A NEW SPECIES OF THE GENUS CHONDROSTOMA AGASSIZ, 1832 (ACTINOPTERYGII, CYPRINIDAE) FROM THE IBERIAN PENINSULA

A new species considered in the past to be included in Chodrostoma lemmingii is described on the basis of genetic and morphological characters. This new species inhabits tributaries of the Jándula River in the Guadalquivir basin, in southern Spain. It is distinguished from C. lemmingii by the following: 1) six to seven branched rays on the dorsal and anal fins, 2) a relatively small number of gill rakers (x = 25.4), 3) a large eye placed very anterior on the head, 4) a high and narrow coronoid process on the dentary, 5) the palatine process of the maxilla posteriorly oriented and, 6) the presence of a diagnostic locus (MDH-A). The range of Chondrostoma oretanum sp. nov. is restricted to the Robledillo and Fresneda Rivers, two small tributaries of the Jándula River in the Guadalquivir basin on the Atlantic slope of the Iberian Peninsula. Following the criteria established by IUCN Red List Categories, we consider C. oretanum to be critically endangered (CR B1 + 2ce).


Introduction
The Iberian Peninsula is home to a great variety of freshwater fishes, including several endemic groups.Cyprinids make up the most diverse group of these freshwater fishes.
In the Iberian Peninsula cyprinids comprise approximately 27 native species (Doadrio, 2001).Ten of these, all endemic, belong to the genus Chondrostoma Agassiz, 1832 (sensu Zardoya & Doadrio, 1998).The high level diversity within this genus seems to have resulted from both vicariant events during the regression of the Sarmatic Sea in the late Miocene, and by the formation of the present-day drainage system during the Pliocene (Zardoya & Doadrio, 1999).
Favoured by its size, the "large species" group shows upstream reproductive dispersal patterns that can be presumed to be migratory movements within the basin (Doadrio, 2001).Due to its dispersal capacity, we hypothesize that the species of this group have a low population structure.In contrast, the "small species" group shows no reproductive dispersal pattern and their ability to colonize new areas is limited by morphological and ecological features.Therefore, we believe species within this group to be characterised by a high population structure.
Chondrostoma lemmingii is a member of the "small species" group that inhabit the south-western basins of the Iberian Peninsula.In recent genetic studies, a high level of genetic divergence has been observed in the populations of C. lemmingii from the Duero and Guadalquivir basins (Carmona et al., 2000).The Duero population, recently described as a new species (Doadrio & Elvira, in press), is thought to have started its differentiation during the Messinian period (6 MYA) (Carmona et al., 2000).On the basis of genetic characters, the differentiation process of the population from the Robledillo River (Guadalquivir basin) was estimated to have begun during the middle Pliocene (3 MYA) (Carmona et al., 2000).
The genetic differentiation observed in the Duero and Robledillo River for these C. lemmingii populations (Carmona et al., 2000) was similar to that observed by Casado (1995) in her morphometric study (Casado, 1995) of the same populations.
The purpose of this study was to describe the specimens from the Robledillo & Fresneda Rivers as a new species of the genus Chondrostoma.Although this species had been previously defined through morphological and genetic analysis, it was, until this present study, undescribed.

Materials and Methods
The description of this new Chondrostoma species is based on twenty adult males and nine adult females.The holotype and a series of paratypes have been deposited in the Museo Nacional de Ciencias Naturales (Spain).Twenty-three morphometric variables were measured.All measurements are in millimetres and were log-transformed for morphometric analysis.
The following abbreviations were used for morphometric and meristic characters: SL, standard length; HL, head length; PrOL, preorbital length; ED, eye diameter; PrDD, predorsal distance; PrPD, prepectoral distance; PrVD, preventral distance; PrAD, preanal distance; CPL, caudal peduncle length; APL, anal peduncle length; PVL, pectoralventral length; VAL, ventral-anal length; DFL, dorsal fin length; DFH, dorsal fin height; PFL, pectoral fin length; VFL, ventral fin length; AFL, anal fin length; AFH, anal fin height; CFL, caudal fin length; BD body depth; BLD, body least depth; LLS, lateral line scales rows; SRA, scale rows above lateral line; SRB, scale rows below lateral line; GR, gill rakers; D, dorsal fin rays; A, anal fin rays; P, pectoral fin rays; V, ventral fin rays; C, caudal fin rays.Only branched fins rays were counted.The osteological characters were studied from clear and stained specimens (Wassersug, 1976) DIAGNOSIS: Differs from all other known species of Chondrostoma by the following combination of characters: six to seven branched rays in the dorsal and anal fins.Six pharyngeal teeth on the left side and five on the right.Eye diameter longer than preorbital distance.Number of gill rakers x = 25.4 (range: 24-27).High and narrow coronoid process on the dentary.The palatine process of the maxilla posteriorly oriented.Presence of one diagnostic locus (MDH-A).
ETYMOLOGY: The species name "oretanum" derives from the old Oretania, an area in South-central Spain that was formerly inhabited by the Oretano people.The range of this species coincides with this area.
DESCRIPTION: D II-III 6-7, A II-III (6-7), P I 12,V I 7,C 19,, SRB x = 5.8 (5-6), GR x = 25.4 (24-27).Abdominal vertebrae 19-20, caudal vertebrae 17-18.Body of Chondrostoma oretanum sp.nov. is more elongated body than that of C. lemmingii.Morphometric characters are given in Tables (1, 2).Minimal body depth is 4.9-3.7 (4.3) times in the caudal peduncle.Minimum body depth is 2.9-2 (2.5) times in the anal peduncle.Maximum body depth is 5.4-4.2(4.8) times in the standard length.Short head, comprising 4.5-4.2(3.8) times the standard length.Eye placed anterior on the head, its diameter is proportionally bigger than in C. lemmingii.Preorbital distance shorter than eye diameter, reaching 1.5-1 (1.2) times the eye diameter (Table 3).Ventral fin is inserted at or before the origin of the dorsal fin, on the same axis.Preventral length is 1-1.1 (1) times the predorsal length.Fin  nov.are scarce and are restricted to the Robledillo and Fresneda Rivers, two small tributaries of the Jándula River in the Guadalquivir basin (Fig. 3).The Jándula River is the only known locality of another endemic cyprinid fish, Squalius palaciosi (see Doadrio, 1980).CONSERVATION: The Robledillo and Fresneda Rivers flow through an area of well-preserved Mediterranean forest that is of enormous environmental value.Recently, however, the Public River Administration built a small dam with a hydrologi-cal monitoring station that has had serious impacts on the Robledillo River.In addition, two small reservoirs inhabited by exotic fishes have also severely affected the Fresneda River.The impacts on these rivers have drastically reduced populations and C. oretanum sp.nov.Following the criteria established by IUCN Red List Categories, we consider C. oretanum to be critically endangered (CR B1 + 2ce).
eyes are placed in a very anterior position in the head.These characters were also found by Casado (1995) in a morphological study comprising several populations of C. lemmingii.Males from the Robledillo River population (females were not studied due to absence of material) were differentiated morphologically in a multivariate analysis of 22 morphometric variables using the Burnaby's method to correct for size effects (Fig. 4) (Casado, 1995).In addition, C. oretanum sp.nov.from the Robledillo River had significantly fewer gill rakers than did the C. lemmingii population from the Bembezar River (n=28).Both the aforementioned rivers are in the Guadalquivir basin (Table 4).Moreover, using molecular markers, C. oretanum sp.nov.showed a diagnostic locus (MDH-A) and clear differences in allele frequencies at other loci (Carmona et al., 2000).There was a mean sequence divergence of 4.25% (uncorrected p distance from the complete cytochrome b nucleotide sequence) between C. oretanum sp.nov.and C. lemmingii (Carmona et al., 2000).The genetic differentiation of C. oretanum sp.nov.respect to other C. lemmingii populations is similar to that found between other species of the genus Chondrostoma.For instance, one diagnostic locus separates C. polylepis from C. willkommii (Coelho, 1992;Coelho et al., 1997) and C. nasus (L.1758) from C. vardarense Karaman, 1928(Gollmann et al., 1997) whilst two diagnostic loci separate C. polylepis and C. willkommii from C. duriense (Coelho, 1992).Although the allele frequencies of C. lemmingii and C. arcasii differ greatly, no diagnostic loci were found for this species pair (Carmona et al., 2000).

AKNOWLEDGEMENTS
This study was financed by projects REM2001-0662/G10 and 07M/0109/02.We thank J. Cubo, I. Doadrio Jr., A. Doadrio, P. Garzón, M. González, F. Lerma and G. González-Carmona for their assistance with field collections.We are grateful to M. García-París for his suggestions and improving some of the English text.Mr. James Watkins further revised the English text.The Regional Administration (Junta de Castilla-La Mancha) provided the necessary permits to collect the fish samples.
(c)Sociedad de Amigos del Museo Nacional de Ciencias Naturales y Consejo Superior de Investigaciones Científicas Licencia Creative Commons 3.0 España (by-nc) http://graellsia.revistas.csic.eswarrants separating them into separate species.No available name can be assigned to the Robledillo population, and therefore, we have chosen to call this population Chondrostoma oretanum sp.nov.

Table 4 .
-Summary of diagnostic characters of C. oretanum sp.nov based on a sample of 29 specimens.The C. lemmingii samlple is based on 69 individuals from the Guadiana basin.For gill rakers a sample of 28 individuals from Bembezar River in Guadalquivir basin was used.Tabla 4.-Resumen de caracteres diagnósticos de C. oretanum sp.nov, sobre una muestra de 29 individuos.La muestra de C. lemmingii consiste en 69 individuos de la cuenca del Guadiana.Para la comparación de las branquiespinas se consideró la muestra de 28 individuos del río Bembézar en la cuenca del Guadalquivir.