Chamberlainium glebosum Puckree-Padua, P.W. Gabrielson et Maneveldt, 2021

Puckree-Padua, Courtney A., Gabrielson, Paul W. & Maneveldt, Gavin W., 2021, DNA sequencing reveals three new species of Chamberlainium (Corallinales, Rhodophyta) from South Africa, all formerly passing under Spongites yendoi, Botanica Marina (Warsaw, Poland) 64 (1), pp. 19-40 : 25-30

Chamberlainium glebosum Puckree-Padua, P.W. Gabrielson et Maneveldt sp. nov. ( Figures 5 , 19–23 , 24–25 , 26–30 ; Tables 1, 2).

Holotype: L 3986123 , 17vii.2015, leg. G. W. Maneveldt, collection number 18/05, epilithic on primary bedrock in a mid-intertidal rock pool.

Type locality: South Africa, Western Cape Province, Melkbosstrand (33°44.2518′ S, 18°26.1343′ E) .

Etymology: ‘ glebosum ’ from ‘ glebosus ’, making reference to the species’ lumpy ( Stearn 1973) and highly protuberant growth form.

Description: Non-geniculate, thalli are thick (to 2000 µm), very lumpy becoming highly protuberant. Thalli are epilithic and brownish pink to gray in well-lit conditions. Individual crusts do not appear to coalesce (do not fuse together) and are easily discernible. The thallus construction is monomerous with a single layer of epithallial cells. A central columella is present in tetrasporangial conceptacles, which disintegrates to form a low mound with maturity. The pore opening in mature tetrasporangial conceptacles is unoccluded. The psb A (851 bp) and rbc L (691–1387 bp) gene sequences are diagnostic.

Habitat: Thalli were epilithic on the primary bedrock in the high and mid-intertidal zones and only occasionally on the low shore.

Vegetative morphology and anatomy: Thalli were non-geniculate, thick (up to 2000 μ m), very lumpy becoming highly protuberant with protuberances to 6 mm tall ( Figures 5 , 19 and 20 ), and were firmly adherent, mostly brownish pink to greyish when freshly collected ( Figure 5 ). Individual crusts did not coalesce (did not fuse together) and were easily discernible ( Figure 5 ).

Thalli were dorsiventrally organized, monomerous and haustoria were absent. The medulla was thin and plumose (non-coaxial) ( Figures 21, 22 ). Medullary filaments comprised rectangular to elongate cells, which gave rise to cortical filaments that comprised square to rectangular cells ( Figures 22, 23 ). Contiguous medullary and cortical filaments were joined by cell fusions; secondary pit connections were absent ( Figures 22, 23 ). Subepithallial initials (intercalary meristematic cells) were square to rectangular ( Figure 23 ). The epithallus was single layered with rounded to elliptical cells ( Figure 23 ). Trichocytes were not observed. Data on morphological and measured vegetative characters are summarized in Table 1.

Reproductive morphology and anatomy: Gametangial thalli appeared to be dioecious, although female plants were not observed.

Spermatangial (male) conceptacles were uniporate, low-domed, raised above surrounding thallus surface ( Figures 24, 25 ). Conceptacle chambers were transversely elliptical to flatten with the roof nearly twice as thick along the pore canal ( Figure 25 ). The roof was formed from filaments peripheral to the fertile area ( Figure 24 ). Throughout the early development, a protective layer of epithallial cells surrounded the conceptacle primordium ( Figure 24 ). This protective layer was shed once the pore canal was near fully developed. The pore opening was occluded by a mucilage plug ( Figure 25 ). In mature conceptacles the terminal initials along the pore canal were enlarged and papillate, they projected into the pore canal and were orientated more or less parallel to the conceptacle roof surface ( Figure 25 ). Unbranched (simple) spermatangial systems were confined to floor of mature conceptacle ( Figures 24, 25 ). Senescent male conceptacles appeared to be shed as no buried conceptacles were observed.

Tetrasporangial thalli were morphologically similar to spermatangial thalli. Conceptacles were uniporate, low domed and raised above surrounding the thallus surface ( Figures 26–29 ). Conceptacle chambers were transversely elliptical to bean-shaped. The roof was nearly twice as thick along the pore canal and were 4–8 (9) cells (including an epithallial cell) thick ( Figure 29 ). The pore canal tapered towards the surface was lined by elongated papillate cells that projected into the pore canal and were orientated more or less parallel or nearly perpendicular to the conceptacle roof surface ( Figure 30 ). The roof was formed from filaments peripheral to the fertile area ( Figures 26–28 ) and terminal initials were more elongate than their inward derivatives ( Figure 27 ). Throughout the early development a protective layer of epithallial cells surrounded the conceptacle primordium ( Figures 26–28 ). This protective layer was shed once the pore canal was near fully developed. The pore opening in mature conceptacles was unoccluded ( Figures 29, 30 ). Throughout the development of the immature tetrasporangial conceptacle, a prominent columella of sterile filaments formed at the center of the conceptacle chamber ( Figures 27, 28 ), which extended into the pore canal ( Figure 29 ); the central columella appeared weakly calcified as with maturity it disintegrated to form a low mound. The base of the pore canal was sunken into the chamber and terminal initials near the base pointed downward ( Figures 29, 30 ). Mature conceptacle floors were sunken 11–24 cells (including the epithallial cell) below the surrounding thallus surface. Zonately divided tetrasporangia at maturity were arranged at the extreme periphery of conceptacle chamber and was attached via a stalk cell ( Figure 29 ). Senescent tetrasporangial conceptacles appeared to be shed as no buried conceptacles were observed. Data on reproductive characters are summarized in Table 2.

Distribution: Confirmed by DNA sequences to have a wide, but disjunct distribution along the west coast, occurring from Port Nolloth to Groenriviermond (Northern Cape Province, ± 220 km distance) and then from Cape St. Martin to Slangkop (Western Cape Province, ± 200 km distance), South Africa.

Figures

Figures 4–6: Habit photographs of ChamberlainiUm capenSe, C. gleboSUm and C. occidentale. (4) ChamberlainiUm capenSe is moderately thick to mostly lumpy and only slightly protuberant. Scale bar = 20 mm. (5) ChamberlainiUm gleboSUm is thick, very lumpy and highly protuberant. Scale bar = 20 mm. (6) ChamberlainiUm occidentale is morphologically highly variable, occurring as thin encrusting (smooth) to thick warty (mostly) to lumpy plants, and are only slightly protuberant. Scale bar = 30 mm.

Figures 19–23: ChamberlainiUm gleboSUm habit and vegetative anatomy. (19) Rock fragment with holotype specimen showing the region (white arrow) of the holotype from which all analyses were done (L 3986123, tetrasporangial). Scale bar = 20 mm. (20) Magnified view showing highly protuberant nature of C. gleboSUm holotype specimen (L 3986123). Scale bar = 2 mm. (21) Vertical section through the margin (black arrow) showing the monomerous thallus construction with plumose medulla (M) giving rise to cortical filaments (C) that terminate in a single layer of epithallial cells (black arrowhead) (UWC 15/34). Scale bar = 100 μm. (22) Vertical section of the inner thallus showing cell fusions (f) between adjacent medullary filaments (UWC 15/34). Scale bar = 10 μm. (23) Vertical section of the outer thallus showing a single layer of epithallial cells (e) subtended by a layer of subepithallial initials (i). Note the cell fusions (f) between adjacent cortical filaments (UWC 15/34). Scale bar = 20 μm.

Figures 24–25: Vertical section through the outer thallus showing spermatangial conceptacle primordium with peripheralroof development (black arrows) and simple spermatangial systems (black arrowheads) confined to the conceptacle floor. Note the protective layer of epithallial cells (white arrow). Scale bar = 50 μm. Vertical section through the outer thallus showing a mature, raised spermatangial conceptacle with the mucilage plug (white arrow) that occludes thepore opening andsimple,spermatangial systems (white arrowheads) confined to the conceptacle floor.Note that the pore canal is lined with terminal, elongate initials (black arrowheads) that project into the pore canal as papillae. Scale bar = 50 μm.

Figures 26–30: ChamberlainiUm gleboSUm tetrasporangial anatomy. (26) Vertical section through the outer thallus showing an early stage tetrasporangial conceptacle primordium with peripherally arranged tetrasporangial initials (black arrowheads) and a protective layer of epithallial cells (black arrow) (UWC 15/17). Scale bar = 50 μm. (27) Vertical section through the outer thallus showing a later stage tetrasporangial conceptacle primordium with peripheral roof development (black arrowheads) with a developing central columella (white arrowhead). Note the persisting layer of protective epithallial cells (black arrow) (UWC 15/17). Scale bar = 50 μm. (28) Vertical section through a maturing tetrasporangial conceptacle showing tetrasporangial initials (t) arranged peripherally around a central columella (between white arrowheads). Note the layer of protective epithallial cells (black arrow) being shed (L 3986123).Scale bar = 50 μm. (29) Vertical section through a mature, raised tetrasporangial conceptacle showing tetrasporangia (t) with stalk cells (white arrowheads), peripherally arranged around a well-defined central columella (C). Note the base of the pore canal sunken into the chamber with terminal, elongate initials near the base pointing downward (black arrowheads) (UWC 15/55). Scale bar = 100 μm. (30) Magnified view of the pore canal of a mature tetrasporangial conceptacle showing terminal, elongate initials (black arrows) that project into the pore canal as papillae and the base of the pore canal sunken (black arrowheads) into the chamber with terminal, elongate initials near the base pointing downward (UWC 15/55).Scale bar = 20 μm.