Neoconocephalus, Karny, 1907

Piotr Naskrecki, 2000, Katydids of Costa Rica / Vol. 1, Systematics and bioacoustics of the cone-head katydids (Orthoptera: Tettigoniidae: Conocephalinae sensu lato)., Philadelphia, PA: The Orthopterists Society at the Academy of Natural Sciences of Philadelphia, : 50-55

NEOCONOCEPHALUS Karny, 1907

1907 Karny, Abh. Zool.-bot. Ges. Wien 4(3): 22; type species: Conocephalus subulatus Bolivar, 1881 (type lost).

1999 Naskrecki and Otte, Illustr. Cat. Orthop. I (CD ROM) >>catalog of species

Diagnosis

Body slender; both sexes macropterous ( Figs. 12 A, 37E); tegumen smooth to moderately rugose. Fastigium of vertex broader than scapus, usually short and blunt; no traces of genal carinae present; frons flat or weakly convex; eyes small. All legs slender, armed on lower margins with minute spines. Male cercus armed apically with 2 incurved spines; ovipositor straight, with upper and lower margins parallel.

Description (male except where specified)

Head.— Fastigium of vertex 2 to 3 times as wide as scapus, blunt and 1.1 to 1.3 times as long as diameter of eye (Costa Rican species only; fastigium of vertex greatly enlarged in some North and South American species); fastigium of vertex separated from fastigium of frons by small gap, rarely fastigia touching ( Figs. 13 A-H). Eyes small relative to size of head, weakly protruding. Frons flat or weakly convex, smooth; tegumen of head smooth to weakly rugose, without traces of genal carinae; face slender. Mandibles and labrum weakly asymmetrical (right mandible smaller).

Thorax and wings.— Dorsal surface of pronotum smooth to weakly rugose, flat; anterior dorsal margin straight, posterior one convex; lateral lobes with posterior angle broadly rounded ( Fig. 12 D); humeral sinus well developed. Thoracic auditory spiracle large, elliptical, completely hidden under lateral lobe of pronotum; posterior edge of spiracle with small, finger-like projection. Prosternum armed with two thin, widely separated spines (modified basisternum); meso- and metasternum with lateral lobes of basisterna triangular, their inner margins touching.

Wings in both sexes fully developed, extending well beyond apices of hind femora ; tegmina slender. Stridulatory apparatus of male well developed; stridulatory area of left wing thickened, with dense network of secondary veinlets; stridulatory file (vein AA 1) straight to weakly curved ( Figs. 44 A-H), in most species stridulatory teeth strongly narrowed towards proximal (inner) end of file, and wider and thicker towards distal (outer) end of file; mirror of right wing longer than high, with weak veinlet closely parallel to or divergent from AA 1 ( Figs. 45 A-D); caudal margin of mirror straight or rounded. Posterior margin of tegmen weakly concave; apex of tegmen narrowly rounded.

Legs.— Fore coxa with an elongate, forward projecting spine dorsally. Fore and mid femora unarmed dorsally, but armed ventrally on anterior margins (sometimes both ventral margins of fore femur unarmed); genicular lobes of femora unarmed or armed with short spines; often only inner genicular lobes armed. Fore and mid tibiae unarmed dorsally, both ventral margins with immovable spines as long as 1/4 to 1/2 diameter of tibia; hind tibia armed on all four dorsal and ventral margins; apex of tibia with two pairs of ventral and one pair of dorsal movable spurs. Tympanum on fore tibia bilaterally closed, tympanal slits facing forward, tympanal area only weakly swollen, with pair of small, elongated pits below tympanal slits.

Abdomen.— Dorsal surface of abdominal terga smooth, unmodified. Male 10th tergite with shallow apical emargination, supraanal plate small, triangular. Male cercus with 2 apical spines, both bent inwards under right angle; upper spine 1/3 to 1/2 as long as lower spine; both spines with apices curved downwards when seen from behind ( Fig. 12 E); female cercus, simple, slender and weakly incurved. Subgenital plate of male with a pair of styli, distinct median keel, and shallow, triangular apical emargination; female subgenital plate with shallow apical emargination.

Male concealed genitalia without well developed titillators but with part of phallic membrane partially sclerotized and covered by chitinous callosities. Ovipositor narrow, straight or weakly curved down; as long as or longer than hind femur; both dorsal and ventral margins of ovipositor smooth, parallel; apex of upper valvula sharp, slightly thickened.

Coloration.— Coloration in species of Neoconocephalus is extremely variable and, with the exception of the color markings on the fastigium of vertex, unreliable as a taxonomic character. Nearly all, or possibly all species have two, green and brown, color forms, both with numerous variations of shade and darkness. In several species mandibles are orange and some femoral spines are accompanied by black basal spots. Brown forms of several species have tegmina mottled with dark dots, and often veins R and M of tegmina are darker than the remainder of the wing ( Fig. 37 E). The resulting dark stripe is continuous with darker lateral lobes of the pronotum.

Remarks.— The genus Neoconocephalus belongs to some of the most problematic, from the taxonomic point of view, genera of Tettigoniidae . It currently includes over 100 named species, descriptions of most of which were based on single or very few specimens, often only females. The nearly complete uniformity of genitalic characters in the species of the genus, combined with the great intraspecific variation of coloration, and the recently recognized occurrence of cryptic and acoustically isolated sympatric species ( Walker, Whitesell and Alexander 1973), makes identification of the forms described by older authors very difficult or downright impossible. Walker and Greenfield (1983) discussed problems with the identification of Caribbean species of Neoconocephalus , and concluded that of 36 names available to them, only 8 could be considered valid, with the rest being either junior synonyms or nomina dubia. In light of the above, most of the older literature records of Neoconocephalus should be treated with great caution as they may represent cases of misidentification.

The only non-molecular characters considered reliable for identification of species of Neoconocephalus are those of the sound produced by males, and associated morphological features of the stridulatory apparatus, such as the shape and length of the stridulatory file, the number and shape of stridulatory teeth, and features of the mirror. Less reliable, albeit considerably easier to examine, are the shape and color markings of the fastigium of vertex. The latter also allow one to identify females, which otherwise could only be identified by association with male individuals. This character, however, is also subject to a substantial degree of intraspecific variation and should not be used as the only and decisive character while identifying specimens of Neoconocephalus .

Distribution and biology.— The geographic distribution of species of Neoconocephalus covers temperate and tropical zones of the New World, from south-eastern Canada through Central America to Chile and Argentina. The closest relative of the genus Neoconocephalus , genus Ruspolia Schulthess is widely distributed in temperate and tropical areas of the entire Old World. As pointed out by Bailey (1975, 1979) and Walker and Greenfield (1983), these genera can only be separated based on their geographic distribution since neither displays consistent morphological characteristic warranting separate generic status. A similar problem applies to the chiefly Indo- Australasian genus Euconocephalus Karny , species of which, based on morphological criteria, could be assigned equally well to either Neoconocephalus or Ruspolia . Once undertaken, a critical phylogenetic revision of the three genera will probably reveal that they form a monophyletic unit, with species from all three genera occurring together on different branches of the clade.

In Costa Rica, species of the genus Neoconocephalus are distributed over the entire country, at elevations ranging from sea level to 1700 m. It is quite possible that they will also be found at higher elevations in the Talamanca Range once a more extensive collecting effort is undertaken. The preferred habitats for most species of the genus are open or semi-open grasslands, pastures, clearings, and grassy hill slopes. At least one species, N. affinis , also occurs along paths in both primary and secondary forest. In the lowland Atlantic rainforest at La Selva Biological Station, it is not uncommon to find males of this species singing along with males of Copiphora rhinoceros from the same bush at the edge of the primary forest. The same species can also be found in open clearings and pastures with other species of Neoconocephalus and Conocephalus , as well as in swamps within the forest, alongside Caulopsis microprora .

There is no apparent seasonality in the development of Costa Rican species of Neoconocephalus , and both adults and nymph can be observed all year round. Greenfield (1990) reports that Panamanian populations of N. triops , a species that also occurs in the United States where it produces two generations per year and undergoes a diapause, show no signs of diapause. This is indicated by the presence in those populations of only one type of song, the “summer song,” while winter and summer generations (the winter generation undergoes a diapause) of the northern populations produce two distinctive types of song.

Little is known about the diet of Costa Rican species of Neoconocephalus , but it seems that most or all species feed on a variety of grass species, eating both the leaves and seeds. In captivity they also accept fruits and dead insects.

Males of Costa Rican species start singing at dusk and continue through the night. N. affinis and N. punctipes may also sing during the day but usually only from shaded locations such as edges of trails within a forest. Males of N. spiza will switch from nocturnal to diurnal singing in places with high densities of congeneric species. In this species females stop responding phonotaxically to the male’s call if calls of other species of the genus interfere with it ( Greenfield 1997). Singing males may either sit close to the ground, in tufts of grass, or, especially within the forest, on branches of low shrubs. In areas where grass is exceptionally tall, males sing more often from the tops of the grass rather than from their bases. The call of most species is a high duty, low Q call, with the principal frequencies between 9 and 16 kHz. The call usually consists of long (up to several minutes) bouts of continuous rattling or buzz, which from a close distance can have an ear-piercing effect on human listeners. Less frequently the song consists of series of short, buzzy chirps ( N. spiza ). In several species males form choruses and synchronize their songs (for an excellent review of this behavior see Greenfield 1990).

Copulation in some Neoconocephalus spp. is sometimes accompanied by bouts of substrate vibration ( Gwynne 1977), although I have not seen this behavior in Costa Rican species. The spermatophore passed onto the female by the male during copulation is small and lacks a visible spermatophylax. Oviposition takes place in stems of grasses.

Figures

FIG. 11. Lirometopum coronatum. A. female - habitus, B. female face, C. female head and pronotum, dorsal view, D. female abdomen and subgenital plate, ventral view, E. male cerci, dorsal view, F. apex of male abdomen, posterior view.

FIG. 12. Neoconocephalus affinis. A. male - habitus, B. head fastigia, lateral view, C. head fastigia, frontal view, D. male cerci, dorsal view, E. male head and pronotum, dorsal view.

FIG. 13. Frontal and lateral view of fastigia of Costa Rican Neoconocephalus spp. A-B. N. triops, C-D. N. punctipes - form without a fastigial gap, E-F. N. punctipes - form with a fastigial gap, G-H. N. cf. spiza.

FIG. 37. Costa Rican species of Conocephalinae s. l. A. Erioloides longipennis - female ovipositing, B. Erioloides longinoi - male, C. Eriolus penicillus - female, D. Conocephalus cinereus - male, macropterous form, E. Neoconocephalus triops - male, brown form, F. Sphyrometopa atlantica - male, inset - nymph.

FIG. 43. Stridulatory files of Costa Rican species of Conocephalinae s. l. A. Copiphora cochleata, B. Copiphora rhinoceros, C. ditto, enlarged fragment, D. Acantheremus colwelli, enlarged fragment, E. ditto, entire file, F. Metacaputus brenesi.

FIG. 44. Stridulatory files of Costa Rican species of Neoconocephalus. A. N. affinis, B. ditto, enlarged fragment, C. N. triops, enlarged fragment, D. ditto, entire file, E. N. punctipes, entire file, F. ditto, enlarged fragment, G. N. cf. spiza, enlarged fragment, H. ditto, entire file.

FIG. 45. Stridulatory areas of Costa Rican species of Neoconocephalus, dorsal views, left and right sides. A. N. affinis, B. N. triops, C. N. punctipes, D. N. spiza.

FIG. 53. Oscillograms of male airborne calls of Costa Rican species of Conocephalinae s. l. A. Conocephalus ictus, B. ditto, 0.5 s fragment, C. C. magdalenae, D. ditto, 0.5 s fragment, E. Orchelimum fraternum, F. ditto, 0.5 s fragment, continuous part, G. Erioloides brevipennis, H. ditto, 0.35 s fragment.

FIG. 54 Oscillograms of male airborne calls and substrate tremulations of Costa Rican species of Conocephalinae s. l. A. Lirometopum coronatum, airborne call, B. ditto, 0.5 s fragment, C. ditto, substrate tremulations and feet drumming, D. Acantheremus colwelli, E. ditto, 0.5 s fragment, F. Copiphora rhinoceros, G. ditto, 0.5 s fragment.