Abdobalistum thyrsus, Poyato-Ariza F. J. & Wenz S., 2002

Poyato-Ariza F. J. & Wenz S., 2002, A new insight into pycnodontiform fishes, Geodiversitas 24 (1), pp. 139-248 : 223-224

Abdobalistum thyrsus n. sp. ( Fig. 4C, D )

Palaeobalistum orbiculatum – Heckel 1856 pro parte: 229-233, pl. 10.

Palaeobalistum orbiculatum – Blot 1987: “type = lectotype ” 88-108, figs 42-48, pls 26-29.

HOLOTYPE. — MHML P 9830 ( Fig. 4C, D ; only known specimen).

ETYMOLOGY. — From the Latin substantive “thyrsus, -i”, close-branched cluster, panicle; in reference to its autapomorphic multiple scales attached to most contour scales.

TYPE HORIZON. — Early to middle Eocene.

TYPE LOCALITY. — Monte Bolca, Italy.

DIAGNOSIS. — As for genus (monotypic genus).

Genus Palaeobalistum Blainville, 1818 Balistes – Faujas de Saint Fond 1803: 132, 133, pl. 6.

Diodon – Volta 1809 (1796): 168, 169, pl. 40.

Palaeobalistum – Blainville 1818: 338, 339. — Heckel 1856 pro parte: 204, 205, 229-233, pl. 1, fig. 11a-b.

Pycnodus – Agassiz II, pt. 1, 1833: 17, pt. II: 190, 191. TYPE SPECIES. — P. orbiculatum Blainville, 1818 .

INCLUDED SPECIES. — Monospecific genus.

REVISED DIAGNOSIS. — Nursalliine fish with the following unique combination of reverted primitive and derived characters: body shape intermediate, non-discoid, maximum body height less than 60% of standard length, with dorsal apex absent; caudal pedicle differentiated; crenulations and grooves on vomerine and prearticular teeth absent; infraorbitals as a mosaic of small plates; hypochordal elements of caudal endoskeleton enlarged; urodermals not differentiated; scales completely ossified, covering the whole body; scale rows in different directions; double scale rows present; scale rows between the bases of the lepidotrichia of unpaired fins absent; ornamentation made of tubercles; 15 to 17 dorsal ridge scales, in point contact with each other; 18 to 21 ventral keel scales; seven or more spines on ventral keel scales.

Figures

FIG. 4. — Forms previously referred to the genus Palaeobalistum Blainville, 1818; A, P. orbiculatum Blainville, 1818, type species, holotype, MNHN BOL 0523. Photo Serrette; B, Oropycnodus ponsorti n. comb., lectotype, NMW.1854.XXXIX.38. Photo Schumacher, courtesy Ortwin Schultz; C, D, Abdobalistum thyrsus n. gen., n. sp., part and counterpart of the holotype, NMHL P.9830a-b. Photos courtesy P. Forey. Scale bars: A, 5 cm; B-D, 2 cm.