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Zoology Publications from Victoria University of Wellington—Nos. 54 to 57

Comparison with Japanese Specimens

Comparison with Japanese Specimens

We have not seen Tanaka's or Herre's specimens, but their descriptions of them were full, and these, together with the accompanying illustrations, give us no reason to believe that our specimens are specifically distinct from C. barbifer. In Table 1 we list the proportional dimensions of our specimens for comparison with those from Tanaka's and Herre's accounts. In extracting Tanaka's and Herre's dimensions we have excluded a few, such as head length to 1st gill-opening, which apparently were measured differently from ours, i.e., probably they were point to point measurements rather than projected distances along the main axis of the body. If it is assumed that the remaining dimensions which we include in Table 1 were measured in a comparable fashion with ours, it can be seen that there are still differences between all four specimens. Some of these between Tanaka's and Herre's specimens were no doubt what Herre referred to, but did page 7not itemise in his 1936 account, where he regarded them as being due to sex and age. We are not able to comment on the extent to which any of these differences are attributable to sex, but we do believe that many of them can feasibly be regarded as expressions of growth-change and hence age.

If we are correct in this view, then the growth changes in C. barbifer are generally in accord with those of other squaloid sharks, as outlined in Garrick (1960, p. 546). The data for C. barbifer indicate that with growth there is a proportionate decrease, relative to total length, in the length of the head (evidenced in this case only by length of snout in front of mouth), the length of the caudal fin, the horizontal diameter of the eye, and the height of the dorsal fins. The prominent nasal barbel of Cirrhigaleus, a unique structure in the Squaloidea, must also undergo a marked relative decrease in length with growth, since Herre's data for this in his 555 mm specimen translate to 7.4% of total length, whereas in Tanaka's 855 mm specimen and our 922 mm and 1082 mm specimens it is only 4.4%, 4.7% and 5.1% respectively. The only other feature which shows marked change is the length of the anterior margin of the pectoral fin—16.8% of total length in Herre's small specimen and 14.5% and 14.8% in our specimens. This decrease, if valid, is at variance with Garrick's (1960, p. 548) statement on the pectoral fin of other Squaloidea, which "compared with the total length ... may remain reasonably constant, or more often will show a slight increase".

Points of disagreement between Tanaka's and Herre's descriptions (including their illustrations) and our specimens are as follows. Tanaka stated (p. 152) "the anterior edge of upper lip beneath end of first third of eye and angle of mouth beneath beginning of last third", but his illustration (Plate 41) shows the anterior edge of the upper lip below about middle to last third of the eye, and angle of mouth behind the eye. Our specimens agree better with Tanaka's illustration than with his description. Tanaka noted in his generic diagnosis of Cirrhigaleus (p. 154) that there is "no pit or keel on root of caudal". We agree, from our specimens, that there are no precaudal pits, but there is a definite longitudinal dermal keel ventrolaterally on each side of the caudal peduncle. This keel, which is low and blunt-topped (see Plate 2) extends from the level of the posterior end of the second dorsal fin back on to the anterior part of the caudal fin. It is, therefore, similar to but less obvious than the comparable keels in Squalus species. Herre (1935, p. 124) described a similar keel from his specimen of C. barbifer. Herre's illustrations of his specimen agree with ours except that he shows the snout tip as much blunter in ventral view, while in lateral view the dorsal profile from the head back to the first dorsal fin is strongly convex and elevated. We do not place significance on the difference in snout tip shape, and we suggest that the elevated predorsal profile of Herre's specimen was probably due to distortion in preservation.