Caloneis quilinensis Frenguelli, 1937

Sunesen, Ines, Tardivo Kubis, Jonas A. & Sar, Eugenia A., 2017, A re-investigation of three Frenguelli’s Caloneis taxa (Pinnulariaceae, Bacillariophyta) from Argentina, Phytotaxa 305 (3), pp. 165-178 : 172

Caloneis quilinensis Frenguelli (slides of series #310 and associated unmounted material) ( Figs 16–54 , Table 1)

Specimens observed were slightly shorter and narrower and had a higher stria density than those described in the protologue of Frenguelli in Frenguelli & Cordini (1937: 96) ( Table 1). They all have rectangular frustules, with rounded, obliquely reinforced corners, almost always lying in girdle view, 8–18 μm in depth (n = 49) ( Figs 16–25 , 37, 42 ). The valves are linear-elliptic to linear-panduriform with a triundulated margin; the central undulation is slightly narrower than the distal undulations and the apices are cuneate to broadly apiculate ( Figs 29–36 , 50, 51 ). Valve length 39–81 μm (n = 95), valve width 7.5–16.0 μm (n = 25). The valve face is flat, narrow, gently depressed in the central area and slightly raised toward the poles ( Figs 38, 39 , 50, 51 ), merging gently into a deep mantle. The valve mantle, with a curved proximal region and a vertical distal region, is deep, much shallower near the apices, and mostly unperforated ( Figs 26–28 , 40, 48, 49 , 52 ). The overlap between the valve mantles forms the figure of a clepsydra ( Figs 18, 19 ). The central nodule is elliptical, asymmetric ( Figs 32, 35 , 53 ). The axial area is fusiform-lanceolate, narrow near the apices and gradually widening toward the central area ( Figs 31, 32 ). The central area is large, forming an asymmetrical, broad fascia ( Figs 29–36 , 45 ). The raphe is filiform, with slightly curved branches deflected in the same direction as the central fissures. The central external raphe fissures are dug out on the central area and end in drop-like pores ( Figs 30–32 , 38, 39, 41, 44 ). The terminal external raphe fissures are deflected in the same direction as a continuous arch to one side of the apex ( Figs 30, 31 , 38, 39, 46 ), and finish close to the margin of the mantle ( Figs 38, 39, 46, 48, 49 , 52 arrowheads). Internally, the raphe is seen as continuous at the central area, slightly undulate near a subtle, asymmetrical, central nodule ( Figs 50, 51, 53 ), and end distally in small helictoglossae ( Fig. 54 , arrowhead). Pseudosepta surrounding both poles are very short ( Figs 50, 54 , arrows). The striae are alveolate, continuing shortly onto the mantle ( Figs 43, 45, 49 ). Each stria has an outer areolate layer, multiseriate (3–4 poroids rows) ( Figs 43, 45–47, 49 ) and an inner ingrowth of silica opening by an elliptical aperture ( Figs 50, 51, 53, 54 ). These apertures are aligned and located at the junction of valve face and mantle ( Figs 50, 51 ). The girdle is composed of two bands. The valvocopulae is open at one pole ( Figs 39, 41, 42, 46–48 ), with one row of elongate poroids in the pars exterior ( Figs 45, 46 ). The copula is wide, segmental, unstructured, occupying the gap left at the pole that close the full circumference of the valve mantle ( Figs 39, 42, 47 , arrows).

Figures

FIGURES 16–28. Caloneis mendosina Frenguelli (emend. Sar & Sunesen) from syntype material of C. quilinesis. LM. Figs 16–25. Frustules in girdle view, note obliquely reinforced corners. Figs 26–28. Valves in lateral view showing deep mantles. Scale bars: 10 μm.

FIGURES 29–36. Caloneis mendosina Frenguelli (emend. Sar & Sunesen) from syntype material of C. quilinesis. LM. Figs 29–33. Valves linear-elliptic with triundulated margin to linear panduriform, note that distal undulations are wider than central undulation. Figs 30–31. The same specimen in different foci. Idem for figures 32–33. Fig. 34. Tilted frustule showing the hypovalve surrounded by the valvocopula. Figs 35–36. Different foci of a valve. Scale bars: 10 μm.

FIGURES 37–49. Caloneis mendosina Frenguelli (emend. Sar & Sunesen) from unmounted syntype material of C. quilinesis. SEM. External views.Arrowheads show terminal raphe fissures and arrows segmental copula. Figs 37–38. Same frustule in connective view and valvar view respectively. Fig. 39. Frustule showing the hypovalve and the epicingulum. Note vertical, unperforated region of the valve mantle of the epivalve, an open valvocopula and a segmental copula, m: mantle, v: valvocopula. Fig. 40. Valve in lateral view showing vertical, unperforated region of the valve mantle, shallower near the apices. Fig. 41. Frustule tilted similar to figure 39. Fig. 42. Frustule in girdle view. Note open valvocopula and segmental copula. Fig. 43. Detail of the figure 39 showing alveolae with outer areolate, multiseriate layer (3–4 poroids rows). Fig. 44. Detail of figure 32 showing central external raphe fissures dug out on the central area, ending in drop-like pores, deflected toward one side of the valve. Fig. 45. Detail of a central area showing alveolate striae of the hypovalve and valvocopula of the epicingulum with a row of elongate poroids. Figs 46–47. Detail of both apices of the valve in figure 39 showing the epicingulum, m: valve mantle, v: open valvocopula, and a segmental copula. Fig. 48. Detail of the polar area of a frustule in figure 41, note external terminal raphe fissure terminates close the valve margin (arrows). Fig. 49. Detail of a polar area of a valve in figure 40 showing the raphe fissure. Note alveolate striae continuing shortly onto the valve mantle. Scale bar: 10 μm in Figs 37–42; 5 μm in Figs 44–47; 2 μm in Figs 43, 48, 49.

FIGURES 50–54. Caloneis mendosina Frenguelli (emend. Sar & Sunesen) from unmounted syntype material of C. quilinesis. SEM. Figs 50–51. Linear-panduriform valves with apiculate apices in internal view. Note the raphe is continuous at the central area and asymmetrical central nodule. Arrows show pseudosepta in figure 50. Fig. 52. Valve in lateral view showing valve mantle. Note terminal external raphe fissure finishing close to the valve margin (arrowhead). Fig. 53. Detail of the central nodule. Fig. 54. Detail of the apex of the valve in figure 51 showing a small helictoglossa (arrowhead) and a short pseudoseptum (arrow). Scale bar: 10 μm in Figs 50–52; 5 μm in Figs 53, 54.