摘要:

The naupliar instars ofPhyllodiaptomus annae(Apstein, 1907) are described and illustrated. A key for the identification of larval stages is given. Naupliar development of Diaptomidae as evidenced by descriptions from the literature is discussed in the light of phylogenetic relationships.

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1993.tb00295.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

The Octopodidae occur in virtually all benthic marine habitats; however, species in the family show little overt morphological differentiation. Subfamilies are currently defined by the presence or absence of an ink sac and the number of sucker rows (the presence of an ink sac and a single row of suckers are primitive characters) (Voss, 1988b); subfamily depth ranges arc cited in the diagnoses. Examination of external octopodid morphology through principal components analysis reveals that octopodid morphology correlates with geographic distribution. Low‐latitude, shallow‐water octopuses typically have narrower bodies and larger suckers on longer arms than do deep sea and high‐latitude species. Sucker size inversely correlates with depth distribution, as studies of sucker functional morphology predict (Kier&Smith, 1990). The same characters contribute in a very similar manner to the discrimination of species when grouped by subfamily and when grouped by mean depth distribution. That depth distributions, which correlate with morphology and with the loss of the ink sac, contribute to the definition of these subfamilies, suggests that the subfamilies constitute phenetically similar rather than monophyletic groups. Cladistic analysis is required to reassess octopodid phyl

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1993.tb00296.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Monophyly of the Neotropical Characidiinae is established based on 13 synapomorphies: (1) dorsal lamina of mesethmoid bone very narrow; (2) mesethmoid bone separated from vomer by a large block of cartilage; (3) anterior and posterior nasal openings widely separated; (4) dorsal portion of infraorbital bone 1 greatly expanded vertically, forming anterior margin of orbit; (5) gap between the dentary and the angulo‐articular; (6) lamellar portion of infraorbital bones 3–6 greatly reduced, especially in the posterior bones, where it may be completely absent; (7) contact between the parasphenoid and the pterosphcnoid bones; (8) laterosensory canal piercing the sphenotic bone; (9) auditory foramen of prooptic bone circular and reduced in size; (10) absence of medial process on posttemporal bone; (11) three or more unbranched pectoral‐fin rays; (12) medial process on the ribs of the fifth vertebra; and (13) absence of circuli on the apical field of the scales. An analysis of characiform morphology reveals that all characters previously used in the literature to diagnose the group are plesiomorphic, equivocal, or misapplied at this level of generality.SUMMARYAlthough virtually no phylogenetic evidence (in the sense advocated by Hennig, 1966) had been previously presented to support the monophyly of the Characidiinae, and most 'diagnostic' characters used by previous authors were found to be unacceptable in a cladistic classification, i t is still possible to diagnose the Characidiinae in a phylogenetic sense. This study revealed the existence of 13 synapomorphies supporting the monophyly of the group. Several of these synapomorphies, such as the modifications associated with the mesethmoid, the jaw bones, and the ribs of the fifth vertebra, are unique to the Characidiinae, thus providing a solid basis for recognizing the group as a monophyletic unit of characiform fishes. Demonstration of characidiin monophyly provides a solid foundation for further phylogenetic analysis of characidiin interrelationships, and higher level relationships among characiform f

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1993.tb00297.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Two genera and four species of discosauriscids,Discosauriscus potamites, D. pulcherrimus, Letoverpeton austriacumandL. moravicum, have previously been described from the Boskovice Furrow in Moravia. These laxa were differentiated primarily on the basis of proportional differences of the skull together with other morphological characters.Excavations at two localities in the Boskovice Furrow have produced new, relatively abundant, skeletal material. The specimens are preserved three‐dimensionally. In order to evaluate the differences in skull proportions, 17 variable characters on 70 skulls were measured. Statistical analysis demonstrates the existence of several morphological trends in the shape of the skull. However, no trend permits the division of this set of specimens into two clearly differentiated groups. The morphological differences used previously to define genera and species seem to be incorrect. Pending the discovery of distinct morphological differences, the Moravian discosauriscids can be considered as belonging to only one taxon:Discosauriscus austriacus(Makowsky, 1876

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1993.tb00298.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Phenotypic modulation is a common feature in haplochromine cichlids. External changes influence the phenotype within the limits set by the genetic program. Retinal development in the cichlidHaplochromis sauvageihas been observed in specimens reared in various chromatic environments and in darkness. Rearing in darkness led to the reduction of photoreceptor densities, the apparent loss of single cones and the enlargement of double cones. To a lesser degree, similar effects were observed in specimens deprived from short‐wave light. Ganglion cell densities were not affected by light deprivation. The light‐induced alterations could be the result of changes in developmental rates within the retina or of early degeneration. The modulation seems to cause a reduction of blue sensitivity, possibly for the benefit of luminosity or long‐wavelength detection. This would agree with the combination of decreased light intensity and a spectral shift towards the longer wavelengths as is the case in the natural environment of the Lake Victorian haplochromines. In that sense, the modulation is probably ada

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1993.tb00299.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY