Dinobryon taiyuanensis X. JIANG, J. FENG & S. XIE., 2019

Jiang, Xiao-Die, Nan, Fang-Ru, Lv, Jun-Ping, Liu, Qi, Xie, Shu-Lian, Kociolek, John Patrick & Feng, Jia, 2019, Dinobryon taiyuanensis (Chrysophyta, Dinobryaceae), a new freshwater species described from Shanxi province, China, Phytotaxa 404 (1), pp. 41-50 : 43-44

Dinobryon taiyuanensis X. JIANG, J. FENG & S. XIE. sp. nov. ( Fig. 2 )

Etymology:— The species epithet refers to the Holotype locality (Linde Lake, Taiyuan City, Shanxi Province, China).

Diagnosis:— Colonies short and narrow, cells with two heterokont flagella, surrounded by a lorica. The lorica resembling a bent or S-shaped cone, narrow and short, 20–28 μm long, 6.5–8.0 μm wide. The pointed part of the lorica forming an oblique cone. The base of the lorica gradually widened. The upper opening of the lorica first constricted, then expanded slightly.

Type:— CHINA, Shanxi province, Linde Lake (37°80’29”N, 112°59’7”E), phytoplankton, collected by Xiaodie Jiang, 16 April 2018 (Holotype: SXU-LD180416; Paratype: LD181416). Deposited in Herbarium of Shanxi University ( SXU), Taiyuan, Shanxi Province, China .

Authentic strain:— SXU-LD180416.

Distance analysis

Pairwise distances based on SSU sequences between the present species and the freshwater Dinobryon taxa worldwide are listed in Table S2. Distance between D. taiyuanensis and the other Dinobryon groups was larger than the intraspecific distance of Dinobryon . For ITS sequence, Distance among D. taiyuanensis and the other Dinobryon groups was larger than the intraspecific distance of Dinobryon (Table S3).

Phylogenetic analysis

The SSU data matrix included 34 Dinobryon strains and 2 outgroup taxa, and consisted of 905 characters, of which 95 (10.4%) were variable and 81 (8.9%) were parsimony-informative. Conserved sites were 810 (89.5%). The average composition of T, C, A, and G was 27.8%, 17.8%, 28.5% and 25.9%, respectively. The ITS alignment included 29 Dinobryon strains and 2 outgroup taxa, and consisted of 878 characters, of which 417 (47.4%) were variable, 357 (40.6%) were parsimony-informative and 458 (52.1%) were conserved sites. The average composition of T, C, A, and G for all strains was 29.2%, 23.3%, 25.3% and 22.2%, respectively.

Analyses based on SSU sequences ( Table S2, Fig. 3 ) showed that the sequences of all analyzed Dinobryon strains fell into several different clusters. All three methods including Neighbor-joining, Maximum likelihood, Bayesian inference produced similar topologies. Dinobryon species were subdivided into four main lineages with different statistical support. The D. taiyuanensis formed a lineage next to D. sociale var. americanum (Brunnthaler) Bachmann (1911: 54) , D. cylindricum , D. sertularia and D. cf. s ociale (99/1.00/99). Another lineage consisted of D. sociale (94/-/92). The third lineage consisted of D. pediforme (99/0.91/100). The last lineage comprised morphospecies of D. divergens and D. bavaricum (72/0.81/-). D. taiyuanensis was at the basal position and evidently separated from D. cylindricum , D. sertularia and D. sociale var. americanum (51/0.70/-).Analyses based on ITS sequences (Table S3, Fig. 4 ) showed the same pattern, with sequences of all analyzed Dinobryon strains comprising different clusters. Dinobryon species were subdivided into four different main lineages with high statistical support. One lineage consisted of D. sociale (91/0.97/100), a second lineage consisted of D. bavaricum (95/1.00/100), and a third lineage consisted of D. divergens (86/0.98/98). The last lineage consisted of D. pediform (100/1.00/100). D. taiyuanensis formed a clade with D. ningwuensis with low statiscal support (-/0/65/-), and together that was shown to be more closely related to the D. bavaricum + D. divergens clade but with low statistical support.

The congruence between the phylogenetic trees of the two conserved gene regions suggested that D. taiyuanensis was quite different from other species of Dinobryon .

Figures

FIGURE 2. Colonial growth habit and morphological features of D. taiyuanensis. Scale bar 20 μm (a), 10 μm (b). a-b.Vegetative structure of D.taiyuanensis, with lorica details evident in Fig. 2b.

FIGURE 3. ML phylogenetic tree based on SSU sequences from species of Dinobryon. Support values>50% for all analyses are shown on branches as follows: maximum likelihood bootstrap values (ML) / Bayesian posterior probabilities (BA) / Neighbor-joining distance bootstrap (NJ). ‘-’ denotes <50% support for that analyses at that node. The new sequences generated in this study are in black.

FIGURE 4. ML phylogenetic tree based on ITS sequences from species of Dinobryon. Support values>50% for all analyses are shown on branches as follows: maximum likelihood bootstrap values (ML) / Bayesian posterior probabilities (BA) / Neighbor-joining distance bootstrap (NJ). ‘-’ denotes <50% support for that analyses at that node. The new sequences generated in this study are in black.