Procurrent Rays Research Articles

A new and threatened species of Listrura (Siluriformes: Trichomycteridae), a rare catfish from an Atlantic Forest continental island

Abstract Listrura is a genus of small pencil catfishes of Trichomycteridae that currently comprises 12 valid species in coastal drainages of Southern and Southeastern Brazil, all with fossorial dwelling habitats and eel-like morphology. Here, we describe a new species of Listrura known from only two specimens collected in an interval of 24 years in order to make it taxonomically available for biodiversity inventories and conservation decisions. The new species is morphologically distinguished from its congeners by the combination of features, as pectoral-fin rays counts, number of free vertebrae, number caudal-fin procurrent rays, interopercular odontodes counts and the anterior-most position of dorsal and anal fin. Partial sequences of the mitochondrial gene cox1 were used to infer the phylogenetic relationships and biogeography of the new species and its congeners. The new species is the first freshwater fish endemic to a continental island in the Atlantic Forest Biome, and only the second trichomycterid endemic of an island.

Glyptothorax siangensis, a New Species of Catfish (Sisoridae) from the Brahmaputra River Drainage, Arunachal Pradesh, India

Glyptothorax siangensis, new species, is described from the Siang River in Arunachal Pradesh, India. The new species can be distinguished from its congeners from the Ganga-Brahmaputra drainage and its neighbouring drainages by the following combination of characters: a thoracic adhesive apparatus with skin ridges present over almost the entire apparatus, including the sword-shaped median depression, which is narrowly opened posteriorly; an elongated dorsal spine distinctly greater than body depth at its origin, posteriorly serrated with 11–17 serrae; nuchal plate saddle-like with W-shaped extensions; shallow body depth; long nasal barbel, almost reaching the anterior margin of eye; a complete longitudinal black band across the distal half of dorsal-fin; and tips of neural spines extension visible as a row of ridges between dorsal-fin base and origin of procurrent rays of caudal-fin. This is the nineteenth species of Glyptothorax known from the Ganga-Brahmaputra drainage.

New Species of the Damselfish Genus Chromis (Pomacentridae) from Vietnam

A new species, Chromis oligactis from the coast of Khanh Hoa province (Vietnam, South China Sea) has been described, which is characterized by a moderately deep body (contained 2.2 times in the standard length), fin formula D XIV, 10; A II, 10; P i, 15–16; three spiniform procurrent rays of the caudal fin, 26 gill-rakers in the outer row on the first arch, and 19 perforated scales in the anterior lateral line. The holotype of the new species was caught at shallow depths, which is not typical for Indo-Pacific species of Chromis with 14 spinous rays in the dorsal fin.

A new sexually dichromatic miniature Characidium (Characiformes: Crenuchidae) from the rio Guaporé, rio Madeira basin, Brazil, with remarkable morphological novelties to the genus

Abstract A new miniature species of Characidium is described from the midde rio Guaporé, rio Madeira basin, Rondônia, Brazil. The new species can be readily distinguished from all congeners by the sexual dichromatism, with females having narrow dark bars on body absent in males, and by the presence, in both sexes, of a black midventral dashed line extending from area between contralateral pectoral fins to at least the anal-fin origin. It can also be diagnosed from congeners by having strongly tricuspid teeth, with well developed and similar sized cusps in the premaxilla and outer series of dentary, and short lateral line with 6–8 perforated scales. Morphological novelties to Characidium observed in the new species include a rounded process on the first pleural rib near the vertebra, three or four haemal spines of the first caudal vertebrae distinctly elongate, neural and haemal spines of the antepenultimate vertebra not reaching origins of dorsal and ventral procurrent rays nor the origin of the caudal-fin rays.

Taxonomic significance of vertebral column and caudal skeleton of clupeid fishes (Teleostei: Clupeiformes) of Iran

AbstractClupeiformes (generally known as herrings, shads and sardines) with a synapomorphy of recessus lateralis are globally distributed marine, freshwater and diadromous species classified in seven families including the family Clupeidae. In this study, a comparative analysis of the vertebral column and caudal skeleton of twelve clupeid species was conducted on the basis of X‐ray imaging and usual staining method of bones and cartilages. Several osteological features including number of principal branched caudal rays bearing with hypurals on both lobes of the caudal‐fin; number, length, arrangement and shape of epural bones; shape and length of haemal and neural spines of the penultimate vertebrae 2, 3 and 4; length and shape of parhypural; length and shape of neural arch of the urostyle; distribution of the dorsal and procurrent rays, and fusion of parhypural with preural centrum 1 (PU1) were investigated and a detailed account of these structures were provided. The results reveal that the neural spine of the 2nd, 3rd and 4th penultimate vertebrae (NSPU2, NSPU3 and NSPU4) was generally narrow and broad in lower and pointed at upper part with some variation in the size and position related to the dorsal edge of the body in different taxa. The neural arch of the urostyle (Na) has been observed as spindle, lance‐like or knife‐like. It is usually long (≥1/2 length of the NSPU2) with some modification in the studied species. Two or three curved, straight, cone‐shape or pin‐shaped epurals were found in all species with the same number in congeneric species. Opisthural cartilage (O) lays between HYP6 and PLS anteriorly, located at the tip of PLS or traversed horizontally. The presence of this cartilage made a gap between first (longest) and second unbranched caudal rays in upper part of caudal‐fin. It showed six varied shapes (e.g. fusiform, golf club‐like, horn shape, trapezoid shape, crescent and triangle) with different size in comparison with HYP6. This comparative study revealed that some osteological characters such as shape and position of opisthural cartilage, shape of neural arch of the urostyle, and number of epurals could be used as suitable features for the identification of the studied clupeids at the species and genus levels. The improved knowledge of the skeletal structures provided here, can also facilitate the correct identification of clupeid fossils.

A new species of Cambeva (Siluriformes, Trichomycteridae) from the Rio Ivaí basin, Upper Rio Paraná basin, Paraná State, Brazil.

A new species of Cambeva endemic to the Rio Ivaí basin, Upper Paraná basin, is described combining morphological and molecular data. This new species is distinguished from all congeners by characters related to the number of pectoral-fin rays, to the colour pattern of the dorsal and lateral surface of the body, to the presence of diffuse blotches in the ventral surface of body, to the presence of a pelvic-fin and pelvic girdle, to the number of odontodes in the inter-opercular and opercular patches, to the number of dorsal and ventral procurrent rays. In addition, the analysis of mitochondrial DNA sequences identified a satisfactory genetic distance between this new species and its congeners. The new species from the Rio Ivaí reinforces its characteristics as an area of endemism for fishes in the Upper Rio Paraná basin.

Paraliparis variabilidens, a new snailfish (Liparidae) from the Suruga Trough, Japan

The new snailfish Paraliparis variabilidens is described from a single specimen collected between 1,462 and 1,562 m depth in the northern part of the Suruga Trough, Japan. It differs from all currently recognized congeners by the following combination of characters: 67 total vertebrae, 62 dorsal-fin rays, 57 anal-fin rays, 26 or 27 pectoral-fin rays, 9 caudal-fin rays (including 2 procurrent rays), ca. 12 pyloric caeca, mixed simple and trilobate teeth on both jaws, eye diameter 18.1% HL, gill slit extending ventrally in front of 2nd pectoral-fin ray base, deeply notched pectoral fin, body dusky, peritoneum black, and stomach pale.

Chromis tingting, a new species of damselfish from mesophotic coral ecosystems of southern Japan, with notes on C. mirationis Tanaka (Teleostei: Pomacentridae).

Chromis tingting sp. nov., is described on the basis of the holotype and three paratypes from Sagami Bay, Japan. The new species likely belongs to a complex consisting of C. mirationis, C. okamurai and C. struhsakeri, with which it shares the following character combination: dorsal rays XIV,13-14; anal rays II,12; pectoral rays 19-20; tubed lateral-line scales 15-17; two spinous procurrent rays dorsally and ventrally in the caudal fin; and a generally silvery white adult coloration. The new species differs from the other members of its complex in coloration details (particularly in juvenile coloration), and in having fewer gill rakers (5-6 + 17-20 = 22-26), and a larger eye -(13.7-19.4 % SL). The new species has previously been confused with Chromis mirationis, and the contention is herewith briefly discussed.

A new pearleye (Teleostei, Aulopiformes) species from the Oligocene of Romania

A new pearleye species of the alepisauroid family Scopelarchidae, Scopelarchoides neamticus sp. nov., is described herein based on two specimens from the Oligocene Lower Dysodilic Shales Formation, cropping out in the Pietricica Mountain, Romanian Eastern Carpathians. The new species described herein exhibits a unique combination of features (including head length about 25% of SL; coracoid remarkably expanded; both preorbital and postorbital lengths larger than orbit diameter; 50 or 51 vertebrae; dorsal fin with nine or ten rays; anal-fin with 28 rays; length of anal fin base about 30% of SL; preanal distance almost 60% of SL; pelvic fin insertion located just under the second dorsal fin ray; pectoral fins only slightly longer than pelvic fins; caudal fin with 19 principal rays plus 14 upper and 13 lower procurrent rays) that justifies its recognition as a new species of the genus Scopelarchoides. Both morphological and meristic features suggest a certain degree of similarity between S. neamticus sp. nov. and the extant species Scopelarchoides signifer. The fossils of the new Oligocene species described herein represent the oldest known skeletal record of Scopelarchidae.

Recently diverged killifishes: Morphometry and caudal skeleton osteology of two members of the Aphanius dispar species group (Aphaniidae, Teleostei)

Recently diverged killifishes: Morphometry and caudal skeleton osteology of two members of the Aphanius dispar species group (Aphaniidae, Teleostei)

A new species of the catfish genus Trichomycterus (Teleostei: Siluriformes: Trichomycteridae) from the Paraná basin, Central Brazil

Trichomycterus giarettai, new species, from a small river in Cumari municipality, Central Brazil is described. It is hypothesized to be closely related to species of T. brasiliensis complex by possessing the opercular odontodes disposed obliquely on the patch. Trichomycterus giarettai is diagnosed by the distribution of infraorbital pores, body width, caudal peduncle width, number of vertebrae, branchiostegal rays, dorsal and ventral procurrent rays, opercular and interopercular odontodes, length of the nasal barbels, and pelvic fin insertion.

A new catfish species of the Trichomycterus hasemani group (Siluriformes: Trichomycteridae), from the Branco river basin, northern Brazil

Trichomycterus wapixana is described from the Branco river basin, Roraima State, northern Brazil. It belongs to the T. hasemani group, composed of T. hasemani, T. johnsoni and T. anhanga and defined by the presence of a single wide cranial fontanel delimited by the frontal and supraoccipital, absence of the pores i1 and i3, absence of branchiostegal rays on the posterior ceratohyal and the by the presence of a large and distally expanded process on the palatine. It differs from the other species of that assemblage by having a unique combination of character states, including number of vertebrae, relative position of anal fin, relative position of pelvic and dorsal fin, presence of pelvic fin and pelvic girdle, number of dorsal and ventral procurrent rays in the caudal fin, anal-fin rays, pectoral-fin rays, branchiostegal rays, pleural ribs, morphology of palatine, presence of parasphenoid and relative position of urogenital pore.

Osteological characters of the axial skeleton and pectoral girdles in some species of the Euroasian freshwater fishes of the family Cottidae

The structure of the pectoral fin, its girdle and osteological details of the axial skeleton and a skeleton of the caudal fin, including the structure of unpaired fins were studied in three species of three genera of the family Cottidae: the genus Cottus: European species C. koshewnikowi Gratzianov, 1907 and two species of Fareastern monotypic genera: Trachidermus fasciatus Heckel, 1837 and Mesocottus haitej (Dybowsky, 1869). The species well differ in structure of the pectoral girdles and pleural ribs. Mesocottus haitej is characterized by absence of the interradial and coracoid fenestrae and by considerable reduction of pleural ribs in the abdomen part of the vertebral column. Сottus koshewnikowi and T. fasciatus have backwardly directed pleural ribs (3 pairs of ribs in M. haitej). Trachidermus fasciatus is characterized with the most number of plesiomorphic features: the presence of branched rays in the pectoral fin, greater numbers of vertebrae, rays in the second dorsal, anal and pectoral fins, big anteanal distance and by number of preural vertebrae, supporting the procurrent rays. In C. koshewnikowi, the first dorsal fin occupies the most anterior position: aID 32.6–38.0% SL vs 35.7–38.7% SL in T. fasciatus and 36.4–40.8% SL in M. haitej.

Osteological characteristics of Turkmenian stone loach, Paraschistura cristata (Cypriniformes: Nemacheilidae)

Formerly the Turkmenian stone loach was the only member of the genus Metaschistura based on osteological characters. But recently, it is placed in the genus Paraschistura based on mtDNA COI data. To provide a detailed description of the osteological characteristics of Paraschistura cristata (Berg 1898), ten specimens of P. cristata were collected from the Hari River basin in Iran and their osteological characteristics were examined. According to the results, P. cristata is osteologically characterized by a foramen in the ventral part of the exoccipital, two extra urohyals, sesamoid ossifications, trapezoid-shaped prevomer, three basibranchials, five hypural, lack of bony bridge between the parietal and pterotic, having over 20 procurrent rays supporting the adipose crest. The detailed skeletal description of P. cristata showed that this species can be easily distinguished from the related genera. Despite the mtDNA COI result, the osteological data of this species showed some features to describe it as a distinctive genus, but this needs the osteological data of the all other Paraschistura species to be compared.

A new species of the clingfish genus Kopua (Gobiesociformes: Gobiesocidae) from Japan

A new clingfish, Kopuavermiculata, is described on the basis of a single specimen collected from ca. 100 m depth off the Pacific coast of Honshu Island, Japan. The new species is distinguished from its congeners by having the following characters: dorsal fin rays 7; anal fin rays 6; segmented caudal fin rays 15; upper procurrent caudal rays associated with both neural spine of second preural centrum and epural; vertebrae 35; nasal pores 1; lacrymal pores 3; mandibular pores 3; predorsal length about 60 % of standard length; body whitish with distinct reddish-orange blotches on body; no reddish-orange stripes on cheek; belly whitish. A key to the species of Kopua is provided.

Population, sex, and ontogenetic differences in the procurrent rays of the caudal fin in threespine sticklebacks (Gasterosteusaculeatus)

The procurrent rays occur at the leading edge of the caudal fin in bony fishes and are taxonomically variable and possibly important to caudal motion. Using radiographs, as well as stained and cleared specimens, of threespine sticklebacks (Gasterosteus aculeatus L., 1758) from lakes on Haida Gwaii, British Columbia, we examined the extent of individual and population variabilities in these rays. Among 1113 fish from Drizzle Lake, 53% of individuals were dorsoventrally asymmetric in number of rays of which 95% had greater number of rays on the dorsal lobe. On 274 fish, we also quantified dorsal to ventral (D/V) ratios of the width of the most posterior procurrent rays and found ontogenetic shifts with symmetrical D/V ratios in subadults shifting to significant dorsal biases on the larger fish (60–90 mm standard length (SL)). Males have proportionally greater dorsal bias than females of equivalent size in both number and width of procurrent rays. We examined D/V width ratios in 105 stained and cleared specimens from 13 additional allopatric lake populations on Haida Gwaii. Eight populations were symmetrical for width of dorsal and ventral rays, while three populations were ventrally biased and two populations were dorsally biased. D/V ratios were best predicted by positive associations with adult body size and negative associations with total number of gill rakers.

A new stem fossil characid (Teleostei: Ostariophysi) from the Eocene-Oligocene of southeastern Brazil

A new characiform is herein described from the Eocene-Oligocene sediments exposed in the Aiuruoca basin, in southern Minas Gerais State, Brazil. Recently, two other characid species were described for this same fossil level: †Paleotetra aiuruoca and †Paleotetra entrecorregos. The holotype of this new characiform is represented by an articulated specimen preserved as part and counterpart, in which the most anterior part of the head is missing, including the jaws. Despite the lack of the diagnostic characters from the snout, a unique combination of characters allows its differentiation from other Neotropical characiforms, raising a new genus and species: †Bryconetes enigmaticus. Among these characters are: the presence of a supraorbital, dentary with inflated pentacuspidate teeth arranged in a single row, infraorbital 3 expanded and ornamented with punctuations and grooves, a large anal fin with iii+22-23 rays, and the caudal fin with 11 ventral procurrent rays of which the anteriormost are fused in laminar bones. A phylogenetic analysis using morphological data was performed and recovered †Bryconetes enigmaticus as a stem group to characiforms lacking a supraorbital. Based on the results of this analysis, a discussion of the potential relationships of the new taxon with other characiforms is presented.

Re-description of Trichomycterus cubataonis BIZERRIL, 1994 (Siluriformes: Trichomycteridae) from the Cubatão river basin, southern Brazil

Trichomycterus cubataonis, from the Cubatão river, southern Brazil, is re-described and revalidated. It is hypothesized as closely related to T. diabolus, T. itatiayae, T. maculosus and T. nigroautarus based on the presence of a broad metapterygoid, which is wider than deeper. Trichomycterus cubataonis differs from the above four species by the number of pectoral, dorsal, and anal-fins rays, origin of anal fin related to the dorsal-fin base, insertion of pelvic-fin related to the vertebrae, origin of dorsal- and anal fins related to the vertebrae, number of dorsal and ventral procurrent rays of caudal fin, number of odontodes of the opercular and interopercular patch, length, depth and width of the head, and eye size. Moreover, T. cubataonis differs from T. zonatus mainly by the insertion of pelvic-fin related to the vertebrae, origin of dorsal- and anal fins related to the vertebrae, number of anal fin rays, and the position of the anal fin related to the dorsal-fin base. Therefore, T. cubataonis should be considered a valid species.

Sexual dimorphism in species of Schistura (Teleostei: Nemacheilidae) from the Mae Khlong basin and peninsular Thailand

Sexually dimorphic characteristics are described for four species of Schistura from the Mae Khlong basin and peninsularThailand. Males of S. mahnerti have a suborbital flap and rows of unculi on the upper surfaces of the pectoral-fin rays.Females of S. mahnerti have a suborbital groove. None of the morphological measurements differ significantly betweenmales and females of S. mahnerti. In the other three species, S. aurantiaca, S. cf. aurantiaca, and S. sexcauda, all indi-viduals lack the flap or groove, but most males have a conspicuous black botch on the procurrent rays of the upper lobeof the caudal fin, a feature absent in most females. Some morphometric characteristics vary between sexes of these spe-cies. Sexually dimorphic traits presumably have a function related to reproduction; however, little is known about reproduction in Schistura, and variation in morphology in relation to habitat or other environmental factors has not been studied.

Growth and morphological development of laboratory-reared larval and juvenile bighead catfish Clarias macrocephalus (Siluriformes: Clariidae)

Morphological development in laboratory-reared larval and juvenile bighead catfish Clarias macrocephalus is described. Body length (BL) of larvae and juveniles was 3.4 ± 0.3 (mean ± SD) mm just after hatching, reaching 11.3 ± 1.0 mm by day 16, and 24.2 ± 2.8 mm by day 40. Overall aggregate fin ray numbers (except for caudal fin procurrent rays) attained full complements by 15.2 mm BL. Gill buds appeared on day 0, those of barbels (four pairs) and primordial nostrils on day 1, and pectoral fins on day 3. All larvae began feeding by day 3. Conical teeth were observed on day 7. Notochord flexion began on day 2, the yolk being completely absorbed during days 7–9. Melanophores were scarce at hatching, increasing with growth to cover almost the entire body except the ventral surface of the abdominal cavity. Proportions of head length, pre-anal length, body depth, eye diameter, and maxillary barbel length became relatively constant after yolk absorption, those of snout length and upper jaw length increasing until ca. 12–13 mm BL and decreasing thereafter. Suprabranchial organ started developing in postflexion larval stage larger than ca. 11.0 mm BL (day 16), and air-breathing was suggested to be functional at that time.