Australian Museum Journal Larvae and juveniles of the deepsea "whalefishes" Barbourisia and Rondeletia (Stephanoberyciformes: Barbourisiidae, Rondeletiidae), with comments on family relationships

Shortform:
Paxton et al., 2001, Rec. Aust. Mus. 53(3): 407–425
Author(s):
Paxton, John R.; Johnson, G. David; Trnski, Thomas
Year published:
2001
Title:
Larvae and juveniles of the deepsea "whalefishes" Barbourisia and Rondeletia (Stephanoberyciformes: Barbourisiidae, Rondeletiidae), with comments on family relationships
Serial title:
Records of the Australian Museum
Volume:
53
Issue:
3
Start page:
407
End page:
425
DOI:
10.3853/j.0067-1975.53.2001.1352
Language:
English
Date published:
12 December 2001
Cover date:
12 December 2001
ISSN:
0067-1975
CODEN:
RAUMAJ
Publisher:
The Australian Museum
Place published:
Sydney, Australia
Subjects:
FISHES; DEEPSEA; TAXONOMY
Digitized:
12 December 2001
Available online:
12 December 2001
Reference number:
1352
EndNote package:
EndNote file
Title page:
Title page (12kb PDF)
Complete work:
Complete work (658kb PDF)

Abstract

Larvae of the deepsea "whalefishes" Barbourisia rufa (11: 3.7-14.1 mm nl/sl) and Rondeletia spp. (9: 3.5-9.7 mm sl) occur at least in the upper 200 m of the open ocean, with some specimens taken in the upper 20 m. Larvae of both families are highly precocious, with identifiable features in each by 3.7 mm. Larval Barbourisia have an elongate fourth pelvic ray with dark pigment basally, notochord flexion occurs between 6.5 and 7.5 mm sl, and by 7.5 mm sl the body is covered with small, non-imbricate scales with a central spine typical of the adult. In Rondeletia notochord flexion occurs at about 3.5 mm sl and the elongate pelvic rays 2-4 are the most strongly pigmented part of the larvae. Cycloid scales (here reported in the family for the first time) are developing by 7 mm; these scales later migrate to form a layer directly over the muscles underneath the dermis. By 7 mm sl there is a unique organ, here termed Tominaga's organ, separate from and below the nasal rosette, developing anterior to the eye. Larvae of the two species of Rondeletia can be distinguished by the presence or absence of developing spongy bone in the pectoral girdle and sphenotic by at least 9 mm and by the counts of the vertebrae, pelvic-fin rays, and dorsal hypural bones in smaller larvae. The presence of Tominaga's organ in the gibberichthyid Gibberichthys suggests that "the whalefishes", Barbourisiidae, Rondeletiidae, and Cetomimidae, as a group are paraphyletic, and that Rondeletia and Gibberichthys are sister taxa.