Enteromius pinnimaculatus sp. nov. (Cypriniformes: Cyprinidae) from southern Gabon

We present and describe a new species of Enteromius, adding to the 16 species of Enteromius currently recorded from Gabon, West Africa. This new species is distinguished from all other Gabonese Enteromius by the presence of several distinct spots on the dorsal fin in combination with three or four round spots on the flanks. In Africa, it is superficially similar to Enteromius walkeri and with which it shares an unusual allometry in that the proportional length of the barbels decreases as the fish grows. Nevertheless, one can distinguish these species by vertebral number, maximum standard length, the length of the anterior barbels, the length of the caudal peduncle and in most specimens, the number of lateral-line and circumpeduncular scales. These two species also inhabit widely separated drainages, with E. walkeri occurring in coastal drainages of Ghana including the Pra and Ankobra Rivers and the new species occurring in tributaries of the Louetsi and Bibaka Rivers of Gabon, which are part of the Ogowe and Nyanga drainages, respectively. Despite extensive collections in those drainages the new species is known from only two localities, suggesting the importance of conservation of its known habitat.     

A new species of electric knifefish,genus Compsaraia (Gymnotiformes: Apteronotidae) from the Amazon River,with extreme sexual dimorphism in snout and jaw length

Abstract

A new species of the neotropical electric fish genus Compsaraia is described from the western Amazon of Peru and Brazil. Compsaraia samueli is distinguishable from all other apteronotids by sexual dimorphism in which mature males exhibit extreme elongation and slenderness of the snout and jaws. Compsaraia samueli is readily distinguishable from its only congener, C. compsa, by more caudal‐fin rays (17–18 vs. 13–16), a shorter caudal peduncle (mean length 9% vs. 34% body length to end of anal fin), a less tapering body shape in lateral profile (mean ratio of body depth at origins of anal fin and dorsal organ 93% vs. 75%), and a smaller maximum adult body size (230 vs. 305 mm). The genus Compsaraia is readily separated from other apteronotids by a pale antorbital stripe and a pale L‐shaped patch over the supra‐temporal canal. The phylogenetic position of C. samueliis estimated by inclusion in a previously published data matrixof osteological and other morphological characters. Comparisons of the cranial bones in apteronotids shows the derived morphology of C. samueli to be a composite of three developmentally and phylogenetically discrete characters: (1) positive allometric growth before sexual maturity in both sexes of the pre‐orbital region of the neurocranium, (2) positive allometric growth of the (oral) jaws, and (3) secondary sexual dimorphism of snout and jaw morphology. The genus Compsaraia represents one of at least three phylogenetically independent cases of snout elongation and one of at least four cases of jaw elongation within the Apteronotidae. Compsaraia samueli also represents one of at least four cases of secondary sexual dimorphism in snout and jaw length within the Apteronotidae. The phylogenetic distribution of snout and jaw characters within the Apteronotidae suggests the influence of both sexual and trophic functional influences on the evolution of head morphology.     

Pseudobagrus brachyrhabdion, a new catfish (Teleostei: Bagridae) from the middle Yangtze River drainage, South China

Pseudobagrus brachyrhabdion sp. nov., from the Yuan Jiang and Xiang Jiang of the middle Yangtze River drainage in Hunan and Guizhou Provinces, South China, is described herein. It is distinguished from all other Pseudobagrus species with a truncate or slightly emarginated caudal fin by an unique combination of the following characters: supraoccipital plate and nuchal plate broadly interspaced and covered with skin; nasal barbels only at most reaching anterior margin of eye; maxillary barbels reaching slightly beyond posterior margin of eye; outer mandibular barbels extending to posterior margin of eye; dorsal fin with a somewhat convex distal margin, origin nearer to pectoral-fin insertion than to pelvic-fin insertion; dorsal-fin spine shorter than pectoral spine, with a somewhat serrated posterior margin; pectoral-fin spine with a smooth anterior margin; anal fin with 20–23 rays, base length 23.8–32.0% of standard length, posterior end of anal-fin base anterior to posterior end of adipose fin base; no longitudinal black band extending along flank; eyes large, diameter 16.3–23.7% of head length; and number of vertebrae 5 + 43–46.     

Redescription of a rare bothid,Asterorhombus bleekeri (Macleay), and description of a new species ofAsterorhombus from northwestern Australia (Teleostei: Pleuronectiformes)

A rare Australian bothid flounder.Asterorhombus bleekeri (Macleay), is redescribed from the holotype and ten additional specimens from the east coast of Qeensland, Gulf of Carpentaria and Rowly Shoal (Western Australia). The species is transferred fromArnoglossus Bleeker toAsterorhombus Tanaka because of the lack of obvious sexual dimorphism in the interorbital width and pectoral fin length, the lack of rostral and orbital spines, the yellow-white blind side body coloration, and the deeply cleft parhypural and hypural plates. The definition ofAsterorhombus was emended as follows: the first dorsal fin ray continuous with or separated from remaining fin rays and gill rakers slender or stubby, with or without serrations.Asterorhombus osculus sp. nov., formerly briefly described in the literature as unidentified species ofEngyprosopon, was described from eight specimens from the northwestern coast of Australia. The new species is most similar toA. bleekeri in lacking sexual dimorphism, and having the caudal skeleton with deep clefts, two or three rows of teeth on the upper jaw and a pair of conspicuous black spots on the caudal fin, in addition to a similar general appearance, but is distinguished from the latter by shorter gill rakers, a very small mouth and feebly ctenoid scales on the ocular side. Both species clearly differed fromA. intermedius andA. fijiensis in having two (or three) rows of teeth on the upper jaws, slender gill rakers without serrations, first dorsal fin ray continuous with the other fin rays, and a pair of conspicuous black spots on the caudal fin.     

New remarkable sexually dimorphic miniature species of Hyphessobrycon (Characiformes: Characidae) from the upper Rio Tapajós basin

A new miniature species of Hyphessobrycon is described from an affluent of the Rio Papagaio, tributary of the Rio Juruena, upper Rio Tapajós basin, Mato Grosso State, Brazil. The new species can be distinguished from its congeners by having a remarkable secondary sexual dimorphism in its live colouration (males are red and females yellow), well‐defined and relatively narrow dark midlateral stripe extending from tip of snout to tip of middle caudal‐fin rays, absence of humeral blotch, 15–18 branched anal‐fin rays and five or six branched pelvic‐fin rays. The sexually dimorphic colouration of the new species is briefly discussed regarding its temporal variation.     

Evidence for the secondary sexual development of the anal fin in female kokanee salmon Oncorhynchus nerka

This study examines whether the anal fin undergoes secondary sexual development similar to other reproductive traits in salmonids. This hypothesis was tested by comparing the anal‐fin size of female kokanee salmon Oncorhynchus nerka that were in the early and late stages of sexual development. Females in an advanced stage of maturation had significantly larger anal fins relative to females in an early state of maturation (+4–7%), indicating that the anal fin undergoes secondary sexual development. The magnitude of this secondary growth was comparable with snout length (+9–10%), which is known to undergo secondary sexual development in female salmonids. When morphological trait dimensions were compared between the sexes, the anal fin was the only morphological trait found to have a female‐biased sexual size dimorphism. This is the first study to show that the anal fin of female salmonids undergoes secondary sexual development.     

Review of seven-spined <Emphasis Type="Italic">Polynemus</Emphasis> species (Perciformes: Polynemidae) with designation of a neotype for <Emphasis Type="Italic">Polynemus paradiseus</Emphasis> Linnaeus, 1758

 A taxonomic review of seven-spined Polynemus species recognizes two species as valid: P. hornadayi Myers, 1936, currently known only from western Sarawak, Kalimantan, Malaysia, and P. paradiseus Linnaeus, 1758, distributed from India to Thailand and regarded as a senior synonym of P. aureus Hamilton, 1822, P. longifilis Cuvier in Cuvier and Valenciennes, 1829, P. risua Hamilton, 1822, and P. toposui Hamilton, 1822. Polynemus hornadayi differs from P. paradiseus in having a strongly protruded occipital profile (vs. nearly straight in the latter), lower counts of anal fin soft rays (mode 11 vs. 12) and gill rakers (26 vs. 32 or 33), higher counts of pectoral fin rays (18 vs. 17), scales above and below the lateral line (11 and 18 vs. 7 and 11, respectively), and pored lateral line scales (94 vs. 70), the fifth pectoral filament longest (vs. sixth), the fourth pectoral filament longer (extending well beyond the posterior central margin of the caudal fin vs. not reaching posterior central margin), a longer pectoral fin ray (posterior tip of pectoral fin reaching to midpoint of anal fin base vs. not reaching), a deeper maxilla posterior margin (mean 5% of SL vs. 4% of SL), and a well-developed swimbladder (vs. absent).     

Two new species of the sisorid Genus <Emphasis Type="Italic">Oreoglanis</Emphasis> Smith from Yunnan,China (Teleostei: Sisoridae)

Synopsis Two new species of the genus Oreoglanis, O. jingdongensis and O. immaculatus are described from the Mekong and Salween River basins, respectively, of Yunnan Province, China. Oreoglanis jingdongensis can be distinguished from other Oreoglanis species by the following characters: lower lip with a distinct median notch, posterior edge smooth or with indentations; caudal fin lunate and lower lobe longer than upper lobe. Oreoglanis immaculatus can be distinguished from its congeners by the following features: lower lip with a strait median notch, posterior edge with indentations; caudal fin emarginate and lower lobe about the same length as upper lobe, having no yellow patches on sides of body below adipose fin.     

A new sexually dichromatic miniature Hyphessobrycon (Teleostei: Characiformes: Characidae) from the Rio Formiga,upper Rio Juruena basin,Mato Grosso,Brazil, with a review of sexual dichromatism in Characiformes

Hyphessobrycon myrmex sp. nov., is described from the Rio Formiga, upper Rio Juruena, upper Rio Tapajós basin, Mato Grosso, Brazil. The new species can be distinguished from congeners by having the lower half of the body deeply pigmented with dark chromatophores, chromatophores concentrated above the anal fin and forming a broad, diffuse, dark midlateral stripe and by having a dense concentration of dark chromatophores along unbranched dorsal‐fin rays and distal portions of the two or three subsequent branched rays. In life, H. myrmex exhibits a conspicuous sexual dichromatism, with adult males red to orange and females and immatures pale yellow. A list containing 108 sexually dichromatic taxa in six families of Characiformes is provided and the distribution of this poorly known type of dimorphism across the Characiformes is discussed.     

Revision of Iquius nipponicus Jordan 1919 (Teleostei: Cyprinidae) from the Miocene of Iki Island, Nagasaki, Japan and its phylogenetic position

Iquius nipponicus Jordan 1919 was described on the basis of a single specimen from the Miocene of Iki Island, Nagasaki, Japan, and was tentatively assigned to the family Clupeidae. The holotype consists of the anterior portion of the body (lacking the anal and caudal fins and most of the caudal vertebrae), and is re-examined. The species is re-described based on additional specimens from the type locality. This species possesses an extremely stout third dorsal spine-like fin ray with a smooth posterior edge, an expanded anterior portion of the maxilla covering approximately half of the bone, 13 branched anal fin rays, and 22 abdominal and 16 caudal vertebrae. A phylogenetic study using the character matrix from a previous study suggests that the species forms a clade with xenocyprinins, but it differs from xenocyprinins in the form of the maxilla and the dentary and the numbers of branched anal fin rays and vertebrae. The present study concludes that the genus Iquius does not belong to the family Clupeidae. Iquius is a distinct and valid genus that is closely related to cultrins and xenocyprinins of the family Cyprinidae.     

A new cave-dwelling loach, Triplophysa macrocephala (Teleostei: Cypriniformes: Balitoridae), from Guangxi, China

A new cave-dwelling species, Triplophysa macrocephala sp. nov. is described based on specimens collected from a karst cave in Renguang village, Lihu Town, Nandan County, Guangxi Zhuang Autonomous Region, China. The new species can be distinguished from its congeners by possessing the following combination of characters: pectoral fin not reaching beyond pelvic-fin origin; caudal fin forked; body smooth or scaleless; dorsal-fin origin anterior to pelvic-fin origin, edge of dorsal fin truncate; dorsal fin with eight branched rays; anal fin with five branched rays; eye small and vestigial; lower jaw arched with a median notch; air-bladder wrapped in bony capsule, lateral enlarged, posterior chamber of air-bladder degenerated.     

Pseudanthias calloura (Teleostei: Perciformes), a new serranid fish from Palau, Central Pacific

A new anthine fish, Pseudanthias calloura, is described on the basis of three specimens from Palau. The new species differs from other congeners in having a complicated color pattern of the caudal fin and the following characters: moderately forked caudal fin; dorsal fin with 10 spines, the anterior ones being shorter than the rest, and with 16 soft rays; second anal spine shorter than the third; 19 pectoral rays; scales on lateral line 51 (holotype) to 53 (paratypes) in number; tongue without teeth; circumorbital rim with several fleshy projection on posterior part; a row of fine scales occurring asymmetrically behind alternate dorsal spines on both left and right sides; preopercle margin finely serrated; interopercle and subopercle margins smooth. Received: June 9, 1999 / Revised: September 23, 2000 / Accepted: February 23, 2001     

Chromis okamurai,a new damselfish from the Okinawa Trough,Japan

A new pomacentrid fish,Chromis okamurai, is described from a single specimen taken from the Okinawa Trough (25°53.4′N, 123°59.4′E), in 135–175 m. This species is most closely related to the deep-dwellingC. mirationis, sharing with it the same meristic data (in particular XIV dorsal spines and 2 upper and lower caudal spinules), large eye, and relatively deep body. It differs in having a small round posterior nostril (large and slit like inmirationis), longer second anal spine, shorter pelvic fins, and in color: two dark brown stripes on body and a pale pectoral-fin axil (mirationis has a single, midlateral, yellow to yellowish brown stripe which extends broadly onto lower part of caudal fin, and a black pectoral axil).     

Description ofGerres chrysops sp. nov. From Thailand and redescription ofGerres setifer (Hamilton, 1822) andG. Decacanthus (Bleeker, 1865) (perciformes: Gerreidae)

Gerres chrysops, a new gerreid species from the Gulf of Thailand, is described on the basis of 29 specimens, 58–83 mm in standard length (SL). A small-sized species (less than 100 mm SL), it is characterized by a silvery-gold sheen on the head and trunk, vivid yellow or yellowish-hyaline fins in life, two supraneural bones (formula 0/0/2/) and dorsal fin rays usually IX, 10. The new species is similar toG. decacanthus (Bleeker, 1865) andG. setifer (Hamilton, 1822), which are redescribed. being similarly small valid gerreid species characterized by two supraneural bones. Together, the three species comprise “theGerres setifer complex.”Gerres chrysops differs from bothG. decacanthus andG. setifer in life and fresh colors, the body being silvery-gold with vivid yellow or yellowish dorsal, caudal, anal and pelvic fins, and yellowish-hyaline pectoral fins (vs. silver body with hyaline fins in the latter two species).Gerres setifer differs fromG. chrysops andG. decacanthus in having the last dorsal fin spine longer than the penultimate spine (vs. almost same length or shorter), usually ten dorsal fin spines and nine soft dorsal rays (vs. usually IX, 10), and 8 or 9 lower series gill rakers (vs. usually 7).Gerres decacanthus differs fromG. chrysops andG. setifer in having a shorter head, lesser body depth at the first anal fin spine base, lesser body width at the pectoral fin base, and shorter second dorsal and third anal fin spines. The new species is currently known only from Angsilla, near Bangsaen, and around Si Chang Island, northeastern Gulf of Thailand.Gerres decacanthus inhabits southern Chinese waters andG. setifer is currently known from the Bay of Bengal to the Andaman Sea.     

Systematic revision of the formerly monotypic genus Tanganikallabes (Siluriformes: Clariidae)

The monotypic genus Tanganikallabes, endemic to Lake Tanganyika, is a poorly known member of the family Clariidae. Examination of 142 specimens housed in museum collections has revealed the presence of at least two additional species in this genus. Tanganikallabes alboperca sp. nov. is distinguished from all congeners by the length of its pelvic fins, the presence of a depigmented vertical bar on the opercular margin, and a combination of additional morphometric (pectoral spine length, preanal length, body depth at anus) and meristic (dorsal and anal fin ray counts) characters. Tanganikallabes stewarti sp. nov. is distinguished from other Tanganikallabes species by having a relatively shorter, incomplete lateral line, and shallow body depth at the anus, as well as shorter prepelvic and preanal lengths, and a longer anal fin with a higher number of fin rays. Several morphological characters, as well as genetic data from cytochrome b (mitochondrial DNA) and 18S–ITS1–5.8S–ITS2–28S (ribosomal DNA), indicate that Tanganikallabes constitutes a monophyletic group within the Clariidae and support the recognition of additional species diversity. The monophyly of Tanganikallabes, coupled with the geographical isolation of this group to a single lake satisfy the requirements for its classification as a true species flock, the latest to be described from Lake Tanganyika. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 165 , 121–142.     

Oncaea praeclara n. sp. (Copepoda: Poecilostomatoida) from deep-sea hydrothermal vents in the eastern Pacific

A new species of planktonic copepod, Oncaea praeclara, is describedfrom a depth of 2003–2635 m at the East Pacific Rise,the Galapagos Rift, and the Guaymas Basin in the Gulf of California.The species may be recognized by a combination of characters:its relatively large size; the long caudal ramus, which is abouttwo times longer than the anal segment and has a ratio of 4.96–6.7:1;the sexual dimorphism in the armature of the fourth segmentof the second antenna; and the labrum with a nearly straightposteroventral margin having four median teeth and lateral setules.     

Sexual dimorphism and developmental patterns in the external morphology of the vaquita,Phocoena sinus

A total of 56 vaquitas (Phocoena sinus) were examined to evaluate their sexual dimorphism and isometric and/or allometric growth in 35 external characteristics. Absolute and relative (to total length) measurements and growth rates were compared between sexually immature and mature females and males. T‐tests and analysis of variance (ANOVA) and covariance (ANCOVA) were used to evaluate sexual dimorphism. Sexual dimorphism in the vaquita was detected in the total length, head region (from blowhole to tip of upper jaw), anterior section of the body (from dorsal fin to tip of upper jaw), dorsal fin and the genital and anal regions. Fluke width is relatively larger in mature males than immature males, but in females this relative metric does not change during their development. In addition, males present a higher dorsal fin. These somatic changes are probably related to the swimming capacity (speed, agility, maneuvering) during the breeding season and/or foraging activities. A linear model of growth was used to determine possible proportional changes with respect to total body length through the development of 33 external characteristics. The anterior region of the body and the flippers were relatively larger in immature individuals than in mature ones.     

Description of a new species of Triplophysa (Teleostei: Nemacheilidae) from Guizhou Province,China

A new cave‐dwelling fish species Triplophysa guizhouensis is described based on specimens collected from Guizhou, China, in a subterranean system interconnected with the Hongshui River drainage. The species can be distinguished from its congeners by a combination of characters: eyes present; caudal fin with 14 branched rays; inner gill rakers of first gill arch 8–10; posterior chamber of air bladder developed; and body posterior of dorsal fin scaled. A key to species of Triplophysa in the Pearl River basin is provided.     

Two new species and a new record of the genus Sinogastromyzon (Teleostei: Balitoridae) from Yunnan, China

Two new species and a new record of Sinogastromyzon are described from Lixianjiang River of Yunnan province, China. Sinogastromyzon lixianjiangensis, new species, can be distinguished from its congeners by the following characters: pectoral fin with XIII–XIV, 15–17 rays; pelvic fin with X–XI, 10–12 rays; 60–65 lateral-line scales; no scales on the dorsum of paired fins or the region between axilla of pectoral fin and pelvic-fin origin; tip of pelvic fin close to anus; tip of anal fin close to caudal-fin base; anal-fin origin nearer to the caudal-fin base than to the posterior pelvic-fin base; anus nearer to anal-fin origin than to the posterior pelvic-fin base; dorsal side of the body with 9–11 black blotches. Sinogastromyzon macrostoma, new species can be distinguished from its congeners by the following characters: pectoral fin with XII–XIV, 12–15 rays; pelvic fin with VII–IX, 11–13 rays; 48–56 lateral-line scales; mouth extremely big, slightly arched; no scales on the dorsum of paired fins or the region between axilla of pectoral fin and pelvic-fin origin; tip of pelvic fin far beyond anus; tip of anal fin far from caudal-fin base; anal-fin origin about midway between the posterior pelvic-fin base and caudal-fin base; anus nearer to posterior pelvic-fin base than to anal-fin origin; dorsal side of the body uniformly gray, without regular blotches in formalin preserved specimen. Sinogastromyzon cf. multiocellum is firstly recorded in China.