562
Journal of Paleontology 91(3):554–565
(Figs. 1, 2), soft portions of dorsal and anal fins gently rounded with nine to 12 rays (Tables 1, 2), frontals bearing a shallow sagittal crest and smooth supraorbital margins (Fig. 4.1), a stout spine at the posteroventral angle of the preopercle (Fig. 4.3), a scaleless preopercular shelf (Figs. 1, 2), and a strong and expanded first haemal spine closely bound to the two anterior anal-fin pterygiophores (Fig. 6.2). Webelieve that these features (Starnes, 1988; Kon and Yoshino, 1997) provide substantial morphological evidence to justify the retention of Pristigenys and Pseudopriacanthus as valid genera. Some of the features shared by these two genera are not plesiomorphic, and thus may be considered as evidence for their sister-group relationship, e.g., the reduction of the number of procurrent caudal-fin rays, and presence of a black marginal band on dorsal, anal, pelvic and caudal fins (Johnson, 1984; Starnes, 1988). In particular, the possession of three procurrent caudal-fin rays in these genera is regarded as derived, considering that other priacanthids have four or five elements (Johnson, 1984; Starnes, 1988) and the primitive number of procurrent caudal-fin rays is higher in percoid percomorphs (see Johnson, 1984). Summarizing, the detailed reinterpretation of the skeletal
morphology of Pristigenys substriata suggests that this Eocene taxon forms a clade with the extant Pseudopriacanthus, and that this grouping can be considered the sister-group to all remaining extant priacanthid genera (Cookeolus, Heteropriacanthus, Priacanthus) (Fig. 7). According to Starnes (1988), Cookeolus represents the sister-group to Heteropriacanthus plus
Priacanthus.As a final remark, we note that the skeletal morphology of Pristigenys substriata and its putative sister-group relationship indicate that the evolutionary significance of certain phylogenetically relevant features used by Starnes (1988) should be reconsidered. In particular, the median sagittal crest of the frontals and the massive anterior haemal spines closely associated with robust anal-fin pterygiophores, which were interpreted as derived in Cookeolus, Heteropriacanthus,and Priacanthus by Starnes (1988), should be regarded as plesiomorphic for the family and their absence in Pseudopriacanthus as derived. A number of Eocene, Oligocene, and Miocene priacanthid
species have been referred to the genus Pristigenys (e.g., Arambourg, 1967; Danil’chenko, 1980; Fitch and Crooke, 1984; Pharisat, 1991; Micklich and Parin, 1996; Taverne and Nolf, 2010; Prokofiev, 2013). Of these, the Oligocene and Miocene species are currently assigned to Priacanthus (Bannikov, 2010), or, in certain cases (e.g., Pristigenys macropus; Arambourg, 1967), cannot be assigned to the family Priacanthidae (Prokofiev, 2013). As for the other Eocene taxa, they are exclu- sively based on partially articulated or isolated bones from Belgium and England, representing two species, Pristigenys rutoti and P. hermani (Stinton, 1980; Taverne and Nolf, 2010). As discussed above, many of the diagnostic features of the genus Pristigenys refer to the overall physiognomy and proportions of the body, meristics, and pigmentation, all features that cannot be observed in partially articulated or isolated skeletal remains (including otoliths; Taverne and Nolf, 2010). Furthermore, Pristigenys substriata differs from these two species from Belgium and England in having a shallow (vs. absent) sagittal crest on the frontals, smooth (vs. serrate) shelf overlying the preopercular sensory canal, a single stout spine at the posteroventral angle of the preopercle (vs. spine absent in
Table 1. Measurements for Pristigenys substriata (Blainville, 1818) from the Eocene of Monte Bolca, Italy. Values are as percentage of SL. Pre-
Standard length (mm)
MNHN F. Bol529
NHM P.16127- 16370
NHM P.19057
NHM P.15370- 15371
NHM P.9941- 14540
52.6 83.4 60.5
73.3 50.4
Body depth
Head length
Head depth
Orbit diameter
Snout length
53.8 37.6 46.9 18.2 11.0 55.7 36.6 43.2 14.1 11.0 53.2 37.1 41.6 16.8 11.4
59.0 39.9 46.6 17.8 12.6 56.7 42.0 49.2 19.6 10.9
Caudal peduncle length
11.9 9.1
11.4 10.6
11.7
Caudal peduncle depth
?
17.3 19.3
20.1 18.4
Mandible length
?
23.6 21.8
24.1 24.2
dorsal length
38.0 38.2 44.9
37.3 37.3
Dorsal- fin base length
52.6 52.8 50.7
53.8 51.9
Pre- anal
length 65.5
69.0 65.4
68.2 71.8
Anal-fin base length
24.3 32.2 28.9
31.9 22.4
Pre-
pectoral length
?
51.1 ?
50.3 47.0
Pre-
pelvic length
38.0 55.5 48.2
52.3 57.1
8.1 9.3 ?
11.7 10.1
First dorsal- fin spine length
Longest dorsal- fin spine length (5th)
29.4 26.1 30.0
32.7 ?
Longest dorsal- fin ray length (3rd)
19.5 29.1 27.1
35.6 27.3
First anal- fin spine length
10.0 15.3 13.2
? 11.9
fin spine length (3rd)
Longest anal-
16.9 22.3 ?
27.8 17.6
Longest anal- fin ray length (3rd)
19.7 30.9 21.8
37.9 21.8
Pelvic- fin
length ?
49.7 ?
57.7 ?
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