Deeper Caudal Peduncle Research Articles

Validity of <i>Epigonus megalops</i> (Perciformes: Epigonidae), Redescription of <i>E. atherinoides</i>, and First Record of <i>E. draco</i> from the Central South Pacific

A deepwater cardinalfish, Hynnodus megalops Smith and Radcliffe in Radcliffe, 1912 , originally described from four specimens from the Philippines, is redescribed as a valid species of Epigonus. Epigonus megalops is similar to E. atherinoides ( Gilbert, 1905 ) but differs in having a relatively longer head and upper jaw, a relatively deeper caudal peduncle, and ctenoid scales on the lateral sides of the body. Epigonus atherinoides is redescribed based on the holotype, previously known specimens, and newly collected ones from the Society Islands and Western Australia. Additionally, two specimens of E. draco Okamoto, 2015 collected from the Society Islands represent the first record of this species from the central South Pacific.

Isolated charrs of the genus Salvelinus (Salmonidae) from lakes of the Uzon Caldera, Kamchatka: 1. Charr of Lake Dal’nee

Charrs of the genus Salvelinus from the ultraoligotrophic Lake Dal’nee Maar differ from anadromous Dolly Varden S. malma in larger head with elongated jaws, larger gill cover, lower body with a deep caudal peduncle and short pelvic fins displaced anteriorly, larger number of scales in the lateral line, and larger number of rays in the unpaired fins. The lacustrine charrs also differ from the maternal Dolly Varden population in longer free part of the maxilla, lower widths of the opercular bones, and narrower suspensorium. Polymorphism of mtDNA is low, and unique haplotypes of the D-loop control region are not revealed. The life span of the lacustrine charrs reaches 11 years; and their maximum length and weight are 47 cm and 820 g. The spawning is registered in the fall at the slope of the bottom near the mouth of the single stream flowing into the lake. The abundance of the spawning group slightly exceeds 1000 individuals. This group is recruited from offspring migrating during their early life to the stream with limited food resources, and more numerous progeny remaining in the lake do not reach sexual maturity. The main food sources of adult charrs during summer are planktonic crustaceans, imago of insects, and own juveniles.

A New Species ofArapaima(Osteoglossomorpha: Osteoglossidae) from the Solimões River, Amazonas State, Brazil

A new species of Arapaima has been discovered from the central Amazon of Brazil. This new taxon is readily distinguished from all other Arapaima by the following three characters: 1) dorsalmost lateralis sensory cavity on preopercle extremely slender (vs. broadly oval or nearly rectangular in other nominal taxa); 2) ventrolateral margin of head where third infraorbital meets anterior limb of preopercle strongly angled such that ventral surface of head is almost flat (vs. ventrolateral margin of head relatively rounded); and 3) anterior third of dorsal-fin base covered with an enlarged, thickened sheath that hides anterior dorsal-fin rays when adpressed (vs. no thickened sheath on anterior base of dorsal fin and anterior dorsal-fin rays visible when adpressed). Distinguished from all other Arapaima except A. agassizii by having extremely long fourth infraorbital. Distinguished from A. arapaima and all other examined non-type specimens by notably slender body (the holotypes of A. gigas, A. mapae, and A. agassizii also have slender bodies). Further distinguished from A. mapae and A. agassizii by having relatively deep caudal peduncle (6.0% SL, vs. ∼4.0% in latter two taxa), and from A. gigas by having dentary teeth in a single row (vs. dentary teeth in 2–2.5 irregular rows). This species was collected near the confluence of the Solimões and Purus rivers in Amazonas State, Brazil. It is the first new species of Arapaima to be described since 1847, and comparisons with Arapaima from Mamirauá Reserve demonstrate that there are at least two species of Arapaima present in Amazonas State.

Recent parallel divergence in body shape and diet source of alewife life history forms

Recent work suggests that juvenile alewives (Alosa pseudoharengus) share similar phenotypes among independently derived landlocked (freshwater resident) populations. Based on this observation, it is possible that the alewife life history forms represent a case of parallel adaptive divergence. To further evaluate this hypothesis, we describe patterns of body shape divergence between anadromous and landlocked alewife life history forms using geometric morphometrics. Our results suggest that body shape differs significantly between juveniles of the alewife forms: anadromous fish were more robust, with larger heads and deeper caudal peduncles, while landlocked fish from three independently isolated populations were more fusiform with thinner caudal peduncles and smaller heads. These differences matched population level dietary patterns, which suggest that anadromous fish consumed more littoral resources than landlocked fish. Finding consistent differences across populations of the same form supports the notion that landlocked alewives have diverged from their anadromous ancestors in a parallel manner, in response to pressures associated with being isolated in freshwater lakes. Comparing alewife phenotypes to expectations from the literature suggests that neither migration distance of the population, nor the relative availability of habitats in each lake, are likely drivers of the pattern we report. Instead, the pattern is consistent with the hypothesis that divergence between alewife forms results from the distinct effects of each form on its zooplankton prey.

Domestication shapes morphology in rainbow trout Oncorhynchus mykiss

In this study, clonal lines from North American resident and migratory populations of rainbow trout Oncorhynchus mykiss adapted to different geographical conditions and with different domestication histories were characterized morphologically. Lines reared in a common-garden experiment were characterized for external shape and meristic values, searching for a general pattern of morphological variation due to exposure to captive conditions. A sharp distinction was identified between wild and captive lines. The body profile was deeper in captive lines, with longer dorsal and anal fins and shorter and deeper caudal peduncles. Highly significant differences were also identified in meristic values among the lines but no consistent relation between meristic values and domestication status was detected. This morphological characterization will facilitate the selection of lines with divergent phenotypes for subsequent quantitative trait loci analysis, aimed at identifying genome regions linked with morphological adaptive response to captive conditions.

Balitora laticauda, a new species of stone loach (Teleostei: Cypriniformes: Balitoridae) from Krishna River, northern Western Ghats, India

A new species of stone loach Balitora laticauda is described from the Krishna River, northern Western Ghats, India. It differs from all known species of the genus in a combination of characters including: 10 transverse bands on the dorsal surface, deeper caudal peduncle, two prominent rows of papilla encircling upper lip where the proximate row has small papillae while distal row has larger papillae, 66-68 lateral line scales, 8-9 simple rays in pectoral fin, two simple rays in the pelvic fin and pectoral fin not surpassing pelvic fin base. The new species also differs from its related species in the ratios such as caudal peduncle length to depth (2.21-2.89), standard length to body depth (7.48-8.72), head length to head depth (2.11-2.50), head length to interorbital distance (2.20-2.96), head depth to head length (0.42-0.47), eye diameter to head length (0.13-0.17) and head width to gape of mouth (3.12-4.78). As percent of standard length B. laticauda sp. nov. differs from other related species with respect to caudal peduncle depth (6.3-7.4%), caudal peduncle length (15.0-20.0%), body width at anus (8.7-11.5%), body depth at anus (9.1-11.4%), pre-dorsal fin length (43.7-47.4%), pre-pectoral fin length (12.9-16.2%), pre-anal fin length (74.3-79.3%), pre-pelvic fin length (44.4-48.3%), pelvic fin length (19.3-23.7%), pectoral fin length (24.1-28.9%) and body depth at dorsal (11.5-13.4%).

Rainbow trout (Oncorhynchus mykiss, Walbaum ) develop a more robust body shape under organic rearing

Prolonged exposure to captive conditions has led to the development of a rainbow trout ‘farmed’ pheno- type, which is different from that of wild trout. Selec- tion for desirable productive traits in hatcheries has resulted in the development of some morphological traits that are maladaptive in nature. The recent development of organic aquaculture, guided by the well-being of the fish, could potentially produce a new farmed phenotype that would be more adaptive in nature. In this study, rainbow trout reared in intensive and organic farms were compared by means of shape analysis, to detect patterns of shape variation associated with rearing environment. The results of this study highlight a significant effect of the rearing method on rainbow trout shape: organi- cally reared trout showed a higher body profile, in particular in the head and trunk regions, shorter median fins and a deeper caudal peduncle. A combined effect of density and habitat complexity could have contributed to the observed shape differences: in organic rearing systems, lower densi- ties and steady water could increase territoriality and aggressive interactions, promoting body designs more functional in rapid attacks and escapes.

Krobia xinguensis, a new species of cichlid fish from the Xingu River drainage in Brazil (Teleostei: Cichlidae)

Krobia xinguensis is described from localities in the headwaters and in the lower part of the rio Xingu. It is distinguishedfrom the other two species in the genus, K. guianensis and K. itanyi, primarily by deeper caudal peduncle, and details ofthe colour pattern, including contrasting interorbital stripes and a small dark spot anteriorly on each side of the lower jaw.Krobia xinguensis represents a considerable range extension of the genus from the Guianas and northern tributaries of the lower Amazon, into a major south bank Amazon tributary.

Mechanisms of food partitioning and ecomorphological correlates in ten fish species from a tropical estuarine marine protected area (Bamboung, Senegal, West Africa)

Ecomorphological correlates were sought among 10 fish species of different life history traits in a tropical estuary. Results from gut contents analysis showed that fish species were classified into four trophic groups including detritivores, zooplanktivores, benthivores, piscivores and macrocarnivores. Resource partitioning among fishes was under the influence of their morphological attributes. Detritivores and zooplanktivores were both characterized by the possession of long gill raker and a wide mouth. The suction feeding mode has been hypothesized to explain the morphological convergence. Detritivorores have additionally a long digestive tract, long pectoral and dorsal fins, a short caudal fin, while zooplanktivores have otherwise big eyes. Benthic invertebrate feeders had big eyes, long dorsal fins, a long head prolonged by protrusive jaws. Piscivores and macrocarnivores were both characterized by the possession of a deep caudal peduncle, up-positioned eyes and a wide and deep mouth. However, the mouth size was more pronounced in strict piscivores, while macrocrustacean feeders had a longer head and long pectoral and dorsal fins. This study corroborates the consistency of the relationships between morphology and ecology in fish assemblages of tropical estuarine systems. Whatever the prey functional type, benthic foraging fishes were characterized by the possession of long paired fins. Key words: Diet, morphology, resource partitioning, life history traits.

Australoheros perdi, new species (Teleostei: Labroidei: Cichlidae) from the lacustrine region of the Doce River Valley, southeastern Brazil, with biological information

Australoheros perdi is a new species herein described from the lacustrine region of the middle Doce River basin, Doce River Valley, southeastern Brazil. The new species is distinguished from all its congeners by having only 25 vertebrae and by a combination of characters states listed below: three abdominal bars in all stages of life, a conspicuous, rounded caudalfin base spot, a conspicuous wide longitudinal stripe, head with depression in the region above the eyes, tip of pelvic fin reaching vertical through third to sixth anal fin spine base, fewer dorsal-fin spines, fewer pectoral-fin rays, fewer caudal vertebrae, fewer proximal radials on dorsal-fin base, more proximal radials on anal-fin base, more pleural ribs, a longer caudal peduncle, a deeper caudal peduncle, a wide ectopterygoid, a longer last anal-fin spine and a longer lower jaw. The available phylogenetic tree of the genus does not include the species from southeastern Brazil, thus impeding any discussion of the phylogeny of these species.

Glyptothorax dikrongensis, a new species of catfish (Teleostei: Sisoridae) from Arunachal Pradesh, northeastern India

Glyptothorax dikrongensis, a new species of sisorid catfish from the Dikrong River in northeastern India, is described. Glyptothorax dikrongensis can be differentiated from all congeners, except G. indicus, G. rugimentum and G. obliquimaculatus, by the presence of an unculiferous patch on the posterior region of the lower lip, in between the inner mandibular-barbel bases, and unculiferous striae of the thoracic adhesive apparatus extending anteriorly onto the gular region. Glyptothorax dikrongensis is distinguished from G. indicus by the following combination of characters: equal distance between the posterior end of the pectoral-fin base and the pelvic-fin origin and between the pelvic-fin and the anal-fin origin (vs. distance between posterior end of pectoral-fin base and pelvic-fin origin greater than between pelvic-fin origin and anal-fin origin), and the pelvic-fin origin anterior to or almost at a vertical through the posterior end of the dorsal-fin base (vs. posterior to the dorsal-fin base). Glyptothorax dikrongensis is distinguished from G. rugimentum in lacking vertical bars on the body and caudal peduncle, and having a deeper caudal peduncle (8.4–9.2 vs. 6.1–7.6% SL) and a shorter dorsal-fin spine (10.1–11.1 vs. 15.2–18.6% SL). It is distinguished from G. obliquimaculatus in lacking dark, oblique blotches on the body, and in having a shorter dorsal-fin spine (10.1–11.1 vs. 13.4–16.4% SL).

A new species of Microglanis (Siluriformes, Pseudopimelodidae) from lower Rio Tocantins basin, Pará, Brazil, with description of superficial neuromasts and pores of lateral line system

Microglanis robustus, new species, is the first Microglanis to be described from the Rio Tocantins basin, Pará, Brazil, and differs from the congeners by the presence of a cordiform blotch in the nape, instead of a transverse light stripe; neuromasts of the superficial lines surrounded by melanophores; robust body with short snout, head and predorsal distance; and deep caudal peduncle. The mapping of superficial neuromasts and cephalic sensory canals evidenced intra and interespecific polymorphisms and, therefore, of little value for phylogenetic analysis within the genus.

Description of two new species of Nannocharax Günther, 1867 (Teleostei: Characiformes: Distichodontidae) from the Cross River, Cameroon

Two new species of the African characiform genus Nannocharax Günther, 1867 are described from the Cross River in Cameroon. Nannocharax zebra sp. nov. is distinguished from all other described Nannocharax species except N. schoutedeni Poll, 1939, N. latifasciatus Coenen & Teugels, 1989, N. ansorgii Boulenger, 1911 and N. procatopus Boulenger, 1920 by a shorter distance between the posterior border of the anus and the articulation of the first anal-fin ray (2.2–3.7 vs. 4.2–14.2% of SL). It differs from N. schoutedeni by having 39–43 vs. 36 or 37 lateral line scales, from N. latifasciatus by a deeper caudal peduncle (55.9–63.8% vs. 48.1–50.8% of SL), from N. ansorgii by having 12 or 13 rather than 9 anal-fin rays, and from N. procatopus by having a shorter caudal peduncle (11.3–15.2% vs. 18.0% of SL), and by having 39–43 rather than 36 lateral line scales. Nannocharax usongo sp. nov. is distinguished from all other Nannocharax species mainly in the distance from the border of anus to the articulation of first anal-fin ray (0.9–1.8 vs. 2.2–14.2% of SL) and by its body coloration consisting of 7–11 dark blotches along the lateral line often coalesced to one wide black band, and 7–12 small saddle-blotches along the dorsum.

New fossil fish Musculopedunculus micklichi (Trichiuroidei) from the lower Oligocene of Germany

The new fossil fish Musculopedunculus micklichi (type locality: the lower Oligocene slate sediments to the south of Heidelberg, FRG) is described from an incomplete skeleton impression. The diagnostic characters are the powerful and relatively deep caudal peduncle with the hemal and, probably, neural processes of anterior preural centra strongly enlarged, located at an angle of about 60°, as well as a compressed body, high number of vertebrae (probably, about 80), the dorsal fin probably slightly differentiated into the spiny and soft parts, and a well-developed fronto-occipital sagittal crest. On the basis of these and other features, the fossil taxon does not conform to the known Euzaphlegidae, Gempylidae, and Trichiuridae and is recognized as the new family Musculopedunculidae probably belonging to the Trichiuroidae.

Two new catfish species of the genus Pseudecheneis Blyth (Teleostei: Siluriformes) from northeastern India

Two new catfish species of the genus Pseudecheneis, viz., P. ukhrulensis sp. nov. and P. sirenica sp. nov. are described from northeastern India, from streams of Ukhrul district, Manipur (Chindwin basin) and Siren River, Upper Siang District, Arunachal Pradesh (Brahmaputra basin), respectively. The two species can be distinguished from their closest congener P. sulcata in having prominent bony spurs on the anterodorsal surface of the first dorsal-fin pterygiophore (vs. absent), from P. crassicauda in shallower caudal peduncle, from P. serracula in shorter adipose fin base and from P. stenura in deeper caudal peduncle. P. sirenica sp. nov. is distinguished from P. eddsi in its longer pelvic fin and anal fin and from P. ukhrulensis sp. nov. in having longer pectoral fin and caudal peduncle. A key to identification of Pseudocheneis of India and Nepal is given.

A new sisorid catfish of the Genus Exostoma Blyth from Manipur, India

Manuscript 1546; © ZOO; Date of publication 21 December 2006 Received 01 April 2006; Revised received 13 November 2006 Finally accepted 08 December 2006 W See Images in the web supplement at www.zoosprint.org ABSTRACT A new sisorid catfish, Exostoma barakensis is described from the Iyei River (Barak drainage) of Manipur, India. It is distinguished from E. berdmorei in having deeper body, its depth 15.6 (14.0-16.5) vs. 10.9 % SL; less numbers of anal fin rays ii, 41⁄2 -5 vs. i, 6; broadly rounded vs. pointed snout; emarginated vs. deeply forked caudal fin. It differs from E. labiatum in having deeper caudal peduncle, its height 49.8 (44.1-56.7) vs. 31.2-38.7 % caudal peduncle length; interdorsal space present vs. absent; less number of pectoral fin rays i, 10-11 vs. i, 12-13; caudal emarginated vs. forked. It differs from E. vinciguerrae in having wider head, its width 88.9 (85.2-91.6) vs.105.1 (105-108) % HL; smaller eye, its diameter 9.6 (7.3-11.6) vs.16.2 (16.0-16.4) % HL. It also differs from E. stuarti in having shallower body, its depth 15.8 (14.2-16.9) vs. 18.1 % SL; longer snout, its length 59.5 (58.1-61.5) vs. 47.6 % HL; larger eye, its diameter 9.6 (7.311.6) vs. 4.7 % HL; deeper caudal peduncle, its height 49.8 (44.1-56.7) vs. 42.8 % caudal peduncle length. Exostoma vinciguerrae and E. stuarti that synonymised under E. labiatum have been examined and found to have distinguishable differences from E. labiatum, and therefore have been resurrected as valid species.

Juvenile morphology and occurrence patterns of three Butis species (Gobioidei: Eleotridae) in a mangrove estuary, southern Thailand

Juveniles of three eleotrid Butis species (B. butis, B. humeralis, and B. koilomatodon) are described; their occurrence patterns were examined in Sikao Creek, a mangrove estuary located in southern Thailand. Juveniles of each species were distinguished by the following characters: B. butis with no bands on body and pale pelvic fins; B. humeralis with no bands on body and densely pigmented pelvic fins; and B. koilomatodon with 5–6 regular bands on body and a fleshy process (preorbital knob) on the snout. Although B. butis shared the aforementioned characters with B. amboinensis found in the same estuary, the former was distinguished from the latter by having a greater number of pectoral fin rays (18–21 vs. 17) and a deeper caudal peduncle. Distribution patterns of the three Butis species in Sikao Creek were distinguishable from each other. Smaller B. butis [mean ± SD = 22.7 ± 16.9 mm in standard length (SL), n = 32] occurred in the upper reach of the estuary, while larger specimens (52.4 ± 26.2 mm SL, n = 18 and 51.5 ± 29.7 mm SL, n = 10, respectively) were found in the middle and lower reaches and none in the marine area. In B. humeralis and B. koilomatodon, only juveniles were caught except for one adult specimen each. Juveniles (8.9–16.5 mm SL, n = 79) of B. humeralis occurred in the upper and middle reaches and the marine area. B. koilomatodon juveniles (9.9–13.7 mm SL, n = 30) were distributed in all areas from the lower to upper reaches.

The origins of ecotypic variation of rainbow trout: a test of environmental vs. genetically based differences in morphology

Although morphological plasticity has been observed in a variety of taxa, few experimental studies have compared the relative proportion of morphological variability that is accounted for by environmentally induced plasticity, and how much is because of genetically based differences among populations. We compared the morphology of six rainbow trout (Oncorhynchus mykiss) populations from different ecotypic categories that were raised under flowing vs. standing-water conditions. Our data indicate that both environmental conditions and ecotypic differences account for a significant proportion of variation in morphology. Among ecotype effects, however, accounted for a much larger proportion of morphological variability than environmental conditions. Rainbow trout from stream populations had deeper caudal peduncles, and longer fins than lake populations, and rainbow trout from a piscivorous population had larger mouth and head lengths than all other ecotypes. Environmentally induced differences in morphology were primarily related to differences in mouth and head lengths, as well as fin length. Relative to morphometric differences from natural rainbow trout populations, most characteristics deviated in the same direction in our experimental populations. Our data indicate that morphological differences across rainbow trout populations have a genetic basis and may represent locally adaptive characteristics and highlight the role of ecology in promoting phenotypic divergence.

Parallel evolution of the sexes? Effects of predation and habitat features on the size and shape of wild guppies

Environmental gradients often lead to the parallel evolution of populations and species. To what extent do such gradients also lead to parallel evolution of the sexes? We used guppies (Poecilia reticulata) to examine the parallel and independent (sex-specific) aspects of population divergence in response to predation and habitat features. Geometric morphometrics was used to analyse size and shape variation for 1335 guppies from 27 to 31 sites sampled in each of 2 years. Body size showed strong parallel population divergence; both sexes were larger at sites with a more open canopy and with higher flow. Body shape showed a mixture of parallel and independent population divergence. The strongest and most consistent effects were (1) high-predation sites had males with smaller heads and deeper caudal peduncles, (2) open-canopy sites had females with smaller heads and more distended abdomens and (3) high-flow sites had males and females with smaller heads and deeper caudal peduncles.

Ecomorphology and habitat utilization of Cottus species

We investigated relationships between morphological attributes and mesohabitat use in populations of Cottus carolinae. Field studies revealed significant differences between Ozark and prairie stream mesohabitats where populations of C. carolinae occurred. Features of the mesohabitat that were characteristic of each stream type correlated with intra- and inter-specific differences in morphological attributes of Cottus. The morphology of Cottus occurring in the deeper, slower, and siltier prairie stream exhibited larger head width and depth, body width and depth, and caudal peduncle width while those occurring in a shallower, faster flowing Ozark stream had longer pelvic fins, larger eyes, and deeper caudal peduncles. Each population had a morphology tailored to optimize its performance in a specific habitat. Results of laboratory based performance studies using a variable flow chamber revealed that critical current velocities (CCV) of live and preserved specimens were weakly associated with distinct combinations of morphological traits. Specimens with higher CCV measurements typically had longer pelvic fins, larger eyes, and deeper caudal fins (Ozark morphology). Those with lower CCVs had larger head width and depth, body width and depth, and caudal peduncle width (prairie morphology) in studies using cobble as the substrate. Differences in flow regimes between prairie and Ozark streams may generate specific niches for specific morphotypes, and current velocity may exert selective pressure on morphology.