Microporella dentata Chowdhury & Di Martino, 2024

Chowdhury, Ismael A., Martino, Emanuela Di, Lee, Hannah, Windecker, Claire C. & Craig, Sean, 2024, Diversity and distribution of intertidal Microporella (Bryozoa: Cheilostomatida) from California, European Journal of Taxonomy 932, pp. 34-68 : 39-41

Microporella dentata Chowdhury & Di Martino sp. nov.

urn:lsid:zoobank.org:act:B70AFEDB-8620-4902-B464-17A652381A30

Fig. 2 , Table 2

Diagnosis

Encrusting Microporella ; zooids with single or paired avicularia with channelled rostrum; frontal shield tubercular, pseudoporous with indistinct marginal areolae and well developed central umbo; orifice with two prominent condyles and serrated proximal margin; four oral spines; ascopore cribrate, placed in a triangular depression, close to orifice; ovicells umbonate, with conspicuous radiating ridges, imperforate except for marginal pores.

Etymology

Latin ‘ dentatus ’, toothed, alluding to the denticles and prominent condyles present on the proximal margin of the orifice of this species.

Type material

Holotype USA • 1 colony of 50 zooids, several ovicellate, on inner surface of red abalone shell; California, MacKerricher State Park, Fort Bragg ; 39°29′25.764″ N, 123°48′8.748″ W; 2 Feb. 2020; I.A. Chowdhury and H. Lee leg.; SBMNH 704789 .

Paratypes USA • 2 colonies of 40 zooids each, none ovicellate, on underside of small boulder; California, Greenwood; 39°7′45.0582″ N, 123°43′9.192″ W; 2 Feb. 2020; I.A. Chowdhury and H. Lee leg.; SBMNH 704790a–704790b .

Description

Colony encrusting, multiserial, unilaminar, forming circular patches, found encrusting red abalone shells ( Haliotis rufescens Swainson, 1822 ) or small boulders.

Autozooids rounded hexagonal to rectangular, ZL = 397–607 µm (494±54 µm, N = 20), ZW = 316– 522 µm (380±57 µm, N = 20), mean ZL/ZW = 1.30 ( Fig. 2A ), boundaries marked by grooves between slightly raised vertical walls. Frontal shield convex centrally, tubercular, coarsely granular, marked by radial ridges with circular pseudopores in grooves between ridges, 23–40 circular pseudopores, D = 7–20 µm; up to 10 circular to elliptical, marginal areolae per side, indistinguishable from pseudopores due to similar size.

Primary orifice transversely D-shaped, OL = 68–102 µm (86±8 µm, N = 20), OW = 84–116 µm (102±8 µm, N = 20), mean OL/OW = 0.84, mean ZL/OL = 5.74; hinge-line straight, serrated, with pair of sharply triangular condyles at corners ( Fig. 2C ). Four oral spines; proximalmost pair retained in ovicellate autozooids ( Fig. 2B, D ).

Ascopore in depressed triangular area outlined by distalmost ridges of frontal shield converging towards the centre ( Fig. 2C ) and forming the imperforate umbo proximal to ascopore ( Fig. 2B ); close to orifice, no more than 1–1.5 ascopore widths from proximal margin; ascopore opening 20–31 µm in diameter, cribrate, often obscured by proximal umbo ( Fig. 2C, E ).

Avicularium usually single, occasionally paired or absent, AvL = 58–112 µm (91±17 µm, N = 20), AvW = 35–55 µm (46±6 µm, N = 20), mean AvL/AvW = 1.98; located distolaterally on either side with rostrum tip at same level as ascopore or more proximally, proximolaterally to frontal umbo; crossbar complete; rostrum sharply triangular, narrowly channelled distally, with open, raised tip, directed distolaterally ( Fig. 2B, D ). Mandible triangular, slightly longer than rostrum (in Fig. 2B mandible length 90 µm, rostrum length 60 µm).

Ovicell prominent ( Fig. 2D–E ), rounded-quadrate, OvL = 172–201 µm (186±21 µm, N = 2), OvW = 200– 222 µm (211±15 µm, N = 2), mean OvL/OvW = 0.88, overlying frontal shield of next distal zooid, obscuring distal margin of orifice of maternal zooid; imperforate centrally, with a row of pseudopores all around the periphery inside the margin and areolae placed most-laterally; with radial ridges soon after formation but eventually covered by granulated frontal calcification from surrounding zooids and sometimes central, rounded, smooth umbo similar to that on the frontal shield.

Ancestrula not observed.

Remarks

The main character distinguishing this new species from the other species of Microporella is the serrated proximal margin of the orifice, which also bears two prominent, triangular condyles. The combination of a serrated orifice with a cribrate ascopore has been observed in Microporella elegans Suwa & Mawatari, 1998 from Japan. That species, however, differs in having reticulate pseudopores and avicularia directed laterally ( Suwa & Mawatari 1998). Microporella germana Dick & Ross, 1988 from Alaska is similar in the shape and position of the avicularium, in having a crenulated proximal oral margin, and in the number of spines; it differs in having an ascopore with lunate opening and smaller condyles ( Dick & Ross 1988). Additional similar species with a cribrate ascopore include: Microporella neocribroides Dick & Ross, 1988 from Alaska, which differs in having an orifice with smooth proximal margin and less prominent condyles ( Dick & Ross 1988); M. sanmiguelensis ( Soule, Chaney & Morris, 2004) which differs in having all zooids with paired avicularia ( Soule et al. 2004); M. santabarbarensis ( Soule, Chaney & Morris, 2004) , in which the ascopore is placed at the same level as the adjacent frontal shield rather than in a triangular depression ( Soule et al. 2004); and M. serrata Mawatari & Suwa, 1998 from Japan, in which the ascopore opening is reniform, rather than circular or elliptical ( Mawatari & Suwa 1998).

Distribution and ecology

Microporella dentata Chowdhur y & Di Martino sp. nov. is known from MacKerricher State Park beach to Pillar Point in California, USA. The colony in Fig. 2 encrusted a red abalone shell ( H. rufescens ), while the remaining colonies encrusted rocks, all in an exposed intertidal boulder field.

Figures

Fig. 2. Microporella dentata Chowdhury & Di Martino sp. nov., holotype (SBMNH 704789), MacKerricher State Park, California, USA. A. General view of colony. B. Group of autozooids, each with four oral spines and avicularia. The insert shows an avicularium with open mandible. C. Closeup of orifice with serrated hinge-line and ascopore. D. Ovicellate zooids with incomplete, developing ovicells.E. Paratype (SBMNH 704790a), Greenwood, California, USA. Ovicellate zooids with complete ovicells. Scale bars: A = 1 mm; B = 200 µm; C = 50 µm; D = 150 µm; E = 250 µm.