Escharifora d’ Orbigny, 1852

Taylor, Paul D., Martha, Silviu O. & Gordon, Dennis P., 2018, Synopsis of ‘ onychocellid’ cheilostome bryozoan genera, Journal of Natural History (J. Nat. Hist.) 52 (25 - 26), pp. 1657-1721 : 1674-1676

Genus Escharifora d’ Orbigny, 1852

( Figure 9 )

Type species

Escharifora argus d’ Orbigny, 1851a , by subsequent designation ( Canu 1913, p. 146). Cretaceous, Senonian [probably Maastrichtian], Néhou, Manche, Normandy, France.

Diagnosis

Colony erect, bifoliate ( Figure 9 (a)). Autozooids regularly hexagonal ( Figure 9 (a,c)); zooidal boundaries raised, sometimes with a sinuous median groove. Cryptocyst extensive, often with a ring of subcircular, pit-like voids around edge of the zooid ( Figure 9 (d,e)). Gymnocyst lacking. Opesia strongly subterminal, distance from edge of opesia to distal zooidal boundary equivalent to or greater than opesial length, occupying less than one-third of frontal surface; semi-elliptical, wider than long, with opesiular indentations, proximal edge concave. Ovicells hyperstomial, ooecium cryptocyst-like ( Figure 9 (f)). Avicularia vicarious, symmetrical ( Figure 9 (b)), half the width or less of an autozooid; opesia wider than long, semi-elliptical with opesiular indentations; rostrum concave-sided, pointed, floor deep.

Remarks

Escharifora is a distinctive genus with erect bifoliate colonies, autozooids having opesiae set well back from their distal margins and subcircular voids arranged in a row close to the outer edge of the autozooids ( Figure 9 (e)). It has been assigned either to Onychocellidae or Coscinopleuridae ( Voigt 1924a; Gordon and Taylor 2005, table 1). The latter family has highly distinctive avicularia with porous frontal walls (see Voigt 1956). Their absence in Escharifora argues against placing this genus in Coscinopeuridae ( Koromyslova et al. 2018). Bock (2017) listed 11 species of Escharifora , eight from the Cretaceous, two from the Oligocene of Germany [ E. substriata (Münster in Goldfuss 1826) and E. verrucosa Beissel, 1865 ] and one from the Miocene of New Zealand ( E. lawderiana Stoliczka, 1865 ). The Cretaceous species of Escharifora closely resemble the type species apart from some minor differences. Notably, in E. quoyiana ( von Hagenow, 1851) , the autozooidal opesia have teeth along their proximal and distal edges, and the opesiae of the avicularia have a median proximal slit (see Voigt 1979, p. 12, fig. 3). However, Escharifora lawderiana from the Miocene can only be assigned to ‘ Escharifora ’ in a loose sense ( Gordon et al. 2009, p. 296), and some of the other Cenozoic species once referred to this genus are ascophoran cheilostomes (Zágoršek and Gordon 2014). It seems likely that the genus is confined to the Cretaceous and the very basal Paleocene: the NHMUK collections contain a Danian specimen collected in 2003 from the basal calcarenite of the Meerssen Member at Geulhemmerberg Cave, near Maastricht, Netherlands.

Range

Cretaceous. Santonian to Paleocene (Danian).

Figures

Figure 9. (a–c), Escharifora argus d’Orbigny; syntypes, MNHN.F.A24605; Cretaceous, Senonian (probably Maastrichtian), Néhou, Manche, Normandy, France; (a) fragment of small branch; (b) avicularium; (c) part of a branch showing autozooids and avicularia. (d–f), Escharifora circe d’Orbigny; NHMUK BZ 339(a); Cretaceous, Campanian, Biron Formation, Caillaud, Charente Maritime, France; (d) centre of bifoliate branch; (e) autozooidal opesia surrounded by pitted cryptocyst; (f) ovicellate autozooid. Scale bars: a, c, d = 1 mm; b = 200 µm; e, f = 100 µm.