Coenagrion ponticum
Creators: name: Kosterin, Oleg E.
name: Onishko, Vladimir V.
name: Ilyina, Elena V.
name: Chepurnov, Grigory Yu.
name: Blinov, Alexander G.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Odonata
Coenagrionidae
Coenagrion
Coenagrion ponticum

description: Coenagrion ponticum
Agrion ponticum was described by A.N. Bartenef (1929) (the surname spelling as provided therein) in German, next year he reproduced the description in Russian, again using ‘sp. n.’ (Bartenef 1930). The same way and in the same papers he described three other taxa of Odonata from West Caucasus, as considered in detail by Kosterin (2023).
The type series consisted of numerous specimens collected in 1927–1929, from mid-June to early September, by Bartenev himself. Bartenef (1929) characterised the type series origin very briefly and without further comment: “Tuapse, Sotschi, Adler, Pitzunda, Ötshimshiri, Poti, Natanebi, Kobulety, Anfang VI. bis 6.IX. (1926—1928).” The number of specimens was not mentioned. All the mentioned cities/places are at the Black Sea coast of the Caucasus. The later paper in Russian (Bartenef 1930: 65) provides the provenance of the type series in more detail. It is said to originate from 15 localities (sometimes cited with some altered spelling than in 1929): seven currently in Krasnodarskiy Kray (one in Tuapse, one in Sochi and five in the Adler environs), four in Abkhazia (two in Pitsunda, one in Ochemchiri, one at Lake Inktit), one in Samegrelo-Zemo Svaneti (Poti), one in Guria (Natanebi, this actually is a river) and two in Adjara (Kobuleti). The exact numbers of specimens are not provided again, instead there are such annotations as “many specimens”, “medium number of specimens”, “not many specimens”, “few specimens”, “several specimens”, “very few specimens”, “ 1 male (only one male!)”, but the total number of collected specimens seems to be enormous. As for overwhelming majority of Bartenev’s taxa (Medvedev et al. 2013), the type series most probably no longer exists. Since it consisted of a long series of syntypes as the name bearing-type, all the localities enumerated above comprise the vast type locality of the species. It could be narrowed by a neotype designation but we see no necessity in this.
The original (that is published first) description (Bartenef 1929) characterised the range of the new species very briefly. Bartenev reported that “observations show that on the coast of the Black Sea from Tuapse (Gelendzhik?) to Batum are inhabited by only Agrion ponticum (but neither by Agr. pulchellum nor Agr. puella). All previous findings of the latter two species … actually belonged to the species Agr. ponticum ” (translated from German) (Bartenef 1929: 64). “Widespread on the Caucasian coast of the Black Sea. Not present in the mountains.” (Bartenef 1929: 68) (Our finding of the species in Goryachiy Klyuch Ditrict, see above, disproved the latter statement). Bartenef (1930) formulated these statements in somewhat different way—that the species is very common in the Pontic District, comprises there an overwhelming majority of Coenagrion and had been misidentified as either puella or pulchellum in earlier reports. The species was registered up to the Tuapse in the north, while “in Abrau, already Agrion pulchellum flies, but with an inclination towards ponticum ” [sic!] (translated from Russian) (Bartenef 1930: 70).
Both papers (Bartenef 1929; 1930) summarised the characters of the new species in an identical table (see below). The former one (Bartenef 1929) did not discuss the species’ characters beyond the table, while the latter one (Bartenef 1930) claimed the species to be “intermediate in its characters between Agr. puella and Agr. pulchellum ” (Bartenef 1930: 66), and that “it stands most close to Agrion pulchellum, but in the coloration sometimes resembles C. puella. In general, our new species is a true transition between A. puella and A. pulchellum. It likely is a very ancient endemic of the region, at least pre-glacial, and the contemporary Agrion pulchellum and Agrion puella are in genetic kinship with it.” (Bartenef 1930: 70). The latter speculation was not argumented.
Both papers contain a very schematic drawing of the male appendages of C. puella, C. ponticum and C. pulchellum in dorsal view and a more detailed drawing of those of C. ponticum (both papers) or all the three species (Bartenef 1930) in lateral view; that of C. ponticum in (Bartenef 1929) is presented upside down. The drawings fit our specimens quite well.
The characters of C. pulchellum, C. ponticum and C. puella were summarised in an unnumberred comparative table which had 28 lines for males and three lines for females (Bartenef 1929, 1930). Among the 28 male characters, four concerned the pronotum, two concerned the S10 hind margin, nine concerned the appendages and one venation, other 12 characters concerned coloration. Of the three female characters, one concerned the pronotum (“as in male”) and two the coloration. These characters were not evaluated as to their importance and no truly diagnostic ones were indicated. Most of the characters, especially those concerning shape, are described in such fine detail which are no doubt individually variable, could not be reliably diagnostic and were either peculiarities of certain specimens examined or even somewhat imaginary. We find most important the more or less obvious morphological (structural) differences, which we will briefly reformulate below from (Bartenef 1929, 1930) in our terms, with our annotations.
The structural characters of C. ponticum intermediate between those of C. pulchellum and C. puella are:
—Pronotum lateral lobes in both sexes less expressed in C. ponticum than in C. pulchellum, but not as weakly as in C. puella, the central lobe being relatively more expressed as compared to the lateral lobes in C. ponticum than in the two other species. In females, the depressions between the lobes are deep and symmetrical in C. pulchellum (Fig. 7j), less expressed and asymmetrical in C. ponticum (Fig. 7h), scarcely expressed in C. puella (Fig. 7b–g). These pronotum characters are well seen in our female specimens but is not evident in males (see above).
—S10 hind margin dorsal incision in males is deeper than half of its length in C. pulchellum, about the half in C. ponticum and less in C. puella. This is correct but the character is weak as quantitative and without any hiatus (Fig. 2).
—Male cercus length is somewhat less than half of S10 length in C. ponticum, versus somewhat more than half in C. puella and four times as short in C. pulchellum. We find these values incorrect, since in C. puella the cercus may look shorter than half of S10, depending on its position, while reaches 1/3 of the S10 length in C. pulchellum.
—Male cerci contact each other in dorsal view at or just behind S10 hind margin, while only at their bases in C. puella and at the middle of their trunks with their bulges in C. pulchellum. We find this is true for C. puella (Fig. 2d–k) while the point of contact may be similar in C. pulchellum (Fig. 2o–q) and C. ponticum (Fig. 2l–m), at ca proximal ¼ of the trunk, while the actual difference is the shape of the bulge which is a well expressed blunt angle in C. pulchellum (Fig. 2o–q) but gently rounded in C. ponticum (Fig. 2l–m).
—Apex of male cercus trunk moderately convex, while very convex and roundish in C. pulchellum and scarcely convex or straight in C. puellum. We would reformulate that in lateral view, it is bluntly angled in C. ponticum (Fig. 3l–m), narrowly processed in C. pulchellum (Fig. 3o–q) and scarcely convex and gently rounded in C. puella (Fig. 3d–k).
—Male paraprocts scarcely slanting, directed more behind than up, while strongly slanting, directed more up than behind in C. pulchellum and almost horizontal in C. puella. We find that C. puella (Fig. 3d–k) does not differ much from C. ponticum (Fig. 3l–m) in this respect, since the former also may have the paraprocts slanting.
The structural characters of C. ponticum as in C. pulchellum are:
—Male S10 hind margin in lateral view with two bends (one in C. puella). We find those bends scarcely and variably expressed and do not see this difference.
—Cercus process long and straight, reaching paraproct projection (Fig. 4c–d), said to be short (scarcely expanding beyond tubercle) and curved in C. puella (Fig. 4f–k).
The structural characters of C. ponticum as in C. puella are:
—Tubercle present, and said to absent from C. pulchellum, which is not correct: it is well expressed in this species but somewhat obscured by the trunk in dorsal view (Fig. 2o–p). So this character by Bartenev is wrong.
—Male paraproct 1.5–2 times as long as S 10 in lateral and dorsal views, versus as long as in C. pulchellum — but this is a matter of its direction rather than actual length.
—Male paraproct prominence shorter than cercus (as long in C. pulchellum). This character works but the prominence is yet somewhat shorter than the cercus in C. pulchellum as well (Fig. 3o–q).
It is noteworthy that Bartenev’s drawing (Bartenef 1929: abb. 13; 1930: fig. 28) show the paraproct prominence rounded (more like in C. puella but better expressed) rather than processed as in C. pulchellum, as observed in our specimens of C. ponticum (Fig. 3l–m). A similar shape is shown for “Sp. 5” from Azerbaijan associated with C. ponticum by Skvortsov & Snegovaya (2015: fig. 28). This may indicate that populations of C. ponticum still vary in expression of the puella-like and pulchellum-like traits.
Much attention was paid in the original description to fine peculiarities of the black maculation in males, just reflecting its overall expression. We find it best characterised by the extent of the black spot (its main part, not lateral processes) in S3, which, according to Bartenef (1929; 1930), occupies from 1/2 to 5/6 of its length in C. pulchellum, from 1/4 to 4/ 5 in C. ponticum and 1/ 4 in C. puella. Hence its range in C. ponticum, although intermediate with those of C. pulchellum and C. puella, overlaps with both and by no means can be diagnostic.
Importantly, females of C. ponticum have S8 black with only very small blue markings, as in C. puella, while blue with some black spots in all Caucasian specimens of C. pulchellum.
So, our specimens generally fit the original description of C. ponticum except for some characters, and for identification of this species we recommend to use the short character annotation provided above in the annotated list and the key below rather than the big table by Bartenev overloaded with unnecessary details.
While Bartenef (1930) considered C. ponticum ‘a very ancient endemic of the region’, we find it more logical to alternatively suppose that this taxon originated from some Caucasian population which was a product of occasional hybridisation of C. pulchellum and C. puella. If under some condition of the past, unfavourable for Coenarion, both parental species had temporarily vanished from the Black Sea coast while that hybrid population by chance remained the only one in the region, it could later spread as all over the region. The enormous, even intra-population continuous variation of the male black pattern over the whole span between that of both presumed parental species, as well as difference in the paraproct prominence expression between our specimens and those by Bartenef (1929; 1930) and Skvortsov & Snegovaya (2015) may suggest that the puella - and pulchellum -alleles are still co-exist and maybe not yet well mixed in this hybridogenic species.
In view of this supposition it is interesting to note that Bliek (1963) reported and illustrated a presumed male hybrid between C. puella and C. pulchellum found near Tutzing (Bayern, Germany). The illustrated S2 mark (Abb. 2c in loc. cit.) resembles that of C. puella but is thicker, that is inclining towards the C. pulchellum condition. The pronotum hind lobe shape (Abb. 1c) is intermediate between that in the two parental species. Unfortunately, the caudal appendages of the hybrid were illustrated only in the posterior view (Abb. 3c), and the tips of the cercal processes are shown hidden behind the paraproct bases, that is very strange. Anyway, the cerci were shown robust, contacting with their bulges and with scarcely curved processes, that is resembling those of C. pulchellum. The paraprocts were shown as in C. pulchellum but less divergent. In sum, the pronotum lobe of the hybrid is intermediate between the parental species, the S2 markings close to that of C. puella and the appendages resembles those of C. pulchellum. These characteristics are remarkably shared by C. ponticum. The S2 and appendages of the hybrid as depicted by Bliek (1963: Abb. 2c, 3c) could be identifiable as C. ponticum, but the pronotum hind lobe is too sinuous, strictly intermediate between the C. puella and C. pulchellum, while in males of C. ponticum it is closer to C. puella (Fig. 5d, e).
On the other hand, so far there was just a single report of such a hybrid while Lowe et al. (2008) analysed 12 microsatellite loci in C. puella and C. pulchellum from British Isles and revealed no sign of hybridisation between these species. This suggests that hybridisation between the two species is not easy, yet it could take place in the complicated history of the Caucasian fauna.
It should be noted that Russia was missed from the range of C. ponticum in the the IUCN Red List assessment of this species (Boudot 2009), although it comprises a part of its broad type locality, while Armenia was included without a reference. The range is adequately shown in Boudot et al (2021), without Armenia but including the Black Sea coast of Turkey and a locality in North Iran by Schneider et al (2018).
description: Published as part of Kosterin, Oleg E., Onishko, Vladimir V., Ilyina, Elena V., Chepurnov, Grigory Yu. & Blinov, Alexander G., 2024, The genus Coenagrion Kirby, 1890 (Odonata: Coenagrionidae) in the Russian part of the Caucasus, pp. 151-190 in Zootaxa 5471 (2) on pages 183-186, DOI: 10.11646/zootaxa.5471.2.1, http://zenodo.org/record/12189904