Hydropuntia

Gurgel, Carlos Frederico D., Norris, James N., Schmidt, William E., Le, Hau Nhu & Fredericq, Suzanne, 2018, Systematics of the Gracilariales (Rhodophyta) including new subfamilies, tribes, subgenera, and two new genera, Agarophyton gen. nov. and Crassa gen. nov., Phytotaxa 374 (1), pp. 1-23 : 9-10

Hydropuntia subgenus Polycavernosa (C.F. Chang et B.-M. Xia) Gurgel, J.N.Norris et Fredericq, stat. et subgen. nov.

TYPE: Polycavernosa C.F. Chang et B.- M. Xia 1963: 120.

TYPE SPECIES: Polycavernosa fastigiata C.F. Chang et B.- M. Xia 1963: 120, pl. I: figs.1–12; pl. II: figs. 1–6. HOLOTYPE: AST 60- 7240. Note: now Hydropuntia edulis (S.G. Gmelin) Gurgel et Fredericq 2004: 155 , basionym: Fucus edulis S.G.Gmelin, 1763: 113 .

TYPE LOCALITY: Yinggehai, SE end of Hainan Island, Hainan Province, South China Sea, China.

PERTINENT SYNONYM: Hydropuntia fastigiata ( C. F.Chang et B.- M.Xia) M. J. Wynne 1989: 477.

DESCRIPTION: Thalli erect, attached by a rhizomatous base, terete throughout, branching without constriction at bases of branches, highest order branches usually bifid, tapered gradually to acute tips. Gonimoblast cells ovoid to fusiform, forming a spherical central mass; tubular nutritive cells issued only from gonimoblast base and fusing with cells of the inner pericarp, these in turn uniting to form a network of darkly staining stellate fusion cells; innermost cells of the pericarp not stretching during cystocarp development. Spermatangial conceptacles of the medullary type, protruding slightly from the surface at maturity; young conceptacles embedded in cortex and medulla, multicavitied, the cavities separated by thin layers of wall material, with a single opening formed above the level of the surface cortical cells, probably by the rupture of an outer cuticle; cavities enlarging in all directions displacing neighboring cortical cells and compressing them while maintaining their pit connections, sometimes surrounding a cortical cell during enlargement; breakdown of cross walls between globular portions of multi-cavitied conceptacles sometimes resulting in a single large-lobed conceptacle; spermatangia cut off inwardly into conceptacle cavity from spermatangial parent cells. Tetrasporangia subspherical, cruciately divided, slightly protruding with flattened or elongated cells present adjacent to the tetrasporangium.

REMARKS: The gonimoblast mass (placenta) in H. sect. Polycavernosa is not spherical, but characterized by a lobed morphology, and the inner gonimoblasts are usually composed of rounder and smaller cells compared to those in the genus Crassa .

PERTINENT SPECIES IN SUBGENUS POLYCAVERNOSA : Hydropuntia edulis (S.G. Gmelin) Gurgel et Fredericq ; H. preissiana (Sonder) Gurgel et Fredericq ; H. rangiferina (Kützing) Gurgel et Fredericq ; and H. perplexa (K.Byrne et Zuccarello) Conklin in Conklin et al. (2014), plus the following species based on other published studies or unpublished data: