| Home> Gulf of California>

List species

Phormospyris sp. det. Benson, 2003

Description - Add description

Benson, 1966, p. 326-329; pl. 22, fig. 22; pl. 23, figs. 1-2:

Patagospyris? sp.

Smooth bilocular cephalis with small circular pores separated by wide intervening bars; two pairs of sagittal pores on the dorsal, upper, and ventral faces of the cephalis, the dorsal pairs larger than those of the other two faces. A thin, conical apical spine extends from the straight apical bar of the sagittal ring; it has 2-3 small branches arising from it near its base, and in several specimens a low, small, smooth, small-pored, flat-topped cupola is developed from these spines and covers the medially constricted portion of the upper cephalic face (Pl. 23 fig. 2). A short, thorn-like, barely visible vertical spine is present. Sagittal ring asymmetrical, three-bladed with one blade extending inward in the sagittal plane and two blades extending laterally outward. Four large collar pores, the cardinals and cervicals, present. The species characterized by a latticed thorax partially developed between 2-9 (generally 3-4) conical, foot-like spines arising from the collar ring. These spines correspond to the dorsal and primary and secondary lateral spines of the collar ring and the cardinal spines arising from the lateral margins of the cardinal pores, all of variable state of development, and in all specimens a pair of well-developed, downward-divergent spines or feet, each spine originating from the ventro-lateral margin of each cervical pore. The partial thorax is first developed ventrally between the last pair of spines mentioned; a convex downward arch is developed between these spines, and distally from this arch an apron-like lattice is developed that consists of a few circular to elliptical pores separated by wide intervening bars; it terminates in a few thin, conical spines; between the arch and the ventral margin of the cervical pores is a large subcircular to elliptical gate characteristic of the species; the apron-like ventral thoracic lattice is represented in various states of development, but the distal branching and partial formation of the arch between the ventral spines or feet originating from the margin of the cervical pores serves to distinguish the species. The other spines originating from the collar ring curve gently downward from the ring; the primary and secondary lateral foot-like spines are forked distally, in several specimens one of the forked spines is horizontal; the cardinal spines when present are short, thin, conical; the dorsal spine in several specimens has a lattice partially developed laterally from it. The ventral, apron-like thoracic lattice joins dorsally with the inner distal branches of the primary lateral spines in more fully developed specimens. No specimens were observed with thoracic lattice completely developed around the circumference.

Measurements; based on 30 specimens from station 92: sagittal height of cephalis 41-59 µm, maximum breadth 78-123 µm; length of thoracic "apron" 31-56 µm, maximum breadth 57-89 µm; length of apical spine 5-22 µm.

Remarks. The presence of numerous basal foot-like spines (9-12 or more), of a thorax, and of a single apical spine are the definitive characters of the genus Patagospyris Haeckel (1882, p. 443). Although the thorax is only partially developed and the cephalis bears a small apical cupola in fully-developed forms of the Gulf species, it was placed tentatively in Patagospyris. The only species that resembles the Gulf species is Acrospyris clathrocanium Haeckel (1887, p. 1087, Pl. 95, fig. 17). This species has a heavy, conical apical horn with three secondary spines originating from near its base but no apical cupola. It has three, large, splayed feet with a partially developed lattice between each of them and a large gate between this lattice and the cephalis, thus three gates in all. The Gulf species has only the ventral, apron-like, thoracic lattice and one gate, and the feet are smaller and more numerous; therefore, it is not identified with A. clathrocanium Haeckel. The thorax of the Gulf specimens appears to be incompletely developed, and study of a greater number of specimens may reveal its affinity with a previously described species. For this reason a new name for this taxon is not proposed.

Distribution. This species is rare but cosmopolitan in the Gulf, occurring as far north as station 192. It is absent at stations 64, 90, 130, 194, and all those to the north. Its absence at these marginal stations indicates its preference for offshore waters. Its frequency throughout the Gulf is very low and undergoes no significant fluctuations. It apparently does not respond to upwelling, although its general occurrence in the northern Gulf may be due to its response to upwelling there; however, this cannot be determined from the numerical data alone. This species, therefore, is able to inhabit both oceanic and Gulf waters but does not thrive in nearshore or shelf environments.
Benson 1966











Discussion / Comments


Web links