Cohnia andeana ( Hebard, 1924 ) Buzzetti & Fontana & Carotti, 2010

Buzzetti, F. M., Fontana, P. & Carotti, G., 2010, Bioacoustic of Cohnia andeana (Hebard, 1924) comb. nov. (Insecta: Orthoptera: Tettigoniidae), Zootaxa 2661 (1), pp. 59-68 : 61-67

Cohnia andeana ( Hebard, 1924) comb. nov.

Dichopetala andeana Hebard, 1924: 195 .

Dichopetala andeana: Rehn, 1955: 1 .

Type locality and type material: Ecuador, Loja province, Loja. Elevation 7284 feet (2220 meters), (F. Campos Leg. ) (Hebard Collection, Type no. 979, ANSP) 1♂ type, 1♀ allotype, 4♂ and 2 ♀ paratypes .

Material examined: Ecuador, Loja prov., Catamayo , 1500 m, 27–28/IV/2005, 11♂, 21♀. G. Carotti & B. Agabiti leg., FMB; idem, 4♂, 6♀, PF ; Ecuador, Loja prov, Catamayo , 1653 m, S 03°59’37.7’’ W 079° 19’ 45.9’’, 1/V/2006, 4♂, 4♀. F. M. Buzzetti, G. Carotti & A. Marzotto leg., FMB; idem, 1♂, PF .

Redescription. Male ( Fig. 3 ): Head round with fastigium weakly developed. Pronotum ( Fig. 5, 6 ) smooth without humeral sinus, typical sulcus behind the middle, fore and hind margins of pronotal disc straight, the fore sometimes more or less emarginated. Tegmina ( Fig. 5, 6 ) squamiform, ovate, with campus mediocubitalis constituting about half of tegmen total length. Hind wings extremely reduced but present. Stridulatory file ( Fig. 20 , 30, 31 ) about 1,5 mm long and with about 60 pegs arranged in a regularly curved row. The size of the stridulatory pegs decrease while their density increase toward the proximal end of the file. Genicular lobes unarmed, except for the lower lobes of fore and mid legs bearing a very small spine, in some case also the upper genicular lobe bears a very small spine. Tenth tergite ( Fig. 16 , 27 ) caudally emarginated and impressed. Epiproct caudally rounded. Cerci ( Fig. 9, 11–13, 16 , 27 ) distally tapering in a blunt dark tooth, apical third inward curved. Subgenital plate ( Fig. 10 ) tricarinated, apically emarginated. Internal genitalia ( Fig. 18, 19 ) more or less sclerotized, titillators-like.

Female ( Fig. 4 ): Same as male, except for larger size. Tegmina without stridulatory apparatus. Cerci ( Fig. 14 ) conical. Ovipositor ( Fig. 15 ) with distal half serrulated, more strongly on the distal third. Subgenital plate ( Fig. 21, 24 ) entire, basal and distal margins emarginated, lateral margins convex, apex truncated, longitudinally carinated in the middle.

Colour: The specimens we examined closely agree with original description ( Hebard 1924). Most of the specimens are dark olive green in general coloration, only three are completely green. Dorsal colour deeper than in lateral body surface.. Pronotal disc with median longitudinal yellow line. Lateral carinae of pronotum white. More or less defined trapezoidal markings are present on the middle of each abdominal tergite. Limbs green except in the darker specimens in which the legs are almost completely black. Male cerci completely yellow, except for the apical black tooth. Ovipositor green, in melanic females the apex is darker.

FIGURES 32–33. Oscillogram of C. andeana . 32: calling song; 33: echemes.

Measurements of male: body length 17.84–13.57 (15.70), pronotum length 3.37–2.59 (3.08), caudal width of pronotum 3.18–2.55 (2.89), tegmina length 3.75–3.15 (3.42), hind femur length 16.73–14.52 (15.93), cerci length 1.5–1 (1.33).

Measurements of female: body length 23.69–18.71 (21.27), pronotum length 3.75–2.75 (3.16), caudal width of pronotum 3.15–2.62 (2.88), tegmina length 3.65–3 (3.28), hind femur length 17.25–14.56 (16.29), ovipositor length 7.12–5.69 (6.25).

Ecology. During recent expeditions in Ecuador, an abundant population of D. andeana was found in locality Catamayo, 35 km West of Loja.

In the area ( Fig. 2 ), the species inhabits the “paramo arbustivo” environment with very dense vegetation of bushes and low trees. Specimens were collected on all kind of vegetation, from the lowest grasses to the bushes, except of the arborescent vegetation. Many individuals were found also on the grassy vegetation along the road to Loja.

The new collecting locality is different, at a lower elevation, from the type locality. According to the information given by Hebard (1924), the type locality is “ Loja ”, more probably in the surroundings of the town. However the actual environments near Loja are different from that of the new locality, being characterized by vegetation typical of higher elevation. No researches has been carried in the higher surroundings of Loja and it’s not possible to say if the species still inhabits the places near Loja.

The 27–28 April 2005, during 2 hours of visit in the locality, 42 adult specimens of the species has been observed and collected (13 males and 29 females), 5 young females were observed but not collected.

One year later, the first May 2006, 28 adult individuals were observed (17 males and 11 females), 3 young females observed.

In the original description, no information are given on the collecting period of the type material. Our samplings in the locality where C. andeana is present, were carried on February, April and May. Since in February no individuals were noted, neither adult nor young, the phenology of the species appears to be restricted to the dry season months, from late April to September approximately. Further samplings during the end of the dry season are necessary to determine the true phenology of the taxon.

Bioacoustics. The song (Fig. 32, 33) of Cohnia andena comb. nov. consists of short series of paired polysyllabic echemes audible by the unaided ear. Such paired echemes are repeated 3–4 times in 3–4 sec, each pair of echemes lasts for 0.35 sec and is separated from the following by an interval of 1.9–2.4 sec. Echemes are composed by 4–8 dyplosyllables of different intensity and last for 0.03–0.05 sec. Diplosyllables consist of hemisyllables apparently equal in length (about 0.001 sec).

This song structure is different from that observed in Dichopetala s. str., confirming the generic diversity of Cohnia g. nov.

Singing activity was observed in laboratory conditions only during a restricted time in the morning, approximately between 9 and 11 a.m., with natural light. All the song emitted by males in different conditions, alone or with other male or female specimens in the same cage, were similar, therefore the presence of other individuals seems to have no effects on song.

These males were probably young singers, since some nymphs were observed in the population examined and the first song was emitted by captive males seven days after capture.

Figures

FIGURES 3–8. Cohnia andeana (Hebard, 1924). 3: male lateral view; 4: female lateral view; 5: male pronotum lateral view; 6: male pronotum dorsal view; 7: female pronotum lateral view; 8: female pronotum dorsal view.

FIGURES 9–20. Cohnia andeana (Hebard, 1924). 9: male abdomen tip dorsal; 10: male subgenital plate; 11: male cercus dorsal; 12: male cercus lateral; 13: male cercus tip; 14: female epiproct and cerci; 15: female ovipositor lateral; 16: male abdomen tip dorsal, treated with KOH; 17: female subgenital plate treated with KOH; 18: male titillators dorsal; 19: male titillators lateral; 20: male stridulatory file.

FIGURES 30–31. Cohnia andeana (Hebard, 1924). 30: left tegmina lower side with stridulatory file; 31: particular of middle portion of the stridulatory file.

FIGURES 21–29. 21, 24, 27. Cohnia andeana (Hebard, 1924) female subgenital plate, idem treated with KOH, male abdomen tip dorsal; 22, 25, 28: Dichopetala mexicana Brunner von Wattenwyl, 1878 female subgenital plate, idem treated with KOH, male abdomen tip dorsal; 23, 26, 29: Dichopetala serrifera Rehn & Hebard, 1914 female subgenital plate, idem treated with KOH, male abdomen tip dorsal.

FIGURES 1–2. Cohnia andeana (Hebard, 1924). 1: male from Catamayo; 2: habitat of C. andeana in locality Catamayo (Ecuador).