Gomphonchoporus Vergoossen, 1999

Burrow, Carole J., 2003, Earliest Devonian gnathostome microremains from central New South Wales (Australia), Geodiversitas 25 (2), pp. 273-288 : 282

Genus Gomphonchoporus Vergoossen, 1999

TYPE SPECIES. — Gomphodus hoppei Gross, 1947 .

Gomphonchoporus hoppei ( Gross, 1947) HOLOTYPE. — Scale f 449 figured by Gross (1947: pl. 24, fig. 7) from a Late Silurian erratic boulder, north Germany. Vergoossen (1999b: pl. 4, figs 42-44) erected a neotype NNM 423034, from a Pridoli-aged erratic, Oosterhaule, northern Netherlands.

MATERIAL EXAMINED ( Table 1). — Two scales in sample C864, three scales including figured specimen MMMC 02563 ( Fig. 3F, G ) in C925, and two scales in Y4.

DESCRIPTION ( FIG. 3F, G )

These scales are up to 0.8 mm wide, relatively shallow, and wider than long. MMMC02563 ( Fig. 3F, G ) has numerous short, weak ridges along the anterior crown margin. The posterior part of the crown has broken off, creating concave postero-lateral edges ( Fig. 3G ), with no evidence preserved of a radial pore canal system. The neck is concave all round with “buttresses” on the posterior faces; the rounded base is shallow.

REMARKS

Vergoossen (1999b) erected the poracanthodidid genus Gomphonchoporus for scales which Gross (1947) had assigned to the ischnacanthidid genus Gomphonchus . Gross’ type material was from northern German erratic limestones (Pridoli), and the taxon has been recorded from Pridoli- Lochkovian deposits of the Baltic, northern Europe and Great Britain (Valiukevic˘ius 1998; Vergoossen 2000); Vergoossen (1999b) proposed a neotype (associated with a full range of variants) deriving from a Pridoli erratic collected from Oosterhaule, northern Netherlands. Gomphonchoporus hoppei has a relatively wide variety of scale forms, with some of the variants (particularly when poorly preserved) appearing indistinguishable to scales from R. porosus . Difficulty in separating scales of these taxa applies to Baltic samples comprising thousands of scales, as observed by Gross (1971) and Vergoossen (1999b), as well as to the small samples studied here.

Figures

FIG. 3. — Acanthodian tooth and scales from sample C925, Cookeys Plains Formation (early Lochkovian), central New South Wales, Australia; A, B, Nostolepis sp. tooth whorl MMMC02560 in occlusal (lingual edge at top) and posterior and lingual views; C, D, Gomphonchus sandelensis (Pander, 1856) scale MMMC02561 in crown and lateral views, with anterior edge to the left (crown riddled with hyphal borings); E, Trundlelepis sp., horizontal ground thin section of scale crown MMMC02562, anterior edge to left; F, G, Gomphonchoporus hoppei (Gross, 1947) scale MMMC02563 in crown and posterior views, anterior edge at top; H, I, Radioporacanthodes porosus (Brotzen, 1934) s.s. scale MMMC02564 in antero-crown and anterior views. Abbreviation: p, pore rows. Scale bars: 0.1 mm.