Desikachary, T.V.

Pacific Science

ScholarSpace at University of Hawai'i at Manoa

Observations on Two Species of Liagora (Rhodophyta) 1 T. V. DESIKACHARy2 ALTHOUGH THE ONTOGENY of the cystocarp has been studied in a number of species of the nemalionalean genus Liagora (Butters, 1911; Bl1lrgesen, 1915-20, 1927; Kylin, 1930; Ya-mada, 1938; Levring, 1941; Abbott. 1945), gaps still exist in our knowledge of the de-velopment of this structure. Thus, little pre-cise information is at hand concerning the place of origin of the so-called involucral filaments and as regards the presence or ab-,ence of a fusion-cell in the mature cystocarp }f certain species (see Papenfuss, 1946: 433, 434). The present account is based upon a ,tudy of two Hawaiian species, L. maxima Butters and L. Papenfussii Abbott, material of which was kitl.dly placed at the disposal of the writer by Professor Papenfuss. LIAGORA MAXIMA Described by Butters (1911) from the Ha-waiian Islands, this species was again reported by Abbott (1945). The material studied by the writer was collected by Papenfuss on the Island of Oahu (1.8 miles west of Nanakuli) on May 16, 1941. STRUCTURE OF THALLUS: The general habit and structure of Liagora maxima have been well described by both Butters and Abbott. Although the thallus varies greatly in length, some specimens may attain a height of as much as 40 cm., which marks this species as one of the largest in the genus. The plants are very much calcified. The main branches arise at or near the base and constitute per-1 This study was carried out during the tenure of a Fulbright award, for which the writer is very grateful. Thanks are due Professor George F. Papenfuss of the University of California, Berkeley, for his kind guid-ance during the investigation. Manuscript received November 22, 1955. 2 Department of Botany, U ni lersity of Saugar, Sagar (M.P.) , India. 423 current axes from which issue branches of limited growth. The main axes and their branches are composed of a central core of compact, vertical filaments (the medulla) from which are produced radially directed assimilatory laterals (the cortex). The lateral filaments are repeatedly dichotomously branched-up to the sixth order (Fig. 1a). The length of the cells of these filaments and the distance between the dichotomies gradu-ally diminish toward the surface of the thallus. In younger parts the assimilatory filaments often terminate in long hairs. ' REPRODUCTION: Liagora maxima is dioeci-ous. The spermatangia are borne in clusters at the extremities of the assimilatory filaments (Fig. 1b, e, f). At the tips of these filaments from one to six spermatangial mother cells are formed, each of which produces one to three spermatangia. The carpogonial branches are produced laterally on the assimilatory filaments (Figs. Ie, d, g, 2 d) and usually in the younger parts of the thallus-at times even before the assimilatory filaments are fully developed (Fig. 1d, g). They are generally formed on the cells behind the third or fourth furcation and are characteristically composed of three cells (Figs. 1d, 2a, b, d, h) but are sometimes four-celled. The mature carpogonium has a long trichogyne which projects beyond the peri-phery of the thallus. In a few instances sper-matia were seen attached to the tip of the trichogyne (Fig. 2d). After fertilization the content of the tricho-gyne is separated from that of the carpo-gonium proper (Fig. 2a, b, h). The carpo-gonium then divides by a transverse septum, forming a stalk cell and a gonimoblast initial (Figs. 2e, 3e) from which is produced the gonimoblast (Fig. 2e). The gonimoblast con-424 PACIFIC SCIENCE, Vol. X, October, 1956 FIG. 1. Liagora maxima Butters. a, Assimilatory filament, X553; b, e,j, antheridia, X2266; c, d, g, carpogonial branches, X 1133. Observations on Liagora-DESlKACHARY 425 . FIG. 2. Liagora maxima Butters. a-c, e-h, POSt fertilization stages; d, carpogonial branch showing trichogyne wIth attached spermatium. All X 1020. 426 sists of branched filaments (Figs. 2[, g, 3a-c) which form terminal carposporangia (Fig. 3c, d). Soon after fertilization of the carpogonium, involucral filaments are initiated. These fila-ments are formed by the vegetative cells above and below the supporting cell and rarely also by other vegetative cells in the neighborhood of the carpogonial branch (Fig. 2a, b, h) . The involucral filaments grow up and around the developing gonimoblast and are very much branched (Fig. 3a) . They are generally nar-rower than the gonimoblast filaments and have a dense cytoplasmic content. Later, ·as the development of the gonimoblast ad-vances, vacuolization of the cells of the in-volucral filaments becomes evident and the filaments ultimately lose most of their con-tents and become colorless (Fig. 3c). Concurrently with the formation of the gonimoblast, changes occur in the cells of the carpogonial branch. These cells acquire a dense content and increase in size, often becoming two or three times larger than they originally were (Fig. 2c, g) . The protoplasmic connections between the cells gradually widen, resulting finally in the establishment of a large fusion-cell, comprised of the sup-porting cell, the cells of the carpogonial branch, and the stalk cell (Figs. 2g, 3b,j) . The gonimoblast initial is not incorporated in the fusion-cell. At first , the fusion-cell has a dense content but later, as the gonimoblast continues growth, the content gradually be-comes vacuolated and less dense. The account of the development of the gonimoblast of Liagora maxima presented here is, in some respects, at variance with the description as given by Abbott (1945). Ac-cording to her the carpogonial branch is four-celled when mature. In the present investiga-tion, the mature carpogonial branches were almost always observed to be three-celled-only rarely do they become four-celled. This is the only species of Liagora, in addition to L. viscida (Kylin, 1930), in which a fusion-cell has been observed. According to Abbott the - ..... r1 ~ .• f' '--'r PACIFIC SCIENCE, Vol. X, October, 1956 involucral filaments are formed from the sup-porting cell, but in the present study they were observed to be produced by the vegetative cells above and below the supporting cell-never from the supporting cell. LIAGORA P APENFUSSII This species was described by Abbott (1945) from material collected by Papenfuss on the Island of Oahu. The writer's observa-tions are based on part of the same material. Liagora Papenfussii is the fourth of the known species of Liagora in which the gonimoblast has been observed to produce tetrasporangia instead of carposporangia (i.e., monosporan-gia) . The other three species are L. tetra-sporifera B¢rgesen (1927), Japanese specimens of L. pinnata Harvey (Yamada, 1938), and L. brachyclada Decaisne (Levring, 1941). B¢r-gesen (1927) and Kylin (1930) have made detailed studies of L. tetras porifera. In its de-velopment this species differs in some respects from L. viscida as observed by Kylin (1930). A short account of the main features of L. Papenfussii follows. The author's observations on this species agree entirely with those of Abbott and point to the distinctness of the speCles. STRUCTURE OF THALLUS: The thallus is composed of a core of large axial filaments from which issue radially directed assimila-tory filaments . These lateral filaments are divided four to six times, the distance be-tween the branches being quite short (Fig. 4a, b). The cells are short and barrel-shaped toward the axial part of the thallus and de-crease in length toward the periphery. They have a thick wall and are joined by con-spicuous cytoplasmic connections . In the younger parts of the thallus the assimilatory filaments often terminate in short hairs. REPRODUCTION: Liagora Papenfussii is mo-noecious. The spermatangia are produced in clusters at the tips of the assimilatory fila-ments. From the terminal cell of an assimila-tory filament two to three spermatangial mother cells are generally cut off, each of Observations on Liagora--DESlKACHARY 427 ~ \ \"" \J FIG. 3. Liagora maxima Butters. a-c, e, f, Post fertilization stages; d, carpospores. a, X605; b-f, X935. 428 which gives rise to two or three spermatangia (Fig. 4a, h). The carpogonial branches are produced as lateral accessory branches on the assimilatory filaments and usually behind the third or fourth furcation of these filaments. The car-pogonial branch initial is cut off as a lens-PACIFIC SCIENCE, Vol. X, October, 1956 shaped cell (Fig. 4e). By repeated division it gives rise to a four-celled branch, the terminal cell of which is the carpogonium (Fig. 4c, d, f, g) . In the mature condition the carpogon-ium has a long trichogyne which extends to the surface of the thallus (Fig: 5a) . After fertilization the cytoplasm of the d FIG. 4. L iagora Papenfussii Abbott. a, b, Old and young assimilatory branches, respectively; c- g, development of carpogonial branches; h, antheridia. a, X270; b, X 660; c- h, X 1020. . .. -- ~ Observations on Liagora-DESIKACHARY 429 FIG. 5. Liagora Papenfussii Abbott. a-I, POSt fertilization stages; g, old cystocarp showing tetrasporangia. a-d, /, X765; e, X495; g, X373. " 430 trichogyne is separated from that of the car-pogonium proper and the carpogoniumthen divides by a transverse wall (Fig. 5d) into a stalk cell and the gonimoblast initial. The gonimoblast initial gives ris~ to a much-branched gonimoblast (Fig . 5b, c, e, /). The gonimoblast filaments form terminal tetra-sporangia (Fig. 5g) . A fusion-cell is apparently not formed in this species. At times, however, a distinct enlargement of the cytoplasmic connections occurs (Fig. 5d,f). Only a slight development of involucral filaments occurs (Fig. 5b, e): A few filaments are formed from the vegetative cells above the supporting cell and occasionally from cells of the other vegetative filaments near the supporting cell. DISCUSSION AND SUMMARY The observations on Liagora maxima and L. Papenfussii have contributed to an elucida-tion of two points, in particular, in the de-velopment· of the cystocarp in Liagora. Previously the occurrence of a fusion-cell in the cystocarp of Liagora has been reported only in L. viscida (Kylin, 1930). The observa-tion of such a cell in L. maxima shows that this is a condition which may occur also in some of the other species of Liagora. An investigation of the numerous species of this genus with respect to this feature would be of interest. Involucral filaments have been reported as present in the cystocarp of a number 'of spe-cies of Liagora. In most instances authors have neglected to state from which cells these filaments are derived. It is also not possible to obtain this information from the published illustrations. According to K ylin (1930: 9), involucral filaments are not produced in L. viscida. Hamel (1930: 76), however, states that such filaments are present in this species and that they are formed by the cells of the carpogonial branch . Abbott (1945: 148) de-scribed the involucral filaments as issuing .. PACIFIC SCIENCE, Vol. X, October, 1956 from the supporting cell in L. maxima. The present writer's observations show that in the latter species they are produced by the vege-tative cells- above and below the supporting cell and rarely also by other vegetative cells in the vicinity of the carpogonial branch. Precise information on the place of origin of these filaments in the various. species of Lia-gora in which they occur is highly desirable. REFERENCES ABBOTT, ISABELLA A. 1945. The genus Lia-gora (Rhodophyceae) in Hawaii. Bernice P. Bishop Mus., Occas. Papers 18: 145=--169, 16 figs. BORGESEN, F. 1915- 1920. The marine algae of the Danish West Indies . Part 3. Rhodo-phyceae. Dansk Bot. Arkiv. 3: 1- 498 + index of 6 pp. , 435 figs . --- 1927. Marine algae from the Canary Islands ... III . Rhodophyceae Part 1, Bangiales and Nemalionales. K. Danske Vidensk. Selsk., BioI. Meddel. 6(6): 97 pp., 49 figs. BUTTERS, F. K. 1911. Notes on the species of Liagora and Galaxaura of the central Pacific. Minn . Bot. Studies 4 : 161-184, pI. 24. HAMEL, G . 1930. Floridees de France VI. Rev. Algologique 5: 61- 109, figs. 41- 59. KYLIN, H. 1930. tiber die Entwicklungsge-schichte der Florideen. L unds Univ. Arsskr. N. F. Avd. 2, 26(6): 1- 104, 56 figs . LEVRING, T . 1941. Die Meeresalgen der Juan Fernandez-Inseln. In, C. Skottsberg, The natural history of J uan Fernandez and Easter Island. Vol. 2, 211 pp., Almgrist & Wiksells, Uppsala. PAPENFUSS, G . F. 1946. Structure and repro-duction of Trichogloea Requienii, with a com-parison of the genera of Helminthocladia-ceae. Torrey B ot. Club, Bul. 73: 419-437, 26 figs. YAMADA, Y. 1938. The species of Liagora from Japan. Hokkaido Imp. Univ ., Fac. Sci., Inst. Algol. Res., Sci. Papers 2(1): 1-34, 22 figs ., 15 pIs . 

Observations on Two Species of Liagora (Rhodophyta)

http://scholarspace.manoa.hawaii.edu/bitstream/10125/8712/1/v10n4-423-430.pdf

Observations on Two Species of Liagora (Rhodophyta)

Abstract

Similar works

Full text

Available Versions

ScholarSpace at University of Hawai'i at Manoa