Rutilus pigus (La Cepède, 1804), La Cepede, 1804

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 : 398-399

Rutilus pigus (La Cepède, 1804)

( Fig. 2 G)

Cyprinus pigus La Cepède, 1803: 503 , 607 (type localities: lakes Major and Como, northern Italy).

Examined material. IZA 0 471, 12, Italy, L. Como, O. Mangione, April 2004.— IZA 0 472, 3, Italy, R. Livenza, M. Povz, 22 May 1996.— MSNM (uncataloged), 33, Italy, L. Maggiore, A. Mojetta, June 1988.— IZA 843,6, Italy, R. Po, G. Delmastro, 13 March 1983.- IZA 842, 6, Italy, L. Major, April 1983, G. Giussani.

Diagnosis. Rutilus pigus , was only recently separated from R.virgo ( Kottelat & Frehyof, 2007; Ketmaier et a l., 2008). R. pigus , is endemic of Padany-Venetian district, and differs from R. virgo from central Europe, in squamation as it has 46–51 scales on LL, and 8.5 above and 3.5 below the LL, as against 40–46 scales on LL and 7.5 above and 3.5 below the LL in R. virgo . The two species show also a different position of nuptial tubercles on head ( Kottelat & Freyhof, 2007) and also phylogenetically are very distant (Ketamaier et al., 2008). Compared with R. rutilus , has more scales on LL scales, 46–51 in R pigus , and 39–44 in R. rutilus ; and less number of total GR, 9–12 in R. pigus and 12–16 in R. rutilus . Compared to R. stoumboudae n.sp., R. pigus has less total GR (12–15 vs. 15–18) and more branched rays both in the dorsal and anal fins (9–11 vs. 8–9).

Description. A species of Rutilus characterized by large size and the absence of mid lateral band. In reproductive males, well developed and large prominent nuptial tubercles on head, checks, and at center of the scales of the body. Absence, in reproductive males, of fan-shaped granular tubercles, on the free border of each scales of the body. Body laterally compressed, moderately elongate, dorsal profile convex; sometimes a small hump in largest specimens; snout pointed; eye diameter equal to the pre-orbital length; posterior mouth corner placed beyond the vertical crossing the anterior margin of orbital cavity; mouth opening oblique and terminal to slightly sub-terminal; lips smooth; eye small, its horizontal diameter less than or equal to the pre-orbital length; head length about 4.3–4.6 times in the SL; body quite deep, its depth about 3.2–3.4 times in the SL; origin of the D placed at same level of the insertion of the P2; free margin of dorsal and anal fins, from straight to slightly concave; caudal fin, when enlarged, moderately forked; LL complete, with 46–51 pored scales extending from the upper margin of opercular membrane, to the end of caudal peduncle; modally 3 un-branched and 10 branched rays in the dorsal and 11 in the anal fins; P1 with 1 un-branched and 15–17 branched rays; P2 with 1 un-branched ray and constantly 8 branched rays; about 8–12 total GR; color of the eye white; the color of all fins is from yellowish to dark grays; peritoneal membrane blackened by dense melanophores. For additional description and shape, see Fig. 2 G, and Tables 4, 5.

Distribution. Padano-Venetian district, from River Po to River Isonzo (upper Adriatic Sea drainages). Its survival is strongly affected by the introduction of two alien species: the European roach, Rutilus rutilus and the European nase, Chondrostoma nasus (Linnaeus, 1758) .

Remarks on ecology, biology and conservation. A mostly lacustrine adapted species, which may reach 500 mm TL and 2 kg of weight, and at least 9 years of age. Sexual maturity is late and is reached at age 3+ or 4+ in males and 5+ in females at about 280–330 mm SL. Reproduction takes place between April and May, longevity is up to 9 years ( Bianco & Taraborelli, 1985; Puzzi et al., 2007). Although the species was placed in the “Low Concern” category by (IUCN, 2013), according to the recent assessment made by the Italian National IUCN red list commission, R. pigus was placed in the “Critical Endangered” category ( Bianco et al., 2013). This species is progressively disappearing throughout its native range, mainly as a result of competition with the invasive introduced R. rutilus and Chondrostoma nasus ( Puzzi et al., 2007; Volta & Jepsen, 2008).

Rutilus stoumboudae Bianco & Ketmaier , new species ( Fig. 2 H)

Type materials. Holotype ( Fig. 2 H) IZA 02107A, 128 mm SL, Greece, Lake Volvi, P.G. Bianco, 21 October 1998 (specimen also used for molecular analysis by Ketmaier et al., 2008).

Paratypes: IZA 02107B, 11, 64– 156 mm SL, Greece, Lake Volvi; P.G. Bianco, 10 October 1998.

Diagnosis. Rutilus stoumboudae differs from R. rutilus , its closest relative genetically, both in the number of total GR (16–17 vs. 13–14) and number of branched rays of the D and A (modally 9 and 9 in R. stoumboudae and 10 and 10 in R. rutilus ). It differs from R. pigus in apparently lacking nuptial tubercles, in the numbers of LL scales (39–43 vs. 46–51) and of branched rays in the anal fin (8–9 vs. 9–11).

Description. Apparently a small to medium sized species. Maximum SL observed, 156 mm and 197 mm of TL in our materials. Body moderately compressed, its depth about 3.1–3.3 times in SL. Head length about 3.8–4.0 times in SL. Mouth, small, terminal and slight up-turned. Pre-orbital distance less than eye diameter. Eye diameter about 2.7–3.3 times in head length. Origin of D slight behind the origin of P2. Free margins of D and A concave; dorsal profile convex, slightly humped in the holotype; pre-dorsal distance slightly longer than pre-ventral distance. Pectoral-pelvic distance nearly equal to pelvic-anal distance. Caudal peduncle depth about 1.1–1.3 times in caudal peduncle length. Free margin of pectoral and pelvic fins rounded, caudal fin, when extended, moderately forked. D with 3 non-branched and 9 (in one case 8) branched rays. A with 3 non-branched and 9 branched rays. Fourteen circum-peduncular scales; 38–41 pored scales on the LL. 7.5 or 8.5 rows of scales above and 3.5 or 4.0 below the LL; 8–10 total GR; pharyngeal teeth on both sides, 6-5; Peritoneal membrane darkened by dense melanophores; apparently absence of tubercles. Ground color silvery; back plain dark brown. Top of head plain dark brown; sides light; ventral surface of head, belly and caudal peduncle yellowish. All fins yellow-brownish. General shape of holotype in Fig. 2 H. Morphometric and meristic data of holotype and 11 paratypes in Tables 4, 5.

Remarks. According to Larmuseau et al. (2009), the species from Lake Volvi examined by Ketmaier et al. (2008), should be identified as Rutilus heckeli . But these authors specifically stated in their study that the identification of the alleged Rutilus heckeli material they used was uncertain: the authors did not deposite the corresponding sequences in GenBank and we are thus unable to include their data in our phylogenetic analyses. According to Larmuseau et al. (2009), Rutilus heckeli seems the sister species of R. rutilus . Extensive diagnosis of this species is found in Berg (1949), and Banarescu (1964): it may reach the size of about 500 mm TL (size unknown in Lake Volvi, since Rutilus stoumboudae belongs to a group of species of smaller size). Adult males of Rutilus heckeli show well developed nuptial tubercles all along the dorsal area of the body (apparently not found in R. stoumboudae ); pharyngeal teeth formula is modally 6- 6 in R. heckeli , while in our new specie is modally 6-5; the number branched rays of dorsal and anal fins are modally 10 in R. heckeli , and 9 in R. stoumboudae . Based on these differences we cannot identify samples of the new species as Rutilus heckeli . Another geographically close species, described for the River Maritza in Bulgaria (Evros in Greece), Rutilus maritza, Drenski, 1926 , is considered since a long time as a junior synonym of R. rutilus ( Kottelat, 1997) . In addition, the Bulgarian freshwater fish fauna is of Danubian origin, with the exception of a single endemic species, Alburnus mandrensis (Drensky, 1943) .

Color pattern. In preserved specimens, dorsum brownish, sides yellowish without a longitudinal band. Scales of flanks show a reticulate pigmentation. Peritoneal membrane with more or less concentrated or scattered melanophores. Pectoral, dorsal, and caudal fins black; pelvic and anal fins yellowish.

Distribution: There are several doubts about the native origin of this species in Lake Volvi. Kottelat & Frehyof (2007) reported a Rutilus sp. from River Sperchios (south-eastern Greece). According to the count methodology proposed in Bianco & Kottelat (2005) the species shows 9 branched rays in the anal and in the dorsal fins. Among the Rutilus species revised in this contribution, only the new species possess 9 branched rays in the dorsal and anal fins. The general shape of the specimens from the River Sperchios described by Kottelat (2007: p 249) is very similar to that of the holotype of R. stoumboudae .

Translocations of fishes by fishermen from southern Greece basins to the shore market of Lake Volvi for selling seems quite frequent. Leucos ylikiensis and Scardinius acarnanicus , endemic to Lake Yliki, have been transplanted in Lake Volvi following this practice.

Etymology. The species is named after the Greek ichthyologist, colleague and friend, Maria Stoumboudi, in honor of her research activity on the ecology and conservation of freshwater fishes of Greece.

Remarks on ecology biology and conservation: a still water adapted species. No data available on its biology. According to the IUCN (2012) category, it satisfies point B and potentially should be placed in the “Endangered category” as the area of occupancy is less than 500 km 2 and the species keeps declining as a result of habitat reduction.

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).