Hesperinus imbecillus ( LOEW, 1858 )

Papp, L., 2010, A Study On Hesperinus Walker With Description Of A New Species (Diptera: Hesperinidae), Acta Zoologica Academiae Scientiarum Hungaricae 56 (4), pp. 347-370 : 350-362

publication ID	https://doi.org/ 10.5281/zenodo.12584249
persistent identifier	https://treatment.plazi.org/id/03D887F5-FFBD-0B79-FDC4-FAD2966B58E9
treatment provided by	Felipe
scientific name	Hesperinus imbecillus ( LOEW, 1858 )
status

Treatment

Hesperinus imbecillus ( LOEW, 1858) View in CoL

( Figs 1–43 View Figs 1–3 View Figs 4–11 View Figs 12–17 View Figs 18–21 View Figs 22–29 View Figs 30–35 View Figs 36–39 View Figs 40–43 )

Spodius imbecillus LOEW, 1858 View in CoL was described from “Hungaria (Stein)” (p. 108), which did no specify the locality. However, on p. 108 (3rd par., 3rd line) LOEW fixed clearly Mehádia, as the locality, from where STEIN had the specimen (there is no reason to presume that there was more than one specimen at LOEW’ s disposal). THALHAMMER (1900) gave only Mehádia as its locality in Hungary, so he knew the original (type) locality only. As one can see below, I could not find evidence of the existence and whereabouts of the type specimen during this project.

The earliest reliable occurrence data are in DUDA’ s (1930) monograph in LINDNER’ s series, under the family Bibionidae View in CoL . He published “Im Ung. Nat. Mus. 1 m, 1 f “Szirnka” und 1 m aus Jasenak, 1 m “Mehadia”, 1 m “Verestorony” [central South Carpathians near Turnu Roşu, Romania], 1 m Karst ; im Wien. Mus. mehrere? aus Österreich , Styria inf., [later Yugoslavia, now Slovenia], Illyria Pashtrik (Albanien) ”.

In the series Fauna Hungariae ZILAHI-SEBESS (1960) gave Jasenak [below the Great Kapela Mts, W Croatia], Mehádia [westernmost part of South Carpathians, Romania], Karszt-hegység [ Italy, Slovenia or Croatia!], Szirnka, Verestorony as localities of occurrence in the south parts of the Carpathian Basin. Regretfully, I have to note also here that ZILAHI-SEBESS wrote all those from his memory, at most, based on his file, since all that material had been destroyed in November 1956 ( FÖLDVÁRI & PAPP 2007).

KRIVOSHEINA and MAMAEV (1986) gave its distribution as “Central and South Europe (NL, D, DDR, A, CS, H, AL, R, YU); USSR: SET (Krasnodarskiy kray); mainly in mountain region”. Actually it has never been reported from the Netherlands, and SCHUMANN’ s (1999: 54) item in the Diptera checklist for Germany is without a material base (no voucher specimen has ever been published from the territory of Germany). Their “CS” [ Czechoslovakia)] is a consequence of a misbelieve/misunderstanding that one of the localities listed by DUDA (1930) and/or ZILAHI-SEBESS (1960) would have been a locality in Slovakia. Hungary might have been listed just based on the supposed location of the type locality.

Below I list and characterise the known populations of H. imbecillus by the specimens available for me, according to countries eastwards.

Scales: 0.4 mm for Fig. 1 View Figs 1–3 , 0.2 mm for Figs 2–3 View Figs 1–3

proctiger, dorsal view. Scales: 0.4 mm for Figs 4–6 View Figs 4–11 , 0.2 mm for Figs 8–9, 11 View Figs 4–11 , 0.1 mm for Figs 7, 10 View Figs 4–11

Austria

FRANZ (1989, p. 103) repeated occurrence data of KRIVOSHEINA and MAMAEV (1986). However, he added “In cMW [ Diptera collection of the Naturhistorisches Museum Wien] mehrere Ex. aus “Styr. inf.”, heute Jugoslawien. Mir sind keine Funde aus Österreich bekannt.” Either he or I regarded MOHRIG et al. ’s (1975) wording “ Österreich ” as a publication of a true voucher specimen for Austria. However, at least one of the following three males, which I received from the Naturhistorisches Museum through the courtesy of Dr. PETER SEHNAL, may be accepted as voucher specimen(s) for its occurrence in Austria (southern parts of Austria (Steiermark) seems the most probable area for that):

1 male ( NHM; only hind legs lost): Schiner 1869 – “ Oesterreich ” Alte Sammlung – “imbecillus ” det. Schiner. This cannot be one of the four specimens (coll. H. v. Frauenfeld), which were mentioned by Schiner (1864) on his p. 639, since it was captured after the publication of Fauna Austriaca. This is the largest specimen of H. imbecillus , I have ever seen, body length 7.0 mm, wing length 7.7 mm.

1 male (NHM, an intact specimen): Raibl. 7.74. [blue letters by a typewriter] – “imbecillus ” Bgst [Bergenstamm] – “ Spodius imbecillus Lw ”.

1 male ( NHM; both wings broken off, otherwise well-preserved): Mik. No more label data .

So I think, one must not exclude that even MIK’ s specimen is from a part of the modern Austria.

Italy

I have not managed to get any voucher specimen(s) from Italy. In the case that references would have only been based on the publication of the name “Karst”, its Italian part is the least probable to have been the collection site. Fortunately, MOHRIG et al. (1975) published obviously valid voucher specimens for its occurrence in Italy: “zwei Höhlen in den Venetianischen Voralpen: Causiglio, Valmenera, 28. 6. 1970 (?) und Praderadego, 900 m, 21. 6. 1970 (f)”. They made figures of the male and female palpus and male gonostylus. Unfortunately, the delicacy of those figures does not allow a comparison to ours. We may note here that the occurrence in caves does not mean that the species is cavernicolous. Rather, this was due to aestivation as they found shelter there in the higher summer temperature (cf. PAPP 1982).

Slovenia

The Karst population is probably from a mountain in Slovenia. No specimen was available for me. I found a notice “Karst” in THALHAMMER’ s hand-written list of his collection (the specimen(s) destroyed in the HNHM in 1956). I think that is additional evidence that it was from the Slovenia part. But the specimens from “Styria inf.” (NMW) represent in any case, a population of the species in Slovenia.

Material studied: 1 male ( NHM; mid legs and all right legs lost, apex of right wing broken off, abdominal segments from 6th and genitalia prepared and preserved in a plastic microvial with glycerol): Styria inf., Wotsch , “22. 5. 17”, Zerny. Its body length is 5.54 mm .

Male postabdomen and genitalia ( Figs 4–11 View Figs 4–11 ). Tergite 8 ( Fig. 4 View Figs 4–11 ) quadratic, almost evenly covered by setae. Sternite 8 ( Fig. 5 View Figs 4–11 ) characterised by the comparatively long setae. Epandrium ( Fig. 6 View Figs 4–11 ) rather short, without setae cranially and medially. Gonostylus ( Figs 8–10 View Figs 4–11 ) somewhat emarginate in its broadest view, subapical medial lobe long but narrow, sub-basal process rounded with 4 long setae. Hypandrial setae rather short ( Fig. 11 View Figs 4–11 ), cerci slightly narrower than in the eastern populations; membrane sagittally darkened. Ejaculatory apodeme ( Fig. 7 View Figs 4–11 ) straight with strong and comparatively broad cranial part.

Croatia

The Jasenak population was not available for study by me and the male specimen, which OSWALD DUDA had seen in the collection of the HNHM was destroyed here in 1956.

The Papuk population was formerly unknown. Material studied: 1 male ( HNHM): CROATIA, Papuk Mts above Kutjevo, brook valley with Alnus, 20 Apr 2004, leg. D. Murányi. I prepared its postabdomen with the genitalia ( Figs 12–21 View Figs 12–17 View Figs 18–21 ). Since it was captured only c. 35 km from the Hungarian tively, 0.05 mm for Fig. 17 View Figs 12–17

border, the occurrence of the species also in the Mecsek Mountains (S Transdanubia, Hungary) can be presumed.

Male tergite 8 ( Fig. 12 View Figs 12–17 ) quadrate, evenly covered by setae. Sternite 8 ( Fig. 13 View Figs 12–17 ) rather similar to that of the Styria inf. population. Epandrium ( Fig. 14 View Figs 12–17 ) much different from the above-mentioned populations, quadrate, cranially and medially bare. Gonocoxites ( Fig. 18 View Figs 18–21 ) with very distinct dorso-medial edge in dorsal view, medio-cranial gonocoxal apodemes large. Gonostylus ( Figs 15–17 View Figs 12–17 ) slightly narrowed apically in its widest extension, subapical medial lobe large, sub-basal lobe triangular, the arrangement of setae are different from that of the Slovenian population. Apex of phallus ( Fig. 20 View Figs 18–21 ) rather blunt. Setae on hypoproct weak, in contrast to the rather strong setosity of the cerci ( Fig. 21 View Figs 18–21 ); a thin sagittal area is darker. Ejaculatory apodeme ( Fig. 19 View Figs 18–21 ) probably broken (although I did not see uneven apical edge). If so, cranial part must be massive, broad (actually the broadest among the populations studied).

The “Szirnka” population is most obscure; not even the locality has been identified. My closest match is Srnetica Mts, in Bosnia.

Serbia

In Serbia Dr. DÁVID MURÁNYI and other colleagues captured the first voucher specimen, as follows: 1 female (with minute wing and halter rudiments only): “ SERBIA: Surdulica E 6 km, 750 m, forest, 08. 04. 2006, N42°40.725’ E22°16.399’, Erőss, Fehér, Hunyadi, Murányi” GoogleMaps .

Albania

The population(s) in Albania is unknown to me. However, since it was DUDA (1930) who published about it, we should not question its validity as a Hesperinus species. The specific identity of the Hesperinus specimens in Albania is to be identified on the basis of newly collected material.

Romania

The Mehadia–Orsova population. Material studied: 1 male (Zoologisches Museum, Humboldt Universität zu Berlin): “Orsova, 13. 5. 11.” – [second is a rectangular bluish grey label of 2.5* 2 mm, without writing,? coll. Oldenberg] – [red] Typus – Zool. Mus. Berlin. Its left fore leg and hind legs lost, left wing broken in the middle, flagellomeres wrinkled, so I think this is a freshly emerged fly. Abdominal segment 8 and genitalia are detached, prepared and dissected and now are kept in a plastic microvial with glycerol .

It is a matter of course that the above specimen is not the type of H. imbecillus ( LOEW, 1858) . There are rather numerous specimens in the Berlin Museum, which are mislabelled as such (it was Dr ENDERLEIN who labelled them, as far as I am informed). In any case, this specimen is from the type locality population (distance of Mehadia and Orsova is less than 30 km).

Tergite 8 ( Fig. 22 View Figs 22–29 ) of the Orsova male short, not quadrate. Sternite 8 ( Fig. 23 View Figs 22–29 ) short and broad, without strong cranial emargination, its setae rather long. Epandrium ( Fig. 24 View Figs 22–29 ) medium long with large bare cranial and medial parts. Gonostylus ( Figs 25–27 View Figs 22–29 ) with broad blunt apex in its widest vies, subapical medial lobe short but broad, sub-basal process obviously double and inner lobe larger, outer part with 3 setae only. Ejaculatory apodeme ( Fig. 28 View Figs 22–29 ) with massive broad body and narrowing apical part. Cerci comparatively long and narrow ( Fig. 29 View Figs 22–29 ), also hypoproct with long setae.

0.1 mm for Fig. 19 View Figs 18–21

The “Verestorony”, or Vöröstorony is a defile (pass) between the mountains of Szebeni-havasok and Fogarasi-havasok in the central South Carpathians. Its Hesperinus population is unknown to me since the specimen referred by DUDA (1930) was destroyed in the HNHM in 1956.

The “Tordai-hasadék” population. Tordai-hasadék is in the environs of Petreştii de Jos , Western Transsylvania , Romania. Material studied: 3 males ( HNHM): ROMANIA: Jud. Cluj, Mihai Viteazu , Tordai hasadék, Hesdát-p. [patak, stream] mellett, 450–500 m, 2007. ápr. 30., leg. Papp L. Postabdomen with genitalia of two males have been prepared, figured ( Figs 30–39 View Figs 30–35 View Figs 36–39 ) and kept in plastic microvial with glycerol .

tively, 0.05 mm for Fig. 35 View Figs 30–35

First flagellomere ( Fig. 1 View Figs 1–3 ) with 4 + 1 long setae at distal dorsal apex. Terminal flagellomere is only slightly longer than broad, inner side with 4, outer side with 6 long setae ( Figs 2–3 View Figs 1–3 ). Its wing length is 6.4 mm. I made ten figures of male postabdomen and genitalia ( Figs 30–39 View Figs 30–35 View Figs 36–39 ). Tergite 8 ( Fig. 30 View Figs 30–35 ) 0.7 times as long as its width, rather evenly setose. Sternite 8 ( Fig. 31 View Figs 30–35 ) nearly twice as broad as long, with uneven and emarginated cranial margin. Epandrium ( Fig. 32 View Figs 30–35 ) sub-quadrate with a bare cranial and a conspicuous medial bare area. Gonocoxites ( Fig. 36 View Figs 36–39 ) comparatively broad; medio-cranial gonocoxal apodemes smaller than in the Papuk population. Gonostylus ( Figs 33–35 View Figs 30–35 ) almost evenly broad in its widest view (except for sub-basal process). Subapical medial lobe of gonostylus long broad, its sub-basal process very large with 5 strong setae. Cerci comparatively small ( Fig. 38 View Figs 36–39 ), setae on hypoproct not weaker than those on cerci. No darker (more sclerotised) sagittal membrane was observed. Ejaculatory apodeme ( Fig. 37 View Figs 36–39 ) robust, also apical part long and broad, i.e. it is much different from that of the Orsova population. Phallus comparatively broadly rounded apically ( Fig. 39 View Figs 36–39 , cf. Fig. 20 View Figs 18–21 : Papuk population, and Figs 56–57 View Figs 52–57 : H. graecus ).

Crna Gora

The Durmitor population widens the known distribution to Crna Gora. Material studied: 1 male ( HNHM): [ Montenegro] Zabljak, Mont., 6. VII. 1958 – Podgora 1400 m, leg. Mihályi – “ Hesperinus imbecillus Lw. ” det F. Mihályi. The genitalia of this male specimen were broken off (lost). This fact is much hindering this study. I cannot understand it, since as far as I know, nobody has formerly studied hesperinids in the HNHM .

Bulgaria

The population(s) in Bulgaria was discovered by the excellent late Czech dipterist, Dr J. MARTINOVSKÝ. “We have 11 specimens of H. imbecillus here in collection [ MHNN, Neuchâtel], all originating from Bulgaria (most of them were formerly in the Martinovsky’s collection” (J.-P. HAENNI, in litt.). Dr JEAN-PAUL HAENNI was kind enough to send me a male: 1 male: BULGARIA: 9. 5. 1988. Liljanovo, p. Sandanski (Martinovský) – Hesperinus imbecillus (Loew) m Martinovský det., 1995 – base de données MHNN .

Male genitalia ( Figs 40–43 View Figs 40–43 ). Gonostylus ( Figs 40–42 View Figs 40–43 ) very broad at the level of sub-basal process; subapical medial lobe long but not broad; subbasal process rather large with four strong setae. Ejaculatory apodeme ( Fig. 43 View Figs 40–43 ) robust, also its apical part rather broad.

European Russia (North Caucasus)

The Krasnodarskiy kray population must be most interesting, living so far from the other European populations. I would like to call attention (also for the users of the Fauna Europaea), that Krasnaya Polyana is in Europe, and within the Russian Federation. And it is not in an autonomous republic or autonomous district but within the Russian Republic itself, not far from Sochi.

In the course of this project I have had an opportunity to study a male from that locality. I can corroborate here that it is a separate species. MOHRIG et al. (1975) managed to depict gonostylus, and male palpus of this population. Those have shown definite differences from those of the Austrian and Italian populations. I publish three figures below ( Figs 58–60 View Figs 58–60 ) but the formal description will not be given in this paper (see PAPP & KRIVOSHEINA 2010).

38–39, 0.1 mm for Fig. 37 View Figs 36–39

Discussion. If postabdominal and genital characters of the populations are compared, a strong variation is observable in almost all of the structures. These differences are not clinal or parallel. For me it seems probable that a species with larger range (distributed from the southern Alps to west coast of the Black Sea) during cooler and more wet period(s) of the Glacial Ages was broken into isolated populations in lower mountains of that belt in Europe. An assumption of a strong isolation is deeply underlined by the main feature of this species, the flightless female sex. Although some data hitherto, that the adult male is larger than the female in this species, may suggest an assumption that the male lifts female while in copula, the dispersal of the adults even through that method must be much restricted. The genetic transformations in the isolated populations are likely to be by chance. If I am right, all the isolated populations are on their way to become distinct species. Below I will describe the farthest isolated population in North Greece as a separate species, since also some body features have become different from those of the rest of the populations. The situation with H. imbecillus seems quite similar to that of the Thaumalea species in the middle belt of Europe (all the Alps to the

Scales: 0.2 mm for Figs 40, 42 View Figs 40–43 , 0.1 mm for Figs 41, 43 View Figs 40–43

Carpathians and on the other direction, to the Dinarian and the Balkan Mts). If one analyses genital features against distribution patters of the Thaumalea species groups in WAGNER’ s (2002) excellent book, one will find very closely related species with disjunct ranges, not far distant from each other. The isolation of the Thaumalea species is a consequence of their habits, that the adults do not move away from the water of streamlets not even a metre, they move along the streamlets only (up and down), while larvae are able to move only by the stream. And there are species, like Thaumalea bezzii EDWARDS , where although the differences among populations have also been detected in male genitalia, the species has not been split into nominate species.

The populations differ not only in male genital characters. Variations in size of body and wings, in setosity of the first flagellomere, in the colour of wing veins, in the length and curvature of vein R 4, in the setosity of the distal part of R 4, etc. have been observed also in the course of this project. MOHRIG et al. (1975) also found characters of male and female palpi that they considered usable for separating populations; unfortunately the delicacy of their figures is not convincing. Since I studied dry (pinned) material and I did not make palpal preparations, I did not use palpal features in characterising populations.

I am afraid this is the level of knowledge about the populations of H. imbecillus , which we can reach through studies on outer morphology. Some systematic collections of all populations and molecular methods analysing genetic composition of each population are necessary in order to go deeper into the relationships, incl. decisions on describing nominate species.