Corythucha, Stal, Stal, 1873

Montemayor, Sara I., 2009, Description of a new Corythucha Stål from Argentina (Hemiptera: Heteroptera: Tingidae), with a description of its life cycle, Zootaxa 2170 (1), pp. 61-68 : 62-68

Description of the egg ( Figs. 1, 3, 4 )

Brown to brownish black; operculum light brown; subelliptical, widest towards the apex, tapering towards the base where it is inserted in the leaf tissue. Chorion smooth, shiny. Operculum cone-shaped.

Description of the first instar ( Fig. 5 )

Body slender, dark brown, antennae and legs yellow. Body length: 0.40–0.58 (0.49); width: 0.15–0.23 (0.20).

Antennae covered with a few long, scattered hairs; antennal segment I approximately the same length as II but stouter, III longer and slender than other segments, IV stout and fusiform. Antennal segment measurements: I: 0.03; II: 0.04; III: 0.06–0.08 (0.07); IV: 0.08. Head length: 0.11–0.15 (0.13), width: 0.08–0.15 (0.13). Head armed with five tubercles, a frontal pair, a median unpaired and an occipital pair. Frontal pair of tubercles simple, divergent; median ramified in branches; occipital pair ramified in branches, subparallel.

Pronotum slightly expanded laterally, short and moderately wide, lateral margins unarmed. Mesonotum short, moderately wide; posterolateral margins with one long simple tubercle. Metanotum short and moderately wide, margins unarmed.

Each abdominal segment has a simple long tubercle on the posterior lateral margins. Tergites II, V, VI, and VIII with a pair of dorsal simple, divergent tubercles.

Description of the second instar ( Fig. 6 )

Body moderately broad, dark brown, antennae and legs yellow. Body length: 0.63–0.68 (0.65); width: 0.38–0.44 (0.40).

Antennal segment I longer and stouter than II. Antennal segment measurements: I: 0.04–0.05 (0.05); II: 0.03–0.04 (0.04); III: 0.07–0.09 (0.09); IV: 0.09–0.11 (0.10). Head length: 0.15–0.18 (0.16), width: 0.20–0.22 (0.21). Occipital pair of cephalic tubercles divergent, all other cephalic tubercles characteristics same as previous instar.

Pronotum anteriorly produced, anterolateral margins armed with small simple tubercles, posterolateral margins armed with a bigger ramified tubercle. Mesonotum with a pair of median ramified tubercles, divergent, and directed posteriorly. Metanotum with same characteristics as previous instar.

Abdominal segments with same characteristics as previous instar.

Remarks: In the previous instar the first and second antennal segments are subequal in length; from this instar onwards the first antennal segment is longer than the second. Some new spines are developed in the lateral margins of the pronotum and in the mesonotum.

Description of the third instar ( Fig. 7 )

Body broad; dark brown except for antennae, legs, and middle portion of metanotum yellow. Body length: 0.85–0.98 (0.90); width: 0.43–0.50 (0.48).

Antennae with same characteristics as previous instar. Antennal segment measurements: I: 0.03–0.05 (0.03); II: 0.03–0.05 (0.04); III: 0.13–0.18 (0.15); IV: 0.09–0.13 (0.11). Head length: 0.18–0.20 (0.18), width: 0.20–0.30 (0.23). Cephalic tubercles with same characteristics as previous instar.

Pronotum with two pairs of median simple divergent tubercles; pronotal margins with same characteristics as previous instar. Mesonotum with same median tubercles as previous instar; anterolateral margins armed with a simple tubercle, posterolateral margins with a ramified tubercle. Metanotum with same characteristics as previous instar. Length of wing pads: 0.08–0.13 (0.11).

Abdominal tergites II and VIII with same tubercles as previous instar; tubercles of segments V and VI ramified.

Remarks: In this instar the thorax becomes more complex; some new spines appear in the pronotum and on the mesonotum lateral margins. The complexity of the abdominal tubercles corresponding to the segments III and IV increases; in the previous instars tubercles were not ramified.

Description of the fourth instar ( Fig. 8 )

Body length: 1.15–1.40 (1.25); width: 0.65–0.75 (0.72). Antennal segment measurements: I: 0.04–0.08 (0.06); II: 0.04–0.06 (0.05); III 0.25–0.44 (0.33); IV 0.15–0.19 (0.17). Head length: 0.18–0.25 (0.23), width: 0.28–0.35 (0.30). Cephalic tubercles with the same characteristics as previous instar.

Pronotum anteriorly produced, slightly elevated and posteriorly produced over abdomen; anterolateral margins armed with two or three small simple tubercles, posterolateral margins armed with a larger ramified tubercle. Meso- and metanotum with same characteristics as previous instar. Length of wing pads: 0.23–0.30 (0.25).

Abdominal tergites with same characteristics as previous instar.

Remarks: In this instar the hood and the posterior process begin to become obvious. The pronotum is more elevated anteriorly and it is anteriorly and posteriorly produced. The lateral margins of the pronotum and mesonotum are armed with more tubercles.

Description of the fifth instar ( Fig. 9 )

Body length: 1.65–1.88 (1.77); width: 1.00–1.15 (1.06).

Antennal segment measurements: I: 0.09–0.13 (0.10); II: 0.06–0.08 (0.07); III: 0.38–0.44 (0.41); IV: 0.20–0.25 (0.25). Head length: 0.18–0.25 (0.22), width: 0.33–0.40 (0.35). Cephalic tubercles with the same characteristics as previous instar.

Pronotum develops median carina, this swollen and anteriorly projected to form a hood, all other characteristics same as previous instar. Meso- and metanotum with same characteristics as previous instar. Length of wing pads: 0.63–0.68 (0.65)

Abdominal tergites with same characteristics as previous instar.

Remarks: The main difference between the fifth and fourth instars is the development of the median carina and the hood more elevated and anteriorly produced.

Comments. The nymphs of Corythucha can be clearly distinguished from nymphs of other genera. Guilbert (2005) described the tubercles of Corythucha as: “short, with ramifications bunchlike, made of a short and stout peduncle from where merge four simple spiny branches with a pestle-like ampulla at the apex, and along setae at the base,” and remarks that they have not been observed on other genera. In nymphs of other species such as C. arcuata , C. ciliata , C. marmorata , C. mcelfreshi , and C. pergandei the number and disposition of the thoracic and abdominal tubercles present the same pattern. Unless nymphs are caught together with adults it is almost impossible to identify the species, as they are all very similar ( Guilbert, 2005).

Most tingids feed on the underside of leaves, and may cause desiccation of tissue and defoliation of the tree. Both nymphs and adults present aggregational feeding behaviour. The adults of C. bonaerensis overwinter under the loose bark of trees. Between November and December, when temperatures rise, the adults leave their winter refuge to start feeding on the underside of leaves. The eggs are inserted into the tissue of the abaxial surface of the leaf at right angles. They are laid close to one another ( Fig. 1 ) and between the veins of the leaves; each cluster generally contains over twenty eggs. The nymphs are gathered together on the main veins ( Fig. 2 ), but can occupy the entire leaf when many individuals are present. Soon, as a consequence of the feeding activities, the entire areas where the nymphs feed turn yellowish and finally brown.

Nymphs stay close together at first, only moving to new leaves after they reach the fourth instar. Different nymphal stages are mixed in each set of individuals. When stimulated with light, nymphs run away and form new aggregations with nymphs of early stages (I, II, and III) or late stages (IV and V). Between March and April when temperatures start dropping, adults hide under the loose bark of trees, or in nearby cracks and crevices.

Description of the adult ( Fig. 10 )

Diagnosis: A medium-sized species, between 3.25 and 3.65 mm; hood gradually narrowing anteriorly; pronotal lateral carinae present, elevated, anterior extreme of these carinae far away from the hood; median carina arched with two rows of areolae; posterior process well developed; hemelytra with a transverse basal dark band, costal and sutural areas hyaline; anterior half of hemelytral margins armed with small tubercles.

Description: General color yellowish. Body length: 3.25–3.65 (3.50) 3.25–3.50 (3.40). Antennal segment measurements: I: 0.22–0.25 (0.25) 0.20–0.27 (0.25); II: 0.10 (0.10); III: 0.75–0.77 (0.76) 0.70–0.80 (0.75); IV: 0.22–0.27 (0.24) 0.22–0.27 (0.25). Hood length: 0.80–0.95 (0.90) 0.75–0.95 (0.90). Head completely covered by hood.

Pronotal disc brown becoming posteriorly paler, finely pitted, tricarinated; median carina higher than lateral carinae, arched ( Fig. 11 ), with two rows of areolae; lateral carinae scarcely reaching the pronotal disc, anteriorly convergent. Paranota hyaline, sometimes with one or two irregular brownish spots, wide, subhorizontal, anteriorly rounded with five rows of medium-sized areolae, margins armed with tubercles. Hood surpassing anterior margin of head, posteriorly subglobose, anteriorly and gradually narrowing. Rostrum reaching posterior half of mesosternum. Rostral laminae composed of one row of areolae; mesosternal laminae posteriorly diverging. Metathoracic scent gland present.

Hemelytra length: 2.15–2.30 (2.22) 2.20–2.30 (2.25). Discoidal area length: 0.95–1.05 (1.00) 0.90–1.05 (0.95). Hemelytra hyaline, costal area with a transverse dark basal band and an oblique dark area distally, discal elevation dark brown; anteriorly reflexed immediately after abruptly widened; margins armed with tubercles on anterior half. Costal area with three rows of large areolae. Subcostal area with two rows of areolae. Sutural area composed of medium sized irregular areolae.

Etymology: The derivation of the specific epithet refers to the Buenos Aires province, where the holotype was collected.

Comparison with the other South American species

There are eighteen other South American species of the genus. The main differences with C. bonaerensis are:

1.- Corythucha argentinensis Monte , C. pellucida Drake & Hambleton , and C. tapiensis Ajmat can be easily distinguished from C. bonaerensis by the absence of lateral pronotal carinae.

2.- Corythucha gossypii (Fabricius) , C. nocens Drake & Hambleton , and C. socia Monte are small species that never measure more than 3 mm; C. seguyi Drake is particularly large and always measures more than 4.5 mm; in contrast C. bonaerensis is a medium-sized species that measures more than 3 mm but never reaches 4 mm.

3.- The posterior process is normally developed in C. bonaerensis ; unlike C. boliviana Monte and C. nocens , in which the process is very short.

4.- Corythucha acculta Drake & Poor , C. nobilis Drake & Bondar , and C. globigera Breddin can be recognised because the anterior extreme of their lateral carinae are very close to the hood, whereas in the rest of the South American species the anterior extreme of the lateral carinae are far from the hood.

5.- The hemelytra of C. bonaerensis present a transverse dark band at the base of the costal area and the sutural area hyaline; in C. ciliata (Say) the base of the costal area is hyalinae without a dark band, and in C. palmatis Drake the sutural area is brownish.

6.- The median carina in C. bonaerensis has two rows of areolae and the paranota are hyaline even though it may have one or two irregular brownish spots; in C. rolstoni Ajmat the median carina has only one row of areolae and the paranota always have two irregular brownish spots.

7.- The shape of the hood is another character useful to distinguish C. bonaerensis from other South American species such as C. clara Drake & Hambleton , C. socia , and C. translucida Monte , and C. nocen s, because in these species the hood is strongly constricted and in C. bonaerensis the hood gradually narrows forward.

8.- In C. fuscomaculata (Stål) the anterior two-thirds of the hemelytral margins are armed with moderately long tubercles; in contrast in C. bonaerensis only the anterior third of the hemelytra is armed with shorter tubercles.

Comparison with the other species in the world that feed on Quercus

Only four other species have been recorded for the genus Quercus : C. arcuata (Say) known from Canada ( Uhler, 1884), Italy (Bernerdinelli & Zandigiacomo, 2000), Switzerland ( Forster et al, 2005), Turkey ( Mutun, 2003), and U.S ( Say, 1832); C. cerasi Drake from U.S. ( Drake, 1948); C. cydonea (Fitch) from Canada ( Gibson, 1918), Mexico ( Drake & Ruhoff, 1965), and U.S. ( Fitch, 1861); and C. floridiana Heidemann from U.S. ( Heidemann, 1909).

1.- Since the original description of C. arcuata there has been confusion about the identity of this species, the type is lost ( Drake & Ruhoff, 1965) and the original description is vague and could correspond to several different species.

2.- In C. cerasi the hood is strongly constricted and is four times higher than the median carina; in C. bonaerensis the hood is not constricted and is about one and a half times higher than the median carina.

3.- In Corythucha cydonea the hood very high, nearly three times higher than the median carinae, and the hind portion of the hood is very globouse; in C. bonaerensis the hood is lower, approximately one and a half times higher than the median carina, and the hind portion of the hood is subglobouse.

4.- Corythucha floridiana is a very small species, between 2.3 mm and 2.6 mm approximately; C. bonaerensis is a larger species, measuring more than 3 mm.

Figures

FIGURE 1–4. 1, Eggs cluster on leaf; 2, Nymphs gathered on main veins of the leaf; 3, Operculum of egg; 4, Egg view.

FIGURE 5–7. 5, Nymph I; 6, Nymph II; 7, Nymph III.

FIGURE 8–11. 8, Nymph IV; 9, Nymph V; 10, Adult; 11, Lateral view of the hood and median carina.