Tryblionella adducta, D.G.Mann, 1990

Im, Ari & Park, Jong Seong Khim and Jinsoon, 2020, Taxonomy and distribution of two small Tryblionella (Bacillariophyceae) species from the Northeast Asian tidal flats, Journal of Species Research 9 (3), pp. 191-197 : 194

Tryblionella adducta

(Hustedt) D.G. Mann 1990 ( Figs. 2 , 4 )

Reference. Hustedt 1955, p. 43, pl. 15, figs. 21 - 22.

Description. Valves are elliptic-lanceolate with sharply rounded apices with the length of 16.6 - 24 μm and width of 6 - 7.6 μm. The valve face is transapically undulated. Striae are parallel in the middle and slightly radiate towards the ends, 15 - 21 in 10 μm. Fibulae are eccentric, developed along the edge of the valve, 15 - 21 in 10 μm. Areolae are punctuated and resolvable under light microscopy, 15 - 18 in 10 μm.

Taxonomic remarks. Tryblionella adducta is superficially similar to Nitzschia punctata particularly in valve outline and punctate areolae, however the latter has a much larger size and more sparse striae. In the original description of N. punctata by W. Smith (1853), the length of the frustule was ca. 31 - 53 μm (0.012 - 0.021 inch) with striae of 12 in 10 μm (31 in 0.001 inch). Later Cleve and Grunow (1880) have also provided the striae density of the same species as of 7 - 9.5 in 10 μm. In fact, there was a record of T. adducta from the Nakdong Estuary, yet with misidentification of the species as N. punctata var. minor Tempère & Peragallo ( Cho, 1989).

Distribution. In Korea, T. adducta was observed from Gyehwa sandflat of Mangyeong-Dongjin River Estuary and Myoengji sandflat of Nakdong River Estuary. In the present study T. adducta was observed from 10 locations along the Chinese coast of the Yellow Sea ( Fig. 1 ). Considering the fact that T. adducta was also reported from mudflats in Ariake Sea, Japan (Ohstuka, 2005; Park et al., 2012a), it is likely that the species is widespread along the coasts of Northeast Asia.

Figures

Fig. 2. Light microscope photographs of Tryblionella adducta from Korea (a-d) and China (e-u). Scale bar=10μm.

Fig. 4. Scanning electron microscope photographs of two newly recorded species. (a-d) Tryblionella adducta (a: external view of the whole valve, b: external view of the valve apex with slightly radiating striae, c: internal view of the whole valve, d: internal valve of valve apex with conspicuous fibulae); (e, f) Tryblionella hyalina (e: internal view of the whole valve, f: internal view of valve apex).

Fig. 1. Map showing the sampling locations along the coasts of the Yellow Sea where Tryblionella adducta and T. hyalina were observed.