Isophya sicula Orci, Szövényi & Nagy, 2010

Orci, Kirill Márk, Szövényi, Gergely & Nagy, Barnabás, 2010, Isophya sicula sp. n. (Orthoptera: Tettigonioidea), a new, morphologically cryptic bush-cricket species from the Eastern Carpathians (Romania) recognized from its peculiar male calling song, Zootaxa 2627, pp. 57-68 : 59-64

Isophya sicula Orci, Szövényi & Nagy sp. nov.

Type material. Holotype, male (dry, pinned specimen) labelled: “ Isophya sicula , Harghita Bâi (Hargitafürdő), 2009. VI. 17., leg. Orci, K. M. & Szövényi, G.”. Paratypes, 4 males (one of them dry, pinned specimen the others in ethanol), 2 females (one dry, one in ethanol), all of them with the same data as in holotype. All specimens of the type material are deposited in Collection of Small Insect Orders, Hungarian Natural History Museum, Budapest, Hungary. A CD containing a sound recording of the calling song of holotype and paratype males is deposited also in the collection of HNHM.

FIGURE 1. Oscillograms of the male calling song (A, B, D, E) and male female duet of Isophya sicula sp. n. (C, F). Syllable sequences at a larger time scale are shown in A, B, and C; single syllables at a more fine time resolution are presented in D, E, F. Ambient air temperature during the recording was 24.5 o C in the case of A, D; 21.6 o C in B, E; 26.5 o C in C, F.

Male calling song and male-female duet. The male calling song of Isophya sicula sp. n. is a long sequence of syllables (Figs. 1/A, B and Fig. 6/A) produced by tegmino-tegminal stridulation. The duration of a continuous song is rather variable (from a few seconds to several minutes) with apparently accidental termination. A syllable consists of a main impulse series containing typically 1–2 (rarely 3) impulses and 0–1 after-clicks (Figs. 1/D, E and Fig. 6/D). Impulse repetition period in the main impulse series (if there are two or three impulses) is 3–5 ms. Peak amplitude of impulses in the main impulse series is much higher than that of the after-click. Syllables are repeated at an even repetition rate throughout the whole syllable sequence. Syllable repetition period (SRP) proved to be dependent of air temperature (in the range of 21–26 Celsius degrees SRP = 849,75 – 20,26 * T; where T is for air temperature in Celsius degrees, N=11, Pearson product moment correlation between SRP and T was: r = - 0,635, p = 0,036). See Table 1 for basic descriptive statistics on the oscillographic features of the male song. The carrier wave has a wide-band frequency spectrum ( Fig. 2 ) containing detectable components from 15 to 55 kHz and showing an amplitude maximum around 25 kHz. Therefore the male calling song sounds as a rather faint click-series to the unaided human ear and can be heard only from very short distance (1–2 m).

The female response song contains one high amplitude impulse (Fig. 1/F) and occasionally some additional, hardly detectable low-amplitude impulses following or preceding the main one after/by 10–20 ms. Female response can be expected after every syllable of the male (Fig. 1/C) with a response delay of 40–70 ms (60 responses of one female was measured: minimum response delay was 39 ms, maximum 85 ms, 90% of Morphology. Male ( Fig. 3 /A, C, D and Fig.5/C, D): Head with fastigium verticis at base nearly as wide as half of scapus, relatively prolonged slightly tapered frontward; with dorsal groove. Pronotum 3.3–3.7 mm long, lateral carinae nearly parallel in prozona, broken at traverse sulcus, abruptly widen at the middle of length of metazona and becomes nearly parallel in the posterior part of metazona; anterior and posterior edges of pronotum moderately concave; in lateral view, dorsal surface of pronotum moderately concave, raised in metazona; ventral edge of paranota nearly straight; caudal margin of paranota slightly curved and passing into hind margin of pronotum. Maximum height of paranota about half the length of pronotum. Tegmina short and narrow. Visible length of elytra nearly as long as pronotum, approaching or reaching caudal margine of 1st abdominal tergite. Cu2 of tegmen swollen, its length 1/2 of caudal margin of pronotum, not reaching the right margin, right margin of left tegmen forms an obtuse angle at the distal end of Cu2, speculum quadrangular. Stridulatory file 1.6–1.8 mm in length, with 48–60 teeth ( Fig. 4 /A). Hind femur 3.6–4.5 times long as pronotum, without ventral spines. Epiproct 2–2.5 times as wide as long. Cerci 2.0– 2.4 mm long, covered by fine, short hairs, gradually narrow distalwards, distal 1/3 gradually and moderately incurved, apex of cerci rounded, with 1 triangular shaped black denticle. Subgenital plate moderately elongated, reaching the 3/4 length of cerci in dorsal view, narrowed apically with a relatively deep triangular incision and acute lobes on its caudal margin. Coloration green with fine dark spots (Fig. 5/C), in approximately 30 % of the examined specimens with two brick-red bilateral stripes on dorsal side from pronotum to the end of abdomen (Fig. 5/D). Antennae yellowish brown, fastigium greenish brown, disc of pronotum green, lateral carinae with narrow reddish and white stripes. Tegmina brownish with light brown costal field and green margins with yellowish lateral stripe. Legs greenish or brownish with small darker spots.

For descriptive statistics of 9 morphometric characters of males see Table 2.

N Mean Minimum Maximum Std. Dev. Width of head 11 3.54 3.4 3.7 0.102 Length of pronotum 11 3.57 3.3 3.7 0.142 Width of pronotum (caudally) 11 4.14 3.6 4.4 0.269 Length of left elytrum 7 3.89 3.7 4.1 0.135 Width of left elytrum 10 3.12 3 3.3 0.103 Length of stridulatory file 4 1.66 1.6 1.77 0.079 Number of stridulatory pegs 5 53.40 48 60 4.775 Length of hind femur 11 15.77 13.5 17 1.142 Length of cercus 11 2.20 2 2.4 0.1 Female ( Fig. 3 /B, E, F, G and Fig.5/E): Head roughly as in male. Pronotum 3.6–4.3 mm long, with straight lateral carinae, dorsal surface slightly concave, caudally moderately widening from the almost straight frontal margin until its moderately concave caudal margin; without conspicuous sulcus, paranota similar to those of male. Tegmina about third the length of pronotum, approaching or reaching the anterior margin of 1st abdominal tergite, roughly quadrangular, edges more or less rounded. Right tegmen with two fields of stridulatory bristles on its dorsal surface near inner margin as in Fig. 4 /D. Hind femur 3.7–4.5 times as long as pronotum, without ventral spines. Epiproct semicircular. Cerci short, 1.3–1.7 mm long, covered by fine, short hairs, slightly bent, spine-like. Subgenital plate rounded, triangular like. Ovipositor relatively short, 2.1–2.5 times as long as pronotum (8.1–9.3 mm), gradually curving and narrowing distalwards; with 7–10 spines on dorsal margin and 7–9 spines on ventral margin, gonangulum ellipsoid. Coloration of head, body and legs similar to that of male (Fig. 5/E). Tegmina light brownish with yellowish lateral edges. For descriptive statistics of 11 morphometric characters see Table 3 .

Diagnosis. Male song is a long syllable sequence composed of one type of syllable repeated at an even repeatition rate (140–200 syllables per minute at 21–26 C air temperature). Syllables consist of a main impulse-series of 1–2 (3) impulses and 0–1 after-clicks. Fastigium verticis at base half as wide as scapus, elytra reatively short and narrow in male, the length of Cu2 ½ of the width of caudal margin of pronotum, right margin of left elytrum with a rounded obtuse angle at the distal end of Cu2, stridulatory file contains 48– 60 pegs (see Fig. 4 /A). Cerci of male 2.0– 2.4 mm long, gradually narrow distalwards, distal 1/3 gradually and moderately incurved, apex of cerci rounded, with 1 triangular shaped black denticle. Ovipositor 8.1–9.3 mm.

Habitat (Fig. 5/A, B). The type locality of the new species is on the southern slope and plateau-like peak of the mountain Harghita-Ciceu, situated at the southern end of the volcanic mountain range Harghita (inner arch of Eastern Carpathians, Transylavania, Romania). Habitat of this species was found along the edge and in the small clearings of the Piceaetum excelsae forest belt (1350 – 1660 m a.s.l.) and also on the rocky plateaulike peak (1700–1730 m). Characteristic elements of the vegetation structure of the habitat are Juniperus L. and Vaccinium shrubs among the scattered Picea excelsa L. trees and a dense grassy vegetation of 18-40- 60 cm hight among stones and rocks (5–15 % cover). Characteristic species of the Orthoptera assemblage in which Isophya sicula was found were Euthystira brachyptera (Ocskay, 1826) , Myrmeleotettix maculatus (Thunberg, 1815) , Chorthippus pullus (Philippi, 1830) , Miramella Dovnar-Zapolskij, 1932 sp., Decticus verrucivorus (Linnaeus, 1758) .

Etymology. The specific epithet sicula (Latin) refers to the name of a group of local residents in the region of type locality, the Székely people.

FIGURE 5. Photos of the habitat on Mountain Harghita-Ciceu at 1350 m a.s.l in June, 2005 (A) and at 1700 m a.s.l. on 30th July 2004 (B) and specimens of Isophya sicula sp. n. (C, D, E).

Figures

FIGURE 2. Power spectra of the male calling song of Isophya sicula sp. n. (‒), Isophya camptoxypha (−) and Isophya posthumoidalis (…). (FFT size 1024 points, window function Blackmann-Harris)

FIGURE 3. Drawings illustrating the typical eidonomy of Isophya sicula sp. n. male and female. A, male head, pronotum and elytra from above, B, female head, pronotum and elytra from above, C, male pronotum and elytra in profile, D, male external genitalia, E, ovipositor, F, subgenital plate of female, G, cerci and epiproct of female

FIGURE 4. SEM photos of the male stridulatory file of Isophya sicula sp. n. (A), Isophya posthumoidalis (B), Isophya camptoxypha (C) and stridulatory bristles on the dorsal surface of the inner quartile of right elytrum of an Isophya sicula sp. n. female. Scale is the same for A, B, C, but different in D.

Tables

TABLE 1. Descriptive statistics for the basic rhythmic parameters of the male calling song of Isophya sicula sp. n. Abbreviations: SRP: syllable repetition period, DS: duration of syllable, NI: number of impulses in the main impulse series of the syllable, Nac: number of after clicks, Dac: delay of first after click (all duration values are given in milliseconds), T: ambient air temperature during sound-recording, in each character for each specimen mean values of 15 measurements are given.

Specimen	SRP	DS	NI	Nac	Dac	T
1	305.33	1	1	1.07	66.73	24.8
2	372.07	1.13	1	0.6	102.22	24
3	403.53	3.6	1.87	0.93	93.21	23
4	330.27	2.13	1.93	2.07	64.33	22.9
5	332.20	1.8	1.8	-	-	25.7
6	331.53	1.33	1.4	0.67	79.3	25.4
7	353.73	2.4	1.93	1	69.93	24.5
8	374.67	-	-	1	59.46	24.8
9	398.33	-	-	1.47	56.67	24.6
10	324.6	-	-	-	78.75	24.8
11	428.93	3.27	2	1.07	80.47	21.6
Mean	359.56	2.08	1.62	1.10	75.11	24.19
Std. Dev.	39.02	0.97	0.42	0.44	14.61	1.22
Minimum	305.33	1	1	0.6	56.67	21.6
Maximum	428.93	3.6	2	2.07	102.22	25.7