Perica Mustafić

A new endemic cyprinid species from the Danube drainage.

Populations of endemic Croatian dace were found to belong to two different species, one of which is first described in this study. Telestes karsticus sp. nov. differed morphologically from Telestes polylepis in the total count of lateral line scales, number of gill rakers and the shape of the posterior margin of the anal fin. Morphological differences were corroborated with mtDNA analyses (with p-distance between T. polylepis and T. karsticus sp. nov. ranging between 3·2 and 4·1%; and the number of substitutions between 37 and 47). The newly described species is geographically very localized. It has been recorded from only four localities around Velika Kapela and Mala Kapela mountains in Croatia.

Occurrence of four-spined Gasterosteus aculeatus in an isolated Croatian river population

An isolated population of the three-spined stickleback Gasterosteus aculeatus in Croatia was found to have a high incidence of specimens either having a fourth dorsal spine or showing remnants of a fourth spine. Juvenile individuals showed a 9.4% incidence of a fourth spine. The population was examined for asymmetry of the skeletal defensive complex in order to determine whether the additional spine could be the result of developmental instability, a response to predation or environmental conditions.

FIRST RECORD OF THREE-SPINED STICKLEBACK (Gasterosteus aculeatus Linnaeus, 1758) IN THE DANUBE BASIN OF CROATIA

The three-spined stickleback (Gasterosteus aculeatus Linaeus, 1758) is a small teleost fish considered to be one of the most widely distributed freshwater fishes in the world (Morrow, 2008). In the northern hemisphere, sticklebacks are absent only along the Arctic coasts of Siberia and North America (Mrakovcic et al., 2006). In Europe they often form highly abundant populations, and in some ecosystems are dominant (Clavero et al., 2009). Three-spined sticklebacks are listed as a species of Least Concern (LC) in the European IUCN Red List (Freyhof et al., 2008). However, freshwater populations in the Mediterranean region have experienced a sharp decline or even local extinction events (Clavero et al., 2009). Despite their wide global distribution, stickleback populations in Croatia are present in a fragmented distribution in isolated rivers of the Adriatic Basin: the Krka River (Visovac Lake), Neretva River catchment and Mirna River catchment on the Istrian peninsula (Mrakovcic et al., 2006; Zanella, 2009; Zanella et FIRST RECORD OF THREE-SPINED STICKLEBACK (Gasterosteus aculeatus Linnaeus, 1758) IN THE DANUBE BASIN OF CROATIA

Threatened fishes of the world: Aulopyge huegelii Heckel, 1842 (Cyprinidae)

Common names: Oštrulja (Cro); Dalmatian Barbelgudgeon (Eng). Conservation status: IUCN Red List: endangered (Crivelli 2005); Croatia: endangered (Mrakovčić et al. 2006). Identification: D III/(6)7-8 (9), V II/5–8, A II/4–6(7), P I/(13)14–15(16), C 19; pharyngeal teeth 4-4. Size to 25 cm, usually to 20 cm. Head extended, pointed and narrow. Two pairs of barbels on the lips. Coloration silvery to yellow-grey, with brown-black specks on dorsal and lateral areas. Generally without scales, some specimens display individual scales. Lateral line wavy. Final dorsal fin ray serrated. The urogenital papilla in females elongated and connected to the anal fin (Heckel and Kner 1858; Guzina 2000). Distribution: Endemic to Dinaric karst rivers and lakes of Croatia and Bosnia and Herzegovina (Vuković and Ivanović 1971; Mrakovčić and Mišetić 1990). Abundance: Previously quite abundant, though the population has been reduced in recent years (Mrakovčić et al. 2006). Habitat and ecology: Prefers lake habitats. Lives in schools that migrate to subterranean waters in the autumn or during droughts (Vuković and Ivanović 1971). Omnivorous (algae, zooplankton and benthic invertebrates). Lives up to 8 years (Kaćanski et al. 1978; Guzina 2000). Reproduction: Spawning begins in April in shallow waters at temperatures of 13–17° C. Fecundity ranges from 1,700 to 17,000 eggs, depending on size and age of female (Aganović 1970; Guzina 2000). Females lay eggs with ovipositor in crevices between rocks and plant roots. Larvae are benthic and solitary and hatch at 6.5 mm (Freyhof 1997; Bless and Riehl 2002). Threats: Aulopyge huegelii is threatened due to its restricted and isolated distribution, dam construction, habitat destruction, water pollution and introduction of alien species (Crivelli 2005; Mrakovčić et al. 2006). Conservation action: Strictly protected in Croatia. Not protected in Bosnia and Herzegovina. Conservation recommendations: Urgent habitat protection with bans on further regulation of the watercourse and water pollution. Population monitoring recommended. Environ Biol Fish (2009) 85:21–22 DOI 10.1007/s10641-009-9445-z

Threatened fishes of the world: Cobitis narentana Karaman, 1928 (Cobitidae)

U radu su navedeni razlozi ugroženosti te ukratko biologija i ekologija neretvanskog vijuna.