Hemismittoidea lanceolata, Hayward & Winston, 2011

Hayward, Peter J. & Winston, Judith E., 2011, Bryozoa collected by the United States Antarctic Research Program: new taxa and new records, Journal of Natural History 45 (37 - 38), pp. 2259-2338 : 2310-2311

Hemismittoidea lanceolata sp. nov.

( Figure 24 )

Material

Holotype. NMNH 1154052 : Eltanin cruise 9, station 740, 56 ◦ 06’ to 56 ◦ 07’ S, 66 ◦ 19’ to 66 ◦ 30’ W, 494– 384 m, 18 September 1963; a single small colony encrusting a fragment of Reteporella .

Paratypes. NMNH 1154050 , VMNH 013673.00: same data as holotype; two further small colonies on Reteporella fragments .

Description

Colony encrusting, unilaminar in present material. Autozooids irregularly hexagonal, separated by distinct sutures; frontal shield gently convex, smooth, with a single series of large, conspicuous, closely spaced marginal pores. Primary orifice wider than long, proximal rim with a broad, deep lyrula occupying half total width, its free edge convex, with bluntly cusped corners; condyles large and conspicuous, down curved, with fine ridges radiating to a broadly rounded, finely denticulate edge. Six spines closely spaced in an arc around distal border of orifice. Peristome developed laterally and proximally, with a deep mid-proximal pseudosinus, on each side of which the rim is produced as a prominent lobe. An adventitious avicularium situated immediately proximal to the pseudosinus, proximally directed, the rostrum elongate, slender, tapered, with denticulate edge; palate with a triangular foramen, crossbar complete, stout, with a thick, rectangular, median columella. Characteristic of the genus, the avicularium arises from a marginal pore on one side of the orifice only: in Figure 24A this is to the right, and the pores series can be seen to stop short of the peristome. Ovicell slightly wider than long, flattened frontally, with a gently arched aperture; smoothly calcified, perforated by numerous (> 30) small pores.

Measurements

Autozooid length (n = 20) 0.53 ± 0.05 mm (mean ± SD); autozooid width (n = 20) 0.39 ± 0.03 mm.

Etymology

Latin, lanceolatus: spear-like, with reference to the slender frontal avicularium.

Remarks

In its six oral spines, deeply notched peristome and lanceolate avicularium, Hemismittoidea lanceolata sp. nov. has a superficial resemblance to the New Zealand species, Hemismittoidea hexaspinosa (Uttley and Bullivant, 1972) , as described and figured by López Gappa (1986) from Burdwood Bank and the Beagle Channel. However, the avicularium of that species is asymmetrically placed, to one side of the peristomial pseudosinus, and its crossbar lacks the stout, rectangular columella seen in the new species. Further, the frontal shield of Lopez Gappa’s material has grossly nodular frontal calcification and a proportionately larger ovicell, with fewer, rather irregular pores.

Figures

Figure 24. Hemismittoidea lanceolata sp. nov. (A) Autozooids at the colony margin, showing morphology of condyles and lyrula; (B) ovicelled zooids. Scale bars: 0.25 mm.