Posterior Ocelli Research Articles

The first fossil Parascleroderma (Hymenoptera: Bethylidae): a new species in mid-Miocene Zhangpu amber

The recently discovered amber biota from Zhangpu, China, offers a unique window into the tropical ecosystem of an Asian rainforest during the Mid-Miocene Climatic Optimum (MMCO). Here, the first flat wasp (Bethylidae) from this deposit is documented: Parascleroderma palaeosinica n. sp. is described and figured from a single male, and is the first fossil Parascleroderma known to date. The new extinct species is characterized by its minute size, the pedicel longer than the flagellomeres, the posterior ocelli inserted much posteriad on head, the notauli not impressed on anterior third of anteromesoscutum, and the hypopygium simple, with posterior margin slightly incurved medially. Parascleroderma is a cosmopolitan genus within the Pristocerinae and it is therefore not surprising to find its record in the Zhangpu biota, simultaneously with the northern expansion of the southeastern Asian tropical forest during the MMCO.

A new species of Chiridurothrips Okajima from Miocene amber of the Dominican Republic (Thysanoptera: Phlaeothripidae).

The thysanopteran genus Chiridurothrips Okajima is known from a single extant species, C. hisakoae Okajima, collected in Japan (ThripsWiki 2019). Occurring on dead leaves and branches of evergreen trees in the subtropical Ryukyu Islands, this species remains known from only five females (Okajima 1981, 2006; also pers. comm. 2018). Within Phlaeothripidae, Chiridurothrips is associated with the tribe Plectrothripini. Species of this sub-group feed on fungal hyphae or the break-down products of fungal attack on decaying plant material (Mound Ng 2018). They are found mainly under the bark of trees or on dead branches, and they do not seem to inhabit leaf-litter (Okajima 1981). At present, Plectrothripini comprises 60 extant species in 13 genera, with no fossils recorded. Of these species 32 are placed in the genus Plectrothrips Hood, ten in Streptothrips Priesner, and six in Chirothripoides Bagnall, whereas both Menothrips Hood and Mastigothrips Priesner each include only two species. The remaining eight species are all placed in separate monobasic genera (ThripsWiki 2019). Concerning this strongly asymmetric classification, Mound and Ng (2018) suggest that Plectrothripini might be particularly old, with the large number of monobasic genera each representing a relict lineage. An alternative possibility, however, might be an unusual instability in the genes controlling morphogenetic processes, and thus resulting in striking autapomorphies on which each one of these genera is diagnosed (Mound Ng 2018). Species associated with Plectrothripini share the following character states (Okajima 1981; Mound Tree 2017): antennae 8-segmented, segment II with the campaniform sensillum situated in the basal half, III-IV with stout sense cones, VIII slender with narrow base; head with posterior ocelli close to compound eyes; pronotum commonly with sclerotized plate eroded or reduced, prosternal basantra week or absent; legs with fore tarsal tooth large; mid and hind tibiae commonly with apical spur-like setae; macropterae with fore wings parallel-sided, usually with duplicated cilia; pelta broad at base, abdominal tergite II eroded laterally; abdominal sternites often with reticulate glandular areas. Regarding the fore wings, it seems worth mentioning that in some members of Plectrothripini the subbasal wing vein is reduced and thus the three subbasal wing setae are lacking (see Plectrothrips tenuis Okajima, Chiridurothrips [c.f. fig. 2], Chirothripoides, Lonchothrips Hood; Bhatti 1998; Okajima 1981). This short vein that is present in (almost all) other macropterous Phlaeothripidae has been interpreted as a plesiomorphic feature that resulted from the reduction of a former well-developed longitudinal first vein of ancestral Tubulifera, the Rohrthripidae (Ulitzka 2018, 2019).

Shared and distinct mechanisms of atonal regulation in Drosophila ocelli and compound eyes

The fruit fly Drosophila melanogaster has two types of external visual organs, a pair of compound eyes and a group of three ocelli. At the time of neurogenesis, the proneural transcription factor Atonal mediates the transition from progenitor cells to differentiating photoreceptor neurons in both organs. In the developing compound eye, atonal (ato) expression is directly induced by transcriptional regulators that confer retinal identity, the Retinal Determination (RD) factors. Little is known, however, about control of ato transcription in the ocelli. Here we show that a 2kb genomic DNA fragment contains distinct and common regulatory elements necessary for ato induction in compound eyes and ocelli. The three binding sites that mediate direct regulation by the RD factors Sine oculis and Eyeless in the compound eye are also required in the ocelli. However, in the latter, these sites mediate control by Sine oculis and the other Pax6 factor of Drosophila, Twin of eyeless, which can bind the Pax6 sites in vitro. Moreover, the three sites are differentially utilized in the ocelli: all three are similarly essential for atonal induction in the posterior ocelli, but show considerable redundancy in the anterior ocellus. Strikingly, this difference parallels the distinct control of ato transcription in the posterior and anterior progenitors of the developing compound eyes. From a comparative perspective, our findings suggest that the ocelli of arthropods may have originated through spatial partitioning from the dorsal edge of an ancestral compound eye.

The first micropterous species of the southern European genus Kakothrips(Thysanoptera: Thripidae).

The European genus Kakothrips Williams includes seven species (ThripsWiki 2015) that are known to be flower-living mainly on Fabaceae plants. The genus is recorded across Europe from Morocco to England, and eastwards to Syria and Iran (zur Strassen 2003). Only K. pisivorus (Westwood) is known from northern Europe, and this is the senior synonym of the type species K. robustus (Uzel) (Collins 2010). Closely related to Frankliniella, the species share with the members of that genus the character states of ctenidia present on tergite VIII anterolateral to the spiracles, and a complete row of setae on both longitudinal veins of the fore wing. Also, the pronotal anteromarginal and anteroangular setae are half as long as the posteroangular setae. The character states of the genus Kakothrips include: ocellar setae pair III arising between posterior ocelli; fore tarsus with an apical tooth, laterally; pronotal posterior margin without a pair of small setae between the major posteromarginal setae. In some of the species the males bear a pair of stout tubercles laterally on tergite VIII, and sternites III-VI or III-VII of males have a transverse pore plate. All the described species are known only from macropterae, and they are similar to each other in structure. A few distinguishing characters include colour of body, fore wings and antennal segments; the shape, length and position of the fore tarsal tooth; size of body, antennal segments, and major setae; and in males, shape of sternal pore plates, and length of setae on tergite IX.

Anteroposterior patterning of Drosophila ocelli requires an anti-repressor mechanism within the hh pathway mediated by the Six3 gene Optix.

In addition to compound eyes, most insects possess a set of three dorsal ocelli that develop at the vertices of a triangular cuticle patch, forming the ocellar complex. The wingless and hedgehog signaling pathways, together with the transcription factor encoded by orthodenticle, are known to play major roles in the specification and patterning of the ocellar complex. Specifically, hedgehog is responsible for the choice between ocellus and cuticle fates within the ocellar complex primordium. However, the interactions between signals and transcription factors known to date do not fully explain how this choice is controlled. We show that this binary choice depends on dynamic changes in the domains of hedgehog signaling. In this dynamics, the restricted expression of engrailed, a hedgehog signaling target, is key because it defines a domain within the complex where hedgehog transcription is maintained while the pathway activity is blocked. We further show that the Drosophila Six3, optix, is expressed in and required for the development of the anterior ocellus specifically, limiting the ocellar expression domain of en. This finding confirms previous genetic evidence that the spatial allocation of the primordia of anterior and posterior ocelli is differentially regulated, which may apply to the patterning of the insect head in general.

Three new species of the subfamily Microgastrinae (Hymenoptera: Braconidae) from Vietnam

Three new species of the subfamily Microgastrinae (Hymenoptera: Braconidae) from Vietnam

A Hh-driven gene network controls specification, pattern and size of the Drosophila simple eyes

During development, extracellular signaling molecules interact with intracellular gene networks to control the specification, pattern and size of organs. One such signaling molecule is Hedgehog (Hh). Hh is known to act as a morphogen, instructing different fates depending on the distance to its source. However, how Hh, when signaling across a cell field, impacts organ-specific transcriptional networks is still poorly understood. Here, we investigate this issue during the development of the Drosophila ocellar complex. The development of this sensory structure, which is composed of three simple eyes (or ocelli) located at the vertices of a triangular patch of cuticle on the dorsal head, depends on Hh signaling and on the definition of three domains: two areas of eya and so expression--the prospective anterior and posterior ocelli--and the intervening interocellar domain. Our results highlight the role of the homeodomain transcription factor engrailed (en) both as a target and as a transcriptional repressor of hh signaling in the prospective interocellar region. Furthermore, we identify a requirement for the Notch pathway in the establishment of en maintenance in a Hh-independent manner. Therefore, hh signals transiently during the specification of the interocellar domain, with en being required here for hh signaling attenuation. Computational analysis further suggests that this network design confers robustness to signaling noise and constrains phenotypic variation. In summary, using genetics and modeling we have expanded the ocellar gene network to explain how the interaction between the Hh gradient and this gene network results in the generation of stable mutually exclusive gene expression domains. In addition, we discuss some general implications our model may have in some Hh-driven gene networks.

Scirtothrips aurantii, Scirtothrips citri, Scirtothrips dorsalis

<i>Scirtothrips aurantii</i>, <i>Scirtothrips citri</i>, <i>Scirtothrips dorsalis</i>

Studies on Nearctic species of Leucopis (Diptera: Chamaemyiidae). II. New species

Fifteen new Nearctic species of Leucopis (Diptera, Chamaemyiidae) are described: L. canthogena sp. n., L. rotundogena sp. n., L. ankophalla sp. n., L. saliceti sp. n., L. schlingeri sp. n., L. velutinifrons sp. n., L. dislineata sp. n., L. philoisos sp. n., L. aglaia sp. n., L. charactophalla sp. n., L. askophalla sp. n., L. lotophila sp. n., L. shannoni sp. n., L. chillcotti sp. n., and L. hermanni sp. n.

Localization of a visual Gq protein in the photoreceptors of a polychaete, Perinereis brevicirris (Annelida).

Heterotrimeric GTP-binding proteins (G proteins) play an important role in phototransduction. The presence of G-protein subclasses has been reported in photoreceptive membranes, e.g., the Gi subgroup (transducin) in vertebrate rods, and the Gq subgroup in the eyes of the Arthropoda and the Mollusca. We examined the immunoreactivity and distribution of a Gq homologue in the cerebral ocelli of Perinereis brevicirris (Polychaeta, Annelida) using an anti-GqC antibody raised against a conserved sequence at the C-terminal of the alpha-subunit of Gq (Gq-alpha). The anti-GqC antibody labeled a 48-kDa band on the Western blot of proteins from the Perinereis ocelli. The anti-GtC antibody, which is raised against the C-terminal sequence of bovine transducin alpha-subunit (Gt-alpha), did not cross-react to the ocellar proteins of Perinereis. The rhabdomeric layers of the anterior and posterior ocelli were strongly labeled by anti-GqC on light-microscopic immunohistology. Immunoelectron microscopy showed that the Gq molecules were specifically localized in the photoreceptive membrane of the rhabdomeric microvilli. These results suggest that the Gq protein plays a role in the phototransduction of the Perinereis ocelli.

Ocellar system of the swallowtail butterfly larva: I. Structure of the lateral ocelli

The structure of the lateral ocelli in the larva of the swallowtail butterfly, Papilio xuthus, has been examined in this study. The larva possesses six ocelli on both sides of its head with cuticular lenses of the six ocelli oriented in different directions. Positioned beneath the lens is a crystalline cone consisting of three cone cells; the retinula consists of seven retinular cells. In all six ocelli the rhabdom is thin and columnar proximally, and is expanded distally into a flower-shaped configuration. However, two distinct rhabdomic patterns occur. In the four frontal ocelli, the distal rhabdom consists of three large rhabdomeres, while the proximal rhabdom is formed by four cells. In the two posterior ocelli, the distal rhabdom has a complicated pattern consisting of seven cells four distal, two peripheral, and one central), whereas the proximal rhabdom is formed by only the central cell. These results suggest that the distal cells may be highly sensitive, whereas the proximal cells in the frontal ocelli, and the central cell in the posterior ocelli with a narrow acceptance angle may be less sensitive. The two types of retinulae are ensheathed by corneagenous cells with different cytoplasmic inclusions. These results are discussed in relation to various visual functions known for lepidopteran larvae such as pattern recognition, movement detection, color discrimination, and polarized light detection.

Three new leeches (Piscicolidae) from marine shore fishes (Cottidae) in British waters

Two species of Malmiana (=Ottoniobdella) are recorded from Cottusbubalis on the Yorkshire coast. Malmiana bubali sp. n. has sixeyes, but no metameric markings or posterior ocelli. Malmiana yorki sp. n. has four eyes and 14 posterior ocelli. The body in both is somewhat flattened, but their other characters clearly place them in this genus, the history of which is reviewed.

On the Indo-Malayan Species of the Genus Microgaster (Hymenoptera, Braconidae)

♂. Black ; flagellum brownish red, hind legs from the femora to the claws blackish red ; scape, fore and middle legs, hind trochanters and hind trochantines, light testaceous red ; palpi almost white ; basal ventrites whitish ; stigma and wing veins brown.♂. Head rugose throughout, except that the occiput is rugoso-reticulate and that the vertex between the ocelli and the toruli is rugoso-striate ; face with indications of a median keel ; antennae moderately thick and strong ; basal joint of flagellum a little longer than twice its breadth, about 0·24 mm. long ; clypeus apparently emarginate, just about half as long as distance between facial depressions, which latter are nearer to the eyes than to the apex of the clypeus ; posterior ocelli nearer to the eyes than to each other. Thorax : mesonotum closely and strongly punctate, anteriorly almost rugose, as are also the mesopleurae except for a posterior median smooth and shining area ; mesopleural sulcus apparently smooth ; scutellum apparently rugose ; metanotum apparently not crenulate ; propodeon with an extremely short median longitudinal carina which, bifurcating at its apex, emits two strong carinae which, on each side, run transversely across the basal half of the propodeon and join a strong carina which in conjunction with a strong lateral longitudinal carina encircles the spiracles, as in M. kuchingensis ; remainder of the propodeon apparently rugose between broad reticulations, except outside the lateral keels, where it is only rugose.

New Thysanoptera from Florida: IV

Head: Length about 1/6 longer than wide, cheeks nearly straight, slightly converging posteriorly, postocular bristles dilated into a small head, rather shorter than the eyes. Eyes small, occupying about one-third the length of the head, rounded, not protuding, not.produced on the ventral surface. Posterior ocelli opposite the anterior one-third of the eyes. Antennae nearly twice as long as the head. Segments all short and thick; 2-6 about equal in length; 1 and base and inner border of 2 concolorous with the head; remainder of 2, and 3 yellowish brown; 4 darker; 5-8 dark brown. Mouth Cone rounded at the apex. Prothorax nearly as long as head and nearly twice as wide as long, a long and short bristle on each posterior angle and a conspicuous one in the middle of each side, all capitate. Pterothorax about as wide as prothorax. Wing membrane with a brown area at the extreme base, plainly narrowed in the middle. Fringing hairs sparse but long, no interlocated ones. Legs rather short, fore tibiae slightly enlarged, tarsi devoid of teeth. Abdomen long and slender, 4.5 times as long as broad, prominently banded with dark brown and orange, sparsely provided with bristles some of which are capitate and some pointed. Tube about half as long as the head. Described from a single ? taken from ironweed (Vernonia) at Gainesville Aug. 7, 1919. The species is remarkably close to H. bellus Hood and Williams in most characters but is longer (smaller in most measurements except the abdomen); the eyes are not produced on the ventral side; and the intermediate segments are shorter. merely writing about this subject thinking that i will be 18