Trithemis kirbyi (Sélys, 1891)

Mairif, Mohamed, Bendifallah, Leila & Doumandji, Salaheddine, 2023, Diversity of Odonates (Odonata, Anisoptera & Zygoptera) in the Theniet El Had National Park-North West of Algeria, Journal of Insect Biodiversity and Systematics 9 (1), pp. 155-182 : 166-170

Trithemis kirbyi (Sélys, 1891) ( Fig. 6D)

In general, this species is expanding rapidly ( Bailleux et al., 2017), but it shows a very restricted distribution in the national park. It is found in low numbers (03 individuals) in the only forest reservoir on the southern slope ( Fig. 6E), which represents the lowest water body (1287 m) in the study area, observations are detailed as follows: RSA, 15.V.2017, 1♂; 15.VI.2017, 1♂ 1♀.

Flight phenology of odonates ( Fig. 7). The flight period of odonates was very variable according to the species, it is generally less than one year, the flight periods indicated in Fig. 7 correspond to the observations recorded in the national park during the study period, in comparison with the reference flight periods for Algeria taken from the synthesis of Samraoui and Menaï (1999). Concerning the species occasionally present in the national park, we note for Calopteryx haemorrhoidalis , a very short flight period (one month) compared to six months of reference. This is probably due to the increase in temperature where most of the watercourses stop flowing. For Sympetrum sinaiticum and despite its short flight period (one month), we recorded a perfect synchronisation of its flight period with the reference period. As for Trithemis kirbyi , it presents a remarkable precocity of the emergence of two months compared to the reference period, where we could observe the first individual in May. The appearance of Orthetrum nitidinerve in our study area is late, where we encountered two individuals in September, while the reference period spans two months (July and August). The same is true for Ischnura pumilio , which was recorded with a one-month delay in its predicted emergence period. For the species potentially or moderately present in the park, the variations of the flight period compared to the reference period is practically insignificant for the majority of the species which remain with some exceptions; we note for Anax parthenope , Orthetrum coerulescens a total similarity of emergence with the reference periods. For Orthetrum cancellatum , Orthetrum chrysostigma , Sympetrum fonscolombii and Sympetrum striolatum , the onset of their emergence is identical to that of the reference periods, but with a flight delay of one to two months compared to the references, whereas Aeshna mixta , Anax ephippiger , Trithemis annulata and Erythromma lindenii emerged one month later than expected. Erythromma lindenii has a flight period with gaps in between; this is due to the lack of observations of this zygopteran. Chalcolestes viridis shows a remarkable delay in the emergence of three months with four months of flight delay. For Crocothemis erythraea and Symperrum meridionale , the flight variations compared to the reference are significant (2/9 months and 3/7 months respectively). It is worth mentioning that during our study, Sympetrum striolatum shows the longest flight period (10 months) while Sympetrum sinaiticum , Orthetrum nitidinerve and Calopteryx haemorrhoidalis show the shortest flight period (one month). The two months of January and February were without any odonate observations.

Chorological study of the odonates of Theniet El Had National Park ( Fig. 8). In this section, we study the bio-geographical origins of the odonatological procession of the national park from the synthesis of ( Jacquemin & Boudot, 1999, Boudot & Kalkman, 2015). The 18 species of odonates recorded in the Theniet El Had National Park belong to two different chorological groups, adominating group of Palaearctic origin with 61%, it includes a set of species present in the old world and becoming rare or disappearing in the intertropical zone. 46% of the Palaearctic group are species with their centre of gravity in the Mediterranean basin, They form the Mediterranean odonotological subgroup ( Fig. 9) to which Erythromma lindenii belongs, which has a holo-Mediterranean extension with an Atlantic expansion, plus Anax parthenope and Sympetrum meridionale as holo-Mediterranean species with an eastern expansion that extends well into the East.

Calopteryx haemorrhoidalis belongs to the West Mediterranean species which have a centre of gravity strictly positioned on the Western Mediterranean basin with its islands, although they can also extend to the Atlantic side of Europe. Orthetrum nitidinerve is an Iberian-Maghrebian species which is part of the West Mediterranean lebillules, occupying both North-West Africa and the Iberian peninsula. This allows us to deduce the predominance of taxa with a Holo-Mediterranean distribution with eastern expansion with 40%, the three remaining categories represent 1/5 for each. The West Mediterranean species in the broad sense include the Ibero-Maghrebian group, however, due to the limited distribution of the latter compared to the West Mediterranean species in the strict sense, it was useful to treat them separately. In the Laou catchment area in Morocco ( El Haissoufi et al., 2008) and in the Bejaia region in Algeria ( Chelli & Moulaï, 2019), the same findings are raised regarding the superiority of Mediterranean species. The other sub-groups of the Palaearctic share the other half, where the Euro- Siberian sub-group, consisting of species widely distributed from Middle Europe to Siberia and not concentrated in the Mediterranean, namely Aeshna mixta and Orthetrum cancellatum , represents 18% of the odonatological richness of the park, while the West Palaearctic species, which are limited to the western part of the Palaearctic domain, namely Chalcolestes viridis , Orthetrum coerulescens anceps and Sympetrum striolatum , represent 27%. The sub-Mediterranean sub-group represents 09%, and groups together species with a clear Mediterranean affinity, making the transition to the more strictly Mediterranean species, in our case Ischnura pumilio is the only species with this extension. The second group gathers taxa with a wide distribution, with 39% of the odonatological richness of the national park. It forms two sub-groups: the Afro-tropical species occupy 86% of this category and largely exceed the other sub-group. They are essentially African, and become abundant in the South of the Sahara, the Near East, Asia and even, sometimes, reach the South of Europe.

Their existence in the park is represented by Anax ephippiger , Orthetrum chrysostigma , Trithemis annulata , Trithemis kirbyi , Sympetrum fonscolombii and Crocothemis erythraea . The second sub-group contains the North African species with European expansion whose distribution is very wide and includes all of North Africa and a large part of Europe, the only species that represents this sub-group in our study is Sympetrum sinaiticum , species with a Saharan distribution, which reach the North of Spain and the South of Italy representing 14% of the odonatological wealth of the group.

Statistical study of the results. The hierarchical ascending classification (ACH) and principal component analysis (PCA) of the study sites showed a fairly apparent relationship between the altitude of the water bodies and the distribution of odonates in the park, but the exposure effect did not appear in the clustering. For the water bodies, the ACH classified them into two distinct groups ( Fig. 10). Group A contains the four temporary pools at medium altitudes, which contain the majority of the odonates found in the park and are dominated by Anisoptera .

The four sites that remain at high altitudes form a second group B and contain a smaller number of odonates than the first, and are dominated by Anisoptera . In terms of species, the ACH indicates the presence of four groups in terms of numbers and observation sites, with Sympetrum striolatum alone forming one group due to its presence in all the study sites. The second group is composed of four species Aeshna mixta , Anax ephippiger , Sympetrum fonscolombii and Orthetrum coerulescens ; the third group is the most diversified, it includes nine species, Symperrum meridionale , Orthetrum chrysostigma , Anax parthenope , Trithemis annulata , Erythromma lindenii , Calopteryx haemorrhoidalis , Orthetrum cancellatum , Crocothemis erythraea and Ischnura pumilio . It should be noted that the last four species are recorded in less than half of the study sites. The fourth group includes rare species that are recorded in a single study site regardless of their number, namely Chalcolestes viridis , Orthetrum nitidinerve , Trithemis kirbyi and Sympetrum sinaiticum , the latter of which is the least represented in the study area, with a total of one (1) individual at a single site ( Fig. 11).

Composition and structure of odonate populations in the National Park. The first finding of this index study is the inequitable distribution of individuals between the different taxa and the different sites. The Sidi Abdoune reservoir and ponds RPP, DMPI and ATP, where more species are found, are the localities with the best structured and most stable odonatological populations. This is probably due to the open and sunny nature of these locations, which have provided ideal conditions for the establishment of odonates. The values of the Shannon diversity index (H') vary between 1.12 and 2.55. These values reflect the considerable diversity of species found in the different ponds studied. Ponds RPP, ATP and SAHR are characterised by diverse and balanced populations, the least diverse population is found in pond EGP, and the rest of the ponds are characterised by rather moderately balanced populations ( Table 3). Values of the evenness index (E) vary between 0.62 and 0.93, with the highest value (0.93) recorded in pools DMPII and ATP, followed by the hillside reservoir SAHR (0.92), then pool ERP (0.9). Ponds RPP, DMPI and BP have values close to 0.87 and 0.86, these values are close to 1, therefore the numbers of taxa sampled tend to be in equilibrium between them. The lowest value of equitability is for pond EGP (0.62), which clearly explains the predominance of certain taxa.