Tolypella iranica R.E. Romanov, V.Yu. Nikulin

Romanov, Roman E., Nikulin, Vyacheslav Yu., Nikulin, Arthur Yu., Zhakova, Liubov V., Ivanov, Stepan D., Stepanova, Vera A., Efremov, Andrey N. & Gontcharov, Andrey A., 2025, Description of new species Tolypella iranica (Charophyceae, Characeae) and update of the species distribution range of T. mongolica, Phytotaxa 698 (1), pp. 1-14 : 3-8

Tolypella iranica R.E. Romanov, V.Yu. Nikulin et A.A. Gontcharov sp. nov.

Diagnosis:— Tolypella iranica sp. nov. differs from all dioecious species of Tolypella , T.hispanica Nordst. ex Allen (1888: 51) , T. mongolica , and T. porteri ( Daily 1954: 144) R.E. Romanov in Romanov et al. (2024: 33) with rbc L and ITS sequences. Tolypella iranica sp. nov. differs from T. porteri by the shape of branchlet end cells: they are not reduced and not sharply narrower than penultimate cells. Tolypella iranica sp. nov. differs from T. mongolica by the presence of 4-celled endings of branchlet axi, the absence of 2-celled lateral rays of branchlets, much less abundant oogonia in their clusters at branchlet nodes, the presence of oogonia at branchlet nodes mostly, and the presence of male plants; but it is unclear if T. mongolica is parthenogenetic. Tolypella iranica sp. nov. differs from T. hispanica and T. porteri by antheridia of only about half of size.

Description ( Figs 1–13 ):—The plants are evidently encrusted with lime, up to 22 cm long. Male and female plants do not differ in general appearance and morphological vegetative traits in a pressed state ( Figs 1–13 ). The basal axial internode is the longest and axial internodes are gradually shortened towards the apex. The plants are mainly branched at the lowest nodes of the main axis. The branchlets are ca. 10 in a whorl or less in whorls more distant from the plant base ( Fig. 2 ). The basal internodes of branchlets are more or less shortened resulting in the formation of fertile heads having mostly long end parts of branchlets extending from condensed parts of whorls ( Figs 1–8 ). Terminal heads with short branchlets overlapping above axis tips and undeveloped tiny terminal heads placed at branches shorter of branchlets of the same stem node are notable too ( Fig. 8 ). The branchlets of male and female plants are monopodial. They have only a single node at the branchlet axis each. The nodes bear three lateral rays. The lateral rays are 3-celled. They are always distinctly shorter than the branchlet axis, but always longer than oogonia and antheridia, sometimes only slightly longer than oogonia ( Figs 2–7, 9–11 ). The additional fertile lateral rays in branchlet nodes can be formed too ( Fig. 13 ). They have a single fertile node each bearing a few subsequent short lateral rays. The end parts of the axi of branchlets are 3–4-celled, consisting of cells gradually shortening from the basal one. The whole branchlet axi, and lateral rays gradually narrow to the ends. End cells of branchlets somewhat narrow to rounded tips. Oogonia are sessile and shortly stalked, solitary to clustered at branchlet nodes and outside of bases of branchlet whorls but formed at branchlet nodes in most cases. Only unripe oogonia were observed despite well-developed plants. Ripe oospores are missing. Antheridia are situated outside of bases of branchlets whorls and at the basal nodes of branchlets, but mainly formed at branchlet nodes. They appear sessile in a pressed state. Antheridia are mostly clustered ( Figs 5, 7, 9–11 ). They frequently appear as triplicate in branchlet nodes. They are unevenly ripe at the same node. The diameter of antheridia is 250–366 μm in dry state.

Holotype (designated here):— LE A0006281 .

Isotype (designated here):— W 0174492.

Representative DNA sequences for LE: — rbc L gene ( PV 067678), ITS region ( PV 062064).

Type locality: — IRAN, ditches nearby Isfahan. The map of the route by Haussknecht is available in Hellwig et al. (2025).

Etymology: —This species was named to highlight the country where its type locality is situated.

Distribution: — Tolypella iranica is known from one old locality in the center of Iran.

Habitat: —According to the laconic label of the holotype, this species was collected from ditches, i.e. from shallow water bodies in arid environment.

Short description of specimens of T. mongolica from Kazakhstan and the West Siberian Plain

The plants are unincrusted with calcite.They have the same combination of morphological traits known for T.mongolica , including abundant oogonia at whorl bases and branchlet nodes, more or less gradually tapering branchlets with no tiny end cells, 2–3-celled lateral rays of branchlets, and 2–3-celled ends of branchlet axi ( Figs 14–23 ). The calcification of oospores and formation of gyrogonites are lacking. Oospores of plants from Kazakhstan are dark brown, widely ellipsoid and indistinctly obovate, 250–296 μm long, 248–258 μm wide, with 6 or 7 flanged ribs forming fence-like flanges around basal plates ( Figs 24–29 ). Fossae are 37–63 μm wide. The surface of fossae is sparsely tuberculate with variable density and prominence of tubercles even within the same oospore.

Phylogenetic analyses

Phylogenetic analyses of 47 rbc L sequences of Characeae placed T. iranica as a sister species to T. mongolica (100/1.00, Fig. 30 ). These species, along with T. porteri (2 genotypes, Supplementary Table 1), formed a weakly supported clade (74/–). The remaining species in the genus ( T. glomerata , T. nidifica (O.F. Müller 1782: t. 761) A. Braun (1857: 344), T. normaniana (Nordst. in Norman 1868: 334) Nordstedt (1889: 15), T. salina Corillion (1960: 198) , T. hispanica ) did not form distinct clades. Four common haplotypes were identified in the phylogenetic tree ( Fig. 30 ). Two well-supported clades (100/1.00) were recovered for Sawia and Sphaerochara .

The ITS-based phylogeny ( Fig. 31 ) supports the rbc L tree, with T. iranica clustering closely with T. mongolica (100/1.00) and T. porteri (69/0.98) within the genus Tolypella . However, these species are only topologically separated, and this clade lacks strong statistical support.

Figures

FIGURE 1. Holotype of Tolypella iranica (LE A0006281) containing both female and male plants. Scanned image by V.A. Stepanova.

FIGURES 2–13. Morphological traits of male and female plants from holotype of Tolypella iranica (LE A0006281): 2–4, 6, 13—female plants; 5, 7–11—male plants; 2—base of branchlet whorl (arrowhead) with numerous branchlets; 3—bases of branchlet whorl (double arrowheads) with not greatly shortened basal segments of branchlets, arrowheads indicate branchlet nodes; 4 & 5—complete whorls of branchlets, arrowheads indicate axial nodes (4) and end part of branchlet axis (5); 6—apical part of axis, arrowhead indicated axial node; 7—lax whorl of branchlets, arrowheads indicate clustered antheridia; 8—apical head; 9—base of branchlet whorl, arrowhead indicates ends of branchlet axes, double arrowhead indicates lateral rays without nodes; 10 & 11—closer view of fertile branchlets with the antheridia flattened during pressing (double arrowheads); 12—base of branchlet whorl (arrowhead) with short basal segments of branchlets and unripe poorly recognizable gametangia; 13—decalcified rewetted fragment showing 4-celled end of axis of branchlet (arrowhead) and presence of node at lateral ray of branchlet (double arrowhead). Scale: 2–8—2 mm, 9–13—1 mm. Photographs 2–12 by S.D. Ivanov, 13 by R.E. Romanov.

FIGURE 30. ML phylogenetic tree of Characeae (model TIM3+I+G) showing the position of the new species based on rbcL sequence data (47 sequences, 1354 aligned positions). Supports [(BP)> 50% and (PP)> 0.95: ML/BI] are provided above/below the branches. Branches received 100% BP and 1.00 PP support marked by asterisk. The newly obtained sequences of Tolypella iranica sp. nov. are shown in bold. Sequences of the different species carrying one genotype are marked with grey.

FIGURE 31. Unrooted ML-tree of Tolypella sensu lato (model TIM1+G) showing the position of the new species based on ITS rDNA sequence data (16 sequences, 875 aligned positions). See Fig. 30 legend for details.

FIGURES 14–23. Morphological traits of female plants of Tolypella mongolica from the West Siberian Plain (LE): 14–17—upper parts with different number of oogonia at base of branchlet whorls (arrowheads) and single nodes of branchlets, basal segments of branchlets are short; 18, 19—branchlet whorls having 2-celled (arrowheads) and 3-celled end parts of branchlet axi (double arrowheads); 20— branchlet whorl with 2-celled lateral ray (arrowhead) having node and 3-celled end parts of branchlet axi (double arrowheads); 21—base of branchlet whorl with abundant oogonia at branchlet whorl base (arrowhead) and branchlet node (double arrowhead), 3-celled lateral ray is visible at the node indicated with double arrowhead; 22, 23—more or less gradually tapering 3-celled end parts of branchlet axi. Scale: 14–17—2 mm, 18–21—1 mm, 22, 23—0.5 mm. Photographs by R.E. Romanov.

FIGURES 24–29. Oospores of Tolypella mongolica from Kazakhstan (LE), scanning electron microscopy: 24–26—lateral views of oospores; 25–27—surface of oospores. Scale: 24–26—50 μm, 27 & 28—20 μm, 29—10 μm. Photographs by R.E. Romanov.