Microporella californica ( Busk, 1856 )

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 : 53-55

Microporella californica ( Busk, 1856)

Fig. 7 , Table 2

Lepralia californica Busk, 1856: 310 , pl. 11 figs 6–7.

Microporella californica – Osburn 1952: 381, pl. 44 fig. 2. — Dick & Ross 1988: 73, pl. 9 fig. c. — Soule et al. 1995: 139, pl. 48 figs a–c.

Material examined

USA • 1 colony of 40 zooids, 10 ovicellate, on rock; California, Pillar Point; 37°29′42.306″ N, 122°29′45.6354″ W; 24 Jul. 2020; I.A. Chowdhury and H. Lee leg.; SBMNH 704770 • 1 colony of 56 zooids, 13 ovicellate, on rock; California, Point Saint George; 41°47′7.588″ N, 124°15′18.8568″ W; 8 Jun. 2020; I.A. Chowdhury and H. Lee leg.; SBMNH 704773a • 1 colony of 60 zooids, none ovicellate, on rock; California, Point Saint George ; 41°47′7.588″ N, 124°15′18.8568″ W; 8 Jun. 2020; I.A. Chowdhury and H. Lee leg.; SBMNH 704773b • 1 colony of 30 zooids, none ovicellate, on rock; California, Point Saint George ; 41°47′7.588″ N, 124°15′18.8568″ W; 8 Jun. 2020; I.A. Chowdhury and H. Lee leg.; SBMNH 704773c • 1 colony of 20 zooids, none ovicellate, on rock; California, Point Saint George ; 41°47′7.588″ N, 124°15′18.8568″ W; 8 Jun. 2020; I.A. Chowdhury and H. Lee leg.; SBMNH 704773d • 1 colony of 80 zooids, 40 ovicellate, on rock; California, Trinidad Head South ; 41°3′22.960″ N, 124°8′47.562″ W; 3 Apr. 2020; I.A. Chowdhury and H. Lee leg.; SBMNH 704774 .

Description

Colony encrusting, multiserial, unilaminar, forming subcircular patches, typically encrusting rocks of variable size ( Fig. 7A ); three distal pore chamber windows visible at colony margin ( Fig. 7G ).

Autozooids hexagonal, rectangular, or irregularly polygonal, ZL = 415–789 µm (611±88 µm, N = 20), ZW = 258–539 µm (414±69 µm, N = 20), mean L/W = 1.48, boundaries marked by grooves ( Fig. 7B– C ). Frontal shield convex centrally, nodular, finely granular, sometimes with blunt umbo proximal to ascopore; with numerous (26–47), circular pseudopores, D = 6–12 µm; marginal areolae only slightly larger than pseudopores.

Primary orifice transversely D-shaped, OL = 91–130 µm (110±12 µm, N = 20), OW = 118–167 µm (144±14 µm, N = 20), mean OL/OW = 0.76, mean ZL/OL = 5.55; hinge-line straight, smooth, with minute trapezoidal to rectangular condyles close to lateral corners ( Fig. 7E–F ). Four, occasionally five, distal oral spines ( Fig. 7D, G ), becoming obscured by secondary calcification later in ontogeny, or by ovicell; spine base dark brown.

Ascopore depressed relative to adjacent frontal shield, close to orifice, no more than 1–2 ascopore widths from proximal margin, outlined by narrow, raised rim of gymnocystal calcification ( Fig. 7F ); ascopore opening transversely C-shaped, D = 30–35 µm, with small, denticulate, distal projection and radial denticulation.

Avicularia usually paired but sometimes single, AvL = 63–110 µm (78±12 µm, N = 20), AvW = 27–48 (38±5 µm, N = 20) µm, mean AvL/AvW = 2.05; flanking orifice at same level as ascopore ( Fig. 7E ); rostrum triangular, acute with distal channel, raised distally, directed distally or slightly distolaterally, crossbar complete. Mandible not observed.

Ovicell globular, wider than long, OvL = 153–288 µm (215±33 µm, N = 20), OvW = 228–395 µm (335±43 µm, N = 20), mean OvL/OvW = 0.64, overlying frontal shield of next distal zooid, sometimes slightly obscuring distal margin of maternal orifice; secondary calcification continuous with that of next distal zooid but more finely granular, with 21–32 circular, evenly distributed pseudopores, 5–17 µm in maximum diameter ( Fig. 7A–C ).

Ancestrula not observed.

Remarks

Microporella californica is a very well-known species, described over the years by numerous taxonomists, who have helped highlight its intraspecific variability. One of the most variable features seems to be the number of distal oral spines; Busk (1856) reported four in the original description, Dick & Ross (1988) three to five, Hincks (1883) six, and Osburn (1952) five to seven. However, caution must be exercised regarding the higher spine count reported by Osburn (1952), as it might stem from a potential misidentification of the species. A preliminary examination of specimens from SBMNH assigned to M. californica by Osburn, revealed the presence of several colonies of M. cribrosa and M. similis Chowdhury & Di Martino sp. nov.

The degree of development of the umbo proximal to the ascopore is also highly variable and probably linked to the environment, as seen in other species in this study.

Distribution and ecology

This species occurs along the Pacific coast from California to Alaska, from the intertidal zone down to 150 m depth. Colonies encrust shells, rocks, and sometimes algae ( Osburn 1952; Dick & Ross 1988; Soule et al. 1995).

Figures

Fig. 7. Microporella californica (Busk, 1856) (SBMNH 704770), Point Saint George, California, USA. A. Group of zooids, most ovicellate. B. Close-up of autozooids with paired avicularia, one zooid ovicellate.C. Ovicellate zooidswith acute frontal shield umbones hiding the ascopore.D.Autozooids with oral spines intact. E. Close-up of an orifice, with oral spine bases obliterated by secondary calcification, and avicularia. F. Close-up of the ascopore and orifice with condyles. G. Incomplete autozooids showing distal pore chamber windows. Scale bars: A–C, G = 500 µm; D = 200 µm; E = 100 µm; F = 50 µm.