DESCRIPTION OF THREE NEW SPECIES OF THE GENUS ACHONDROSTOMA ROBALO, ALMADA, LEVI & DOADRIO, 2007 (ACTINOPTERYGII, LEUCISCIDAE) IN THE IBERIAN PENINSULA

Introduction[Up]

The Iberian Peninsula harbours a large number of local freshwater fish endemisms, mainly belonging to the family Leuciscidae. Close to 80% of the species of this family inhabiting the Iberian Peninsula are local endemisms (‍Doadrio, 2002; ‍Doadrio et al., 2011). A salient feature of the Iberian freshwater fish fauna is the presence of few lineages with numerous species per lineage. This is the case for the lineage corresponding to the former genus Chondrostoma, which is comprised of more than 30 species widespread throughout Europe and near Asia, of which 15 are endemic of the Iberian Peninsula (‍Doadrio & Carmona, 2003a; ‍Coelho et al., 2005; ‍Robalo et al., 2005a, ‍2005b; ‍Doadrio et al., 2011). In a revision of the genus Chondrostoma, Robalo et al. (‍2007) identified six major clades well supported both by morphological and genetic characters, and recognized five new genera. Three of these genera are Iberian endemics (Achondrostoma, Iberochondrostoma and Pseudochondrostoma) while a fourth (Parachondrostoma) is mostly Iberian (eastern Spain) but with a single species distributed mainly in France (P. toxostoma). These lineagesseparated approximately 11 MYA and most radiation occurred in the Iberian Peninsula (‍Doadrio & Carmona, 2004; ‍Robalo et al., 2007).

The genera Parachondrostoma and Pseudochondrostoma contain large-sized potamodromous species (‍Doadrio, 2002). For this reason, their populations tend to be more uniform and less genetically structured. In contrast, species of the Iberochondrostoma and Achondrostoma genera are small sedentary fish and thus different sections of a single drainage show genetic differentiation (‍Doadrio, 2002; ‍Corral-Lou et al., 2021). This situation has complicated the taxonomy of these genera, and new species continue to be described (I. lusitanicum ‍Collares-Pereira, 1980; I. oretanum ‍Doadrio & Carmona, 2003b; I. almacai ‍Coelho, Mesquita & Collares-Pereira, 2005; A. oligolepis ‍Robalo, Doadrio, Almada & Kottelat, 2005; A. occidentale ‍Robalo, Almada, Sousa, Moreira & Doadrio, 2005; A. salmantinum ‍Doadrio & Elvira, 2007; I. olisiponense ‍Gante, Santos & Alves, 2007) including some awaiting formal description (‍Robalo et al., 2007).

Taxonomic problems in the genus Achondrostoma had already been detected in a molecular study by Zardoya & Doadrio (‍1998). These authors found that the two species recognized at the time in this clade, A. arcasii and A. oligolepis (= C. macrolepidotum) did not form reciprocally monophyletic groups. Some populations of A. arcasii were closer to A. oligolepis, indicating that A. arcasii was a polyphyletic entity that required further examination. In subsequent phylogenetic analyses of fishes of the genus Achondrostoma (‍Robalo et al., 2006, ‍2007), the authors were repeatedly faced with the same problem, and A. arcasii was noted to comprise at least six different lineages that had been grouped under the same name (‍Doadrio et al., 2021). Moreover, these lineages occupy distinct geographical areas and the divergence time among them has been estimated to vary from 2 to 7 MYA, depending on the pair of clades compared (‍Robalo et al., 2006, ‍2007).

In this paper, three new species are described corresponding to populations previously ascribed to A. arcasii from Western Spain (Tajo and Duero drainages), Northwestern Duero Drainage (Esla sub-basin) and Central-Eastern Duero Drainage. Besides being geographically distant, these three locations present high morphological and genetic differentiation in their A. arcasii populations.

Material and methods[Up]

The morphometric and meristic study of Achondrostoma arcasii was based on the analysis of 56 individuals from Western Spain: 26 from Alagón River (Tajo Drainage), El Tornadizo, Salamanca and 30 from the Corneja River (Duero Drainage), San Bartolomé de Corneja, Ávila. Ninety-nine individuals from Central-Eastern Duero: 32 from Cega River Lastras de Cuellar, Segovia; 21 from Pedro River, Cuevas de Ayllón, Soria, 20 from Voltoya River, 6 individuals from Labajos, Ávila and 14 individuals from Urraca Miguel, Ávila and 26 from Odra River, Villasendino, Burgos. Thirty-seven individuals from Northwestern Duero: 21 from Tera River, Ribadelago, Zamora and 16 of Peces and Garandones lakes, Galende, Zamora. One hundred eighteen individuals of A. arcasii specimens from Mediterranean basin: 60 from Ebro Drainage: 25 from the Zirauntza River, Egino, Alava and 35 from the Queiles River, Tulebras, Navarra; 28 individuals from Mijares Drainage, Mijares River, Olba, Teruel and 30 from Turia Drainage, Alfambra River, Aguilar de Alfambra (Teruel) and 2 syntypes deposited in the collections of the Naturhistorisches Museum Wien NMW 50646:1,5 from the Queiles River, Tudela. Thus, a total of 310 specimens of A. arcasii: 56 from Western Spain; 99 from Central-Eastern Duero; 37 from Northwestern Duero and 118 from Mediterranean basin were studied to the morphometric analyses.

The material analyzed to the osteological study is showed in Appendix 1.

Holotypes and paratype series of the three new species have been deposited in the Museo Nacional de Ciencias Naturales (MNCN-CSIC Spain).

Morphology

Twenty-three morphometric measurements (in mm) and ten meristic variables were recorded from digital photographs using TpsDig v.1.4 (‍Rohlf, 2003). The following abbreviations were used for morphometric and meristic characters: TL, total length; SL, standard length; HL, head length; HH, head high; PrOL, preorbital length; ED, eye diameter; PsOL, postorbital length, IO, interorbital distance; PrDD, predorsal distance; PrPD, prepectoral distance; PrVD, preventral distance; PrAD, preanal distance; CPL, caudal peduncle length; APL, anal peduncle length; DFL, dorsal fin length; DHL, dorsal fin height; PFL, pectoral fin length; VFL, ventral fin length; AFL, anal fin length; AHL, anal fin height; CFL, caudal fin length; BD body depth; BLD body least depth; LLS, lateral line scale rows; SRA, scale rows above lateral line; SRB, scale rows below lateral line; D, dorsal fin rays; A, anal fin rays; P, pectoral fin rays; V, ventral fin rays; C, caudal fin rays; RPT, right pharyngeal teeth; LPT, left pharyngeal teeth; Vr, Vertebrae. After constructing the measurement matrix, Burnaby’s method was used to correct for size effect. The Burnaby method removes the effects of a within population size-factor from between-group morphometric analyses through an orthogonal projection procedure (‍Burnaby, 1966). All analyses were conducted with the corrected matrix. Morphometric and meristiccharacters were analysed independently. To identify the variables that contributed most to the variation among populations, one principal component analyses (PCA) were performed using the covariance matrix for morphometric characters. Statistical analyses were carried out using PAST software (‍Hammer et al., 2001).

Osteological characteristics were investigated through of cleared and stained specimens (‍Taylor, 1967); X-ray computer tomography (CT) scan and digital dissection using VGStudio MAX v2.2 (Volume Graphics, http://www.volumegraphics.com) and dry skeletons preserved in the MNCN collections.

Additionally, we increased the samples of pharyngeal teeth through dissection of preserved alcohol specimens (Appendix 1).

Due to osteological differences found in the wide of the skull, we took the minimum interorbital distance to a subset of n = 78 with a digital caliper of 0.1 mm of precision.

Institutional acronyms: MNCN Museo Nacional de Ciencias Naturales; NMW Naturhistorischen Museum Wien.

Genetic analyses

141 specimens from different populations of Achondrostoma arcasii, 44 specimens of A. oligolepis, 17 specimens A. occidentale and 2 specimens of A. salmantinum were analysed throughout their geographic ranges (Appendix 1). In these analyses, we examined sequences of the entire mitochondrial cytochrome b gene (MT-CYB), using previously published data (‍Robalo et al., 2006, ‍Doadrio et al., 2021) deposited in GenBank and new sequences data obtained from the DNA and Tissue Collection at the National Museum of Natural Sciences of Madrid (MNCN–CSIC). The new sequences data has been deposited in the GenBank data base (Appendix 2).

Total genomic DNA was extracted from fin-clip tissue using the Qiagen DNeasy® Blood and Tissue Kit (Qiagen, Inc., Valencia, CA, USA), following the manufacturer’s protocol. For each specimen, the complete MT-CYB region (1140 bp) was amplified. Primers and protocols used for PCR for MT-CYB amplification followed Corral-Lou et al. (‍2019). PCR products were purified with ExoSAP-IT (USB Cleveland, OH, USA) and then sequenced on a 3730xl DNA Analyzer by Macrogen Europe Inc. (http://www.macrogen.com). Two different phylogenetic analyses were performed using Bayesian inference (BI) implemented in MrBayes v. 3.2 (‍Ronquist et al., 2012) and Maximum Likelihood implemented in the IQ-tree online web server from the Vienna University (http://iqtree.cibiv.univie.ac.at/; ‍Trifinopoulus et al., 2016). ModelFinder, implemented in the previous IQ-Tree web server (‍Kalyaanamoorthy et al., 2017) and the Bayesian Information Criterion (‍Schwarz, 1978) were used to estimate the evolutionary model that best fitted thedata. The selected evolutionary model was TN+F+G4. The Bayesian analysis was performed with two simultaneous independent runs each with four Markov chain Monte Carlo (MCMC), which were run for 5 × 10⁷ generations. The first 25% of generations were removed as burn-in. Posterior probability (pp) values were used to assess the reliability of the phylogenetic hypothesis. The accuracy of the Maximum Likelihood phylogeny was evaluated with the UltraFast Bootstrap method (1000 replicates) (‍Minh et al., 2013). Two sequences of Achondrostoma salmantinum were used as outgroup (Appendix 2). Uncorrected p-distances among Achondrostoma populations were calculated for the MT-CYB gene using Mega X (‍Kumar et al., 2018). Only nodes with a posterior probability (pp) of 0.95 and bootstrap of 70, or higher, in at least one analysis are considered as statistically supported.

To assess the phylogeographic structure among the haplotypes which are present in the morphological groups studied (Western Spain, Central-Eastern Duero, Northwestern Duero and Mediterranean drainages) and in the species of the genus Achondrostoma, we reconstructed haplotype networks using the Median-joining algorithm (‍Bandelt et al., 1999) as implemented in the program PopArt (‍Leigh & Bryant, 2015).

Results and discussion [Up]

Comparison of morphology among populations

Due to the sexual dimorphism of Achondrostoma (‍Rojo & Ramos, 1987), we removed fin size to subsequent morphological analyses.

The principal component analysis divided the populations of A. arcasii into three groups corresponding to populations of a) Mediterranean basin (Ebro, Mijares and Turia drainages), b) Western Spain that included Alagón River in the Tajo Drainage and Corneja River in the Duero Drainage and c) Central-Eastern and Northwestern Duero that included all the rivers from Duero Drainage except for the Corneja River. The populations of the Central-Eastern and Northwestern Duero were considered in the same group due to the overlapping of their individuals in the principal component analyses (Fig. 1).

Nevertheless, the population of the Northwestern Duero could be discriminated from the other studied populations by the lesser number of scales on the body. The eigenvalues of the three first principal components, with the Burnaby-corrected matrix, explained most of the variance (Appendix 3). The highest values for eigenvectors and, consequently, the variables that contributed most to the ordination in the PCA were: preorbital length, postorbital length, body depth and anal peduncle length (Appendix 3).

The Mediterranean populations exhibited smaller preorbital length with respect to the other studied populations and values of the postorbital length similar to those from Western Spain populations and therefore the ratio PsOL/PrOL in Mediterranean populations was the highest (Appendix 4; Fig. 2). The body depth was smaller in Western Spain than in the other studied populations, the ratio SL/BD was the highest (Appendix 3; Fig. 2) and the ratio BD/BLD the lowest (Appendix 4; Fig. 2). The Mediterranean populations had a caudal peduncle short and high and had the greater values to body least depth and lesser to the length of the anal peduncle and therefore the ratio APL/BLD, was the smallest (Appendix 4; Fig. 2). The head of the populations from Central-Eastern Duero was smaller and had the highest values in proportion to the standard length (Appendix 4; Fig.2).

The number of scales in the lateral line was lesser in populations of the Mediterranean drainages (x̄ = 41.1 37-43 n = 63) and in those of the Northwestern Duero, mainly Esla sub-basin (x̄ = 40.9 38-44 n = 36) than in the populatons of Western Spain (x̄ = 45.9 43-49 n = 66) and Central-Eastern Duero Drainage (x̄ = 45.1 43-48 n = 99) (Fig. 3). Scales number above of lateral line was lesser in Northwestern Duero (x̄ = 5.8 5-6 n = 36) than in the other populations from Mediterranean drainages (x̄ = 7.1 6-8 n = 63); Western Spain (x̄ = 6.8 6-7 n = 66) and Central-Eastern Duero Drainage (x̄ = 6.9 6-8 n = 99). Also it was lesser the scales number below of lateral line in Northwestern Duero (x̄ = 3.1 3-4 n = 36) than in other populations from Mediterranean drainages (x̄ = 4.6 4-5 n = 63); Western Spain (x̄ = 4.4 4-5 n = 66) and Central-Eastern Duero Drainage (x̄ = 4.2 4-5 n = 99).

Osteology features (Appendix 5)

The smaller snout of Mediterranean populations is more evident in a lateral view of the skull in comparison with other populations (Appendix 5.1) Opercular is in Mediterranean populations higher and narrower than in other populations.

An unexpected result of the osteological analyses was the clear differentiation of the population from Northwestern Duero that presented a narrower skull (Appendix 5.2). The results of the index Head Length/Interorbital Distance shown the Northwestern Duero population with higher values (x̄ = 3,4 n = 16) relative to other populations of Duero (x̄ = 2.99, n = 5), Mediterranean populations (x̄ = 2.7 n = 34) and more similar to the population of Western Spain (x̄ = 3.2 n = 23) (Fig. 4). Mediterranean populations had a skull shorter and wider that other populations studied.

Pharyngeal teeth were different in form and number in Mediterranean populations with respect to other populations. The number of teeth in Mediterranean populations was five teeth on the left side and four on the right side, occasionally 5/5 or 4/4 (RPT x̄ = 4.1; LPT x̄ = 4.9; n = 161). In all the other populations, Western Spain, Central-Eastern Duero and Northwestern Duero the most frequent number was 5/5 occasionally 5/4 or 5/6 (RPT x̄ = 4.9; LPT x̄ = 5.01; n = 183).

The shape of the teeth was also different between populations. In Mediterranean populations teeth were more robust with a conspicuous hook at the end of the crown and with a more reduced masticatory surface. In the rest of populations, teeth were like Pseudochondrostoma and Parachondrostoma thinner than the ones of Mediterranean populations and with knife shape (Appendix 5.3).

The posterior process of the basioccipital bone was thinner in Mediterranean populations (Appendix 5.4)

The coronoid process of the dentary was higher and thinner in population of the Northwestern Duero while the anterior process of the dentary was longer in Mediterranean populations (Appendix 5.5).

Table 1 provides a summary of the differences observed among the species.

Genetics

Phylogenetic analyses based on the MT-CYB gene were congruent with previous studies and supported two main clades in the phylogenetic tree (‍Doadrio et al., 2021). Clade I corresponded to A. occidentale and populations from Northwestern Duero and Clade II to A. oligolepis and the rest of populations (Fig. 5). Within Clade II two sub-clades were well supported, one including populations from Alagón and Cuerpo de Hombre rivers (Tajo Drainage) and Corneja river (Duero Drainage), and a second one grouping populations from Mediterranean drainages clustered together with populations from the Central-Eastern area from Duero Drainage.

Genetic patristic distances based on the MT-CYB (Appendix 6) between Northwestern Duero (mainly Esla sub-basin) and the remaining Achondrostoma analyzed populations ranged from 4.1% (A. occidentale) to 7.9% (A. salmantinum). Populations from Alagón, Cuerpo de Hombre and Corneja rivers showed genetic patristic distances ranging from 2.2-2.8 % (A. oligolepis, populations of the Mediterranean drainages and Central-Eastern Duero drainages) to 0.6-7.7% (A. occidentale and A. salmantinum respectively). The genetic distances estimated in the analyzed populations for the MT-CYB gene fell within the range found for other leuciscins and cyprinid species (‍Madeira et al., 2005; ‍Pérez-Rodríguez et al., 2009; ‍Ghanavi et al., 2016; ‍Jouladeh-Roudbar et al., 2017).

Patristic distances between populations from Central-Eastern Duero with respect to Mediterranean drainages were very low and ranged between 0.4 to 0.7% of divergence (Appendix 6).

When we examined the haplotype network none of the haplotypes were shared between groups: Mediterranean (Ebro and Spanish_Levant); Central-Eastern Duero; Western Spain (Corneja, Duero Drainage, Cuerpo de Hombre, Tajo Drainage and Alagón Tajo Drainage and Northwestern Duero. Central-Eastern Duero population had two different groups of haplotypes, one closer to Mediterranean but other more distant to those populations, with divergence based on uncorrected genetic distance around of 1.5% (Fig. 6).

Several processes such as presence of ancient mitochondrial captures, as consequence of hybridization, or retention of ancestral polymorphism could explain the difficulty of mitochondrial DNA to delimitate two different species clearly recognizable by morphological traits (‍Huber at al., 2008; ‍Perea et al., 2016). Probably, this is the reason of non-correspondence between genetic and morphological differences in Atlantic and Mediterranean populations of the eastern area of Iberian Peninsula. The Mediterranean populations were the most morphologically divergent of all the other populations studied, but presented the smallest genetic distances with respect to the population of the Central-Eastern Duero.

In this study we describe populations corresponding to the populations from the Northwestern Duero, Central-Eastern Duero and Western Spain.

Numerous syntypes of A. arcasii are listed in the Naturistorishche Museum of Wien (NMW) from the Duero and Ebro drainages. But the species was only described with individuals from the Ebro Drainage, in the Ebro River near Logroño (La Rioja) and in the Queiles River in Tudela (Navarra) (‍Steindachner, 1866). Therefore, only individuals from these two localities should be considered as true syntypes. We studied a large series of individuals from the Queiles River near Tudela (see Materials section) and the two syntypes from the same locality (NMW 50646:1.5).

In consequence, A. arcasii should be referred only to the populations from Ebro and Levantine drainages (Mijares, Turia and Palancia drainages). We propose the other three differentiated populations (Central-Eastern Duero, Western Spain and Northwestern Duero) to be considered as three new species.

Description of Achondrostoma populations

The high degree of morphological and genetic differentiation of Achondrostoma populations endemic to Central-Eastern Duero, Western Spain and Northwestern Duero drainages justify the consideration of these population as distinct species. No available names for these populations exist, and therefore these are described as new species in the present study.

Achondrostoma garzonorum sp. nov.

urn:lsid:zoobank.org:act:99188350-392F-4D89-AD8E-E83ECB13E927

Fig. 7, Table 2

Material studied

Holotype: MNCN_ICTIO 293737 69.8 mm SL, 93 mm TL; Alagón River, Tajo Drainage, El Tornadizo, Los Pasiles, Salamanca, Spain, 40°32’34.3”N 5°51’23.1”W, 887 m.a.s.l., Leg. S. Perea, P. Garzón-Heydt, T. Nester and I. Doadrio, 23.III.2019.

Paratypes: MNCN_ICTIO 293736, MNCN_ICTIO 293738 to ICTIO 293761, 25 individuals, Alagón River, Tajo Drainage, El Tornadizo, Los Pasiles, Salamanca, Spain, 40°32’34.3”N 5°51’23.1”W, 887 m.a.s.l., Leg. S. Perea, P. Garzón-Heydt, T. Nester and I. Doadrio, 23.III.2019. MNCN_ICTIO 273977 to ICTIO 273986, MNCN_ICTIO 273987 to ICTIO 274008, 32 individuals, Corneja River, Duero Drainage, San Bartolomé de Corneja, Ávila, Spain, 40°29’22.9”N 5°23’08.7”W, 999 m.a.s.l., Leg. P. Garzón-Heydt and I. Doadrio, 31.V.2009.

Additional material: MNCN_ICTIO 266554 to ICTIO 266564, 12 individuals, Cuerpo de Hombre River, Tajo Drainage, Montemayor del Río, Salamanca, Spain, 40°20’45.8”N 5°52’30.4”W, 637 m.a.s.l. Leg. P. Garzón-Heydt, J.L. González and I. Doadrio, 21.III.2009. MNCN_ICTIO 283373 to ICTIO 283381, 9 individuals, Cuerpo de Hombre River, Tajo, Drainage, Montemayor del Río, Salamanca, Spain, 40°20’46.7”N 5°53’48.8”W, 637 m.a.s.l., Leg. P. Garzón-Heydt, J.L. González and I. Doadrio, 5.V.2010. MNCN_ICTIO 210005 to ICTIO 210010, 6 individuals, Corneja River, Duero Drainage, Villafranca de la Sierra, Ávila, Spain, 40°30’01.5”N 5°14’01.4”W, 1111 m.a.s.l., Leg. I. Doadrio, 9.IX.1999.

Diagnosis

Achondrostoma garzonorum sp. nov. is a member of the Achondrostoma genus (‍Robalo et al., 2007). Achondrostoma garzonorum sp. nov. can be differentiated from all other known species of Achondrostoma according to the following set of characters: 43-‍49 (x̄ = 45.9; M_d = 46; n = 66) canaliculate scales on the lateral line; 6-‍7 (x̄ = 6.8; M_d = 7; n = 66) scales above the lateral line; 4-‍5 (x̄ = 4.4; M_d = 4; n = 66) scales below the lateral line; 5/5 pharyngeal teeth. Low body depth (SL/BD > 4.4; BD/BLD < 2.2). Dentary with coronoid process high and narrow. Genetic distances from the other species of Achondrostoma inferred from the mitochondrial cytochrome b gene sequence were: about 7.7% with respect to A. salmantinum; about 6.1% with respect to A. occidentale; about 2.2% with respect to A. oligolepis, 2.7-2.8% with A. arcasii (here defined as the Ebro and Mijares, Turia and Palancia drainages); 2.4% with Central-Eastern Duero and 6.1% with Northwestern Duero. The new species has 3 autapomorphies, none of them transversions, in the cytochrome b gene (Table 3).

Description

D III (II) = 7, A III = 7, P I 12, V I 8, SLL = 45.9 (43-‍49), SRA = 6.8 (6-‍7), SRB = 5 (5-‍5.6), DPL 5 DPT 5, Vr = 37.4 (36-‍38). Morphometric and meristic characters of the type material are given in Table 2; measurements used in the morphometric study appear in Appendix 7. A medium-sized species that rarely reaches 150 mm total length. The head is large with the mouth subterminal and SL/HL is 3.8-4.5 (x̄ = 4.2). The maximum body is low and the head length is larger than maximum body depth and BD/HL is 0.7-1 (x̄ = 0.9). The preorbital distance is short about 0.7-1.2 (x̄ = 1) times the eye diameter. Most individuals have a conspicuous depression between the posterior part of the head and start of the trunk. The ventral fins are inserted approximately at the same level of the origin of the dorsal fin. Predorsal length is 0.9-1.2 (x̄ = 1 times preventral length. The caudal peduncle is low and minimum body depth is 3.2-5 (x̄ = 3.7) times the length of the caudal peduncle and 2.2-3.4 (x̄ = 1.8) times the length of the anal peduncle. The minimum body depth is about two times the body depth. Caudal fin is short, and the head length is 1-‍1.5 (x̄ = 1.2) times the length of the caudal fin.

Pigmentation pattern

The upper part of the body is dark grey or dark brown; the ventral side is silvery. Ventral, anal and pectoral fin insertion points are red. Fins rays are black. The scales of the lateral line are black pigmented. The head is clearly lighter below the level of the eye (Fig. 8). The peritoneum is black.

Etymology

The species name garzonorum is derived from the Garzón-Heydt family, especially: Dra Paloma Garzón-Heydt, Jesús Garzón-Heydt, and Dra Guillermina Garzón-Heydt for their contribution to the study and conservation of rivers and fauna of the region where A. garzonorum inhabits.

Distribution

This new species is endemic to three rivers of the Iberian Peninsula the Alagón and Cuerpo de Hombre rivers in Tajo Drainage and the Corneja River in the Duero Drainage. In Alagón river the species is only present in the head water near of its source. In Cuerpo de Hombre river the range of the species is localized near of its confluence into the Alagón River. In Corneja river the species inhabit a small stretch of the river before its confluence with the Tormes river (Fig. 9).

Common names

Bermeja, Bermejuela salmantina.

Remarks

The species A. garzonorum hybridized with Pseudochondrostoma polylepis (Steindachner,1864) in Cuerpo de Hombre River and for this reason the individuals of Cuerpo de Hombre were discarded of type series. Not data on the reproduction of the species exist. The species is a typical habitant of rivers with clear water and from moderate to high water flow, in areas with granitic rocks in the riverbed. The species should be considered Critically Endangered according to the IUCN red list criteria due to the extent of its occurrence is lesser than 100 km² and its populations are severely fragmented. Only three small populations exist and probably due to human alterations (pollution and dams) the population from the Cuerpo de Hombre river is endangered as a consequence of genetic introgresion with Pseudochondrostoma polylepis. Hybridization between species of the genus Pseudochondrostoma and Achondrostoma has been previously reported when species of these two genera inhabit the same drainage (‍Collares-Pereira & Coelho, 1983; ‍Elvira, 1986; ‍Doadrio et al., 2011; ‍Vieira-Lanero et al., 2019). However, in Corneja river hybrids with Pseudochondrostoma duriense, whichinhabit together with A. garzonorum, were not detected. No other fish species were collected in the stretch of the Alagón river where this species inhabits.

Achondrostoma numantinum sp. nov.

urn:lsid:zoobank.org:act:8616548B-FE9F-469B-81DA-6C18B46AA2DF

Fig. 10, Table 4

Material studied

Holotype: MNCN_ICTIO 293768, SL 77.1 mm, TL 89.4 mm, Voltoya River, Duero Drainage, Labajos, Ávila, Spain, 40°50’54.4”N 4°34’20.3”W, 1.064 m.a.s.l., Leg., P. Garzón-Heydt, S. Perea, T. Nester, and I. Doadrio, 24.III.2019.

Paratypes: MNCN_ICTIO 293767, MNCN_ICTIO 293769 to ICTIO 293772, 5 individuals, Voltoya River, Duero Drainage, Labajos, Ávila, Spain, 40°50’54.4”N 4°34’20.3”W, 1.064 m.a.s.l., Leg. P. Garzón-Heydt, S. Perea, T. Nester and I. Doadrio, 24.III.2019. MNCN_ICTIO 293762 to ICTIO 293766, 5 individuals, Adaja River, Duero Drainage, Blascosancho, Ávila, Spain, 40°52’05.1”N 4°41’00.5”W, 890 m.a.s.l., Leg. P. Garzón-Heydt, S. Perea, T. Nester and I. Doadrio, 24.III.2019. MNCN_ICTIO 273156 to ICTIO 273161, MNCN_ICTIO 273156 to ICTIO 273161, 6 individuals, Adaja River, Duero Drainage, Blascosancho, Ávila, Spain, 40°52’05.1”N 4°41’00.5”W, 904 m.a.s.l., Leg. P. Garzón-Heydt, J.L. González and I. Doadrio, 12.VII.2009. MNCN_ICTIO 296779 to ICTIO 296792, 14 individuals Cega River, Duero Drainage, Lastras de Cuellar, Segovia, Spain, 41°16’27.3”N 4°05’32.9”W, 900 m.a.s.l., Leg. P. Garzón-Heydt, J.L. González and I. Doadrio, 24.VII.2010.

Additional material: MNCNUZA_ICTIO 589 to ICTIO 608, 20 individuals, Pedro River, Duero Drainage, Cuevas de Ayllón, Soria, Spain, 41°23’23.0”N 3°18’29.4”W, Leg. E. Martínez, B. Gutiérrez, and L. Ambrosio, 2.VI.2010. MNCN_ICTIO 30197 to ICTIO 30208, 12 individuals, Adaja River, Duero Drainage, Pradosegar, Ávila, Spain, 40°33’33.6”N 5°03’51.8”W, Leg. I. Doadrio, 18.V.1981. MNCN_ICTIO 33626 to ICTIO 33649, 24 individuals, Adaja River, Duero Drainage, Blascosancho, Burgos, Spain, 40°52’25.7”N 4°40’50.0”W, Leg. I. Doadrio, 18.V1981. MNCN_ICTIO 33853 to ICTIO 336888, 36 individuals, Ucero River, Duero Drainage, Ucero, Soria, Spain, 41°42’47.4”N 3°03’04.1”W, Leg. I. Doadrio, 30.XI.1983. MNCN_ICTIO 45175 to ICTIO 45214, 40 individuals, Moros River, Duero Drainage, Anaya, Segovia, Spain, 40°59’35.6”N 4°18’43.8”W, Leg. P. Rincón, 7.V.1986. MNCN_ICTIO 103403 to ICTIO 103419, 17 individuals, Camesa River, Duero Drainage, Santa Olalla, Cantabria, Spain, 42°55’54.0”N 4°12’15.0”W, Leg. I. Doadrio, A. Perdices, J.A. G. Carmona, 19.VIII.1991. MNCN_ICTIO 109186 to ICTIO 109219, 34 individuals, Cega River, Duero Drainage, Pajares de Pedraza, Segovia, Spain, 41°09’48.9”N 3°51’03.6”W, Leg. A. Perdices, J. Cubo and J. Dominguez, 13.X.1994. MNCN_ICTIO 109233 to ICTIO 109278, 46 individuals, Duratón River, Duero Drainage, Duruelo, Segovia, Spain, 41°14’18.6”N 3°38’30.8”W, Leg. I. Doadrio, 13.X.1994. MNCN_ICTIO 117473 to ICTIO 117483, 11 individuals, Zapardiel River, DueroDrainage, Los Crespos, Ávila, Spain, 40°52’50.0”N 4°59’26.1”W, Leg. B. Gutiérrez, E. Martínez and L. Ambrosio, 13.VI.1995. MNCN_ICTIO 117542 to ICTIO 117555, 14 individuals, Voltoya River, Duero Drainage, Urraca Miguel, Ávila, Spain, 40°41’20.0”N 4°31’08.1”W, Leg. B. Gutiérrez, E. Martínez and L. Ambrosio, 15.VI.1995. MNCN_ICTIO 117462 to ICTIO 117465, 4 individuals, Voltoya River, Duero Drainage, El Espinar, Segovia, Spain, 40°41’43.2”N 4°21’01.6”W, Leg. B. Gutiérrez, E. Martínez and L. Ambrosio, 4.VII.1995. MNCN_ICTIO 117639 to ICTIO 117642, 4 individuals, Pirón River, Duero Drainage, Samboal, Segovia, Spain, 41°15’19.8”N 4°26’08.3”W, Leg. B. Gutiérrez, E. Martínez and L. Ambrosio, 28.VI.1995. MNCN_ICTIO 117666 to ICTIO 117668, 3 individuals, Revinuesa River, Duero Drainage, Vinuesa, Segovia, Spain, 41°55’54.2”N 2°46’11.4”W, Leg. L. Ambrosio, 11.VII.1995. MNCN_ICTIO 117691 to ICTIO 117710, 20 individuals, Moros River, Duero Drainage, Vegas de Matute, Segovia, Spain, 40°47’49.0”N 4°15’27.0”W, Leg. B. Gutiérrez, E. Martínez and L. Ambrosio, 4.VII.1995. MNCN_ICTIO 117828 to ICTIO 117847, 20 individuals, Tielmes River, Duero Drainage, Fresno de Caracena, Soria, Spain, 41°27’09.4”N 3°05’19.1”W, Leg. B. Gutiérrez, E. Martínez and L. Ambrosio, 6.VII.1995. MNCN_ICTIO 117848 to ICTIO 117867, 20 individuals, Aranzuelo River, Duero Drainage, Arauzo de Torre, Burgos, Spain, 41°48’03.6”N 3°25’18.8”W, Leg. B. Gutiérrez, E. Martínez and L. Ambrosio, 12.VII.1995. MNCN_ICTIO 117921to ICTIO 117940, 20 individuals, Pilde River, Duero Drainage, Brazacorta, Burgos, Spain, 41°42’48.2”N 3°22’04.4”W, Leg. B. Gutiérrez, E. Martínez and L. Ambrosio, 13.VII.1995. MNCN_ICTIO 128732 to ICTIO 128735, 4 individuals, Eresma River, Duero Drainage, Olmedo, Valladolid, Spain, 41°19’31.3”N 4°37’11.6”W, Leg. B. Gutiérrez, E. Martínez and L. Ambrosio, 15.VII.1995. MNCN_ICTIO 128891 to ICTIO 128902, 12 individuals, Cega River, Duero Drainage, Viana de Cega, Valladolid, Spain, 41°32’13.3”N 4°45’46.8”W, Leg. B. Gutiérrez, E. Martínez and L. Ambrosio, 27.VI.1995. MNCN_ICTIO 129140 to ICTIO 129182, 43 individuals, Caracena River, Duero Drainage, Caracena, Soria, Spain, 41°23’08.6”N 3°05’16.8”W, Leg. B. Gutiérrez, E. Martínez and L. Ambrosio, 6.VII.1995. MNCN_ICTIO 130068 to ICTIO 130084, 17 individuals, Arandilla River, Duero Drainage, Huerta del Rey, Burgos, Spain, 41°50’53.5”N 3°20’32.6”W, Leg. B. Gutiérrez, E. Martínez and L. Ambrosio, 13.VII.1995. MNCN_ICTIO 130476 to ICTIO 130488, 13 individuals, Urbell River, Duero Drainage, Santa Cruz del Tozo, Burgos, Spain, 42°38’41.0”N 3°53’07.0”W, Leg. B. Gutiérrez, E. Martínez and L. Ambrosio, 22.VII.1995. MNCN_ICTIO 161465 to ICTIO 161513, 49 individuals, Rubagón River, Duero Drainage, Porquera de Santullán, Palencia, Spain, 42°53’24.0”N 4°17’26.1”W, Leg. I. Doadrio, 16.VIII.1995. MNCN_ICTIO 161831 to ICTIO 131865, 35 individuals, Boedo River, Duero Drainage, Báscones de Ojeda, Palencia, Spain, 42°40’03.9”N 4°31’27.6”W,Leg. I. Doadrio, 17.VIII.1995. MNCN_ICTIO 169154 to ICTIO 169156, 3 individuals, Arlanza River, Duero Drainage, Palacios de la Sierra, Burgos, Spain, 41°58’45.9”N 3°09’40.1”W, Leg. I. Doadrio, 20.VII.1995. MNCN_ICTIO 192329 to ICTIO 192331, 3 individuals, Duero River, Duero Drainage, Garray, Soria, Spain, 41°48’36.3”N 2°26’53.0”W, Leg. I. Doadrio and B. Elvira, 31.VII.1981. MNCN_ICTIO 192395 to ICTIO 192399, 5 individuals, Nava River, Duero Drainage, Fuentelcésped, Burgos, Spain, 41°36’07.7”N 3°37’56.8”W, Leg. B. Elvira, 25.VI.1978. MNCN_ICTIO 193004 to ICTIO 193036, 33 individuals, Cubillo River, Duero Drainage, Madrigalejo del Monte, Burgos, Spain, 42°06’55.6”N 3°45’06.8”W, Leg. B. Elvira, 29.IX.1982. MNCN_ICTIO 210419 to ICTIO 210428, 10 individuals, Talegones River, Duero Drainage, Berlanga de Duero, Soria, Spain, 41°27’09.8”N 2°52’38.3”W, Leg. I. Doadrio, 22.X.1999. MNCN_ICTIO 210522 to ICTIO 210524, 3 individuals, Merdancho River, Duero Drainage, Renieblas, Soria, Spain, 41°49’10.0”N 2°23’02.9”W, Leg. I. Doadrio, 29.X.1999. MNCN_ICTIO 210547, ICTIO 210548, 2 individuals, Hornija River, Duero Drainage, Peñaflor de Hornija, Valladolid, Spain, 41°43’07.7”N 4°59’03.7”W, Leg. I. Doadrio, 23.XI.1999. MNCN_ICTIO 211821 to ICTIO 211836, 16 individuals, Ausín River, Duero Drainage, Revillarruz, Burgos, Spain, 42°13’47.3”N 3°39’29.9”W, Leg. I. Doadrio, 6.XI.1999. MNCN_ICTIO 212552 to ICTIO 212587, 36 individuals, Morón River, Duero Drainage, Morón de Almazán, Soria,Spain, 41°24’54.7”N 2°24’30.1”W, Leg. I. Doadrio, 22.X.1999. MNCN_ICTIO 212910 to ICTIO 212931, 22 individuals, Cubillo River, Duero Drainage, Zael, Burgos, Spain, 42°06’26.3”N 3°49’32.8”W, Leg. I.Doadrio, 6.XI.1999. MNCN_ICTIO 213826 to ICTIO 213880, 55 individuals, Hormazuela River, Duero Drainage, Estépar, Burgos, Spain, 42°16’51.3”N 3°54’50.1”W, Leg. I. Doadrio, 7.XI.1999. MNCN_ICTIO 213911 to ICTIO 213942, 32 individuals, Escalote River, Duero Drainage, Berlanga de Duero, Soria, Spain, 41°28’30.6”N 2°51’00.9”W, Leg. I. Doadrio, 22.X.1999. MNCN_ICTIO 192184, 1 individual, Tera River, Duero Drainage, Espejo de Tera, Soria, Spain, 41°53’01.3”N 2°29’24.4”W, Leg. I. Doadrio, 12.II.1974. MNCN_ICTIO 194276, ICTIO 194277, 2 individuals, Duero River, Duero Drainage, Castronuño, Valladolid, Spain, 41°23’31.1”N 5°15’45.6”W, Leg. B. Elvira and I. Doadrio, 13.VII.1981. MNCN_ICTIO 194307 to ICTIO 194322, 16 individuals, Arlanza River, Duero Drainage, Lerma, Burgos, Spain, 42°01’50.5”N 3°45’34.7”W, Leg. B. Elvira and I. Doadrio, 17.VIII.1979. MNCN_ICTIO 210521, 1 individual, Fuentepinilla River, Duero Drainage, Fuentepinilla, Soria, Spain, 41°34’09.4”N 2°45’46.1”W, Leg. F. Morcillo and I. Doadrio, 25.X.1999. MNCN_ICTIO 215228 to ICTIO 215243, 16 individuals, Izana River, Duero Drainage, Quintana Redonda, Soria, Spain, 41°38’35.1”N 2°36’36.0”W, Leg. F. Morcillo and I. Doadrio, 25.X.1999. MNCN_ICTIO 215244 to ICTIO 215282, 39 individuals, Araviana River, Duero Drainage, Ólvega,Soria, Spain, 41°44’10.4”N 1°56’43.8”W, Leg. F. Morcillo and I. Doadrio, 25.X.1999. MNCN_ICTIO 192975 to ICTIO 192990 16 individuals, Duratón River, Duero Drainage, Sebúlcor, Segovia, Spain, 41°17’51.5”N 3°52’05.2”W, Leg. B. Elvira and I. Doadrio, 27.VII.1981. MNCN_ICTIO 29680 to ICTIO 296811, 10 individuals, Oroncillo River, Duero Drainage, Pancorbo, Burgos, Spain, 42°37’40.3”N 3°07’06.4”W, Leg. I. Doadrio, 27.VII.1981. MNCN_ICTIO 30122 to ICTIO 30165 and MNCN_ICTIO 245421 to ICTIO 245447, 71 individuals, Almar River, Duero Drainage, Peñaranda de Bracamonte, Salamanca, Spain, 40°52’20.1”N 5°13’34.6”W, Leg. B. Elvira and I. Doadrio, 13.VIII.1981. MNCN_ICTIO 217598 to ICTIO 217609 12 individuals, Valdeginate River, Duero Drainage, Cisneros, Palencia, Spain, 42°12’50.1”N 4°50’46.1”W, Leg. I. Doadrio, 25.XI.1999. MNCN_ICTIO 217610 to ICTIO 217616, 7 individuals, Maderano River, Duero Drainage, Castrillo de Onielo, Palencia, Spain, 41°51’21.1”N 4°19’43.5”W, Leg. I. Doadrio, 26.XI.1999. MNCN_ICTIO 137076 to ICTIO 137077, 2 individuals, Villalobón River, Duero Drainage, Villalobón, Palencia, Spain, 42°01’45.7”N 4°30’05.2”W, Leg. IFIE, 25.IV.1945. MNCN_ICTIO 193591 to ICTIO 193607, 17 individuals, Rivera River, Duero Drainage, Ventanilla, Palencia, Spain, 42°52’51.3”N 4°33’54.6”W, Leg. Brañosera, 1.VIII.1981. MNCN_ICTIO 140636 to ICTIO 140641 6 individuals, Carrión River, Duero Drainage, Carrión de los Condes, Palencia, Spain, 42°20’28.5”N 4°36’33.9”W, Leg. IFIE, 15.XI.1952.MNCN_ICTIO 296793 to ICTIO 2968019, Voltoya River, Duero Drainage, Juarros de Voltoya, Segovia, Spain, 41°02’11.1”N 4°31’14.1”W, 840 m.a.s.l., Leg. P. Garzón-Heydt, J. L. González and I. Doadrio, 24.VII.2010.

Diagnosis

Achondrostoma numantinum sp. nov. is a member of the Achondrostoma genus (‍Robalo et al., 2007). Achondrostoma numantinum sp. nov. can be differentiated from all other known species of its genus according to the following set of characters: 43-‍48 (x̄ = 45, 1, M_d = 45 n = 99) canaliculated scales on the lateral line; 6-‍8 (x̄ = 6.9, M_d = 7 n = 99) scales above the lateral line; 4-‍5 (x̄ = 4.3, M_d = 4 n = 99) scales below the lateral line; small head (SL/HL> 4.2). High body depth in comparison to caudal peduncle depth (BD/BLD > 2). (6)5/5(6) pharyngeal teeth. Dentary with short anterior process and coronoid process high. Genetic distances from the other species of Achondrostoma inferred from the mitochondrial cytochrome b gene sequence were: about 7.7 % with respect to A. salmantinum, about 6.5 % with respect to A. occidentale, about 2.2-2.3 % with respect to A. oligolepis, 0.6-0.7 % with A. arcasii (here defined as the Ebro and Mijares, Palancia and Turia drainages), and 6.6 % with Northwestern Duero. The new species has one autapomorphy (non-transversion) in the mitochondrial cytochrome b gene (Table 3).

Description

D III = 7, A III = 7, P I 12-‍13, V I 7-‍8, SLL = 45.1 (43-‍48), SRA = 6.9 (6-‍7), SRB = 5 (4-‍5), DPL 5 (6) DPT 5 (6), Vr = 37.9 (37-‍38). Morphometric and meristic characters of the type material are given in Table 4. Measurements used in the morphometric study appear in Appendix 8. A medium sized species that rarely reaches 150 mm standard length. The head is small with the mouth subterminal SL/HL is 4.2-5.6 (x̄ = 4.6). Head length is 1-‍1.4 (x̄ = 1.1) times maximum body depth. Head length is similar to posterior head height (HL/HH ratio 1-‍1.3 x̄ = 1.1). The preorbital distance is similar to the eye diameter, measuring 0.7-1.4 (x̄ = 1) times the eye diameter at most. The ventral fins are inserted in the origin of the dorsal fin. Predorsal length is 0.9 -1.1 (x̄ = 1) times preventral length. Minimum body depth is 3.1-4.2 (x̄ = 3.6) times the length of the caudal peduncle and 1.7-2.6 (x̄ = 2.1) times the length of the anal peduncle. The caudal fin is short, the same length as the head.

Pigmentation pattern

The general colour pattern in A. numantinum sp. nov. is similar to those of A. garzonorum sp. nov. and A. arcasii. The upper part of the body is dark grey or dark brown; the ventral side being silvery or gold. Ventral, anal and pectoral fin insertion points are red, increasing in intensity and extension in the spawning period. The scales of the lateral line are black pigmented (Fig. 8).

Etymology

The species name numantinum is derived from the name given to the pre-Roman population inhabiting an ancient Celtiberian settlement around of the current Garray village in Soria (Central Spain). This population was known for his courage and after 13 months of siege for the romans, the Numantians decided to burn the city before surrendering.

Distribution

The species is endemic to the Duero Drainage but absent in the Northwestern region of this drainage (Esla sub-basin and Portugal rivers in the Duero Drainage) (Fig. 9).

Common name

Bermejuela numantina.

Remarks

Achondrostoma numantinum lives in rivers and streams placed in the central plateau from Spain with heights over 800 m.a.s.l. in oligotrophic waters shady with vegetation. Breeding occurs from April to the end of August (‍Rincón & Lobón-Cerviá, 1989). The main diet components are detritus, plants and invertebrates (‍Lobón-Cerviá & Rincón, 1994). The large number of dams and reservoirs for hydroelectric and agricultural use, in Duero Drainage, the introduction of invasive freshwater fish species, and pollution are the main threats to the conservation of A. numantinum. However, it is still a common species throughout the Duero Drainage. The trend of its populations is unknown, and projections and models in climate change scenarios have not been made on this species. All this information is necessary to include to A. numantinum in the future in any category of threatened of IUCN, so far it is a data deficient species (DD).

Achondrostoma asturicense sp. nov.

urn:lsid:zoobank.org:act:D2A37AB1-816F-42C9-A6B5-EAD4A4F4FF1B

Fig. 11, Table 5

Material studied

Holotype: MNCN_ICTIO 296812, SL 66.8 mm, 80.3 TL mm, Truchas River, Duero Drainage, Sotillo de Sanabria, Zamora, Spain, 42°05’12.0”N 6°42’48.5”W, 1.600 m.a.s.l., Leg., J. Garzón-Heydt, 31.VIII.1974.

Paratypes: MNCN_ICTIO 296813, 1 individual, Truchas River, Duero Drainage, Sotillo de Sanabria, Zamora, Spain, 42°05’12.0”N 6°42’48.5”W, 1.600 m.a.s.l., Leg., J. Garzón-Heydt, 31.VIII.1974. MNCN_ICTIO 192192-‍192197, 6 individuals, Peces Lagoon, Duero Drainage, Galende, Zamora, Spain, 42°10’34.0”N 6°43’46.2”W, 1700 m.a.s.l., Leg. J. Garzón-Heydt, 15.V.1974. MNCN_ICTIO 296.814-296.821, 8 individuals, Peces Lagoon, Duero Drainage, Galende, Zamora, Spain, 42°10’34.0”N 6°43’46.2”W, 1700 m.a.s.l., Leg. J. Garzón-Heydt, 17.V.1974. MNCN_ICTIO 192324-‍192328, 5 individuals, Garandones Lagoon, Duero Drainage, Galende, Zamora, Spain, 42°08’17.9”N 6°47’11.8”W, 1614 m.a.s.l., Leg. J. Garzón-Heydt, 18.V.1974. MNCN_ICTIO 257371-‍257383, MNCN_ICTIO 257385-‍86, 15 individuals, Tera River, Duero Drainage, Ribadelago, Zamora, Spain, 42°07’22.1”N 6°44’53.3”W, 1007 m.a.s.l., P. Garzón-Heydt and I. Doadrio, 5.VI.2003.

Additional material: MNCN_ICTIO 30518, 1 individual, Luna River, Duero Drainage, Villasecino, León, Spain, 42°57’04.0”N 6°01’32.7”W, Leg. J. Muñoz Cobos, 8.VII.1975. MNCN_ICTIO 163649, 1 individual, Torío River, Duero Drainage, Garrafe de Torío, León, Spain, 42°43’54.2”N 5°31’12.3”W, Leg. I. Doadrio, 15.VIII.1995. MNCN_ICTIO 192482-‍192493, 12 individuals Cea River, Duero Drainage, Sahagún, León, Spain, 42°22’36.5”N 5°02’26.0”W, Leg. B. Elvira, 20.VIII.1978. MNCN_ICTIO 193458-‍193479, 22 individuals Órbigo River, Duero Drainage, Azadón, León, Spain, 42°38’13.2”N 5°49’06.7”W, Leg. I. Doadrio, 27.IX.1982. MNCN_ICTIO 296822-‍296852, 31 individuals Cea River, Duero Drainage, Mondreganes, León, Spain, 42°41’47.9”N 5°01’38.1”W, Leg. P. Garzón-Heydt and I. Doadrio, 15.VII.2009. MNCN_ICTIO 296.853-296.854, 2 individuals Esla River, Duero Drainage, Villarroañe, León, Spain, 42°41’47.9”N 5°01’38.1”W, Leg. P. Garzón-Heydt and I. Doadrio, 4.VI.2010. MNCN_ICTIO 296.855-296.857, 3 individuals Porma River, Duero Drainage, Puente de Villarente, León, Spain, 42°33’07.1”N 5°26’39.5”W, Leg. P. Garzón-Heydt and I. Doadrio, 4.VI.2010. MNCN_ICTIO 296.858-296.869, 12 individuals Cea River, Duero Drainage, Puente Almuhey, León, Spain, 42°33’07.1”N 5°26’39.5”W, Leg. P. Garzón-Heydt and I. Doadrio, 4.VI.2010. MNCN_ICTIO 296.870-296.879, 10 individuals Curueño River, Duero Drainage, Ambasaguas de Curueño, León, Spain, 42°42’32.0”N 5°22’39.8”W, Leg. P. Garzón-Heydt and I. Doadrio,4.VI.2010. MNCN_ICTIO 296.880-296.903, 24 individuals Omaña River, Duero Drainage, Las Omañas, León, Spain, 42°40’42.4”N 5°52’16.8”W, Leg. P. Garzón-Heydt and I. Doadrio, 30.VI.2010. MNCNAT_ICTIO 2882-‍2891, 10 individuals Torío River, Duero Drainage, Villarrodrigo de las Regueras, León, Spain, 42°37’49.8”N 5°31’31.2”W, Leg. P. Garzón-Heydt and I. Doadrio, 9.VI.2005. MNCNAT_ICTIO 2924-‍2963, 70 individuals Torío River, Duero Drainage, Villaobispo de las Regueras, León, Spain, 42°36’37.6”N 5°32’22.2”W, Leg. S. Perea and I. Doadrio, 9.VI.2005. MNCNAT_ICTIO 3994-‍4003, 10 individuals Porma River, Duero Drainage, Camposolillo, León, Spain, 42°58’51.8”N 5°15’23.3”W, Leg. I. Doadrio, 6.X.2006. MNCNAT_ICTIO 4004-‍4033 25 individuals Torío River, Duero Drainage, Palazuelo de Torío, León, Spain, 42°42’11.9”N 5°31’48.0”W, Leg. S. Perea and I. Doadrio, 29.IX.2006.

Diagnosis

Achondrostoma asturicense sp. nov. is a member of the Achondrostoma genus (‍Robalo et al., 2007). Achondrostoma asturicense sp. nov. can be differentiated from all other known species of its genus according to the following set of characters: 38-‍44 (x̄ = 40.9, M_d = 41 n = 36) canaliculate scales on the lateral line; 5-‍6 (x̄ = 5.8, M_d = 6 n = 36) scales above the lateral line; 3-‍4 (x̄ = 3.1, M_d = 3 n = 36) scales below the lateral line. Caudal peduncle low (SL/BLD<10). High body depth in comparison to caudal peduncle depth (BD/BLD > 2). 5/5 pharyngeal teeth. Dentary with coronoid process wide. Narrow skull with HL/ID>3. Genetic distances from the other species of Achondrostoma inferred from the MT-CYTB gene sequence were: about 7.7 % with respect to A. salmantinum, about 4.1 % with respect to A. occidentale, about 6-‍6.3 % with respect to A. oligolepis, 6.8-6.9 % with A. arcasii (here defined as the Ebro and adjacent Mediterranean rivers), and 6.6 % with Central-Eastern Duero. The new species has 13 autapomorphies in the mitochondrial cytochrome b gene, one of which is a transversion (Table 3).

Description

D III (II) = 7, A III = 7, P I 13, V I 7-‍8, SLL = 40.9 (38-‍44), SRA = 5.8 (5-‍6), SRB = 3.1 (3-‍4), DPL 5 DPT 5, Vr = 37.9 (37-‍38). Morphometric and meristic characters of the type material are given in Table 5. Measurements used in the morphometric study appear in Appendix 9. A medium sized species that rarely reaches 120 mm standard length. The head is large as in A. garzonorum with the mouth subterminal SL/HL is 3.7-4.5 (x̄ = 4.2). Head length is similar to maximum body depth (x̄ = 1, 0.8-1.2). Head height is lesser that the head length (HL/HH ratio 1-‍1.3 x̄ = 1.2). The preorbital distance is lesser to the eye diameter, measuring 0.7-1.1 (x̄ = 0.9) times the eye diameter. The ventral fins are inserted in the origin of the dorsal fin, the proportion (ratio PrD/PrV 1 -1.1; x̄ = 1). The caudal peduncle is large and low minimum body depth is 3.4-4.2 (x̄ = 3.7) times the length of the caudal peduncle and 2-‍2.5 (x̄ = 2.2) times the length of the anal peduncle. The caudal fin is short, the same length as the head.

Pigmentation pattern

The general colour pattern in A. asturicense sp. nov. is similar to those of A. garzonorum sp. nov. and A. arcasii. The upper part of the body is dark grey or dark brown; the ventral side being silvery or gold. Ventral, anal and pectoral fin insertion points are red, increasing in intensity and extension in the spawning period. The scales of the lateral line are black pigmented (Fig.8).

Etymology

The species name asturicense is derived from the name Astura given to the Esla river during the Roman empire.

Distribution

The species is endemic to the Esla sub-basin within of the Duero Drainage and it is probably present also in Duero Drainage in Portugal. (Fig. 9).

Common name

Bermejuela del Esla.

Remarks

Achondrostoma asturicense lives in rivers and lakes placed in the western of the Cantabrian mountains in oligotrophic waters shady with vegetation. Breeding occurs during summer and spring. As occurs in A. numantinum the large number of dams and reservoirs for hydroelectric and agricultural use, in Duero Drainage, the introduction of invasive freshwater fish species, and pollution are the main threats to the conservation of the species. Achondrostoma asturicense is still a common species but with more restricted area of distribution than A. numantinum. The trend of their populations is unknown, and projections and models in climate change scenarios have not been made on this species. Identical to A. numantinum, this information is necessary to include this species in the future in any category of threatened of IUCN, so far it is a data deficient species (DD).

The distribution of Achondrostoma species, including the new species described in this work, is shown in Fig. 12. The populations from Galicia and Tajo-Júcar were named A. asturicense? and A. numantinum? attending to the genetically closest populations (‍Robalo et al., 2006) but they may be different species and a morphological study must be carried out.

Acknowledgments[Up]

Many persons have participated in the field sampling trips. We warmly thank J. L. González, P. Garzón-Heydt, I. Doadrio Jr., A. Doadrio. We would also like to thank L. Alcaraz, for laboratory work, G. Solís, curator of ichthyological collection, and I. Rey and B. Álvarez, curators of the DNA collection of the National Museum of the Natural Sciences (MNCN-CSIC). We also thank C. Parejo and M. Pérez for her technical assistance in non-destructive techniques with the computerized tomography scan at the MNCN-CSIC. This research study was funded by the Spanish Ministry of Science and Innovation and the State Agency of Investigation (MCIN/ AEI/ 10.13039/501100011033) as a part of the Project Aphanius (PID2019-103936GB-C22).