Bioacoustics of Anisophya (Brevianisophya) arreguii

Acoustic behavior. Even though the katydids were observed moving through the vegetation during the day in their natural habitat, among the captured individuals acoustic activity was only detected at night (the recordings were made from around 21:30 h to shortly after midnight). The males called very continuously, often up to 2–4 minutes, sometimes longer, with short pauses in between. The song consists of syllables which are repeated either more slowly and sometimes irregularly with intervals of 1–3 seconds, or grouped in rapid sequences of different lengths where the syllables directly follow one another ( Fig. 4E , Fig. 5A ). A syllable is made up of a series of rapidly decaying impulses, of which the last ones are considerably louder than the rest ( Fig. 4F ). In the rapid sequences the syllables are somewhat shorter compared to the slower parts of the song, but comprise the same number of impulses, which probably correspond to individual tooth-scraper impacts. Looking at the stridulatory file ( Fig. 2E ), the loud impulses at the syllable end could correspond to the few large teeth between the almost straight distal part and the proximal curvature. The transient impulses produce a broad carrier frequency spectrum, located entirely in the ultrasound with most energy between 30 and 45 kHz ( Fig. 4G , Fig. 5D ). The female responds with short signals right after some of the male syllables, sometimes to several in a row ( Fig. 5B ). The impulse number of these reponses is 2–4, and they were produced with fairly regular intervals after the first loud impulse at the end of the male syllables, in one recorded pair after 80 to 90 ms ( December 2019 , at 23°C), in another after 80–120 ms (mostly 90–100 ms) ( April 2021 , 26°C). The female’s frequency spectrum is also broad, comprising sligthly lower frequencies compared to the male, from 20 to 40 kHz ( Fig. 5E ).

Diagnosis. Fastigium of vertex broad, in frontal view wider than scapus and about twice as wide as pedicellus ( Fig. 3D ). Ventral margin of lateral lobe of pronotum uniformly rounded. Tegmina in females as long as pronotum, in males distinctly longer than pronotum, in females dorsally with densely reticulate venation ( Figs. 2A–C , 3A,B ). Male cerci straight, approximately cylindrical though slightly tapering in lateral view, the tip dorso-ventrally flattened and roundely triangular, with the triangle’s internal angle developed as an acute spinule which is separated by a small rounded gap from the internal end of the cylindrical part right before the flattening ( Fig. 2D ). Ovipositor of female short and strongly upcurved. Coloration uniform, but variable, mostly green, sometimes greyish green or reddish (without any whitish stripes); male stridulatory area mostly brown; in males often fore and middle femora as well as hind femora distally of the enlarged base dark brown ( Fig. 1 ). Comparison. In A. punctinervis the fastigium of the vertex is clearly narrower than in the new species, distinctly narrower than the scapus. In that species the ventral margin of the lateral lobe of the pronotum is more angular compared to the new species, almost straight to the anterior margin of the auditory spiracle, and then more steeply rising to the rear margin. In females the tegmina are shorter than the pronotum (in males as long as or slightly longer than the pronotum) and the venation is rather coarse. Besides, males of the latter species have a green stridulatory area and sport whitish lateral stripes, one running from behind the eye, across the lateral lobe of the pronotum, the costal margin of the tegmen, and along the abdomen up to its end, and another one near the ventral margins of the abdominal tergites, whereas in the uniformly colored females only the costal margin of the tegmina is sometimes whitish. A. brasiliensis can be distinguished from the new species by white lateral stripes on the pronotum in males and a much longer and only little curved ovipositor in females. Males of both A. punctinervis and A. brasiliensis have simple cerci, without any gap between terminal spinule and basal part.