytral bases. They vary in convexity from being dorso-ventrally flattened to having a hemispherical form. In some species (e.g., Gibbifer spp.) the elytra are highly vaulted. The dorsal surfaces are typically smooth and either glabrous or have fine setae. Erotylids bear fine pores for glandular ducts on many structures, especially the prothoracic lateral carina, genae, mentum, thoracic ventrites, and around the eyes. The antennae are 11-segmented and capitate. The club is flattened and 3–6 segmented. The mandibles are short and broad with a bidentate or tridentate apex and a well-developed mola and prostheca. The maxillae have a well-developed galea and lacinia. The terminal segment on the maxillary and labial palpi varies from fusiform to being strongly expanded and truncate apically. The pronotum usually has a smooth lateral margin and a complete carina with a raised margin or bead. The anterior lateral pronotal angles are either produced forward or simple, the posterior angles are not produced. The posterior margin is usually evenly rounded, but a mesal lobe occurs in some. The pronotal disc is typically smooth, but at the base there may be a pair of weak basal impressions, a pair of pits, or a transverse depression. The scutellum is visible dorsally and usually broadly rounded or broadly pentagonal. The elytra have striate to confused punctation. A scutellary striole may be present or absent. The epipleura are usually complete to apex. The procoxae do not project ventrally. The procoxal cavities are slightly transverse or circular and externally open or closed. Protrochantins are not exposed. The

Larval morphology of Scydmaenus tarsatus and S. hellwigii, with notes on feeding behaviour and a review of the bibliography on the preimaginal stages of ant-like stone beetles (Coleoptera: Staphylinidae: Scydmaeninae)

Morphology of mature larvae of two Central European species of Scydmaenus Latreille is described and illustrated: S. (s. str.) tarsatus Muller & Kunze and S. (Cholerus) hellwigii (Herbst). Inaccuracies in previous descriptions of S. tarsatus are discussed and the following combination of characters is defined as diagnostic for Scydmaenus: epicranial sutures reaching posteromedian margins of antennal insertions; presence of a single pair of stemmata and epicranial supraantennal pits; anterior row of subtriangular teeth on epipharynx; mandibles falciform and without mesal teeth; antennomere 3 rudimentary; antennal sensory appendage subconical and asymmetrical; maxilla with galea and lacinia; labium strongly constricted between mentum and prementum; thoracic tergites undivided along midline; head capsule, thoracic tergites, laterotergites and abdominal segments except sternite 1 densely setose; thoracic sternites and abdominal sternite1 largely asetose; and lack of urogomphi. We also describe the feeding behaviour of immature S. tarsatus and demonstrate for the first time that Scydmaeninae larvae can feed on live springtails and not armoured mites. In the introduction we provide a summary of the literature on all hitherto known preimaginal stages of Scydmaeninae.

Preliminary quantification of a shape model for etch-pits formed during natural weathering of olivine

Abstract Many etch-pits on olivine grains occur as a pair of cone-shaped pits sharing a base, which consequently appear as diamond-shaped etch-pits in cross-section. Quantitative image analysis of back-scattered electron images establishes empirical dimensions of olivine etch-pits in naturally weathered samples from Hawaii and North Carolina. Images of naturally etched olivine were acquired from polished thin-sections by scanning electron microscopy. An average cone-radius-to-height ratio ( r : h ) of 1.78 was determined for diamond-shaped cross-sections of etch-pits occurring in naturally weathered olivine grains, largely consistent with previous qualitative results. Olivine etch-pit shape as represented by r : h varies from slightly more than half the average value to slightly more than twice the average. Etch-pit shape does not appear to vary systematically with etch-pit size.

Infrared-sensitive pit organ and trigeminal ganglion in the crotaline snakes

The infrared (IR) receptors in the pit organ of crotaline snakes are very sensitive to temperature. The sensitivity to IR radiation is much greater in crotaline snakes than in boid snakes because they have a thermosensitive membrane suspended in a pair of pits that comprise the pit organ. The vasculature of the pit membrane, which is located near IR-sensitive terminal nerve masses, the IR receptors, supplies the blood necessary to provide cooling and the energy and oxygen that the IR receptors require. The ophthalmic and maxillary branches of the trigeminal nerve innervate the pit membrane. In crotaline snakes, the trigeminal ganglion (TG) is divided into the ophthalmic and maxillomandibular ganglia; a prominent septum further separates the two divisions of the maxillomandibular ganglion. The TG neurons in the ophthalmic ganglion and the maxillary division of the maxillomandibular ganglion relay IR sensation to the brain. This article reviews the IR-sensitive pit organ and trigeminal sensory system structures in crotaline snakes.

Dislocation motions in C60 crystals by an indentation test

We investigated dislocation motions in C60 crystals after indentation, by x-ray topography and etching method. A rosette pattern was observed around an indentation after etching. The dislocations in the rosette were moved by thermal annealing and the positions in the dislocations were measured before and after annealing by the double etching method. The annealing temperature dependence of dislocation motions was measured in the temperature range 490–610 K. The characteristics of dislocation motion showed dislocation locking due to impurity atmosphere. It was concluded that oxygen and oxide of C60 molecules could lock the dislocations. Moreover, a pair of pits in the rosette pattern were observed after annealing. It corresponded to a pair of Shockley's partial dislocations.

Tantulum elegans reloaded: a computer‐based 3D‐visualization of the anatomy of a Caribbean freshwater acochlidian gastropod

Abstract. Acochlidian gastropods combine several aberrant biological and morphological features. The poorly known Caribbean Tantulum elegans is one of the few opisthobranch species inhabiting a freshwater system, and the only one found in muddy interstices of a Caribbean mountain spring swamp. Morphological details of this tiny species were either unknown or not fully reliable, especially with regard to the complex central nervous and reproductive systems. We critically re‐examined original paratype section series and prepared semi‐thin serial sections of two additional paratypes. All organ systems were three‐dimensionally reconstructed using AMIRA software. Our results show several discrepancies from the original description: the pharynx is a complex system of different muscles, but similar to that of other acochlidian species; the circulatory system shows a two‐chambered heart; in the nervous system there are separate optic and rhinophoral ganglia, the latter innervating a pair of small sensory pits we assume to be Hancock's organs, and large aggregations of precerebral accessory ganglia were found. Nephropore, anus, and female gonopore open dextroventrally. To our surprise, adults of T. elegans are sequential hermaphrodites with an unusual androdiaulic reproductive system and a well‐developed cephalic penial complex. In T. elegans, there is a mix of character conditions found in different genera, e.g., Pseudunela and Asperspina. The phylogenetic position of T. elegans still remains unclear.

Life-cycle stage morphology of Psoroptes mange mites.

Detailed life-cycle stage descriptions for the ectoparasitic mite Psoroptes ovis (Hering) (Acari: Psoroptidae) from rabbit hosts (syn. Psoroptes cuniculi) are presented. The results resolve a number of contradictions in the literature relating to the recognition of the life cycle stages of these mites. This study supports the view that there are two distinct male nymphal stages, both lacking dorsoposterior tubercles. The male tritonymph is significantly larger than the protonymph and has five pairs of metapodosomal setae rather than three. In addition, male tritonymphs have two pairs of cuticular pits on the central metapodosoma rather than the single pair of the protonymph. The results also show that the female protonymph can be distinguished from the male nymphal stages and the female tritonymph. Both female nymphal stages possess dorsoposterior tubercles, but the protonymph is significantly smaller than the tritonymph. In addition, the protonymph possesses three pairs of metapodosomal setae rather than five, one pair of cuticular pits rather than two, and a pulvillus on leg IV which is absent in the female tritonymph. The presence of dorsoposterior tubercles enables the female nymphs to be distinguished easily from the males. By contrast, distinguishing between the nymphal stages of the same sex relies on the identification of both the number of metapodosomal setae and cuticular pits. These descriptions are used to produce a key, which allows the various stages of both sexes to be distinguished.

Nuchal Organs of the Polychaete Parapionosyllis manca (Syllidae)

Nuchal are known to be important sensory of many polychaete annelid species. This study describes the fine structure of the nuchal and associated glands of Parapionosyllis manca. In each nuchal organ, the epithelium of the nuchal cleft encloses an olfactory chamber through which sensory cilia and microvillus-like processes radiate. These sensory components originate from bulbs of sensory cells that are closely associated to form a sensory bundle. Each bundle of cells is encased in a palisade of support cells bearing motile cilia. Numerous secretory vesicles occur in the cytoplasm of the support cells and beneath the modified cuticle of the nuchal organ. The support cells of the olfactory region extend posteriorly to form the nuchal lobes, or glands. The cells are elongate and taper to a thin neck just before leaving the sensory area of the nuchal organ. There are essentially no nuclei in the sensory region as these and most of the other cellular organelles are concentrated in the lobes that extend into the body cavity but are contained by the epidermal basement matrix. The nuchal organ is innervated by the nuchal nerve, which extends posteriorly from the hind portion of the brain. Additional key words: ultrastructure, sensory organs, Annelida The nuchal of polychaete annelids are a pair of pits located in the head region of the animal, usually between the prostomium and the peristomium. They are believed by most investigators to be chemosensory (Lang 1888; Rolleston & Jackson 1888; Rullier 1950, 1951; Bullock & Horridge 1965; Purschke 1986, 1990; Schlotzer-Schrehardt 1986; Rhode 1989, 1990) and probably function in the location of food. Others believe the may also have a role in coordinating reproductive behavior (Schlotzer-Schrehardt 1987). The present study describes the nuchal of Parapionosyllis manca, an interstitial polychaete belonging to the family Syllidae. The nuchal organ, found in many families of polychaetes with varying lifestyles, was first described in 1849 by J.H. Huxley while on an expedition aboard the H.M.S. Rattlesnake. He collected two specimens of Tomopteris onisciformes (Tomopteridae) and noted the presence of a pair of rounded elevations running back along the dorsal surface in the form of a band or ridge between the narrow neck and the second pair of cephalic appendages. This information was published by Carpenter (1859). A year later, the were more a To whom correspondence should be addressed. Present address: Dept. of Companion Animal and Special Species Medicine, North Carolina State University, College of Veterinary Medicine, Raleigh, NC 27606, USA. accurately described by Carpenter & Claparede (1860), and were called ciliated epaulettes. Several decades later workers began to speculate on the function of nuchal organs. Lang (1888) referred to nuchal as of smell. Rolleston & Jackson (1888) stated that among their organs of special sense, many polychaetes had grooves supplied by nerves from the cerebral ganglia. Malaquin (1893) considered the nuchal of syllids to be sense responsive

Morphological and behavioural development of halibut, Hippoglossus hippoglossus (L.) larvae

Live yolk‐sac halibut, Hippoglossus hippoglossus (L.) larvae from rearing experiments at Austevoll Aquaculture Station, Norway, were examined from hatching to past first feeding for developmental morphology and behaviour. The findings include development of the respiratory and circulatory organs, eye pigmentation, mouth formation, organs of the digestive system and the process of yolk absorption, as well as swimming speed and activity levels.A stomodeum is not present at hatching although drinking is possible through a pair of branchial pits which gradually develop into the operculum and gill basket. The mouth normally opens slowly, the gape being restricted by a transverse septum until bones are formed. The amount of time spent swimming varies from less than 15% of the observation period during the first 2 weeks after hatching to between 70 and 100% around the seventh week after hatching, when individual differences become more apparent. Larvae generally react with a burst of swimming when two come into contact. Speed and duration of swimming seems to be correlated with development of eye pigment, heart size and fin formation. The yolk‐sac period is divided into four stages.

DESCRIPTIONS OF A NEW GENUS AND TWO NEW SPECIES OF PSELAPHINI (COLEOPTERA, PSELAPHIDAE) FROM JAPAN AND TAIWAN

A new genus Hirashimanymus of the tribe Pselaphini (Pselaphidae, Pselaphinae) and two new species H. schistodactyroides and H. babai are described and illustrated from southwest Japan and Taiwan. This paper presents a new genus of the tribe Pselaphini and two new species from Ishigaki Is., southwest Japan and Taiwan. The name of the new genus is dedicated with gratitude to Prof. Emer. Yoshihiro Hirashima for his continuous encouragement and guidance. Hirashimanymus gen. nov. Type species : Hirashimunymus schistodactyroides sp. nov. Body medium-sized, broadened posteriorly, coarsely punctate in dorsal surface. Head weakly narrowed anteriorly, clypeogenal areas weakly laminate, frons broadly nodulate, vertex broad, with a pair of indistinct dorsal tentorial pits ; eyes ovoid, convex ; antennae elongate, very irregularly segmented in length, densely with coarse punctures, each segment subcylindrical ; maxillary palpi 3-segmented, 3rd segment largest, thick and rounded in basal part, tapered toward apex, with a short spine or denticle. Pronotum round-sided, simple on dorsal surface ; elytra broadened posteriorly, humeri weakly expanded in male, almost flat in female, each elytron with 4 basal foveae ; hind wing developed in male, reduced in female ; legs slender, femora densely with coarse punctures, tibiae slender, each with a few suberect hairs, tarsi large, 3rd segment largest, lobate and rounded in ventroapical part, with a large, scythe-shaped claw. Abdomen shorter than elytra, 4th segment largest, with a transverse groove in basal part, 5th to 8th segments shortened successively. The genus Hirashimanymus nov. is classified into the tribe Pselaphini by the single claw of the tarsus and the large terminal segment of the maxillary palpus. This genus is conspicuously characterized by the antenna which is irregularly segmented in length, the third segment of maxillary * Contribution from the Entomological Laboratory, Faculty of Agriculture, Kyushu University, Fukuoka (Ser. 4, No. 6).

Study on the cestodes in Theragra chalcrogamma

This study was performed to investigate the intestinal parasites (especially cestoda) in the guts of Theragra chalcogramma in Korea. The cestode larvae collected were morphologically observed and measured, and at the same time, microscopical study was done with the section slides of the cestode larvae. They were identified on the basis of the descriptions by Schmidt and Yamaguti. The results obtained in this study are as follows: The cestode larvae were identified as Khawia sinesis, Eulacistorhynchus chiloscyllius, Tentacularia coryphaenea, Pseudonybelinia odontacantha and Nybelinia lingualis. These are new species reported in Korea. The characteristics of Khawia sinesis are its scolex lacking loculi and broad, flat and fimbriate shape. Its neck is not separated from the body but a little constricted. Eulacistorhynchus chiloscyllius is characterized by fairly long and acraspedote scolex. The bulbs are long; retractor muscles are attached to bases of the bulbs. The two bothridia are oval or round in shape and lacking posterior notch. The tentacles are long and poeciloacanthus; double chainette present. Tentacularia coryphaenea is characterized by its long craspedote and subcylindrical scolex. The bothridia are separated, without free borders and spinous. The tentacles are short, slender, armed with solid hooks in spirals, similar except the base of tentacle. The tentacle sheaths are not twisted. The bulbs are ellipsoidal. Pseudonybelinia odontacantha is characterized by its craspedote scolex. The tentacles are inserted near anterior margin of bothridia and armed with hooks in spirals ascending left to right. The hooks are similar, throughout tentacle, with feeble curve and provided with a tooth-like protuberance on the ventral side. The bulbs are three times longer than its width. The posterior margins of bothridia have a pair of eversible ciliated pits; or fossettes. Nybelinia lingualis is characterized by its short and craspedote scolex. The bothridia are separated, with free boarders. The tentacles are cylindrical, armed with solid and similar hooks in quincunxes.

The Structure and Function of the Infrared Receptors of Snakes

Publisher Summary This chapter discusses the structure and function of the infrared receptors of snakes. The pit vipers (Serpentes, Crotalinae) possess in the loreal region of the face a pair of pits that function as infrared receptors. Inside each pit, there is a sensory membrane heavily innervated by branches of the trigeminal nerve. The receptors contained in the membrane are masses of nude nerve branchlets surrounding several Schwann cells at the tip of numerous non-myelinated nerve fibers. These terminal nerve masses lie just under the outer epithelium of the sensory membrane and face in the direction of incoming infrared radiation. In response to infrared stimulation, generator, and action potentials have been recorded from the sensory membrane, action potentials from the peripheral nerves, and both action and evoked potentials from the tectum opticum of the brain. The peripheral nerves show spontaneous firing that increases in response to infrared stimulation and decreases or disappears in response to a cold stimulus. Central neurons show similar firing patterns, but with faster adaptation and great sensitivity to movement. The receptive field of central neurons is about 50–60 degrees in diameter. On the surface of the tectum, there is topic organization of the receptive fields similar to the retinotopic organization of the visual system. The pits function as receptors supplementary to the visual system in situations where vision is hampered, as in the dark.