Cheilopora peristomata, Kuklinski, Piotr, Grischenko, Andrei V. & Jewett, Stephen C., 2015

Kuklinski, Piotr, Grischenko, Andrei V. & Jewett, Stephen C., 2015, Two new species of the cheilostome bryozoan Cheilopora from the Aleutian Islands, Zootaxa 3963 (3), pp. 434-442 : 435-436

Cheilopora peristomata n. sp.

( Figure 1 , A–D)

Material examined. Holotype: NHMUK 2014.12.5.2, colony encrusting oyster shell, RV Norseman, 16 July 2011, reef at Mid Boot Bay, Adak Island, Andreanof Islands, Aleutian archipelago, 51°44'16.5" N, 176°30'00.3" W, depth 10 m, SCUBA, coll. P. Kuklinski.

Etymology. The species names alludes to the elevated peristomial orifice.

Diagnosis. Colony encrusting, autozooids large, elongated. Frontal shield flattened, evenly perforated by large circular pseudopores. Primary orifice partly concealed by peristomial secondary orifice, which is campanulate to trifoliate in outline. Distal part of peristome comprises proximal edge of frontal shield of daughter zooid, separated by a pair of proximolateral sinuses from strongly projecting proximal rim that is angled over primary orifice at 70– 80° to frontal plane. Small oval paired avicularia at proximolateral corners of secondary orifice; rostrum lingulate, distally rounded, separated from semicircular opesia by thin crossbar. In ovicellate zooids, distal part of secondary orifice is formed by proximal edge of ooecium; ooecia subspherical, broader than long, entooecium coarsely granular-tubercular, evenly pseudoporous, ectooecium membranous.

Measurements. ZL 0.98–1.17 (1.07 ± 0.05), ZW 0.30–0.45 (0.39 ± 0.04). OrL 0.24–0.31 (0.27 ± 0.02), OrW, 0.25–0.31 (0.28 ± 0.02). AvL 0.10–0.15 (0.13 ± 0.01), AvW 0.06–0.09 (0.07 ± 0.01). OoL 0.24–0.36 (0.31 ± 0.03), OoW, 0.36–0.53 (0.42 ± 0.04).

Description. Colony encrusting, multiserial, unilaminar, irregular in form. Zooids large, elongate-hexagonal to rhombic, broadest in midline, tapering proximally, arranged in more or less regular rows in a chequered pattern, demarcated by sinuous sutures between adjacent vertical walls. Frontal shield flattened to slightly convex in distal half, surface granular, evenly perforated by numerous relatively large, round to irregular pseudopores over entire surface except for suboral peristomial area; pores becoming infundibular and the frontal shield somewhat more reticulate, with blunt projections between the pores, in ephebic zooids ( Fig. 1 , A, B). Primary orifice deep, corresponding to operculum, somewhat concealed by peristome. Peristomial secondary orifice cormidial, composed of two elevated parts with granular-tubercular external surface. Shape of secondary orifice varying significantly ( Fig. 1 , A–D); predominantly campanulate in non-ovicellate zooids, sometimes transversely oval or irregular in shape; reduced in size and trilobite in ovicellate zooids. Distal part of peristome comprising arcuate proximal end of frontal shield of daughter zooid, with rounded to angular proximolateral tips curved inward; proximal part represented by broad, elevated suboral proximal rim, trapezoidal in profile, slightly tilted distad at angle of 70–80° to frontal plane and overhanging about 1/5 of proximal area of primary orifice; though elevated and projecting, its edge may be transversely gently concave, with rounded to angular corners. Distal and proximal parts of cormidial peristome separated proximolaterally by deep pseudosinues of variable width, these positioned close to avicularian chambers. In ovicellate zooids, peristomial orifice distally restricted by proximal margin of entooecium that extends proximad on each side to terminate in angular projections at edge of pseudosinuses. Relatively small lateral-suboral avicularia at corners of orifice, typically paired, rarely single or lacking, displacing by more than half their length the margins of adjacent zooids ( Fig. 1 , B, C). Avicularian chamber oval, directed distolaterally to laterally, the rostral rim slightly elevated; rostrum lingulate, separated from semicircular opesia by thin crossbar. Ovicell prominent to subimmersed, subspherical, broader than long, its ectooecial calcification partly encroaching onto frontal shield of adjacent zooids, with weakly visible slit-like basal openings (areolar pores) flanking ooecium on each side ( Fig. 1 , D). Entooecial surface granular-tubercular, uniformly pseudoporous, sharply contrasting with larger frontal pseudopores. Interzooidal communications via multiporous septula. Basal wall fully calcified. Ancestrula and early astogeny not observed.

Remarks. Cheilopora peristomata n. sp. resembles the type species of the genus, C. sincera ( Smitt, 1868) , in: 1) elevated secondary orifice; 2) paired, oval lateral-suboral avicularia adjacent to peristomial pseudosinuses, and possessing lingulate mandibles directed distolaterally; and 3) slit-like areolar openings flanking entooecium on each side in frontal shield of distal zooid. The new species differs from C. sincera in following characters: 1) peristomial margins forming a complete circle in C. sincera but separated by deep U-shaped pseudosinuses in C. peristomata ; 2) suboral avicularia are almost constantly paired, rarely single or lacking, in the new species, the opposite of the situation in C. sincera ; 3) secondary orifice semicircular or rounded-quadrate in non-ovicellate zooids, irregularly semicircular to rounded-quadrate in ovicellate zooids in C. sincera (see Grischenko et al. 2007, p. 1126), but bell-shaped to transversely oval in non-ovicellate zooids, and sometimes trifoliate in ovicellate zooids of C. peristomata .

Distribution. The new species is currently known only from the type locality and thus can be categorized as a Pacific, high-Boreal, sublittoral species.

Figures

FIGURE 1. Cheilopora peristomata n. sp., holotype NHMUK 2014.12. 5.2, Adak Island, Andreanof Islands of the Aleutian Islands, Reef Mid Boot Bay, bleached: A, colony margin, showing the budding zone and fully formed zooids with and without ovicells; B, overview of non-ovicellate zooids, showing campanulate secondary orifices and paired lateral-suboral avicularia; C, close-up of non-ovicellate autozooid showing bipartite peristome and the paired avicularia; D, ovicellate zooid. Scalebars: A, 0.2 mm; B, C, D, 0.1 mm.