Alburnus, Rafinesque, 1820

Alburnus View in CoL

The genus Alburnus (43 species) is a large group of smallto medium-sized fishes widely distributed in Europe, West, and Central Asia. In West Asia, Alburnus , with 24 species, is the second-largest genus of Leuciscids after Pseudophoxinus . Previous studies have overestimated the species diversity of Alburnus , as several shemayas of the A. chalcoides group have been recognised as separate species based on morphometric and meristic differences. All these populations are closely related, and recent research only partly confirms the differences proposed before and/or found the character states to be more overlapping than proposed. Therefore, Asian shemayas from the Aegean, Marmara, and Black Sea basins are placed in A. derjugini . The Central Asian A. taeniatus had been reported from the Hari in Iran. However, as the identification of this fish could not be confirmed, it is excluded from the coverage of this book.

Molecular characters group the species of Alburnus into three major species complexes, which may be recognised as separate genera in the future. True bleaks form one group, spotted bleaks belong to the second group, and Shah Kuli’s belong to a third group. Sunbleaks of the genus Leucaspius and saramugos of the genus Anaecypris are closely related to, or even nested within, Alburnus . Alburnus are typically pelagic open-water dwelling fish that feed on plankton, drifting invertebrates, and small terrestrial arthropods that have fallen on the water surface. They are often common or very common and play important roles in the ecosystems they inhabit. In general, Alburnus are slender, silvery, herring-like fish with a superior or terminal mouth, a partly or completely open keel between the anus and the pelvic base, and a long anal fin with more than 9½ branched rays. However, several species do not fit this description, as they have fewer anal rays, no ventral keel or the keel completely covered by scales, and a clearly terminal or even subterminal mouth. Based on anatomical studies, these species were previously classified within the genus Petroleuciscus .

However, subsequent molecular studies led to their reclassification within the genus Alburnus .

Keys to species of Alburnus in West Asia

Caspian and Lake Urmia basins

1a - Usually 7½ branched dorsal rays....……………… A. filippii

1b - Usually 8½ branched dorsal rays....……………… 2

2a - 7–10½ branched anal rays; ventral keel between pos- terior pelvic base and anus absent or very shallow....……………… A. ulanus

2b - 9–16½ branched anal rays; ventral keel between posterior pelvic base and anus present and well devel- oped. ...………………3

3a - 38–43+2–3 lateral line scales...……………… A. hohenackeri

3b - 43–65+2–5 lateral line scales ...………………4

4a - 13–15½ branched anal rays; 18–23 gill rakers; flank plain silvery without midlateral stripe in life or with very indistinct stripe; ventral keel not exposed in front of anus....……………… A. chalcoides

4b - 9–12½ branched anal rays; 10–15 gill rakers; a prom- inent dark-brown midlateral stripe in life and preserved individuals; ventral keel exposed for 1–4 scales in front of anus....……………… A. atropatenae

Persian Gulf basin, Qweiq, Lake Van, and Iranian endorheic basins, excluding Lake Urmia

1a - Anal origin below dorsal base....……………… 2

1b - Anal origin below last branched dorsal ray or behind dorsal base....……………… 3

2a - Adults with a mottled bluish-grey colour pattern on flank, just few dark-grey scales on flank in some indi- viduals....……………… A. caeruleus

2b - Adults silvery, never with dark-grey scales or blotches or with mottled bluish-grey colour pattern....……………… A. hohenackeri

3a - Ventral keel between posterior pelvic base and anus absent or very shallow, completely covered by scales....……………… 4

3b - Ventral keel between posterior pelvic base and anus present, scaleless along at least 5 scales....……………… 5

4a - Usually 13–17 gill rakers....……………… A. doriae

4b - 8–12 gill rakers....……………… A. kurui

5a - Ventral keel completely scaleless or one scale on keel behind pelvic base; flank scales with prominentdark-grey margins; mid-lateral stripe absent or very faint....……………… A. tarichi

5b - Ventral keel covered by one or more scales; flank scales without grey margins or irregular set grey pig- mentation; mid-lateral stripe distinct, often bold....……………… 6 6a - Lateral line with 51–65(–72)+3 scales; head depth at nape 16–18 % SL; postorbital distance 12–15 % SL....……………… A. timarensis

6b - Lateral line usually with 63–83+3 scales; head depth at nape 14–16 % SL; postorbital distance 10–12 % SL....……………… A. sellal

Central Anatolia, Aegean, Marmara, and Black Sea basins

1a - 72–90 total lateral line scales. ...……………… A. akili

1b - 38–72 total lateral line scales. ...………………2

2b - 52–69+3–5 lateral line scales; anal origin below last branched dorsal ray or behind dorsal base. ...……………… A. derjugini

2a - 38–56+2–3 lateral line scale; anal origin below dorsal base. ...………………3

3a - 16–19½ (rarely 15½) branched anal rays....……………… A. alburnus

3b - 10–15½ branched anal rays. ...………………4

4a - 18–21 gill rakers....……………… A. demiri

4b - 11–19 gill rakers. ...………………5

5a - 40–47 total lateral line scales; 6–8 scale rows between lateral line and dorsal origin. ...……………… A. carianorum

5b - 45–59 total lateral line scales; 8–10 scale rows between lateral line and dorsal origin. ...………………6

6a - In life, flank with a prominent golden upper and black lower stripe; body depth at dorsal origin 19–24 % SL; ventral keel exposed for 7–10 scales in front of anus....……………… A. goekhani

6b - In life, flank without stripes or golden upper and black lower stripe faint; body depth at dorsal origin 24–30 % SL; ventral keel exposed for 0–5 scales in front of anus. ...……………… A. escherichii

Mediterranean basin

1a - 58–89, usually 66–86 total lateral line scales....……………… A. sellal

1b - 45–66 total lateral line scales....……………… 2

2a - 60–66 total lateral line scales....……………… A. adanensis

2b - 45–62 total lateral line scales....……………… 3

3a - Pelvic axillary scales absent; scales on back, flank, and belly reduced, often not overlapping, absent on belly in front of pelvic base....……………… A. baliki

3b - Pelvic axillary scales present; scales on back, flank, and belly well developed, overlapping. ...………………4

4a - 12–15½ branched anal rays....……………… 5

4b - 9–11½ branched anal rays....……………… 6 5a - Last unbranched dorsal ray stiff; anal origin behind vertical of last dorsal ray....……………… A. orontis

5b - Last unbranched dorsal ray soft and flexible; anal origin below dorsal base....……………… A. escherichii

6a - Flank plain silvery or with a distinct dark-brown mid-lateral stripe; 49–59 total lateral line scales....……………… A. kotschyi

6b - Flank with many irregularly set and shaped grey, dark- brown or black blotches; 45–52 total lateral line scales....……………… 7

7a - Anal origin below 5th or 6th branched dorsal ray; 3 scale rows between lateral line and anal origin; fuzzy and usually blurred pattern of bold black or brown scales....……………… A. qalilus

7b - Anal origin below or behind vertical through last dorsal ray; 4–5 scale rows between lateral line and anal origin; bold black, grey or brown scales on silvery or brown background. ...……………… A. magnificus