34 



ONTOGENY AND SYSTEMATICS OF FISHES-AHLSTROM SYMPOSIUM 



sional sheet while emphasizing characters which are most useful 

 in identifying the actual larva from the drawing. Such characters 

 include the fins, pigmentation patterns, and details of the head 

 such as the jaws, spines and eyes. Internal structures such as 

 myomeres, the gut, cleithrum, and posterior end of the noto- 

 chord may also be emphasized but without masking important 

 external characters. Details of other internal structures as well 

 as shading or stippling for contrast are best excluded or de- 

 emphasized to maintain clarity. Pigmentation is important in 

 identification of most larvae and should be depicted clearly. 

 External melanophores can be drawn with a fine-tipped pen as 

 realistically as possible. Internal pigmentation can be effectively 

 represented by using light stippling with a smaller sized pen- 

 point. Care must be taken to avoid confusion of internal struc- 

 tures with pigmentation. 



Specimens selected for illustration should ideally be those of 

 the best condition available and representative of the particular 

 developmental stage in both pigmentation pattern and mor- 

 phology. The number of specimens to be illustrated is deter- 

 mined by the nature and objective of the publication, the amount 

 of material available in various size groups, and the degree of 

 morphological and pigmentation change undergone by the par- 

 ticular species during ontogeny. Specimens from described series 

 should be archived in a museum collection for proper care and 

 future reference after completion of the illustrations, and catalog 

 numbers should be published. 



The detailed drawing begins with an accurate body outline 

 showing the proper body proportions and position of fins and 

 critical pigment spots. This is most easily achieved by drawing 

 in light or blue pencil from a camera lucida-equipped micro- 

 scope. Other methods include drawing from a projection of a 

 slide transparency of the specimen or tracing a photograph. By 

 convention the lateral view of the larva is drawn, with the head 

 to the left. The exception to this is made with right-eyed pleu- 

 ronectiforms. In some instances a dorsal or ventral view is also 

 necessary to clarify a pigment pattern or laterally projecting 

 morphological structures. If sketching through a camera lucida, 

 it is helpful to use a magnification which allows the entire spec- 

 imen to be in the field of vision as long as important details 

 remain visible. Any resulting distortions at the periphery of the 

 field can be compensated for by differentially focusing the mi- 

 croscope on the particular region involved while carefully pen- 

 cilling along the image, then reconstructing a smooth line where 

 disjointed lines meet. Problems involving specimens that are 

 too large or too small can often be overcome by using lens 

 adapters or eyepieces of lower or higher magnification. Large 

 specimens may require being drawn in sections which are later 

 pieced together. This original sketch should be made large enough 

 to clearly indicate fine details such as the full complement of 

 fin rays, but not excessively so with the result of producing lines 

 which bleed in the final reduction for publication. Related to 

 this is the use of appropriate sizes of pen points which produce 

 lines fine enough to draw minute details yet not be lost in re- 

 production. Therefore, in determining the original size of each 

 drawing, thought should be given to the desired reduction ratio 

 as well as the number of illustrations comprising each plate. An 

 opaque projector is most useful for obtaining a specific size for 

 the final drawing from the initial sketch, but photocopy reduc- 

 tions also work well. With this final pencilled sketch, the illus- 

 trator can work with the larva under a microscope as a reference 

 to complete details of the drawing before attempting to ink it. 

 A light table can be helpful when tracing or inking over a rough 



pencilled sketch. The illustrator should always have a set of 

 meristics of the specimen being drawn and an understanding of 

 the important characters to be emphasized. A thorough inspec- 

 tion for accuracy is essential to insure agreement between il- 

 lustrations and descriptive text, especially concerning pigmen- 

 tation and meristic elements with size and stage of development. 

 Ideally exact counts and measurements can be obtained directly 

 from the illustration, allowing easy identification of the larva. 



Illustrations are often designed for comparison of features at 

 different stages of development or for comparison of similar 

 features which occur among different taxa. Special care should 

 be taken to represent similar features in a consistent style from 

 illustration to illustration. For example, a partially ossified fin 

 ray element, an ossified fin ray, and a fin spine may each be 

 depicted in a consistent but slightly different manner so that the 

 illustration not only shows the number and position of fin ele- 

 ments but also the type of element and its relative stage of 

 development. 



Literature dealing with larval fishes contains a broad array of 

 illustrative styles, techniques, and quality. Many of these are of 

 limited use since they fail to meet the criteria discussed above. 

 Photographs frequently yield unsatisfactory results due to dif- 

 ficulties in focusing on small, transparent organisms so that all 

 body parts appear equally sharp, and they preclude emphasizing 

 inconspicuous but important features for identification. Color 

 illustrations in a variety of media, although potentially valuable, 

 particularly for xanthophores, are limited due to prohibitive 

 publication costs, poor reproducibility, and the absence of a 

 long-lasting color preservative. Half-tone illustrations (see Ahl- 

 strom, 1965) are effective but difficult to reproduce. These latter 

 two techniques may become more practical with advances in 

 photocopy technology. The preferred technique in widespread 

 use consists of pen and ink drawings done in black India ink. 

 Various styles of illustrations of diverse groups of larvae are 

 represented in Moser (1981) and in this volume which serves 

 as a useful overview. Poul Winther, George Mattson, and other 

 artists (Ahlstrom and Ball, 1954; Ahlstrom and Counts, 1955; 

 Bertelsen and Marshall, 1956; Ege, 1953, 1957, and 1958; Grey, 

 1955b; Moser, Ahlstrom and Sandknop, 1977; Moser and Ahl- 

 strom, 1970; Tuning, 1961; Richardson and Washington, 1980) 

 have been instrumental in establishing a fine style of pen and 

 ink drawings which we emulate and have found most effective 

 in its applicability to larval fish identification. We maintain a 

 degree of flexibility in technique and style which varies with the 

 taxonomic group under consideration but falls within the gen- 

 eral framework discussed above. 



Illustrating a fish egg poses a more difficult problem than 

 illustrating a fish larva and will be limited to a brief discussion. 

 Encapsulation by the chorion necessitates representing the three- 

 dimensional quality of the egg in the drawing while showing 

 important morphological and pigmentation characters of inter- 

 nal structures (Ahlstrom and Moser, 1980; Matarese and Sand- 

 knop, this volume) with as much clarity as possible. Difficulties 

 arise due to the superimposing of these characters from a two- 

 dimensional perspective, particularly when the chorion is or- 

 namented, when an oil globule(s) is present, and when the de- 

 veloping embryo is fully coiled. 



In spite of the more complex structural representation re- 

 quired, the same criteria of accuracy, clarity and consistency of 

 style apply to egg illustrations. The relative proportions of the 

 egg size to the size of the embryo, oil globule(s), and width of 

 perivitelline space, the number of myomeres, and length of gut 



