Research Article |
Corresponding author: Barbara Franielczyk-Pietyra ( barbara.franielczyk-pietyra@us.edu.pl ) Academic editor: Roger Blackman
© 2018 Barbara Franielczyk-Pietyra, Łukasz Depa, Piotr Wegierek.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Franielczyk-Pietyra B, Depa Ł, Wegierek P (2018) Morphological and histological study of the forewing of Orthezia urticae (Linnaeus, 1758) (Hemiptera, Sternorrhyncha). ZooKeys 747: 101-114. https://doi.org/10.3897/zookeys.747.23950
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Wings of Orthezia urticae males were studied. Both ventral and dorsal surfaces of wings were examined under light and scanning electron microscopes. The structure regarded as vein cubitus anterior turned out to be a reinforcement element only. Two elements known as radius sector and media are almost transparent depressions in the wing membrane. Veins at the margin of the fold of the wing anal lobe were not confirmed. Studies indicated a row of sensilla cupola at the beginning of the subcostal ridge.
Cross sections of the wing membrane showed a two-layered membrane. The presence of two veins was confirmed in a common stem – subcostal and radius. The change of common stem shape was described. Neither tracheae nor nerves were observed. This is the second paper on cross-sections of wing within Sternorrhyncha.
Coccoids, cross-section, forewing, morphology, ultrastructure, wing veins
Infraorder Coccomorpha (Fallen 1814) comprises scale insects, also known as coccoids. They are sap-sucking hemipterans, divided into two main groups: more primitive archaeococcoids and “advanced” neococcoids (
The analysis of the O. urticae forewing was made in detail by
After
The first element, so-called Sc+R, is convex and composed of subcostal (Sc) and radial (R1) veins. Between the anterior wing edge and the subcostal ridge, there is a narrow field (1, Fig.
To verify the above interpretations of the wing venation, we present the reconstruction of the course and the inner structure of wing veins in Orthezia urticae (Linnaeus, 1758). We also suggest changes in wing venation nomenclature (Fig.
Recently, for the first time within Sternorrhyncha, cross-sections of wing were made for an aphid representative, Aphis fabae (Scopoli, 1763) (
Methods were the same as in the previous article (
Nomenclature of the veins is after
af anal fold;
alf fold of anal lobe;
als alar setae;
cs campaniform sensilla;
R radius;
R1 first branch of radius (RA in the interpretation of
“rs” (= Rs) radius sector (RP in the interpretation of
“ms” (= M) media;
mt marginal thickening;
“cua” (= CuA) cubitus anterior;
CuP cubitus posterior;
PCu+1A fused postcubitus and first anal vein;
Sc subcostal;
scr subcostal ridge.
The dorsal surface shows a tuberculate sculpture formed by polygonal cells of cuticle. There are no microtrichia (Fig.
Subcostal ridge and cubital veins are convex, whereas medial and radial sectors look like small depressions. From the wing base to the place where CuA appears, the subcostal ridge is strongly convex and vertical, then the ridge turns closer to the cubital vein. It is still convex but not as much as at the beginning. Scr almost reaches the apex of the wing in that manner (Fig.
There are a few small alar setae (als) at the beginning of subcostal ridge (Fig.
Between the wing base and the concave anal fold there is a small anal lobe (Fig.
The ventral surface also shows a tuberculate sculpture (Fig.
Forewings are semitransparent and are elongate-oval in shape (Fig.
The subcostal ridge almost reaches the apex but turns towards the edge of the wing, so there is no pterostigma. No other vein reaches the wing apex. The costal field of the wing (1, Fig.
The cubital vein, which is strongly pigmented, does not seem to be directly connected with the subcostal ridge - it can be seen underneath as a separate element. The radial sector vein is less pigmented, and the medial vein is hardly visible. At the beginning of the latter, a small, narrow transparent patch is present (marked * in Fig.
The anal fold is a transparent element of the membrane (marked ** in Fig.
The pterostigma is absent.
The wing membrane, at the beginning of sections, is thicker at the proximal part (Fig.
There is certainly no costal vein on cross-sections (which is equivalent to the lack of trachea). It is in contrast to aphid forewings, where a costal vein is present but there are no tracheae (
The subcostal ridge, also known as the subcostal complex, comprises two veins – the subcostal and the radial ones, which run together from the wing base to the apex, where they turn towards the wing margin and disappear. Cross-sections confirm the theory of
The presence of the subcostal vein is note-worthy because it is reported for the first time in a representative of the Sternorrhyncha. Neither aphids (
Darker parts of the membrane, regarded as medial and radial sector veins, are only more pigmented (sclerotized) parts of the wing. Probably they are remnants of veins, as evidenced by
In aphids, radial sector and medial veins are very clearly outlined and in A. fabae the latter is divided into three branches: M1, M2 and M3+4 (
Additionally,
The same author indicated the presence of PCu+1A vein on the edge of the anal lobe, as a synapomorphy for both aphids and coccoids. Likewise,
No archaeococcoids have developed microtrichia, which are characteristic of the wing surface of neococcoids (
Alar setae and campaniform sensilla observed at the subcostal ridge (Fig.
The hypodermal club-shaped thickening (structure similar to pterostigma in other insects) without any veins around (
Comparing forewings in aphids and coccoids, we can conclude that the elements distinctive of coccoids include only two veins, subcostal and radial ones in the common stem and the presence of the wing anal lobe (Table
Based on morphological (
Due to the fact that histological methods revealed only two veins, the subcostal and the radial ones in the subcostal ridge, it seems necessary to change the nomenclature of wing veins for Orthezia urticae Linnaeus 1758. The element known as cubitus anterior vein should be regarded as a convex sclerotized part used only to strengthen the wing and should be marked as “cua”. Two other elements, known as radial sector and medial sector veins, should be marked as “rs” and “m”, but not considered any longer as veins.
Comparison of the forewing structures between a representative of aphids and of coccoids.
Structure | Aphis fabae | Orthezia urticae |
---|---|---|
C | + | – |
Sc | – | + |
R | + | + |
R1 | + | – |
Rs | + | „rs” |
M | + | „m” |
M1 | + | – |
M2 | + | – |
M3+4 | + | – |
CuA | + | „cua” |
CuA1 | + | – |
CuA2 | + | – |
pterostigma | + | – |
common stem | R+M+CuA | Sc+R |
anal lobe | – | + |
The authors are sincerely grateful to Danuta Urbańska-Jasik, University of Silesia, for cross-sections of the wings. We appreciate the critical comments and suggestions of the editor and anonymous reviewer that improved this manuscript.