Nandid and badid fishes

17 p. : ill. ; 26 cm.Includes bibliographical references (p. 14-17)

Intermuscular bones in acanthomorphs

25 p. : ill. ; 26 cm.Includes bibliographical references (p. 24-25).Myosepta of selected representatives of the following acanthomorph taxa were investigated: Polymixiiformes, Lampridiformes, Paracanthopterygii, Beryciformes, Atherinomorpha, and Percomorpha. A new technique, microdissection of alcohol-stored specimens and polarized-light microscopy, was applied to study the three-dimensional architecture of connective tissue fibers in epaxial parts of myosepta. Several invariable similarities were present in all taxa: an epineural series of tendons or bones and a tendinous series of lateral bands in the epaxial part of the myoseptum, and an epicentral series of tendons or bones in the horizontal septum. Patterson and Johnson's (1995) hypothesis that the single bony series of intermusculars in higher acanthomorphs is the homolog of epineurals of lower teleosts is tested. Our results contradict their hypothesis at essential points because we discovered epineural tendons in the normal epaxial position in different acanthomorphs that were considered to lack these. We conclude that the first intermuscular bone of Polymixia is an epicentral, the single series of intermuscular bones of Holacanthopterygii are epicentrals, and the neoneurals of some percomorphs are normal epineurals. Phylogenetic implications of our results are discussed

Skeletal ontogeny of Indostomus

43 p. : ill. (some col.) ; 26 cm.Includes bibliographical references (p. 36-37).On the basis of an ontogenetic series of Indostomus paradoxus, we test characters that have been proposed for the phylogenetic placement of this enigmatic taxon. Contrary to previous authors, we found that the body armor of Indostomus differs from that of syngnathoids greatly and it closely resembles that of gasterosteoids in many unique details. The body plates originate from two different sources, that is, the endoskeleton (proximal-middle radials of dorsal and anal fin, neural and hemal spines, pelvic cartilages) and the exoskeleton (postcleithra, lateral body plates, sternal plate). The median bone in the ethmoid region develops from two centers and most likely represents the nasal bones that fuse during ontogeny with each other and with the vomer. Identity of the opercular bones is clarified, and it is demonstrated that Indostomus has an interopercle. The single pterygoid bone is the ectopterygoid. A parietal is lacking. There is only one cartilaginously preformed hypural element in the caudal fin. There is no parhypural, but a similar structure, termed the pseudoparhypural by us, develops as membranous outgrowths of the single hypural and the ural centrum. The pectoral radial plate fuses to the scapulocoracoid cartilage, and the pectoral radials ossify within that fused plate without prior fragmentation of the plate into individual radials, being specializations of the pectoral girdle that we think to be shared with all gasterosteoids. Indostomus shares with other gasterosteiforms the modification of the tripartite occipital condyle into an articulation of the basioccipital and the first centrum through loss of the articulation between exoccipitals and the first centrum in all developmental stages. Indostomus lacks distal radials in all pterygiophores supporting fin spines at all developmental stages, a character shared with other gasterosteiforms, mastacembelids, and probably other smegmamorphs. We conclude that Indostomus is a gasterosteoid gasterosteiform

The quadrate-metapterygoid fenestra of otophysan fishes, its development and homology

We compare the ontogeny of the hyopalatine arch in representatives of the Otophysi to shed light on the homology of the so-called quadrate-metapterygoid fenestra, QMF. Described initially as a character of characiforms (tetras and allies), presence of a QMF has also been reported for cobitid loaches and a handful of cyprinids among cypriniforms, as well as for a few clupeoids. In characiforms the QMF is either already present as an opening in the palatoquadrate cartilage in the earliest developmental stages we studied, or it forms later in the cartilage by resorption of chondrocytes. Some characiforms may lack a QMF during all stages of development. In cobitids the so-called QMF develops after the bones have ossified and forms mainly by resorption of bone tissue of quadrate and metapterygoid. Previous reports of a QMF in cyprinids are erroneous and the opening in this area forms by spatial separation of the quadrate and metapterygoid from the symplectic and not by the formation of a fenestra in the palatoquadrate cartilage. We suggest referring to this type as a quadrate-metapterygoid gap, QMG. Presence of a QMF in the palatoquadrate cartilage is a putative synapomorphy of characiforms. Development of a QMF by bone resorption in the ossified palatoquadrate is a putative synapomorphy of Cobitidae. A QMG is variously present and developed to different degrees in opsariichthyine and danionine cyprinids. A QMF is also present in several clupeoids and deserves further study

Evolution in the dark: Unexpected genetic diversity and morphological stasis in the blind, aquifer-dwelling catfish Horaglanis

The lateritic aquifers of the southern Indian state of Kerala harbour a unique assemblage of enigmatic stygobitic fishes which are encountered very rarely, only when they surface during the digging and cleaning of homestead wells. Here, we focus on one of the most unusual members of this group, the catfish Horaglanis, a genus of rarely-collected, tiny, blind, pigment less, and strictly aquifer-residing species. A six-year exploratory and citizen-science backed survey supported by molecular phylogenetic analysis reveals novel insights into the diversity, distribution and population structure of Horaglanis. The genus is characterized by high levels of intraspecific and interspecific genetic divergence, with phylogenetically distinct species recovered above a 7.0% genetic-distance threshold in the mitochondrial cytochrome oxidase subunit 1 gene. Contrasting with this deep genetic divergence, however, is a remarkable stasis in external morphology. We identify and describe a new cryptic species, Horaglanis populi, a lineage that is the sister group of all currently known species. All four species are represented by multiple haplotypes. Mismatch distribution reveals that populations have not experienced recent expansions

Ultrafast sound production mechanism in one of the smallest vertebrates

Motion is the basis of nearly all animal behavior. Evolution has led to some extraordinary specializations of propulsion mechanisms among invertebrates, including the mandibles of the dracula ant and the claw of the pistol shrimp. In contrast, vertebrate skeletal movement is considered to be limited by the speed of muscle, saturating around 250 Hz. Here, we describe the unique propulsion mechanism by which Danionella cerebrum, a miniature cyprinid fish of only 12 mm length, produces high amplitude sounds exceeding 140 dB (re. 1 µPa, at a distance of one body length). Using a combination of high-speed video, micro-computed tomography (micro-CT), RNA profiling, and finite difference simulations, we found that D. cerebrum employ a unique sound production mechanism that involves a drumming cartilage, a specialized rib, and a dedicated muscle adapted for low fatigue. This apparatus accelerates the drumming cartilage at over 2,000 g, shooting it at the swim bladder to generate a rapid, loud pulse. These pulses are chained together to make calls with either bilaterally alternating or unilateral muscle contractions. D. cerebrum use this remarkable mechanism for acoustic communication with conspecifics

Unraveling a 146 Years Old Taxonomic Puzzle: Validation of Malabar Snakehead, Species-Status and Its Relevance for Channid Systematics and Evolution

The current distribution of C. diplogramma and C. micropeltes is best explained by vicariance. The significant variation in the key taxonomic characters and the results of the molecular marker analysis points towards an allopatric speciation event or vicariant divergence from a common ancestor, which molecular data suggests to have occurred as early as 21.76 million years ago. The resurrection of C. diplogramma from the synonymy of C. micropeltes has hence been confirmed 146 years after its initial description and 134 years after it was synonymised, establishing it is an endemic species of peninsular India and prioritizing its conservation value

Chaudhuria ritvae Britz, 2010, new species

<i>Chaudhuria ritvae</i> new species <p>(Figures 1a,c,d,e; 2a; 3a,b)</p> <p> <b>Holotype.</b> BMNH 2010.7.21.1, 39.3 mm SL; Myanmar: Ayeyarwaddy Division: Hmoain pool, 7.5 miles southwest from Einme, Ayeyarwaddy River Drainage, 16° 47' 51" N, 95° 04' 4" E, 15 March 2003, R. Britz & R. Roesler.</p> <p> <b>Paratypes.</b> BMNH 2010.7.21.2-9, 8, 33.2–40.0 mm SL; same data as holotype. BMNH 2010.7.21.68-71, 4 (c&s), 33.0– 39.8 mm SL; same data as holotype. USNM 398655, 4, 34.8-37.4 mm SL; same data as holotype.</p> <p> <b>Diagnosis.</b> <i>Chaudhuria ritvae</i> differs from <i>C. caudata</i> by possessing a greater number of caudal vertebrae (46–49 vs. 42–45), a smaller mouth with the posterior angle of the lips situated in front of vertical through anterior margin of posterior nostril (vs. reaching vertical through anterior margin of eye), broad and large ribs (vs. narrow and small), neural arches of vertebrae without fenestration (vs. with fenestration), absence of spots associated with base of dorsal and anal fin rays (vs. presence), body pigmentation sparse, consisting of only minute widely separated melanophores (vs. body pigmentation well-developed consisting of numerous densely distributed melanophores that form lines or blotches), and absence of pigmentation along pectoral-fin rays (vs. rows of melanophores lining pectoral-fin rays). It differs from its only other congener, <i>C. fusipinnis</i>, by having the dorsal and anal fins separate from the caudal fin (vs. confluent with caudal fin), by a smaller number of dorsal- (40-43 vs 44-48) and anal-fin rays (40-43 vs. 44-48), by a greater number of caudal-fin rays (4+4 vs. 3+3) and by the presence of teeth on hypobranchial 3 (vs. teeth absent).</p> <p> <b>Description.</b> General body shape as in Figure 1a. Selected morphometric data are listed in Table 1.</p> <p>Holotype Range Mean St. Dev. SL in mm 39.3 33.2–40.0 36.3 2.1</p> <p>in percent of SL</p> <p>Body depth at anal fin origin 5.3 5.3–6.0 5.6 0.3 Head length (HL) 12.7 12.1–12.8 12.5 0.3</p> <p>in percent of HL</p> <p>Eye diameter 10.0 9.6–11.6 10.6 0.8 Snout Length 22.0 21.3–23.3 22.2 0.8 Body elongate, eel-like (Fig. 1a), greatest depth at dorsal-fin origin, 16.6 to 20.0 times in SL. Dorsal and ventral profile more or less straight in abdominal and anterior caudal region, after which body tapers towards tail. Body anteriorly round in cross section, laterally compressed in caudal region. Head elongate, cylindrical, 7.6 to 8.3 times in SL; eye small, situated dorsolaterally in anterior third of head, covered by skin (Fig. 1c –d, 2a); mouth terminal, snout short, rounded, its length contained 4.3 to 4.7 times in head length; tube of anterior nostril short, situated at tip of snout, projecting slightly from it (Fig. 1c –d, 2a). Lips fleshy, well-developed on upper and lower jaws; posterior corner where lips join situated in front of vertical through anterior margin of posterior nostril (Fig. 2 a). Postorbital part of head elongate, with 6 long branchiostegal rays supporting prominent gill membrane covering base of pectoral fin. Scales and lateral line canals absent, therefore myomeres and myosepta along body visible (Fig. 1 e).</p> <p>Dorsal and anal fins long, separate from caudal fin. Dorsal-fin rays 40 (1), 42 (1) or 43 (2). Anal-fin rays 40 (1), 42 (2) or 43 (1). Caudal-fin rays 4+4 (4). Pectoral-fin rays 7(2), 8 (1) or 10(1). Pelvic fin absent. Total number of vertebrae 74 (2), 75 (1), or 76 (1), comprising 27 (3) or 28 (1) abdominal and 46 (1), 47 (1), 48 (1) or 49 (1) caudal vertebrae.</p> <p> Head skeleton very similar to that described for <i>C. caudata</i> from Thailand in detail in Britz & Kottelat (2003). Jaws with two to three rows of small, pointed, conical, recurving teeth (Fig. 3 a). Posterior end of maxilla in front of vertical through lateral ethmoid. Exoccipitals separated in the dorsal midline by supraoccipital. Small epicentral on both sides of vertebra 1 (2), on left side only (1), or absent (1). Neural arches of vertebrae without any fenestration, but rather showing small round depressions or openings (Fig. 3 b). Abdominal vertebrae with median triangular process of membrane bone coming off roof of neural arch. Well-developed stout ribs (Fig. 3 b) on vertebrae 4-26 (1), 4-27 (1) or 4-28 (2). First dorsal-fin pterygiophore inserted behind neural spine of vertebra 25 (1) or 26 (3), last dorsal-fin pterygiophore inserted behind neural spine of vertebra 66 (2), 67 (1) or 68 (1). Anal-fin pterygiophores in front of first haemal spine 2 (1) or 3 (3). Last anal-fin pterygiophore inserted behind haemal spine of vertebra 67 (3) or 68(1).</p> <p> <b>Colouration.</b> In alcohol body light cream with numerous minute black spots on head and sparsely scattered minute spots along rest of body (Figs. 1a, 1c –e, 2a). All median fins and pectoral fins, unpigmented, translucent.</p> <p> <b>Distribution.</b> The type series was collected from Hmoain pool near Einme in the Ayeyarwaddy delta region (Fig. 4), although the species can be expected to occur in other areas of the river delta. <b>Etymology.</b> Named after my wife Ritva Roesler, who helped collect the species, honouring her continuing support of my work on Myanmar freshwater fishes.</p> <p> <b>Habitat.</b> At the time of collection Hmoain pool was ca 20 m long, up to 1 m deep and 4 m wide, with very dense aquatic vegetation consisting of <i>Nelumbo</i> and <i>Eichhornia</i> (Fig. 5). The water was clear, with a temperature of 29°C and a pH of 7.1 and the bottom was muddy. This pool is located in the Ayeyarwaddy delta floodplain at about 15 m above sea level. It is also the type locality of <i>Parasphaerichthys lineatus</i>, the exact location of which was not known at the time of description (Britz & Kottelat 2002). Among the other fish species in the pool were also <i>Dario hysginon</i> and <i>Indostomus paradoxus</i>, which have so far only been recorded from the Myitkina and Indawgyi area, with the exception of a single locality for <i>D. hysginon</i> east of Mandalay (Kullander & Britz 2002). Their occurrence in southern Myanmar thus extends their distribution considerably. The effect on the type locality of the cyclone Nargis, which hit the Ayeyarwaddy delta on 2 May 2008, is unknown, but expected to be considerable.</p>Published as part of <i>Britz, Ralf, 2010, A new earthworm eel of the genus Chaudhuria from the Ayeyarwaddy River Drainage, Myanmar (Teleostei: Synbranchiformes: Chaudhuriidae), pp. 62-68 in Zootaxa 2571</i> on pages 63-66, DOI: <a href="http://zenodo.org/record/197405">10.5281/zenodo.197405</a&gt

Dario kajal, a new species of badid fish from Meghalaya, India (Teleostei: Badidae)

Britz, Ralf (2013): Dario kajal, a new species of badid fish from Meghalaya, India (Teleostei: Badidae). Zootaxa 3731 (3): 331-337, DOI: 10.11646/zootaxa.3731.3.