Chamberlainium capense 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 : 22-25

Chamberlainium capense Puckree-Padua, P.W. Gabrielson et Maneveldt sp. nov.

( Figures 4 , 7–11 , 12–14 , 15–18 ; Tables 1, 2).

Holotype: L 3986119 , 09.x.2016, leg. G. W. Maneveldt, collection number 16/05, epilithic on primary bedrock in mid-intertidal, sand inundated rock pool.

Type locality: South Africa, Western Cape Province, Mouille Point (33°53.9440′ S, 18°24.5285′ E) .

Etymology: ‘ capense ’ in reference to the species’ restricted distribution along the Cape Peninsula historically known as the ‘ Cape of Good Hope, South Africa’ (Caput Bonae Spei).

Description: Non-geniculate, thalli are moderately thick (up to 1000 µm), encrusting to mostly variably lumpy to slightly protuberant. Thalli are epilithic or epizoic and bright to dusky pink in well-lit conditions. Individual crusts do not appear to fuse together and are easily discernible. Thallus construction is monomerous with a single layer of epithallial cells. A central columella is present in tetrasporangial conceptacles that disintegrate to form a low mound with maturity. The pore opening in mature tetrasporangial conceptacles is occluded by a corona of filaments that projects above the opening. The psb A (851 bp) and rbc L (691–1387 bp) sequences are diagnostic.

Habitat: Thalli were epilithic on the primary bedrock and on large boulders in rock pools and on exposed platforms in the mid-intertidal zone, as well as epizoic on mollusc shells in the low intertidal zone.

Vegetative morphology and anatomy: Thalli were non-geniculate, moderately thick (up to 1000 μ m), encrusting (smooth) to mostly variably lumpy and slightly protuberant, with protuberances to 4 mm tall ( Figures 4 and 7, 8 ), and were firmly adherent, dusky pink to mauve (in well-lit conditions) to rosy or purple-pink (in dim light) when freshly collected ( Figure 4 ). Individual crusts did not fuse together and were easily discernible ( Figures 7, 8 ).

Thalli were dorsiventrally organized, monomerous and haustoria were absent. The medulla was thin and plumose (non-coaxial) ( Figures 9, 10 ). Medullary filaments comprised rectangular to elongate cells, which gave rise to cortical filaments that comprised mainly square to rectangular cells ( Figure 10 ). Contiguous medullary and cortical filaments were joined by cell fusions; secondary pit connections were absent ( Figure 10 ). Subepithallial initials (intercalary meristematic cells) were square to rectangular ( Figure 11 ). The epithallus was single layered with oval to rounded cells ( Figure 11 ). Trichocytes were common at the thallus surface and occurred singularly (mostly) to paired ( Figure 11 ). Trichocytes were always terminal and never intercalary in the cortex; buried 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 and raised above surrounding thallus surface ( Figures 12–14 ). Conceptacle chambers were transversely elliptical to flatten; conceptacle roof nearly twice as thick along pore canal ( Figures 13, 14 ). Conceptacle roof formed from filaments peripheral to the fertile area ( Figure 12 ). Throughout the early development, a protective layer of epithallial cells surrounded the conceptacle primordium ( Figure 12 ). This protective layer was shed once the pore canal was near fully developed. The pore opening was occluded by a mucilage plug ( Figures 13, 14 ). In mature conceptacles, terminal initials along 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 14 ). Unbranched (simple) spermatangial systems were confined to mature conceptacle floor ( Figures 12–14 ). Senescent male conceptacles appeared to be shed; no buried conceptacles were observed.

Tetrasporangial thalli were morphologically similar to spermatangial thalli. Conceptacles were uniporate, low domed and raised above the surrounding thallus surface ( Figures 15–17 ). Conceptacle chambers were transversely elliptical to bean-shaped. Conceptacle roof was nearly twice as thick along the pore canal and was 5–7 cells thick, including an epithallial cell. Pore canal tapered towards the surface, formed an arch ( Figure 18 ) and was lined by elongated papillate cells that projected into the canal and were orientated more or less parallel or nearly perpendicular to the conceptacle roof surface ( Figure 18 ). The roof was formed from filaments peripheral to the fertile area ( Figure 15 ) and terminal initials were more elongate than their inward derivatives. Throughout early development a protective layer of epithallial cells surrounded the conceptacle primordium ( Figure 15 ). This protective layer was shed once pore canal was near fully developed; the pore opening was occluded by a corona of filaments that projected above the pore opening ( Figures 16, 18 ). The corona appeared to form from filaments near the upper half of the roof, directly adjacent to the pore canal ( Figures 16, 18 ). Throughout the development of the tetrasporangial conceptacle, a prominent columella of sterile filaments formed at the center of the conceptacle chamber ( Figure 15 ), which extended into the pore canal ( Figure 16 ); the central columella appeared weakly calcified as with maturity it disintegrated to form a low mound ( Figure 17 ). The base of the pore canal was sunken into the chamber and terminal initials near the base pointed downward ( Figure 18 ). Mature conceptacle floors were sunken 11– 17 cells (including the epithallial cell) below the surrounding thallus surface. Zonately divided tetrasporangia were arranged at the extreme periphery of the conceptacle chamber and were attached via a stalk cell ( Figures 16, 17 ). Where the central columella had disintegrated or diminished, the tetrasporangia filled the chamber and appeared to be distributed across the chamber floor ( Figure 17 ). Senescent tetrasporangial conceptacles appeare 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 restricted distribution (± 43 km distance) along the southwest coast, from Mouille Point to Slangkop (Western Cape Province) along the Cape Peninsula, 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 7–11: ChamberlainiUm capenSe habit and vegetative anatomy. (7) Rock fragment showing holotype specimen (white arrow) (L 3986119, tetrasporangial). Scale bar = 20 mm. (8) Encrusting to variably lumpy and slightly protuberant, epilithic thalli showing crusts abutting and easily discernible. Scale bar = 10 mm. (9) 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 16/17). Scale bar = 50 μm. (10) Vertical section of the inner thallus showing cell fusions (f) between adjacent medullary filaments (UWC 16/17). Scale bar = 20 μm. (11) Vertical section of the outer thallus showing a single layer of epithallial cells (e) subtended by a layer of subepithallial initials (i). Note the paired, bottle-shaped trichocytes (t) (UWC 16/24). Scale bar = 20 μm.

Figures 12–14: ChamberlainiUm capenSe spermatangial anatomy (UWC 16/21). (12) Vertical section through the outer thallus showing a spermatangial conceptacle primordium with peripheral roof 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. (13) Vertical section through a mature, raised spermatangial conceptacle showing the mucilage plug (white arrowhead) that occludes the pore opening and simple, spermatangial systems (black arrowheads) confined to the conceptacle floor. Scale bar = 50 μm. (14) Magnified view through a mature spermatangial conceptacle showing the mucilage plug (white arrowhead) that occludes the pore opening and simple, spermatangial systems (black arrowheads) confined to the conceptacle floor. Note that the pore canal is lined with terminal,elongate initials (black arrows) that project into the pore canal as papillae. Scale bar = 20 μm.

Figures 15–18: ChamberlainiUm capenSe tetrasporangial anatomy. (15) Vertical section through the outer thallus showing a later stage tetrasporangial conceptacle primordium with peripheral roof development (black arrowheads) and tetrasporangial initials (t) arranged peripherally around a central columella (c). Note the persisting layer of protective epithallial cells (black arrow) (L 3986119).Scale bar = 50 μm. (16) Vertical section through a mature, raised tetrasporangial conceptacle showing tetrasporangia (t) with a stalk cell (black arrowhead), peripherally arranged around a well-defined central columella (C). Note the remains of a corona (white arrow) that surrounds the pore opening (L 3986119). Scale bar = 50 μm. (17) Vertical section through a mature raised tetrasporangial conceptacle showing tetrasporangia (t) with stalk cells (black arrowheads), appearing to be arranged across the chamber floor as the columella (c) has disintegrated. Note the absence of the corona (white arrow) (UWC 16/09). Scale bar = 50 μm. (18) Magnified view of the pore canal of a mature tetrasporangial conceptacle showing the base of the pore canal sunken (black arrowheads) into the chamber with terminal, elongate initials near the base pointing downward (black arrows) and the remains of a corona (white arrow) that surrounds and occludes the pore opening. (L 3986119). Scale bar = 20 μm.