Hoplitaechmella Voigt, 1949

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 : 1682-1683

Genus Hoplitaechmella Voigt, 1949

( Figure 14 )

Type species

Cellepora vespertilio von Hagenow, 1839 , by original designation. Cretaceous, early Maastrichtian, Rügen , Mecklenburg-Vorpommern, Germany . The type material of this species has been lost (see Voigt 1959) and no neotype has been designated. Although von Hagenow (1839) did not illustrate his species, two specimens from the type locality were figured in Marsson (1887, p. 9, fig. 15). No further material of this species has been described from Rügen but we here figure a Rügen specimen in the Voigt Collection ( Figure 14 (g–i)) .

Diagnosis

Colony encrusting, zooidal boundaries grooved ( Figure 14 (a)). Pore chambers present ( Figure 14 (e)). Autozooids rounded hexagonal. Cryptocyst extensive, granular. Gymnocyst variably developed proximally and laterally. Opesia D shaped to bell shaped ( Figure 14 (b)), small, about one-quarter of zooid length, terminal, lacking opesiular indentations and constrictions; oral spines present, usually numbering six; cryptocyst granular. Ovicells hyperstomial ( Figure 14 (h), the ooecium not granular and apparently of exterior wall ( Figure 14 (i)). Intramural buds common ( Figure 14 (c,h)). Avicularia of two main types: small interzooidal avicularia often located distolaterally of autozooids, symmetrical, opesia long, rostrum short ( Figure 14 (b)); large vicarious avicularia, rare, symmetrical, opesia either the same size as those of the interzooidal avicularia ( Figure 14 (g)), or long and distally tapering, rostrum extending over cryptocyst of distal autozooid, condyles developed ( Figure 14 (d)). Kenozooids with central foramen present ( Figure 14 (g).

Remarks

Aside from the type species, Voigt (1949) assigned four other species from the Late Cretaceous to Hoplitaechmella when he erected the genus. The dimorphic avicularia and oral spine bases are characteristic, as is the presence of pore chambers as well as autozooidal frontal walls that may have a narrow but appreciable marginal gymnocyst. The latter two characters in particular raise some doubts about the classification of Hoplitaechmella within Onychocellidae .

A poorly preserved colony from the Late Paleocene to Early Eocene Red Bluff Tuff of Chatham Island, New Zealand, was questionably assigned to Hoplitaechmella by Gordon and Taylor (1999). Otherwise, the genus is known only from the European and Central Asian Late Cretaceous ( Voigt 1949, 1951, 1962, 1967, 1979; Veenstra 1963) and Danian ( Berthelsen 1962).

Range

Cretaceous (Campanian) to Paleocene (Danian,?Thanetian),?Eocene (Ypresian).

Figures

Figure 14. Hoplitaechmella vespertilio (von Hagenow).(a–f) NHMUK D15590;Cretaceous,probably lower Maastrichtian, Trimingham, Norfolk, UK; (a) autozooids and small avicularia; (b) autozooid opesia with oral spine bases and a pair of small avicularia; (c) autozooid with a sheet-like lamina of additional cryptocystal calcification; (d) large vicarious avicularium; (e) damaged growing edge showing pore chambers; (f) early astogeny with apparent ancestrula arrowed. (g–i) SMF 29623; Cretaceous, lower Maastrichtian, Rügen, Mecklenburg-Vorpommern, Germany; (g) kenozooid (left) and vicarious avicularium with small opesiae; (h) ovicellate zooid containing apparent intermural bud; (i) detail of ovicell flanked by small interzooidal avicularia. Scale bars: a, c–h = 200 µm; b, i = 100 µm.