Aphanius saourensis, José L. Blanco, Tomas Hrbek & Ignacio Doadrio, 2006

José L. Blanco, Tomas Hrbek & Ignacio Doadrio, 2006, A new species of the genus Aphanius (Nardo, 1832) (Actinopterygii, Cyprinodontidae) from Algeria., Zootaxa 1158, pp. 39-53 : 43-49

Aphanius saourensis sp. nov.

Figs. 1, 4-5; Table 2.

Holotype. MNCN 246655 Male, 31.5 mm SL (Fig. 1). La tombe de Moché, Wadi (=Oued) Saoura, Mazzer, Algeria (Fig. 2). Geographic coordinates 30º19'N, 02º16'W. Coll. Nassim Louaileche, Dep. Herman Meeus; 19 October 2003.

Paratypes. MNCN 246649-246654 (6) ; MNCN 246656-246657 (2) ; MRAC A4-24- 8-1-3 (3) (measurements not taken). Same data as holotype.

Non-types. A series of live individuals, collected along with the types, have been brought back to the laboratory (and subsequently divided among facilities in Spain, Belgium, and the Netherlands) as stock for a species conservation program.

Diagnosis. Aphanius saourensis differs from its sister species, A. iberus and A. baeticus , by the following combination of characters: seven or eight (rarely nine) branched dorsal-fin rays (vs. eight or nine [rarely 10] branched dorsal rays in A. iberus ); longer preorbital length (PrOL/ED = 0.9-1.3 vs. 0.5-0.7) (Table 3); and relatively longer and more narrow caudal peduncle (CPL/BLD = 1.7-2.0 vs. 1.3-1.9 [rarely 2.0]) (Table 4). Body pigmentation of live males a profusely mottled blue and silver, not forming vertical bars (Fig. 4) vs. alternating silver to silver-blue and blue-grey bars and small irregular silver spots in A. iberus (Fig. 6) and A. baeticus (Fig. 7). Females without conspicuous black spots (except a spot at the junction of the caudal peduncle and central caudal fin rays) (Fig. 5) vs. one row of large and two to three rows of small black spots in the posterior half of the body in A. iberus and A. baeticus , respectively. Twenty-six molecular autapomorphies in the cytochrome b gene (Table 6) also differentiate A. saourensis sp. nov. from A. iberus and A. baeticus . Divergence in the cytochrome b gene is 4.9-5.8% compared to Aphanius iberus and 6.3-6.5% compared to Aphanius baeticus . Summaries of differences among the three species appear in tables 5 and 6.

Description. Morphometric data appear in Table 2. D. I -II, 7-8 (9) (-χ =7.6), A. I,9- 10 (-χ =9.6), P. I (12) 13-15 (-χ=13.7), V. I 4-5 (-χ=4.9), C. 13-15 (16) (-χ=14.6), LLS. 25- 26 (-χ=25.4). Body moderately elongated, maximum height 3.7 times in standard length in females and 4.1 times in males. Caudal peduncle narrow. Height of caudal peduncle 1.6 times the anal caudal peduncle length in females and 1.8 times in males. Height of caudal peduncle is 2.0 times in females and 1.9 times in males the dorsal caudal peduncle length. Head elongated, its length 3.6 times in standard length in females and 3.4 in males. Snout long, the preorbital length 3.0 times in head length in females and 4.2 times in males. Eye located in a forward position, its diameter 1.3 times in preorbital length in females and 1.0 time in males. Dorsal fin inserted before origin of anal fin, on the same axis. Preanal length 1.2 times longer than predorsal length in females and 1.1 times in males. Pectoral fin shorter than head length, its length 2.1 times in head length in females and 2.1 times in males. Ventral fin small, and in one individual (MNCN 246649) is absent. Tricuspid teeth in a single row.

Pigmentation Pattern. Live Males (Fig. 4): Mottled light blue and silver pattern without bars, with a tendency in some individuals to form bars in the area of the caudal peduncle. Dorsal, anal, and caudal fins with black spots forming vertical bars. Five bars on caudal fin, four on dorsal fin, and three to four on anal fin. Black line under lower lip. Iris silvery, pupil black. Paired fins hyaline, unpaired fins hyaline to opaque bluish-white.

Live Females (Fig. 5): Light brown body with irregular darker brown mottling tending to darken along the posterior third of lateral line, lighter on ventral region. Most individuals with a well defined dark spot at junction of caudal peduncle and central rays of the caudal fin. All fins colorless. Horizontal line under lower lip similar to males, but less conspicuous. Iris silvery, pupil black.

Sexual Dimorphism. There is clear sexual dimorphism in pigmentation pattern (Figs. 4 and 5). Females also appear to have a greater body size than males, although our small sample size precludes unequivocal confirmation of this.

Distribution. Only individuals of the Algerian population of Mazzer (30° 19'N, 2° 16'W; Fig. 2) inside the Oued Saoura basin could be collected and analyzed in this study. Villwock and Scholl (1982) analyzed specimens from Igli, Oued Zousfana basin, a tributary basin to the Saoura. Specimens from El Ouata ( MRAC 83-002-P-0082-0111) and Kerzaz ( MRAC A3-045-P-0906) are deposited in Royal African Museum in Tervuren , both of which are within the greater Oued Saoura basin (R. Wildekamp, com. pers.) and in geographic proximity to Mazzer; Kerzaz is the most distant locality, approximately 120 km away. Despite several attempts to collect at these localities, no Aphanius were found, and it can be assumed that the genus has been extirpated from these areas. However, morphological characters suggest these specimens are Aphanius saourensis . The distribution of Aphanius saourensis is therefore restricted to the Oued Saoura basin, and is presumed to have originally occurred throughout the entire region (Fig. 3). It is unlikely that other populations from Algeria ascribed to Aphanius iberus , such as those from Sebkra Oran, El Kreider, Oued Touil and Chott er Chergui (Pellegrin 1921; see also Fig. 3) belong to the new species or to A. iberus . Material from these areas has either not been deposited in a museum or has been lost. Recent efforts to recollect in these areas were unsuccessful.

Etymology. The species name “ saourensis ” comes from the geographical toponym “Saoura”, the name of the valley from which the type series was collected, and the only known locality with an extant population.

Proposed Common Names. Sahara Aphanius (GB/English); Afanius sahariano (E/ Spanish); Aphanius saharien (F/French); Saharischer Aphanius (D/German).

Conservation. This species should be considered critically endangered following IUCN criteria. The species is only known from one remnant population in the Sahara desert, having disappeared from numerous other localities of this same spring system (Kessel & Zee, 1984). The presence of introduced North American Gambusia sp. poses a serious threat, with current densities of Gambusia to Aphanius being more than 100 to one. Excessive ground water withdrawal for agricultural purposes, the drying of wetlands, and water pollution are, along with the introduced Gambusia , the major threats to the survival of this species. Its survival is unlikely in the wild, but a small captive breeding program is underway.

Comparative Data and Discussion

As discussed above, specimens of Aphanius from Mazzer, Algeria (Figs. 4-5) show many diagnostic genetic and morphological differences when compared to Spanish specimens of A. iberus (Fig. 6) and A. baeticus (Fig. 7), and are thus considered to represent a new species. Tables 5 and 6 provide summaries of differences between the three species.

Bayesian analysis of phylogenetic data supports the hypothesis that A. saourensis forms a well supported clade together with A. iberus and A. baeticus (see Fig. 8; Table 6). However, relationships among these three species are not well resolved. Assuming a molecular clock of 1% pair-wise sequence divergence per million year in cytochrome b (Dowling et al., 2002; Doadrio & Carmona, 2004), separation among the three species would coincide with the upper Miocene period and the Messinnian crisis. The actual distribution of A. iberus , A. baeticus , and A. saourensis occurs along the old coastline existing in the Miocene before to separation of the Betic-Rif Massif at the Miocene-Pliocene boundary 5.3 million years ago (Doadrio, 1994, Krijgsman et al., 1999a, Krijgsman et al., 1999b).