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Dictyophimus splendens (Campbell and Clark, 1944)

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Pterocorys (Pterocyrtidium) splendens
Shell large, generally conical (45°), with a greatly elongated, sinuous, vertical, rodlike apical horn (its length about three times that of a radial apophysis), tip sharp, horn forming one of remarkable, striking characters of species; cephalis relatively small, conical (50°), its apex blunted, its sides plane, and basal diameter 0.32 length of a radial apophysis; thorax subcorneal (40°), its length approximately 0.9 radial apophysis, its basal diameter nearly 0.75 radial apophysis, and its sides rather strongly bulged, especially toward middle, at its upper end cervical suture weak, but at thoracic base a strong, raised, circular, transverse rib cuts off thorax from abdomen below it (lumbar suture) and extends beyond latter; abdomen subcylindrical (hollow-sided), greatly damaged in all of our specimens but apparently at least as long as 0.5 radial apophysis, and with diameter somewhat less, free margin not clear; projecting from thorax, freely extending from transverse rib are three, long, thick, very strong, equi­ distant, clawlike radial apophyses, these curved inwardly, distally sharp, triangular in section, triangles bladelike, apophysis continued upon thorax surface trending along contour toward neck as decurrent, linelikc, raised ribs; shell-wall thicker in thorax than elsewhere and in abdomen a mere basketwork; surface in optical section rough in thorax, elsewhere smooth; cephalis poreless and glass-clear, thorax with about 40 large, more or less equal, subcircular, fairly shallow, well-separated, nar­rowly double contoured pores with wide framework, pores of abdomen, with numerous, subcircular to squarish, unequal pores and a delicate framework. Length, total (ap­proximate), 470 ė, of apical horn, 370 ė, of shell, 150ė, of radial apophysis, 120 ė; diameter, transverse rib of thorax, 90 ė, of thoracic pores, 12 ė, of largest abdominal pores, 24 ė.
Pterocorys splendens n.sp. differs from all other described species in great elonga­tion of horn. One of most unusual of radiolarians and a distinct "find" in this Terti­ary material. Nearly all specimens are rather badly injured, and our complete (nearly) figured individuals are remarkable in preservation and rare beauty.
Campbell and Clark 1944
Dictyophimus splendens
Cephalis hemisphaerical, poreless, hyaline. Inside the cephalis both the apical and vertical spines are free of the shell wall. Externally the apical spine is prolonged into an unusually long cylindrical horn tapering to a point distally. In our North Pacific material, the horn is up to four times as long as the cephalothorax, but in tropical material it may even be longer. Campbell & Clark's (1944) original description described the horn as "sinuous" but it may also be straight or curved. Collar stricture indistinct. thorax conical, thick-walled, sometimes thorny, with subcircular pores increasing in size distally, 4 to 6 on a half equator at the base of the thorax. Indistinct thoracic ribs become external just above the termination of the thorax and are prolonged into three weakly bladed or cylindrical wings tapering to a point distally. Wings diverge freely, forming an extension of the conical line of the thorax. Thoracic termination smooth or may have irregularly placed, inwardly curving teeth or projections or other indications of the beginnings of an abdomen. Abdomen irregular, varying in state of development and having pores similar to those on the thorax. Termination ragged.
Dimesions (basd on 20 specimens). Length of cephalis= 15-22 ėm, length of thorax= 55-100ėm, length of abdomen= up to 45ėm, maximum breadth of cephalis= 18-30ėm, maximum breadth of thorax= 65-100ėm, length of wings= up to 65ėm, length of apical horn= up to 275ėm. Campbell & Clark (1944) report a length of 370ėm for the apical horn.
Distinguishing characters. The extraordinary length of the apical horn of this species distinguishes it from all others.
Remarks. It is likely that the form described by Riedel (1952, p.7, pl.1, fig.2) as Pterocorys splendens Campbell & Clark albatrossensis Riedel from the western tropical Pacific is a synonym of Dictyophimus splendens, but it would be necessary to examine topotypic material to verify this synonymy.
Morley and Nigrini 1995


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