radiolaria - rads_cat - Lophophaenoma witjazii

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Other pages this level: L. arctissa, L. petrushevskayae, L. witjazii

Lophophaenoma witjazii

Citation: Lophophaenoma witjazii Petrushevskaya 1971

Type repository: Holotype on preparation No. 269, Q50.0, Marine Dept., Zoological Institute, Acad. of Sc., St Petersburg, Russia

Family (traditional): Plagiacanthidae

Lophophaenoma with a downwardly narrowed I segment. The width of the II segment exceeds 1.2-1.3 times the width of the I segment. Downwards, the II segment is cylindrical. On the I segment the pores are rounded, whereas on the II segment they are irregularly shaped. The largest pores are in the area of the junction of the segments, whereas the smallest ones are located on the upper part of the 1 segment. Spine A, as well as the upwardly oriented apophyses p of the lateral spines, penetrate the lower walls of the I segment and then extend outside, forming laterally dispersing horns. Besides the mentioned horns, there are sometimes 1-2 similarly faceted secondary horns. There is no horn on the apex of the I segment. Spines D, Lr and Ll yield short lateral appendages. (In Russian. Translation via W.R. Riedel)

(Based on 11 specimens) Length of I segment 45-55µm; width approximately 40µm; length of II segment up to 50µm, width approximately 60µm.

This species was named in honor of the Soviet Research-Vessel "Vityaz”.

Distinguishing characters: The described species is extremely close to Lithomelissa decacantha Hck. (fig. 62, I), the skeleton of which we discovered in bottom sediments, the age of which according to Riedel (Friend and Riedel, 1967) corresponds to the Middle Miocene. At the present time, L. decacantha is either completely extinct or on the verge of extinction. We succeeded in finding only one specimen (fig. 62, II) which is sufficientlv similar to L. decacantha in the samples we examined. The difference between L. witjazii and L. decacantha lies in the distribution of pores and horns.
L. witjazii resembles in many respects the soecies described by Popofsky as Lithomelissa horrida Popofsky, 1917 (fig. 57, VIII), but differs from it in having a narrower thorax, as well as in the form of the outer extensions of spines D, Lr and Ll and in the smaller measurements.
L. horrida occurs in the plankton very rarely (discovered only at Station 3434); its skeletons are sometimes also encountered in the sediments of the tropical areas (station 4522, “Vityaz") Popofsky considered the species he described as representative of the genus Lithomelissa subgenus Sethomelissa. Campbell (1951) suggested to change the name of the subgenus Sethomelissa to Corythomelissa, since the name Sethomelissa Hck., 1831 was used by Haeckel (Haeckel, 1887) in a different sense, i.e. as a generic name for the genus, where Campbell isolated Sethomeliss hymenoptera Hok. 1887 as type species. According to Haeckel, S. hymenoptera is a species which is very close to Dictyoceras (Eucyrtidiidae). For Corythomelissa Campbell established Lithomelissa corythium Ehr., 1873 as type species, which, according to Ehrenberg’s illustration, belongs to Clathromitrinae and is definitely far from Lophophaenoma. Therefore we cannot relate the above mentioned species (L. horrida and L. witjazii) to Corythomelissa.

Circumtropical. Confined to warm surtace-waters.

References:

Petrushevskaya, M. G. (1971d). Radiolyarii Nasselaria v planktone Mirovogo okeana [Nasellarian radiolarians in the plankton of the world ocean]. Trudy Zoologicheskogo Instituta Academiya Nauk SSSR. 9(17): 1-294. gs O

CATALOG OF ORIGINAL DESCRIPTIONS: Lophophaenoma witjazii Petrushevskaya 1971

Lophophaenoma witjazii

References:

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