Meristotheca spinella Núñez-Resendiz, Dreckmann & Sentíes, 2019

Núñez-Resendiz, María Luisa, Dreckmann, Kurt M., Sentíes, Abel & León-Tejera, Hilda P., 2019, Meristotheca spinella Núñez-Resendiz, Dreckmann & Sentíes, sp. nov. (Solieriaceae, Rhodophyta) a new cylindrical species from the southwestern Gulf of Mexico, Cryptogamie, Algologie 20 (6), pp. 63-72 : 65-67

Meristotheca spinella Núñez-Resendiz, Dreckmann & Sentíes , sp. nov.

( Figs 2 , 3 )

HOLOTYPE. — UAMIZ-1332 ( Fig. 2A ), tetrasporophyte, collected at Bahia Tortuga (19.2135°N, 90.4235°W), Campeche ( Mexico), on 06.VI.2015, collected by M. L. Núñez & K. M. Dreckmann. GenBank accession number MK135825 .

ISOTYPE. — UAMIZ-1331, tetrasporophyte, collected at Bahia Tortuga, Campeche ( Mexico), on 06. VI.2015, collected by M. L. Núñez & K. M. Dreckmann. GenBank accession number MK 135823 .

PARATYPES. — Listed in Table 1.

ETYMOLOGY. — The specific epithet spinella refers to the numerous short branches or spine-shaped proliferations that completely cover the margins of the main axes and branches.

DIAGNOSIS. — Thalli 20−35 cm high, terete, dark red in color, attached by a discoid holdfast, branching dichotomously, alternately, opposite or laterally, primary axes 1250-1500 µm in diameter; branches 550-750 µm in diameter, covered with small spine-shaped branchlets. Narrow medullary filaments with numerous single-celled rhizoids, 2.5-4 µm in diameter. Inner cortex with five to six layers of cells, 25-45 µm × 20−30 µm in diameter, with small connective filaments. Outer cortex with four to five layers of cells, 10-45 µm long and 4-14 µm in diameter. Tetrasporangia claviform, 20-30 µm long and 4-7 µm in diameter, basally anchored by an elongated supporting cell that can form 3-celled cortical filaments, 7-10 µm long and 4-6 µm in diameter. Cystocarps ellipsoidal, 600-650 µm long and 320-430 µm in width.

ECOLOGY. — Populations of Meristotheca spinella Núñez-Resendiz, Dreckmann & Sentíes , sp. nov. were found throughout the year, with greater abundance during the spring (tetrasporophytic state) and summer (vegetative state). They were growing in sandy environments of turbid waters, with little exposure to light, attached to rocky substrata (1-1.5 m deep). They were part of the algal canopy of the submerged algal community together with different species of large red algae, such as Alsidium seaforthii (Turner) J.Agardh , Crassiphycus corneus (J.Agardh) Gurgel, J.N.Norris & Fredericq, C. usneoides (C.Agardh) Gurgel, J.N.Norris & Fredericq, Eucheumatopsis isiformis , Meristotheca cylindrica , and Tepoztequiella rhizoidea , which were as abundant as M. spinella Núñez-Resendiz, Dreckmann & Sentíes , sp. nov. It was also a conspicuous component of the algal drift at the end of summer.

Figures

FIG. 2. — Meristotheca spinella Núñez-Resendiz, Dreckmann & Sentíes, sp. nov: A, Holotype specimen; tetrasporic plant; B, Cystocarpic plant with numerous spines and short laterals; C, Habit of a vegetative plant; D, Vegetative plant with abundant branches and spines. Scale bars: A, 3 cm; B, 2 cm; C, D, 4 cm.

FIG. 3. Meristotheca spinella Núñez-Resendiz, Dreckmann & Sentíes, sp. nov.: A, cross section showing a filamentous medulla (arrow) surrounded by cortical cells (white arrow); B, Longitudinal section showing medullary filaments (arrow) running parallel to the main axes and cortical cells; C, Medullary filaments with numerous rhizoids (arrows); D, Inner cortical cells interconnected by small cortical connective filaments (arrow) and secondary pit connections (white arrow); E, Outer cortical cells interconnected by primary pit connections (arrows); F, Tetrasporangia arising from outer cortical cells; G, Tetrasporangia arising from a four-celled cortical filament (arrow); H, Branch with short laterals bearing cystocarps (arrows); I, Nutritive cell clusters formed from vegetative cells around the diploidized auxiliary cell (white arrows); J, Mature cystocarp arising from medullary filaments cells: auxiliary cell (arrow) and enveloping tissue (white arrows); K, Mature cystocarp showing the pericarp (white arrows), sterile gonimoblast cells (gc), and chains of carpospores (cp). Scale bars: A, B, 150 µm; C, 70 µm; D, 100 µm; E, I, 60 µm; F, 80 µm; G, 40 µm; H, 3 mm; J, K, 250 µm.