Morphology of two native catfishes from the Sierra Madre Occidental, México: I. pricei and Ictalurus sp. (Siluriformes: Ictaluridae)

Abstract

Introduction: Morphotypes of native catfish of the genus Ictalurus (Siluriformes: Ictaluridae) are known to occur in allopatry in the northern Sierra Madre Occidental of Mexico, with only the Yaqui catfish (Ictalurus pricei) taxonomically described. Recent genetic analysis of these morphotypes has revealed the monophyly of the I. pricei complex, which indicates Ictalurus sp. from the Culiacán River and San Lorenzo River basins as its nearest genetic relative and recognizes as an evolutionarily significant unit the Culiacán River and San Lorenzo River morphotypes. Objective: To compare the meristic and morphometric characteristics of the catfish of the Culiacán River basin with its nearest genetic relative, the Yaqui catfish, in order to determine the presence of distinctive morphological characters that support genetic evidence previously reported for these morphotypes. Methods: Catfish specimens were collected during various field expeditions (1990-2012) to remote sites of the Sierra Madre Occidental and conducted in the Yaqui River and Culiacán River basins with the purpose of morphological comparison. Forty-five morphological characters (40 morphometric and five meristic) were examined in 76 adult specimens – 52 Ictalurus sp. and 24 Ictalurus pricei. Three groups were subject to a discriminant function analysis (DFA), including two Ictalurus sp. groups from the Humaya River and Tamazula River sub-basins, representing the Culiacán River basin, and one I. pricei group representing the Yaqui River basin. The standardized measurements and meristic data of the catfish morphotypes were compared by means of DFA. Results: The DFA revealed 12 characters to be significantly different (P < 0.01) among the groups compared. The morphological characters separating the Ictalurus sp. (Culiacán River basin) from the Yaqui catfish were associated with lower anal, pelvic and pectoral fin ray numbers, shorter head and predorsal lengths, shorter longest lateral barbel and longest dorsal ray lengths and a narrower premaxilar dentary plate; and finally longer distances in Ictalurus sp. for dorsal-fin origin to last anal-fin ray base and dorsal-fin origin to posterior end of the adipose fin base. The standardized coefficients for canonical variables 1 and 2 accounted for 85.6 % and 14.4 % of the total variation, respectively. Conclusions: The distinctive morphological characters of the Ictalurus sp. found in the Culiacán River basin, combined with the known mitochondrial evidence for this morphotype, identify it as an evolutionarily significant unit that requires description as a new species based on taxonomical protocols.

Multi-locus phylogeny of the catfish genus Ictalurus Rafinesque, 1820 (Actinopterygii, Siluriformes) and its systematic and evolutionary implications

“…Another differentiated group was represented by the specimens of Ictalurus sp. from the Culiacan/San Lorenzo rivers, confirming previous morphological findings that indicated this population as a potential undescribed taxon [ 20 ]. Similarly, the specimens of Ictalurus sp.…”

“…Such is the case of Ictalurus lupus ( 2 , 18 – 19 ), which occurs along the extensive Bravo River basin and other independent drainages along the Gulf of Mexico slope, such as the Cuatro Cienegas valley and Soto la Marina River. Further examples include I. pricei , with a distribution range comprising several river drainages along the Pacific slope of the Sierra Madre Occidental [ 20 ], and I. dugesii , for which two differentiated western populations have been proposed [ 17 ]. On the other hand, there is some controversy regarding species synonymies; Miller et al, [ 17 ] consider two synonymized species: Ictalurus ochoterenai de Buen, 1946 with I .…”

Multi-locus phylogeny and species delimitation in the catfish genus Ictalurus Rafinesque, 1820 (Actinopterygii, Siluriformes)

“…Another differentiated group was represented by the specimens of Ictalurus aff. pricei from Culiacan/San Lorenzo rivers, con rming previous morphological ndings that indicated this population as a potential undescribed taxon (21). Similarly, the specimens of Ictalurus sp.…”

“…A total of 187 individuals of the genus Ictalurus were sampled, including members of all recognized species, according to Lundberg (2) and Miller et al (18). Sampling also included several populations recognized as undescribed taxa (2,(18)(19)21), other poorly studied populations, and three species previously synonymized (2) (Fig. 1; Table 1 and S1).…”

“…Such is the case of Ictalurus lupus (2,(19)(20), which occurs along the extensive Bravo River basin and other independent drainages along the Gulf of Mexico slope, such as the Cuatro Cienegas valley and the Soto la Marina River. Further examples included I. pricei, the distribution range of which comprises several river drainages along the Paci c slope of the Sierra Madre Occidental (21), and I. dugesii, for which two differentiated western populations have been proposed (18). Based on the above, and following assessment of the most complete taxon sampling of the described and putatively undescribed forms of Ictalurus, the present study was conducted in order to generate data with which to infer the molecular phylogenetic relationships among species of Ictalurus, to explore their biogeographical evolutionary history across North American river drainages, and to resolve certain taxonomic uncertainties relating to the genus.…”