42 



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



Ceratocorys reticulata n.sp. 

 (Figure 55) 



Dimensions. This is the largest species of the ge- 

 nus. Length of body Q) 93 (84-98) microns. Diameter 

 of body (d) 99 (86-114) microns. Greatest diameter of 

 body Is at the girdle. Four specimens were measured. 



Shape . In ventral aspect the body is almost dia- 

 mond-shaped, somewhat truncated posteriorly (fig. 55A). 

 This species is unique in that the body width always ex- 

 ceeds the length; Vd ratio is 0.94 (0.86-0.97). Epitheca 

 subcorneal, the highest of any species of the genus. The 

 e/i ratio Is 0.42 (0.40-0.46). Thus, the girdle is nearly 

 equatorial. At girdle, body is nearly circular with a de- 

 pression ventrally (fig. 55B). The wide girdle region 

 and almost pointed antapex result in a comparatively ob- 

 tuse angle j9, the greatest of the genus: 37° (38°-39°). 

 The two sides of hypotheca nearly equal in length. An- 

 terior displacement of ventral side of antapex very small 

 (fig. 550). Girdle displaced about 1 girdle width. 



Thecal wall . Surface completely covered with a 

 heavy reticulation except in parts of ventral area and on 

 the posterior intercalary plate. Pores could not be dem- 

 onstrated in the meshes of this network nor in the girdle. 



Plate pattern . Left sulcal plate extends sufficient- 

 ly far forward so that the right sulcal plate does not 

 touch flagellar pore. 



Lists . Girdle lists short, approximately 1 girdle 

 width wide, strengthened with regularly spaced ribs run- 

 ning from the body completely to outer edge. These ribs 

 are continuous with the girdle transverse lists and di- 

 vide girdle into a series of chambers. Body lists typi- 

 cal of genus. All sutures clearly indicated by low lists 

 or thick ridges. Right sulcal list usually supported by 

 several heavy spines (fig. 55C). 



Spines . Dorsal and ventral spines absent. Antapi- 

 cal spines simple, three in number; one of them ventral 

 at posterior end of sulcus, the other two dorsal. The 

 latter are connected with the antapical lists by their own 

 connecting lists (fig. 55D). 



Reproduction . Division stages were not found. In 

 the specimen shown in figure 55, however, the lists of 

 the right half of the body were not all well developed, in- 

 dicating a certain degree of immaturity of the specimen. 



Variation . The species is constant. Variations in 

 size and shape have already been given above. 



Distribution . In the Carnegie collection this species 

 was found at 30 stations: 1 in the Atlantic, 29 in the Pa- 

 cific. There are 41 records of occurrence: 36 rare and 

 5 occasional. The species was found somewhat more 

 often at 50 meters than at other depths, with 9 records 

 for the surface, 20 for 50 meters, and 12 for 100 me- 

 ters. There are 4 pump records and 37 net records. 

 The species was found In both hemispheres and from 

 September to May. 



Ceratocorys reticulata Is a distinctly tropical spe- 

 cies. Although it occurred at scattered stations as wide- 

 ly separated as Guam and Panama, it was not found 

 north of latitude 30° north in the North Pacific nor south 

 of 18° south in the South Pacific (fig. 52). In the Atlantic it 

 occurred at 13° north, in the North Equatorial Current. 



The surface temperatures at the station where the spe- 

 cies occurred^t any depth variedfrom20!4 to 29°5 C. The 

 ranges of hydrographic conditions in situ were as follows: 

 temperature, 19°5 to 29°.3C; salinity, 30.0 to 36.3 o/oo; 

 pH, 8.09 to 8.42; phosphate, 3 to 60 mg P04/m3. Type 

 locality: Carnegie station 28. 



Ceratocorys aultii n.sp. 

 (Figure 56) 



Dimensions . Length of body Q) 68 (63-71) microns. 

 Diameter (d) 61 (55-65) microns. Three specimens 

 were measured. 



Shape . Similar in general appearance to C. skogs - 

 bergii, which belongs to the subgenus Protoceratocorys . 

 Slightly longer than wide. The^/d ratio is 1.11 (1.09- 

 1.15). Epitheca high dome-shaped to subcorneal. The 

 e/l_ ratio is 0.35 (0.30-0.38). Girdle displaced about 2.5 

 girdle widths. Body almost circular in apical view. 

 Antapex broad; angle j3 thus comparatively acute: 21° 

 (20°-21°). Posteroventral obliquity pronounced (fig. 

 56D). In specimens with wide intercalary zones, the 

 dorsal antapical spines are displaced ventrally so that 

 there is a flattening of the antapex dorsal to the spines 

 which produces a superficial resemblance to C. skogs - 

 bergii (fig. 56D). 



Body wall . Surface regularly covered with small 

 pits. Intercalary zones covered with a faint network of 

 large reticulations. Ventral epithecal pore inconspicu- 

 ous. Pores scattered in sulcus (fig. 56A). 



Plate pattern . Left sulcal plate extends anteriorly 

 so that the right plate is quite remote from flagellar 

 pore (fig. 56A). 



Lists. Girdle lists of medium width; about 1.5 to 

 2.0 girdle widths wide. Strengthening ribs usually not 

 well developed. Transverse girdle lists, however, well 

 developed, as are sulcal lists. General body lists not 

 well developed. 



Spines . Dorsal and ventral spines absent. Four 

 antapical spines at the four corners of antapical plate. 

 Spines simple, about 3 to 4 girdle widths long. The dor- 

 sal and left members connected by a common list (fig. 

 56A, B, D), as are sometimes the ventral and right 

 spines. Left sulcal list runs onto ventral antapical 

 spine. Ventral and left sometimes closely approximat- 

 ed. It is not unlikely that in some specimens these 

 spines may be fused into one spine, considering that this 

 condition is sometimes found in C. armata, of which 

 much more material is available. 



Reproduction . Daughter cells were not found. 



Distribution . In the Carnegie collection this species 

 was found at 15 stations, all in the Pacific. There are 

 21 records of occurrence, all rare. The species was 

 found more frequently with increasing depth, with 5 rec- 

 ords for the surface, 6 for 50 meters, and 10 for 100 

 meters. There are 14 net records and 7 pump records. 

 The species was found in both hemispheres; during Jan- 

 uary to May in the southern hemisphere, in September 

 and October in the northern hemisphere. 



The stations at which this species was found are in 

 widely -scattered regions of the North and South Pacific 

 (fig. 52). Three of these stations are east of Guam; 

 four between San Francisco and Hawaii; four near the 

 Samoan Islands; one east of the Tuamotus; and three 

 south and east of Easter Island. 



The surface temperatures at the stations where the 

 species occurred at any depth varied from 16°.9 to 

 29°.5 C. The hydrographic conditions in situ were as 

 follows: temperature, 14°.3 to 29°.3 C; salinity, 34.4 to 

 36.3 o/oo; pH, 8.05 to 8.39; phosphate, 3 to 46 mg 

 P04/m3. 



Ceratocorys aultii is a rare, tropical species, prob- 

 ably widespread in tropical waters but seldom collected 

 because of its sparse population. Its greatest abun- 



