Spectacular morphological novelty in a miniature cyprinid fish, Danionella dracula n. sp.

Abstract

Danionella dracula is a new species of sexually dimorphic, miniature and highly developmentally truncated cyprinid fish. Compared with its close relative, the zebrafish Danio rerio , it lacks 44 bones or parts thereof and represents one of the most developmentally truncated vertebrates. Absence of the majority of bones appears to be due to developmental truncation via terminal deletion. In contrast to these larval-like features, D. dracula also shows several hyperossifications. Uniquely, among carp-like fishes, male D. dracula have a series of long, pointed odontoid processes on the jaws greatly resembling the jaw dentition of teleosts with true teeth. The anterior-most process in each jaw is extended as a canine-like fang projecting through the epithelium. True jaw teeth are absent from all 3700 species of cypriniforms and were lost at least in the Upper Eocene. It remains to be investigated, however, whether the conserved pathways to regulate tooth development in cypriniforms have been used in D. dracula to form and pattern the odontoid processes. This new species represents a remarkable example linking progenetic paedomorphosis via heterochronic change in developmental timing to the evolution of morphological novelties.

The complete mitochondrial DNA sequence of Pectenocypris sp. (Actinopterygii: Cyprinidae) from Serkap River, Sumatra, Indonesia

“…This is the first complete mitochondrial genome sequence from genus Pectenocypris. The phylogenetic tree (Figure 1) suggested that Rasbora is not monophyletic in relation to genera Trigonostigma, Pectenocypris, and Boraras, which is in agreement with earlier molecular studies (R€ uber et al 2007;Britz et al 2009;Tang et al 2010). It was also suggested that contrary to the earlier work (e.g.…”

Selection and constraint underlie irreversibility of tooth loss in cypriniform fishes

“…These genetic changes in multiple pathways likely comprise the constraint that has rendered loss of these teeth irreversible. Such a constraint would explain the appearance of bony projections from the jaw in D. dracula (18) and several lineages of fish-eating cypriniforms (12) in response to likely selection for the function provided by true oral teeth.…”

“…These piscivorous cypriniforms have been suggested to be less-efficient predators than other taxa with more extensive dentition (11,16,17). In addition, the cypriniform species Danionella dracula has evolved dramatic fangs, not by regaining oral teeth but by sculpting the shape of bones of the jaw margin (18).…”

Flexibility in starting posture drives flexibility in kinematic behavior of the kinethmoid-mediated premaxillary protrusion mechanism in a cyprinid fish,Cyprinus carpio

“…The kinethmoid is a cypriniform synapomorphy and is ubiquitous across this clade of nearly 3500 species (Simons and Gidmark, 2010), with the exception of one highly miniaturized species (Britz et al, 2009). The kinethmoid is an unpaired, midline sesamoid bone or cartilage that develops within the intermaxillary ligament (Staab and Hernandez, 2010).…”