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Pterocanium elegans (Haeckel, 1887)

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Benson, 1966, p. 403-405; pl. 27, figs. 1-2:

Pterocanium cf. elegans (Haeckel)

?Artopilium elegans Haeckel, 1887, Challenger Rept., Zool., vol. 18, p. 1440, Pl. 75, fig. 1.

Test consisting of three joints, a cephalis, thorax and abdomen; with heavy, long, three-bladed apical and vertical horns and three feet originating from near or above the base of the thorax. Cephalis subspherical with small, subequal, subcircular to elliptical pores; separated from thorax by a change of contour, not a distinct stricture. Apical horn ascends dorsally in the sagittal plane from the apical bar which is a dorsal rib in the wall of the cephalis; horn long, heavy, three-bladed, latticed proximally. Vertical horn ascends ventrally in the sagittal plane, extends from the thin, cylindrical vertical bar which is free within the cephalic cavity; horn similar to apical horn, latticed proximally. Four collar pores present at base of cephalis; ventral arch and apical-lateral arches present as ribs in the wall of the cephalis. Thorax long, pyramidal with three flat sides each extending between the dorsal and primary lateral thoracic ribs. Pores of thorax small, equal, hexagonal to subcircular, arranged hexagonally in transverse rows, separated by thin intervening bars. In one test three continuous transverse ribs present but do not correspond to constrictions of the thorax (Pl. 27, fig. 2). Dorsal and primary lateral bars of the collar region thin, cylindrical, extend as ribs in the wall of the thorax for most of its length and terminate in heavy, three-bladed, proximally latticed feet which are straight or curve slightly upward and originate at or slightly above the region of maximum breadth of the thorax. Thin, cylindrical accessory spines (18-31 µm) originate from the thoracic ribs, lie in the plane of the ridge-like ribs, and are joined by a small pored lattice to the ribs; in fully developed tests these spines and attached lattice when joined together resemble a keel originating from the thoracic rib. Abdomen circular to triangular in section, with pores similar to those of the thorax, not joined to the feet of the test, straight sided thus nearly cylindrical, not constricted distally, with numerous (6-12 or more) straight, thin, conical terminal spines (25-74 µm) originating from its distal margin. Abdomen separated from thorax by a distinct inward change of contour and in a few tests also by an internal septal ring.

Measurements; based on 4 specimens from stations 60, 81, and 115: length of cephalis 23-26 µm, of thorax 111-160 µm, of abdomen 49-86 µm; breadth of cephalis 23-27 µm, of thorax (maximum) 149-205 µm, of abdomen (maximum) 144-205 µm; length of apical horn 18-92 µm, of vertical horn 22-92 µm, of feet 31-139 µm.

Remarks. This species is nearly identical with Haeckel’s illustration of Artopilium elegans (Haeckel (1887, Pl. 75, fig. 1) which has four joints, the joint corresponding to the thorax in the Gulf specimens subdivided into a small proximal joint (thorax) and a larger joint (abdomen) similar to the thorax of the Gulf species; therefore, the feet originate from the base of the abdomen in Haeckel's species. Whether or not the presence of the small proximal joint is subject to intraspecific variation could not be determined from study of the Gulf material because of the very rare occurrence of this species in the Gulf. In all other aspects the Gulf species is identical. to Artopilium elegans Haeckel

Distribution. This species is very rare in the Gulf. It is present at stations 34, 64, 81, 91, 93, 95, 115, 133, and 151. Except station 64, these stations are located in the axial region of the Gulf; therefore, this species has affinity for offshore, more nearly oceanic waters.
Haeckel (1887, p. 1440) reported Artopilium elegans from the central Pacific at "Challenger" station 274. Species similar to this species or the Gulf species have not been reported elsewhere.
Benson 1966











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