A new Upper Carboniferous stem‐orthopteran (Insecta) from Ningxia (China)

Abstract During the Upper Carboniferous, orthopteran insects (grasshoppers, katydids, and crickets) were represented by numerous species distantly related to crown‐orthopterans, such as lobeattid and cnemidolestodean insects. The panorthopterans, including total‐orthopterans and their closest relatives, are represented by comparatively rarer species in localities of this period. Here we describe Heterologus duyiwuer sp. nov., an infrequent panorthopteran from the Late Carboniferous locality of Xiaheyan Village (Zhongwei City, Ningxia Hui Autonomous Region, China). The only available specimen is composed of an isolated forewing exhibiting a combination of character states previously unknown, in particular the lack of posterior radius (RP) / anterior Media (MA) connection, late branchings of the media (M) and anterior cubitus (CuA), and a branched posterior branch of the posterior cubitus (CuPb). Based on its unusual branching pattern, the composite stem resulting from the fusion of CuA and CuPaα (second anterior branch of CuP) is assumed to be composed of a branched CuA and a simple CuPaα.     

Comparative morphological assessment and phylogenetic significance of the wing base articulation in Psylloidea (Insecta,Hemiptera, Sternorrhyncha)

The wing articulation sclerites, as well as wing base environment, of phylogenetically distant Psylloidea taxa were examined by optical and electron microscopy in order to estimate the phylogenetic significance of observed morphological patterns. The basiradial bridge is strongly developed and links the fused humeral plate, basisubcostale, basiradiale and second axillary sclerite to the fused veins R + M + Cu. The proximal median plate has a vertical orientation, which may have a role in moving the wing forward and backward. The weak sclerotization posteriad of the second axillary sclerite and anteriad to the third axillary sclerite facilitates the backward movement of the wing. The horizontal hinge (= basal hinge), the vertical hinge and the torsional hinge are the most important fold- and flexion-lines for the mobility of the wing, whereas humeral folds and the anterior axillary fold-line play a minor role. The basalare presents two horns or processes that are autapomorphic traits for the superfamily Psylloidea. The monophyly of Psylloidea is also supported by the absence of the subalare, of the median notal wing process and of the anterior arm of the third axillary sclerite (lacking articulation with second axillary sclerite). Major interspecific variations are observed in tegula, first axillary sclerite and basalare shape and size. The second distal median plate is absent in Homotoma ficus (Homotomidae) and Glycaspis brimblecombei (Spondyliaspidinae), whereas it is present in Calophya schini (Calophyidae) and Psylla buxi (Psyllinae/Arytaininae); the presence of this sclerite could be a synapomorphy linking Calophyidae and the “psyllid assemblage”.     

Secondary retinae of a primitive jumping spider,Yaginumanis (Arachnida,Araneida, Salticidae)

Summary Retinae of the secondary eyes of a primitive salticid spider, Yaginumanis sexdentatus (Yaginuma 1967) are described at the ultrastructural level. The structures of the anterior lateral, posterior lateral and posterior median eyes are identical. Receptor somata lie in the retinal cups. Each receptor bearing twin rhabdomeres is ensheated by (i) much-divided processes of non-pigmented glial cells whose somata lie distally in the retinal cups; and (ii) four processes of pigmented glial cells whose somata lie basally, below the receptive segments. Pigment granules in the latter are concentrated in the basal retina, and are not present at the level of the rhabdoms. The present findings support the placement of Yaginumanis in a newly erected Subfamily Spartaeinae by Wanless (1984), because of the likelihood of homology in the fine structural organisation of the secondary retinae of this genus and of the genus Portia.     

Comparative ultrastructure of the epidermal ciliary rootlets and associated structures in species of the Nemertodermatida and Acoela (Plathelminthes)

 The fine morphology of epidermal ciliary structures in four species of the Nemertodermatida and four species of the Acoela was studied, with emphasis on Meara stichopi (Nemertodermatida). The cilium of M. stichopi has a distal shelf and is proximally separated from the basal body by a cup-shaped structure. The bottom of the cup consists of a bilayered dense plate, or basal plate. The basal body consists of peripheral microtubule doublets continuous with those of the cilium. In the upper part of the basal body, the doublets are set at an angle and are anchored to the enclosing cell membrane by Y-shaped structures. The lower part of the basal body tapers eventually. The striated main rootlet arises on the anterior face of the basal body, initially like a flattened strap, and continues along the basal body shaped as a tube which further down becomes solid. The hour-glass-shaped posterior rootlet arises on the posterior face of the basal body. Contrary to the main rootlet, the striations in the proximal part of the posterior rootlet run parallel to the microtubule doublets of the basal body. A pair of microtubule bundles lead from the posterior rootlet to the two main rootlets in the hind ciliary row, and follow these to their lower tip. In the other species of the Nemertodermatida studied, the structure of the ciliary basal body and the ciliary rootlets is similar to that of M. stichopi. Structural differences in the species of the Acoela are that the lowermost end of the basal body is narrow and bent forwards, the proximal part of the main rootlet is trough-shaped, the main rootlet is accompanied by a pair of lateral rootlets and the posterior rootlet with associated microtubule bundles is thin. The epidermal ciliary structures in species of the Nemertodermatida and Acoela have a number of shared characters which are unique within the Plathelminthes. However, almost all of these characters are found in Xenoturbella bocki (Xenoturbellida), and some even in species of other ”phyla” of the ”lower” Metazoa. Hence, these characters cannot be considered apomorphic for the Acoelomorpha. A character seemingly present only in species of the Nemertodermatida and Acoela is the bilayered dense plate. This feature might represent an autapomorphic character state for the Acoelomorpha. Accepted: 7 March 1997     

A new genus and species of brown lacewing from Venezuela (Neuroptera: Hemerobiidae), with comments on the evolution of the hemerobiid forewing radial vein

Abstract. Biramus lunatus gen.n., sp.n. is described from Venezuela. This species is of special phylogenetic interest as it is the sister-group of the subfamily Hemerobiinae ( sensu Oswald, 1993), which previously contained four genera ( Hemerobiella, Hemerobius, Nesobiella and Wesmaelius ) and approximately 200 of the c. 550 world hemerobiid species. The conformation of the forewing radius in Biramus is especially interesting and provides a test case for distinguishing parallel evolution among forewing radial vein states within the Hemerobiidae.     

On the phylogenetic position of the palaeopteran Syntonopteroidea (Insecta: Ephemeroptera), with a new species from the Upper Carboniferous of England

A new syntonopterid, Anglolithoneura magnifica gen. et sp. n., is described from a siderite concretion (nodule) from the Late Carboniferous (Langsettian) of Lancashire County (UK). The new genus is diagnosed on hind wing venation and compared with other syntonopterid genera. The new species is the first syntonopterid formally described from the Late Carboniferous of Europe. The systematic positions of other potential Syntonopteroidea (Miracopteron mirabile, Bojophlebia prokopi, and specimens described in 1985 by J. Kukalová-Peck from Obora in the Czech Republic) are reconsidered. Wing venation synapomorphies are proposed for the Syntonopteroidea (sensu novo), and for a potential clade ((Ephemeroptera+Syntonopteroidea)+Odonatoptera) separated from the Palaeodictyopterida. The close relations of the new species with Lithoneura lameerei Carpenter, 1938 from Mazon Creek (Illinois, USA) provide additional support for a Euramerican connection during the Late Carboniferous.     

Evidence for Carboniferous origin of the order Mantodea (Insecta: Dictyoptera) gained from forewing morphology

Homologies of the forewing venation pattern of the order Mantodea (Insecta: Dictyoptera) consistent with the accepted insect wing venation groundplan are proposed. A comparative morphological analysis was carried out based on a broad taxonomic sample of extant taxa. Besides macromorphological aspects, focus is given to the pattern of the tracheal system as a basis for establishing primary homologies. All extant praying mantids exhibit a composite stem composed of the posterior radius (RP) and the media (M) and most praying mantids exhibit a fusion of the anterior branch of RP + M with the anterior radius (RA). The wing venation of the species ?Mesoptilus dolloi, previously assigned to the polyphyletic fossil assemblage ‘Protorthoptera’, is re‐interpreted in the light of the new homology statement. Our interpretation suggests that it is a putative stem‐Mantodea, as are some other ‘protorthopterous’ taxa. This hypothesis implies that the total‐group Mantodea arose as soon as the Late Carboniferous, i.e. about 175 million years earlier than previously estimated. This analysis contributes to the view that most of the Late Carboniferous ‘Protorthoptera’ are stem‐representatives of the major polyneopteran clades (e.g. cockroaches, grasshoppers and crickets, rock‐crawlers), suggesting a survivorship of several main Pterygota lineages at the end‐Permian extinction event higher than previously expected. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 156 , 79–113.     

Three‐dimensional organization of flagellar basal apparatus in Ectocarpus gametes

The flagellar basal apparatus of the brown alga Ectocarpus siliculosus was re‐investigated in details using transmission electron microscopy and electron tomography. As a result, three‐dimensional structures with spatial arrangement of bands and microtubular flagellar rootlets were observed. Fibrous structures linking the anterior flagellar basal body to the major anterior rootlet (R3) or the bypassing rootlet was newly discovered in this study. A direct attachment from the minor anterior rootlet (R4) to the anterior and posterior basal bodies was also discovered, as were attachments from the minor posterior rootlet (R1) to the deltoid striated band and from the major posterior rootlet (R2) to the posterior fibrous band. The microtubular flagellar rootlets were connected to the bands and to the anterior or posterior basal body. These bands may have a role in maintaining the spatial arrangement of the anterior and posterior flagellar basal bodies and the microtubular flagellar rootlets. A numbering system of the basal body triplets was established by tracing axonemal doublets in the serial sections. From these observations, the precise position of two flagellar basal bodies, bands, and flagellar rootlets was determined.     

Three new species of <Emphasis Type="Italic">Hatschekia</Emphasis> Poche, 1902 (Copepoda: Siphonostomatoida: Hatschekiidae) parasitic on <Emphasis Type="Italic">Abalistes filamentosus</Emphasis> (Pisces: Tetraodontiformes: Balistidae) from off Okinawa,Japan

Three new species of the copepod genus Hatschekia Poche, 1902, H. lima n. sp., H. cylindrus n. sp. and H. sunaoi n. sp., are described from the gill filaments of a triggerfish, Abalistes filamentosus Matsuura & Yoshino, caught off the Ryukyu Islands, Okinawa, Japan. These new species share an unusual morphological character, i.e. four stout posterior spines on the intercoxal sclerites of legs 1 and 2. H. lima n. sp. differs from its congeners in having a robust inner lobe on the maxillule and leg 3 with a swollen basal lobe. H. cylindrus n. sp. is distinguishable from its congeners by having a cephalothorax fused to the trunk and a double-semicircular chitinous frame. H. sunaoi n. sp. is characterised by leg 3 with a swollen basal lobe and an oval cephalothorax.     

Updating the Trachelocercids (Ciliophora, Karyorelictea). I. A Detailed Description of the Infraciliature of Trachelolophos gigas N. G., N. Sp. and T. filum (Dragesco & Dragesco-Kernéis, 1986) N. Comb

ABSTRACT. Trachelolophos gigas n. g., n. sp. and T. filum (Dragesco & Dragesco-Kernéis, 1986) n. comb. (basionym: Tracheloraphis filum) were discovered in the mesopsammon of the French Atlantic coast at Roscoff. Their morphology and infraciliature were studied in live and protargol impregnated specimens. The new genus, Trachelolophos, belongs to the family Trachelocercidae and is unique in having a conspicuous ciliary tuft, which is very likely a highly modified brosse, in the oral cavity. The two species investigated have a very similar infraciliature, differing only in morphometric characteristics and in the nuclear configuration. The entire somatic and oral infraciliature consists of dikinetids which have both basal bodies ciliated or only the anterior or posterior ones, depending on the region of the cell. The right side is densely and uniformly ciliated. Its kineties extend onto the left side to the glabrous stripe, where an anterior and posterior secant system are formed, reducing the number of kineties in the narrowed neck and tail region. The left side bears a narrow glabrous stripe bordered by slightly irregularly arranged dikinetids having rather stiff cilia (bristles), possibly forming an uninterrupted, prolate ellipsoidal (bristle) kinety as indicated by their ciliation. The bristle kinety commences subapically at the right margin of the glabrous stripe, extends posteriorly, then anteriorly at the left, to end up at the right margin again. The dikinetids of the right posterior portion of the bristle kinety have the posterior basal bodies ciliated, whereas the anterior basal bodies are ciliated in its left and right anterior portion. The ends of the bristle kinety meet distinctly subapically at the right margin of the glabrous stripe, as indicated by the diametrically opposed ciliation of the dikinetids. The anterior region (head) of the cell bears a distinct circumoral kinety composed of very regularly arranged dikinetids, associated with nematodesmata forming an oral basket together with the nematodesmal bundles originating from the oralized somatic dikinetids at the anterior end of the somatic kineties. The systematics of trachelocercid ciliates are briefly reviewed and discussed.     

Spectral sensitivities of jumping spider eyes

Summary Spectral sensitivities of the anterior lateral, posterior lateral and anterior median eyes of the jumping spider,Menemerus confusus Boes. et Str. have been studied by recording electroretinograms (ERGs) and receptor potentials. The anterior and posterior lateral eyes have a single type of visual cell with a maximum spectral sensitivity at about 535–540 nm. The anterior median eye has four types of visual cells with maximum sensitivities at about 360, 480–500, 520–540 and 580 nm, respectively. The ERGs recorded from the optic nerve side (posterior part of the retina) were affected greatly by long wave chromatic light and those on the corneal side (anterior part of the retina) by short wave chromatic light, suggesting that each receptor layer contains a different photopigment.     

Respiratory significance of the thoracic and abdominal morphology of the three aquatic bugs Ambrysus,Notonecta and Hesperocorixa (Insecta,Heteroptera)

The spiracular chambers of the three anterior pairs of spiracles are described, and their relationships with the air stores on the body are discussed. Morphological variations in the spiracular chambers of Ambrysus, Notonecta, and Hesperocorixa appear to be correlated with the manner in which these insects obtain atmospheric and dissolved oxygen.

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Explanation of Figures AB Abdominal segment - AC Antecosta - AF Flap on second abdominal segment - AM Alar membrane - AP Abdominal projection of second abdominal segment - AT Air trough of metathoracic spiracular chamber - AX Humeral axillary sclerite - CL Clavus of forewing - CM Coxal membrane - CO Corium of forewing - CP Metacoxal process - CS Claval suture of forewing - CX Coxa - D Wing-anchoring depression on costal margin of forewing - DVM Dorsoventral muscle of first abdominal segment - E Embolium of forewing - EM Epimeron - ES Episternum - FE Femur - FL Posterior flap on costal margin of forewing - FW Forewing - G Gap between forewing and body - OR Groove on abdominal projection - H Horizontal ridge or sulcus - HA Hairs on precoxal bridge HD Head - HL Laterosternal hairs - HW Hindwing - L Laterosternite of abdomen - LH Lateral hairs of ventral abdominal air channel - LM Epirneral lobe - LMO Opening into epimeral lobe - LN Notal lobe - LS Episternal lobe - MI-II Membrane between prothorax and mesothorax - MB Membrane of forewing - MH Medial hairs of ventral abdominal air channel - MP Process for dorsoventral muscle of first abdominal segment - N Notum - P Pleural ridge or sulcus - PB Postalar bridge - PN Postnotum - PP Postalar projection of postalar bridge - R Ridge on metathoracic episternum - RS Rounded swelling on costal margin of forewing - S Spiracle - SA Subalar air store - SC Spiracular chamber - SO Scolopophorous sense organ - ST Sternum - TA Thoracico-abdominal sclerite - TAL Thoracico-abdominal lobe of thoracico-abdominal sclerite - TAM Functional (not morphological) thoracico-abdominal membrane - TAO Opening into thoracico-abdominal lobe - TR Trochanter - V Vertical ridge or sulcus - VP Vertical plate of thoracico-abdominal sclerite - WA Wing-anchoring process of mesothoracic epimeron - WF Wing-anchoring flap on costal margin of forewing - WH Hairs on emboliar margin of forewing - WM Costal margin of forewing - WR Ridge on inner surface of forewing - XC Axillary cord of forewing - 2 or 3 PH Second or third phragma - II–III Boundary between mesothorax and metathorax     

Geometric and traditional morphometrics for the assessment of character state identity: multivariate statistical analyses of character variation in the genus Arrenurus (Acari,Hydrachnidia, Arrenuridae)

Geometric and traditional morphometric approaches are tested to describe and reveal taxonomic characters and character states in variation of shape and size of idiosoma morphology in the Arrenuridae. Patterns of variation of idiosoma and glandularia features of males from 11 Mexican species of Arrenurus (Megaluracarus) and two species of subgenus Dadayella were explored with five landmark configurations and three sets of interlandmark distances. Separate principal component analyses (PCA) and canonical variate analyses (CVA) were performed for each data set. The eight multivariate analyses of variance among 13 a priori groups (species) detected significantly different morphometric variants, which were interpreted as different taxonomic character states. Patterns of character state similarity among species were examined with unweighted‐pair grouping method using averages (UPGMA) cluster analyses on Mahalanobis distances. Analyses of five landmark configurations revealed important taxonomical variation in the anterior idiosoma outline (10 character states), the outline of the posterior region or cauda (13 states), the distribution of postocularia, and the second and third pairs of dorsoglandularia (nine states), the fourth pair of dorsoglandularia (three states), and ventroglandularia on the posterior side of idiosoma (nine character states). Multivariate analyses of three sets of distance measurements also resulted in the detection of potential taxonomic characters related to idiosoma size (12 character states), postocularia and dorsoglandularia (13 states), and ventroglandularia (nine character states). Morphometric analyses of distances and shapes provide a formal basis for the interpretation of taxonomic characters, and for the discovery of character states. These characters should be investigated further in a wider sample of species for the phylogenetic systematics of these water mites. In the meantime, idiosoma regions and structures were tested for congruence in a phylogenetic analysis, and were proposed as homologous among the species sampled.     

Edmund Fredric Warburg; 1908–1966

Abstract

Ultrastructural analyses of mid-stage spermatids of Hypnum jutlandicum and H. mammillatum reveal a maximally structured blepharoplast closely similar in most respects to the other moss taxa previously investigated. The multilayered structure is four-layered and the dimorphic basal bodies highy staggered. The latter are inserted into the gamete in a slightly staggered subapical position. Both are longer than those reported for the majority of mosses and hepatics. Like other true mosses, the posterior basal body diverges from the longitudinal axis of the spermatid and is associated with a solitary microtubule which is equally divergent from the main body of the spline. In contrast to previous reports on other mosses, the stray microtubule of Hypnum is here interpreted as remaining separate from the spline, i.e., it does not converge posteriorly with the body of the spline.

The lamellar strip of Hypnum is roughly oblong in outline with an acute anterior tip which extends beyond the spline microtubules both anteriorly and on the righthand side. The posterior margin of the lamellar strip rapidly tapers from right to left. Like most mosses, the lamellar strip is approximately the same length as the anterior basal body and terminates at the level of the anterior basal body transition zone. In hepatics, in contrast, the lamellar strip subtends the posterior basal body over most of its length.     

Glossomastix chrysoplasta n. gen., n. sp. (Pinguiophyceae), a new coccoidal, colony-forming golden alga from southern Australia

Glossomastix chrysoplasta gen. et sp. nov. is described from cultures isolated from sandstone rubble, Sorrento Back Beach, Mornington Peninsula, Victoria, Australia. The alga forms wall‐less, coccoidal vegetative cells that congregate in mucilaginous colonies and reproduce by successive bipartition. Plastids have girdle lamellae and partially embedded pyrenoids that are traversed by cytoplasmic channels. Zoospores are uniflagellate and swim poorly; a narrow lingulate pseudopod provides their primary form of motion. The single flagellum, which lacks hairs, a flagellar swelling, and autofluorescence, is the equivalent of the posterior flagellum in other golden algae. The anterior flagellum is absent; the basal body with which it would normally be associated is blind. The flagellar apparatus has two basal bodies, three microtubular roots, and a rhizoplast. The posterior (elder) basal body has a transitional helix that is proximal to the basal plate. Glossomastix chrysoplasta, placed in the Pinguiophyceae on the basis of molecular sequence and biochemical data, shares some ultrastructural features with other members of the class, especially Polypodochrysis teissieri, which has similar zoospores, but it also differs from other pinguiophytes in many respects. Glossomastix chrysoplasta is the pinguiophyte with, on average, the largest cells (exclusive of external materials), and it is the only one with a colonial habit.     

Microscopic anatomy and fine structure of the skeleton-heart-kidney complex in <Emphasis Type="Italic">Saccoglossus mereschkowskii</Emphasis> (Hemichordata,Enteropneusta): 1. Stalk skeleton

This is the first paper of the series devoted to the microscopic anatomy and fine structure of the skeleton-heart-kidney complex in the acorn worm Saccoglossus mereschkowskii Wagner 1885. The skeleton of S. mereschkowskii consists of the unpaired anterior plate (lamina imparis) and two posterior horns (corni). The anterior plate bears a pair of lateral wings (alae laterales), the midventral keel (carina ventralis), the central fossa (fossa centralis) with the bordering ridge (crista circumflexa fossae centralis), two symmetrical supporting saucers (subiculi), and the conical rostrum (rostrum). The skeleton is an accretion (overgrowth) of the basal lamina between the epidermis and the endodermal epithelium of the buccal diverticulum (in the anterior part) and between the endodermal epithelia of the buccal diverticulum and the gut (in the posterior part) and consists of collagen fibers, mostly longitudinal. In all representatives of the Enteropneusta studied to date, the skeleton is a wishbone-like structure with the unpaired anterior plate and paired posterior horns, but its components widely vary in shape between species. In the family Harrimaniidae, the horns are long, and the anterior plate is rod-shaped. In the Ptychoderidae, the horns are short, and the anterior plate is rectangular. In the Spengelidae, the skeleton has an intermediate shape.     

Guyiling jianboni gen. et sp.n., an antlion‐like lacewing,illuminating homologies and transformations in Neuroptera wing venation

A new genus and species of antlion‐like fossil lacewing, Guyiling jianboni gen. et sp.n. (Insecta: Neuroptera) are described based on a single specimen from the Yixian Formation (Liaoning Province, China; Early Cretaceous). The new taxon exhibits derived traits such as distally dilated antennae and well‐developed anterior Banksian line (known in Myrmeleontidae), but also genuine plesiomorphies (at the level of Myrmeleontiformia), such as the divergence of a distinct CuA1 stem from MP2 + CuA1 (forewing), and a basal origin of MA (diverging from RP + MA; both wing pairs). This combination is unique among the ‘Palaeoleontidae’, a group better considered as a paraphyletic assemblage of various stem‐Myrmeleontiformia. The wing morphology of the new species is considered in the light of a survey of wing venation topological homologies (and implied transformations) among several Neuroptera families. The survey includes a revision of the holotype of Leptolingia jurassica Ren (Grammolingiidae; Jiulongshan Formation, Daohugou locality, Inner Mongolia Autonomous Region, China; middle Jurassic). The forewing morphology of Guyiling jianboni gen. et sp.n. demonstrates that the fusion of MP2 with CuA, and the differentiation of CuA into two distinct main stems (namely CuA1 and CuA2) are traits shared with Myrmeleontidae and Ascalaphidae (and possibly Nemopteridae). However, the survey also demonstrates that a fusion of MP2 with CuA occurred repeatedly among Neuropterida, although by means of various modalities (namely translocation vs regular fusion). The ‘pectinate fusion’ of CuA(1) with MP2 [i.e. CuA1 has no distinct stem and emits successive branches from MP2 + CuA(1) partim] is a further step in this fusion, and occurred repeatedly as well (at least in the hind wings of Osmylidae and Nymphidae, and both fore‐ and hindwings of a sub‐group of Myrmeleontiformia including Myrmeleontidae and Ascalaphidae, and possibly Nemopteridae). It is anticipated that the current contribution will constitute useful background information for further studies, focusing on particular transformation cases, ideally including a documentation of intraspecific variation.     

Spermiogenesis and spermatozoon ultrastructure of the dilepidid cestode Molluscotaenia crassiscolex (von Linstow, 1890), an intestinal parasite of the common shrew Sorex araneus

Marigo, A.M., Bâ, C.T. and Miquel, J. 2011. Spermiogenesis and spermatozoon ultrastructure of the dilepidid cestode Molluscotaenia crassiscolex (von Linstow, 1890), an intestinal parasite of the common shrew Sorex araneus. —Acta Zoologica (Stockholm) 92 : 116–125. Spermiogenesis in Molluscotaenia crassiscolex begins with the formation of a differentiation zone containing two centrioles. One of the centrioles develops a flagellum directly into the cytoplasmic extension. The nucleus elongates and later migrates along the spermatid body. During advanced stages of spermiogenesis, a periaxonemal sheath appears in the spermatid. Spermiogenesis finishes with the appearance of a single helicoidal crested body at the base of the spermatid and, finally, the narrowing of the ring of arched membranes causes the detachment of the fully formed spermatozoon. The mature spermatozoon of M. crassiscolex exhibits a partially detached crested body in the anterior region of the spermatozoon, one axoneme, twisted cortical microtubules, a periaxonemal sheath, and a spiralled nucleus. The anterior spermatozoon extremity is characterized by the presence of an electron‐dense apical cone and a single spiralled crested body, which is attached to the sperm cell in the anterior and posterior areas of region I, whereas in the middle area it is partially detached from the cell. This crested body is described for the first time in cestodes. The posterior extremity of the male gamete exhibits only the disorganizing axoneme. Results are discussed and compared particularly with the available ultrastructural data on dilepidids sensu lato.     

Anatomy,histology, and histochemistry of the olfactory organ of the Korean shuttles mudskipper Periophthalmus modestus

The Korean shuttles mudskipper Periophthalmus modestus has paired olfactory organs on its snout, consisting of anterior and posterior nostrils, a single olfactory canal with sensory and nonsensory epithelia, and a single accessory nasal sac. Its sensory epithelium consists of numerous islets forming a pseudostratified layer and contains various cells: olfactory receptor neurons, supporting cells, basal cells, lymphatic cells (LCs), and axon bundles. The sensory epithelium is a stratified squamous layer comprising stratified epithelial cells, mucous cells (MCs) with glycogen, flattened cells (FCs), LCs, and unidentified cells. Specific structures are as follows: (a) a tubular anterior nostril projecting outward, (b) a slit posterior nostril, (c) an elongated olfactory canal, (d) an ethmoidal accessory nasal sac, (e) axon bundles found only in the basal layer of the sensory epithelium, (f) FCs only at the top of the nonsensory epithelium, and (g) glycogen-containing MCs. Such structures seem to be unique in that they have not been observed in most teleost fishes spending their whole life in water.