Research Article |
Corresponding author: Klaus-Gerhard Heller ( heller.volleth@t-online.de ) Academic editor: Juliana Chamorro-Rengifo
© 2017 Klaus-Gerhard Heller, Sigfrid Ingrisch, Elżbieta Warchałowska-Śliwa, Chunxiang Liu.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Heller K, Ingrisch S, Warchałowska-Śliwa E, Liu C (2017) The genus Ectadia (Orthoptera: Phaneropteridae: Phaneropterinae) in East Asia: description of a new species, comparison of its complex song and duetting behavior with that of E. fulva and notes on the biology of E. fulva. Journal of Orthoptera Research 26(1): 39-51. https://doi.org/10.3897/jor.26.14548
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The genus Ectadia is an East Asian genus of the tribe Elimaeini (Phaneropterinae) and is known for the complex stridulatory files of its members. The calling song was so far known from only one species, the relatively widespread Ectadia fulva. Here a new species from Yunnan, China, is described, which is morphologically similar to E. fulva except for the stridulatory file. In this character E. fulva deviates strongly from the new species and from all other Ectadia species by its high tooth number. The long lasting song (duration 30 to 60 seconds at 25°C) of the new species is very complex and differs widely from the much shorter song of E. fulva. Its spectral composition changes during stridulation. In the new species the females respond acoustically during gaps in the final part of the male song, whereas in E. fulva they answer typically after the male song. During mating Ectadia fulva males transfer small spermatophores without spermatophylax. All of its six nymphal stages are cryptically colored. In karyotype the new species being the first studied Ectadia species is similar to the related genera Elimaea and Ducetia (all 2n=29 chromosomes in the male).
calling song, stridulatory file, male-female-duet, carrier frequency, Yunnan
In nearly all species of the subfamily Phaneropterinae, males and females communicate by duetting to find a mate (see
Six species are endemic to South China (Yunnan) and northern Vietnam (
In this paper we will describe the species as new and as the sixth member of the genus in Yunnan. In addition, we will present some more data of song and behaviour of E. fulva in comparison.
— Total body length, lateral aspect, refers to the midline length of the insect from fastigium verticis to tip of abdomen including the subgenital plate. In females, the ovipositor is not included in the measurement of the body length. Measurements of ovipositors are taken laterally from tip to base not regarding the curvature.
To obtain the mass data, living animals and spermatophores were weighed to the nearest mg (balance Mettler PM 640).
— IZCAS Insect Collection of Institute of Zoology, Chinese Academy of Sciences, Beijing, China. CH Collectio Heller.
— The male calling song of E. diuturna sp. n. was recorded in the field and in the laboratory using a digital bat detector (Pettersson D1000X) with sampling rates between 100 and 300 kHz. Duets were recorded in stereo using a Sony ECM-121 microphone (frequency response relatively flat up to 30 kHz according to own tests) and an Uher M645 microphone connected to a personal computer through an external soundcard (Transit USB, “M-Audio”; 64-kHz sampling rate). The recordings of Ectadia fulva were made in the laboratory with a Racal store 4-D tape recorder using microphones Brüel and Kjær 4133 and 4135 (frequency response flat up to 40 and 70 kHz respectively)(KGH) and with Kenwood KX880HX and Sony D7 tape recorders using Sennheiser BlackFire541, Sennheiser stereo and AIWA CM-S1 stereo microphones (SI) and digitised years later.
The stridulatory movements of Ectadia fulva were registered by an opto-electronic device (
Song measurements and spectrograms were obtained using Amadeus II and Amadeus Pro (Martin Hairer; http://www.hairersoft.com). Oscillograms of the songs were prepared using Turbolab (Bressner Technology, Germany). All recordings were made at temperatures between 18 and 25 °C. The singers were caged in plastic tubes or gauze cages with microphone fixed or hand-held at distances between 5 (duet) and 80 cm.
For measurements of the stridulatory files, replicas were made using the cellulose nitrate technique described by
— Tettigonioids produce their songs by repeated opening and closing movements of their tegmina. The sound resulting during one cycle of movements is called a syllable, often separatable in opening and closing hemisyllable (
In Ectadia (as in other species), after some time the same or a similar pattern of syllables and pauses is repeated. This grouping, often separated from the next by a silent interval, is called a song unit.
— The sample of a male paratype of Ectadia diuturna sp. n. (CH7661) was used for cytotaxonomic analyses. Gastric caeca were incubated in a hypotonic solution (0.9% sodium citrate), fixed in ethanol - acetic acid (3:1, v/v) and squashed in 45% acetic acid. Cover slips were removed by the dry ice procedure and then preparations were air dried. Constitutive heterochromatin was revealed by the C-banding technique as described by
Ectadia
sp. in
— Holotype male, China, Yunnan, Honghe, Pingbian, Daweishan Forest Reserve, 22°56.55'N, 103°41.43'E, 1700–2100 m a.s.l., 15–17 viii 2013, leg. Liu Chunxiang, #CH7660, in ethanol. Depository IZCAS.
Paratypes 11 males (#CH7659, 61-62), 6 females (#CH7663-5), dried/in ethanol, same data as holotype, all in IZCAS except #CH7659, 61, 64 (in CH). In addition sound recordings of two males, not collected.
— Differs from all species of the genus in proportions of anal (1/3) and basal (2/3) part of the stridulatory file and number (about 100; Table
— Male. General habitus see Fig.
Fastigium verticis narrower than first segment of antennae, sulcate dorsally, not contacting fastigium frontis. Complex eyes approximately round. Pronotum with disc nearly flat, only last quarter elevated; anterior margin slightly concave, posterior margin truncate with small notch in middle; medial carina inconspicuous; transverse sulcus V-shaped; lateral carina weakly developed; lateral lobe of pronotum much longer than high, anterior margin straight, posterior margin obtuse-rounded, ventral margin oblique downward posteriorly, humeral sinus present but inconspicuous.
Prothoracic spiracle large, but mostly covered by a posterior extension of paranotum.
Tegmen shorter than hind wing, posteriorly with long parallel part (Figs
— Body and tegmina green, parts of legs, dorsal side of pronotum and dorsal field of tegmina brown, tegmina with some small brown dots (Figs
— Mostly similar to male except abdominal apex and tegmina (stridulatory organs).
Pronotom with disc nearly flat; ventral and dorsal edge of paranotum parallel.
Right tegmen at posterior edge in basal part with about 9 short cross veins carrying stout spines used to produce the female acoustic response (similar as shown in
— Green except a white mid-line on pronotum and dorsal edges of tegmina (Fig.
>— Thin, flattened, ovoid, typical phaneropterine shape.
— Body: male 14–20, female 17–22; pronotum: male 3.7–4.8, female 3.9–4.2; tegmen: male 26.7–31, female 22–25.3; tegmen width (greatest): male 5.1–6.5, female 4.9–5.1; hind wing: male 33–38; female 26–29.4; post femur: male 20.9–24, female 20.5–23.4; length of ovipositor: 6.5–8.1; width of ovipositor 1.9–2.1, length of egg 4.7–4.8; width of egg 1.6–1.8 (n=12 males, 6 females, partly dried, partly in ethanol).
— Time-amplitude-pattern. In Ectadia diuturna sp. n. one song unit typically lasted about 30 to 60 s (all data for 25°C except otherwise mentioned; up to 80 s in the field at 18°C). It was followed by the next unit after a silent interval as short as some seconds, but also as long as some minutes. The shortest intervals were observed when males and females were in acoustical contact. Each unit contained four phrases each of which consisted of a different combination of micro- and macrosyllables. A simple and clear example is shown in Fig.
The females responded near the end of a song unit (Fig.
— During one song unit, parts with quite different spectral composition were observed. The short, tick-like elements of which phase A and D consisted and which occurred also in phase C, had always a quite similar spectrum. Its peak was situated at about 20 kHz, in the lower half with strong components starting abruptly at about 5 kHz, in the higher half continuously decreasing in power until 40 kHz (Fig.
— The analyzed species is characterized by a male chromosome number 2n=29 and sex determination system X0. All chromosomes are acrocentric and the X chromosome is the largest element in the set. C-banding of mitotic metaphase revealed constitutive heterochromatin blocks (thin C-bands) in the paracentromeric region in most chromosomal elements, with the exception of one small pair of autosomes (thick C-bands). Constitutive heterochromatin polymorphism involving telomeric C-bands was located in the first-sized pair (Fig.
— Common in low bushes around buildings (Fig.
— The name of the new species refers to its long lasting song: diuturna. Latin adjective, meaning long lasting
— Known only from Yunnan, China.
Proportions of distal and basal part and number of teeth in stridulatory file in Ectadia species.
Species | Length of distal part of file | Number of teeth in distal part | Length of basal part of file | Approximate number of teeth in basal part | |
---|---|---|---|---|---|
diuturna | 1/3 | 10 | 2/3 | 90 | this paper |
angusta | 1/4 | 2* | 3/4 | >80* |
|
apicalis | 1/2 | 9 | 1/2 | 60 |
|
fulva | 1/6 | 10 | 5/6 | 250 | this paper |
mistshenkoi | 1/5 | 2*(8) | 4/5 | > 110* |
|
obsolescens | 1/4 | 1–4 | 3/4 | 120–125 |
|
sinuata | 1/2 | 20-25 | 1/2 | many |
|
sulcata | 1/2 | 60 | 1/2 | 20 |
|
Male chromosomes of Ectadia diuturna sp. n. A. C-banded metaphase; B. FISH with 18S rDNA (green) probe in metaphase/anaphase (A – the left) and prometaphase (B – the right). Arrows indicate telomeric located C-bands (A) and cluster of 18S rDNA (B) in the heteromorphic large-sized chromosomes (marked with “1”); X, sex chromosome.
— For the behavioral studies four males and three females (out of series of nine each) were used, all offspring from animals from Thailand, Chiang Mai, Doi Suthep-Pui, 18°48'N, 98°55'E, 1100–1150 m a.s.l., 13.04.1995, ex ovo, bred in lab., leg. S. Ingrisch. Stridulatory files in six males, China, Yunnan Province, Jinping County, Fenshuiling National Nature Reserve, 22.88178768°E, 103.23377388°N, August 2012.
— The species has been sufficiently redescribed by
— Time-amplitude-pattern. The male calling song consisted of song units each lasting about 1.5 s repeated after an interval of about 4 s (Fig.
The female responded immediately after the end of the male impulse series (Fig.
— Both parts of the song unit had a quite similar spectral composition with two peaks (Fig.
Besides the acoustical signals soundless vibratory body movements were observed in both sexes.
— In eight tests, a male (mean body mass 199 ± 16 mg; n=7) and a female (mean body mass 626 ± 71 mg; n = 6) were placed together for mating. Four couples mated with the males transferring only very small spermatophores (1.3 ± 0.6 mg; no data on mating duration available; Fig.
— Postembryonic development occured over six nymphal instars as in many other Phaneropterinae (Fig.
— See Fig.
Male calling song A. and female response B. of Ectadia fulva. Oscillograms of stridulatory movement and song [synchronous registration of left tegmen movement and sound (upper line: upward deflection represents opening, downward closing; lower line: sound)]. Male and female were recorded separately.
Since the revision by
How may these different spectra be produced? From the spectral similarity between E. fulva and the long impulse group in E. diuturna sp. n., one can assume that this two–peak spectrum represents the typical vibration mode of the tegmina when excited during closing. A derived spectrum may result if the teeth are contacted during the opening movement. In several tettigonioid species the sounds produced during opening of the wings have different spectra than during closing (e.g. Metrioptera spp.
Do the different frequencies have any biologically important function? There is no simple answer. The argument that broadbanded songs or songs with different frequencies can give some information about the distance to a signaller (see
Surprisingly, the species which deviates in file morphology most widely from all others - Ectadia fulva - has by far the largest geographic range. One reason could be that this species seems to be adapted to relatively low altitudes. It was found between 250 and 1300 m a.s.l. (
Concerning chromosome evolution, the data presented here are the first available for the genus Ectadia. The basic model karyotype of Phaneropterinae, present also in most tettigoniids, consists of 31 (male) with the X0 (male) sex determination system (for a review see
Our thanks go to Susanne Randolf, Vienna, for the unsuccessful search for the holotype of E. pilosa, and to Andrei Gorochov, St. Petersburg, for information about the files of some Ectadia species. The study was partly funded by the National Natural Science Foundation of China (No. 31572308).