40 



STUDIES IN THE MORPHOLOGY, TAXONOMY, AND ECOLOGY OF THE PEMDINIALES 



Distribution . Ceratocorys horrida is a widespread 

 tropical and subtropical species. It has been found fre- 

 quently in the Atlantic (Schutt, 1895; Jorgensen, 1911b; 

 Dangeard, 1927c; Pavillard, 1931). It is common in the 

 Mediterranean (Gourret, 1883; Daday, 1888; Kofoid, 

 1910; Pavillard, 1916; Lindemann, 1925; Issel, 1928). In 

 the Pacific it was reported from the open North Pacific 

 by Lemmermann (1899), from San Diego by Kofoid (1910), 

 and from Japan by Schroder (1906) and Okamura (1907). 

 It also occurs in the Indian Ocean (Karsten, 1907; Mat- 

 zenauer, 1933). 



In the Carnegie collection the species was found at 

 114 stations: 18 in the Atlantic, 96 in the Pacific (fig. 

 52). There were 360 records of occurrence; 154 rare, 

 162 occasional, and 44 common. It was found less fre- 

 quently with increase in depth, with 159 records for the 

 surface, 113 for 50 meters, and 88 for 100 meters. 

 There were 273 net records and 87 pump records. It 

 was found in both hemispheres and in practically all 

 months of the year. 



This species occurred at almost all the Carnegie 

 stations in the tropics (fig. 52). In the Atlantic it oc- 

 curred at all but six stations south of 40' north; in the 

 North Pacific it occurred at all but one station south of 

 35° north; in the South pacific it occurred at all stations 

 north of 34° south except in the regions near South 

 America. It was absent in the Humboldt Current at 

 three stations near the Galapagos. It was rather uni- 

 formly distributed throughout its range; the records of 

 "occasional" and "common" were widely scattered 

 throughout the tropics. 



The surface temperatures at the stations where it 

 occurred at any depth varied from 17 °5 to 29°. 5 C. The 

 ranges of hydrographic conditions in situ were as fol- 

 lows: temperature, 11°4 to 29°5 C; salinity, 29.7 to 37.0 

 o/oo; pH, 7.17 to 8.47; phosphate, 2to 189 mgP04/m3. 

 Although C. horrida is never abundant, it is one of 

 the commonest of the tropical peridinians. For this rea- 

 son it is an excellent indicator of tropical water. Ac- 

 cording to the Carnegie observations the species does 

 not endure any great lowering of the temperature and 

 consequently would not indicate water of tropical origin 

 very far from its source. For instance, in the North 

 Atlantic Drift the species drops out suddenly where the 

 water temperature at the surface falls below 19° C (sta- 

 tion 3). In the cold California Current it was not found 

 until the temperature had risen to 19°3 C (station 131). 

 South of Easter Island in the southeastern Pacific it a- 

 gain dropped out where the temperature fell below 19° C 

 (station 58). Off Japan it was not found in water with a 

 surface temperature below 23° 2 C. 



These observations indicate that the active repro- 

 duction of C. horrida probably does not take place in 

 water of a temperature below 20° C and that the organ- 

 isms carried Into cooler regions seldom survive a tem- 

 perature below 19° C. In the region off South America 

 this species was conspicuously absent at 13 stations 

 where the temperature at the surface was above 19°. At 

 these stations the temperatures were mostly between 

 19° and 21° although at stations 71 to 74 the tempera- 

 tures were from 23°.5 to 25°3 C. The absence of C. hor- 

 rida from this series of stations can probably be attrib- 

 uted to the influence of the Humboldt Current, which is 

 composed of water of antarctic origin mixed with water 

 upwelling along the coast. The movement of this water 

 has a westerly component away from the continent. This 

 water is being constantly warmed as it progresses. 



Even though it may reach a temperature sufficiently high 

 for Ceratocorys horrida , however, it does not contain 

 this species because of the lack of inoculation. Thus, 

 the eastern limit of the species in this region is pushed 

 westward by the drift from the edge of the Humboldt Cur- 

 rent. Inoculation probably takes place along this border 

 in an irregular and sporadic nature during fluctuations 

 of the dynamic conditions, probably through eddies from 

 the Easter Island region. That this type of inoculation is 

 probable is suggested by the isolated occurrence of C. 

 horrida at station 61a, with a surface temperature of 

 17°5, the only record where the temperature was below 

 19°. The water in that region must have been a local 

 mass very recently detached from the tropical mass to 

 the northwest. 



Ceratocorys horrida is probably an important or- 

 ganism in the economy of the tropical and subtropical 

 seas. It was found throughout the regions where the 

 phosphate content of the water was less than 10 mg 

 P04/m3. At many of these stations the observed values 

 were less than 5. The nitrates, it is assumed, were e- 

 qually low. The nutrient requirements of this species 

 must be extremely low. 



The wide range of salinities in which the species 

 was found indicates that the species is not very sensi- 

 tive in respect to the salinities found in oceanic condi- 

 tions. It occurred in the Panamic region in salinities as 

 low as 29.7 o/oo. 



Ceratocorys armata (Schutt) Kofoid 

 (Figvires 53, 54) 



Ceratocorys armatum Kofoid, 1910, p. 181. 

 Ceratocorys armata , Schiller, 1929, pp. 412-413, fig. 



31a, b. Forti, 1922, p. 83, pi. 6, fig. 72. 

 Goniodoma acuminatum var. armatum Schutt, 1895, p. 



153, pi. 9. figs. 32(1), 32(2). Lindemann, 1925, p. 



98, figs. 5,6. 

 Goniodoma fimbriatum Murray and Whitting, 1899, p. 



52S71)1. 27, fig. la, b. 



Ceratocorys spinifera Murray and Whitting, 1899, p. 329, 



pi. 30, fig. 6c. 

 Goniodoma armatum , Schmidt, 1901, p. 135. 

 Gonyaulax ~ fimbria.tum Schr5der, 1906, p. 329. 

 y Cerato"c"orys armata , Matzenauer, 1933, p. 453, fig. 22. 



Dimensions . Length of body (J.) 79 (54-99) microns. 

 Diameter (d) 70 (47-93) microns. Greatest diameter of 

 body at the girdle. Thirty-five specimens were meas- 

 ured. 



Shape . In ventral aspect body roughly ovate to kite- 

 shaped (fig. 53A). Thei/d ratio is 1.09 (0.97-1.24). 

 Epitheca triangular to high dome-shaped. The e/l_ ratio 

 is 0.38 (0.31-0.46). At girdle the body is squarish to 

 circular with a ventral depression. Girdle displaced 

 about 1.5 girdle widths. Antapex narrow, so that the 

 angle j3 is comparatively obtuse: 31° (22°-38°). Hypo- 

 theca cut off obliquely so that the ventral end of antapi- 

 cal plate is about one-third of the way to girdle from the 

 dorsal end. Thus, the body is much more angular in lat- 

 eral view than in the ventral aspect (fig. 53D). 



Plate pattern . Right sulcal plate is much longer 

 than in other species and extends posteriorly for half its 

 length into a shoulder of the posterior sulcal plate (fig. 

 53). Left sulcal plate short, so that the right sulcal plate 

 touches the flagellar pore. 



Body wall . Thecal wall regularly pitted on all major 

 plates except along the suture zones. In these zones 



