Eoverruca hewitti Withers, 1935

Jagt, John W. M., Jaskuła, Iwona, Witek, Anna & Jagt-Yazykova, Elena A., 2008, A new record of the Late Cretaceous cirripede Eoverruca hewitti (Verrucomorpha, Proverrucidae) from southern Poland, Zootaxa 1671, pp. 59-68 : 62-64

Eoverruca hewitti Withers, 1935

( Figs 2 , 3 )

Original description. Eoverruca hewitti Withers, 1935: 338 , text-figs 37, 38; pl. 44, figs 9–18.

Types. The holotype (NHM In. 27598) is a fixed scutum ( Withers, 1935: pl. 44, fig. 9a, b), 1.7 mm in length, from the upper Santonian ( Uintacrinus socialis Zone ) of East Harling, Norfolk, eastern England. Withers (1935) had a total of 64 valves; all of these are contained in the collections of the Natural History Museum, Department of Palaeontology (London), under registration numbers NHM In. 27280-27281, In. 27595-27607 and In. 27725-27748.

Material examined. NHMM 2006 024/1-30, comprising carinae, a single rostrum, movable and fixed scuta, movable terga, a single fixed?tergum as well as lateral valves; all from samples 3, 4A, 4B and 5 taken at the JeŻówka section ( Fig. 1 C; Table 1).

Description. Valves with transverse ridges sharp-edged, prominent, somewhat overhanging, and undulating on rostrum and carina; a few longitudinal ridges are seen on rostrum and carina; transverse ridges project as sharp points on outer margins of valves.

Carina ( Fig. 2 G, I) small (0.95–1.0 mm in length), semi-cylindrical, slightly asymmetric; length c. 1.5 times width (but damaged); barely bowed inwards; transversely strongly convex and well rounded; ornament of prominent, smooth transverse ridges (at least nine, as preserved), of varying width and narrow, step-like, occasionally undulating interspaces; basal margin irregular (but damaged), concave, and faintly produced laterally below every transverse ridge; apical portion damaged, but estimated to have projected freely to c. onethird the length from apex; basal portion concave.

Rostrum ( Fig. 2 H) small (0.85 mm in length, 0.7 in width, as preserved), semi-conical; basal margin irregular (but damaged); barely bowed inwards; transversely strongly convex to semi-carinate; estimated to have projected freely to c. half its length from apex; ornament as in carina, less well marked, with interspaces more or less flush with transverse ridges in single specimen available.

Fixed scutum ( Fig. 2 J) small (1.15 mm in length, 1.05 mm in width as preserved), triangular (but damaged), faintly curved on tergal side, faintly convex transversely; apico-basal ridge slightly raised, flat-topped, widening markedly towards basal margin, near-equal in width to occludent side of valve; tergal side obliquely inclined inwards, narrow, with two articular ribs; ornament of transverse ridges, projecting beyond both occludent and tergal margins, straight to undulating, with interspaces either narrow or of equal width; occludent side with additional longitudinal striation radiating from apical portion towards basal margin; striae more or less of similar strength. Inner side abraded, but apical portion estimated to have projected freely to c. one-third of length of valve.

Movable scutum ( Fig. 2 D) small (1.3 mm in length), narrower than fixed scutum; apico-basal ridge also narrower, prominently raised and of near-equal width towards basi-tergal angle; prominent growth ridges not downturned on occludent margin; ornament of transverse ridges, straight to slightly undulating, with longitudinal striation on occludent side, similar, more subdued, to that of fixed scutum ( Fig. 2 J); prominent premordial valve with irregular basal margin in one specimen ( Fig. 2 D, NHMM 2006 024/4), reminiscent of the one seen in Vulcanolepas osheai (see Buckeridge, 2000: fig. 4F, G; Southward & Jones, 2003; Yamaguchi et al., 2004).

Fixed?tergum ( Fig. 2 E) small (0.95 mm in length, damaged), subrhomboidal, faintly convex transversely; apico-basal ridge narrow, raised, produced at basal margin; ornament of transverse ridges, undulating and projecting laterally; scutal side damaged, leaving no trace of articular ribs.

Movable tergum ( Fig. 2 A–C) small (between 1.4 and 1.8 mm in length), elongate; apico-basal ridge central, fairly narrow, increasing in width towards basal angle, of regular curvature; carinal margins of equal length, forming c. 70 degrees angle; occludent margin concave, shorter than scutal margin; two articular ribs on scutal side, one prominent and extending from apex to middle of scutal; depression on scutal side of this, separating it from rounded occludent margin forming second rib; ornament of transverse ridges, straight, produced markedly along upper carinal margin, more or less subdued between articular ribs on scutal side.

Lateral valves ( Figs. 2 F, 3A–F) small, with thin edges (overall width between 0.9 and 1 mm), of varying height, and of two types; one with basal angle positioned near-centrally and, on inner surface, c. one-third of valve height marked with few, prominent growth lines; the other with basal angle close to one side and more than upper half with such lines; ornament of pronouced transverse ridges and (sub)central ridge, similar to other valves.

Figures

FIGURE 1. Map of Poland (inset A), showing the extent of Cretaceous strata; arrow denotes the Miechów area); B shows the outcrop at JeŻówka, while C presents a simplified log of the section exposed there with numbered sample series in the left-hand column. Samples 3, 4 A, 4 B and 5 have yielded specimens of Eoverruca hewitti Withers, 1935 (see also Table 1).

FIGURE 2. Eoverruca hewitti Withers, 1935. All specimens from the upper lower Campanian at JeŻówka (Miechów Trough, southern Poland), from samples 3, 4 A and 4 B (see Fig. 1, Table 1). A, movable tergum (NHMM 2006 024 / 1); B, movable tergum (NHMM 2006 024 / 2); C, movable tergum (NHMM 2006 024 / 3); D, movable scutum (NHMM 2006 024 / 4); E,? fixed tergum (NHMM 2006 024 / 5); F, lateral valve (NHMM 2006 024 / 6); G, carina (NHMM 2006 024 / 7); H, rostrum (NHMM 2006 024 / 8); I, carina (NHMM 2006 024 / 9); J, fixed scutum (NHMM 2006 024 / 10). All SEM; scale bars equal 200 μm, except in C, where it represents 500 μm. Note premordial valve in D [compare Vulcanolepas osheai (Buckeridge, 2000: fig. 4 F, G); see also Southward & Jones, 2003].

FIGURE 3. Eoverruca hewitti Withers, 1935. All specimens from the upper lower Campanian at JeŻówka (Miechów Trough, southern Poland), from samples 3, 4 A and 4 B (see Fig. 1, Table 1). A, lateral valve (NHMM 2006 024 / 11), B, lateral valve (NHMM 2006 024 / 12); C, lateral valve, interior (NHMM 2006 024 / 13); D, lateral valve (NHMM 2006 024 / 14); E, lateral valve, interior (NHMM 2006 024 / 15); F, lateral valve (NHMM 2006 024 / 16). All SEM; scale bars equal 200 μm.