Biodiversity Data Journal :
Taxonomic Paper
|
Corresponding author: Albena Lapeva-Gjonova (gjonova@gmail.com)
Academic editor: Marek Borowiec
Received: 10 Mar 2021 | Accepted: 02 May 2021 | Published: 21 May 2021
© 2021 Albena Lapeva-Gjonova, Alexander Radchenko
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:
Lapeva-Gjonova A, Radchenko AG (2021) Ant genus Strongylognathus (Hymenoptera, Formicidae) in Bulgaria: a preliminary review. Biodiversity Data Journal 9: e65742. https://doi.org/10.3897/BDJ.9.e65742
|
Strongylognathus Mayr, 1853 is a Palaearctic genus, comprising 25 ant species and one subspecies, all permanent social parasites, infesting colonies of various species of Tetramorium Mayr, 1855. They have patchy distribution throughout their areas and most of them are very rare and listed as vulnerable.
The taxonomy of the Strongylognathus huberi group needs thorough revision and the results presented below can be considered as preliminary.
Four species of the socially parasitic ant genus Strongylognathus (S. karawajewi Pisarski, 1966, S. huberi dalmaticus Baroni Urbani, 1969, S. afer Emery, 1884 and S. italicus Finzi, 1924) are recorded for the first time from Bulgaria and, together with the previously-known S. testaceus and S. bulgaricus stat. rev., their total number reaches six. The taxonomic position and geographic distribution of all species are discussed and a Key for their identification, based on worker caste, is compiled.
ants, Balkans, fauna, social parasites, taxonomy, Strongylognathus karawajewi, S. huberi dalmaticus, S. afer, S. italicus, new records, key
Strongylognathus Mayr, 1853 is a Palaearctic genus, comprising 25 ant species and one subspecies distributed from north-west Africa to Japan, but with a gap in east Siberia, Mongolia and Russian Far East (
Strongylognathus is divided into two species-groups: the testaceus- and huberi-group (
The testaceus-species group contains four species – S. testaceus (Schenck, 1852), S. karawajewi Pisarski, 1966, S. potanini Radchenko, 1995 and S. tylonus Wei, Xu & He, 2001. The first two species are distributed in the West Palaearctic from Atlantic coasts to middle Asia and west Siberia, but the latter ones are known from China (
The majority of the members from the huberi-group (19 species and one subspecies) are distributed in the Mediterranean Region, Southern and Central Europe, south of east Europe, Caucasus, Anatolia, Near and Middle East, Turkmenistan, Iran and Afghanistan and only two species are known from China, Korea and Japan (
All Strongylognathus species are permanent social parasites, infesting colonies of various species of Tetramorium Mayr, 1855. Many species of the huberi-group are dulotic, engage slave raids and attack colonies of Tetramorium, retrieving their brood. In contrast, species of the testaceus species-group appear to be queen-tolerant parasites and do not engage in slave raids and co-exist with the host queen, which produces only worker caste (
So far, two Strongylognathus species have been recorded from Bulgaria – S. testaceus and S. bulgaricus Pisarski, 1966 (
Below, we record, for the first time, four Strongylognathus species from Bulgaria: S. karawajewi, S. huberi dalmaticus Baroni Urbani, 1969, S. afer Emery, 1884 and S. italicus Finzi, 1924. Thereby, the currently-known Strongylognathus species to the country has increased to six. Their taxonomic position and a Key for the identification of Bulgarian Strongylognathus species, based on the worker caste, are provided.
The taxonomy of the Strongylognathus huberi group needs thorough revision and it is simply impossible to unambiguously identify most of the West Palaearctic species and the results presented below can be considered as preliminary.
Strongylognathus species were collected during a myrmecological survey in Bulgaria by the first co-author of the paper (ALG). In recent years, special attention has been paid to the southern regions of the country (Eastern Rhodopes, Thracian plain, Strandzha, Slavyanka and Maleshevska Mountains), where the ant fauna is most diverse, but has not been properly investigated yet in detail. Collected material is preserved at the Biological Faculty, University of Sofia, Bulgaria (BFUS). The examined type specimens of S. karawajewi Pisarski, 1966 are preserved in the collections of the Schmalhausen Institute of Zoology NAS of Ukraine, Kiev (SIZK) and the Museum and Institute of Zoology PAS, Warsaw (MIIZ). All Tetramorium nests, infested by Strongylognathus, were located in the ground under stones. Photos of some collection sites are shown in Fig.
Photos of some collection sites: a – Thracian plain, Besaparski hills, near Ognyanovo vill. (habitat of Strongylognathus karawajewi); b – Stara planina, near Karnare vill. (habitat of S. karawajewi); c – Eastern Rhodopes, near Chernichino vill. (habitat of S. karawajewi and S. italicus); d – Eastern Rhodopes, near Gaberovo vill. (habitat of S. karawajewi and S. afer).
Six measurements of specimens (accurate to 0.01 mm) were taken and used to calculate four indices:
Eciton testaceum Schenck, 1852: 117, w, q, Germany.
Strongylognathus testaceus:
Strongylognathus testaceus appears to be the most common species of this genus, it widely spreading in Central and Southern Europe, southern part of east Europe, the Caucasus, Anatolia, south of west Siberia and northern Kazakhstan (
Strongylognathus testaceus has long been known as a social parasite of Tetramorium caespitum (Linnaeus, 1758), but was recently found in the nests of T. alpestre Steiner, Schlick-Steiner & Seifert, 2010 and T. impurum (Foerster, 1850) (
Strongylognathus karawajewi Pisarski, 1966: 521, w, Ukraine;
Vulnerable D2 ver. 2.3 (
Strongylognathus karawajewi was described, based on workers from the southern coast of Crimea (vill. Magarach, now Otradnoye near Yalta, material from the collection of W. A. Karawajew, ZISK) by
Strongylognathus karawajewi has been known as a social parasite of T. caespitum (s. l.), T. sulcinode Santschi, 1927, T. inerme Mayr, 1877, T. ferox Ruzsky, 1903 and T. feroxoide Dlussky & Zabelin, 1985 (
This species inhabits extremely xerothermic sites in Bulgaria at an altitude below 660 m. One of them is located in the Besaparski Hills in the Thracian plain - low calcareous ridges with typical steppe-like vegetation (Fig.
Two species of the testaceus species-group (S. testaceus and S. karawajewi) are known from the West Palaearctic and their separation is usually straightforward. The head dorsum in workers of S. karawajewi is usually completely smooth and shiny, fine striation may be present only on its sides, while at least frons and genae, but often whole head dorsum, is with well developed longitudinal rugosity in S. testaceus. The sculpture on the sides of mesosoma in males of S. karawajewi is strongly reduced, but it is at least partly coarsely rugulose and shagreened in S. testaceus (
Strongylognathus huberi subsp. rehbinderi var. bulgarica Viehmeyer, 1922: 211, w, q, m, Bulgaria (unavailable name).
Strongylognathus rehbinderi subsp. bulgaricus:
Strongylognathus bulgaricus:
Senior synonym of Strongylognathus kratochvili Šilhavý, 1937: 5, w, q, Czech Republic:
S. bulgaricus is revived from synonymy with S. kratochvili and synonymised with Strongylognathus christophi Emery, 1889: 439, q, Russia:
Vulnerable D2 ver. 2.3 (
The previous records of the species in Bulgaria are from northern Bulgaria – Veliko Tarnovo, Preobrazhenski Monastery (10 km from Veliko Tarnovo), Dryanovo, Veliki Preslav and one (Silistar) is on the southern Black Sea coast (
Recently,
On the other hand, S. bulgaricus and S. kratochvili are very similar to each other in many subjective features (e.g. sculpture of the head and mesosoma, pilosity, shape of the propodeal dents etc.), but S. kratochvili differs from S. bulgaricus by noticeably larger body size (it is one of the largest Strongylognathus species, as Šilhavý has already emphasised). We agree with the proposed separation of these species (see
Strongylognathus dalmaticus Baroni Urbani, 1969: 154, w, Croatia;
Strongylognathus huberi dalmaticus:
Vulnerable D2 ver. 2.3 (
Strongylognathus dalmaticus was described by
It is no coincidence that this species is found in the Eastern Rhodopes, where the influence of the warmer Mediterranean climate is stronger and xerothermic plant communities are present. The collecting site near the village of Meden Buk is located in the valley of the Byala Reka River near the Greek border and it is one of the southernmost points of Bulgaria.
Strongylognathus huberi subsp. italica Finzi, 1924a: 14, q, Italy (Ils. Elba);
Strongylognathus italicus:
As senior synonym of Strongylognathus alboini
Vulnerable D2 ver. 2.3 (
In the same year,
Strongylognathus italicus differs from other Bulgarian species of the huberi-group by the coarser sculpture on the head dorsum and somewhat longer antennal scape. In Bulgaria, it was found only once on a southern slope of xerothermic grassland situated in an oak forest (Fig.
Strongylognathus afer Emery, 1884: 380, q, Algeria;
Vulnerable D2 ver. 2.3 (
Strongylognathus afer was described by
One nest sample of workers, together with the host species T. hungaricum, was collected in the Eastern Rhodopes on the border of light oak forest and a pasture with a southern exposure (Fig. 4) at an altitude about 550 m. Collected workers morphologically fit well with the main characteristic features of S. afer, but are even smaller than the specimens from Algeria and Morocco, as well as workers of S. minutus Radchenko, 1991 and, apparently, are the smallest known workers of the huberi species-group (compare Table
Measurements (in mm) and indices of the investigated species of Strongylognathus huberi-group. Measured material: S. bulgaricus: Eastern Rhodopes, Dolna kula (17 workers); Kardzhali (2 workers); S. huberi dalmaticus: Eastern Rhodopes, Meden Buk; S. italicus: Eastern Rhodopes, near Chernichino vill.; S. afer: Eastern Rhodopes, Gaberovo vill.
S. bulgaricus (n = 19) | S. huberi dalmaticus (n = 15) | S. italicus (n = 20) | S. afer (n = 17) | |||||
mean | min-max | mean | min-max | mean | min-max | mean | min-max | |
Measurements | ||||||||
HL |
0.774 |
0.719-0.825 |
0.807 |
0.754-0.842 |
0.811 |
0.754-0.912 |
0.693 |
0.632-0.719 |
HW |
0.669 |
0.614-0.737 |
0.698 |
0.614-0.737 |
0.736 |
0.684-0.842 |
0.594 |
0.544-0.623 |
SL |
0.511 |
0.474-0.544 |
0.543 |
0.509-0.561 |
0.587 |
0.544-0.649 |
0.468 |
0.421-0.491 |
ML |
0.925 |
0.860-1.000 |
1.002 |
0.895-1.070 |
1.012 |
0.912-1.175 |
0.821 |
0.711-0.860 |
PW |
0.200 |
0.175-0.237 |
0.228 |
0.193-0.246 |
0.227 |
0.193-0.263 |
0.179 |
0.158-0.193 |
PPW |
0.270 |
0.246-0.298 |
0.299 |
0.263-0.333 |
0.306 |
0.281-0.351 |
0.227 |
0.211-0.246 |
Indices | ||||||||
CI |
1.157 |
1.119-1.200 |
1.158 |
1.095-1.228 |
1.101 |
1.069-1.129 |
1.166 |
1.141-1.206 |
SI |
0.660 |
0.636-0.708 |
0.673 |
0.638-0.695 |
0.725 |
0.615-0.750 |
0.675 |
0.650-0.699 |
PI |
0.742 |
0.687-0.843 |
0.761 |
0.722-0.801 |
0.741 |
0.685-0.795 |
0.788 |
0.749-0.846 |
PPI |
0.403 |
0.381-0.425 |
0.428 |
0.405-0.452 |
0.416 |
0.395-0.445 |
0.382 |
0.354-0.400 |
Key for identification of Strongylognathus species of Bulgaria (workers) |
||
1 | Occipital margin of head strongly concave (seen from above), posterio-lateral corners of head strongly prominent (seen from sides) (Fig. |
2 |
– | Occipital margin of head straight or, at most, very shallowly concave (seen from above), posterio-lateral corners of head rounded and not prominent (seen from sides) (Fig. |
3 |
2 | Whole head dorsum usually smooth and shiny, fine striation may be present only on the sides of head dorsum (Fig. |
S. karawajewi |
– | At least frons and genae (often whole head dorsum) with well developed longitudinal rugosity (Fig. |
S . testaceus |
3 | Propodeum without dents, at most with blunt tubercles (Fig. |
S. afer |
– | Propodeum with at least small sharp dents (Fig. |
4 |
4 | Head sculpture coarser, longitudinal rugulae on lateral parts of head dorsum curve inside posteriorly and surround occipital margin (Fig. |
S. italicus |
– | Head sculpture weaker, longitudinal rugulae on lateral parts of head dorsum do not curve inside posteriorly, occipital margin smooth (Fig. |
5 |
5 | Propodeal dents directed almost upwards; petiolar node dorsum narrowly rounded (Fig. |
S. bulgaricus |
– | Propodeal spines directed upwards and backwards at an angle of ca. 45°; petiolar node dorsum widely rounded (Fig. |
S. huberi dalmaticus |
The record of S. karawajewi in Bulgaria is quite consistent with the zoogeographic data and today represents the westernmost edge of the range of this East Tethyan species. At first glance, it may seem that the finds of the north-west African or west Mediterranean species (e.g. S. afer and S. italicus) in Bulgaria are unlikely, but this is not entirely true. As mentioned above, at present the taxonomic situation in the huberi species-group, especially in the West Palaearctic (i.e. west of Yenisei River and the Tien Shan Mts.; see
Although S. afer is formally recorded only from the north-western Africa and its relationships with three other Iberian and Italian species is not fully resolved, their conspecificity appears quite possible.
Previously,
In addition, it should be emphasised that Strongylognathus fauna is very poorly understood in the former Yugoslavian countries and this territory appears a “blind spot” between Italy on the west and Bulgaria in the east. Thus (excluding S. alboini and S. huberi dalmaticus with the type localities in Slovenia and Croatia), only one more species, the common S. testaceus, was recorded from Serbia, Croatia and Slovenia (
We are sincerely grateful to Prof. Lech Borowiec (Wroclaw, Poland) for verification of Strongylognathus huberi dalmaticus identification. We also thank Petr Werner (Prague, Czech Republic) for the specimens provided for this study and reviewers of the manuscript for their valuable comments. This work has been carried out in the framework of the National Science Programme "Environmental Protection and Reduction of Risks of Adverse Events and Natural Disasters", approved by the Resolution of the Council of Ministers No 577/17.08.2018 and supported by the Ministry of Education and Science (MES) of Bulgaria (Agreement No Д01-363/17.12.2020) (for A. Lapeva-Gjonova) and supported by a Grant NRFU (Ukraine) No. 2020/02/0369 (for A. G. Radchenko).