Morphological differences among three color morphotypes of Sebastes inermis (Scorpaenidae)

 Morphological differences among three color morphotypes occurring almost sympatrically (A, reddish type; B, blackish type; C, brownish type) of Sebastes inermis are clarified. Twenty-six morphometric characters and seven meristic characters were examined on about 20 specimens of each morphotype, 15 of the morphometric characters differing significantly. Principal component analysis (PCA) of the morphometric characters showed morphotype C to differ from the other two morphotypes. Canonical discriminant analysis (CDA) of the morphometric characters showed clear separation of each morphotype. Four meristic characters also differed significantly. Modes of pectoral fin ray counts of morphotypes A, B, and C were 15, 16, and 17, respectively, and the modes of anal fin ray counts of morphotypes B and C were 7 and 8, respectively. Many individuals of morphotype A had seven or eight anal fin rays. These differences suggested that the three morphotypes may be reproductively isolated from each other. Received: October 15, 2001 / Revised: March 14, 2002 / Accepted: April 9, 2002     

Morphological variations among four riverine populations (Bangladesh) of endangered catfish Rita rita (Hamilton, 1822)

The morphological variation of the endangered catfish Rita rita was studied based on meristic, length–weight relationship (LWR), traditional (TRA) and truss (TRU) distance based morphometric analysis of 200 juveniles collected from the Old Brahmaputra, Jamuna, Meghna and Kangsa rivers. Data were subjected to Kruskal–Wallis test for meristic counts, t test for LWR, univariate ANOVA, multivariate discriminant function analysis and canonical analysis (CA) both for TRA and TRU morphometric characters to discriminate the populations. Kruskal–Wallis test denoted that only one (caudal fin rays) out of six meristic counts was significantly (p < .05) variable among the stocks. One sample t test clarified that all parameters of LWR were significantly (p < .05) differentiated in all stocks. Univariate ANOVA revealed significant (p < .001, p < .01, and p < .05) differences among the four stocks in 14 of 15 standardized TRA traits and 17 of 25 TRU distances, respectively. The first discriminant function (DF1) explained 59.4% and 68.0% of total variance, while 30.6% and 23.1% by DF2, 10.0% and 8.9% by DF3 for TRA and TRU features, respectively among the stocks. CA showed a clear separation of the stocks both for TRA and TRU measurements. The overall random assignment of individuals into their original groups was high as 78.5% for TRA and 78.0% for TRU characters, respectively, indicating that all the four stocks are highly divergent from each other. The results exposed existence of four distinct phenotypic stocks of R. rita in the tested rivers.     

Morphological variation of the pikeperch Sander lucioperca (L.) in the southern Caspian Sea, using a truss system

A morphometric truss network system and meristic counts were used to investigate the hypothesis of population fragmentation of pikeperch Sander lucioperca among four major fishing areas in the Caspian Sea drainage. Univariate analysis of variance showed significant differences between the means of the four groups for 20 out of 32 standardized morphometric measurements (27 truss, five traditional characters) and six out of nine meristic counts. The first two canonical discriminant functions accounted for 93 and 92.3% of the total variability in morphometric and meristic characteristics, respectively. A dendogram derived from cluster analysis of Mahalanobis distances and a discriminant analysis among the groups confirmed three distinct populations in these regions, while there was a relatively high degree of overlap between all locations when using meristic characters. The most relevant morphometric characteristics were the measured distances on body heights and the caudal peduncle area. This study indicated that the morphometric truss network system was more adequate than meristic characters for separation among the populations.     

Short-term toxicity of oil-based drilling fluid to the brackish-water shrimp Palaemonetes africanus

Thirty-nine morphometric and five meristic comparisons were carried out on 12-month-old interspecific and intergeneric hybrids of the African clariid catfishes Heterobranchus longifilis, Clarias gariepinus and Clarias anguillaris from experimental earthen ponds in Nigeria. Canonical discriminant analysis accounted for 89.4% of the variations, with eigenvalues of 151.69 and 9.06, respectively, the highest loading in the two axes coming from only 12 variables. A re-analysis based on those 12 variables revealed four major groups among the nine genetic combinations from a plot of axes 1 and 2, which accounted for 95.2% of the variations. The Mahalanobis square distance (D ²) between the offspring of the various mating combinations also revealed the varying levels of relationship between them based on their morphometric and meristic characters. The interspecific hybrids showed some level of heterosis only in the inheritance of the length of the frontal fontanelles compared to that of the putative Clarias species. The study shows the level of similarities in many of the morphometric and merisitic features, especially among the hybrids, and the distinguishing features that can be used to identify the hybrids from their putative parents.     

Stock differentiation of the greater lizardfish Saurida tumbil (Teleostei: Synodontidae) collected along the western coast of the Arabian Gulf and Sea of Oman using meristic characters

Meristic variation among stocks of greater lizardfish Saurida tumbil through the western coasts of the Arabian Gulf and Sea of Oman was examined using meristic characters. Statistical analysis of meristic traits proposed that there is constrained migration of populations of greater lizardfish along the western coast of the Arabian Gulf and Sea of Oman. Overlapping of the two samples from the northern part of the Arabian Gulf (Iraq-Kuwait waters), three samples from the middle region of the Arabian Gulf (Bahrain-Qatar-Saudi Arabia) and two samples from the southern part of the Arabian Gulf/Sea of Oman (United Arab Emirates–Sultanate of Oman) suggested that there are three self-recruiting populations in the studied area. Inspection of the role of each meristic trait variable to Canonical discriminant analysis showed that changes among samples appeared to be linked with the pattern of distribution of water temperature and configuration of current in both the Arabian Gulf and Sea of Oman areas.     

Molecular and morphological differences between two geographic populations of Salanx ariakensis (Salangidae) from Korea and Japan

Geographic variations of a salangid, Salanx ariakensis, from Korea and Japan, based on partial mtDNA cyt b gene sequences and morphometric data, are presented and compared with Salanx cuvieri from China. Analyses of molecular variance (AMOVA) suggested that the two populations of S. ariakensis differed significantly from each other in pairwise fixation index (F _ST = 0.43), although their reciprocal monophyly was not constructed in the phylogenetic analysis. The phylogenetic analysis, however, supported the reciprocal monophyly of S. ariakensis (Korean population + Japanese population) and S. cuvieri. Differences in genetic structure between the two populations of S. ariakensis were suggested by diversity indices, mismatch distribution shape, and minimum spanning network. In particular, diversity indices indicated that the Korean population was historically larger and more stable than the Japanese population. In addition, both the principal component analysis (PCA) and canonical discriminant analysis (CDA) for morphometric characters, and the Kruskal–Wallis test for some meristic characters, showed that the two populations of S. ariakensis differed from each other, although morphological differences between the two populations of S. ariakensis were smaller than those between S. ariakensis and S. cuvieri. Such morphological differences were consistent with the differences in mtDNA.     

Comparative morphology of pre‐extrusion larvae,Sebastes mentella and Sebastes norvegicus (Pisces: Sebastidae) in Icelandic waters

This study evaluated potential differences in morphology of unextruded larvae from Sebastes mentella and Sebastes norvegicus in Icelandic waters. Fifty‐four larvae of each species were measured, and 18 measurements were recorded for each specimen (morphometric, meristic and pigmentation patterns). Pre‐extrusion larvae of S. norvegicus were longer than those of S. mentella. Additionally, there were significant differences in morphometric, meristic and pigmentation characters between pre‐extrusion larvae of these species. Pigmentation of S. mentella differed from that of S. norvegicus in several aspects. Dorsal and ventral body pigmentation tended to begin more posteriorly in S. mentella, therefore, the overall length of these pigmented areas tended to be longer in S. norvegicus.     

Use of shape analysis in the investigation of disputable meristic characters for Ameiurus melas (Rafinesque, 1820) and Ameiurus nebulosus (Lesueur, 1819)

The aim of this paper was to use geometric morphometry as a helpful tool to clarify the overlap between meristic characters (such as the number of anal fin rays) of different fish identification keys employed for the two sister species, Ameiurus melas and Ameiurus nebulosus. Geometric morphometry included shape analysis of 15 landmarks on 432 specimens. The analyses showed significant differences among groups based on the sampling site, while there was no difference among groups based on the number of anal fin rays (used to distinguish species). This suggests that the use of meristic characters for the determination of these two sister species is rather questionable.     

Identification and discrimination of Electrogena species by numerical methods (Ephemeroptera: Heptageniidae)

Abstract. Nine species of Electrogena from thirty-one populations were investigated on the basis of five meristic and five ratio characters of the larvae. The attribution of populations to species was checked by a cluster analysis based on the generalized distances between pairs. Groups representing species were then subjected to a multiple discriminant analysis; discriminant functions and loadings were calculated. The correct attribution of individuals to species by the discriminant functions ranged from 97% to 100%. The analysis of discriminant loadings shows which characters contribute more to the discrimination of species. Although many species could be identified with some confidence by a sequential monothetic key based on meristic and qualitative characters, the discriminant analysis improves the effectiveness of identification of all species.     

Three sympatric forms of Arctic charr Salvelinus alpinus complex (Salmoniformes,Salmonidae) from Lake Kamkanda,Northern Transbaikalia

We studied morphology, size and age structure, growth, feeding, and variation at microsatellite loci of three forms of Arctic charr Salvelinus alpinus complex (dwarf, small, large) from mountain Lake Kamkanda in River Olekma basin, northern Transbaikalia. The forms differ in meristic and morphometric characters, external appearance and size. The small form distinctly differs from the dwarf and large forms in higher number and length of gill rakers. The forms differ in growth rate; however, differences in growth between the dwarf and the small forms are not as large as between sympatric dwarf and small charr from other Transbaikalian lakes. The large form is heterogeneous in growth rate. The small form matures one year earlier than the dwarf form and has a shorter life span. The dwarf form is a benthophage, the small form is a planktophage, and the large form is a predator. The dwarf form spawns in September, while the small form spawns in November-December, and there is no overlap in their spawning time. The three forms have clear genetic differences, which support their reproductive isolation. It is assumed that the three forms of Arctic charr originated within Lake Kamkanda on the basis of trophic polymorphism and spawning time displacement and attained a high degree of morphological and genetic divergence.     

Geographic variation of Gloydius halys caucasicus (Serpentes: Viperidae) in Iran

We compared the morphological characters of populations of the Caucasian Pit Viper, Gloydius halys caucasicus, from different regions of the Alborz mountain range. For this purpose, we studied 7 metric and 21 meristic characters in 12 specimens from the western Alborz, 44 specimens from the eastern Alborz and nine specimens from the central Alborz Mountains. The results of the statistical analyses by npMANOVA, ANOVA and Kruskal Wallis tests showed significant differences between all three populations, while the western Alborz and the eastern Alborz populations are more distinct from each other. The important characters showing differences between them are: Subcaudals, dorsal scales in anterior part, dorsal scales in posterior part, supralabial scales, scales between gulars, gulars, ventrals, ratio of snout length over snout width, and ratio of snout length over head length.     

Systematic studies on Ilisha kampeni (Weber & De Beaufort, 1913) (Pisces,Clupeidae) and a biometric comparison of stocks from two localities

Ilisha kampeni (Pisces Clupeidae) is described based on new material from Bombay and Kakinada. The species was originally described as Pellona kampeni from Java and Borneo. Samples of I. kampeni from Bombay (west coast) and Kakinada (east coast) are compared, using t test and Chi-square test for meristic characters and multivariate analysis for body measurements. Significant differences observed in 6 of the 12 meristic characters and all the 6 body measurements indicate that the samples from Bombay and Kakinada belong to different stocks.     

Morphometric and meristic spatial differences and mixed groups of the whitemouth croaker (Micropogonias furnieri (Demearest, 1823)) during the spawning season: implications for management

The aim of this work was to compare the morphometric and meristic characteristics of whitemouth croaker, Micropogonias furnieri, from two different areas: the Río de la Plata (to the west) and the oceanic coast (to the east) during the summer spawning season (December 1999), and to determine whether they constitute one demographic unit or independent management groups. Data from 966 whitemouth croakers were analysed for stock discrimination between areas. The results provided further evidence that the two cohorts differ significantly in these areas. However, an important misclassification of individuals was found. The morphometric variables that contributed more to discriminate the groups were mouth length, head length, horizontal eye diameter and length of the pectoral fin. Misclassified individuals from the western and eastern groups have shown that whitemouth croaker do not display high fidelity to their known spawning grounds. The well‐classified and misclassified individuals for the western and eastern groups were found to be mature and in spawning condition, representing between 82–84%, and 66–88%, respectively. These results support the hypothesis of contemporary gene flow between the Río de la Plata and coastal Atlantic populations. Despite the misclassified individuals, morphometrics presented in this study and genetic information originating from other studies show differences between Río de la Plata and oceanic groups, and predict the two‐stock hypothesis. Problems related arising from these mixed population groups and potential implications for managements are discussed.     

Citharichthys gnathus, a new species of paralichthyid flounder (Teleostei: Pleuronectiformes) from the Galapagos Islands, eastern pacific Ocean

A new paralichthyid flounder,Citharichthys gnathus, is described from 25 specimens from the Galapagos Islands. The new species strongly resemblesC. fragilis Gilbert, distributed in the Gulf of California and adjacent waters, in general appearance, and meristic and morphometric characters, but is distinguished from the latter by two adult characters, a remarkable bony knob at the anterior tip of the lower jaw and larger proportion of snout length in standard length.     

Allometric variation and sexual dimorphism in <Emphasis Type="Italic">Lycodes yamatoi</Emphasis> Toyoshima, 1985 (Perciformes: Zoarcidae) from the Sea of Japan

A detailed analysis of allometric variation and sexual dimorphism in Lycodes yamatoi (Perciformes: Zoarcidae) was carried out using an original method developed by the authors. An allometric pattern of growth was revealed not only in plastic but in some meristic characters, such as the number of teeth on the bones of the mouthparts and the number of gill rakers on the first gill arc. It was determined that most of the morphological characters of L. yamatoi were subjected to positive allometric variability (the proportions of the head and the anterior part of the body), while growth of the remaining characters was specified by negative allometry (the length of the rays of pair and caudal fins, interorbital distance, and isthmus width) and isometry (the standard length, ante-anal distance, and head width on the vertical neck). The juveniles of L. yamatoi have no significant sexual distinctions either in plastic or in meristic characters. Adult females and males of L. yamatoi significantly differed by characters composing the head complex, the actual length of the head, and correlatively related with it ante-dorsal and ante-pectoral distances. The dimensional indexes of antedorsal and ante-pectoral distances, and the relative sizes of maxillary bones (lmx/c) are of the greatest diagnostic value for sex differentiation.     

Morphological variability of potato cyst nematodes (Globodera spp.) in the Canary Islands

Thirty populations of potato cyst nematode (Globodera spp.) from the Island of Tenerife and two populations from the UK were assessed for several morphometric and non-morphometric characters thought to discriminate between the species G. rostochiensis and G. pallida. Also 200 cysts from each population were analysed by isoelectric focusing of soluble proteins. Correlation analysis, analysis of variance and principal component analysis were used to investigate relationships between the morphometric characters, how the relationships varied between species and between populations, and which characters were most useful for discriminating between species. The two species differed significantly for each of the four morphometric characters: stylet length, fenestra length, anus-fenestra distance and the number of ridges. The stylet length and fenestra length also showed differences between populations of G. rostochiensis while stylet length and number of ridges showed differences between populations of C. pallida. In general, populations of G. pallida showed greater variation than populations of C. rostochiensis. Principal component analysis of the population means indicated that over 73% of the variation in the characters could be explained by the contrast of stylet and fenestra lengths against the anus-fenestra distance and number of ridges. A plot of the first two principal components separated the two species. Stepwise discriminant analysis provided a linear combination of these four variables which discriminated between the species. Stylet length was found to be the most useful characteristic for distinguishing the species whilst anus-fenestra distance was the least useful.     

A numerical taxonomic study of thePolygonum aviculare complex (Polygonaceae) in Belgium

16 morphological characters were assessed in 300 plants sampled from 27 populations ofPolygonum aviculare sensu lato representative of the whole ecological range of the species in Belgium. The three multivariate treatments performed, namely principal component analysis, cluster analysis and discriminant analysis provide evidence thatP. aviculare can be divided in 4 units, roughly corresponding to the four taxa recognized byChrtek. However, the results point out that subsp.monspeliense and subsp.calcatum should be included at the varietal rank within respectively subsp.aviculare (=P. heterophyllum) and subsp.aequale (=P. arenastrum) as defined byLindman. Fruit dimensions, fruit shape and tepal length are the most discriminant characters for separating the four taxa, while several other characters are discriminant at the population level only. The evolutionary significance of the variation pattern of the whole complex is discussed in terms of life history differentiation and ecological specialization.     

Lessons from a complex biogeographical scenario: morphological characters match mitochondrial lineages within Iberian Coronella austriaca (Reptilia: Colubridae)

Molecular evidence suggests that climatic fluctuations in the peninsulas of southern European during the Miocene and Pleistocene resulted in considerable genetic differentiation of organisms, probably following a ‘refugia within refugia’ model. We examined morphometric and meristic characters in museum specimens from the three Iberian clades of the smooth snake Coronella austriaca, previously described by molecular markers. We found sexual and interclade differences in scale counts and head shape. Sexes were dimorphic in the number of ventral and subcaudal scales, although sexual disparities in scale counts differed among clades. Moreover, discriminant and canonical analyses showed higher interclade differences in males than in females. The results obtained in the present study match those from molecular markers and confirm the population structure identified within Iberian C. austriaca. The observed sex discrepancy in this pattern suggests that males and females are subjected to different selective pressures along their Iberian distribution. In light of the above, C. austriaca may offer a useful model system in which to explore phylogeographical patterns in southern Europe, as well as the conflicts between processes driving morphological sexual divergence. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106 , 210–223.     

Biology and ecology of three species of Australian Dragonets (Pisces: Callionymidae)

Callionymus sublaevis, C. calcaratus and C. calauropomus collected from Moreton Bay and offshore Queensland, were studied biologically and ecologically and the findings compared with other callionymid fishes from Australian waters and other areas. Predominant preys types included penaeid prawns, pelecypods and poly-chaetes. Differences in temporal feeding intensity and prey types eliminated competition in some cases. Through brain pattern analyses, these callionymids were shown to be predominantly sight feeders even at depth, although gustatory feeding also increased slightly with depth. Sex ratios in C. sublaevis were almost even, while C. calauropomus had a predominance of males. C. calcaratus had a predominance of females, but considerable variation occurred on a seasonal basis. Although considerable variation was found in spawning times and spawning period length, the histological changes that occurred in the development of oocytes was similar. The ovarian cycle in C. sublaevis was studied in detail and found to be typical of most teleosts. Length-weight regression coefficients in all species were significantly higher than 3.0, indicating that the weight increased faster than the cube of their length. In all cases females were heavier in older fish with the least difference in length-weight occurring between the males and females of C. calcaratus. Otoliths were found to be satisfactory and reliable for use as a method for age and growth determinations in two of the callionymids studied. Overlap of age groups was found in all species and this was mostly attributed to the length of spawning period. The dragonets studied here all reached age group IV+ and attained maturity usually by the second year. No evidence was found to indicate that males die after spawning as has been shown in C. lyra. Observations on predation by benthic piscivorous fishes and by one avian predator are reported.