Setosinella prolifica Canu & Bassler, 1933

Martino, Emanuela Di & Taylor, Paul D, 2012, Pyrisinellidae, a new family of anascan cheilostome bryozoans, Zootaxa 3534, pp. 1-20 : 9-11

Setosinella prolifica Canu & Bassler, 1933

( Figs 13−22 ; Table 3 )

Setosinella prolifica Canu & Bassler, 1933: 41 −42, pl. 9, figs 7−8.

Material examined. Holotype: USNM 73903, Paleocene, Vincentown, New Jersey, USA; NHML D33347 (encrusting another bryozoan), details as for holotype.

Description. Colony encrusting, multiserial, unilaminar. Growing edge stepped, budding pattern apparently intrazooidal. Pore windows (mean L = 26 µm, mean W = 13 µm) visible in transverse vertical walls at colony growing edge, oval, facing frontally. Ancestrula small (L = 125 µm, W = 100 µm), resembling later autozooids with two solid oral spines. Autozooids small, distinct, separated by deep furrows, rounded hexagonal or oval, longer than wide (mean L/W = 1.46). Gymnocyst narrow, better developed proximally to the opesia, separated from cryptocyst by salient mural rim together with distal rim of opesia forming a pear-shaped outline. Cryptocyst extensive, deep, shelf-like, generally flat except for a very slight median convexity, finely granular and perforated by two small circular opesiules (D = 10 µm) ( Fig. 22 ) usually obscured by sediment or cement. Opesia semielliptical, limited distally by the mural rim and proximally by a transverse salient trabeculum attached to the mural rim. Oral spine bases numbering seven or eight in non-ovicellate zooids, six in ovicellate autozooids, closely spaced in an arch around the distal margin of the opesia; spine diameters ranging from 10 to 20 µm, variability independent of their position in the arch. Ovicells numerous, hyperstomial, globular, prominent, slightly broader than long, smooth, the ectooecium completely calcified, resting on proximal gymnocyst of distal zooid and indenting its mural rim. Avicularia interzooidal numerous, long and narrow, confined to furrows between autozooids, orientated obliquely distally. Gymnocyst variably developed, narrower laterally, more extensive proximally and distally. Cryptocyst generally narrow, broadest proximally. Opesia teardrop shaped. Rostrum longer than wide, truncated distally, the tip open or channeled. Two small sharp condyles present. Vicarious avicularia rare ( Fig. 15 ), triangular, distally orientated, generally observed at the margin of the colony. Gymnocyst narrow, more extensive laterally. Cryptocyst broadest proximally. Rostrum long and narrow, truncated distally, the tip open or channeled.

Remarks. Canu & Bassler (1933) described small, perforated distal kenozooids surmounting some of the autozooids in this species. These structures are reinterpreted here as oval pore windows visible at the growing edge of a colony fouling an older colony in the type specimen. They also reported four oral spines but a greater number (6-8) is clearly evident in SEM images of the holotype and the NHML topotype specimen. The latter specimen also provides evidence that the opesiules hypothesized to exist by Canu & Bassler (1933), but not actually observed by them, are indeed present in Setosinella prolifica .

Distribution. Thanetian (Paleocene), Vincentown Limesand of New Jersey, USA.

N, Number of colonies and number of zooids measured; SD, standard deviation.

Figures

FIGURES 13 − 18. Setosinella prolifica Canu & Bassler, 1933, USNM 73903, holotype, Paleocene, Vincentown Limesand, Vincentown, New Jersey, USA. 13. ovicellate and non-ovicellate autozooids, scale bar = 200 µm; 14. ovicellate autozooids and interzooidal avicularia, scale bar = 100 µm; 15. ancestrula, early astogeny and vicarious avicularium visible at the colony growing edge (centre lower right), scale bar = 200 µm; 16. growing edge of colony fouling an older colony, scale bar = 200 µm; 17. close-up of an ovicellate autozooid and two interzooidal avicularia, scale bar = 100 µm; 18. detail of colony growing edge showing a distal pore window, scale bar = 100 µm.

FIGURES 19 − 22. Setosinella prolifica Canu & Bassler, 1933, NHML D 33347, Paleocene, Vincentown Limesand, Vincentown, New Jersey, USA. 19. view of colony encrusting another bryozoan, scale bar = 100 µm; 20. ovicellate and nonovicellate autozooids, scale bar = 100 µm; 21. close-up of an interzooidal avicularium, scale bar = 20 µm; 22. close-up of a zooid showing two small circular opesiules, scale bar = 20 µm.

Tables

TABLE 3. Measurements (in μm) of Setosinella prolifica Canu & Bassler, 1933

	N (colonies, zooids)	Mean	SD	Range
Zooid length	2, 20	302	41	221–349
Zooid width	2, 20	206	22	177–238
Orifice length	2, 20	75	10	54–92
Orifice width	2, 20	79	10	66–96
Ovicell length	2, 10	120	4	116–126
Ovicell width	2, 10	146	15	126–165
Cryptocyst length	2, 20	148	23	125–167
Cryptocyst width	2, 20	178	25	131–219
Avicularia length	2, 20	227	14	211–244
Avicularia width	2, 20	70	9	57–77