Exidmonea intercalata, Liu & Liu & Zágoršek, 2019

Liu, H., Liu, X. & Zágoršek, K., 2019, Cyclostome bryozoans from Qingdao, South Yellow Sea, China, Zootaxa 4603 (3), pp. 473-500 : 480-481

Exidmonea intercalata n. sp.

( Figs 16–21 )

lsid:zoobank.org:act: E7C19B17-7B70-45A6-989B-DCC1004FD20D

Diagnosis. Exidmonea with 2–6 autozooidal tubes in each fascicle, gonozooid situated at bifurcation, with ooeciopore located on its distalmost edge, downwardly curved, swan-neck shaped, hidden/immersed between bifurcating branches.

Holotype. Specimen MBM 284444 from Lingshan Island ( Figs 16–18 ).

Paratypes. Specimens MBM 284469 , MBM 284470 , MBM 284472 , MBM 284376 ( Jiaozhou Bay) and MBM 284499 ( Jiaozhou Bay) .

Additional material. More than 10 colonies from samples MBM 0 92370, MBM 194661 (Lingshan Island), MBM 0 92378 ( Jiaozhou Bay) and MBM 0 91767 ( Jiaozhou Bay)

Etymology. Referring to the immersed/submerged ooeciostome in the zone of bifurcation.

Description. Colony erect, dichotomously branched. Branches short (the distance between successive bifurcations approximately 880–1380 µm) and narrow (430–500 µm wide before bifurcation). Approximately 6–8 autozooidal fascicles between successive branch bifurcations. Fascicles alternating, each consisting of 2–6 autozooidal apertures. Distance between fascicles in the longitudinal direction ca. 210–300 µm. Apertures oval to rounded rectangular, diameter approximately 90–110 µm. Gonozooid triangular, small (ca. 410–460 µm wide by 500–520 µm long), situated frontally in the zone of bifurcation, spreading over two or three fascicles, with densely porous frontal wall (pseudopore diameter ca. 8–10 µm). Ooeciopore located on the distalmost edge of the gonozooid, hidden between bifurcating branches, narrower than autozooidal tubes (ca. 60 µm wide). Ooeciostome short, downwardly curved, swan-neck shaped, adjacent to a deformed autozooidal tube with elongated oval aperture. Dorsal side of the colony flat, with arcuate growth lines and pseudopores arranged parallel to them; kenozooids absent.

Remarks. Idmonea pauper Canu & Bassler (1929 , p. 545, pl. 84, figs 13, 14) is similar to the new species in the size and position of gonozooid, but differs in having ooeciopore adjacent to the first peristome of a fascicle.

The downwardly curved, swan-neck shaped ooeciostome of the new species is similar to that of Idmidronea atlantica (Forbes in Johnston, 1847) , as described by Hayward & Ryland (1985). However, I. atlantica differs mainly in having much denser fascicles and longer branches (more than 20 fascicles between successive bifurcation and the branch is more than 4 mm long). Moreover, I. atlantica develops a kenozooidal overgrowth on the dorsal side of the branches.

Occurrence. Jiaozhou Bay and Lingshan Island.

Figures

FIGURES 16–21. Exidmonea intercalata n. sp. Lingshan Island. 16–18. Holotype MBM 284444 from Lingshan Island. 16. General view showing the position of gonozooids. 17. Detail of the gonozooid situated at bifurcation. 18. Detail of the ooeciopore hidden between bifurcating branches and forming a down-curved, swan-neck shape. 19. Paratype MBM 284470, showing the position of the gonozooid and cross-section of the triangular branch. 20. Dorsal side of specimens MBM 284469, showing circular pseudopores. 21. Paratype MBM 284470, detail of the ooeciopore. Scale bars: 16 = 1 mm; 17–21 = 100 µm.