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Zoology Publications from Victoria University of Wellington—Nos. 33 and 34

L. Anguilla australis ?australis

L. Anguilla australis ?australis

Material Examined. One specimen, 75.7mm total length; Aust. Mus. regd. no. IA.2363; McCulloch Reef, Great Barrier Reef, Queensland, between 17° S. and 19° S.; transitional larva.

Description. Measurements in mm: standard length 74.9, head 5.8, snout 1.0, eye 1.1, interorbital 1.0, upper jaw 2.3, postorbital 4.0, pectoral 1.3, preanal 41.8, predorsal 40.3, depth just before eye 2.0, depth at pectoral origin 3.2, depth at anal origin 5.2. Myomeres 52 + 60 = 112. a–d = 1.

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Text-fig. 3.—Figs. A-C—L. Anguilla obscura, 49.6mm total length, IFO St. G 16. Fig A—Lateral view to show distribution of major vertical blood-vessels, intestine and myomeres at level of vent. Fig. B—Lateral view of head. Fig. C—Lateral view of caudal region. Figs. D-F—Anguilla australis australis, glass-eel, 57.9mm total length, Aust. Mus. regd. no. I.B.5289. Fig. D—Lateral view, to show distribution of deep pigment on spinal cord. Fig. E—Lateral view of head. Fig. F—Lateral view of caudal region to show deep pigment on spinal cord and scattered lateral pigment.

Text-fig. 3.—Figs. A-C—L. Anguilla obscura, 49.6mm total length, IFO St. G 16. Fig A—Lateral view to show distribution of major vertical blood-vessels, intestine and myomeres at level of vent. Fig. B—Lateral view of head. Fig. C—Lateral view of caudal region. Figs. D-F—Anguilla australis australis, glass-eel, 57.9mm total length, Aust. Mus. regd. no. I.B.5289. Fig. D—Lateral view, to show distribution of deep pigment on spinal cord. Fig. E—Lateral view of head. Fig. F—Lateral view of caudal region to show deep pigment on spinal cord and scattered lateral pigment.

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Body moderately elongate, compressed, tapering appreciably only at head and along posterior half of caudal region. Head short, about one-thirteenth of total length, not greatly differentiated from trunk; snout acute, one-sixth of head, projecting in front of lower jaw and turned noticeably downwards; nostrils well separated with the anterior one almost at tip of snout, the other just in advance of eye; eye round, about equal to length of snout; gape considerably oblique, extending to a point just in advance of pupil. Teeth difficult to distinguish. Pectoral a little longer than snout; dorsal low, originating only slightly in advance of level of vent; anal also low; caudal fin distinct from tips of dorsal and anal. Colour creamy brown with black pigment restricted to the chorioid of the eye.

Remarks. This specimen is a late leptocephalus which has taken on the elongate form of the elver. It has not yet become rounded in cross-section but is losing its transparency. The preanal myomeres number 52, compared with 39 in the elver. With a total of 112 myomeres and a short dorsal fin there is little doubt that the specimen belongs to A. australis and, considering its point of capture close in to the Queensland coast, to the Australian subspecies, A. australis australis. The specimen is not in the best condition and shows no distinctions from the larvae assigned to A. australis schmidti enabling certainty of subspecific identification.