Conocephalus (Xenocerculus) tuyu, Rubio & Braun, 2024

Rubio, Lucas & Braun, Holger, 2024, A new species of Conocephalus (Orthoptera: Tettigoniidae: Conocephalinae) from Argentina with extraordinarily broad-band ultrasound calling song, Zootaxa 5437 (1), pp. 115-120 : 116-118

Conocephalus (Xenocerculus) tuyu sp. nov.

Examined specimens. ARGENTINA • male (paratype) most probably Córdoba, 2010, M. Pocco ( MLP-OR-3120 ); • male (holotype) Prov. Buenos Aires, Partido La Costa, north of San Clemente del Tuyú, 18.II.2024, H. Braun ( MLP-OR-3242 ); • female (paratype), same locality and day, M. Pocco ( MLP-OR-3243 ); all in the Museo de La Plata .

Etymology. Tuyú is of Guaraní origin, meaning mud or marshland, and is the name of the region in the very east of Buenos Aires Province where the species was found. Noun in apposition, stress on the second u.

Diagnosis. Very small. Mostly green, with reddish brown dorsal band along entire body from fastigium to penultimate abdominal tergite, on head and pronotum with thin white fringes, which turn slightly broader and yellowish on the abdomen, especially in males ( Fig. 1 , 2A,B ). Fastigium distinctly narrower than pedicellus, in diameter hardly exceeding the first flagellomere ( Fig. 2C ). Tegmina in males slightly longer than pronotum, in females shorter than pronotum. All femora without ventral spines. In males fore femora more robust than middle femora and the delicate ventral spines of the fore tibiae blackish, close-fitting to the tibia and forming a line on each ventral edge. In males last tergite in the middle with a pair of small elongate lobules enclosing a narrow gap. Male cerci with moderately slender basal part with obtuse tip, just in front of this tip with a very long and acute internal spine, forming an angle of about 70 degrees to the base and reaching base of opposite cercus ( Fig. 2E,F , Fig. 3B ). Female ovipositor straight, about as long as abdomen or three-fours the length of the hind tibia ( Fig. 1C ).

Measurements. Male: body 13–14 mm, pronotum 2.3–2.4 mm, tegmina 2.6–2.8 mm, hind femora 11–12 mm. Female: body 15 mm, pronotum 3 mm, tegmina 2.5 mm, hind femora 13 mm, ovipositor 9 mm.

Habitat and phenology. Individuals were found in meadows and grassland in or close to sand dunes alongside the beaches of the Atlantic coast, both well preserved or modified by the introduction of exotic trees such as conifers and eucalyptus. There are also observations from Córdoba, near banks of Río Santa Rosa, indicating that it could be a species of coastal and riparian habitats. We found adults from January to March, whereas one of the Córdoba records is from May. The insects appear to be more active during night, leaving the safety of grassland to feed on the inflorescences of native herbaceous plants such as Oenothera mollissima and Solidago chilensis .

Calling song. The male from Aguas Verdes (21.II.2023) produced from 26.II. to 14.III. at night a continuous song with the uniform syllable trains sometimes lasting several minutes. At 26.5°C he made 13.4 syllables per second, although in the natural habitat with lower night temperatures the males certainly call more slowly. No calling activity could be detected during daylight. The short and very soft signal at the beginning of each syllable probably corresponds to the opening stroke of the tegmina (not present at the very end of recorded trains), followed by short crescendos of directly decaying impulses of the closing stroke, most probably corresponding to individual tooth scraper impacts ( Fig. 4A, B ). The carrier frequency spectrum is entirely in the ultrasound and exceedingly broad, from around 25 kHz to 90 kHz ( Fig. 4C ).

Figures

FIGURE 1. Live individuals of Conocephalus tuyu in situ (fromAguas Verdes): A. male (January 2022); B, C. female (February 2023).

FIGURE 2. Conocephalus tuyu (male holotype): A. lateral, B. dorsal view, C. head in dorsal view, D. tegmina (mirror of left tegmen damaged in posterior left corner), E. cerci in dorsal view (right cercus piercing epiproct, right stylus of subgenital plate missing), F. same ventral, vertical scale bars 1 mm.

FIGURE 3. Conocephalus tuyu (male paratype): anterior portion of body and abdomen tip in dorsal view.

FIGURE 4. Calling song of Conocephalus tuyu: A. very short fragment of continuous calling, B. one syllable (26.5°C), C. linear spectrogram.