Cranoglanis

Abstract: The genus Cranoglanis Peters is a group of fishes only distributed in East Asia. They live in the drainages of Guangdong, Guangxi, Yunnan, Hainan and the Red River drainage in northern Vietnam. At present, there are only three species in this genus, named Cranoglanis bouderius, C. multiradiatus and C. henrici. However, the described species, Cranoglanis bouderius, only based on one picture then and the name of C. multiradiatus was also depended on only three specimens. So there are still some arguments on the validity of these species. Now there is still no study related to their morphometries within these species living in different environment. This article is about the research on the species classification of Cranoglanis Peters to clarify the confusion and form a better classification. The method of morphometrics was used on 43 measurements in 66 individuals collected from Zhujiang drainage, Yuanjiang drainage and Hainan Island. Then, the principle component analysis was conducted on these variables. The preliminary analysis result indicates that there are no prominent differences among the three species, so they could not be divided into three species. They should be considered as one species: Cranoglanis bouderius.

Abstract: Figured on the following two pages are 3D models of the bony skeleton of the Asian catfish Cranoglanis bouderius, produced with High Resolution X-ray Com puted Tomography (HRXCT) imaging methods. The scanned specimen is from China, Guangdong Province Guangzhou city, and is deposited at the Academy of Natrual Sciences: ANSP 164978, Standard Length = 125 mm. Additional images and animations of this specimen are publicly available at the CatfishBones website, http:// catfishbone.acnatsci.org/. The specimen was scanned at the High-Resolution X ray CT Facility, The University of Texas, Austin. The scan ning parameters are as follows. A Feinfocus microfocal X-ray source operating at 180 kV and 0.133 mA with no X ray prefiltering. For each slice, 1600 views were taken with two samples per view. The field of image reconstruction was 40 mm, corresponding to a resolution of 39.1 microns per pixel for the 1024 by 1024 pixel slices. The specimen was scanned in multi-slice mode, in which 15 slices were collected simultaneously during a single specimen rota tion resulting in a total of 645 transverse (=coronal) CT slices. The scan was taken along the long axis of the speci men from the tip of the snout to the middle of the dorsal fin base. Visualizations were produced in the commercial software package VG Studio Max?. Although the render ings appear similar to photographs, they represent the den sity differences of the biological materials as reflected in their X-ray opacity. Preparation of the figures utilized still frames captured from digital animations of HRXCT and were prepared using Adobe?Photoshop?CS. The genus Cranoglanis, with three species, is placed in its own family Cranoglanididae. These catfishes are endemic to southern mainland China, Hainan Island and Viet Nam. The relationship of Cranoglanis to other cat fishes has long been uncertain due to its generalized mor phology. Cranoglanis has been variously thought related to Asian Bagridae, Pangasiidae or Schilbidae. However, one morphological study by Diogo et al. (2002) and recent molecular-based phylogenetic studies by Hardman (2005) and Sullivan et al. (2006) indicate a sistergroup relation ship between Cranoglanididae and the North American catfish family Ictaluridae. This discovery confirms the long-standing supposition of close evolutionary relation ship between North American and some Asian catfishes. Lundberg et al. (2007) applied fossil-calibrated molecu lar dating analyses to chart the time course of catfish di versification. They estimated the age of the phylogenet ic split between Cranoglanididae and Ictaluridae to have been roughly 85 million years ago in the Late Cretaceous when the early Bering land bridge between eastern Asian and western North America provided a migration path for biotic exchange.

Abstract: The genus Cranoglanis Peters is a group of fishes only distributed in East AsiaThey live in the drainages of Guangdong, Guangxi, Yunnan, Hainan and the Red River drainage in northern Vietnam At present,there are only three species in this genus ,named Cranoglanis bouderius , C multiradiatus and C henrici However, the described species, Cranoglanis bouderius , only based on one picture then and the name of C multiradiatus was also depended on only three specimens So there are still some arguments on the validity of these species Now there is still no study related to their morphometrics within these species living in different environment This article is about the research on the species classification of Cranoglanis Peters to clarify the confusion and form a better classification The method of morphometrics was used on 43 measurements in 66 individuals collected from Zhujiang drainage, Yuanjiang drainage and Hainan Island Then, the principle component analysis was conducted on these variablesThe preliminary analysis result indicates that there are no prominent differences among the three species,so they could not be divided into three speciesThey should be considered as one species: Cranoglanis bouderius

Abstract: We applied Bayesian phylogenetics, divergence time estimation, diversification pattern analysis, and parsimony-based methods of ancestral state reconstruction to a combination of nucleotide sequences, maximum body sizes, fossils, and paleoclimate data to explore the influence of an extrinsic (climate change) and an intrinsic (maximum body size) factor on diversification rates in a North American clade of catfishes (Ictaluridae). We found diversification rate to have been significantly variable over time, with significant (or nearly significant) rate increases in the early history of Noturus. Though the latter coincided closely with a period of dramatic climate change at the Eocene-Oligocene boundary, we did not detect evidence for a general association between climate change and diversification rate during the entire history of Ictaluridae. Within Ictaluridae, small body size was found to be a near significant predictor of species richness. Morphological stasis of several species appears to be a consequence of a homoplastic increase in body size. We estimated the maximum standard length of the ictalurid ancestor to be approximately 50 cm, comparable to Eocene ictalurids (Astephus) and similar to modern sizes of Ameiurus and their Asian sister-taxon Cranoglanis. During the late Paleocene and early Eocene, the ictalurid ancestor diversified into the lineages represented by the modern epigean genera. The majority of modern species originated in the Oligocene and Miocene, most likely according to a peripheral isolates model of speciation. We discuss the difficulties of detecting macroevolutionary patterns within a lineage history and encourage the scrutiny of the terminal Eocene climatic event as a direct promoter of diversification.