Roeseliana Zeuner, 1941

Massa, Bruno, Tagliavia, Marcello, Buzzetti, Filippo Maria, Fontana, Paolo, Carotti, Giovanni, Bardiani, Marco, Leandri, Fausto, Scherini, Roberto & Verde, Gabriella Lo, 2023, A taxonomic revision of the Palaearctic genus Roeseliana (Orthoptera: Tettigoniidae: Tettigoniinae: Platycleidini): a case of ongoing Mediterranean speciation, Zootaxa 5270 (3), pp. 351-400 : 356-357

Genus Roeseliana Zeuner, 1941

Morphological analysis

Characters of the genus Roeseliana

The genus Roeseliana was described by Zeuner (1941), who named it after the Austrian entomologist August Johann R̂sel von Rosenhof. However, several authors preferred to maintain Roeseliana as subgenus of the genus Metrioptera Wesmael, 1838 . More recently, Massa & Fontana (2011) carried out a revision of Platycleidini and raised again Roeseliana to generic level. According to previous authors ( Zeuner 1941; Massa & Fontana 2011), these are the characters of the genus: head slightly broader than long, ratio maximum width/length of head (from vertex to clipeus): 1.2–1.3. Brachypterous, rarely holopterous, pronotum flat, just depressed, margins rounded, humeral excision just evident, keel present in the metazona; ♀ subgenital plate large, bilobate, at the sides not touching the ovipositor; ovipositor short and clearly curved, somewhat angular at 1/3 from the base; ♀ VIIth sternite modified or not; hind femora/pronotum length ♁: 2.7–3.5, ♀: 2.7–3.6; ♁ Xth tergite with very broad processes separated by an incision, long cylindrical cerci, with a pre-apical inner spine. Colour of lateral lobes of the pronotum greyish bordered with a whitish stripe.

Diagnosis. Tenth tergite of male with very broad anal segment, rounded cerci and short ovipositor are useful characters to separate Roeseliana from Metrioptera and Bicolorana Zeuner, 1941; with the latter Roeseliana shares the female subgenital plate not touching the ovipositor.

Ovipositor— Figs. 1–2 , Table 2

The shape of the ovipositor is fairly variable, but we could find taxa/populations with fine ovipositor ( R. pylnovi , R. roeselii , R. azami minor from Lombardy, Piedmont and Emilia-Romagna, R. ambitiosa ), and those with deeper ovipositor ( R. azami , R. azami minor from Tuscany and Marche, R. brunneri and R. bispina ). However, the ovipositor angle resulted also variable in the different taxa/populations, smaller in R. pylnovi , R. oporina , R. azami , R. azami minor from Lombardy, Piedmont, Emilia-Romagna and Tuscany, R. brunneri and R. bispina , bigger in others, namely R. roeselii , R. azami minor from Marche and R. ambitiosa .

Stridulatory file— Fig. 3 , Table 2

We describe preliminary the stridulatory file of different taxa/populations, that are very similar in their structure ( Fig. 3 ). The length is ca. 1.2 mm, while the depth may range from 0.20 to 0.35 mm. Stridulatory file is a little arched, the total number of teeth ranges between 40 and 80 ( R. brunneri : ca. 70–80 with 15 central larger; R. azami minor from Tuscany: ca. 50 with 15 central larger; R. azami minor from Piedmont: ca. 40, with 15 central larger; R. azami : ca. 45, more or less of the same size; R. roeselii : ca. 50, with 12–13 central larger teeth; R. ambitiosa : ca. 50 with at least 40 teeth of more or less the same size and a few very small teeth in the proximal part; R. bispina : ca. 60, more or less of the same size; R. pylnovi : ca. 50, with 12–13 central larger). Generally, the stridulatory file in its proximal part bears very small teeth (about 15–20), dense, decreasing in size and evenly spaced, the central part is composed of ca. 12–15 widely spaced larger teeth (with some exceptions, like in R. azami , R. bispina and R. ambitiosa ), the distal part is composed of about 8–10 very small teeth. The differences are noted in Table 2 .

Female subgenital plate— Figs. 8 , 9 , Table 2

The ratio length to width of the female subgenital plate resulted to be maximum in R. pylnovi (2.8), followed by that of R. roeselii (2.0–2.1), R. azami minor from Marche (2.1–2.2), R. oporina (1.8), R. azami minor from Lombardy, Piedmont and Emilia–Romagna (1.8–2.2), R. brunneri (1.7–1.9), R. azami (1.7), R. azami minor from Tuscany (1.7), R. bispina (1.7) and R. ambitiosa (1.5). However, other differences in the shape of the apical tips of the subgenital plate are evident.

Figures

FIGURE 1. Ovipositor of five taxa of Roeseliana in lateral view. In 1c the method to take three measures of the depth of the ovipositor (named “ovipositor depth” in the text) is explained.

FIGURE 2. Ovipositor of three other taxa of Roeseliana (different populations) in lateral view. In 2a the method to measure the angle between the base of the ovipositor and a line intersected between it and the ovipositor tip (named “ovipositor angle” in the text) is explained.

FIGURE 3. Stridulatory file under the left tegmen of some taxa of Roeseliana.

FIGURE 8. Ventral view of the female subgenital plate of six taxa of Roeseliana.

FIGURE 9. Ventral view of the female subgenital plate of other two taxa of Roeseliana (different populations).