. Bulletin of the Natural History Museum Zoology. REVISED CLASSIFICATION FOR CERTAIN CIRRHITOID GENERA The cirrhitoids as a monophyletic lineage On the basis of several apparently synapomorphic character- istics (see below) the cirrhitoids would seem to be a mono- phyletic lineage, a conclusion implied by both Gill (1862) and Regan (1911) who described the group as a 'natural' one but gave no reasons for that conclusion. The derived characters on which I would base an hypothesised monophyly of the cirrhitoids are, taken in conjunction, a reduced number (15) of principal caudal fin rays, the un
. Bulletin of the Natural History Museum Zoology. REVISED CLASSIFICATION FOR CERTAIN CIRRHITOID GENERA The cirrhitoids as a monophyletic lineage On the basis of several apparently synapomorphic character- istics (see below) the cirrhitoids would seem to be a mono- phyletic lineage, a conclusion implied by both Gill (1862) and Regan (1911) who described the group as a 'natural' one but gave no reasons for that conclusion. The derived characters on which I would base an hypothesised monophyly of the cirrhitoids are, taken in conjunction, a reduced number (15) of principal caudal fin rays, the unbranched lowermost five to nine rays in the pectoral fin (usually with their tips produced beyond the fin membrane), the lower part of each cleithrum greatly expanded anteroposteriorly and meeting its antimere in a deep, carinate symphysis, an increased number of vertebrae relative to other percoids (26-35, comprising 10-16 abdominal and 15-21 caudal elements), and the presence, ventrally, in subadults of a peculiar, lipoid-filled sac (Fig. 3), free from the overlying hypaxial muscles, and extending from the urohyal, to which it is attached, to the anus, with the lipoidal material apparently contained in hexagonal compart- ments. To the best of my knowledge, this lipoid sac has not previ- ously been noted as a feature of subadult cirrhitoid fishes, nor indeed of any other perciforms except the stichaeid Lumpenus maculatus (see Falk-Petersen et al., 1984). I first observed it in small specimens (the so-called 'paperfish' stage) of Cheilodacty- lus pixi ca 43 to 44 mm standard length (Fig. 3), where its presence results in the 'pouter-pigeon'-like ventral profile of the paperfish stage in this and other cirrhitoid species (see photo- graphs in Whitley, 1957; Allen & Heemstra, 1976, and Nielsen, 1963). Subsequent dissections revealed a lipoid sac in members of all but two of the cirrhitoid families I have dissected (see p. 2). The exceptions are a chironemid, Chironemus marmor
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