Divergita toxoneides (Castracane) Theriot, 2018

Sabir, J. S. M., Theriot, E. C., Lobban, C. S., Alhebshi, A. M., Al-Malki, A. L., Hajrah, N. H., Khiyami, M. A., Obaid, A. Y., Jansen, R. K. & Ashworth, M. A., 2018, Systematics of araphid diatoms with asymmetric rimoportulae or densely packed virgae, with particular attention to Hyalosynedra (Ulnariaceae, Bacillariophyta), Phytotaxa 347 (1), pp. 1-49 : 21

Divergita toxoneides (Castracane) Theriot comb. nov. ( Figs 49–53 )

Basionym: — Synedra toxoneides Castracane (1880 , 105)

Synonyms: — Hyalosynedra toxoneides (Castracane) Perez-Coca, Chang, Wang and Wang (2017 , 514)

Material studied: —WK57, from the laboratory of WHCF Kooistra, off Ischia, near Naples, Italy ( Medlin et al. 2008, Kooistra et al. 2009).

Description: —The one complete specimen imaged measured 173.6 μm long and 4.4 um wide and was curved along the center line, with margins converging steadily towards the apices ( Fig. 49 ). The ends were subcapitate ( Figs 49–51 ). The external areolar pore pattern was decussate ( Figs 52, 53 ). The internal membrane was perforated by a row of pores, one between each pair of virgae at the face-mantle junction. Virgae were 24–28 in 10 μm. The ocellulimbi were very weakly sunken ( Figs 50, 53 ), about 14 pores wide and 3 pores tall, and without spines. The sternum was broad and lanceolate in shape. A rimoportula occurred at each pole and each was weakly asymmetric. Images provided by Dr. Kooistra did not show girdle bands.

Remarks: —This strain was previously identified and illustrated by SEM in Kooistra et al. (2009). Additional observations reported here include information on the asymmetric rimoportulae, and overall valve shape. Perez-Coca et al. (2017) illustrated deformed specimens identified also as H. toxoneides , based primarily on the similarity of the areolar pattern and the near-identity of SSU sequences (the aligned SSU sequences of Perez-Coca strain AQ10 from coastal Taiwan and Kooistra WK57 from the Mediterranean Sea differ by only two base pairs, one of which is an indel.) Girdle bands in the coastal Taiwan specimens were without pores and open.

Figures

FIGURES 49–53. Divergita toxoneides. SEM micrographs from culture WK57. 49. Whole valve. 50. Interior detail of apex. 51. Interior detail of apex.52.Exterior detail of broad central area of lanceolate sternum.53. Exterior detail of apex showing barely sunken ocellulimbus and decussating areolae.