Species diversity of myrmecofauna (Hymenoptera, Formicidae) on the southern slope of Djurdjura National Park (Northern Algeria)

Species diversity of myrmecofauna (Hymenoptera, Formicidae) on the southern slope of Djurdjura National Park (Northern Algeria). This study was carried out at three study sites in the forests of the southern part of Djurdjura National Park. We found a high variety of ants, with 2,651 individuals belonging to 25 species and three subfamilies, Dolichoderinae, Myrmicinae and Formicinae. Sampling methods used were pitfall traps and hand collection. The dominant subfamily was Formicinae, representing 48 % of individuals collected. Seven species belonged to this subfamily, 31 % of which were Camponotus cruentatus. The second most common species found (18 %) was Tapinoma magnum, an invasive species in many countries. Relative abundance, frequency of occurrence, and diversity varied across the three study sites. Site 1, a black pine forest, had higher species richness (20 species) than site 2, a cedar strip (15 species), and site 3, a mixed holm oak forest (16 species). Our study area has a diverse fauna of ants and distribution of their populations is wide. Data published in GBIF (Doi: 10.15470/htbs0q)

As few studies have been carried out to date in forests areas in Algeria we conducted the present study in the southern part of the Djurdjura National Park to classify Formicidae across three sites that differ in the types of trees therein. The only study conducted previously in this region was that by Cagniant, between 1963 and1966. However, the area has since undergone changes and disturbances due to anthropization. The objective of this study was to update and complete the list of myrmecological diversity in the southern part of Djurdjura National Park (Northern Algeria).

Site description
The National Park of Djurdjura is located in the northern-central part of Algeria (36º 27′ 47″ N, 4º 10′ 41″ E), covering an area of 185 km 2 (Mouslim and Nouel-Kheiter, 2017). The altitude of the Djurdjura chain averages 2,000 meters and has all the typical characteristics of high mountains.
The Park is divided into four sectors. Three are located on the northern slope. Our work was conducted in the fourth sector, located in the southern part and known for the Tikjda mountain pass. This region has a humid, cool bio-climate characterized by four months of drought (June to September) and an estimated average rainfall of 1,258 mm/year. The monthly temperatures range from 18 ºC to 23.4 ºC (Derridj, 1990;Asmani, 1993). The snowfall period may last up to four months in the best years (Derridj, 1990). Being on the southern side of Djurdjura, this sector is directly influenced by hot winds (sirocco).

Ant collection
The study was conducted during spring and summer in March 2016 and July 2017, in accordance with the recommendations of Cagniant (1973) and Barech et al. (2016).
Ants were sampled using two methods, visual detection and direct hand collection (Romero and Jaffe, 1989), and the Barber pots method (Campos et al., 2011). Hand collection was performed when the pots were placed; two researchers actively searched for ants in the vegetation and under stones and rocks for 60'. The ants were then preserved in 70º ethanol.
The Barber pots consisted of metallic containers (7.4 cm diameter × 10.5 cm long), placed at ground level. They were filled to one-third with a solution of water and a drop of liquid dishwashing soap to break the surface tension. For each study site, we selected a 100 m     transect and positioned a pitfall trap every 5 m (20 traps). The pitfall traps were left in place for 48 h. Their contents were then collected using a strainer and placed in Petri dishes where the date and place of collection were recorded. Ants were identified based on the determination keys found in AntWeb and AntCat. Concerning the identification of Tapinoma genus, species level was determined by Pr. Seifert Bernhard, Senckenberg Museum für Naturkunde Görlitz, Am Museum 1, 02826 Görlitz, Germany. The samples are deposited in the Collection Insectarium at the National High School of Agricultural Sciences, Algiers, Algeria.

Data analysis
The results of the myrmecological diversity of this study are expressed by ecological indices: species richness (S), relative abundance (AR), frequency of occurrence (O), Shannon diversity index (H), equitability (E), and Simpson's diversity index and evenness (E) using PAST software (Paleontological STatistics) Version 2.17. Correspondence factor analysis (CFA) was conducted using XLStat software (Copyright © 2017 Addinsoft).

Results
We collected a total of 2,651 individuals belonging to three subfamilies, Dolichodorinae, Myrmicinae and Formicinae, across the three sampled sites in the National Park of Djurdjura (see table 1). The number of ants collected in the pitfall traps (1,499 individuals belonging to 25 species and 13 genera, see dataset published in GBIF, doi: 10.15470/htbs0q) was slightly higher than the number collected by hand (1,152 individuals belonging to 16 species and 11 genera). The most common species found in the Barber pots was Camponotus cruentatus (469 individuals, 31 %) although Tapinoma magnum was the species most commonly caught by the hand method (385 individuals, 32.5 %).
Among the three subfamilies present, Formicinae was the most abundant in the pitfall traps (48 %), followed by Myrmicinae (34 %) and Dolichoderinae (18 %). The most abundant subfamily with the hand collection was Myrmicinae (35 %) followed by Dolichoderinae (33 %) and Formicinae (32 %). Because pitfall traps allowed the collection of a larger numbers of species than hand collection, we based our subsequent analyses on this method. The most common species found in the Barber pots was Camponotus cruentatus (469 individuals: 31 %) whereas Tapinoma magnum was the most common species caught by hand collection (385 individuals: 32 %).
The highest relative abundance was represented by Tapinoma magnum at site 1 and by Camponotus cruentatus at sites 2 and 3. With regard to frequency of occurrence and consistency, Aphaenogaster testaceopilosa was fairly constant in site 1 (40 %) and site 2 (45 %), while in site 3, it was Camponotus cruentatus, which is fairly constant (40 %). Most of other species were rare, very rare, accidental, or incidental (table 2). Table 3 shows the diversity parameters at the three study sites. Wealth and numbers were highest at site 1 (20 species). Dominance tended towards 0 at all three sites, indicting no one species dominated over the others. The Shannon index measures the regularity with which individuals are divided among the taxa present. It revealed values close to two at the three sites, explaining why the southern part of Djurdjura National Park is diversified in ants. The Simpson values (1-D) tended towards one, showing that the diversity was maximal. The flatness values for the three sites were similar.
The distribution of numbers among ant species was not uniform. The graphical representation of the correspondence factor analysis indicates a good distribution of ant species in the three study sites in the southern part of Djurdjura National Park ( fig. 4), with a 100 % contribution rate for both axes 1 and 2. Three groups (A, B and C) emerge from the cloud and each represents the ant species that exist at site 1, 2 and 3, or represent a strong dominance.    Fig. 4. Graphical representation of the correspondence factor analysis of ant species in Djurdjura National Park. Fig. 4. Representación geográfica del análisis de factor de correspondencia en el Parque Nacional de Djurdjura.

Discussion
The southern part of Djurdjura National Park is rich in ants. We identified 25 species in the three selected sites (table 1). Cagniant (1968) worked in 30 forest regions of Algeria and identified 90 species, only 55 % of which were North African. In another study on ant populations in some forest and agricultural environments in Kabylia, Djioua and Sadoudi-Ali Ahmed (2015), 15 species were identified, including 8 species found in a forest at 1,200 m of altitude.
In the southern part of Djurdjura National Park, the subfamily Formicinae dominates in Barber pots with a portion of 48 % and Myrmicinae dominates in direct collection with 35 %. While in the northern part of the same park, precisely in the forests of Tizi Ouzou, Djioua and Sadoudi-Ali Ahmed (2015), Myrmicinae dominates with 57% at all stations. In another type of landscape, in the northeastern Sahara, Chemala et al. (2017) reported the dominance of Myrmicinae (62 %). In Chott El Hodna, Barech et al. (2016), four subfamilies (Dolichoderinae, Formicinae, Myrmicinae and Dorylinae) have been highlighted. Myrmicinae also dominates in this region (58.3 %).
In our study T. magnum represents a little more than a third of the specimens (30.5 %) found at the first site and less than 10 % at the other two sites. This species, previously determined as Tapinoma nigerrimum, is found at up to 1,800 m above sea level with grazing in wetlands (Cagniant, 1968). It is well adapted to survive in cold regions (Noordijk, 2016). This supports its presence in our study area at 1,490 m. In addition, the current name T. magnum of this invasive ant was used by Seifert et al. (2017) and Lenoir and Galkowski (2017).
About half of the ant population are represented by C. cruentatus at site 2 (48.5 %) and site 3 (47.4 %). According to Cagniant (1968), it is mainly found in the holm oak woods of the Tellian Atlas, at an altitude between 800 and 1,200 m. Indeed, the third site of our study is a mixed forest with holm oak. In addition, C. viatica is moderately abundant in all three sites (above 10 %). It is a so-called common species on the edge of forests, cited by Cagniant (1968) in the preliminary list of forest ants in Algeria. In 2009, Cagniant reported that species of the genus Cataglyphis are found in North Africa from the seaside to the Hoggar (the case of the targuia form). It can reach an altitude of 2,800 m and seems to nest in open areas. The A. crocea ant was only found on one occasion at site 1, which explains why it is very rare outside Numidia and Aurès (Cagniant, 1968). On the other hand, A. testaceopilosa is fairly constant in Djurdjura National Park, with a rate varying between 6 and 12 %. Six species are present in all surveyed areas in the northern part of Djurdjura National Park (Djioua and Sadoudi-Ali Ahmed, 2015). These are C. bicolor, A. testaceopilosa, P. pallidula, T. biskrense, T. nigerrimum and M. barbara. These authors also point out that A. testaceopilosa is the most constant ant in the region. In the northeastern Sahara, Chemala et al. (2017) note that the two species M. salomonis obscuriceps and P. pallidula are common in the region. According to Barech et al. (2016), in Chotte El Hodna there are two dominant species, Monomorium sp. and T. biskrense. In our study, M. salomonis, Crematogaser sp., Pheidole sp., T. semilavae, and Temnothorax sp. were poorly represented at all three sites.
The various diversity indices used indicate that the diversity of ants in the southern part of Djurdjura National Park is significant, and that there is a good distribution of ants in the environments surveyed. According to Hölldobler and Wilson (1990), the ant community is dominated by a few species that also contribute to reducing the presence of subordinate or opportunistic ants. And according to Heip et al. (1998), a diversity index summarizes the structure and not the functioning of a community and that regularity is independent of species richness. It is argued that the calculation of diversity or regularity indices should simply serve as descriptors of the community structure and be complemented by information on ecological functioning.