Cabdio crassus, a new species of cyprinid fish (Teleostei: Cyprinidae) from the Kaladan River of Mizoram, India

Cabdio crassus, a new fish species, is described from the Kaladan River in Mizoram, India. The new species is distinguished from all its congeners by having a ventral keel extending from the middle of the chest, between the posterior base of the pectoral fin and along the abdomen up to the anus (vs. more or less keeled median scales from mid-point of abdomen between posterior base of pelvic fin up to anus in all other Cabdio) and 11½–12½ branched anal-fin rays (vs. 7 in C. jaya and 9 in both C. morar and C. ukhrulensis). It is further distinguished from C. morar and C. ukhrulensis by possessing more lateral-line scales (45–51 vs. 38–42 in C. morar and 35–37 in C. ukhrulensis), more predorsal scales (20–23 vs. 17–18 in C. morar and 14 in C. ukhrulensis) and more lateral transverse scales (½7/1/3½ vs. 5/1/2 in both C. morar and C. ukhrulensis). It also differs from C. jaya in having fewer lateral-line scales (45–51 vs. 52–60), more lateral transverse scales (½7/1/3½ vs. 5/1/3) and more pharyngeal tooth-rows (3 vs. 2). Furthermore, the cytochrome c oxidase sub unit I (coi) gene sequence separates Cabdio crassus from all other Cabdio species (interspecies distance ranges from 7.8–12.3%). The anomalies observed among the GenBank sequences of the genus Cabdio are discussed and resolved.

Additions to the description, reproduction and systematic position of the enigmatic species Acritagasyllis longichaetosus Lucas, San Martín & Sikorski, 2010 (Annelida: Phyllodocida: Syllidae)

We present some additional information to Acritagasyllis longichaetosus Lucas, San Martín & Sikorski 2010, the only representative of an enigmatic genus of Syllidae from subpolar areas off Norway, based on two newly found specimens and one male and another female stolons. The armature of the pharynx was incorrectly interpreted in the original description, having in fact a trepan instead of a single pharyngeal tooth as originally described. The reproductive stolons are herein described for the first time. With this new information we performed a maximum parsimony phylogenetic analysis that placed this genus within the subfamily Autolytinae, despite its peculiar morphological characteristics. For this reason, we propose a new diagnosis to the genus Acritagasyllis as well as a modified diagnosis of the subfamily Autolytinae.

Making teeth to order: conserved genes reveal an ancient molecular pattern in paddlefish (Actinopterygii)

Ray-finned fishes (Actinopterygii) are the dominant vertebrate group today (+30 000 species, predominantly teleosts), with great morphological diversity, including their dentitions. How dental morphological variation evolved is best addressed by considering a range of taxa across actinopterygian phylogeny; here we examine the dentition of Polyodon spathula (American paddlefish), assigned to the basal group Acipenseriformes. Although teeth are present and functional in young individuals of Polyodon , they are completely absent in adults. Our current understanding of developmental genes operating in the dentition is primarily restricted to teleosts; we show that shh and bmp4 , as highly conserved epithelial and mesenchymal genes for gnathostome tooth development, are similarly expressed at Polyodon tooth loci, thus extending this conserved developmental pattern within the Actinopterygii. These genes map spatio-temporal tooth initiation in Polyodon larvae and provide new data in both oral and pharyngeal tooth sites. Variation in cellular intensity of shh maps timing of tooth morphogenesis, revealing a second odontogenic wave as alternate sites within tooth rows, a dental pattern also present in more derived actinopterygians. Developmental timing for each tooth field in Polyodon follows a gradient, from rostral to caudal and ventral to dorsal, repeated during subsequent loss of teeth. The transitory Polyodon dentition is modified by cessation of tooth addition and loss. As such, Polyodon represents a basal actinopterygian model for the evolution of developmental novelty: initial conservation, followed by tooth loss, accommodating the adult trophic modification to filter-feeding.

Petroleuciscus esfahani, a new species of fish from central Iran (Actinopterygii: Cyprinidae)

A new species, Petroleuciscus esfahani, is described from central Iran in the Zayandeh River basin. It is distinguished from other members of the genus by a combination of characters including a mode of 8 1/2 dorsal-fin branched rays, modally 10-11 1/2 anal-fin branched rays, small scales numbering 44-54 in the total pored lateral line, a modal pharyngeal-tooth formula 2.5-4.2, and total vertebrae usually 40-42. It appears to be morphologically closest to Petroleuciscus gaderanus (Gunther, 1899) that we tentatively consider as a synonym of P. ulanus (Gunther, 1899) of the Lake Orumiyeh basin in northwestern Iran.

Syllidae (Polychaeta) from the Arctic and sub-Arctic regions

A collection of over one hundred specimens of Syllidae (Polychaeta) from the Arctic and sub-Arctic regions has been examined and identified. The specimens were obtained from 26 stations in the Barents Sea, some Norwegian fiords and localities of the northern North Sea. A total of 21 species were identified; three species (Myrianida langerhansi (Gidholm, 1967), Syllides longocirrata Örsted, 1845 and Sphaerosyllis taylori Perkins, 1981) are new reports for the Arctic Ocean; 2 species are new to science, Streptodonta exsulis sp. nov. and Trypanosyllis troll sp. nov. Streptodonta exsulis sp. nov. have 4 thick, distally strongly knobbed aciculae on each anterior parapodia, shifting to a single, slender acicula on posterior parapodia; falcigers and pseudospinigers distally bidentate; and pharyngeal tooth located centrally and relatively close to anterior rim of pharynx. Trypanosyllis troll sp. nov. have 2, occasionally 3 straight aciculae in parapodia protruding out from parapodial lobes; falcigers bidentate; and body surface densely covered by numerous, small papillae. Based on the description of these 2 new species, some modifications are proposed in the diagnoses of the genera Streptodonta San Martín & Hutchings, 2006 and Trypanosyllis Claparède, 1864.

Development of the pharyngeal dentition of two herbivorous halfbeaks (Teleostei : Hemiramphidae) and implications for the hemiramphid ontogenetic trophic shift

Development of the pharyngeal dentition of two herbivorous halfbeaks, Hyporhamphus regularis ardelio (Whitley, 1931) and Arrhamphus sclerolepis krefftii (Steindachner, 1867), was examined quantitatively to assess features that might confer their ability to shift their diet from animal to plant material. Toothed area, tooth number, maximum tooth diameter and tooth wear area in both pharyngeal tooth pads of both taxa increased with ontogeny, whereas tooth density decreased. Comparing individuals of the two taxa at similar standard lengths indicated that A. sclerolepis krefftii showed hypertrophy of the majority of pharyngeal characters in relation to H. regularis ardelio of a similar standard length. That A. sclerolepis krefftii is more developmentally advanced than H. regularis ardelio in almost all dentigerous characters studied indicates that pharyngeal development may allow the former to commence herbivory at a smaller standard length than the latter species. The evolutionary and ecological implications of these findings are discussed in the context of a group of fishes that is overexploited worldwide.