Gelidiella papillosa Núñez-Resendiz, Dreckmann et Sentíes, 2023

Resendiz, María Luisa Núñez, Sentíes, Abel, Dreckmann, Kurt M., Hernández, Oscar E. & Vilchis, Martha Isabel, 2023, Gelidiella papillosa sp. nov. (Gelidiellaceae, Rhodophyta) from Veracruz, Mexico, in the context of the worldwide distribution of G. acerosa, Botanica Marina (Warsaw, Poland) 66 (6), pp. 521-533 : 526-527

Gelidiella papillosa Núñez-Resendiz, Dreckmann et Sentíes sp. nov. ( Figures 3 – 8 and 9 – 17 ).

Description: Thalli forming tufts, yellow to dark red; erect axes arising from creeping axes attached by unicellular rhizoids to the substratum, 2.5 – 4.5 (−6) cm long and 600 – 700 µm in diameter, branching distichous or rarely radial; branchlets lanceolate, 0.5 – 2 mm long and 250 – 275 µm in diameter, alternately opposite, with numerous superficial hyaline hairs; papillose bumps numerous, arranged radially at base of axes and branches, 290 – 350 µm in length and 200 – 240 µm in diameter, depressed apically; inner cortex with 2 – 3 cell layers, 5 – 6 µm in length and 2.5 – 4 µm in diameter, outer cortex with 2 cell layers, 4 – 7.5 µm in length and 10 µm in diameter; medullary cells with thick walls, 4.5 – 5 µm in length and 7.5 – 12 µm in diameter; 3 – 12 apical stichidia per fertile branch, 1 – 1.5 mm in length and 325 × 475 µm in diameter; tetrasporangia tetrahedrally divided, 35 – 40 µm in length and 20 – 25 µm diameter.

Type locality: 19°35.22 ′ N, 96°22.43 ′ W; Morro de la Mancha, Veracruz, Mexico .

Holotype designated here: UAMIZ-1432, tetrasporophyte ( Figure 3 ), collected 01 July 2015 by Abel SentÍes, deposited in the Metropolitan Herbarium UAMIZ. GenBank Accession number for COI-5 P: MN190015 and rbc L: MN190010 .

Paratype: UAMIZ-1438, tetrasporophyte, collected 10 May 2020 by M . L . Núñez Resendiz, & Abel SentÍes ( UAMIZ).

Etymology: The specific epithet ( papillosa = having papillae) refers to the presence of numerous small papillae at the bases of the main axes and branches.

Thalli were forming tufts, yellow to dark red in color, cartilaginous, rough, non-lubricated ( Figures 3 and 4 ), differentiated into a decumbent axis, fixed to the substratum by groups of unicellular rhizoids, from which numerous branched erect axes arose ( Figure 5 ). Erect axes were cylindrical to slightly compressed, 2.5 – 4.5 (−6) cm in length and 600 – 700 µm in diameter ( Figure 6 ), branching profusely distichous or rarely radial. Branchlets were lanceolate, with acute tips, 0.5 – 2 mm in length and 250 – 275 µm in diameter, cylindrical, arranged alternately opposite ( Figure 5 ), slightly curved and covered by numerous unicellular hyaline hairs over the entire surface ( Figure 7 ). Erect axes and branches were growing by a prominent dome-shaped apical cell ( Figure 8 ), apices notoriously darkened ( Figure 9 ). Numerous warty bumps arose on the basal portions of erect axes and branches ( Figure 10 ), small, papilla-shaped, radially arranged in axes, 130 – 150 µm in length and 180 – 200 µm in diameter, apically depressed ( Figure 11 ), some had blunt apices ( Figure 12 ), no apparent apical cell was observed as in the case of axes and main branches. In cross section, cortex was made up of 2 – 3 layers of outer cortical cells, elongated, pigmented, 5 – 6 µm in length and 2.5 – 4 µm in diameter, and 2 layers of inner cortex cells, 4 – 7.5 µm in length and 10 µm in diameter ( Figure 13 ); medulla was made up of oval or irregular cells with thick walls, 4.5 – 5 µm in length and 7.5 – 12 µm in diameter ( Figure 13 ).

Gametophytes were not seen. Tetrasporangia were in swollen stalked stichidia, arranged in the apical portions of terminal branches, 3 – 12 per fertile branch ( Figure 14 ), compressed, 1 – 1.5 mm in length, and 325 × 475 µm in diameter. Tetrasporangia were embedded in cortical layer ( Figure 15 ), arising laterally from an inner cortical cell ( Figure 16 ), tetrahedrally divided when mature ( Figure 17 ), elongated, 35 – 40 µm in length and 20 – 25 µm diameter.

Habitat: Plants growing on rocky platforms exposed directly to the waves, on the surface or in tide pools, in the intertidal zone, between 0.5 and 1 m deep, exposed to direct light at low tide hours, present throughout the year although they are more abundant in the months of March to August; in association with species of Laurencia J.V. Lamouroux and Acanthophora J.V. Lamouroux.

Figures

Figures 3–8: Gelidiella papillosa sp. nov. (3) Holotype specimen, tetrasporic plant. UAMIZ-1432.Scale bar = 1 cm. (4) UAMIZ-1435. Fresh specimen of tetrasporic plant showing general appearance of the thallus. Scale bar = 5 mm. (5) UAMIZ-1437. Vegetative plant showing branching pattern in erect axes arising from a decumbent stolon. Scale bar = 1 cm. (6) UAMIZ-1437. Cross section through middle part of an erect axis. Scale bar = 130 µm. (7) UAMIZ-1432.Tip of branchlet showing numerous superficial cortical hairs (arrows). Scale bar = 700 µm. (8) UAMIZ-1432. Detail of young branchlet showing apical cell (arrow). Scale bar = 200 µm.

Figures 9–17: Gelidiella papillosa sp. nov. (9) UAMIZ-1438. Detail of main axis and branchlets showing darkened tips. Scale bar = 3 mm. (10) UAMIZ-1433. Fresh specimen showing detail of basal region of main axis with papillose bumps (arrows). Inset, enlargement of a bump. Scale bar = 1.5 mm. (11) UAMIZ-1432.Cross section of basal portion of main axis showing a papilla with depressed apex (arrow). Scale bar = 130 µm. (12) UAMIZ-1436. Cross section of basal portion of main axis showing development of papilla without evident apical cell, with blunt apex. Scale bar = 66 μm. (13) UAMIZ-1437. Cross section of main axis showing outer cortical cells (arrowheads), inner cortical cells (blue arrows) and medullary cells (black arrows). Scale bar = 15 µm. (14) UAMIZ-1433. Detail of fertile branch showing swollen stichidia at apices of branchlets (arrows). Scale bar = 1 mm. (15) UAMIZ-1432. Cross section through middle portion of fertile branchlet showing arrangement of tetrasporangia (arrows). Scale bar = 110 µm. (16) UAMIZ-1433. Cross section of fertile branchlet showing immature tetrasporangia arising from inner cortical cells (arrows) and premature development of tetrasporangia (arrowheads). Scale bar = 30 µm. (17) UAMIZ-1432. Cross section through middle portion of fertile branchlet showing mature tetrasporangia. Scale bar = 30 µm.