Microporella lingulata, Martino & Taylor & Gordon, 2020

Martino, Emanuela Di, Taylor, Paul D. & Gordon, Dennis P., 2020, Erect bifoliate species of Microporella (Bryozoa, Cheilostomata), fossil and modern, European Journal of Taxonomy 678, pp. 1-31 : 19-22

Microporella lingulata sp. nov.

urn:lsid:zoobank.org:act:A74444C9-3AA5-4A19-B08D-245169244E6A

Figs 9–10 ; Table 7

Diagnosis

Colony bifoliate, tongue-shaped. Ancestrula ascophoran with associated avicularium. Autozooids rounded quadrate. Frontal shield pustulose and pseudoporous; pustules flat-topped, pseudopores sometimes coalescent. Orifice transVersely D-shaped; hingeline smooth; oral spines lacking. Ascopore reniform, opening crescentic, covered by a plate pierced by pores arranged in rows. Avicularium single, at level with ascopore, oriented laterally or slightly distolaterally; crossbar complete; rostrum subtriangular, not channeled. Ovicells not personate.

Etymology

From the Latin ʻ lingulata ʼ, meaning tongue-shaped and referring to the shape of the colonies.

Material examined

Holotype

NEW ZEALAND • Unbleached specimen; FoVeaux Strait; [46°55.0′ S, 168°24.0 E]; [53 m]; NZOI St. B263; Recent; NIWA 144886 ( Fig. 9 ).

Paratypes

NEW ZEALAND • 1 specimen; same collection data as for holotype; NIWA 144887 ( Fig. 10 A–B) • 1 specimen; same collection data as for holotype; NIWA 144888 ( Fig. 10 C–D) • 1 specimen; same collection data as for holotype; NIWA 144889 ( Fig. 10 E–F) .

Additional material (not figured)

NEW ZEALAND • 2 specimens; same collection data as for holotype; NIWA 144890 , 144891 .

Description

COLONY. Erect, bifoliate, comprising a single, non-bifurcating branch, tongue-shaped, 4–6 mm long by 3–4 mm wide (0.5–1 mm at the tip), proximal end rounded, distal end truncate forming growing edge; basally unattached; interzooidal communications not observed. Apparent ancestrula ascophoran in morphology (damaged in scanned examples), about 300 × 185 µm, with an associated aVicularium; located on one side of branch close to but not at proximal extremity of colony, oriented proximally. New buds at distal growing edge oriented obliquely to colony axis, facing distolaterally to the left on the left side and distolaterally to the right on the right side; zig-zag seam between left- and right-facing zooids approximately parallel to axis but typically displaced from midline.

AUTOZOOIDS. Distinct with interzooidal boundaries marked by narrow grooves, usually rounded quadrate, slightly torqued, longer than wide (mean L/W = 1.28). Frontal shield conVex, pustulose, the pustules conspicuously flat-topped, about 20 µm in diameter; marginal areolae numbering about 8, elongate, larger at corners of zooids, ca 20–35 µm long by 10–15 µm wide; non-marginal pseudopores located in grooVes between flat-topped pustules, irregularly arranged, Variable in number and size (diameter 10–20 µm), sometimes coalescent.

ORIfICE. TransVersely D-shaped, significantly wider than long, hingeline straight or slightly conVex, without teeth or condyles; oral spines lacking; operculum smooth.

ASCOPORE fIELD. Bordered by a thick rim of gymnocystal calcification, located moderately close to orifice, about 70 µm below, separated from it by non-porous cryptocystal calcification with smaller than aVerage pustules; broad, reniform, 35–55 × 100–110 µm, opening crescentic, 10–15 × 70–85 µm, covered by a plate pierced by about 30–40 circular pores arranged in two rows, sometimes three rows at the outer ends.

AVICULARIUM. Single, moderately large, present in most autozooids, located on right of autozooids at the left side of colony and on the left of those at the right side; level with or distal of ascopore, oriented laterally or slightly disto-laterally; crossbar deep, distal edge straight, proximal edge scalloped; opesia semielliptical; rostrum short, subtriangular, the distal end rounded and without a channel. Mandible long, ca 315–450 µm, lanceolate, pointed, slightly hooked, open examples mostly lying across ascopore. Intramural budding common in avicularia.

OVICELLS. Large, low in profile, not personate; calcification of identical fabric to frontal shield, continuous with frontal shield of distal zooid; pores irregularly scattered oVer surface; secondary orifice of ovicellate zooids shallower than infertile zooids.

Remarks

The ascopore of this new species is unusually wide compared with congeners, and the flat-topped cryptocystal pustules are another very notable feature. However, it is the peculiar tongue-shape of colonies that provides the easiest way of recognizing Microporella lingulata sp. nov. while at the same time posing questions about its mode of life. No substrate of attachment is visible, although it is possible that a small substrate is present but totally enVeloped by later growth. Regardless, it is difficult to understand how adult colonies were supported as there are no indications of rhizoids to root the colonies into a particulate substratum, nor are rhizoids known in any other species of Microporella . Functional autozooids were evidently budded at equal rates on both sides of the branch, arguing against the idea that colonies rested horizontally on the sea-bed with one side down against the sediment. The most plausible options are either a vertical orientation with only the rounded proximal end embedded in the sediment, or the entire colony living interstitially within a coarse substratum. According to St. B263 sediment data, the seafloor at the exact locality that yielded the specimens comprises medium and fine sand (62.5 to 500 µm particle size). GiVen the colonies are not rooted, it is possible that they just sit on the seafloor. The robust avicularian mandibles may have a supportive role, perhaps analogous to that in free-living lunulitiform bryozoans (e.g., Chimonides & Cook 1981).

Figures

Fig. 9. Microporella lingulata sp. nov., holotype, NIWA 144886 (unbleached), Recent, Foveaux Strait, New Zealand. A. General view of the tongue-shaped colony. B. Apparent ancestrula and periancestrular zooids. C. Group of ovicellate and non-ovicellate zooids. Some avicularia show the long, lanceolate mandibles. D. Close-up of an autozooid, having the avicularian mandible open, and an ovicellate zooid (right). Scale bars: A = 1 mm; B–D = 200 µm.

Fig. 10. Microporella lingulata sp. nov., paratypes, Recent, Foveaux strait, New Zealand. A–B. NIWA 144887. A. Group of ovicellate and non-ovicellate zooids. B. Close-up of an autozooid showing the reniform, cribrate ascopore. C–D. NIWA 144888. C. General view of the branch proximal tip including the ancestrular area. D. Close-up of damaged ancestrula and periancestrular zooids. E–F. NIWA 144889. E. Ovicellate zooids. F. Close-up of orifice, ascopore and aVicularium in an oVicellate zooid. Scale bars: A, C–E = 200 µm; B, F = 100 µm.