Microporella modesta, 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 : 23-26

Microporella modesta sp. nov.

urn:lsid:zoobank.org:act:18FA46FC-2D1B-4464-B5EC-34A6D51D9DAF

Fig. 11 ; Table 8

Diagnosis

Colony erect, bifoliate; branches narrow. Autozooids rhomboidal. Frontal shield pustulose and pseudoporous; pustules densely-packed. Orifice transVersely D-shaped, oVer twice as wide as long; hingeline toothed, a large tooth at each extremity; sometimes a low cowl-like peristome developed distally; three or four oral spines. Ascopore reniform to elliptical, opening crescent-shaped, lined by denticles; ascopore hidden by prominent mucro in frontal view. Avicularium single, located proximally of ascopore, oriented distolaterally; crossbar complete; rostrum channelled. Ovicells not personate.

Etymology

From the Latin ʻ modesta ʼ, meaning modest, moderate and referring to the ascopore concealed beneath a mucro.

Material examined

Holotype

ALGERIA • Unbleached specimen; Yates Johnson leg.; Recent; NHMUK 1869.10.6.6a ( Fig. 11 A–C).

Paratypes

ALGERIA • 3 specimens; Same collection data as for holotype; NHMUK 1869.10.6.6b ( Fig. 11 D–F), 1869.10.6.6c ( Fig. 11G ), 1869.10.6.6d ( Fig. 11H ) .

Description

COLONY. Erect, bifoliate, branches narrow, strap-like, ca 5 mm wide with up to 15 linear series of alternating zooids on each side; growing edge stepped; interzooidal communications not observed.

AUTOZOOIDS. Distinct with interzooidal boundaries marked by a narrow groove between salient vertical walls of adjacent zooids, rhomboidal, longer than wide (mean L/W = 1.33). Frontal shield conVex, pustulose, the pustules densely-packed and up to 20 µm in diameter; marginal areolae numbering about 6, not always differentiated from pseudopores, sometimes elongate, ca 30 µm long; pseudopores circular, numbering up to about 50, arranged semi-regularly in grooVes between pustules (diameter 10–25 µm).

ORIfICE. Transversely D-shaped, over twice as wide as long, hingeline straight or slightly concave, equipped with a large tooth close to each end and numerous tiny teeth in between; low cowl-like peristome sometimes deVeloped distally around orifice; three or four oral spines (diameter 10–15 µm), a

spine just aboVe each proximolateral corner of orifice plus a single distal median spine or spines inwards of the two distolateral corners.

ASCOPORE fIELD. As a flared, raised area of gymnocystal calcification, located moderately close to orifice, ca 40 µm below, separated from it by non-porous pustulose cryptocyst field; reniform to transVersely elliptical, 25 × 60 µm, opening crescent-shaped, 5 × 30 µm, lined by denticles; prominent mucro proximal of ascopore with spine-like or flap-like oVerhang hiding ascopore in frontal aspect.

AVICULARIUM. Single, moderately large, present in the majority of autozooids on side closest to branch margin, positioned proximally of ascopore, close to mucro, oriented distolaterally; crossbar complete; opesia semielliptical, shallow; rostrum short, subtriangular, rounded distally and channelled. Mandible long, about 250–320 µm, pointed, toothed, lying proximally of ascopore when open. Intramural budding often observed in avicularia.

OVICELLS. Moderately large, subglobular or rounded quadrate, not personate, proximal arms forming bridge aboVe ascopore; calcification of similar fabric to cryptocyst but pustules smaller and more closely-spaced, continuous with frontal shield of distal zooid; pseudopores small, peripheral only, those near margins aligned in radial rows; orifice of oVicellate zooids partly hidden in frontal View.

Remarks

This is the only bifoliate species of Microporella known from the Mediterranean (coast of Algeria). The presence of a mucro projecting over the ascopore enables M. modesta sp. nov. to be readily distinguished from its bifoliate congeners described above, as well as the encrusting European species of Microporella (i.e., M. ciliata (Pallas, 1766) , M. marsupiata (Busk, 1860) , M. appendiculata (Heller, 1867)) . The

new species is also unusual in possessing oral spines which are mostly lacking in bifoliate species of Microporella , another exception being M. hastigera .

Figures

Fig. 11 (opposite page). Microporella modesta sp. nov., Recent, Algeria. A–C. Holotype NHMUK 1869.10.6.6a (unbleached). A. General view of the branch tip. B. Group of autozooids at the branch tip. C. Close-up of the orifice with four oral spine bases, suboral mucro concealing the ascopore, and avicularium with the long, pointed mandible open. D–F. NHMUK 1869.10.6.6b. D. Group of zooids, mostly ovicellate. E. Close-up of ovicells. F. Close-up of an orifice and two aVicularia, the one on the left with intramural budding. G. NHMUK 1869.10.6.6c, ascopore. H. NHMUK 1869.10.6.6d, damaged zooid with two aVicularia on the left zooidal margin. Scale bars: A, D = 1 mm; B = 200 µm; C, F–H = 100 µm; E = 500 µm.