Micha³ Nowak, W³odzimierz Popek, Ewa Dr¹g-Kozak, Piotr Epler. Department of Ichthyobiology and Fisheries, Agricultural University of Kraków, Poland - PDF

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Arch. Pol. Fish. Archives of Polish Fisheries Vol. 16 Fasc MORPHOLOGY OF THE COMMON GUDGEON, GOBIO GOBIO (L.) SENSU LATO, FROM THE VISTULA RIVER DRAINAGE IN THE CONTEXT OF RECENT LITERATURE

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Arch. Pol. Fish. Archives of Polish Fisheries Vol. 16 Fasc MORPHOLOGY OF THE COMMON GUDGEON, GOBIO GOBIO (L.) SENSU LATO, FROM THE VISTULA RIVER DRAINAGE IN THE CONTEXT OF RECENT LITERATURE DATA (TELEOSTEI: CYPRINIDAE) Micha³ Nowak, W³odzimierz Popek, Ewa Dr¹g-Kozak, Piotr Epler Department of Ichthyobiology and Fisheries, Agricultural University of Kraków, Poland ABSTRACT. The common gudgeon Gobio gobio (L.) is considered to be highly variable and to show very good adaptability to local environmental conditions. The most recent studies show that the traditional notion of the G. gobio species covers a number of highly similar but distinct species that can be distinguished based on detailed analysis of morphometric characters. This work presents the results of biometric studies on common gudgeons from two small rivers in the Vistula River drainage. The study has shown several biometric differences between the analyzed populations. Whether the two populations of the common gudgeon represent distinct species or are only evidence of intraspecific variation will be clear once the required comparative material has been gathered. Therefore, in accordance with the international trend, these populations should be treated as Gobio gobio (L.) sensu lato (= G. gobio (L.) complex). Key words: COMMON GUDGEON, CYPRINIDAE, GOBIO GOBIO, MORPHOMETRICS, SYSTEMATICS, VISTULA RIVER DRAINAGE INTRODUCTION The genus Gobio Cuvier, 1816 belongs to the subfamily Gobioninae of the family Cyprinidae. Initially it included all of the Euro-Asian gudgeons, which are now divided into several distinct genera (Naseka 1996, Bogutskaya and Naseka 2004, Kottelat and Freyhof 2007). It has been established (e.g. G¹sowska 1962, Bia³okoz 2000 and many others) that Poland is inhabited by five species of the subfamily Gobioninae, belonging to three genera: (1) Gobio Cuvier, 1816, common gudgeon, Gobio gobio (L.), (2) Romanogobio Bãnãrescu, 1961, white-finned gudgeon, Romanogobio albipinnatus (Lukasch), Kessler s gudgeon (sand gudgeon), Romanogobio kesslerii (Dyb.), CORRESPONDING AUTHOR: Micha³ Nowak, Katedra Ichtiobiologii i Rybactwa, Kraków, ul. Prof. Spiczakowa 6, Tel./Fax: (48 12) , (48 12) ; 38 M. NOWAK et al. Danubian longbarbel gudgeon (stone gudgeon), Romanogobio uranoscopus (Agassiz), and (3) Pseudorasbora Bleeker, 1860, topmouth gudgeon (stone moroko), Pseudorasbora parva (Temminck and Schlegel). The incidence of stone gudgeon was questioned by Rolik (1959), and so far there has been no clear evidence that this species lives in Polish waters. Until recently, the common gudgeon was considered a widespread, pan-palearctic species with many subspecies and local forms in different environmental conditions (Berg 1949, Bãnãrescu et al. 1999, Kottelat and Persat 2005, Vasil eva et al. 2004, 2005, Vasil eva and Kuga 2005, Naseka et al. 2006). However, the most recent studies have shown immense morphological and osteological variation in different populations of G. gobio (Vasil eva et al. 2004, 2005, Kottelat and Persat 2005, Naseka et al. 2005, 2006). Therefore, many of the former subspecies and local forms are now considered to be distinct species (for a review, see: Naseka et al. 2006, Kottelat and Freyhof 2007). Meanwhile, Kottelat and Persat (2005) redefined the species G. gobio (L.) sensu stricto, and designated a neotype (terra typica: Sieg River, Eitorf, Rhine drainage, Germany). Today, the common gudgeon is most often referred to as G. gobio sensu lato (G. gobio complex). Previous publications on the systematics of the common gudgeon in Poland distinguished three subspecies: the nominative G. gobio gobio (L.) in the Vistula and Oder River drainage (Rolik 1965), the Danubian G. gobio obtusirostris (Val.) in the Danube River drainage: in the Czarna Orawa (Balon 1964, Balon and Holèik 1964; Polish name kie³b dunajski proposed by Rembiszewski and Rolik, 1975) and Prut rivers (Oliva 1962), and the Dniester gudgeon G. gobio sarmaticus (Berg) in the Strwi¹ River of the Dniester drainage (Rolik 1967; Polish name kie³b dniestrzañski proposed by Rembiszewski and Rolik, 1975). Most authors have ignored the subspecific variation of the common gudgeon, treating all the populations as G. gobio (e.g. G¹sowska 1962, Rembiszewski 1964, Skóra and W³odek 1966, 1971). Much of the misunderstandings in the systematics of gudgeons stemmed from the different measurement methods used in Western and Eastern Europe (Kottelat and Persat 2005, Naseka et al. 2006, Kottelat and Freyhof 2007). The measurements used today (Naseka and Freyhof 2004, Freyhof and Naseka 2005, Kottelat and Persat 2005, Naseka et al. 2005, 2006, Kottelat and Freyhof 2007) are based on the system by Hubbs and Lagler (1958). MORPHOLOGY OF THE COMMON GUDGEON, GOBIO GOBIO (L.) The present study contributes to the exploration of the morphological variation in the common gudgeon in the Vistula River drainage, with regard to current European trends and changes that have recently occurred in the systematics of the Gobio genus. MATERIAL AND METHODS A total of 118 gudgeon specimens of both sexes were investigated. Sixty-five specimens were caught from the Rudawa River (a left-bank tributary of the Vistula River) at the Fishery Experimental Station of the Department of Ichthyobiology and Fisheries, Agricultural University of Kraków. Fifty-three specimens were caught from the Silnica River (a tributary of the Bobrza River in the drainage of the Czarna Nida River, a left-bank tributary of the Vistula River) in Kielce (Fig. 1). Fish were harvested using a lift net, anesthetized at the harvesting site by bathing in an aqueous extract of Propiscin (Etomidate), and fixed in 4% formalin. Fig. 1. Area of the presented study: 1 Rudawa River in Kraków; 2 Silnica River in Kielce. 40 M. NOWAK et al. All the gudgeons were analyzed for 28 morphometric characters and 10 meristic characters according to the design proposed by Naseka and Freyhof (2004), based on the method by Hubbs and Lagler (1958), which is proposed to be an international one (Kottelat and Freyhof 2007). All the measurements were performed by the point-to-point method, using a caliper to the nearest 0.1 mm. Abbreviations used: TL total length; SL standard length, distance from the tip of the snout to the end of hypural complex, point determined by bending back the caudal fin in either direction, which reveals a clear edge; HL head length, distance from the tip of the snout to the posteriormost point of the opercular membrane; ad predorsal length; av prepelvic length; aa preanal length; P-V distance between the bases of the pectoral and pelvic fins; V-A distance between the bases of the pelvic and anal fins; V-an distance between the end of the pelvic-fin base and anus; an-a distance between the anus and anteriormost point of the anal-fin base; pl length of caudal peduncle, measured from the vertical line running through the end of the anal-fin base to the end of the hypural complex, measured along the longer body axis; H maximum body depth, measured in advance of the dorsal fin; h minimum depth of the caudal peduncle; ih width of the body in advance of the dorsal fin; ih width of the caudal peduncle, taken at the insertion of the anal fin; lp, lv length, consecutively, of the pectoral and pelvic fins, measured from the base of the first ray to tip of the longest ray; ld, la length, consecutively, of the dorsal and anal-fin bases; hd, ha depth consecutively, of the dorsal and anal fins, measured from the base to the tip of the longest fin-ray; r snout length; po postorbital length, measured from the posterior osseous margin of the orbit to the posteriormost point of the opercular membrane; o horizontal eye diameter, distance between the osseous orbital margin; io interorbital width, the least distance between fleshy margins of the orbits; ic head width, taken at the opercles; hc head depth at the nape; lb length of the barbells. Following characters: SL, HL, and po were not measured according to the Pravdin s (1966) scheme, which is commonly used in Eastern Europe, but according to the scheme by Hubbs and Lagler (1958). The number of rays in the dorsal and anal fin were determined visually without X-ray, contrary to the method by Naseka and Freyhof (2004). The last two branched rays, set on a common pterygiophore, were counted as 1. Along the lateral line, all the perforated scales were counted as scales on the body (to the end of the hypural complex) or scales on the caudal fin. These two numbers were separated using a + sign. MORPHOLOGY OF THE COMMON GUDGEON, GOBIO GOBIO (L.) Scales from the lateral line to the dorsum and from the lateral line to the ventral edge were counted in longitudinal rows. The extreme dorsal and ventral rows were counted as. In addition, circumpeduncular rows (horizontal rows of scales around the caudal peduncle) were counted at the lowest part of the caudal peduncle. The scale pattern on the belly was characterized according to a scheme presented by Naseka et al. (2006), as illustrated in Fig. 2. The results of the morphometric measurements were subjected to basic statistical analysis using the Statsoft Statistica 7.1. The highest and lowest values of the analyzed characters, arithmetic means, and standard deviations were determined; both samples Fig. 2. Scale pattern on belly of the gudgeons. Numbers 1-3 indicate character states (according to Naseka et al. (2006), original drawing). 42 M. NOWAK et al. were subjected to Student s t-test for independent samples; and each sample was compared separately with the neotype values (Kottelat and Persat 2005) using Student s t-test for single samples. In both cases, Pearson s coefficients of correlation (r) were determined between the main morphometric characters and body length (SL). RESULTS Specimens of similar size were studied from both populations (SL of mm for gudgeons from the Rudawa River and mm for gudgeons from the Silnica River; differences were not significant, P 0.05). The populations did not differ significantly in terms of meristic characters (Table 1). TABLE 1 Meristic characters in gudgeons from the Rudawa and Silnica Rivers. Number of branched rays in dorsal and anal fins, same as number of horizontal rows of scales, were given without sign, i.e. value 7 branched dorsal-fin rays in the table refers to 7 in the text Rudawa River Silnica River Character range mean S.D. range mean S.D. Number of unbranched rays in dorsal fin Number of branched rays in dorsal fin Number of unbranched rays in anal fin Number of branched rays in anal fin Number of scales in lateral row (total) Rows of scales above lateral line Rows of scales below lateral line Circumpeduncular rows of scales In the dorsal fin they had 3 unbranched (1 fish from the Rudawa River had 2) and 7 branched rays (all fish). In the anal fin they had 3 unbranched (11 fish from the Rudawa River and 2 fish from the Silnica River had 2) and 6 branched rays (1 fish from the Rudawa River and 1 fish from the Silnica River had 5 ). The lateral line of gudgeons from the Rudawa River contained scales on the body and 1-3 scales in the caudal fin (39+2 on average). Gudgeons from the Silnica River had scales on the body and 1-3 scales on the caudal fin (39+2 on average). In all the specimens, there were (usually 13-14) circumpeduncular rows around the caudal peduncle. There were 5-6 horizontal rows of scales between the lateral line and the dorsum, MORPHOLOGY OF THE COMMON GUDGEON, GOBIO GOBIO (L.) and 3-4 horizontal rows of scales between the lateral line and the ventral edge. The most common pattern was 6 rows of scales above the lateral line and 4 below. The throat was essentially scaleless. In the Rudawa River gudgeons, the scale cover reached the anterior end of the pectoral fin base, corresponding to point 2 on the scale of Naseka et al. (2006), or covered part of the throat area between the gill covers, corresponding to point 3. In the Silnica River gudgeons, a narrow strip of scales usually reached the posterior end of the pectoral fin base (point 1) or slightly farther (between points 1 and 2) (Fig. 2). The scales covering the belly and throat of the Rudawa River specimens were clearly massive and large, unlike the fine scales on the belly of the Silnica River specimens. Pectoral fins were large and accounted for an average of 85% and 78% of the P-V length in Rudawa and Silnica River gudgeons, respectively (Table 1). Pelvic fins were considerably smaller and usually covered the anus (sometimes only reaching the anus), a pattern that was more frequent in the Rudawa River specimens. In the gudgeons from the Rudawa River, their length accounted for an average of 79% of the V-A length and for 74% of the length in the gudgeons from Silnica River. In terms of the Pearson s correlation, 13 of all 26 characters were found to be significantly (P 0.05) dependent on SL in gudgeons from the Rudawa River and 9 of all 26 in gudgeons from the Silnica River. The following characters from the first sample were found to be the strongest positively length-dependent: H/SL (r = 0.85); ih/sl (r = 0.71); r/hl (r = 0.63). The strongest negative correlation with SL was found in hd/sl (r = -0.60) and o/sl (r = -0.59). The body proportions of gudgeons from the Silnica River showed a weaker dependence on SL. As for gudgeons from the Rudawa River, the strongest positive dependence on SL was noted in the H/SL ratio (r = 0.38) and the strongest negative correlation with SL was observed for the following characters: o/hl (r = -0.69); pl/sl (r = -0.56); hd/sl (r = -0.40). DISCUSSION During the comparison with the neotype (Kottelat and Persat 2005), the following observations were made (Table 2). Gudgeons from the Rudawa River differed the most from the neotype in body depth (19.0% vs 21.7% SL, t = ), head length (25.5% vs 27.1% SL, t = ), and snout length (39.3% vs 43.0% HL, t = ). In this 44 M. NOWAK et al. respect, specimens from the Silnica River were much more similar to the neotype (t equal to: -2.52, and -4.02, respectively), although the differences remained significant (P 0.05). However, the Silnica River specimens differed the most from the neotype in caudal peduncle depth (8.2% vs 9.5% SL, t = ; like specimens from the Rudawa River, t = -7.10), anal fin height (14.9% vs 16.5% SL, t = 14.83), pectoral fin length (19.1% vs 20.8% SL, t = 10.68), and head depth (62.2% vs 59.0% HL, t = 10.33). Gudgeons from the Rudawa River showed a significant resemblance in terms of prepelvic length only (48.9% vs 49.2% SL, t = -1.78), and specimens from the Silnica River in terms of caudal peduncle length (21.8% vs 21.9% SL, t = -0.63) and eye diameter (22.3% vs 22.0% HL, t = 1.69). The Rudawa River population differed significantly (P 0.05) from the typical specimen in 15 out of the 16 body proportions analyzed (almost 94%), and gudgeons from the Silnica River in 14 out of 16 (87.5%). The analyzed populations differed significantly (P 0.05) in 19 out of 26 body proportions (73%) (Table 2). The differences were only non-significant for predorsal and preanal length (t = 0.14 and -0.53, respectively), caudal peduncle length (t = -1.91), caudal peduncle width (t = 0.93), anal-fin base length (t = 1.96), postorbital distance (t = 1.97), and head depth (t = -1.37). Gudgeons of both populations were riverine, so pointed differences cannot be explained in terms of traditional lotic and lentic ecological forms (Bãnãrescu 1954, Bãnãrescu et al. 1999), as Rolik (1965) did in case of several populations from the Vistula drainage. Besides, this differentiation has been already thoroughly criticized by Kottelat and Persat (2005) as generally unclear. Furthermore, the recent publication by Kottelat and Freyhof (2007), which considers many traditional subspecies or local forms to be valid distinct species (e.g. Gobio carpathicus, G. obtusirostris, and G. sarmaticus already mentioned herein), suggests that the usage of the name G. gobio is still confusing, and probably further distinct species will yet be recognized. Unfortunately, previous literature data (e.g. Rolik 1965, 1967, Skóra and W³odek 1966, 1971 and many others), as it was already stressed, were based on different and often incomparable methods of measurement, so they cannot be used in the current study. In this context, the differences identified between the analyzed populations should be taken as a starting point for further investigations. MORPHOLOGY OF THE COMMON GUDGEON, GOBIO GOBIO (L.) TABLE 2 Comparison of morphological characters in gudgeons from the Rudawa, Silnica Rivers and neotype (Kottelat and Persat 2005). For character abbreviations, see text, SD standard deviation Rudawa River Silnica River Character mean range SD mean range S.D. neotype TL, mm 93.2 a a SL, mm 76.6 a a In per cent (%) of SL HL 25.5 a b c ad 47.6 a a b av 48.9 a b a aa 70.5 a a b P-V 24.1 a a V-A 21.6 a b V-an 9.3 a b an-a 8.2 a b pl 21.3 a a b H 19.0 a b c h 8.7 a b c ih 15.6 a b c ih 7.9 a a ld 13.0 a b hd 21.3 a b c la 8.3 a a ha 15.9 a b c lp 20.5 a b c lv 17.0 a b c In per cent (%) of HL r 39.3 a b c po 44.1 a a o 23.4 a b b io 30.7 a b c hc 61.5 a a c ic 58.4 a b lb 27.5 a b Values with a different letter index in the same row differ significantly statistically (test t, P 0.05) CONCLUSIONS The presented results show that different populations of the so-called Gobio gobio from the drainage of one river differ considerably in terms of morphometric characters. At this stage of the research, the analyzed populations of common gudgeon cannot be classified conclusively because of the lack of accurate analysis in different parts of 46 M. NOWAK et al. Poland, the often incomplete characteristics provided in publications, and the use of different (and often unspecified) measurement methods by the authors. At this point, it could be stated that they confer G. gobio sensu stricto, as it is redescribed by Kottelat and Persat (2005), but nothing more. Because of the differences shown in morphological structure, until more comparative material is gathered it seems justified to treat the common gudgeon populations from the Vistula River drainage with a modicum of caution and to regard them as Gobio gobio (L.) sensu lato (G. gobio (L.) complex), as is the case of Gobio gudgeons from the rivers of Crimea classified by Vasil eva et al. (2004, 2005), Vasil eva and Kuga (2005) and Naseka et al. (2005). ACKNOWLEDGMENTS The authors want to express their appreciation to the anonymous Reviewer for his valuable comments on an early version of the manuscript. REFERENCES Balon E Inventory and ecological characteristic of freshwater agnathans and fishes of Poland Pol. Arch. Hydrobiol. 12: (in Polish). Balon E., Holèik J Some new lampreys and fishes in Poland from Danube River drainage (Czarna Orawa) Fragm. Faun. 11: (in Polish). Bãnãrescu P Biometrische und systematische Studien an Gobio gobio aus Rumänien Vìstn. Èsl. Spol. Zool. 18: Bãnãrescu P., Šoriè V., Economidis P Gobio gobio (Linnaeus, 1759) In: The Freshwater Fishes of Europe. Vol. 5/I. Cyprinidae 2. Rhodeus to Capoeta. (Ed.) P. Bãnãrescu, Aula, Wiebelsheim: Berg L.S Ryby presnych vod SSSR i sapredel nych stron Izdatel stvo Akademii Nauk SSSR, Moskwa-Leningrad: Bia³okoz W Common gudgeon Gobio (gobio) gobio, Sand gudgeon Gobio (Romanogobio) kessleri, White-fined gudgeon Gobio (Romanogobio) albipinnatus In: Freshwater fishes of Poland (Ed.) M. Bryliñska PWN, Warsaw: (in Polish). Bogutskaya N.G., Naseka A.M Katalog besèelustnych i ryb presnych i solonovatych vod Rossii s nomenklaturnymi i taksonomièeskimi kommentarirami KMK Scientific Press, Moskva: Freyhof J., Naseka A.M Gobio delyamurei, a new gudgeon from Crimea, Ukraine (Teleostei: Cyprinidae) Ichthyol. Explor. Freshwat. 16: G¹sowska M Agnathans and fishes Cyclostomi et Pisces. Handbook of vertebrates of Poland. Part I Wyd. PWN, Warszawa 240 p. (in Polish). Kottelat M., Freyhof J Handbook of European Freshwa
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