Gibsmithia eilatensis Gabriel and Fredericq, 2016
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publication ID |
https://doi.org/ 10.11646/phytotaxa.277.1.1 |
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persistent identifier |
https://treatment.plazi.org/id/03ED87E3-1B5F-FFB8-FF30-6F74FA80FC58 |
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treatment provided by |
Felipe |
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scientific name |
Gibsmithia eilatensis Gabriel and Fredericq |
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sp. nov. |
Gibsmithia eilatensis Gabriel and Fredericq , sp. nov.
Figures 1A View FIGURE 1 , 4 View FIGURE 4 , 6–8 View FIGURE 6 View FIGURE 7 View FIGURE 8
HOLOTYPE:— ISRAEL. Red Sea : Eilat, Coral Beach, N 29 o 30 ’ 06” E 34 o 56’ 03”, 25 m depth, 24 July 2011, DG234, female gametophyte. Figs. 1A View FIGURE 1 , 4C View FIGURE 4 , 6A, T View FIGURE 6 . Sauvage and D. Gabriel, deposited in LAF. GoogleMaps
ISOTYPE:— ISRAEL. Red Sea: Eilat, Coral Beach, N 29 o 30’ 14” E 34 o 55’ 09”, 5 m depth, 22 July 2011, DG219, tetrasporophyte. Fig. 4A, T View FIGURE 4 . Sauvage and D. Gabriel, deposited in LAF.
ETYMOLOGY: The specific epithet refers to the type locality in the Red Sea. MATERIAL EXAMINED:— ISRAEL. Red Sea: Eilat, Coral Beach, DG 219 (tetrasporophyte) ; DG210 (female gametophyte); DG234 (female gametophyte); DG220 (male gametophyte). All specimens are deposited at LAF.
ECOLOGY: Plants growing individually, subtidally to 25 m depth, usually in cavities of coral colonies in reef environments. G. eilatensis was the only species of gelatinous red algae observed in the area during the collection period (mid-June to late July). Signs of herbivory or senescence were observed in specimen DG219.
GEOGRAPHIC DISTRIBUTION: G. eilatensis was collected all along the shores of Eilat in the Gulf of Aqaba (Red Sea) and its occurrence outside this area is unknown.
DESCRIPTION: Thalli of furry gelatinous clusters of unbranched to pseudodichotomously branched blush, pink to white lobes, with unbranched cartilaginous stalk, and round, dark to light pink holdfast. Medullary filaments abundant, colorless, of elongate cells subtending assimilatory filaments comprised of main percurrent filaments and straight cortical filaments comprised of 20–35 rectilinear to semispherical cells, sparingly branched laterals, and thin rhizoidal filaments growing thallus inwards, intertwined with medullary filaments. Seirospore filaments present. Plants dioecious, with isomorphic tetrasporophytes. Carpogonial branches borne along the middle portion of cortical filaments, straight, 5–(8–10)–15 cells long, with the terminal 5–7 cells modified; basal cells of carpogonial branches occasionally bearing short unbranched vegetative laterals; conical carpogonium cut off by oblique division, offcentered on large hypogynous cell; subhypogynous cell smaller and rounder than the cells flanking it; trichogyne straight, elongate; hypogynous cell in functional carpogonial branches extend laterally, producing a bulge. Auxiliary cell branch 13–(19–20)–24 cells long, with 3–(5)–7 modified cells, rounder than surrounding cells, darkly staining; basal 3–10 cells with unbranched filaments surrounding carposporangia; 4–12 terminal cells rectilinear, decreasing in size towards apex. Connecting filaments septate, often diploidizing multiple auxiliary cells (>5) nearby. Gonimoblast initials cut off from bulge at junction of outgoing connecting filament with auxiliary cell. Spermatangia borne radially on 3–(5)–6 terminal cortical cells, forming corncob-like structures; spermatangial heads borne in a similar position of tetrasporangia. Tetrasporangia sessile, isolated, usually borne on the adaxial side of percurrent filaments, terminal or lateral on short lateral branches, in patches along the upper part of gelatinous branches, 10–20 cells below the surface; tetrasporangia decussately to cruciately divided.
Habit and vegetative morphology. Thalli consist of furry, gelatinous clusters of unbranched to pseudodichotomously branched lobes ( Fig. 6 View FIGURE 6 ) that are predominantly blush in color ( Fig. 4 View FIGURE 4 ), occasionally pink to whitish ( Fig. 1A View FIGURE 1 ). Exserted cortical filaments from the lobes’ surface are prominently visible underwater ( Fig. 1A View FIGURE 1 ). The unbranched cartilaginous stalk ( Figs 4 View FIGURE 4 , 6A View FIGURE 6 ) is attached to the substratum by a round, dark to light pink holdfast. Cortical filaments are cut off alternately and sparingly from widely divergent main assimilatory filaments referred to as percurrent filaments and consist of rectilinear to spherical cells decreasing in size towards the surface (5–166.25) × (3.75–11.25) μm ( Figs 6B–C View FIGURE 6 ). Abundant colorless medullary cells are elongated and transition into distal assimilatory percurrent filaments ( Fig. 6C View FIGURE 6 ) whose cells measure 36.25–300 × 3.75–11.25 μm. Cells of lower cortical filaments cut off narrow rhizoidal filaments that connect to nearby rhizoidal cells ( Fig. 6B View FIGURE 6 ). Hair-like structures (6D) of variable length (12.5–120) × 1.25 μm occasionally extend from the apical cells of cortical filaments and staining darkly with aniline blue when short and become almost colorless when long. Rhizoidal filaments cut off from lower cortical cells grow thallus inward where they become intertwined with medullary filaments. Straight, small-celled, scarcely branched and unbranched seirospore filaments are present ( Fig. 6E View FIGURE 6 ) in tetrasporophytes.
Reproductive morphology. Thalli are dioecious, with isomorphic tetrasporophytes. Female pre-fertilization stages are scattered among elongated, narrow assimilatory filaments ( Fig. 6C View FIGURE 6 ). Carpogonial branches are formed laterally on assimilatory filaments, replacing normal vegetative filaments ( Figs 6F–G View FIGURE 6 ) in which the 5–9 upper cells transform into spherical cells while the subtending lower cells remain narrow and elliptic like other vegetative cells ( Figs 6F–6G View FIGURE 6 ). Transformed cells of the carpogonial filaments remain unbranched while the basal and lowermost untransformed cells may cut off short unbranched lateral cell strands growing distally and obliquely ( Figs 7A–B View FIGURE 7 ). The unfertilized carpogonium is conical with a long, straight trichogyne ( Figs 6F–G View FIGURE 6 , 7A–B View FIGURE 7 ), separated by an oblique division from the hypogynous cell. The hypogynous cell extends laterally and obliquely ( Figs 6F–G View FIGURE 6 ). The subelliptical subhypogynous cell is very small ( Figs 6F–G View FIGURE 6 , 7A View FIGURE 7 ), with the cell subtending it the largest cell of the carpogonial branch. Auxiliary cell filaments ( Fig. 7C View FIGURE 7 ) are homologous in position and origin to the carpogonial branches and cortical filaments. Three to seven transformed intercalary cells of an auxiliary cell filaments ( Figs 7C–E View FIGURE 7 ) become darkly staining, enlarged and roundish, and flank below and above an auxiliary cell that remains small, cytoplasm-poor and colorless ( Figs 7D–F View FIGURE 7 ). Some of these dark cells or untransformed cells below bear unbranched laterals growing distally and obliquely ( Fig. 7C View FIGURE 7 ). After presumed fertilization, the carpogonium produces a lateral extension that follows the orientation of the expanding hypogynous cell ( Figs 7A–7B View FIGURE 7 ). Upon reaching an auxiliary cell, an unsegmented, hyaline incoming connecting filament connects laterally to the upper side of the auxiliary cell ( Fig. 7D View FIGURE 7 ). It is assumed that during this process a product of the fertilization nucleus is transferred from the connecting filament to the auxiliary cell. Following this diploidization of an auxiliary cell, the incoming connecting filament continues to grow as an outgoing connecting filament ( Fig. 7D View FIGURE 7 ). When reaching another auxiliary cell, the former outgoing filament acts as a new incoming filament, developing cross walls at the site of a new diploidization ( Fig. 7E View FIGURE 7 ) that leads to the formation of a short segment that partly fuses with the auxiliary cell and then continues as an outgoing connecting filament ( Fig. 7E View FIGURE 7 ). A single roundish gonimoblast initial ( Figs 7E–F View FIGURE 7 ) is cut off from the short segment formed on the point of contact between the auxiliary cell and the connecting filament. The outgoing connecting filament continues to reach nearby auxiliary cells and before reaching a new auxiliary cell develops a cross wall, forms a short segment that contains part of the divided fertilization nucleus which fuses with the auxiliary cell ( Figs 7E–F View FIGURE 7 ). Following the formation of the first gonimoblast initial, the fertilization nucleus in the generative segment cuts off additional gonimoblast cells that each will continue to divide laterally and radially resulting in small clusters of cells ( Figs 7G–H View FIGURE 7 ). The issuing of a connecting filament primordium from the carpogonium was only observed once ( Fig. 7B View FIGURE 7 ), prior to its fusion with the hypogynous cell and cells below the subhypogynous cell. Mature auxiliary cell branches are 13–(19–20)–24 cells long ( Figs 7C–H View FIGURE 7 ). The lowermost 3–10 cells of the auxiliary cell filament typically cut off short-celled unbranched vegetative filaments that surround the gonimoblast cells (7G–H) as they mature into carposporangia. The upper 4–12 terminal cells of the auxiliary cell filament are rectilinear, decreasing in size toward the apex ( Figs 7C, 7E, 7H View FIGURE 7 ). Gonimoblast cells resulting from a single diploidization event mature gradually in a synchronized fashion, resulting in same-sized cells ( Fig. 7H View FIGURE 7 ). Mature carposporophytes were not observed.
Young clusters of spermatangia are formed on terminal and lateral cells of assimilatory cortical filaments on dioecious gametophytes ( Fig. 7I View FIGURE 7 ). The spermatangial initials are cut off radially as multiple small protrusions on 3–(5)–6 consecutive cells in a single filament. When the lateral cell filament is 7 cells long, the 6–celled spermatangial branch is pedicellate ( Figs 8A–B View FIGURE 8 ); if 6 cells long the corncob-like structure is sessile, and if more than 6 cells long, the male reproductive structure is terminally positioned on a lateral branch ( Fig. 7I View FIGURE 7 ). Mature spermatangial heads, 25–(50–81.25) × 11.25(15–18.75) μm ( Figs 8A–B View FIGURE 8 ), are oblong and borne in a similar position as the tetrasporangia on cortical filaments. Spermatangia are abundant, measuring (2–2.5) × (1.5–2) μm ( Fig. 8B View FIGURE 8 ).
Tetrasporangial initials ( Figs 8C–D View FIGURE 8 ) are cut off unilaterally in short series either obliquely from the upper side of cells on short laterals on cortical filaments, or are terminal on these short laterals in the upper part of the gelatinous branches. Tetrasporangia are usually decussately divided ( Fig. 8E View FIGURE 8 ), sometimes cruciate ( Fig. 8C View FIGURE 8 ), (15–18.75) × (11.25– 13.75) μm.
NOTE: The present description was based on a small number of samples found after extensive searches along the coast of Eilat. Although all three life history phases were observed for G. eilatensis , connecting filament formation and mature cystocarps were not observed in our extensive squash preparations. Unlike those of G. hawaiiensis , cortical filaments in G. eilatensis are rarely cut off oppositely from the main percurrent filaments and are usually unbranched or sparingly alternately branched ( Table 2). Seirospores are found in chains as in G. hawaiiensis , but occasionally present short branchlets. Carpogonial branches bear an enlarged hypogynous cell and a very small subhypogynous cell, while all cells of the carpogonial branch are similar in size and shape in G. hawaiiensis . Auxiliary cell branches are also composed of similarly shaped modified cells in G. hawaiiensis , while auxiliary cell is smaller in G. eilatensis . The origin of the gonimoblast initials is from the point of junction between the connecting filament and the auxiliary cell, contrasting with the generitype, where gonimoblasts are initiated from the auxiliary cell. Tetrasporangia are mostly borne on short lateral branches on inner cells of cortical filaments, while in G. hawaiiensis they have a 2–3-celled pedicel.
REPRESENTATIVE SEQUENCES: KM406844 (COI-5P), KM392352 (rbc L) and KM392317 (UPA).
| LAF |
University of Louisiana at Lafayette |
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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