Tripterion kalamensis Holmes, Nagasawa & Takano, 1993

Frankovich, Thomas A., Ashworth, Matt P., Sullivan, Michael J., Veselá, Jana & Stacy, Nicole I., 2016, Medlinella amphoroidea gen. et sp. nov. (Bacillariophyta) from the neck skin of Loggerhead sea turtles (Caretta caretta), Phytotaxa 272 (2), pp. 101-114 : 108-109

Tripterion kalamensis Holmes, Nagasawa & Takano ( Fig. 31 )

LM morphology: Valve morphometrics are as follows: length 18.5–34.5 μm, maximum width 2.5–5.0 μm, length-to-width ratio 4.9–9.6, n = 78. The transapical striae are radiate in the middle of the valve, 18–24 in 10 μm, n = 30, becoming parallel at the apices, up to 24 in 10 μm near the head pole, up to 32 in 10 μm near the foot pole, n = 30. Our observations of the holotype slide of T. kalamensis , the generitype, revealed that the cingulum is composed of multiple copulae that are open at one end ( Fig. 31 , arrows). This contradicts the original description in Holmes et al. (1993a): “Cingulum consisting of one robust closed band, sometimes two (dividing frustules?), with short septa at each pole and bearing a single row of puncta.” We observed many separated single copulae with very short septa and also separated cingula consisting of at least two copulae. We believe the latter is what Holmes et al. (1993a) referred to as a “ robust ” (our emphasis) “closed band”. We offer the following emended description of cingulum structure in Tripterion kalamensis : the cingulum consists of 2–7 porose copulae per frustule that are open at one end with small septa that extend ca. 1/20 of the valve length from the apices.

Type:— BERING SEA. Specimens from the skin of Phocoenoides dalli (Dall’s porpoise) RCF037-1983, 55° N 174° E, R. W. Holmes, 17 April 1989 (holotype ANSP! GC 64443a, isotype ANSP! GC 64443b).

Figures

FIGURES 31–32. Tripterion kalamensis and T. philoderma. Type populations, LM, specimens in valve view showing valve and frustule shape, size range, and separated copulae. 31. Tripterion kalamensis (holotype slide ANSP! GC64443a), arrows indicate septum on copula (top arrow) and open end of copula (bottom arrow). 32. Tripterion philoderma (holotype slide ANSP! GC17182a), arrows indicate lack of septa in separated copulae. Scale bars = 10 μm.