Genus Spiroplectammina


Spirioplectammina Cushman, 1927



Spiroplectammina biformis (Parker and Jones, 1865)

Textularia agglutinans d’Orbigny var. biformis Parker and Jones, 1865, p. 370, pl. 15, figs. 23, 24.

Spiroplectammina biformis (Parker and Jones, 1865) Loeblich and Tappan 1953, p. 34., pl. 4, figs. 1-6.;  Nørvang, 1966, p. 13-114;  Vázquez Riveiros and Patterson, 2008, figs. 5.6a-c.

Cushman (1927) erected the genus Spiroplectammina based on the species S. biformis. Nørvang (1966) emended this description to include features of the aperture


Type description: Test with the characteristics of the subfamily Spiroplectammininae. Test with the early chambers distinctly planospiral in both microspheric and megalospheric forms; later chambers biserial; wall arenaceous.


Emended Type Description.  Test free, polythalamous, chambers of the initial end planospirally arranged both in the megalospheric and microspheric generations, later chambers biserial; wall arenaceous, imperforate, aperture interior-marginal with no distinct lips.


Remarks:  Vázquez Riveiros and Patterson (2008) provided their own description of S. biformis:  “ Test free, elongate, narrow, ovoid in section, margins broadly rounded, sides nearly parallel; wall agglutinated, solid; large early planispiral coil of few chambers followed by biserially arranged chambers, coil commonly of greater breadth than the first few parts of the of the biserial chambers, very slightly inflated; sutures somewhat indistinct, only slightly depressed; aperture a low arch at inner margin of final chamber.


Distribution: This species found across Puget Sound and is common across the South Sound embayments.

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