66 



THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES 



S. BRYOPSIDIS (dt- Bruyne) Petersen, I.e., p. 479. Fig. 

 XI, 1-8. 

 Olipidium Bryopsidis de Bruyne, 1890. Areh. Biol. 10: 

 85. PI. 5, fig's. 1-15. 



Thallus usually intramatrical, becoming partially 

 extramatrical under certain conditions ; small, uni- 

 cellular and olpidioid, or elongate, tubular and fila- 

 mentous ; frequently becoming septate and undergo- 

 ing fragmentation into unicellular segments which 

 develop into sporangia. Zoosporangia usually nu- 

 merous in a cell, hyaline and smooth, spherical, oval, 

 ellipsoid, 12-17 xx'x 13-38 xi, elongate, cylindrical, 

 tubular, 3-5 xi X 6-165 /x. Zoospores narrowly pyri- 

 form and slightly arched, 2 X 4 /x, with a refring- 

 gent granule at the anterior end; flagella inserted 

 near the anterior end ( ?). Resting spore (?) spheri- 

 cal, oval and elongate, hyaline and smooth, germi- 

 nation unknown. 



Parasitic in Bryopsis plumosa in Italy (de 

 Bruyne, I.e.), Denmark (Petersen, I.e.; Sparrow, 

 '34) and Massachusetts, U. S. A. (Sparrow, '36); 

 and saprophytic (?) in Cladophora sp., in Massa- 

 chusetts, U. S. A. (Sparrow, I.e.). 



In material studied at Woods Hole, Mass., Spar- 

 row found that the growth of the thallus may be 

 markedly influenced by environmental conditions. 

 When the host is removed from its normal habitat 

 and exposed only to dripping sea water the fungus 

 grows out of the host and becomes distinctly filamen- 

 tous and hypha-like. Sparrow found that additional 

 extramatrical growth could be induced by transfer- 

 ring the infected material to solutions of low sugar 

 concentrations. It is obvious from these preliminary 

 culture studies that .S'. Bryopsidis is highly variable 

 in growth and development. 



S. LAGENIDIOIDES comb. nov. 



Pontisma lagenidioides Petersen, I.e., figs. X, 1-3. 



Thallus intramatrical, occasionally unicellular, 

 lobed, curved and olpidioid; usually elongate, lobed, 

 irregular and septate, frequently constricted at 

 septa; rarely fragmenting into isolated segments. 

 Zoosporangia hyaline and smooth, usually con- 

 nected, occasionally free; oval, elliptical, 13-15 xi 

 X 14-16 /x, elongate, cylindrical, 130-200 /x in 

 length, or irregular and slightly lobed. Zoospores 

 pvriform and arched, 2.5-3 xi X 4.5-7 p., with a re- 

 fractive granule at one or both ends ; flagella later- 

 ally inserted (?) on the concave side and oppositely 

 din cted; occasionally liberated within the host cell; 

 motion erratic and tumbling in swimming. Resting 

 spores unknown. 



Weakly parasitic or saprophytic in Ceramium 

 ntbritm, Ceramium sp., C. fructiculosum, C. tenuis- 

 simiim, and C. diaphanum in Denmark (Petersen. 

 I.e.; Sparrow, '34) and Massachusetts, U. S. A. 

 ( Sparrow, '36). 



Sparrow reported that the zoospores of this spe- 

 cies are strikingly similar to those of Butler's (I.e.) 

 Rozellopsis inflaia, and believed that on these 

 grounds Butler's species shows affinities with S. 



lagenidioides and species of Olpidiopsis. It is to be 

 noted again, however, that the flagella of S. lageni- 

 dioides (fig. 3, plate 17) also appear to be attached 

 to the narrow anterior end of the zoospores. 



PETERSENIA 



Sparrow, 1934. Dan.sk. Bot. Ark. 8: 13. 



(PLATE 18) 



Thallus entirely intramatrical, unicellular, elon- 

 gate, narrowly cylindrical, irregularly lobed and 

 contorted, rarely ellipsoid, and olpidioid; occupying 

 one or more host cells. Zoosporangia solitary or nu- 

 merous, variously shaped with 1 to 4 exit tubes of 

 variable length. Zoospores laterally (?) biflagellate, 

 isocont; flagella extending in opposite directions; 

 developing completely and swarming in the sporan- 

 gium before emerging, swimming directly away 

 without anj T pause at the mouth of the exit tube. 

 Resting spores doubtful or unknown. 



This genus was established to include species of 

 Pleotrachelus which were found to have biflagellate 

 zoospores. It is not improbable that other marine 

 species of the latter genus may also be transferred to 

 Peiersenia when their life cycles and method of de- 

 velopment are completely known. Petersenia an- 

 dreei is apparently a species of Olpidiopsis and is 

 accordingly excluded from this genus which leaves 

 only one valid species, P. lobata. The thallus of 



PLATE 17 



Si ml i lid in in lagenidioides 

 (Fig. 1 after Petersen, '05; figs. 2-9 after Sparrow, '34.) 



Fig. 1. Elongate irregular septate, constricted thallus 

 with four exit tubes. 



Fig. 2. Arched zoospores with a refractive granule at 

 each end and two equal, laterally (?) attached flagella. 



Fig. 8. Free hand drawing and interpretation of zoo- 

 spores showing flagella attached near anterior end. 



Fig. 4. Irregular septate thallus. 



Fig. 5. Group of thalli showing "rudimentary fragmen- 

 tation." 



Fig. (i. Vacuolate sporangium with a branched exit tube. 



Fig. 7. Curved elongate, continuous and solitary spo- 

 rangium with quiescent zoospores. 



Fig. 8. Emergence of zoospores. 



Fig. 9. Empty loosely attached sporangia. 



ISIii.stiiliilinp.iis chattoni 



(All drawings after Sigot, '31) 



Fig. 10. Young vacuolate lobed thallus in egg of Cy- 

 clops. 



Fig. 11. Section of Cyclops egg showing lobes of spo- 

 rangium in section; nuclei lying in a thin peripheral layer 

 of cytoplasm. 



Fig. 12. laterally biflagellate isocont zoospore with nu- 

 cleus near the center and a large refringent body at the 

 anterior end. 



