Bioacoustics of Lirometopum coronatum

Biology, bioacoustics and distribution.— L. coronatum is probably the most easily recognizable cone-head katydid of Costa Rica . Its large, flat face, with characteristic coloration, combined with the relatively large body size and strikingly black abdominal sterna makes the identification very easy. The only species with which it can be confused is Erioloides macrocephalus , but the latter has decidedly longer tegmina, different face markings, and unmistakable ovipositor. L. coronatum can be very common locally, but is rarely seen due to its nocturnal, secretive habits. This species has been recorded from Nicaragua , throughout Costa Rica and Panama to Colombia . In Costa Rica it seems to be absent only in the Pacific portion of the country ( Map 4 ). Both nymphs and adults feed on a variety of plant and animal material but do not seem capable of catching fast moving prey. I have seen adults of L. coronatum feeding at night on seeds of tall grasses as well as fruits and seeds of a variety of shrubs and trees. In captivity they readily accepted corn and sunflower seeds, fruits, vegetables and dead insects . The preferred habitat of this species seems to be the primary lowland wet forest, where it can be found on understory vegetation as well as high in the canopy level. At La Selva Biological Station, L. coronatum can be seen and heard from tall stands of Heliconia at the edge of the forest as well as on low, shrubby vegetation on young succession plots within the primary forest. Males start calling as soon as it gets dark and continue until after midnight. They call from medium thick branches or stems, located at the height of at least 3 m . The call of L. coronatum is readily perceivable by human listeners and consists of short, 5-15 second bouts of chirps, with each bout having 5-10 individual chirps ( 5 males were recorded) ( Fig. 54 A). Each chirp, lasting 95.7-121.1 ms (n=10 at 25°C), consist of 5-9 individual syllables ( Fig. 54 B). Each syllable, lasting 6.7-14.1 ms, displays a shift in the dominant frequency, beginning at about 15-16 kHz and ending at 8-9 kHz (keeping in mind the limitations of the recording technique, it is possible that a similar frequency shift occurs also in higher, not recorded harmonics of the call). The call is low duty, with bouts separated by several seconds to several minutes long periods of silence or substrate tremulation. The substrate transmitted signal consists of two parts. The body shaking, produced at frequency of only 4 Hz, lasts 1.8 seconds, and is followed by a brief, more rapid sequence of tapping of hind feet against the substratum. The tapping sequence lasts about 500 ms and is produced at the frequency of about 10 Hz, with the intensity of tapping gradually decreasing ( Fig. 54 C). The frequency of tremulation bouts increases in the presence of the female but females do not respond with tremulations as females of several species of Copiphora do. The length of copulation has not been recorded. It ends in the male producing a spermatophore with a large, bulbous spermatophylax, which is subsequently eaten by the female. Eggs are deposited in soil, with the number of eggs laid by individual females varying between 9-317 ( Saul-Gershenz 1993 ). Eggs are yellowish-white, slender, about 8.8 mm long ( Fig. 38 B). In captivity, nymphs hatched within 9-122 days after the deposition of eggs. Before the final molt, nymphs underwent 4 molts, and the entire life cycle of individual insects , from hatching until death, spanned 164-529 days ( Saul-Gershenz 1993 ).

Diagnostic description.— General characteristics as described above. Stridulatory file of male 3.2 mm long, with 160 lamelliform teeth, maximum width of file 0.27 mm ; teeth of file uniform in thickness, evenly spaced and smoothly narrowing towards proximal end ( Fig. 42 A). Mirror of stridulatory apparatus somewhat longer than wide, with all margins convex. Face nearly circular, flat; genal carinae strongly tuberculate ( Fig. 11 B); fastigium of vertex about 5 times as wide as scapus, continuous with fastigium of frons; apex of fastigium of vertex distinctly trituberculate ( Fig. 11 C). Male cercus stout, bent inwards, with short, blunt, ventral, subapical spine ( Figs. 11 E-F). Ovipositor longer than hind femur (ratio ovipositor/hind femur 1.42-1.60), straight, upper and lower margins parallel ( Fig. 11 A). Coloration .— Body light green; face with more or less conspicuous yellow, irregular patches, clypeus, labrum and mandibles black; abdominal sterna black in adults (green in nymphs). Measurements (mm). — (males, n=2; females, n=3; minmax, avrg±SD) body with wings: males 45.8-47.3, 46.55±1.1, females 47.6-51.5, 49.5±1.9; pronotum: males 13.6-13.9, 13.75±0.2, females 12.8-13.6, 13.2±0.4; tegmen: males 33.4-33.6, 33.5±0.1, females 33-36.2, 34.3±1.7; hind femur: males 16.6-17.1, 16.85±0.4, females 16.9- 19, 17. 7 ±1.16; ovipositor: 26.6-27.4, 27±0.4.