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A chub of previously ambiguous identity from the Boljunscica and Pazincica rivers (south-eastern Istra Peninsula) was studied and compared with geographically close Squalius squalus, Squalius zrmanja, and Squalius janae recently described from the Dragonja River drainage in the Adriatic Sea basin in Slovenia. It was shown that the chub from the south-eastern Istra Peninsula differs from all know species of Squalius but one: Squalius janae. Three samples examined from Boljunscica and Pazincica rivers and Squalius janae from its type locality, Dragonja River, show the following characters typical for the latter species: a long head (the head length 27–32% SL); a pointed conical snout with a clearly projecting upper jaw; a long straight mouth cleft, the lower jaw length (39–45% HL) exceeding the caudal peduncle depth; a large eye; commonly 9? branched anal-fin rays; commonly 44 total vertebrae (24+20 or 25+19); bright silvery colouration, scales easily lost; iris, pectoral, pelvic and anal fin pigmentation with yellow shades. The data on the distribution of Squalius chubs in the northern Adriatic basin support the assumption that the range of Squalius janae is determined by the geology of the Trieste Flysch Basin and the Pazin Flysch Basin forming the base of the Istra Peninsula. The distribution pattern of this species does not support a simple model of fish dispersal and a complete connectivity within the whole Palaeo-Po historical drainage. Indeed, it indicates a disrupted surface palaeohydrography that was heavily fragmented by karstification in the whole Dinaric area.
freshwater fish distribution, Cyprinidae, Istrian chub, Squalius, morphology, Adriatic Sea basin, Istra Peninsula, Slovenia, Croatia
Istra [Istria, formerly Histria], is the largest peninsula in the Adriatic Sea. It is located in the northern Adriatic between the Gulf of Trieste and the Bay of Kvarner, and shared by three countries: Croatia, Slovenia and Italy. The largest portion, Hrvatska Istra [Croatian Istria] lies in Croatia. Larger rivers of the western cost of the Istra Peninsula are (from north to south) Osapska Reka [Osbo], Rižana [Risano], Badaševica [Kornalunga] (with a reservoir called Vanganel Lake), Dragonja with its largest tributary Pinjevec [Rokava], and Mirna [Quieto], which is the largest river in Istra. The Butoniga River, a tributary of the Mirna, was dammed in 1989 in its upper part and now flows into a reservoir called Butoniga Lake. In the south-east from the Mirna, Pazinčica [Foiba, Fojba] River flows for 16.5 km and in the Pazinska Jama [Pazin Cave] becomes a subterranean river which used to flow underground near Beram, Kringa and Dvigrad to the sea forming the Lim Valley; its former estuary is the Lim Bay [Limski Kanal]. Rivers Raša [Arsia] (flowing into the Raški Zaljev [Raski Inlet, Porto d’Arsia] and Boljunšćica [Boljunčica] (used to flow into the Plumin Luka Inlet or Plumin Bay) go southwards along the western slope of the Učka mountains [Monte Maggiore] and the Ćićarija [Ciceria] mountain range. At present, the Boljunšćica and Raša drainage systems in the region of Čepić Polje (ca. 45°12'N; 14°08'E) are interconnected by a number of irrigational canals and canalised streams. Till 1932 Čepić Polje had been a lake, which is now drained.
Chubs were known to occur in the Istra
Peninsula, and historically they were identified as Squalius cavedanus (Bonaparte, 1838)in Osapska
Reka and Rižana (
The purpose of the present article is to describe the chub from Pazinčica and Boljunšćica rivers (south-eastern Istra), compare it with Squalius janae and Squalius squalus, and decide on its identity.
Material and methodsMeasurements were taken point to point to the nearest 0.1 mm
following
Abbreviations used: CBD, Collection of G.A.C. Balma and G.B. Delmastro, Torino; NMW, Naturhistorisches Museum Wien; SMNH, Slovenian Museum of Natural History, Ljubljana; PZC, Collection of P. Zupančič, Dolsko (Slovenia); ZISP, Zoological Institute, Russian Academy of Sciences, St. Petersburg; CNHM, Croatian Natural History Museum, Zagreb.
Material from the south-eastern Istra PeninsulaSqualius janae. NMW 3077–080, 7, 160.1–186.8 mm SL; Croatia: Čepić Lake; Steindachner don., V.1900. – NMW 49229, 16, 120.1–168.4 mm SL; same locality and donator, 1900 v.2a. – NMW 49250, 1, 222.8 mm SL; Croatia: Čepić Lake; coll. Krauss, August 1877. – PZC 406, 29, 49.5–133.2 mm SL; Croatia: Boljunšćica River at Katun Boljunski, ca. 45°17'N; 14°08'E; coll. Zupančič, 4 September 2004. – PZC 457, 5, 74.5–160.6 mm SL; same locality and collector; 3 September 2007. – PZC 415, 16, 50.8–118.0 mm SL; Croatia: Pazinčica River, ca. 45°14'N; 13°55'E; 13 July 2000, coll. Mrakovčić; CNHM 5005, 5002, 6021 and 5164, 4, 96.6–113.0 mm SL; Croatia: Istra Peninsula [no exact locality, probably Pazinčica]; no date, leg. Leiner.
Comparative MaterialSqualius janae. SMNH 207, holotype 183.7 mm SL; Slovenia: Dragonja River about 2 km upstream from bridge on road from Župančiči, 45°28'N; 13°46'E; coll. Zupančič, 1 August 2008. –PZC 475, 6 paratypes, 85.9–174.9 mm SL; same data as holotype. – PZC 452, 6 paratypes, 74.9–132.5 mm SL; Slovenia: Dragonja River at bridge on road from Župančiči, 45°28'15"N; 13°45'11"E; coll. Zupančič, 24 November 2007. – PZC 453, 6 paratypes, 66.2–157.6 mm SL; same locality; coll. Zupančič, 17 May 2009. – PZC 454, 19 paratypes, 85.8–158.0 mm SL; Slovenia: Dragonja River d downstream from confluence with Pinjevec [Rokava], 45°28'30"N; 13°44'31"E; coll. Zupančič, 10 April 2009. – PZC 455, 7 paratypes, 68.4–212.7 mm SL; Slovenia: Dragonja River south from Koštabona, 45°28'20"N; 13°44'11"E; coll. Zupančič, 10 April 2009. – PZC 456, 8 paratypes, 111.2–190.0 mm SL; Slovenia: Dragonja drainage: Pinjevec River [Rokava] at Župančiči, 45°29'N; 13°46'E; coll. Zupančič, 1 February 2007. – PZC 476, 4 paratypes, 80.4–120.0 mm SL; same locality and collector; 24 November 2007. – ZISP 54690, 11 paratypes, 88.5–149.3 mm SL; same locality as PZC 455; coll. Zupančič and Naseka, 5 July 2008.
Squalius squalus (samples are presented below in geographical order, from north-west to south-east). NMW 48920, 1 [probable syntype] of Squalius tyberinus Bonaparte, 1841, 187 mm SL; Italy: Tyber; “[C.L. Bonaparte], 1844.VI.19”. – NMW 49189, 5, 65.7–193.8 mm SL; Treviso; “[Tausch], 1844.V”. – NMW 49259, 4, 150.6–195.5 mm SL; Slovenia: Rižana [Risano, 1848.I.10]. – PZC 287 (from CBD–F1996/44384–44391), 8, 80.5–155.4 mm SL; Italy: Po drainage: stream Orco, 100 m from confluence with Po River at Chivasso, 45°12'N; 07°53'E; coll. Balma and Delmastro, 18 September 1991. – PZC 288 (from CBD–F2057/45572–45576), 5, 75.5–140.5 mm SL; Italy: Po drainage: Torrente Malone, about 1 km upstream of the bridge of Lombardore, 45°14'N; 07°44'E; Balma and Delmastro, 12 May 1992. – PZC 458, 4, 140.0–185.0 mm SL; Slovenia: Soča drainage: Nadiža [Natisone] River at Podbela, 46°14'30"N; 13°27'30"E; coll. Zupančič, 2 May 2007. – PZC 459, 3, 139.3–185.0 mm SL; Slovenia: Soča drainage: Idrija [Idria] River at Velendol, 46°05'N; 13°34'E; P. Zupančič, 2 May 2007. – PZC 460, 5, 107.0–145.0 mm SL; Slovenia: Soča drainage: Idrija system, Koncnar River, 45°59'N; 13°22'E; coll. Zupančič, 8 December 2007. – PZC 461, 12, 120.0–220.0 mm SL; Slovenia: Soča drainage: Idrija system, Birša River at Dolnje Cerovo, 45°58'N; 13°33'E; P. Zupančič, 26 April 2007. – PZC 462, 4, 140.0–215.0 mm SL; Slovenia: Soča drainage: Vipava [Vipacco] system, Močilnik River at Slap; 45°50'N; 13°56'E; P. Zupančič, 26 April 2007. – PZC 463, 7, 135–205 mm SL; Slovenia: Soča drainage: Vipava system, River Močilnik at Vipava, 45°50'08"N; 13°57'E; coll. Zupančič and Naseka, 6 August 2009. – ZISP 54687, 13, 107.8–208.2 mm SL; Slovenia: Soča drainage: Vipava system, Branica River at Steske, 45°52'30"N; 13°46'E; coll. Zupančič and Naseka, 5 July 2008. – PZC 465, 2; Slovenia: Soča drainage: Vipava system, Vrtovinšček River at Fuzine, 45°53'40"N; 13°48'40"E; coll. Zupančič and Naseka, 5 July 2008. – PZC 466, 14, 98.5.0–190.0 mm SL; Slovenia: Soča drainage: Vipava system, Vogršček River at Vogrsko; 45°50'N; 13°56'E; coll. Zupančič, 1 December 2007. – PZC 467, 9, 97.0–155 mm SL; Slovenia: Osapska Reka River (flows into Miljski Zaliv east of Muggia) at Osp, 45°33'N; 13°52'E; coll. Zupančič, 1 February 2007. – ZISP 54689, 7, 96.7–165.5 mm SL; same locality as PZC 467, coll. Zupančič and Naseka, 10 July 2008. – ZISP 54689, 6, 88.0–190.6 mm SL; Slovenia: Rižana River (flows into Miljski Zaliv at Koper [Capadistria]) at Dekani, 45°32'30"N; 13°48'E; coll. Zupančič and Naseka, 5 July 2008. – PZC 468, 2, 175, 182 mm SL; Croatia: Malinska River (endorheic, south from Dragonja) at Koromači Buskini, 45°27'N; 13°50'E; coll. Zupančič, 28 March 2009. – PZC 469, 4, 129.5–172.7 mm SL; Croatia: Mirna River at Livade, 45°21'N; 13°50'E; coll. Zupančič, 4 August 2005. – PZC 470, 7, 112.5–176.5 mm SL; Slovenia: Reka [Bračana] River, tributary of Mirna, at Olika, 45°27'40"N; 13°53'40"E; coll. Zupančič, 12 November 2008.
Lists of
examined specimens of Squalius cephalus, Squalius cf. squalus, Squalius zrmanjae, Squalius svallize, Squalius illyricus, Squalius prespensis, and Squalius orientalis can be found in
A map showing the localities of samples from the Istra Peninsula is given in Fig. 1.
Map showing the main localities mentioned in the text: 1Osapska Reka 2 Rizana 3 Badasevica and Vanganel Lake 4 Dragonja with Pinjevec 5 Mirna with Reka and Butoniga 6 Pazincica 7 Rasa 8 Boljunscica 9 Cepic Polje (formerly Cepic Lake) 10 Rjecina 11 Dubracina and Tribalj Reservoir 12 Ricina. Localities where Squalius janaeis recorded are circled.
Description of specimens from Boljunšćica and Pazinčica rivers. Morphometric data of 30 specimens from the Boljunšćica and Pazinčica rivers are given in Table 1, and the general appearance can be seen from Figs 2–5.
The body is elongate, depth at the dorsal-fin origin is 21–24% SL. The head is long, its length, 27–31% SL, is greater than the body depth being 113–131% of the latter, and exceeds the caudal peduncle depth by a factor of 2.6–3.2. The upper head profile is almost straight, the snout is pointed, and the preorbital part of the head is almost triangular in lateral view. The mouth is subterminal (Figs 2, 3) or almost terminal though never clearly terminal even in smaller specimens (Fig. 4), and the upper jaw is clearly projecting beyond the lower jaw. The mouth cleft is straight, oblique, and the lower jaw-quadrate junction is commonly well visible forming a distinctive obtuse angle (Figs 2–5); the lower jaw-quadrate junction is on the vertical through the middle of the eye. The lower jaw length, 39–44% HL, exceeds the caudal peduncle depth by a factor of 1.0–1.3, commonly 1.1–1.2. The length of the lower jaw is always greater than both the operculum depth (being 106–116% of the former) and the interorbital width. The eye is large, its horizontal diameter being 20–25% in HL, and 54–71% in interorbital width. The eye diameter negatively correlates with the fish size as it can be seen from comparisons of larger and smaller specimens (Figs 2–3 and 4), for example, it is 26–28% in HL in specimens of 50–60 mm SL and 20% in HL in a specimen of 222 mm SL (NMW 49250) though we did not perform a statistic comparison.
The dorsal fin has 3 simple and 8½ branched rays in all specimens. Its outer margin is straight. The dorsal fin is located slightly behind the end of the pelvic-fin base. The dorso-hypural distance falls when measured anteriorly in the posterior half of the eye, rarely at the posterior eye margin. The dorsal fin is high, its depth being 16–19% in SL. The anal fin has 3 simple and 9½ branched rays; 8½ branched rays were found only in two specimens. The anal-fin outer margin is slightly to markedly convex.
The total number of gill rakers in the outer row on the first left gill arch is 8(5), 9(22) or 10(3). Pharyngeal teeth (in five specimens examined) are 2.5–5.2, hooked and serrated. The number of total lateral line scales is 43(1), 44(2), 45(12), 46(11), 47(9) or 48(3). Scales on flanks are easily lost in both live and preserved specimens. The total vertebrae including four Weberian vertebrae and the l last complex centrum are 44 in 10 specimens examined; the number of abdominal vertebrae (including intermediate ones; precaudal vertebrae auctorum) is 24(5) or 25(5); the number of predorsal vertebrae (anterior t to the first dorsal pterygiophore) is 15(9) or 16(1); intermediate vertebrae are five in all specimens; the number of caudal vertebrae is 19(5) or 20(5). The vertebral formulae are 25+19 (5) or 24+20 (5) (Fig. 5).
In live specimens, the overall colouration has a strong silvery tint, and the back is only slightly darker than the flanks and the belly. No conspicuous dark reticulated pattern has been seen in live specimens. The iris, anal and pectoral fin pigmentation has yellow shades, and is never bright (Fig. 2). Formalin fixed and ethanol stored specimens keep silvery-grey colouration with no brownish or bronze shades; yellow pigments are often lost in preserved specimens. Pigmentation on scales shows a reticulate pattern with comparatively fewer pigment dots along the outer scale margins. A concentration of pigment on scale pockets forming dark vertical spots is commonly visible in larger specimens (Fig. 2) though not pronounced in a small specimen (50 mm SL, Fig. 3).
The Pazinčica and Boljunšćica specimens and the historical sample
from Čepić Lake examined in this study are thus identified as Squalius janae based on the diagnostic characters
of the latter (
Comparative remarks. The Pazinčica and Boljunšćica specimens
and the Čepić Lake historical sample differ from Squalius squalus in general and from specimens from
Osapska, Rižana (Fig. 6), Malinska and Mirna
rivers in the northern Istra Peninsula in particular (see
Squalius zrmanjae (Zrmanja and Krka Rivers) is
another species geographically close to Squalius janae. A morphological comparison between
the two species and between Squalius janae and Squalius illiricus distributed in Cetina and Krka
can be found in
Squalius janae, live specimen. PZC 457, 160.6 mm SL, Croatia: Boljunscica.
Squalius janae NMW 49229, 147.5 mm SL, Croatia: former Cepic Lake.
Squalius janae PZC 406, 50.0 mm SL, Croatia: Boljunscica.
Radiograph of Squalius janae, PZC 406, 133.2 mm SL, Croatia: Boljunscica, showing 24+20 total vertebrae (arrow shows first caudal vertebra) and lower jaw length (arrow shows posterior end of lower jaw).
Dragonja (PZC 475, 452-54, ZISP 54690, holotype SMNH 207, n=42) | Boljunšćica (PZC 406, 457, n=20) | Pazinčica (PZC 415, n=10) | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Min | Max | Mean | SD | Min | Max | Mean | SD | Min | Max | Mean | SD | n | SD | |
SL, mm | 63.3 | 190.0 | 80.0 | 160.6 | 75.3 | 118.0 | ||||||||
Body depth at dorsal-fin origin (% SL) | 20.4 | 26.1 | 23.16 | 1.09 | 20.9 | 23.6 | 22.48 | 0.87 | 22.9 | 25.2 | 23.41 | 0.86 | ||
Depth of caudal peduncle (% SL) | 9.7 | 11.0 | 10.46 | 0.38 | 9.8 | 10.9 | 10.37 | 0.38 | 9.3 | 10.8 | 10.37 | 0.48 | ||
Depth of caudal peduncle (% length of caudal peduncle) | 47.9 | 58.8 | 54.31 | 3.32 | 47.47 | 58.30 | 53.09 | 3.21 | 49.1 | 57.4 | 54.43 | 2.64 | ||
Predorsal length (% SL) | 55.4 | 59.0 | 57.04 | 1.06 | 55.6 | 58.4 | 56.61 | 0.87 | 57.1 | 59.3 | 58.00 | 0.83 | ||
Postdorsal length (% SL) | 32.6 | 36.2 | 34.17 | 0.95 | 34.3 | 35.7 | 35.11 | 0.47 | 32.6 | 35.4 | 33.94 | 1.12 | ||
Preanal length (% SL) | 71.2 | 76.0 | 74.05 | 1.30 | 71.0 | 74.4 | 72.60 | 0.96 | 70.6 | 73.7 | 72.56 | 1.04 | ||
Pectoral – pelvic-fin origin length (% SL) | 24.3 | 29.0 | 26.76 | 1.20 | 24.4 | 26.8 | 25.70 | 0.75 | 25.5 | 26.6 | 26.20 | 0.37 | ||
Pelvic – anal-fin origin length (% SL) | 19.3 | 22.7 | 21.32 | 0.85 | 19.7 | 22.8 | 21.38 | 0.98 | 20.2 | 22.3 | 21.43 | 0.86 | ||
Length of caudal peduncle (% SL) | 18.0 | 21.1 | 19.31 | 0.89 | 18.1 | 21.0 | 19.58 | 0.83 | 18.5 | 19.4 | 19.05 | 0.32 | ||
Dorsal-fin base length (% SL) | 10.1 | 12.1 | 10.98 | 0.60 | 9.9 | 11.6 | 10.92 | 0.42 | 10.0 | 11.0 | 10.65 | 0.35 | ||
Dorsal fin depth (% SL) | 16.3 | 20.2 | 18.09 | 1.32 | 17.4 | 19.4 | 17.91 | 0.57 | 16.1 | 19.1 | 17.62 | 1.04 | ||
Anal-fin base length (% SL) | 9.7 | 11.0 | 10.48 | 0.66 | 10.0 | 11.4 | 10.79 | 0.46 | 9.9 | 11.1 | 10.46 | 0.51 | ||
Anal fin depth (% SL) | 12.5 | 16.1 | 14.28 | 0.98 | 13.3 | 15.8 | 14.63 | 0.64 | 13.4 | 15.0 | 13.99 | 0.61 | ||
Pectoral fin length (% SL) | 18.8 | 22.0 | 20.17 | 0.94 | 18.8 | 21.6 | 19.92 | 0.81 | 18.5 | 20.7 | 19.83 | 0.78 | ||
Pelvic fin length (% SL) | 15.2 | 17.6 | 16.21 | 0.74 | 15.4 | 17.1 | 16.36 | 0.57 | 14.3 | 16.5 | 15.69 | 0.79 | ||
Head length (% SL) | 28.6 | 31.6 | 29.44 | 0.80 | 27.1 | 29.6 | 28.15 | 0.64 | 28.1 | 30.2 | 29.09 | 0.77 | ||
Head length (% body depth) | 111.0 | 137.2 | 123.07 | 6.18 | 118.08 | 131.03 | 125.33 | 3.69 | 112.6 | 129.6 | 119.33 | 5.40 | ||
Head depth at nape (% SL) | 17.3 | 18.8 | 18.07 | 0.51 | 16.14 | 18.40 | 17.36 | 0.70 | 17.0 | 18.3 | 17.53 | 0.46 | ||
Head depth at nape (% HL) | 59.1 | 64.2 | 61.39 | 1.63 | 58.2 | 64.6 | 61.67 | 1.92 | 58.9 | 62.6 | 61.29 | 1.28 | ||
Head depth through eye (% HL) | 42.3 | 47.5 | 44.55 | 1.43 | 41.6 | 48.1 | 44.61 | 1.84 | 42.7 | 46.3 | 44.44 | 1.54 | ||
Maximum head width (% SL) | 14.9 | 18.9 | 15.98 | 1.07 | 14.13 | 15.34 | 14.68 | 0.36 | 14.9 | 15.8 | 15.34 | 0.38 | ||
Maximum head width (% HL) | 50.8 | 60.3 | 54.29 | 1.64 | 50.4 | 54.1 | 52.15 | 1.10 | 51.3 | 54.2 | 52.74 | 1.23 | ||
Snout length (% SL) | 8.4 | 9.7 | 8.97 | 0.42 | 7.81 | 9.00 | 8.32 | 0.39 | 8.0 | 9.1 | 8.54 | 0.40 | ||
Snout length (% HL) | 28.1 | 32.4 | 30.46 | 1.19 | 27.9 | 31.6 | 29.57 | 1.25 | 27.5 | 30.6 | 29.36 | 0.96 | ||
Eye horizontal diameter (% SL) | 5.6 | 7.8 | 6.56 | 0.50 | 5.60 | 6.85 | 6.23 | 0.42 | 6.2 | 7.2 | 6.76 | 0.44 | ||
Eye horizontal diameter (% HL) | 19.3 | 25.2 | 22.27 | 1.60 | 19.7 | 23.8 | 22.13 | 1.30 | 21.0 | 24.8 | 23.24 | 1.41 | ||
Eye horizontal diameter (% interorbital width) | 53.7 | 69.5 | 60.57 | 5.51 | 54.22 | 65.59 | 60.14 | 3.42 | 55.6 | 71.1 | 63.13 | 5.82 | ||
Postorbital distance (% HL) | 48.2 | 54.6 | 50.87 | 1.67 | 49.5 | 57.3 | 53.46 | 1.90 | 50.5 | 53.8 | 51.85 | 1.13 | ||
Interorbital width (% HL) | 33.4 | 41.7 | 36.87 | 1.87 | 34.2 | 40.8 | 36.83 | 1.74 | 34.8 | 40.6 | 36.94 | 1.97 | ||
Length of upper jaw (% HL) | 31.3 | 36.6 | 34.73 | 1.31 | 31.3 | 36.1 | 33.70 | 1.28 | 31.5 | 34.4 | 33.30 | 1.09 | ||
Length of lower jaw (% SL) | 11.3 | 13.2 | 12.24 | 0.54 | 11.13 | 12.78 | 11.87 | 0.47 | 11.5 | 12.7 | 12.31 | 0.39 | ||
Length of lower jaw (% HL) | 39.2 | 44.8 | 41.58 | 1.66 | 39.0 | 44.0 | 42.17 | 1.40 | 41.1 | 43.6 | 42.33 | 1.12 | ||
Length of lower jaw (% operculum depth) | 106.7 | 126.7 | 115.38 | 5.81 | 105.95 | 113.54 | 109.67 | 2.42 | 106.6 | 115.8 | 111.08 | 3.18 | ||
Depth of operculum (% HL) | 33.1 | 39.3 | 36.09 | 1.75 | 36.8 | 39.4 | 38.44 | 0.75 | 37.0 | 39.2 | 38.12 | 0.78 | ||
Ratios | ||||||||||||||
Interorbital width/eye horizontal diameter | 1.4 | 2.0 | 1.65 | 0.16 | 1.5 | 1.8 | 1.67 | 0.10 | 1.4 | 1.8 | 1.60 | 0.15 | ||
Snout length/eye horizontal diameter | 1.2 | 1.6 | 1.35 | 0.12 | 1.2 | 1.6 | 1.34 | 0.09 | 1.1 | 1.4 | 1.27 | 0.10 | ||
Head depth at nape/eye diameter | 2.4 | 3.2 | 2.74 | 0.19 | 2.6 | 3.1 | 2.79 | 0.15 | 2.4 | 2.8 | 2.60 | 0.15 | ||
Head length/depth of caudal peduncle | 2.6 | 3.0 | 2.82 | 0.10 | 2.6 | 2.9 | 2.72 | 0.85 | 2.6 | 3.2 | 2.81 | 0.19 | ||
Length of caudal peduncle /depth of caudal peduncle | 1.7 | 2.1 | 1.86 | 0.13 | 1.7 | 2.1 | 1.88 | 0.12 | 1.7 | 2.0 | 1.83 | 0.9 | ||
Length of lower jaw/caudal peduncle depth | 1.1 | 1.3 | 1.17 | 0.06 | 1.0 | 1.2 | 1.15 | 0.07 | 1.1 | 1.3 | 1.19 | 0.06 | ||
Pectoral fin length/pectoral – pelvic-fin origin distance | 0.7 | 0.9 | 0.76 | 0.06 | 0.7 | 0.9 | 0.78 | 0.04 | 0.7 | 0.8 | 0.76 | 0.04 | ||
Predorsal length/head length | 1.8 | 2.0 | 1.95 | 0.05 | 1.9 | 2.1 | 2.01 | 0.04 | 1.9 | 2.1 | 1.99 | 0.05 |
Squalius squalus NMW 49259, 195.5 mm SL, Slovenia: Rizana.
The known range of Squalius janae (Fig. 1) includes Dragonja River (type locality) draining to the west, Pazinčica River that used to flow westwards but at present terminates in a cave at Pazin, and Boljunšćica River that used to flow southwards but now ends in canals in an area that was formerly Čepić Lake. We do not have materials from Raša River that is adjacent to the Boljunšćica and is now connected by canals to the latter. There are no historical samples known to us to decide upon the identity of the native Raša chub.
In rivers of north Istra (Osapska Reka, Rižana, Malinska, and
Mirna) occurs a chub, which was identified by
The data presented above on
the distribution of Squalius chubs in the northern Adriatic
Basin support the assumption by
1. | Lower jaw length less than operculum depth; 5th infraorbital narrow (deeper than wide) or absent | Squalius zrmanjae |
– | Lower jaw length exceeding operculum depth; 5th infraorbital extensive (considerably wider than deep), covering together with large 4th infraorbital most part of outer surface of the musculus dilatatoris operculi | 2 |
2. | Commonly 8½ branched anal-fin rays; pelvic and anal fins red or orange with no black pigment | Squalius cephalus |
– | Commonly 9½ branched anal-fin rays; pelvic and anal fins slightly red, orange or yellow with black pigment of varying intensity | 3 |
3. | Conspicuous silvery tint in life colouration; scales easily lost; iris, pectoral, pelvic and anal fin pigmentation with yellow shades; head length 27–32% SL, lower jaw length exceeding caudal peduncle depth; mouth cleft straight, oblique | Squalius janae |
– | No silvery tint in life colouration, overall colouration with brownish or bronze tones; scales not easily lost; iris, pectoral, pelvic and anal fin pigmentation with reddish or orange shades; head length 26–29% SL, lower jaw length equal to or shorter than caudal peduncle depth; slightly curved mouth cleft | Squalius squalus |
Sincere appreciation goes to Andrej Kapla, Peter Valič, Sašo Mencin, Andrej Piltaver and Ivan Marjanovič who provided valuable help to the first author during his field trips. We also like to thank H. Wilkens and G. Schulze (Zoologisches Museum und Institut, Universität Hamburg), and B. Herzig, E. Mikschi, H. Wellendorf and C. Prenner (Naturhistorisches Museum Wien) for providing materials from the collections under their care that have been used for comparisons. NB and AN have been supported by the Biodiversity Programme of the Russian Academy of Sciences (2009–2010).