TYPE SPECIES. — Schizosmittina planovicellata Vigneaux, 1949 by original designation.

EMENDED DIAGNOSIS. — Colony encrusting with zooids arranged in alternating parallel rows or bilamellar. Frontal shield evenly pseudoporous with distinct marginal areolar pores. Orifice sinuate with distinct condyles, often corrugated; lyrula absent; oral spines evanescent, present on marginal zooids only. Avicularia present or absent, adventitious or vicarious, when adventitious often suboral and associated with the peristome. Ovicells with a peripheral band of rugose calcification and a broad, flat, pseudoporous frontal area. Basal pore-chamber windows or mural septula present.

REMARKS

The genus Schizosmittina was resurrected by Gordon (1984) and subsequently recorded in both fossil and Recent material from a wide geographical area. Gordon (1994) noted that he had examined Vigneaux’s type material of S. planovicellata, scanning a few isolated zooids and using this information to rediagnose the genus. The earliest occurrence is Schizosmittina ovicellata Zágoršek & Kázmér, 2001 from the Priabonian (late Eocene) of Hungary, followed by the Rupelian (early Oligocene) S. bathydonta (Brown, 1952) from New Zealand. Among extant species, four (S. bicornis, S. cinctipora, S. conjuncta, S. melanobater) are currently known from New Zealand waters (Gordon 1984, 1989), two (S. maplestonei and S. vitrea) from Australia (MacGillivray 1879), one (S. lizzya) from South Africa (Florence et al. 2007), and one (S. pedicellata) from the eastern Pacific off USA coast (Soule et al. 1995).

Schizosmittina planovicellata Vigneaux, 1949 (Fig. 5)

MATERIAL EXAMINED. — Figured syntype (Vigneaux 1949: 104, pl. 10, fig. 5), C.B.510-1. This specimen is here designated as the lectotype of the species.

TYPE LOCALITY. — Salles, Gironde, Aquitaine, France.

AGE. — Serravallian, middle Miocene.

DESCRIPTION

Colony encrusting, multiserial, unilaminar (Fig. 5A). Zooids arranged in parallel rows, distinct by deep furrows, subrectangular, twice as long as wide (mean L/W = 2.05). Frontal shield slightly convex, nodular, evenly pseudoporous; pseudopores circular, large, about 20 µm in diameter (Fig. 5A, B). Marginal areolar pores distinct, larger than pseudopores, about 35 µm in diameter (Fig. 5A, B, D). Orifice longer than wide, about 100 µm long by 70 µm wide, with a narrow, deep U-shaped sinus and two, rectangular, corrugated condyles (Fig. 5C); oral spines absent. A raised peristome, more developed proximally and laterally, hides the primary orifice, and encloses a small, oval suboral avicularium sloping inwardly, proximally directed and with a complete crossbar (Fig. 5D). Vicarious avicularia absent. Ovicells large, globular, pseudoporous covered by a band of rugose calcification continuous with the frontal shield of the next distal zooid (Fig. 5A, B, D). Basal porechamber windows visible along distolateral zooidal margins at the colony growing edge, elliptical, about 15 µm long by 10 µm wide (Fig. 5E).

MEASUREMENTS

ZL 478 ± 25, 452-519 (10); ZW 234 ± 22, 204-271 (10); OvL 149 ± 10, 136-167 (10); OvW 186 ± 13, 167-203 (10).

REMARKS

Schizosmittina planovicellata differs from the fossil congeneric species, S. ovicellata and S. bathydonta, in having an encrusting rather than an erect colony-form. Recent species also differ: S. maplestonei (MacGillivray, 1879) has a pair of frontal tubercles proximal to the orifice; S. vitrea (MacGillivray, 1879), S. conjuncta (Uttley & Bullivant, 1972) and S. melanobater Gordon, 1989 have a much broader, widely rounded sinus; S. cinctipora (Hincks, 1883) has large adventitious avicularia on the frontal shield; S. bicornis Gordon, 1989 is distinguished by a pair of prominences present on either side of the orifice; S. lizzya Florence, Hayward & Gibbons, 2007 has a subimmersed tripartite ovicell with a single, almost medial foramen. The five, stout oral spines present in S. pedicellata Soule, Soule & Chaney, 1995 link this species more with Schizomavella rather than Schizosmittina.