Leucos basak Heckel, 1843

Bianco, Pier Giorgio & Ketmaier, Valerio, 2014, A revision of the Rutilus complex from Mediterranean Europe with description of a new genus, Sarmarutilus, and a new species, Rutilus stoumboudae (Teleostei: Cyprinidae), Zootaxa 3841 (3), pp. 379-402 : 384-387

Leucos basak Heckel, 1843

( Figs. 2 B, 3B)

Leucos basak Heckel, 1843: 1006 (Type locality: Vergoraz and Lake Drusino, near Imotschi, Croatia).

Rutilus aula karamani Vladikov & Petit, 1930: 391 (type locality, Lake Ohrid, Albania). The authorship of this species is reported as Fowler, 1977 in Kottelat (1997) because Kottelat assumed that the original description was infrasubspecific ( Rutilus aula natio karamani ), which should not be made available (ICZN, 1999; art. 45.5). It should be noted, however, that Vladikov & Petit (1930) in the text of their original description used the name Rutilus aula karamani , without the use of “natio”, making clear their intention to describe a subspecific taxon (ICZN, 1999: art. 45.6.4.1).

Leucos aula var. ohridana Karaman, 1924: 56 (type locality, Lake Ohrid, FYROM)

Leucos aula var. prespensis Karaman, 1924: 57 (type locality, Lake Prespa, FYROM) Rutilus prespensis vukovici Marić, 1989: 65 (type locality, Lake Skadar, Montenegro) Examined materials. IZA 83120, 33, Croatia, R. Krupa (R. Neretva basin), P.G. Bianco, 28 May 1983.—IZA 0 48, 5, Croatia, L. Bačinska (R. Neretva basin), M. Mrakovic, 10 Aprile 1997.—IZA 0 0 164, 5, FYROM, L. Ohrid, R. Gruptché, 10 April 1970.—IZA 0 429, 30 (out of 122), FYROM; L. Ohrid, P.G. Bianco, 28–29 August 1987.—IZA 0 430, 10, FYROM, L. Ohrid, R. Gruptché, 13 March 1969.- IZA 85481, 30 (out of 232), Montenegro, L. Skadar, P.G. Bianco and B. Knezevic, 24–25 July 1984.—IZA 0 441, 4, Montenegro, L. Skadar, P.G. Bianco and D. Marić, 9 November 1999.—IZA 0 0 55, 5, FYROM: L. Prespa, P. Banarescu, 29 November 1975.—IZA 0 435, 10, FYROM, L. Prespa, R. Gruptché, 15 May 1968.—IZA 0 422, 12, Greece, lakes Prespa and Micraprespa, P.G. Bianco, 22 August 1998. – MNHN 1977.281, 3, Albania (syntypes of Rutilus karamanni Vladikov & Petit, 1930 ).

Diagnosis. A species of Leucos characterized by moderate size, usually 120–140 mm SL; absence of a midlateral band; body uniformly silvery in life; peritoneal membrane black.; usually 36–38 pored scales on LL, as opposed to 38–43 in the other Leucos species. It may be distinguished from Leucos aula for the absence of lateral band and the color of the peritoneal membrane, black in L. basak , and silvery in L. aula . It differs from L. panosi and L. ylikiensis mainly by the number of GR, which are usually 9–10 in L. basak and respectively, 18–20 in L. ylikiensis and 13–14 in L. panosi . The most closely related species, according to molecular analyses ( Fig. 1 B) is L. albus . The two species can be identified on the basis of the number of LL scales, usually 41–42 in L. albus and 36–38 in L. basak , the number of D branched rays, 9 in L. basak and 8 in L. albus , and apparently for the color of the peritoneal membrane, nearly silvery in L. albus , and blackish in L. basak .

Description. A small-medium sized species. In Croatia may reach 220 mm TL and 180 g of weight, but usually less than 150 mm TL ( Mačrovcić et al., 2006). Body uniformly silvery without longitudinal band; color of the eye in living animals is yellowish; fins yellowish or pale grayish in preserved specimens; snout pointed, preorbital distance near equal to the horizontal diameter of the eye; lips smooth; mouth opening oblique, the corner of maxillae at the same level of the vertical crossing the anterior border of the orbit; mouth terminal or slightly inferior; profile of dorsum convex sometimes humped in large specimens; paired and un-paired fins yellowish with few scattered melanophores, free margin of D and A concave; P1 longer in males, were may reach the origin of P2; caudal fin forked; peritoneal membrane blackened by several melanophores addensed and fused; head length about 3.6–3.8 times in the SL; body deep about 3.5–3.7 times in the SL; origin of the D at same level of the insertion of the P2; LL complete, and extending from the margin of opercular membrane, to the end of caudal peduncle, with 35–41 pored scales, usually 36–38; 7.5 above and 3.5 below the LL; constantly 3 un-branched rays followed by 9 branched rays in the D; constantly 3 un-branched and usually 8 branched rays in the anal fin; P1 with 1 unbranched and 14–15 branched rays; P2 with 1 un-branched ray and constantly 8 branched rays; usually 9–10 total GR; in adult males pearl organ absent. For additional description and shape, see Fig. 2 B and Tables 1, 2, 3.

Distribution. The species distribution includes lakes and mostly still water of rivers of the Adriatic drainages, from Croatia, till to Albany, and Montenegro. In Lake Skadar the species is sympatric with Leucos albus . In Croatia its distribution is limited to basins of south-eastern part: lakes Crven, Modro, Bačinska and rivers Matica and Neretva (Mracovčić et al., 2006).

Remarks on synonyms. According to mtDNA ( Ketmaier et al., 2008) and to the morphological analyses presented here on Leucos basak (Table 3) from the Dalmatian, Albanian, and Aegean ichthyogeographic districts (sensu Bianco 1990), the populations from lakes Ohrid, Prespa and Skadar and River Krupa (River Neretva drainage) cannot be unequivocally distinguished from one another and should be regarded as a single species. This would be partially at odds with the results of Milošević et al. (2011). These authors, based on mitochondrial (cyt- b) and nuclear (five polymorphic microsatellites) markers coupled with morphology proposed the existence of three species in the area ( Rutilus ohridanus , R. prespensis and R. albus ). It should be noted, however, that divergence at the mtDNA level was shallow (up to a maximum of five substitutions) and that the lack of gene flow at the nuclear loci could reflect the geographical isolation of these lakes rather than a specific status of the taxa. The authors themselves claimed that “ R. prespensis should be further evaluated to determine if the taxon is synonymous with other Rutilus from the Adriatic basin”.

Rutilus ohridanus is a problematic species as the diagnosis of meristic characters given in Karaman’s (1924) original description (D with 10–11 branched rays, A with 11 branched rays and 44 LL scales) overlaps with that given for R. pygus virgo for Lake Dojran (FYROM, Greece) in the very same paper. The overlapping in biometric characters with R. pygus virgo is very likely due to a printing error; also the maximum size reported Karaman (1924), (about 150 mm TL) would classify the species as a small sized Rutilus ( Ivanović, 1973; Soric, 1983; Marić, 1988), (see Tab 2). In our extensive survey of samples of R. basak (see above) we found neither 10/11 branched rays in D nor 10 in A. R. ohridanus should be then placed as synonym for R. basak . R. prespensis , R. p. vukovici and R. karamanni , cannot be separated from R. basak neither molecularly nor morphologically and are here regarded as junior synonyms for R. basak . Thus all the populations of the synonymized nominal taxa represent a single species; this would also reflect the hydrography of the Albanian district as these lakes are connected to one another: the lakes Prespa and Ohrid through a subterranean karstic channel, lakes Ohrid and Skadar through the Bojana-Drina river system. Lake Ohrid is considered to be the oldest continuously existing lake in Europe with a likely age of three to five million years. An extraordinarily high degree of endemism, including more than 210 described endemic species, renders the lake a unique aquatic ecosystem of worldwide importance ( Albrecht & Wilke, 2008), and the center of origins of native fish and biodiversity in the Albanian district. Lake Skadar, on the contrary, is relatively young and originated through flood of a karstic field occupying a crypto-depression of recent origin ( Lasca et al., 1981); it is thus reasonable to hypothesize that its fish fauna originated through multiple colonization events from surrounding water bodies.

Lectotype designation. Due to the high diversity of the genus Rutilus complex in the Balkan Peninsula (see Introduction and Ketmaier et al., 2008), a lectotype is here selected among the four syntypes housed in NMW 50723, and 50725. The specimen, 117 mm SL (151 mm TL), bearing the catalogue number NMW 50723-1 is designed as the lectotype. A picture of that specimen was published in Bianco & Taraborelli (1985: fig. 6, p.149). According to ICZN (1999), other things being equal, preference for selection of a lectotype should be given to a syntype that has been illustrated in a publication (art 74. recommendation 74A). The lectotype is in good condition ( Fig. 3 B). It has 40 pored scales on LL; 9 above and 4 below LL; 9 branched dorsal rays and 8 branched anal rays; pharyngeal teeth formula, 5-5. Head length about 3.8 times in SL; head depth 4.8 times in SL; body depth about 4.0 times in SL, least body depth about 2.3 times in body depth; snout length about 3.4 times in head length. Dorsal and anal fins slightly concave; caudal fin forked; origin of D at same level as origin of P2; mouth terminal and slightly oblique; dorsum quite convex.

Remarks on ecology, biology and conservation. It is a still-water adapted species, invasive in lakes Skadar, Ohrid and lakes of Adriatic drainages of Croatia, and low course of rivers. Spawning takes place between April and May ( Mačrovcić et al., 2006). Its conservation status is of “Low Concern” according to IUCN (2013) red list.

Figures

FIGURE 2. Native species of the Rutilus complex in southern Mediterranean Europe: A) Leucos aula, 115 mm SL, R. Bacchiglione, northern Italy, April 1996 (IZA 0425); B) Leucos basak, 95 mm SL, Lake Ohrid, FYROM, August 1987, (IZA 0429); C) Leucos ylikiensis, 120 mm SL, Lake Yliki, April 1987 (IZA 8733); D) Leucos panosi, 130 mm SL, canal to Lake Trichonis, May 1987 (IZA 8766); E) Leucos albus, 98 mm SL, River Moraca, Montenegro, November 1999 (IZA 0421); F) Sarmarutilus rubilio, 100 mm SL, River Ofanto, southern Italy, February 2002 (IZA 02183); G) Rutilus pigus, 230 mm SL, Lake Major, northern Italy, (IZA 0474); H) Holotype of Rutilus stoumboudae new species, 148 mm SL, October 1998, Lake Volvi, Greece (IZA 02107).

FIGURE 1. A) Collecting localities (L. = lakes, R. = rivers) of Rutilus complex species. 1, R. Thames; 2, R. Danube (Slovakia); 3, R. Danube (Romania); 4, L. Como; 5, L. Maggiore; 6, R. Arno and R. Serchio; 7, R. Albegna and R. Cecina; 8, R. Ombrone and R. Fiora; 9, R. Tiber and R. Mignone; 10, L. Trasimeno; 11, R. Liri and R. Garigliano; 12, R. Volturno and R. Sele; 13, R. Pescara and R. Tavo; 14, R. Trigno; 15, R. Tronto; 16, R. Livenza; 17, L. Pernica; 18, R. Sava; 19, L. Drusino; 20, R. Krupa (R. Neretva basin); 21, L. Besanka (R. Neretva basin); 22, R. Moraca and R. Zeta; 23, L. Skadar; 24, L. Dojran; 25, L. Horid; 26, L. Prespa and L. Micraprespa; 27, L. Vegoritis; 28, L. Volvi; 29, L. Joannina; 30, L. Yliki and L. Paralimni; 31, L. Ambrakia; 32, L. Trichonis. Bold numbers are the different peri-Mediterranean ichthyogeographic districts described in Bianco (1990). B) A schematic temporal reconstruction of the diversification of the genus in southern Mediterranean Europe based on cyt- b is shown (modified from Ketmaier et al., 2008). For each taxon the corresponding number of the district of origin is shown; triangles indicate that multiple populations were analyzed. Numbers at nodes are divergence times in million years; all labeled nodes were robustly supported in the phylogenetic reconstructions (see Ketmaier et al., 2008 for further details).

FIGURE 3. A) Lectotype of Leucos aula, 74 mm SL (ANSP 6434), Padua Province, northern Italy; B) Lectotype of Leucos basak, 117 mm SL (NMW 50723 - 1), Vergoraz and Lake Drusino near Imotsky, Croatia; C) Lectotype of Sarmarutilus rubilio, 93 mm SL (ANSP 6509), Lake Nemi, Central Italy.