Description of a well-known Western Palearctic species of the genus Reptalus Emeljanov 1971 (homoptera, auchenorrhyncha, fulgoroidea, cixiidae) that haS NO valid name

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The genus Replatus with the type species Reptalus quinquecostatus (Dufour 1833) was erected by Emeljanov (1971) in the planthopper family Cixiidae to accommodate species of the tribe Pentastirini (Homoptera, Auchenorrhyncha, Fulgoroidea, Cixiidae) having styles with inner recurrent process.

For a long time many authors under the name R. quinquecostatus meant a widespread planthopper species which is in fact still undecribed. The drawings of the genitalia of this taxon were published by Logvinenko (1975), Holzinger et al. (2003), Emeljanov (2015), etc. However, recent examination of putative type specimens from Dufour’s collection by Webb et al. (2013) showed that this species was misinterpreted at least since Fieber’s work on European Auchenorrhyn- cha (Fieber, 1872) and it is a senior synonym of R. me- lanochaetus (Fieber 1872) sensu Logvinenko (1975) and subsequent authors. As a result, R. quinquecostatus auct. nec Dufour (1833) became nameless. Emeljanov (2020), after studying Fieber’s drawings published by Webb et al. (2013), came to the conclusion that Fieber meant R. artemisiae (Becker 1865) under the name R. quinquecostatus. The first species was very briefly described from the Lower Volga region of Russia (Becker, 1865). However, since the original description with some data on its morphology, R. artemisiae becomes the valid name for R. quinquecostatus auct. nec Dufour (1833) and the type species of the genus Replatus.

According to the original description by Becker (1865), R. artemisiae was collected from Artemisia fragrans Willd. (presently, A. lercheana Weber ex Stechm.) and A. nutans Willd. (Asteraceae) from the subgenus Seriphidium. Our study of male vibrational signals of Cixiidae in the Crimea, in the southern European Russia, Kazakhstan, and Kyrgyzstan revealed that R. artemisiae lives only on Artemisia from the subgenus Seriphidium and occurs only in the Lower Volga and Trans-Volga regions. This species was not found in southeastern Kazakhstan and Kyrgyzstan despite the fact that Artemisia subg. Seriphidium is abundant in the plains and low mountains in these parts.

In the course of these studies, we also found a cryptic species similar to R. artemisiae in external morpho- logy and genitalia structure, but producing signals with a different temporal pattern and feeding on willows (Salix spp.). Apparently, the records of R. quinquecostatus auct. nec Dufour (1833) from many localities outside the Lower Volga region, especially from the territories where Artemisia subg. Seriphidium does not occur (e.g., Nast, 1987), actually refer to this species. Since presently the name R. quinquecostatus is applied to another taxon, this widespread and well-known species does not have a valid name. For this reason, here we provide its description with data on its biology and distribution.

MATERIAL AND METHODS

Small Auchenorrhyncha used for intraspecific communication not air-borne sounds, but vibrational signals transmitted via a solid substrate, i. e. plant stems or leaves on which the insects occur. As shown by ethological experiments, it is the differences in the structure of the calling signals emitted by males to attract conspecific females that constitute the principal precopulatory reproductive barrier in many taxa. Therefore, when differentiating close forms by their signals, one can actually discriminate between biological species based on the very criterion of their reproductive isolation. Thus, acoustic analysis in taxonomy is a useful tool for elucidating the taxonomic status of morphologically similar forms, since the distinct differences in the signal patterns clearly indicate that the taxa under consideration are good species (see the review by Tishechkin (2013)).

Planthopper vibrational signals were recorded by means of portable recording equipment consisting of a piezocrystal gramophone cartridge GZP-311 connected to the microphone input of a cassette recorder Elek- tronika-302 (before 2005), minidisk recorder Sony Walkman MZ-NH900 (2005–2016), or Roland R-05 wave/mp3 recorder (since 2017) via a custom-made matching amplifier. For recording, a stem of the host plant about 10–15 cm in length was attached to the cartridge by a rubber ring with the cartridge needle slightly touching the stem. Then a nylon cage containing a male leafhopper was put on the twig. After some time, the male usually sat on the twig and started singing.

Oscillograms of signals were produced with Cool Edit Pro 2.1 software.

For elements of signal temporal pattern, the following terms are used. Pulse is a brief fragment of signal (or succession of sine waves) with rapid increase and subsequent decrease of amplitude, i.e. separated from similar fragments by amplitude minimums. Fragments with more or less constant temporal pattern consisting of pulses are referred to as syllables. Signal consisting of several syllables is referred to as a phrase.

Digital photographs of male genitalia were obtained with a Micromed 3 LED M microscope equipped with a MIchrome 5 Pro camera (Tucsen). The drawings of male genitalia were made by tracing the outlines of photographs on a glass table lighted from underneath. The map of signal recording localities was produced using free software from www.simplemappr.net.

Morphological terminology follows Emeljanov (2015).

Materials studied are deposited in the collections of the Zoological Museum of M.V. Lomonosov Moscow State University (ZMMU) and the Zoological Institute of Russian Academy of Sciences, St. Petersburg (ZIN).

Reptalus salicinus Tishechkin et Emeljanov sp. n. (Figs 1; 3; 4, 1–9)

Type material. Holotype, ♂: Crimea, environs of Perevalnoe Village, halfway from Simferopol to Alushta, from Salix sp., 16.VI.1997, D. Tishechkin, male calling signals recorded at 28–30^оC (ZIN). Paratypes: 1 ♂, same data, male calling signals recorded at 28–30^оC (ZMMU); 1 ♂, southern European Russia, Volgograd Oblast, the Ilovlya River about 5 km from the mouth, from Salix sp., 8.VI.1996, D. Tishechkin, male calling signals recorded at 25^оC (ZIN); 1 ♂, southeastern Kazakhstan, Urzharsky Region, 27 km south of Taskesken, from Salix sp., 23.VI.2022, D. Tishechkin, male calling signals recorded at 37^оC (ZMMU).

Description. Coloration. Body black, carinae on head and pronotum yellowish, mesonotum entirely black. Forewings transparent with dark veins (fig. 1, 1–2).

 

Fig. 1. Reptalus salicinus sp. n.: 1–2 – habitus dorsally, 3–6 – aedeagus (3, 5 – dorsal view; 4, 6 – ventral view), 7 – anal tube, ventral view; 8 – same, caudal view; 9 – ventro-median process of male genital segment, ventral view; 10 – styles, dorsal view; 11 – right style, ventral and lateral view. 1, 3–4, 10–11 – male from Crimea; 2, 5–8 – male from southeastern Kazakhstan; 9 – male from Volgograd Oblast.

 

Male genitalia. Left paramere of phallotheca rather short, with three processes of different shape (fig. 1, 3–6). Right paramere straight, more or less uniformly tapering distally, with apex usually somewhat bifurca- ted. Anal tube with truncated posterior process bent to right (fig. 1, 7–8). Ventro-median process of pygofer elongated, incisions on back margin of pygofer on each side of it of approximately same width as process (fig. 1, 9). Styles of almost same shape, apical lobe of right style somewhat shorter and wider than of left one (fig. 1, 10–11).

Comparison. In the shape of the genitalia the new species does not differ from R. artemisiae (fig. 2, 1–10). Since the shape of parameres and of the aedeagal processes is quite variable, small differences between individual specimens are the result of intraspecific va- riability and cannot be used to distinguish between R. salicinus sp. n. and R. artemisiae.

 

Fig. 2. Reptalus artemisiae: 1–6 – aedeagus (1, 3, 5 – dorsal view; 2, 4, 6 – ventral view); 7 – anal tube, ventral view; 8 – same, caudal view; 9 – ventro-median process of male genital segment, ventral view; 10 – styles, dorsal view. 1–4, 8, 10 – male from Saratov Oblast; 5–7, 9 – male from Astrakhan Oblast.

 

Male calling signals. Male calling signals of R. salicinus sp. n. from all three localities where the type material was collected were investigated (fig. 3). Calling signal consists of syllables lasting from about 0.7 up to 1.0 s (fig. 4, 1–9). Male produces single syllables following each other with irregular intervals or short sequences of syllables separated by gaps lasting for ca 0.7–1.5 s. Pulse repetition rate in syllable increases with temperature and averages 70 pulses per second at 25^оC, 85–90 pulses per second at 28–30^оC, and 100 pulses per second at 37^оC in our recordings.

 

Fig. 3. Map of planthopper signal recording localities.

 

Fig. 4. Reptalus spp., male calling signal oscillograms: 1–9 – R. salicinus sp. n.; 10–15 – R. artemisiae. Faster oscillograms of the parts of signals indicated as “4”, “6–7”, and “13–15” are given under the same numbers, signal recording localities and temperature during recording are given under the oscillograms.

 

Male calling signals of R. artemisiae from the following localities were investigated:

1. Russia, the Lower Volga region, Saratov Oblast, Dyakovka Village ca 35 km SSW of Krasny Kut Town, from Artemisia subg. Seriphidium on saline soil in the steppe, 9.VII.2004, signals of four males recorded at 22^оC.
2. Russia, the Lower Volga region, Astrakhan Oblast, western shore of the Baskunchak Lake, near Bolshoy Bogdo Mtn., from Artemisia subg. Seriphidium in the semi-desert, 30.VI.2005, signals of one male recorded at 30–31^оC.

In R. artemisiae, male calling signal is a phrase las- ting for about 12–20 s and normally consisting of two shorter syllables followed by one longer syllable (fig. 4, 10–15). The duration of shorter syllables averages 1– 2 s, the duration of the longer syllable is 9–12 s. Pulse repetition rate in syllables is almost the same as in R. salicinus sp. n. and averages 60–70 pulses per second at 22^оC and 70–90 pulses per second at 30–31^оC. Occasionally, the male produces single shorter syllables lasting for 2–5 s.

Thus, the male calling signals of R. salicinus sp. n. and R. artemisiae are distinctly different, which proves that they are different biological species.

Biology. All studied specimens of R. salici- nus sp. n. were collected from willows (Salix spp.), whereas R. artemisiae was found only on Artemisia subg. Seriphidium.

Willows, with rare exceptions, grow in humid ha- bitats, while Artemisia subg. Seriphidium occur in the steppe and desert zones and often grow on saline soils. Therefore, it can be safely assumed that R. salicinus sp. n. and R. artemisiae are almost always spatially and, as a consequence, reproductively isolated not only due to differences in the signal patterns, but also due to different host specializations.

Distribution. Judging by the findings, confirmed by the calling signal analysis, the range of R. salicinus sp. n. includes southern European Russia and Kazakhstan (fig. 3). The record of R. quinquecostatus from willows in Germany by Biedermann and Niedringhaus (2009) also, apparently, belongs to R. salicinus sp. n. The records of R. quinquecostatus from other plants (e. g., Logvinenko (1975)) may refer to another species. In particular, Holzinger et al. (2003) previously suggested that R. quinquecostatus auct. nec Dufour (1833) may actually include several closely related species.

Reptalus artemisiae is known only from the steppes and semi-deserts of the Lower Volga and Trans-Volga regions; evidently, records of R. quinquecostatus from the saline lands of western Kazakhstan by Mityaev (2002) also refer to this species. It should be noted, that so far R. artemisiae was not found on Artemisia subg. Seriphidium in similar biotopes in southern and southeastern Kazakhstan and Kyrgyzstan.

Ethymology. The name of the species derives from the name of its host plant, Salix.

Remarks. We failed to find morphological traits for distinguishing between R. salicinus sp. n. and R. artemisiae. However, since these species are associated with different plants that differ distinctly in biotopic preferences, it is sufficient to have data on the biotope and sometimes only on the locality, to identify a species.

Due to the fact that the specimens, based on which Becker (1865) described the species Flata artemisiae Becker 1865 = R. artemisiae (Becker 1865), were not found, and this name was applied to the cryptic species indistinguishable in morphological traits, we consider it necessary, in accordance with Article 75 of ICZN, to designate the male which calling signals were recorded and which was collected from the same host plant in the locality nearest to the original collection site (Sarepta = Krasnoarmeysk, now part of the city of Volgograd) as the neotype of F. artemisiae Becker 1865.

Neotype: ♂, Russia, Astrakhan Oblast, western shore of the Baskunchak Lake, near Bolshoy Bogdo Mtn., from Artemisia subg. Seriphidium in the semi-desert, 30.VI.2005, deposited in ZIN (fig. 2, 5–7, 9; 4, 12, 15).

ACKNOWLEDGEMENTS

We express our sincere thanks to Dr. Vladimir Gnezdilov (ZIN) for reading the manuscript and providing critical comments and suggestions. The first author is most grateful to Asek Abdykulov (Kara-Balty, Kyrgyzstan) and to his daughter Asel Lee (Kara-Oy, Kazakhstan) for invaluable help and hospitality during the visit to Central Asia in 2022.

FUNDING

Investigations of D. Yu. Tishechkin were carried out as a part of the Scientific Project of the State Order of the Government of Russian Federation to Lomonosov Moscow State University No. 121032300063-3, the study of A.F. Emeljanov is performed in the framework of the Russian State Research project № 122031100272-3.

ETHICS APPROVAL AND CONSENT TO PARTICIPATE

This work does not contain any studies involving human and animal subjects.

CONFLICT OF INTEREST

The authors of this work declare that they have no conflicts of interest.

About the authors

D. Yu. Tishechkin

M. V. Lomonosov Moscow State University

Author for correspondence.
Email: macropsis@yandex.ru

Faculty of Biology

Russian Federation, Vorobyevy Gory, Moscow, 119234

A. F. Emeljanov

Zoological Institute, Russian Academy of Sciences

Email: alexandr.emeljanov@zin.ru
Russian Federation, 1 Universitetskaya Emb., Saint Petersburg, 199034

References

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