Flagellar Segments Research Articles

Pentacentrus rectangulus sp. nov., the twelfth Pentacentrus species recorded in China (Orthoptera: Gryllidae; Pentacentrinae)

Pentacentrus rectangulus sp. nov. is the twelfth Pentacentrus species we have found in China. This new species has a uniformly colored head (without longitudinal yellow stripe on the occiput, and the color of the scape and peduncle segments is the same as that of the first three flagellar segments), and significantly curved ectoparamere. It has a similar coloration (coloration of the forewings and hind feet) to that of both Pentacentrus bituberus Liu & Shi, 2011 and Pentacentrus medogensis Zong, Qiu & Liu, 2017, but the morphology of the male genitalia differs markedly (the ventral inner margin of the epiphallus of the new has tufts of bristles, which is not present in either P. bituberus or P. medogensis). Here, we describe and illustrate the new species, and we also provide a key to the Chinese species of the genus.

Electron Microscopic and Morphometric Analysis of Wistar Rat Sperm

The aim of the study is to image and morphologically examine epididymal sperm in Wistar rats with scanning electron microscopy (SEM). The material of the study was epididymal sperm taken from three Wistar Rats. Routine fixation was performed on the obtained epididymal sperm using 2.5% glutaraldehyde solution. Morphometric measurements of sperm were carried out using scanning electron microscopy. The study focused on examining various regions of the sperm, including the head, midpiece, and the remainder of the flagellar segment. Measurements were taken into account in semen that preserved its integrity in different fields. Measurements of these regions were made with the ImageJ program. As a result of the measurements, it was determined that the average head length of rat semen was 7.821 ± 0.844 μm, the average total flagellum length was 168.549 ± 9.19 μm and the average flagellum/head ratio was 21.550 and the flagellum was quite long. It was observed that the measurements of the rat sperm used in the study were consistent with the measurements of other rat sperm. When the studies were examined, it was concluded that rat sperm has an extremely long flagellum compared to its body size. The morphological differences of the sperms revealed will be a guide for experimental studies.

A new freshwater amphipod (Amphipoda, Gammaridae) from the Fakıllı Cave, Düzce Türkiye: Gammarus kunti sp. nov.

Aquatic species (such as fish, amphipods, isopods, hirudineans etc.) adapted to environmental conditions can live in caves connected to groundwater. The species of Niphargus and Gammarus are the most commonly encountered amphipods in caves. Türkiye is very rich in terms of karst areas and is home to more than 2000 known caves. Fakıllı Cave, located in Düzce Province in the Western Anatolian Region, has a length of 1071 m. A new amphipod species belonging to the Gammarus genus has been identified from the cave and named as Gammarus kuntisp. nov. Some of the characteristic features of the newly-identified species can be listed as “Medium-large size; smooth body, well-developed and reniform eyes; non-prolonged extremities; antennal gland cone is straight and long; second antenna with setose peduncular and flagellar segments; medial palmar spine present; posterior margin of pereopod 3 densely setose; anterior margins of pereopods 6 and 7 armed with spines only; epimeral plates not pointed”. Although the mentioned features are generally seen in epigean species, the members of this species were sampled from the dark zone of the Fakıllı Cave. The partial sequences of the COI (573 bp) and 28S (914 bp) genes of the newly-described species, Gammarus kuntisp. nov., were generated. The pairwise genetic distances between the new species, Gammarus kunti sp. nov. and other species ranged from a minimum of 16.23% (G. tumaf) to a maximum of 28.27% (G. roeselii) for the COI gene and a minimum of 0.88% (G. tumaf) to a maximum of 6.81% (G. balcanicus) for the 28S gene. Phylogenies generated by the NJ and ML methods, based on the combined data, assigned the new species as an independent lineage with high support values. In addition, the ASAP method identified the new species as a single MOTU independent of other species. G. tumaf and G. baysali are the sister taxa of G. kuntisp. nov. Detailed descriptions and drawings of the extremities of the male holotype and the female allotype are given and the morphology of the newly-identified species is compared with its relatives.

Morphological Characterization of the Antennal Sensilla of the Legume Pod Borer, Maruca vitrata (Fabricius) (Lepidoptera: Crambidae).

Maruca vitrata (Fabricius) is an important lepidopteran pest of legumes in the tropics and subtropics. Here, we studied the ultrastructural organization of its antennal sense organs using scanning electron microscopy. The antennae of both sexes of M. vitrata were filiform with the number of flagellar segments varying from 72 to 84. Nine major morphological types of sensilla were observed on male and female antennae: sensilla trichodea (ST), sensilla basiconica (SB), sensilla auricillica (SA), sensilla chaetica (SCh), sensilla coeloconica (SCoe), sensilla cylindrica (SCy), sensilla squamiformia (SSq), sensilla styloconica (SSt), and Böhm sensilla (BS). Three of these sensilla types (SB, SSq, and BS) are newly reported for M. vitrata. Morphological observations revealed that four types are multiporous (ST, SB, SA, and SCoe), two types are uniporous (SCh and SCy), and three types are aporous (SSq, SSt, and BS). The average length of male ST was longer than that of the female. Sensilla cylindrica were observed only on male antennae, indicating sexual dimorphism. This study aims to provide some basic evidence for further studies on the mechanism of insect-plant chemical communication and future semiochemical-based management strategies of the major legume pest M. vitrata.

A new freshwater amphipod (Amphipoda, Gammaridae), Gammarus tumaf sp. nov. from the Gökgöl Cave, Türkiye

A new amphipod species belonging to the genus Gammarus is described from the Gökgöl Cave, Zonguldak Province, Türkiye. The newly-identified species is relatively small (13 mm) and is a member of the Gammarus pulex-group by the presence of numerous long setae along the posterior margins of pereopods 3 and 4. The specimens were sampled from a shallow pond located in the dark zone (about 1 km inside the entrance) of the cave. Minute eyes, setose (both peduncle and flagellar segments) second antenna, slightly swollen flagellar segments of the second antenna, setose pereopods 3 and 4 and relatively short endopod/exopod ratio of the third uropod are the character combination of the newly-identified species in addition to lacking body pigmentation. The molecular phylogeny, based on the concatenated dataset (28S+COI, 1495 bp) indicated that the new species was resolved from the other Gammarus species by high bootstrap (NJ: 100, ML: 100). In addition to Gammarus tumafsp. nov., mtDNA COI and nuclear DNA 28S gene data of Gammarus baysaliÖzbek et al., 2013 were recorded for the first time. The newly-identified species was well-differentiated from the genetically closest species, G. baysali, with genetic distance of 12.22% and 0.55% for the COI and 28S genes, respectively. Detailed descriptions and drawings of the extremities of the holotype male were given and the morphology of the newly-identified species is compared with its relatives.

Antennal sensory structures of Phenacoccus solenopsis (Hemiptera: Pseudococcidae)

BackgroundThe cotton mealybug Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) is one of the most devastating sap-sucking pests of cultivated plants. The success of P. solenopsis is attributable to its ecological resilience and insecticide resistance, making its control extremely difficult and expensive. Thus, alternative safe approaches are needed to prevent the pest population from reaching the economic threshold. One of these novel approaches is based on the fact that chemical communication via the olfactory system drives critical behaviors required for the survival and development of the species. This knowledge can be useful for controlling insect pests using traps based on semiochemicals. The antennae of insects are an invaluable model for studying the fundamentals of odor perception. Several efforts have been made to investigate the histological and ultrastructural organization of the olfactory organs, such as the antennae and maxillary palps, in many insect species. However, studies on the antennal sensory structures of Phenacoccus species are lacking. Furthermore, although enormous progress has been made in understanding the antennal structures of many mealybug species, the olfactory sensilla in the antennae of P. solenopsis have not yet been described. In this study, we describe, for the first time, the morphology and distribution of the antennal sensilla in male and female P. solenopsis using scanning electron microscopy.ResultsOur results revealed that the entire antennae length and the number of flagellar segments were different between the sexes. Eight morphological types of sensilla were identified on male antennae: trichoid sensilla, chaetic sensilla (three subtypes), basiconic sensilla (two subtypes), and campaniform sensilla (two subtypes). Six morphological types of sensilla were found on female antennae. Sensilla chaetica of subtype 2 and campaniform sensilla of subtype 1 were distributed only on male antennae, suggesting that these sensilla are involved in the recognition of female sex pheromones. The subtype 1 of sensilla chaetica was significantly more abundant on female antennae than on male ones, while subtype 3 was only located on the terminal flagellar segment of the antenna in both sexes.ConclusionsThis study provides insightful information for future electrophysiological and behavioral studies on chemical communication in insects, particularly the cotton mealybug, P. solenopsis that could help in developing new strategies for controlling this economically important insect species.

Deformation of appendages, antennal segments and sensilla of aphid (Aphis craccivora Koch) treated with Tagetes minuta oil: a scanning electron microscopy study

The effect of Tagetes minuta oil on the morphology of Aphis craccivora is reported in the scanning electron microscopy (SEM). Results showed that, flagellar segments of antenna treated with T. minuta showed filamentous and knotted without losing the setae after 96 h of treatment. The sensilla (Type I and II) showed remarkable deformation, reduction in the length and width. Morphometric measurements also helped to identify the deformed sensilla on cuticle and antenna. Type I and antennal sensilla reduced its length by 30% and type II sensilla by 42%. The breadth of type I and II sensilla also reduced by 35%.

Validating Morphometrics with DNA Barcoding to Reliably Separate Three Cryptic Species of Bombus Cresson (Hymenoptera: Apidae).

Simple SummaryEvidence of bumble bee population declines has led to an increase in conservation efforts to protect these important pollinators. However, effective conservation requires accurate species identification. We provide quantitative methods to accurately identify three cryptic species of bumble bees using morphometric measurements of the cheek length and width, and antennal segments. We validated the accuracy of our methods with DNA analysis. We predicted that these methods would reliably identify both the queens and worker bees of Bombus vagans and B. sandersoni. We expanded these methods to include an uncommon form of Bombus perplexus with all light hair on its thorax, rather than the more common light on top and dark below, that can mistakenly be identified as B. vagans or B. sandersoni. Although the species we consider here, Bombus vagans, B. sandersoni and B. perplexus, are not currently listed as species of concern in North America, there is uncertainty of their population status, some of which is due to difficulty in species identification, which we have resolved. Recent history informs us that some bumble bee species experience rapid declines within a few decades. Our methods to correctly identify these cryptic species is key to monitoring their status and population trends.Despite their large size and striking markings, the identification of bumble bees (Bombus spp.) is surprisingly difficult. This is particularly true for three North American sympatric species in the subgenus Pyrobombus that are often misidentified: B. sandersoni Franklin, B. vagans Smith B. perplexus Cresson. Traditionally, the identification of these cryptic species was based on observations of differences in hair coloration and pattern and qualitative comparisons of morphological characters including malar length. Unfortunately, these characteristics do not reliably separate these species. We present quantitative morphometric methods to separate these species based on the malar length to width ratio (MRL) and the ratios of the malar length to flagellar segments 1 (MR1) and 3 (MR3) for queens and workers, and validated our determinations based on DNA barcoding. All three measurements discriminated queens of B. sandersoni and B. vagans with 100% accuracy. For workers, we achieved 99% accuracy by combining both MR1 and MR3 measurements, and 100% accuracy differentiating workers using MRL. Moreover, measurements were highly repeatable within and among both experienced and inexperienced observers. Our results, validated by genetic evidence, demonstrate that malar measurements provide accurate identifications of B. vagans and B. sandersoni. There was considerable overlap in the measurements between B. perplexus and B. sandersoni. However, these species can usually be reliably separated by combining malar ratio measurements with other morphological features like hair color. The ability to identify bumble bees is key to monitoring the status and trends of their populations, and the methods we present here advance these efforts.

The Luciolinae of S. E. Asia and the Australopacific region: a revisionary checklist (Coleoptera: Lampyridae) including description of three new genera and 13 new species.

The Luciolinae of S. E. Asia and the Australopacific region: a revisionary checklist (Coleoptera: Lampyridae) including description of three new genera and 13 new species.

Documentation and validation of chemosensory structures in antennae of Spodoptera litura (Fabricius) through Scanning Electron Microscope (SEM)

The studies with SEM clearly depicted that the antenna of female was longer than male antenna. Five types of sensilla namely trichodea, chaetica, styloconica, coeloconica and auricillica, and scales were observed on the flagellum of both sexes. Sensilla trichodea were distributed randomly on all segments and were the most frequent type. Six sensilla chaetica were observed on each flagellar segment in both sexes, except in the apical segment. A sensillum styloconicum was always found at the upper-middle region of each flagellar subsegment. This sensillum had a smooth petiole and a conic extremity with one to three apical structures. Sensilla coeloconica were situated from middle to the distal portion of segment. Sensilla auricillica were found among the scales and had the typical shape of rabbit’s ear. Sensilla squamiformia were present on dorsal part of the antenna among scales. They were shorter and finer than scales and were embedded in a socket and point distally. Sensilla basiconica were smaller and least abundant of all sensilla.

Peynirlikönü Mağarası (EGMA Mağarası)’ndan bir diğer yeni Amphipod türü: Gammarus egmao sp. nov. (Crustacea: Amphipoda)

Another new amphipod species, Gammarus egmao sp. nov., from Peynirlikönü Cave [Evren Günay Mehmet Ali Özel (EGMA) Cave] was identified. The specimens of the new species were sampled from 350 m inside of the cave entrance. This is the second species identified from the cave in addition to Gammarus ustaoglui Özbek and Güloğlu, 2005. The newly identified species has the following characteristic features: a) small eyes, b) 2- segmented accessory flagellum of antenna II, c) aesthetascs on the flagellar segments of antenna I, d) reduced armaments in distal part of palp of maxilla I e) short inner ramus of uropod III and reduced setation on margins of rami of uropod III. A detailed description of holotype female and illustrations of the appendages were presented. Additionally, differences from the related species were discussed.

Comparative analysis of mammalian sperm ultrastructure reveals relationships between sperm morphology, mitochondrial functions and motility

BackgroundSperm morphology mainly refers to the shape of the head, the length of the flagellar segments, including the midpiece, principal piece and end piece, and the size of the accessory structures, including axonemes, outer dense fibers (ODFs), mitochondrial sheath (MS) and fibrous sheath (FS). Across species, there is considerable diversity in morphology. An established theory posits that the length of the sperm flagellum, especially the length of the midpiece, is a critical factor influencing sperm metabolism and velocity. However, our understanding of the relationships between sperm ultrastructures and the sperm flagellar length is incomplete.MethodsThe morphologies of sperm from 10 mammalian species, human, mouse, rat, dog, rabbit, goat, pig, bull, guinea pig and golden hamster, were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). According to the SEM and TME images, the length of sperm heads and flagellar segments, the cross-sectional areas of the accessory structures and flagella and the width of sperm heads were measured using Image J software. The variation tendencies (referred to as slope) of the accessory structures along flagella were calculated by the linear regression method. Mitochondrial functions were measured using commercial kits. The velocities of sperm were measured using CASA software.ResultsThe three-dimensional morphologies of sperm from 10 species and the slopes of internal accessory structures along flagella were obtained. The width of the axoneme tapered slightly from the base to the tip of the sperm flagellum, and slopes of the axonemes correlated negatively with the variability in flagellar length across species. Additionally, the cross-sectional areas of the ODFs and/or the MS were positively correlated with the lengths of the midpiece, principal piece, and total flagellum, as well as with sperm velocities. Mitochondrial volumes were positively correlated with ATP content and sperm swimming velocities.ConclusionsOur results not only show the relationship between sperm internal structures, flagellar length and sperm physiology but also provide sizes of mitochondria and ODFs as new targets with which to study the regulation of sperm length and velocity.

Surface Ultrastructure of Antenna and Distribution of Sensilla in the Leptogenys chinensis (Mayr) (Fabricus) (Formicidae: Hymenoptera)

Ants have well developed pair of antenna with sensory system used in chemical communication for social lives. The antennae comprise of two parts scape and funiculus. Funinculus contain single segmented pedicel and ten segmented flagellum. The surface micro-morphology of the antennal sensilla of Leptogenys chinensis worker shows presence of various types of sensilla viz. sensilla trichodea, sensilla trichodea curvata, sensilla basiconica, sensilla coeloconica, sensilla chaetica, sensilla coelocapitular. Sensilla trichodea is distributed on all parts of antenna. Sensilla trichodea curvata type III is typically present on flagellar segments only. Sensilla basiconica with arrowhead present on scape ball is slightly different than the sensilla basiconica with rounded head present on flagellar tip. Sensilla coelocapitular is observed only on the flagellar tip. On the joint of scape ball and pedicilar shaft three types of sensilla trichodea are present on the ball ridge while, sensilla basiconica distributed on dorso-lateral margin of ball. KEYWORDS: Ant, Leptogenys, antenna, sensilla, SEM

Comparison of sensory structures on the antenna of different species of Philopotamidae (Insecta: Trichoptera)

Structure and distribution of sensilla were studied in sixteen species of the caddisfly family Philopotamidae. Their antennae bear numerous curved trichoid and pseudoplacoid sensilla and fewer coronal, styloconic and chaetoid sensilla on the flagellar segments. The most numerous pseudoplacoid sensilla have non-specific localization. The curved trichoid sensilla form clusters ventrally on each antennal segment. Sensilla belonging to coronal, styloconic and chaetoid types have specific positions. Long grooved trichoid sensilla are located nonspecifically in all the studied species. The average number of sensilla per segment decreases from the proximal to distal part of the flagellum. Scapus and pedicellum are devoid of most types of sensilla, however, they bear the Böhm bristles and long trichoid sensilla. A positive correlation between antenna dimensions and its cuticular structures is found.

The antennae of damselfly larvae

The larval antennal sensilla of two Zygoptera species, Calopteryx haemorroidalis (Calopterygidae) and Ischnura elegans (Coenagrionidae) are investigated with SEM and TEM. These two species have different antennae (geniculate, setaceous) and live in different environments (lotic, lentic waters). Notwithstanding this, similarities in the kind and distribution of sensilla are outlined: in both species the majority of sensilla types is located on the apical portion of the antenna, namely a composed coeloconic sensillum (possible chemoreceptor), two other coeloconic sensilla (possible thermo-hygroreceptors) and an apical seta (direct contact mechanoreceptor). Other mechanoreceptors, such as filiform hairs sensitive to movements of the surrounding medium or bristles positioned to sense the movements of the flagellar segments, are present on the antenna. Similarities in the antennal sensilla types and distribution are observed also with other dragonfly species, such as Onychogomphus forcipatus and Libellula depressa. A peculiar structure with an internal organization similar to that of a gland is observed in the apical antenna of C. haemorroidalis and I. elegans and it is present also in O. forcipatus and L. depressa. The possible function of this structure is at the moment unknown but deserves further investigations owing to its widespread presence in Odonata larvae.

Description of the first juvenile stage of Dilocarcinus septemdentatus (Herbst, 1783) (Crustacea, Decapoda, Trichodactylidae)

Abstract A total of 38 freshwater brachyuran species occur in Brazil, of which 79% are distributed in the northern region. However, for only two species of freshwater crabs are descriptions available for their juveniles. The importance of these studies lies in understanding of life-cycle aspects as well the potential elucidation of phylogenetic relationships within the group because the characters are usually solely based on adult specimens. The morphology of the first juvenile stage of the Dilocarcinus septemdentatus (Herbst, 1783) is described and illustrated for the first time based on specimens hatched by an ovigerous female collected in the northeastern region of the Brazilian Amazon. Juveniles of Dilocarcinus pagei Stimpson, 1861 and D. septemdentatus have one flagellar segment on the exopod of the first maxilliped while the only described juvenile of an unidentified species of Trichodactylus Latreille, 1828 has two. Dilocarcinus septemdentatus differs from other congeneric species mainly in the number of setae on the antennae and number of segments of the mandibular palp. Variations in the number of segments and aesthetascs enable the comparison between the juveniles of D. septemdentatus with those of other Brachyuran species previously studied and suggest possible adaptations to freshwater environments.

Structure and postembryonic development of the intersegmental nodules in the non-muscular joints of the antennae in Rhodnius prolixus

The antennae of Insecta consist of two basal segments and the distal annulated flagellum lacking intrinsic muscles. Non-muscular joints are important to preserve the flexibility and structure of the long heteropteran antennae which bear an intersegmental nodule on each non-muscular joint. Little is known about their properties or function. Here we characterize the structure and postembryonic development of the non-muscular joints of Rhodnius prolixus antennae. Using Scanning Electron Microscopy, we tracked the changes in shape and size of both intersegmental nodules during the course of the hemimetabolous insect life cycle. Using Atomic Force Microscopy, we established a qualitative correlation between the topography of the surface and the rigidity of the joint between pedicel and flagellum. Our results confirmed the presence of two sub-articulations on each non-muscular joint. Also, the two intersegmental nodules have different origins: the one between the two flagellar segments (intraflagelloid) is a sclerite already present from the early nymph, while the nodule between pedicel and flagellum (prebasiflagellite) originates by gradual separation of the proximal end of the basiflagellum during postembryonic development. Various changes occur in the non-muscular joints and segments of the antenna during the life cycle of R. prolixus.

Antennal sensilla of phytophagous and predatory pentatomids (Hemiptera: Pentatomidae): a comparative study of four genera

Antennal sensilla of four genera of Pentatomidae (Hemiptera: Heteroptera) belonging to two subfamilies viz., Pentatominae and Asopinae were examined using scanning electron microscopy. The representatives selected from the subfamily Pentatominae (phytophagous)—Dolycoris indicus (Stål) and Plautia crossota (Dallas), and from the subfamily Asopinae (predatory)—Perillus bioculatus (Fabricius) and Eocanthecona furcellata (Wolff). They were studied in order to morphologically differentiate the sensilla present on the antennae. This study indicated the presence of six types of sensilla, most of which were found on the flagellar segments rather than on the scape or pedicel. Sensilla campaniformia were recorded on the flagellar segments as well as the scape and pedicel. Phytophagous species (D. indicus and P. crossota) showed a higher number of sensilla trichodea, basiconica and chaetica whereas sensilla coeloconica were restricted to the predatory species studied (E. furcellata and P. bioculatus). These differences may be related to their evolutionary history. The presence of multiporous chemo-sensilla as basiconic sensilla type and sensilla placoidea reflect the ability of the antennae to perceive chemical stimuli. A relatively higher abundance of mechanoreceptors could be considered as potential detectors for various mechanical functions and these appeared to be correlated with the genus and type of feeding but not with the sex of the studied species.

A new genus for Entophilus mirabiledictu Markham & Dworschak, 2005 (Crustacea: Isopoda: Cryptoniscoidea: Entophilidae) with remarks on morphological support for epicaridean superfamilies based on larval characters.

A detailed reexamination of male and female Entophilus mirabiledictu Markham & Dworschak, 2005 (an endoparasite of callianassid shrimp), resulted in recognition of seven female and five male characters that separate the species from its sole congener, E. omnitectus Richardson, 1903 (an endoparasite of munidid squat lobsters). These characters show that the two species are so different as to warrant E. mirabiledictu being placed in its own genus within the Entophilidae. Additionally, a review of the morphological features of entophilid cryptoniscus larvae led to the finding that the number of flagellar segments on the second antenna offers morphological support for a recent molecular phylogeny of epicaridean taxa that rearranged the component families within the two recognised superfamilies. This work highlights the power of using larval characters in testing hypotheses on the evolutionary relationships of epicaridean taxa.

The antenna of a burrowing dragonfly larva, Onychogomphus forcipatus (Anisoptera, Gomphidae)

The larva of the dragonfly Onychogomphus forcipatus (Anisoptera, Gomphidae) has a burrowing lifestyle and antennae composed of four short and broad segments (scape, pedicel and a two-segmented flagellum). The present ultrastructural investigation revealed that different sensilla and one gland are located on the antenna. There is a great diversity of mechanoreceptors of different kinds. In particular club-shaped sensilla, sensilla chaetica, and tree-like sensilla show the typical structure of bristles, the most common type of mechanoreceptors, usually responding to direct touch, while numerous long thin thorny trichoid sensilla show a morphology recalling the structure of filiform hair mechanoreceptors. The latter ones are presumably important in larval Odonata for current detection and rheotactic orientation, especially in a burrowing species. On the smooth apical cuticle of the second flagellar segment, three structures are visible: (1) a small ellipsoidal pit hosting a convoluted peg, the morphology of which resembles that of a typical chemoreceptor (even if pores are lacking), (2) a couple of small pits (not investigated under TEM), and (3) one wide depression with spherical structures, the internal morphology of which lets us assume that it is a gland with unknown function. This is the first report of an antennal gland in palaeopteran insects.