Taxonomic Review of the Orders Mysida and Stygiomysida (Crustacea,Peracarida)

The order Mysida (2 families, 178 genera, 1132 species) contains species across a broad range of habitats, such as subterranean, fresh, brackish, coastal, and surface to deep-sea habitats. The Stygiomysida (2 families, 2 genera, 16 species), however, are found primarily in subterranean waters, but always in waters with a marine influence. The Mysida and Stygiomysida body is divided into three main regions: cephalon, thorax, and abdomen. They are shrimp-like in appearance, containing morphological features earlier referred to as defining a "caridoid facies". The shrimp-like morphology was to some extent diagnostic for the historic Decapod taxon Schizopoda, containing the Nebalia, Mysida, Lophogastrida, and Euphausiacea. In 1904 the concept of Schizopoda was abandoned, and the Mysidacea (Mysida and Lophogastrida) along with Cumacea, Amphipoda, Isopoda, and Tanaidacea were placed in a new taxon, the Peracarida. Later discoveries of groundwater mysids led to the establishment of Stygiomysida, but placement to either Lophogastrida or Mysida remained unclear. The presence of oostegites and absence of podobranchiae, coupled with non-statocyst bearing uropods have been used to classify the Stygiomysida as a primitive Mysida family, comparable to Petalophthalmidae. On the other hand, equally suggestive characters, but for a Lophogastrida affiliation, was suggested for the archaic foregut characters and again, non-statocyst bearing uropods. With the inclusion of DNA sequence data of ribosomal genes, sister group relationships between Stygiomysida, Lophogastrida, and Mictacea within the Peracarida are observed, which supports a classification of the Stygiomysida as a separate order removed from the Mysida.     

Comparative morphology of the external male genitalia in Lophogastrida, Stygiomysida, and Mysida (Crustacea, Eumalacostraca)

External organs associated with the male gonopore are described for 29 species covering for the first time all seven currently acknowledged, extant families of the orders Lophogastrida, Stygiomysida, and Mysida, and all ten subfamilies of the Mysidae (Mysida). The gonopores are located throughout on the structures of the coxa of the eighth thoracopods. The three orders are consistently differentiated based on their male genital characteristics. Species of the Stygiomysida genera Stygiomysis (Stygiomysidae) and Spelaeomysis (Lepidomysidae) share a closing apparatus formed by two laminar lobes flanking the genital orifice, an anterior setose lobe, and a posterior bare lobe; no tubular penes are developed. In contrast, the Lophogastrida are characterized by a bare, slot-like orifice without lobes; also, in this taxon, no tubular penes are developed. The gonopore is on the inner wall of the coxa without conspicuous elevation in the species of Eucopia (Eucopiidae) and Lophogaster (Lophogastridae) and on the top of an anvil-like elevation in Paralophogaster (Lophogastridae), or of a dome-shaped elevation in Gnathophausia and Neognathophausia (Gnathophausiidae). In all examined species of the Mysida, the gonopores show a closing apparatus formed by lobes; one or more of these lobes is setose in most species. Within the Mysida, the genus Hansenomysis (Petalophthalmidae) and most subfamilies of the Mysidae have well-developed paired penes with (sub) terminal orifice. Only Rhopalophthalmus (Rhopalophthalminae) lacks penes but has bilobate gonopores located without additional elevation at the inner distal corner of the strongly enlarged coxa of the eighth thoracopods; this coxa contains a large seminal vesicle. Within the variety of external male genitalia in the Eumalacostraca, the structures associated with the gonopores appear to be plesiomorphic in Lophogastrida. In the Mysida, they appear to be apomorphic and support the monophyly of this order with respect to the previously published, competing phylogenetic trees. This requires additional evidence in the case of the Stygiomysida.     

28S rDNA evolution in the Eumalacostraca and the phylogenetic position of krill

The Malacostraca are an ancient and morphologically diverse class of Crustacea. The phylogenetic position of one order within this class, the Euphausiacea ("krill," subclass Eumalacostraca) was investigated using 28S rDNA sequences from representatives of several malacostracan orders. Phylogenies for these sequences were estimated by maximum-likelihood and maximum-parsimony analysis. The results of these analyses produced a new scheme for evolution within the Eumalacostraca. The new phylogenies suggested that Euphausiacea are most closely related to the Mysida and not the Decapoda, as is generally thought. Furthermore, the Mysida were found not to be closely related to the Lophogastrida, which are often considered their sister taxon. These hypotheses were tested against the hypotheses of monophyly for the Eucarida, Mysidacea, and Peracarida and found to be significantly better on the basis of the 28S rDNA data.     

The circulatory system in Mysidacea--implications for the phylogenetic position of Lophogastrida and Mysida (Malacostraca, Crustacea)

The morphology of the circulatory organs in Mysida and Lophogastrida (traditionally combined as Mysidacea) is revisited investigating species so far unstudied. In addition to classical morphological methods, a newly developed combination of corrosion casting with micro computer tomography (MicroCT) and computer aided 3D reconstructions is used. Lophogastrida and Mysida show a highly developed arterial system. The tubular heart extends through the greater part of the thorax and is connected with the ventral vessel via an unpaired descending artery. It is suggested that a distinct ostia pattern supports the monophyly of Mysidacea. The cardiac artery system is more complex in Lophogastrida than in Mysida, consisting of up to 10 pairs of arteries that supply the viscera. In both taxa, an anterior and posterior aorta leads off the heart. In the anterior part of the cephalothorax the anterior aorta forms dilations into which muscles are internalized; these structures are called myoarterial formations. One of these myoarterial formations can also be found in all the other peracarid taxa but not in other Malacostraca.     

The foreguts of the primitive families of the Mysida (Crustacea, Peracarida): a transitional link between those of the Lophogastrida (Crustacea, Mysidacea) and the most evolved Mysida

De Jong-Moreau, L. and Casanova, J.-P. 2001. The foreguts of the primitive families of the Mysida (Crustacea, Peracarida): a transitional link between those of the Lophogastrida (Crustacea, Mysidacea) and the most evolved Mysida. — Acta Zoologica (Stockholm) 82 : 137–147
The morphology of the foregut, which is a good indicator of phylogenetic relationships, has been studied within the two suborders of the Mysidacea. Special attention has been focused on rare species belonging to the Lophogastrida and the three primitive families of the Mysida, i.e. Stygiomysidae, Lepidomysidae and Petalophthalmidae. It appears that the foregut of Gnathophausia gracilis (Lophogastrida) is the most primitive in the Mysidacea, and that in the Petalophthalmidae the foregut exhibits transitional stages between that of the Lophogastrida and of the evolved Mysidae. Moreover, in the four families of Mysida, ancestral characteristics of the foregut remain, thus strengthening the hypothesis of the unity of this order.     

Phylogenetic analysis of the Malacostraca (Crustacea)

The Malacostraca comprises about 28 000 species with a broad disparity in morphology, anatomy, embryology, behaviour and ecology. The phylogenetic relationships of the major taxa are still under debate. Is the Leptostraca the sister group of the remaining Malacostraca, or is this taxon more closely related to other Crustacea? Does the Stomatopoda or the Bathynellacea represent the most basal taxon within the remaining taxa? Is the Peracarida monophyletic or are some peracarid taxa more closely related to other ‘caridoid’ taxa? Is the Thermosbaenacea part of the Peracarida or its sister group, and how much support is there for a taxon Amphipoda + Isopoda? To answer these questions a phylogenetic analysis of the Malacostraca combining different phylogenetic approaches was undertaken. In a first step, the monophyly of the Malacostraca including the Leptostraca is shown using the ‘Hennigian approach’. A computer cladistic analysis of the Malacostraca was carried out with NONA and PEE ‐WEE , based on 93 characters from morphology, anatomy and embryology. Nineteen higher malacostracan taxa are included in our analysis. Taxa whose representatives are exclusively fossils were not included. The Leptostraca was used as an operational out‐group. The present analysis supports the basal position of the Stomatopoda. Syncarida and Peracarida (including Thermosbaenacea) are supported as monophyletic, the Eucarida is not. Instead a sister‐group relationship is suggested between Euphausiacea and Peracarida (including Thermosbaenacea), with the Syncarida as the sister group to both taxa. Certain embryonic characters are interpreted as support for the monophyly of the Peracarida (without Thermosbaenacea) because convergences or reversals of these characters seem implausible. Within the Peracarida, the Mysidacea (Lophogastrida + Mysida) represents the sister group to the remaining taxa. A sister‐group relationship between Amphipoda and Isopoda is not supported.     

Locomotory mechanisms in Antarctic pycnogonids

Patterns of walking, modes of joint movement, and individual limb diversity were analysed with the aid of ciné film of several living Antarctic pycnogonids, including the 8-legged Colossendeis australis, C. angusta, Pallenopsis patagonica , and Nymphon sp., the 10-legged Decolopoda australis , and the 12-legged Dodecolopoda mawsoni. Appendage musculature of several of these species and also of the 10-legged Pentapycnon charcoti and Pentanymphon antarcticurn was dissected. At least two distinct morphotypes were identified: a short-legged, crawling variety ( P. charcoti ); and the more typical long-legged, large bodied, walking forms. No gross differences in musculature of joints were noted in the species examined. All joints are, at least superficially, hinge joints. The coxa-body joint is largely immobile, the coxa 1-coxa 2 joint alone exhibits promotion-remotion and all other joints are flexion-extension joints. The 8-legged forms move in an imprecise manner, there being irregularity of leg raising and lowering and where legs touch down in relation to the body and to other legs. The 10- and 12-legged forms exhibit more precise patterns of metachronal leg movements. Although legs move in a basic promotion-remotion, extension-flexion mode, there is a certain degree of twisting of a leg as it is picked up, brought forward, and set down; models indicating how such joint movement occurs were constructed. The possibility that hydrostatic pressure is employed in extension is considered and is found to be remote. Lateral placement of legs, orientated in almost all directions in the horizontal plane of the trunk, achieves a versatility of movement similar to that in crabs. Comments on pycnogonid taxonomic affinities are offered.     

The disunity of "Mysidacea" (Crustacea)

New studies on malacostracan relationships have drawn attention to issues concerning monophyly of the order Mysidacea, manifested in recent crustacean classifications that treat the taxon as two separate orders, Lophogastrida and Mysida. We present molecular phylogenies of these orders based on complete sequences of nuclear small-subunit ribosomal DNA (18S rRNA), and morphological evidence is used to revise the classification of the order Mysida to better reflect evolutionary history. A secondary structure model for 18S rRNA was constructed and used to assign putative stem and loop regions to two groups of partitions for phylogenetic analyses. Phylogenies were estimated by maximum-likelihood, Bayesian inference, and maximum-parsimony. The analyses gave strong support for three independently derived lineages, represented by three monophyletic groups, Lophogastrida, Stygiomysida, and Mysida. The family Petalophthalmidae is considered as sister group to the family Mysidae, and Boreomysinae and Rhopalophthalminae are the most early derived of the Mysidae. The tribes contained in the current classification of the subfamily Mysinae are not well-supported by either molecular data or morphology.     

The crustacean heart ultrastructure and its bearing upon the position of the isopods in eumalacostracan phylogeny

The present paper discusses the use of myocardial ultrastructure, and its merits, in studies of crustacean phylogeny. It is argued that different modifications of the heart do not affect the membrane systems of the myofibers and that the membrane systems are independent of size and/or adaptation of the species. Finally, the phylogenetic implications of the membrane systems are considered. Using the myocardial membrane systems in addition to the cephalothorax (carapace), compound eyes, respiratory system and heart anatomy, a new phylogenetic arrangement of the larger eumalacostracan orders (Anaspidacea, Amphipoda, Cumacea, Decapoda, Euphausiacea, Isopoda, Mysidacea, Tanaidacea) is suggested. The isopods are regarded as a sister group to the other eumalacostracans.     

Dynamic and static control of the human knee joint in abduction-adduction

It is unclear whether humans can voluntarily control dynamic and static properties in knee abduction-adduction, which may be important in performing functional tasks and preventing injuries, whether the main load is about the abduction axis or not. A joint-driving device was used to perturb the knee in abduction-adduction at full knee extension under both passive (muscle relaxed) and active (muscle contracted in abduction or adduction) conditions. Dynamic control properties in knee abduction-adduction were characterized by joint stiffness, viscosity, and limb inertia, and quasi-static knee torque-angle relationship was characterized by knee abduction-adduction laxity and quasi-static stiffness (at a 20Nm moment). It was found that the subjects were capable of generating net abduction and adduction moment through differential co-contraction of muscles crossing the medial and lateral sides of the knee, which helped to reduce the abduction-adduction joint laxity (p< or =0.01) and increase stiffness (p<0.027) and viscous damping. Knee abduction laxity was significantly lower than adduction laxity (p=0.043) and the quasi-static abduction stiffness was significantly higher than adduction stiffness (p<0.001). The knee joint showed significantly higher stiffness and viscosity in abduction-adduction than their counterparts in knee flexion-extension at comparable levels of joint torque (p<0.05). Similar to dynamic flexion-extension properties, the system damping ratio remained constant over different levels of contraction, indicating simplified control tasks for the central nervous system; while the natural undamped frequency increased considerably with abduction-adduction muscle contraction, presumably making the knee a quicker system during strenuous tasks involving strong muscle contraction.     

Morphology and evolution of the ectethmoid-mandibular articulation in the meliphagidae (Aves)

The ectethmoid-mandibular articulation in Melithreptus and Manorina (Meliphagidae: Aves) consists of the dorsal mandibular process fitting into and abutting against the ventral ectethmoid fossa; it forms a brace for the mandible. This articulation in Melithreptus is a typical diarthrosis with long folded capsular walls. The mandible, thus, has two separate articulations, each with a different axis of rotation. No other genus of Meliphagidae (except Ptiloprora) or any other avian family possesses a similar feature. The jaw and tongue musculature of Melithreptus are described. The two muscles opening the jaws are well developed, while those closing the jaws are small. The tongue muscles show no special developments. A large maxillary gland, presumably muscus secreting, covers the ventral surface of the jaw muscles. Its duct opens into the oral cavity just behind the tip of the upper jaw. The frilled tip of the tongue rests against the duct opening. The ectethmoid-mandibular articulation braces the adducted mandible against dorsoposteriorly directed forces. The mandible can be held closed without a compression force exerted by the mandible on the quadrate, permitting the bird to raise its upper jaw with greater ease and less loss of force. The tongue can be protruded through the slight gap between the jaws, moving against the duct opening and thus be coated with mucus. Presumably, these birds capture insects with their sticky tongue. Hence, the ectethmoid-mandibular articulation is an adaptation for this feeding method; it evolved independently in three genera of the Meliphagidae. The ectethmoid-mandibular articulation demonstrates that a bone can have two articulations with different axes of rotation, that the two articular halves can separate widely, and that articular cartilages can be flat and remain in contact over a large area. Its function suggests that the basitemporal articulation of the mandible found in many other birds has a similar function. And it demonstrates that in the evolution of the mammalian dentary-squamosal articulation, the new hinge did not have to lie on the same rotational axis as the existing quadrate-articular hinge.     

Gimbals in the insect leg

We studied the common kinematic features of the coxa and trochanter in cursorial and raptorial legs, which are the short size of the podomers, predominantly monoaxial joints, and the approximate orthogonality of adjacent joint axes. The chain coxa-trochanter with its short elements and serial orthogonality of joint axes resembles the gimbals which combine versatility and tolerance to external perturbations. The geometry of legs was studied in 23 insect species of 12 orders. Insects with monoaxial joints were selected. The joint between the trochanter and the femur (TFJ) is defined either by two vestigial condyles or by a straight anterior hinge. Direction of the joint axes in the two basal podomers was assessed by 3D measurements or by goniometry in two planes. Length of the coxa is <15% (mostly <8%) of the total length of the cursorial leg, that of the trochanter <10%. Angles between the proximal and distal joint axes in the middle coxa range from 124 to 84 degrees (mean 97+/-14 degrees ), in the trochanter (in all legs studied) from 125 to 72 degrees (mean 90+/-13 degrees ). Vectors of the distal axis in the coxa are concentrated about the normal to the plane defined by the proximal axis and the midpoint between the distal condyles. These vectors in the trochanter lie at various angles to the normal; angles are correlated with the direction of the TFJ relative to the femur. Range of reduction about the TFJ is over 60 degrees in the foreleg of Ranatra linearis, Mantispa lobata and the hind leg in Carabus coriaceus (confirming observations of previous authors), 40-60 degrees in the foreleg of Vespa crabro and in the middle one in Ammophila campestris, 10-30 degrees in other studied specimens. The special role of the trochanter in autotomy and in active propulsion in some insect groups is discussed. The majority of insects possess small trochanters and slightly movable TFJs with the joint axis laying in the femur-tibia plane. We pose the hypothesis that the TFJ damps external forces, the vectors of which lie off the femur-tibia plane, the reductor muscle acting as a spring. Thus the TFJ contributes to dynamic stability of legged locomotion.     

Psammaspides williamsi gen.n., sp.n., ein Vertreter einer neuen Familie mesopsammaler Anaspidacea (Crustacea, Syncarida)

A new species of the order Anaspidacea, Psammaspides williamsi gen.n., sp.n., is described from Australia. It belongs to a family of its own, Psammaspididae fam.n. This family seems to bridge the gap between the Stygocarididae and the Anaspidacea. The new species was found in gravel along a stream in northern New South Wales extending the range of distribution of the Anaspidacea far beyond its known limits to the north. It is the first fully interstitial species within the Anaspidacea.

Zusammenfassung

Eine neue Art der Ordnung Anaspidacea, Psammaspides williamsi gen.n., sp.n. wird aus Australien beschrieben. Sie gehört zu einer neuen Familie, den Psammaspididae. Diese Familie scheint zwischen den Stygocarididae und den Anaspidacea zu vermitteln. Die neue Art wurde im Schotter eines Baches im nördlichen New South Wales entdeckt und dehnt das Verbreitungsareal der Anaspidacea weit über seine bisher bekannten Grenzen nach Norden aus. Es ist die erste echt mesopsammale Art innerhalb der Anaspidacea.     

Index finger position fluctuations reflect multi-muscle coordination

We hypothesized that movement fluctuations in the index finger reflect the integrated result of the coordination of multiple muscles because index finger movements are determined by the cooperation of multiple muscles spanning the metacarpophalangeal (MCP) joint. To evaluate this hypothesis, the aim of the present study was to examine the fluctuations of the index finger in abduction-adduction and extension-flexion directions during a position-holding task using two laser displacement sensors. Eleven healthy men maintained their index finger position while supporting a load at 5% of the maximal voluntary contraction force. To maintain the position of the index finger, displacement of the index finger in the abduction-adduction and extension-flexion directions was measured from a distance with two laser displacement sensors that were positioned to the lateral side of and above the index finger. The index finger movements fluctuated around the target position in not only the abduction-adduction direction but also the extension-flexion direction. The path length of finger displacement and the standard deviation of finger acceleration were significantly greater in the extension-flexion direction than in the abduction-adduction direction. These results suggest that the index finger movements quantified by two laser displacement sensors reflect the coordination of multiple muscles spanning the MCP joint.     

The functional anatomy of the hindlimb of some African Viverridae (Carnivora).

The functional anatomy of the hindlimb of 12 species of viverrids was studied with relation to locomotion. The animals were allocated to primary locomotor categories on the basis of their anatomy and locomotion. The climbing, arboreal walking category (Nandinia binotata) is characterized by a small sacroiliac articulation, the iliopsoas inserts onto a medially located lesser trochanter and the femoral condyles are not posteriorly placed. The hindfoot is plantigrade and its structure permits considerable movement. The pads are soft and the claws retractile. Representatives of the arboreal and terrestrial walking and jumping category (Genetta genetta, G. servalina, G. tigrina) have a plantigrade forefoot and digitigrade hindfoot. The lesser trochanter is more posteriorly placed than in the climbing category. A previously undescribed muscle, the caudofemoralis profundus extends from several anterior caudal vertebrae to the femur. The tibio-astragular joint restricts supination of the foot. There is little mediolateral movement in the digitidgrade foot. The claws are retractile. In the general terrestrial walking and scrambling group (Helogale parvula, Mungos mungo, Atilax paludinosus, Bdeogale crassicauda, Herpestes ichneumon, H. sanguineus) the animals have essentially similar hindlimbs except for size differences and modifications to the feet. Helogale and Mungos have large medial epicondyles on the humerus and large terminal phalanges. Bdeogale has a vestigial first metatarsal, while Atilax can splay its digits. In all species the distal phalanges are non-retractile. The trotting category (Civettictis civetta, Ichneumia albicauda) is characterized by longer epipodials and metapodials and a more proximal position of muscle bellies. Most of the adaptations minimize rotation, adduction and abduction of the leg and supination of the foot. The metatarsals are closely adjoined and the distal phalanx is stout and non-retractile. There appear to be two levels of locomotory adaptation. Major adaptations affect the whole appendicular skeleton and are used to assign animals to primary locomotor categories. Minor adaptations occur mainly in the foot and indicate the more specific habits of the animal.     

Internal and external morphology of the deutonymph of Caloglyphus boharti (Arachnida: Acari)

A band of flexible cuticle encircles the deutonymph, separating the dorsal and ventral plates. The coxae are large, flat and fused with one another to form most of the ventor. Individual coxal margins are redefined as sternites, epimerites or simply apodemes according to which margins fuse with which others. A given area of cuticle may have patches of dark or light cuticle not corresponding to particular structures or cuticular contours; this is a source of confusion to taxonomists. Each leg has a dicondylic coxal-trochantal (adduction-abduction) and trochantal-femoral (promotion-remotion) joint with opposing muscles. The three more distal monocondylic joints (flexion-extension) have only flexor muscles; extension is by increased haemolymph pressure. The five apodemes of the sucker plate provide rigidity; the four suckers attach by a flexible cuticular ring to a solid flange or socket in the sucker plate. The sucker muscles attach to the center of each sucker. The flat, external face of the sucker plate apodemes may complement sucker action by adhesion. Coxal discs and sucker plate discs are identical, contain birefringent cuticular elements, and are considered modified setae. Functional mouthparts and a pharynx are lacking, but a cheliceral anlage is present. The esophagus, midgut and caecae, and malpighian tubules are lumenless and the cells small. The hindgut has a lumen, larger cells and opens externally via the anus. Whereas the digestive tract is regressed, the reproductive system is yet incompletely developed. In older deutonymphs anlagen of ducts, accessory glands and gonads are discernible. The nature of the haemocoel and peritoneum remains nuclear. The central nerve mass is conspicuously large for the size of the deutonymph. The supraesophageal ganglion gives rise to the cheliceral nerves; all other nerves arise from the subesophageal ganglion. Most major nerves were traced to the effector organs. The muscles are divided into leg, dorso-ventral (derived from coxal muscles), dorsal, sucker, and anogenital muscles. The trochantal adductor muscles originate on an endosternite, which is supported by muscles running to the dorsal hysterosoma. The dorso-ventral and propodosomal retractor muscles affect haemolymph pressure. The massive sucker retractor muscles are unique to this instar. Anogenital muscles are not well developed.     

Fluid movement and joint capsule strains due to flexion in rabbit knees

Diarthrodial joints are freely moveable joints containing synovial fluid (SF) within a connective tissue joint capsule that allows for low-friction and low-wear articulation of the cartilaginous ends of long bones. Biomechanical cues from joint articulation regulate synoviocyte and cartilage biology via joint capsule strain, in turn altering the composition of SF. Joint flexion is clinically associated with pain in knees with arthritis and effusion, with the nociception possibly originating from joint capsule strain. The hypothesis of this study was that knee fluid volume distribution and joint capsule strain are altered with passive flexion in the rabbit model. The aims were to (a) determine the volume distribution of fluid in the joint at different total volumes and with flexion of rabbit knees ex vivo, (b) correlate the volume distribution for the ex vivo model to in vivo data, and (c) determine the strains at different locations in the joint capsule with flexion. During knee flexion, ～20% of anteriorly located joint fluid moved posteriorly, correlating well with the fluid motion observed in in vivo joints. Planar joint capsule principal strains were ～100% (tension) in the proximal-distal direction and ～-40% (shortening) in the circumferential direction, relative to the femur axis and 30° strain state. The joint capsule strains with flexion are consistent with the mechanics of the tendons and ligaments from which the capsule tissue is derived. The movement and mixing of SF volume with flexion determine the mechanical and biological fluid environment within the knee joint. Joint fluid movement and capsular strains affect synovial cell biology and likely modulate trans-synovial transport.     

Evidence for the presence of serotonin in Mysidacea (Crustacea,Peracarida) as revealed by fluorescence immunohistochemistry

In crustaceans, serotonin (5-HT) exerts a wide range of physiological actions on many tissues. However, 5-HT has not been detected to date in Mysidacea (Crustacea, Peracarida). We have investigated the presence of 5-HT in the brain and the eyestalks of two Mysida (Leptomysis lingvura, Hemimysis margalefi) and one Lophogastrida (Lophogaster typicus) species by using the immunohistofluorescence technique. 5-HT-like immunopositive areas exhibit a similar pattern in the three species. 5-HT-like immunostaining is present in the retinular photosensitive cells, except in the deep-living species L. typicus. 5-HT-like cell bodies and fibres are observed in the lamina ganglionaris and in the three medullae. In the sinus gland, only 5-HT-like endings are detected. In the eyestalks, 5-HT-like fibres detected in the optic tract link with the protocerebrum, in which 5-HT-like somata and their extensions are found. Some neurones are detected in the anterior median cell cluster, in the protocerebral bridge and in the central body. In the deutocerebrum, the paracentral lobes are connected by immunoreactive fibres that run along the deutocerebral commissure. The glomeruli of the olfactory lobes exhibit strong diffuse immunostaining. Beside and in the median part of the deutocerebrum, at least two large serotoninergic neurones project their axons into the olfactory lobe cell cluster. Immunoreactive fibres are also found in the antennular neuropiles. Our results demonstrate the presence of 5-HT-like cell bodies and fibres in Mysidacea. The distribution patterns of the 5-HT immunoreactivity found herein are compared with those of other peracarids and decapods.     

A joint coordinate system proposal for the study of the trapeziometacarpal joint kinematics

The International Society of Biomechanics (ISB) has recommended a standardisation for the motion reporting of almost all human joints. This study proposes an adaptation for the trapeziometacarpal joint. The definition of the segment coordinate system of both trapezium and first metacarpal is based on functional anatomy. The definition of the joint coordinate system (JCS) is guided by the two degrees of freedom of the joint, i.e. flexion-extension about a trapezium axis and abduction-adduction about a first metacarpal axis. The rotations obtained using three methods are compared on the same data: the fixed axes sequence proposed by Cooney et al., the mobile axes sequence proposed by the ISB and our alternative mobile axes sequence. The rotation amplitudes show a difference of 9 degrees in flexion-extension, 2 degrees in abduction-adduction and 13 degrees in internal-external rotation. This study emphasizes the importance of adapting the JCS to the functional anatomy of each particular joint.