Lutophila iranica S.Kheiri, Edlund, S.A.Spauld. & C.N.Solak

Kheiri, Somayyeh, Edlund, Mark B., Spaulding, Sarah, Solak, Cüneyt Nadir, Sabouri, Jafar, Izadi, Bahman & Peszek, Łukasz, 2024, Lutophila gen. nov., a new diatom genus from the hottest place on Earth, Lut Desert, Iran, Phytotaxa 641 (2), pp. 99-111 : 104-107

Lutophila iranica S.Kheiri, Edlund, S.A.Spauld. & C.N.Solak sp. nov. ( Figs 5–22 , Figs 41–48 )

Registration: http://phycobank.org/104472

Type: — IRAN, Lut Desert , Central Lut , Artificial Lake in the Gojar Depression , 31˚ 00’ 21” N, 58˚ 06’ 56” E, epipelon, collected August 2014, B. Izadi, sample LutB ( ANSP GC-38128 , circled specimen, holotype! designated here (= Fig. 6 ), prepared from material ANSP GCM-22024 ; SMM-MBE2561a, circled specimen, isotype 1! designated here (= Fig. 8 ), prepared from material in the Science Museum of Minnesota SMM-MBE2561a; TARI slide DIA31-01 and material DIA31 , isotype 2!)

Paratype 1: — IRAN, Lut Desert , Central Lut , Gandom Beryan , the Kale-Shoor River , 31° 00ˊ 31˝N, 57° 37ˊ 48˝E, epipelon, collected July 2010, B. Izadi, sample Iran-Lut ( ANSP GC-38129 , circled specimen (= Figs 13–22 ), prepared from material ANSP GCM-22025 ; TARI slide DIA33-01 and prepared from material in the Research institute of Forests and Rangelands DIA33 ; Science Museum of Minnesota slide and material SMM-MBE2562a) .

Paratype 2: — IRAN, Lut Desert, Central Lut, northwest of Kaluts, the Kale-Shoor River, 30˚ 53’ 08.70´´N, 57˚ 53’ 40.77´E, epipelon and epilithon, collected December 2018, S. Kheiri, Sample LutC ( TARI slide DIA 32-02, prepared from material in the Research institute of Forests and Rangelands DIA 32)

Lutophila iranica populations exhibit some morphological variation, which we describe and illustrate as different morphotypes noting that Morphotype 2 tends to be slightly broader, generally more coarsely striated, and with a more defined central area than Morphotype 1.

Morphotype 1 (iranica):Valves linear, symmetric on apical and transapical axes, strongly parallel sides with broadly rounded apices ( Figs 5–9 ). In girdle view, alightly asymmetric along pervalvar axis with a slightly broader mantle on one side of valve ( Fig. 44 ). Valves 8.4–18.4 µm long and 1.6–2.3 µm wide ( Figs 5–9 ). Central area round, very small. Axial area symmetric and very narrow. Raphe straight externally, proximal raphe ends straight and terminal raphe ends deflected unilaterally. Internally the raphe is very slightly curved with proximal raphe ends straight and terminal raphe ends ending in small helictoglossae. Striae parallel, 24–30 in 10 µm; each striae composed of two macroareolae; one macroareola on the valve face and one on the valve mantle. Each macroareola transapically elongate, macroareolae on valve face apically aligned, macroareolae on valve mantle also apically aligned; internal occlusions of macroareolae foriculate, external occlusions of macroareolae hymenate ( Figs 41–48 ).

Morphotype 2 (thermotolerans): Valves linear, symmetric on apical and transapical axes, strongly parallel sides with broadly rounded apices. In girdle view, symmetric along pervalvar axis. Valves 9.6–25.2 µm long and 2.2–3.7 µm wide ( Figs 23–40 ). Central area hardly distinguishable from the axial area. Axial area symmetric. Raphe straight externally, terminal raphe ends curved to the same side of the valve and proximal raphe ends straight. Internally raphe slightly curved with proximal raphe ends slightly deflected unilaterally and terminal raphe ends ending in small helictoglossae. Striae parallel, 24–26(27) in 10 µm; each stria composed of two macroareolae, one macroareola on the valve face and one on the valve mantle. Each macroareola transapically elongate, areolae on valve face apically aligned, areolae on valve mantle also apically aligned; internal occlusions of macroareolae foriculate, external occlusions of areolae hymenate ( Figs 49–56 ). Slides with marked specimens and example populations of Morphotype 2 include those from sample LutB [slide ANSP GC-38128, circled specimen ( Fig. 26 ), prepared from material ANSP GCM-22024; SMM-MBE2561a, circled specimen ( Fig. 27 ), prepared from material in the Science Museum of Minnesota SMM-MBE2561a; and populations on TARI slide DIA31-01 from material DIA31]. Other populations exhibiting Morphotype 2 were found and illustrated from the Kale-Shoor River paratype samples [Sample “Iran-Lut “ ANSP GC-38129, Morphotype 2 specimens ( Figs 31–40 ), from material ANSP GCM-22025; also TARI slide DIA33-01 and prepared from material in the Research institute of Forests and Rangelands DIA33; Science Museum of Minnesota slide and material SMM-MBE2562a; and from sample LutC (TARI slide DIA32-01, prepared from material in the Research institute of Forests and Rangelands DIA32)].

Etymology: —Specific epithet refers to this taxon’s country of origin, Iran.

Distribution of Morphotypes 1 and 2: —Both Morphotypes 1 and 2 were observed only from localities in the Lut Desert, Table 1 . Conditions at the time of type collection (site LutB) included pH of 7.52, conductivity of 323.4 (mS/cm), organic carbon with the concentration of 390 (mg/L), COD of 70.78 (mg/L), silica with the concentration of 349 (mg/L), anions including nitrate (348.7 mg /L), sulfate (1968 mg /L), phosphate (1.17 mg /L), total phosphorus (2.68 mg /L), chloride (75685 mg /L), and cations including potassium (35.5 mg /L), sodium (1417.8 mg /L), calcium (727.27mg /L) and total hardness of 19400 mg /L. XRD analysis indicated that the main salt minerals were gypsum and halites. Physicochemical factors measured at the paratype location (site LutC) included water temperature (20°C), pH (8.5), conductivity (120.6 mS/cm), chloride (10508 mg /L), calcium (2876 mg /L), magnesium (1824 mg /L). There are some differences in the distribution of morphotypes among samples analyzed; Morphotype 1 is more prevalent in sample Iran-Lut, whereas Morphotype 2 is more prevalent in sample LutB.

Differential diagnosis of morphotypes: —Although found together in many Lut Desert collections, the two Lutophila iranica morphotypes differ slightly in size, pervalvar symmetry, striae density, and relative size of the central area. The overall size difference between the two morphotypes is that L. iranica Morphotype 2 has wider and slightly longer valves compared to L. iranica morphotype 1 as evidenced by slightly different size diminution patterns ( Fig. 57 ). Furthermore, L. iranica Morphotype 1 is slightly asymmetric in pervalvar view as one valve mantle is slightly broader ( Fig. 45 ), and L. iranica Morphotype 2 possesses a smaller central area than L. iranica Morphotype 1.

Associated taxa: —There are few other diatom taxa present in these samples. We found other halophilic species at low abundance including Seminavis cf. ostenfeldii (Hustedt) Clavero & Hernández-Mariné , Nitzschia cf. thermaloides Hustedt / ovalis H.J.Arnott, Halamphora cf. borealis (Kützing) Levkov , Halamphora cf. tenerrima (Aleem & Hustedt) Levkov / subsalina Levkov and an unidentified Proschkinia sp. All of these taxa have some uncertainty in their affinities, and we will treat them in greater detail in additional publications.

Figures

FIGURE 57. Variation in valve length and width for the two new species of Lutophila (L. iranica Morphotype 1—black; L. iranica Morphotype 2—grey).

FIGURES 5–40. LM micrographs of Lutophila iranica and the morphotypes from the Central Lut Desert. Figs 5–12. Type population of L. iranica Morphotype 1. Figs 5–9. Valve views of L. iranica Morphotype 1. Fig. 6. L. iranica Morphotype 1 holotype specimen ANSP GC-38128. Fig. 8. L. iranica Morphotype 1 isotype specimen SMM MBE-2561a. Figs 11–12. Girdle views of L. iranica Morphotype 1. Figs 13–22. Paratype population of L. iranica Morphotype 1. Figs 13–21. Valve view of L. iranica Morphotype 1. Fig. 22. Girdle view of L. iranica Morphotype 1. Figs 23-29. Valve view of L. iranica Morphotype 2. Fig. 26. L. iranica morphotype 2 specimen from ANSP GC-38128. Fig. 27. L. iranica Morphotype 2 specimen from SMM MBE-2561a. Fig. 30. Girdle view of L. iranica Morphotype 2. Figs 31–40. Paratype population of L. iranica Morphotype 2. Figs 31–39. Valve view of L. iranica Morphotype 2. Fig. 40. Girdle view of L. iranica Morphotype 2. Scale bar 10 µm (Fig. 12).

FIGURES 41–48. SEM micrographs of Lutophila iranica Morphotype 1, type material; scale bars as indicated. Figs 41–43. External valve view with hymenate areolation. Fig. 41. Entire frustule. Fig. 42. Central area with proximal raphe endings slightly bent to one side. Fig. 43. Headpole of the valve with distal raphe endings curved. Figs. 44–48. Internal valve view. Fig. 44. Entire valve with simple girdle bands. Fig. 45. Entire valve with striae composed of two rows of macroareolae, one on valve face and one on mantle. Fig. 46. Valve end with straight raphe ending in a small helictoglossum. Fig. 47. Central area with bent proximal raphe endings. Fig. 48. Fraction of the valve in girdle view showing simple girdle band.

FIGURES 49–56. SEM micrographs of Lutophila iranica Morphotype 2, type material, scale bars as indicated.Figs 49–52.External valve view with hymenate areolation. Fig. 49. Entire valve. Fig. 50. Central area with proximal raphe endings straight and slightly expanded. Fig. 51. Headpole of the valve with distal raphe endings curved. Fig. 52. The mantle with foriculate areolae. Figs 53–56. Internal valve view. Fig. 53. Entire valve with striae composed of two rows of macroareolae, one on valve face and one on mantle. Fig. 54. Central area with straight proximal raphe endings. Fig. 55. Valve end showing helictoglossum and expanded terminal raphe end slightly curved. Fig. 56. Valve end showing simple girdle bands.