Microporella setiformis O’Donoghue & O’Donoghue, 1923

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 : 57-59

Microporella setiformis O’Donoghue & O’Donoghue, 1923

Fig. 9 , Table 2

Microporella setiformis O’Donoghue & O’Donoghue, 1923: 174 , pl. 3 fig. 21.

Microporella setiformis – Osburn 1952: 385, pl. 44 fig. 8. — Soule et al. 1995: 150, pl. 53 figs a–d. — Dick et al. 2005: 3752 , fig. 18c–d.

Material examined

USA • 1 living colony of 30 zooids, none ovicellate, on rock; California, Black Sand Beach; 40°24′50.5074″ N, 124°23′48.1056″ W; 9 Jun. 2020; I.A. Chowdhury and H. Lee leg.; SBMNH 704776a • 1 colony of 20 zooids, none ovicellate, on rock; California, Black Sand Beach ; 40°24′50.5074″ N, 124°23′48.1056″ W; 9 Jun. 2020; I.A. Chowdhury and H. Lee leg.; SBMNH 704776b • 1 colony of 60 zooids, 18 ovicellate, on rock; California, Black Sand Beach ; 40°24′50.5074″ N, 124°23′48.1056″ W; 9 Jun. 2020; I.A. Chowdhury and H. Lee leg.; SBMNH 704776c • 1 colony of 30 zooids, none ovicellate, on rock; California, Black Sand Beach ; 40°24′50.5074″ N, 124°23′48.1056″ W; 9 Jun. 2020; I.A. Chowdhury and H. Lee leg.; SBMNH 704776d • 1 colony of 40 zooids, none ovicellate, on rock; California Black Sand Beach; 40°24′50.5074″ N, 124°23′48.1056″ W; 9 Jun. 2020; I.A. Chowdhury and H. Lee leg.; SBMNH 704776e • 1 colony of 60 zooids, 13 ovicellate, on rock; California, Black Sand Beach ; 40°24′50.5074″ N, 124°23′48.1056″ W; 9 Jun. 2020; I.A. Chowdhury and H. Lee leg.; SBMNH 704776f .

Description

Colony encrusting, multiserial, unilaminar, forming subcircular patches, typically encrusting rocks of various sizes; pore chamber windows visible at the colony growing edge ( Fig. 9E ), circular to elliptical, three on distal margin and 4–5 on each distolateral vertical wall.

Autozooids rounded hexagonal or irregularly polygonal, ZL = 377–540 µm (470±48 µm, N = 20), ZW = 272–439 µm (348±45 µm, N = 20), mean L/W = 1.30; boundaries marked by grooves between slightly raised vertical walls. Frontal shield flat to slightly convex, finely granular, with 52–89 circular pseudopores (D = 5–12 µm) and 10–12 circular to elliptical, marginal areolae per side, clearly distinguishable from pseudopores by their larger size (D = 10–22 µm) ( Fig. 9A–B ).

Primary orifice transversely D-shaped, OL = 114–139 µm (124±8 µm, N = 10), OW = 120–148 µm (133±8 µm, N = 10), mean OL/OW = 0.93, mean ZL/OL = 3.80; outlined by rim of smooth gymnocyst; hinge-line straight, smooth, with two low, trapezoidal condyles at corners ( Fig. 9C ). Two oral spines observed in some zooids, later obscured by secondary calcification or ovicell ( Fig. 9F ).

Ascopore unusually small, circular (18–25 µm in diameter), with smooth margin, covering plate lacking ( Fig. 9C ); at same level as adjacent frontal shield, 2–3 ascopore widths from orifice, outlined by rim of gymnocystal calcification independent from that encircling orifice.

Avicularia small, single or paired, AvL = 40–51 µm (46±4 µm, N = 7), AvW = 21–30 µm (25±3 µm, N = 7), mean AvL/AvW = 1.85; located distally at same level as ascopore ( Fig. 9C ); crossbar complete ( Fig. 9D ); rostrum rounded-triangular, directed laterally or slightly distolaterally, rostrum tip only slightly raised. Mandible not observed.

Ovicell prominent, round, wider than long ( Fig. 9A, D ); OvL = 194–281 µm (242±33 µm, N = 6), OvW = 305–363 µm (332±21 µm, N = 7), mean OvL/OvW = 0.73; continuous with frontal shield of next distal zooid, obscuring distal margin of maternal orifice; calcification finely granular like that of frontal shield but with marked ribs; perforated by small pseudopores, 5–14 µm in maximum dimension.

Aberrant kenozooids smaller than autozooids or nearly as large, lacking opening such as orifice and ascopore but equipped with avicularium ( Fig. 9B , see asterisks).

Ancestrula not observed.

Remarks

Our material fits the description of Microporella setiformis , a species originally described from British Columbia, Canada ( O’Donoghue & O’Donoghue 1923).

Distribution and ecology

Microporella setiformis has been recorded from intertidal waters to over 100 m depth. The species ranges from Ketchikan, Alaska ( Dick et al. 2005) southward Channel Islands in southern California ( Soule et al. 1995).

Figures

Fig. 9. Microporella setiformis O’Donoghue & O’Donoghue, 1923 (SBMNH 704776), Black Sand Beach, Lost Coast, California, USA. A. Group of zooids, some ovicellate.B. Autozooids and kenozooids (white asterisks) at colony growing edge. C. Close-up of orifice, showing low condyles, ascopore, and avicularia with crossbar missing. D. Close-up of ovicellate zooids with avicularia showing complete crossbar. E. Close-up of marginal zooid showing exposed pore chamber windows.F. Group of autozooids with two oral spines, some indicated with arrows. Scale bars: A = 1 mm; B = 500 µm; C = 50 µm; D, F = 250 µm; E = 150 µm.