Bulletin of the Museum of Comparative Zoology at Harvard College (1985-1988) (20468634236)

Title: Bulletin of the Museum of Comparative Zoology at Harvard College

Identifier: bulletinofmuseum15119851988harv (find matches)

Year: 1985-1988 (1980s)

Authors: Harvard University. Museum of Comparative Zoology

Subjects: Zoology

Publisher: Cambridge, Mass. : The Museum

Contributing Library: Harvard University, Museum of Comparative Zoology, Ernst Mayr Library

Digitizing Sponsor: Internet Archive

Text Appearing Before Image:

298 Bulletin Museum of Comparative Zoology, Vol. 151, No. 5

Text Appearing After Image:

Figure 16. Caudal skeleton of A. Hysterocarpus (40 mm SL). Johnson, 1984; Patterson, 1968; Rosen, 1973; Rosen and Patterson, 1969). The bas- al perciform caudal skeleton has been de- scribed by Gosline (1961) as having three epurals, two independent uroneural ossi- fications, and the hemal arches on the pen- ultimate and antepenultimate vertebrae autogenous. Patterson (1968) further char- acterized the basal Perciform caudal skel- eton as having, among other features, a low neural crest on the penultimate ver- tebrae. Epural Reduction. In labrid (Fig. 15C; see also Ford, 1937) and cichlid (Fig. 15A; see also Vandewalle, 1973) taxa there are two epural bones in the caudal skeleton. Among perciforms the primitive condi- tion, as found in the Embiotocidae (Fig. 15D), Pomacentridae (Fig. 15B), and most of the outgroup taxa examined (e.g.. Fig. 15E), is the possession of three epurals (see also Gosline, 1961). Although exceptional among embiotocids, individuals of Hys- terocarpus (Fig. 16) and Micrometrus are occasionally found with only two inde- pendent epurals. In these individuals the anomaly appears to be the result of fusion. In young Hysterocarpus, three separate epurals are present, whereas in the adult these are occasionally united along a por- tion of their border. The labrids and cich- lids bear no trace of a third epural at any time during ontogeny. Despite the somewhat mosaic distribu- tion of epural reduction among phyloge- netically disparate acanthomorph taxa (e.g., reduction occurs in a range of ser- ranid lineages as well as in a number of "paracanthopterygians" (Rosen and Pat- terson, 1969)), three epurals is undoubt- edly the primitive condition for perco- morphs (Patterson, 1968). In view of this ive interpret the reduction of epural number in the Lahridae and Cichlidae as a synapomorphy uniting the two clades. Uroneural Ossification. In common with a range of perciform taxa, the la- broid caudal skeleton has but a single uro- neural ossification (Gosline, 1961). In the Embiotocidae and Cichlidae, the uro- neural is autogenous, as it is in all out- group taxa examined (e.g.. Fig. 15E). Em- biotocids differ from outgroups, however, in having the uroneural elements very closely applied to the urostyle (Fig. 15D); nonetheless the uroneural can easily be- dissected free of the urostyle without damage to either element. In the Poma- centridae and Labridae the uroneural ele- ment is completely fused with the uro- style, resulting in a urostyle/uroneural block with no suture evident between the two elements (e.g.. Fig. 15B). In labrids, hypurals 4 and 5 are also fused to the uro- neural/urostyle block (Fig. 15C; see also Ford, 1937), a condition we consider to be synapomorphic for members of the Lab- ridae. Complete fusion of the uroneural with the urostyle, and the obliteration of all trace of a former siitural union, is inter- preted as a synapomorphy uniting the pomacentrid and labrid clades. Antepenultimate Vertebrae. Primitive- ly among perciforms, the hemal arch of

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