taxonID	type	description	language	source
03B5D979FFABF116998EFF0E5A56FE9C.taxon	description	Figs. 1 – 3; 7 A – 7 C, 38 A; 39 A; 40 A, 40 G, 40 Q.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFABF116998EFF0E5A56FE9C.taxon	materials_examined	Type locality. Lake Baikal, shallow water at the Selenga River estuary, north of Posol’skoye Village (approximate coordinates 52 º 02 ’ 39.13 ” N, 106 º 09 ’ 59.48 ” E; hereinafter approximate coordinates are given as the central point of the locality) or opposite Severnaya channel (approximate coordinates 52 º 25 ’ 28.52 ” N, 106 º 32 ’ 15.17 ” E). Type material. Lectotype No. O 10 (female) and paralectotype No. 1 (male): dwm No. O 1 - 080671. Paralectotypes Nos. 2 – 4 (3 females): dwm No. O 2 - 080671. Paralectotypes Nos. 5 – 8 (4 males): dwm No. O 3 - 080671. Paralectotypes Nos. 9 – 16 (4 females; 4 males): swm No. 17. Paralectotype No. 17 (female): swm No. 17 (valves) and wm No. O 4 - 080671 (limbs). Paralectotype No. 18 (female): swm No. 17 (valves) and wm No. O 5 - 080671 (limbs). Paralectotype No. 19 (male): swm No. 17 (valves) and wm No. O 6 - 080671 (limbs). Paralectotype No. 20 (male): swm No. 17 (valves) and wm No. O 7 - 080671 (limbs). All ostracods were collected in Lake Baikal, in shallow water at the Selenga River estuary, in one of two locations: 1) opposite Severnaya channel, June 8, 1971, depth 55 m, gray silt; 2) north of Posol’skoye Village, July 12, 1974, depth 50 m, silt with sand, sample No. 695 from the collection of taxocoenoses of G. F. Mazepova. Since all specimens were in one tube with a common label, we did not determine where each particular specimen was collected from.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFABF116998EFF0E5A56FE9C.taxon	description	Description. Female. Carapace (Figs. 1 A – 1 D; 2 A – 2 F; 39 A) laterally rounded-ovate: L = 1145 – 1220 µm (mean 1175 µm, n = 10), largest H = 860 – 930 µm (mean 895 µm, n = 10), situated slightly posterior to anterior 1 / 3 of L. Dorsal margin slightly arcuate at center. Anterior end of carapace broadly rounded; posterior end more narrowly rounded. Central parts of ventral margin of both valves almost equally concave on inner side and arcuate on outer side. LV slightly overlaps RV in anterior and posterior parts of dorsal margin (in other parts valves are identical). Inner lamella broad. Marginal pore canals long, occupying 100 % of width of inner lamella and ending in sensilla. Inner lamella of each valve with 24 – 25 marginal pore canals. Pore canals of outer lamella opening with branching group sieve pores (up to six canals in group), single near margin of valves; each canal ending in one sensillum. Outer lamella of each valve with 245 – 250 pore canals (here and in the following descriptions a minimal but accurately detected number of canals is given, their complete count is extremely difficult). Inner side of each valve with about 50 – 55 canal apertures. Hinge teeth on RV, relatively narrow and elongated, weakly crenulated, not extending beyond margin of valve; bar on LV, weakly crenulated. Microrelief of valve surface homogeneous, with numerous small rounded pits, differing in diameter by 2 – 3 times (Fig. 7 A – 7 C). Site of greatest carapace width on ventral and dorsal views weakly pronounced and located in central part of carapace (Fig. 2 C, 2 D). A 1, A 2, Md, Mxl, L 5 – L 7 as in Cytherissa heckyi Alekseeva, Krivorotkin et Timoshkin, 2025, but distal segments of L 5 partially fused (almost as in Cytherissa pennata Mazepova, 1990). Male. Carapace (Figs. 1 E – 1 H; 3 A – 3 F; 39 A) slightly longer and lower than in female: L = 1205 – 1250 µm (mean 1225 µm, n = 10), greatest H = 830 – 885 µm (mean 855 µm, n = 10). In dorsal and ventral views, males (Fig. 3 C, 3 D) significantly narrower than females (Fig. 2 C, 2 D), site of greatest width slightly shifted toward posterior 1 / 3 L. Dorsal margin of male valves slightly straighter. Geniculate (transformed) legs on right side of body. Other morphological features of carapace structure, microrelief (Fig. 7 A), A 1, A 2, Md, Mxl, left (nongeniculate) legs L 5 and L 6 as in female; distal segments of nongeniculate L 5 partially fused (Fig. 40 A). Both legs of L 7 and right (geniculate) L 5 as in male C. heckyi. L 6. Right leg (Fig. 40 G). Protopod with four setae and several groups of pseudochaetae (at least four). Endopod two-segmented. First segment with very small seta. Distal part of second segment with small pointed outgrowth. Hemipenis (Fig. 38 A) large, elongate-triangular; outer appendage long, with smoothly curved main axis, almost saber-shaped. Length of hemipenis in quiescent state 620 µm (n = 1), greatest width 395 µm. Diameter of copulatory process 180 – 200 µm. Brush organ (Fig. 40 Q). Both rami with 24 apical setae, row of small pseudochaetae in medial part, row of pseudochaetae in subapical part and barely visible row of pseudochaetae in apical part.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFABF116998EFF0E5A56FE9C.taxon	diagnosis	Differential diagnosis. Owing to the round shell outline in the lateral view, C. glomerata specimens are well distinguished from other Baikal species of the genus. They slightly resemble Cytherissa dextima Mazepova, 1990, but have a quite different pattern of valve overlap (almost equal in C. glomerata, and in C. dextima the left valve is notably larger than the right one), microrelief (C. glomerata has numerous fine pits, C. dextima — large cells) and an average carapace size (C. glomerata: female: L = 1175 µm; H = 895 µm; male: L = 1225 µm; H = 855 µm; C. dextima: female: L = 765 µm; H = 495 µm; male: L = 800 µm; H = 490 µm).	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFABF116998EFF0E5A56FE9C.taxon	discussion	Notes. Besides a list of type specimens published earlier (Mazepova 2001), we have a handwritten catalog by G. F. Mazepova, on which her publication was based. Each tube with a species was supplied by a brief label showing the number of specimens and sample number from G. F. Mazepova’s collection of taxocoenoses. Unfortunately, in some cases all three versions (the published list, handwritten catalog and label) either differ from each other or have different numbers of specimens inside the tube. Therefore, we had to examine every case in detail. For instance, the list of type specimens of C. glomerata (Mazepova 2001: pp. 543) indicates that the collection contains 22 paratypes (11 females and 11 males). The list written by hand of Prof. G. F. Mazepova contains 21 type specimens (10 females and 11 males). The label on the tube also has 21 specimens (10 females and 11 males) that we studied. When describing most of endemic Baikalian ostracods, G. F. Mazepova did not indicate holotypes, and the paratypes (Mazepova 2001) are not valid without a holotype indication. According to article 73.2 of the International Code of Zoological Nomenclature (1999) — hereinafter, ICZN, they should be regarded syntypes that was implemented in this work.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFABF116998EFF0E5A56FE9C.taxon	distribution	Geographic distribution. Endemic to Lake Baikal, found in the northern and southern basins at depths of 21 – 1300 m (for details see Mazepova 1990: p. 323). Inhabits silty sand and silt.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFAFF119998EFE1E5B67FE9C.taxon	description	Figs. 4 – 6; 7 D – 7 F, 38 B; 39 B; 40 C, 40 K.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFAFF119998EFE1E5B67FE9C.taxon	materials_examined	Type locality. Lake Baikal, shallow water at the Selenga River estuary, more precise location unknown (approximate coordinates 52 º 22 ’ 26.11 ” N, 106 º 22 ’ 9.74 ” E). Type material. Neotype No. O 1 (female): dwm No. O 37 - 300771. Additional material. Specimen No. 1 (male): dwm No. O 37 - 300771. Specimens Nos. 2 – 4 (3 females): dwm No. O 38 - 300771. Specimen No. 5 (female): dwm No. O 38 - 300771 (valves) and wm No. O 40 - 300771 (limbs). Specimens Nos. 6 – 10 (5 males): dwm No. O 39 - 300771. Specimen No. 11 (male): dwm No. O 39 - 300771 (valves) and wm No. O 41 - 300771 (limbs). Specimens Nos. 12 – 19 (4 females; 4 males): swm No. 12. Specimen No. 20 (female): swm No. 12 (valves) and wm No. O 42 - 300771 (limbs). Specimen No. 21 (male): swm No. 12 (valves) and wm No. O 43 - 300771 (limbs). All ostracods were collected in shallow water at the Selenga River estuary, July 30, 1971, depth 8 m, silty sand with macrophytes, sample No. 320 from the collection of taxocoenoses of G. F. Mazepova.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFAFF119998EFE1E5B67FE9C.taxon	description	Description. Female. Carapace (Figs. 4 A – 4 D; 5 A – 5 F; 39 B) laterally elongate-ovate: L = 1010 – 1060 µm (mean 1035 µm, n = 10), largest H = 600 – 645 µm (mean 625 µm, n = 10), located on posterior border of anterior 1 / 3 L. Dorsal margins of valves slightly arched at center. Anterior end of carapace broadly rounded, posterior end almost straight, narrowly rounded. Ventral margins of both valves equally concave on inner side and arcuately curved on outer side. LV overlaps RV on dorsal margin. Inner lamella relatively narrow. Marginal pore canals may be long, occupy 100 % of width of inner lamella, or open earlier. Inner lamella of each valve with 36 – 39 marginal pore canals (22 long and 15 – 17 short). Pore canals of outer lamella sieve-type, branching, grouped (up to six canals in group), near margin of valves single; each canal with one sensillum (Fig. 7 E). Outer lamella of each valve with 250 – 290 pore canals. Inner side of each valve with 60 – 70 canal apertures. Hinge teeth on RV, weakly crenulated, not extending beyond margin of valve; bar on LV, weakly crenulated. Microrelief of valve surface heterogeneous, with different diameter round and oval shallow pits (Fig. 7 D, 7 F) covering whole carapace except smooth dorsal margin. Site of greatest carapace width on ventral and dorsal views is at posterior border 3 / 4 L (Fig. 5 C, 5 D). A 1, A 2, Md, Mxl, L 5 – L 7 as in female C. heckyi, but distal segments of L 5 partially fused. Male. Carapace (Figs. 4 E – 4 H; 6 A – 6 F; 39 B) slightly longer and lower than in female: L = 1045 – 1150 µm (mean 1120 µm, n = 10), H = 580 – 640 µm (mean 610 µm, n = 10). In dorsal and ventral views, males (Fig. 6 C, 6 D) distinctly narrower than females (Fig. 5 C, 5 D), site of greatest width weaklier pronounced and located slightly posterior to 3 / 4 L. Posterior margin of carapace rounded. Geniculate (transformed) legs on right side of body. Other morphological features of carapace structure, microrelief, A 1, A 2, Md, Mxl, left (non-geniculate) legs L 5 (Fig. 40 C) and L 6 as in female. Both legs L 7 and right (geniculate) leg L 5 as in male C. heckyi. L 6. Right leg. Protopod with four setae and several groups of pseudochaetae. Endopod two-segmented (Fig. 40 K); first segment with small seta; distal part of second segment with pointed outgrowth. Hemipenis (Fig. 38 B) large, triangular; outer appendage in form of broad robust triangle with slightly curved tip. Length of hemipenis in quiescent state 495 µm (n = 1), greatest width 375 µm. Diameter of copulatory process 235 µm. Brush organ. Both rami with 13 apical setae, row of small pseudochaetae in medial part, row of pseudochaetae in subapical part and barely visible row of pseudochaetae in apical part.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFAFF119998EFE1E5B67FE9C.taxon	diagnosis	Differential diagnosis. The shells of C. dubitabilis specimens on the lateral and dorsal views slightly resemble Cytherissa elongata elongata Bronstein, 1947. The species are distinguished by the shell outlines in lateral view (notably more assymentrical in C. dubitabilis), location of wedge-shaped constriction in dorsal view in females (C. dubitabilis in posterior part, C. elongata elongata in anterior part of the body), size (C. dubitabilis, female: L = 1135 µm; H = 625 µm; male: L = 1120 µm; H = 610 µm; C. elongata elongata, female: L = 850 µm; H = 450 µm; male: L = 955 µm; H = 460 µm).	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFAFF119998EFE1E5B67FE9C.taxon	discussion	Notes. The species was initially described by Z. S. Bronstein as Cytherissa lacustris var. dubitabilis Bronstein, 1947. In 1990, G. F. Mazepova pointed out that the specimens of this taxon were remarkably distinguished from Cytherissa lacustris (Sars, 1863) by the carapace morphology and defined it as a separate species — Cytherissa dubitabilis Bronstein, 1947. In the work of Meisch et al. (2024), we find the species name: Cytherissa dubitabilis (Bronstein, 1947) Martens & Savatenalinton 2011. Z. S Bronstein (1930; 1947) did not separate type series of Baikal ostracods. G. F. Mazepova (1990) indicated syntypes of C. dubitabilis species (Mazepova 2001: pp. 541). The sample these “ syntypes ” were taken from, was collected only in 1971, i. e. in 24 years after the publication of the original description (Z. S. Bronstein collected the samples for the description from about 1927 – 1928). Thus, the specimens from the collection cannot be syntypes according to ICZN (1999). Therefore, we isolate a neotype based on G. F. Mazepova’s specimens.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFAFF119998EFE1E5B67FE9C.taxon	distribution	Geographic distribution. Endemic to Lake Baikal, found in all basins and in the Maloye More Strait at depths from 2 to 95 m (for details see Mazepova 1990: p. 309). Inhabits sands, rarely algae thickets and stones.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFA2F11D998EFF0E5A79F831.taxon	description	Figs. 8 – 11; 38 C; 39 C; 40 F, 40 J.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFA2F11D998EFF0E5A79F831.taxon	materials_examined	Type locality. Lake Baikal, one of two locations: 1) shallow water at the Selenga River estuary, precise location unknown (approximate coordinates 52 º 22 ’ 26.11 ” N, 106 º 22 ’ 09.74 ” E); 2) shallow water at the Selenga River estuary, opposite Sukhaya Village (approximate coordinates 52 º 33 ’ 49.79 ” N, 107 º 04 ’ 34.76 ” E). Type material. Lectotype No. 11 (female) and paralectotype No. 1 (male): dwm No. O 1 - 090671. Paralectotypes Nos. 2 – 7 (6 females): dwm No. O 2 - 090671. Paralectotypes Nos. 8 – 10 (3 males): dwm No. O 3 - 090671. Paralectotype No. 11 (male): dwm No. O 3 - 090671 (left valve), swm No. 20 (right valve), and wm No. O 4 - 090671 (limbs). Paralectotypes Nos. 12 – 19 (4 females, 4 males): swm No. 20. Paralectotype No. 20 (female): swm No. 20 (separate body and valves). Paralectotype No. 21 (male): swm No. 20 (separate body and valves). Paralectotype No. 22 (male): swm No. 20 (valves) and wm No. O 5 - 090671 (limbs). Paralectotype No. 23 (female): swm No. 20 (right valves) and wm No. O 6 - 090671 (limbs). Paralectotype No. 24 (female): swm No. 20 (right valves) and wm No. O 7 - 090671 (limbs). All ostracods were collected from one of two locations in Lake Baikal: 1) shallow water at the Selenga River estuary, June 9, 1971, depth 38 m; 2) shallow water at the Selenga River estuary, opposite Sukhaya Village, August 3, 1983, depth 20 m and 50 m, silty sand, sample No. 1076 from the collection of taxocoenoses of G. F. Mazepova. Since all specimens were in one tube with a common label, we did not determine where each specimen was collected from.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFA2F11D998EFF0E5A79F831.taxon	description	Description. Female. Carapace (Figs. 8 A – 8 D; 9 A – 9 F; 39 C) laterally elongate-ovate: L = 620 – 650 µm (mean 635 µm, n = 10), largest H = 380 – 410 µm (mean 400 µm, n = 10), located on posterior border of anterior 1 / 3 L. Dorsal margins of valves slightly arcuate at center. Anterior end of carapace broadly rounded, posterior end almost straight, narrowly rounded near ventral margin. Ventral margins of both valves equally concave on inner side; ventral margin of LV concave on outer side as on inner side, and straight on RV. RV overlaps LV throughout except for anterior margin. Inner lamella broad. Marginal pore canals long, occupying 100 % of inner lamella and ending in sensilla. Inner lamella of each valve with 13 – 23 marginal pore canals. Pore canals of outer lamella sieve-type, branching, grouped (up to four canals in group), single near margin of valves; each canal with one sensillum (Fig. 11 E). Outer lamella of each valve with at least 50 – 65 pore canals. Inner side of each valve with approximately 30 – 35 canal apertures. Hinge teeth on LV, distinctly crenulated; bar on RV, crenulated. Hinge teeth on LV, distinctly crenulated; bar on RV, crenulated. Posterior hinge tooth slightly extending beyond margin of valve. Microrelief of valve surface heterogeneous, consisting of large round pits covering central part of valves (Fig. 11 A); closer to ventral and dorsal margins, pits more smoothed (Fig. 11 C, 11 D). Anterior (Fig. 11 B) and posterior margins of valves almost smooth. Site of greatest width of carapace on ventral and dorsal views located at posterior border of 3 / 4 L (Fig. 9 C, 9 D). In lateral view, site of greatest width remotely resembling rib-shaped protrusion extending from ventral margin to dorsal margin. A 1, A 2, Md, Mxl, L 5 – L 7 as in female C. heckyi. Male. Carapace (Figs. 8 E – 8 H; 10 A – 10 F; 39 C) slightly longer and lower than in female: L = 650 – 680 µm (mean 670 µm, n = 10), greatest H = 380 – 400 µm (mean 390 µm, n = 10). In dorsal and ventral views, males (Fig. 10 C, 10 D) distinctly narrower than females (Fig. 9 C, 9 D), site of greatest width shifted to posterior margin and located at 1 / 8 L. Inner lamella of each valve with 15 pore canals. Outer lamella of each valve with at least 70 – 75 pore canals. Inner side of each valve with approximately 24 – 32 canal apertures. Geniculate (transformed) legs on left side of body. Other morphological features of carapace structure, microrelief, A 1, A 2, Md, Mxl, right (nongeniculate) legs L 5 (Fig. 40 F) and L 6 as in female. Both legs L 7 and left (geniculate) L 5 as in male C. heckyi. L 6. Left leg. Protopod with four setae and several groups of pseudochaetae. Endopod two-segmented (Fig. 40 J). First segment with very small, barely visible seta. Distal part of second segment with gently pointed outgrowth. Hemipenis (Figs. 11 F; 38 C) small, triangular; outer appendage with gradually curved main axis, almost saber-shaped, tip of appendage slightly pointed. Length of hemipenis in quiescent state 310 µm (n = 1), greatest width 220 µm. Diameter of copulatory process 85 – 90 µm. Brush organ. Both rami with 18 apical setae, rows of pseudochaetae in subapical and apical part. Row of pseudochaetae in medial part either very fine or absent.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFA2F11D998EFF0E5A79F831.taxon	diagnosis	Differential diagnosis. By the hinge structure, C. derupta specimens are attributed to the species with teeth on the left valve. Specimens of C. derupta in dorsal and ventral views are elongate-triangular, allowing to clearly distinguish them from other Baikalian species of this genus. These traits of C. derupta make it similar to C. cytheriformis specimens but with obviously different microrelief and carapace size. Notes. The list of type specimens (Mazepova 2001: pp. 554) include 25 individuals: 7 paratypes (6 females and a male) and 18 syntypes (9 females and 9 males). However, the handwritten version of G. F. Mazepova’s catalog of type specimens lists only 14 (9 females and 5 males). The label on the tube indicates 25 types specimens (15 females and 10 males), which we examined. The definition of paratypes is not valid without a holotype (ICZN, 1999), therefore, all specimens are considered syntypes. Geographic distribution. Endemic to Lake Baikal, found in the southern basin, in shallow water at the Selenga River estuary, in the Maloye More Strait, north of the Svyatoy Nos peninsula at depths from 5 to 50 m (for details see Mazepova 1990: p. 401). Lives on sand, once recorded on stones with sponges.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFB9F100998EFF0E5EA7F803.taxon	description	Figs. 12 – 15; 38 E; 39 D; 40 I, 40 S.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFB9F100998EFF0E5EA7F803.taxon	materials_examined	Type locality. Lake Baikal, Maloye More Strait, near Ulan-Baysan Cape (second name Zantyk Cape) (approximate coordinates 53 º 19 ’ 24.92 ” N, 107 º 38 ’ 45.39 ” E). Type material. Neotype No. O 11 (female): dwm No. O 25 - 130868. Additional material. Specimen No. 1 (male): dwm No. O 25 - 130868. Specimens Nos. 2 – 15 (14 females): dwm No. O 26 - 130868. Specimens Nos. 16 – 19 (4 males): dwm No. O 27 - 130868. Specimen No. 20 (male): dwm No. O 27 - 130868 (valves) and wm No. O 28 - 130868 (limbs). Specimens Nos. 21 – 28 (4 females; 4 males): swm No. 19. Specimen No. 29 (male): swm No. 19 (valves) and wm No. O 29 - 130868 (limbs). Specimen No. 30 (female): swm No. 19 (valves) and wm No. O 29 - 130868 (limbs). All ostracods were collected in the Maloye More Strait, near Ulan-Baysan Cape (second name Zantyk Cape), August 13, 1968, depth 10 m, sand with detritus, sample No. 174 from the collection of taxocoenoses of G. F. Mazepova.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFB9F100998EFF0E5EA7F803.taxon	description	Description. Female. Carapace (Figs. 12 A – 12 D; 13 A – 13 F; 39 D) laterally elongate-ovate: L = 935 – 990 µm (mean 965 µm, n = 10), largest H = 520 – 545 µm (mean 535 µm, n = 10), located at posterior border of anterior 1 / 3 L. Dorsal margins of valves slightly arcuate at center. Anterior end of carapace broadly rounded, posterior end almost straight, narrowly rounded. Ventral margins of both valves on inner and outer sides equally concave. RV overlaps LV on dorsal margin. Inner lamella broad. Marginal pore canals may be short and may not reach margin of inner lamella or may occupy 100 % of inner lamella; some marginal pore canals branching, especially in anterior part of valves. Inner lamella of each valve with 36 – 39 marginal pore canals (15 – 17 short, 21 – 22 long). Pore canals of outer lamella sieve-type, branching, grouped (up to seven canals), single near margin of valves; each canal with one sensillum. Outer lamella of each valve with at least 170 – 180 pore canals. Inner side of each valve with about 45 – 47 canal apertures. Hinge teeth on LV, slightly crenulated, not extending beyond margin of valve; bar on RV, crenulated. Microrelief of valve surface heterogeneous, consisting of smoothed shallow circular pits; size of pits decreases towards dorsal and ventral margin (Fig. 15 A – 15 E), dorsal margin of valve almost smooth. Anterior and posterior parts of carapace uneven due to highly smoothed pits (Fig. 15 B). Site of greatest width of carapace on ventral and dorsal views is at posterior border of 3 / 4 L (Fig. 13 C, 13 D). In lateral view, site of greatest width resembling oval protrusion (Fig. 15 C) extending from center of carapace to posterior-ventral corner. A 1, A 2, Md, Mxl, L 5 – L 7 as in C. heckyi, but distal segments of L 5 partially fused. Male. Carapace (Figs. 12 E – 12 H; 14 A – 14 F; 39 D) slightly longer and lower than in female: L = 1015 – 1065 µm (mean 1035 µm, n = 10), H = 495 – 545 µm (mean 515 µm, n = 10). Site of greatest width on dorsal and ventral views shifted slightly beyond posterior 1 / 5 L (Fig. 14 C, 14 D). Outer lamella of each valve with at least 195 – 205 pore canals. Inner side of each valve with approximately 57 – 68 canal apertures. Geniculate (transformed) legs on left side of body. Other morphological features of carapace structure, microrelief (Fig. 15 A, 15 D, 15 F), A 1, A 2, Md, Mxl, right (nongeniculate) legs L 5 and L 6 as in female; distal segments of L 5 partially fused. Both legs of L 7 and left (geniculate) L 5 as in male C. heckyi. L 6. Left leg (Fig. 40 I). Protopod with four setae and several groups of pseudochaetae. Endopod three-segmented. First segment with plumed seta. Distal part of endopod with gently pointed outgrowth. Hemipenis (Fig. 38 E) medium-sized, triangular; outer appendage triangular, slightly widened at tip. Length of hemipenis in quiescent state 395 µm (n = 1), greatest width 305 µm. Diameter of copulatory process 180 µm. Brush organ (Fig. 40 S). Both rami with 10 apical setae, row of small pseudochaetae in medial part, rows of pseudochaetae in subapical and apical parts.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFB9F100998EFF0E5EA7F803.taxon	diagnosis	Differential diagnosis. Similar to the previous species (see differential diagnosis of C. derupta).	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFB9F100998EFF0E5EA7F803.taxon	discussion	Notes. As previously mentioned, Z. S. Bronstein (1930; 1947) did not distinguish type series. G. F. Mazepova identified syntypes of the species C. cytheriformis (Mazepova 2001: pp. 551). While doing this, she isolated the “ syntypes ” from the samples taken only in 1968, i. e. 21 years after the publication of the original description. Therefore, the collection specimens cannot be regarded syntypes according to ICZN (1999). That is why we distinguish a neotype based on Mazepova’s specimens.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFB9F100998EFF0E5EA7F803.taxon	distribution	Geographic distribution. Endemic to Lake Baikal, found in the northern and southern basins, in the Maloye More Strait at depths from 2 to 100 m (for details see Mazepova 1990: p. 381). Inhabits sand, twice recorded on stones.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFBCF107998EFF0E5FB2FE9C.taxon	description	Figs. 16 – 18; 22 A, 22 C, 22 D; 38 F; 39 E; 40 P.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFBCF107998EFF0E5FB2FE9C.taxon	materials_examined	Type locality. Lake Baikal, Angara River source, Listvennichny Bay, Listvyanka Settlement, opposite the building of the Baikal Museum of the Siberian Branch of the Russian Academy of Sciences (approximate coordinates 51 º 52 ’ 03.76 ’’ N, 104 º 49 ’ 50.57 ’’ E). Type material. Lectotype No. O 12 (female) and paralectotype No. 1 (male): dwm No. O 1 - 020368. Paralectotypes Nos. 2 – 6 (5 females): dwm No. O 2 - 020368. Paralectotypes Nos. 7 – 13 (7 males): dwm No. O 3 - 020368. Paralectotypes Nos. 14 – 21 (4 females, 4 males): swm No. 28. Paralectotype No. 22 (female): swm No. 28 (valves). Paralectotype No. 23 (male): swm No. 28 (valves). Paralectotype No. 24 (male): swm No. 28 (valves and limbs). Paralectotype No. 25 (female): swm No. 28 (valves) and wm No. O 4 - 020368 (limbs). Paralectotype No. 26 (male): swm No. 28 (valves) and wm No. O 5 - 020368 (limbs). Paralectotype No. 27 (male): swm No. 28 (valves) and wm No. O 6 - 020368 (limbs). All ostracods were collected near the source of the Angara River, Listvennichny Bay, Listvyanka Settlement, opposite the building of the Baikal Museum, March 2, 1968, depth 3 – 3.5 m, stones, samples Nos. 105 and 106 from the collection of taxocoenoses of G. F. Mazepova.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFBCF107998EFF0E5FB2FE9C.taxon	description	Description. Female. Carapace (Figs. 16 A – 16 D; 17 A – 17 F; 39 E) laterally rectangular-ovate: L = 1015 – 1040 µm (mean 1025 µm, n = 10), largest H = 625 – 650 µm (mean 635 µm, n = 10), located on posterior border of anterior 1 / 3 L. Dorsal margins of valves slightly arcuate at center. Anterior end of carapace broadly rounded, posterior end almost straight, narrowly rounded. Ventral margins of both valves equally concave on inner side. Ventral margin of RV concave on outer side as on inner side, but on LV almost straight, weakly concave. LV slightly overlaps RV throughout except posterior part of ventral margin. Small protrusion at posterior part of ventral margin of RV. Inner lamella broad. Marginal pore canals long, occupying 80 – 100 % of the width of the inner lamella and ending in sensilla. Inner lamella of each valve with 32 – 34 marginal pore canals. Pore canals of outer lamella sieve-type, branching, grouped (up to four canals in a group), single near margin of valves; each canal with one sensillum. Outer lamella of each valve with at least 85 – 90 pore canals. Inner side of each valve with approximately 38 – 44 canal apertures. Teeth of hinge on RV, slightly crenulated, not extending beyond margin of valves; bar on LV, slightly crenulated. Microrelief of valves surface consists of evenly distributed smoothed shallow round pits (Fig. 22 A). Examination of SEM photographs of females and males gives impression that pitted microrelief on LV slightly more pronounced (Figs. 17 B; 18 B), and on RV smoothed (Figs. 17 A; 18 A). Near margins of valves, pits smaller in size. Site of greatest carapace width on ventral and dorsal views weakly pronounced and located in central part of L (Fig. 17 C, 17 D). A 1, A 2, Md (Fig. 22 C), Mxl, L 5 – L 7 as in C. heckyi, but distal segments of L 5 partially fused. Male. Carapace (Figs. 16 E – 16 H; 18 A – 18 F; 39 E) slightly longer and lower than in female: L = 1015 – 1065 µm (mean 1045 µm, n = 10), H = 570 – 625 µm (mean 595 µm, n = 10). Posteroventral protrusion more pronounced than in female, especially on ventral view (Fig. 18 C). Geniculate (transformed) legs on right side of body. Other morphological features of carapace structure, microrelief, A 1, A 2, Md, Mxl, left (non-geniculate) legs L 5 and L 6 as in female; distal segments of L 5 partially fused. Both legs of L 7 and right (geniculate) L 5 as in male C. heckyi. L 6. Right leg. Protopod with four setae and several groups of pseudochaetae. Endopod two-segmented (Fig. 40 P). First segment with seta. Distal part of second segment with gently pointed outgrowth. Hemipenis (Figs 22 D; 38 F) triangular; outer appendage triangular, with pointed tip. Length of hemipenis in quiescent state 505 µm (n = 1), greatest width 325 µm. Diameter of copulatory process 195 – 225 µm. Hemipenis of paralectotype No. 26 (Fig. 38 F) and paralectotype No. 24 (Fig. 22 D) differ slightly in structure of outer appendage, which on whole mount with pointed tip. Brush organ. Both rami with 12 apical setae, row of small pseudochaetae in medial part, rows of pseudochaetae in subapical and apical parts.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFBCF107998EFF0E5FB2FE9C.taxon	diagnosis	Differential diagnosis. The shells of C. golyschkinae and C. obrutshevi are morphologically nearly identical, except for the valve outlines in lateral view and carapace outlines in dorsal and ventral views. The species differ in the segmentation of the distal L 5, L 6 and L 7 segments in females and males: the distal segments of C. golyschkinae are partially fused only on the L 5 (in females and non-geniculate in males), C. obrutshevi has partially fused distal L 5 – L 7 segments in females and non-geniculate L 5 and L 6 in males. Notes. The list of types specimens (Mazepova 2001: pp. 542) includes 28 paratypes (13 females and 15 males) that is in accordance with the handwritten type catalog and the label inside the tube. The designation of paratypes is not valid without the holotypes, hence, all the individuals are syntypes. Inside of the tube, we found 12 females and 16 males. Morphological redescription of the species is especially urgent due to the publication of Schön et al. (2017) reporting of at least three different C. golyschkinae and one C. cf. golyschkinae dwelling in Baikal. Geographic distribution. Endemic to Lake Baikal, found in all three basins and in the Maloye More Strait at depths from 5 to 50 m (for details see Mazepova 1990: p. 318). Inhabits different substrates, but more often on stones with sponges and algae.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFB0F10A998EFF0E5D5FFE70.taxon	description	Figs. 19 – 21; 22 B, 22 E; 38 G; 39 F; 40 B, 40 H.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFB0F10A998EFF0E5D5FFE70.taxon	materials_examined	Type locality. Lake Baikal, one of two locations: 1) shallow water near Bolshoy Ushkaniy Island (approximate coordinates 53 º 51 ’ 06.48 ” N, 108 º 40 ’ 01.35 ” E); 2) shallow water near Kocherikovsky Cape (approximate coordinates 53 º 44 ’ 41.85 ” N, 107 º 52 ’ 27.82 ” E). Type material. Lectotype No. O 13 (female) and paralectotype No. 1 (male): dwm No. O 5 - 180872. Paralectotypes Nos. 2 – 14 (13 females): dwm No. O 6 - 180872. Paralectotype No. 15 (male): dwm No. O 7 - 180872. Paralectotype No. 16 (male): dwm No. O 7 - 180872 (valves) and wm No. O 8 - 180872 (limbs). Paralectotype No. 17 (male): dwm No. O 7 - 180872 (valves) and wm No. O 9 - 180872 (limbs). Paralectotypes Nos. 18 – 26 (4 females; 5 males): swm No. 18. Paralectotype No. 27 (female): swm No. 18 (valves) and wm No. O 10 - 180872 (limbs). All ostracods were collected from two locations: 1) shallow water of Bolshoy Ushkaniy Island, August 18, 1972, depth 20 m, sand and stones with sponges, sample No. 395 from the collection of taxocoenoses of G. F. Mazepova; 2) near Kocherikovsky Cape, August 8, 1973, depth 5 m, sample No. 482 from the collection of taxocoenoses of G. F. Mazepova. Since all specimens were in one tube with a common label, we did not determine where each specimen was collected from.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFB0F10A998EFF0E5D5FFE70.taxon	description	Description. Female. Carapace (Figs. 19 A – 19 D; 20 A – 20 F; 39 F) laterally irregularly trapezoidal: L = 990 – 1040 µm (mean 1030 µm, n = 10), largest H = 650 – 675 µm (mean 665 µm, n = 10), situated slightly behind posterior border of anterior 1 / 4 L. Dorsal margins of valves slightly arched at center. Anterior end of carapace broadly rounded, posterior end narrowly rounded, almost straight. Ventral margins of both valves equally concave on inner side; ventral margin of RV concave on outer side as on inner side, and straight on LV. LV overlaps RV throughout except for dorsal margin. Both valves in center of ventral margin with weakly visible protrusions (resembling similar ones in Cytherissa burchani Mazepova, 1990); very small posterior-ventral protrusion on RV. Margins of protrusions smoothly passing to margin of valves. Inner lamella broad. Marginal pore canals long, occupying 80 – 100 % of width of inner lamella and ending in sensilla. Inner lamella of each valve with 34 – 35 marginal pore canals. Pore canals of outer lamella sieve-type, branching, grouped (up to five canals in group), single near margin of valves; each canal with one sensillum. Outer lamella of each valve with at least 95 – 115 pore canals. Inner side of each valve with about 40 – 45 canal apertures. Hinge teeth on RV, crenulated, not extending beyond valve margin; bar on LV, slightly crenulated. Microrelief of valves surface homogeneous, consisting of small circular pits; diameter and depth of pits slightly decreasing at margins of valves (Fig. 22 B). Site of greatest width of carapace on ventral and dorsal views weakly pronounced and located at site of central 1 / 3 L (Fig. 20 C, 20 D). A 1, A 2, Md, Mxl, L 5 – L 7 as in C. heckyi, but distal segments of L 5 – L 7 partially fused. Male. Carapace (Figs. 19 E – 19 H; 21 A – 21 F; 39 F) slightly longer and lower than in female: L = 1065 – 1120 µm (mean 1090 µm, n = 6), H = 650 – 675 µm (mean 660 µm, n = 6). In dorsal and ventral views, males (Fig. 21 C, 21 D) narrower than females (Fig. 20 C, 20 D). Site of greatest width less pronounced. Posteroventral protrusion of RV larger than in female; ventral-medial protrusions very weakly pronounced and shifted closer to center of valves. Geniculate (transformed) legs on right side of body. Other morphological features of carapace structure, microrelief, A 1, A 2, Md, Mxl, left (non-geniculate) legs L 5 and L 6 as in female. Both legs of L 7 and right (geniculate) L 5 as in male C. heckyi, but distal segments of non-geniculate L 5 (Fig. 40 B), L 6 and both L 7 partially fused. L 6. Right leg. Protopod with four setae and several groups of pseudochaetae. Endopod one-segmented (Fig. 40 H), with one seta in center of segment and distal gently pointed outgrowth. Hemipenis (Figs 22 E; 38 G) large, elongate-triangular; outer appendage triangular, with spatulate widened tip. Length of hemipenis in quiescent state 515 µm (n = 1), greatest width 340 µm. Diameter of copulatory process 180 – 215 µm. Brush organ. Both rami with 12 apical setae, row of small pseudochaetae in medial part and row of pseudochaetae in subapical part; row of apical pseudochaetae either very small or absent.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFB0F10A998EFF0E5D5FFE70.taxon	diagnosis	Differential diagnosis. The shells of C. obrutshevi individuals are morphologically similar to the specimens of Cytherissa florensovi Mazepova, 1990 and C. golyschkinae. The species differ by the valve outlines laterally and carapace shape in dorsal and ventral views. G. F. Mazepova (1990: pp. 312) mentioned that C. obrutshevi and C. florensovi were considered in common for a long time. Notes. The list of type specimens (Mazepova 2001: pp. 542) includes 30 paratypes (20 females and 10 males). The handwritten version of G. F. Mazepova lists 39 type specimens (26 females and 13 males). The tube label shows 30 type specimens (20 females and 10 males). Paratype designation is not valid without a holotype, thus, all individuals are syntypes (ICZN, 1999). Inside of the tube, we saw and examined only 28 type specimens (19 females and 9 males). We failed to find the 11 remaining syntypes (in accordance with a handwritten catalog of type specimens) or two syntypes (according to the label and published list of type specimens) that were most likely lost. Geographic distribution. Endemic to Lake Baikal. Reliable distribution is unknown, as the species was counted together with C. florensovi Mazepova, 1990. Found in all basins of the lake at depths of 5 – 50 m (for details see Mazepova 1990: p. 312). Inhabits on sand and stones.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFB4F139998EF9A65DDCFF08.taxon	description	Figs. 23 – 26; 38 H; 39 G; 40 L.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFB4F139998EF9A65DDCFF08.taxon	materials_examined	Type locality. Lake Baikal, middle basin, underwater Academichesky Ridge (approximate coordinates 53 º 37 ’ 10.42 ” N, 108 º 10 ’ 11.69 ” E). Type material. Lectotype No. O 14 (female): dwm No. O 1 - 060872. Paralectotypes Nos. 1 – 6 (6 females): dwm No. O 2 - 060872. Paralectotypes Nos. 7, 8 (2 males): dwm No. O 3 - 060872. Paralectotypes Nos. 9 – 18 (7 females; 3 males): swm No. 34. Paralectotypes Nos. 19 (male): swm No. 34 (valves) and wm No. O 4 - 060872 (limbs). Paralectotype No. 20 (male): swm No. 34 (valves) and wm No. O 5 - 060872 (limbs). Paralectotype No. 21 (male): wm No. O 6 - 060872 (limbs). Paralectotype No. 22 (female): swm No. 34 (valves) and wm No. O 7 - 060872 (limbs). All ostracods were collected in the middle basin of Lake Baikal, underwater Academichesky Ridge, August 6, 1972, depth 230 m, sample No. 337 from the collection of taxocoenoses of G. F. Mazepova.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFB4F139998EF9A65DDCFF08.taxon	description	Description. Female. Carapace (Figs. 23 A – 23 D; 24 A – 24 F; 39 G) laterally rectangular-ovate: L = 780 – 830 µm (mean 800 µm, n = 7), largest H = 495 – 520 µm (mean 515 µm, n = 7), located at posterior border of anterior 1 / 3 of L. Dorsal margins of valves slightly arcuate. Anterior end of carapace broadly rounded, posterior end almost straight, narrowly rounded. Ventral margins of both valves equally concave on inner side, and almost straight, slightly concave on outer side. LV slightly overlaps RV throughout. Inner lamella very broad. Marginal pore canals long, occupying 65 – 100 % of width of inner lamella and ending in sensilla. Inner lamella of each valve with 25 – 27 marginal pore canals. Pore canals of outer lamella sieve-type, branching, grouped (up to four canals in a group), single near margin of valves; each canal with one sensillum. Outer lamella of each valve with at least 125 – 130 pore canals. Inner side of each valve with about 30 – 32 canal apertures. Hinge teeth on RV, slightly crenulated, not extending beyond valve margin; bar on LV, slightly crenulated. Microrelief of valves surface heterogeneous. Most of valves smooth, but in center small depressions corresponding to adductor muscle scars (located on inner side) (Fig. 26 A). Posterior part of dorsal and ventral margins of valves with long ridges (ventral one longer) covered with pitted microrelief (Fig. 26 B, 26 C). Microrelief appears deeper and more evenly spaced on dorsal side, while on ventral side less deep but more frequent. Site of greatest carapace width on ventral and dorsal views at central part of L (Fig. 24 C, 24 D). A 1, A 2, Md, Mxl, L 5 – L 7 as in C. heckyi, but distal segments of L 5 partially fused. Male. Carapace (Figs. 23 E – 23 H; 25 A – 25 E; 39 G) slightly longer than in female: L = 805 – 830 µm (mean 820 µm, n = 6), H = 495 – 520 µm (mean 515 µm, n = 6). Site of greatest width on dorsal (Fig. 25 C) and ventral views expressed much weaker than in female (Fig. 24 C, 24 D). Geniculate (transformed) legs on right side of body. Other morphological features of carapace structure, microrelief, A 1, A 2, Md, Mxl, left (non-geniculate) legs L 5 and L 6 as in female; distal segments of L 5 partially fused. Both legs of L 7 and right (geniculate) L 5 as in male C. heckyi. L 6. Right leg. Protopod with four setae and one group of pseudochaetae. Endopod two-segmented (Fig. 40 L), first segment with small seta. Distal part of second segment with gently pointed outgrowth. Hemipenis (Figs 26 D; 38 H) small, elongate-triangular; outer appendage lanceolate. Length of hemipenis in quiescent state 365 µm (n = 1), greatest width 235 µm. Diameter of copulatory process 115 – 135 µm. Brush organ. Both rami with 14 apical setae, rows of small pseudochaetae in medial, subapical and apical parts.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFB4F139998EF9A65DDCFF08.taxon	diagnosis	Differential diagnosis. The carapace outlines of C. calva are vaguely similar to the individuals of C. dextima. The species are discriminated by dinstict shell microrelief: the valves of C. calva are to a larger extent smooth with pits on the posterior part of the dorsal and ventral margins, whereas the microrelief in C. dextima is almost homogenous and consists of large cells. Notes. The type specimen list (Mazepova 2001 pp. 552) of C. calva shows 24 paratypes (15 females and 9 males), which is consistent with the handwritten version and the tube label. Paratype designation is not valid without a holotype, therefore, all individuals are referred to as syntypes. We found and examined only 23 syntypes (15 females and 8 males). The location of the remaining syntype is unknown, and probably it is lost. Geographic distribution. Endemic to Lake Baikal, found in the northern and middle basins at depths from 10 to 20 m (for details see Mazepova 1990: p. 389) and on the underwater Academichesky Ridge (depth unknown). Inhabits various substrates, including silt with sand.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFB4F139998EF9A65DDCFF08.taxon	materials_examined	Type locality. Lake Baikal, Maloye More Strait, one of two locations: 1) near Ulan-Baysan Cape (second name Zantyk Cape) (approximate coordinates 53 º 19 ’ 24.92 ” N, 107 º 38 ’ 45.39 ” E); 2) near the Kharansa Island (approximate coordinates 53 º 14 ’ 17.09 ” N, 107 º 24 ’ 42.42 ” E). Type material. Lectotype No. O 15 (female) and paralectotype No. 1: dwm No. O 32 - 130868. Paralectotypes Nos. 2 – 14 (13 females): dwm No. O 33 - 130868. Paralectotypes Nos. 15 – 20 (6 males): dwm No. O 34 - 130868. Paralectotypes Nos. 21 – 28, 32 (5 females; 4 males): swm No. 32. Paralectotype No. 29 (male): swm No. 32 (valves) and wm No. O 35 - 130868 (limbs). Paralectotype No. 30 (male): swm No. 32 (valves) and wm No. O 36 - 130868 (limbs). Paralectotype No. 31 (female): swm No. 32 (valves) and wm No. O 37 - 130868 (limbs). All ostracods were collected in the Maloye More Strait, in one of two locations: 1) near Ulan-Baysan Cape (second name Zantyk Cape), August 13, 1968, depth 25 m, sand with chara algae, sample No. 175 from the collection of taxocoenoses of G. F. Mazepova; 2) near Kharansa Island, August 16, 1968, depth 25 m, sand with detritus, sample No. 182 from the collection of taxocoenoses of G. F. Mazepova. Since all specimens were in one tube with a common label, we did not determine where each specimen was collected from.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFB4F139998EF9A65DDCFF08.taxon	description	Description. Female. Carapace (Figs. 27 A – 27 D; 28 A – 28 G; 39 H) laterally elongate-ovate: L = 730 – 780 µm (mean 760 µm, n = 10), largest H = 470 – 495 µm (mean 485 µm, n = 10), located on posterior border of anterior 1 / 3 L. Dorsal margins of valves slightly arched at center. Anterior end of carapace broadly rounded, posterior end almost straight, narrowly rounded. Ventral margins of both valves equally concave on inner side and straight with small protrusions on outer side. LV overlaps RV throughout except for the center of dorsal margin. Inner lamella broad. Marginal pore canals may be short and not reach margin of inner lamella or occupy 100 % of width of inner lamella; some marginal pore canals branching, especially in anterior part of valves. Inner lamella of each valve with 30 – 31 marginal pore canals (8 – 9 short, 22 long). Pore canals of outer lamella sieve-type, branching, grouped (up to six canals in a group), single near margin of valves; each canal with one sensillum. Outer lamella of each valve with at least 230 – 245 pore canals. Inner side of each valve with approximately 45 canal apertures. Hinge teeth on RV, distinctly crenulated, posterior tooth slightly extending beyond margin of valve; bar on LV, crenulated. Microrelief of valves surface heterogeneous, consisting of pits of different diameter and depth. In central part of valves (Fig. 33 A), diameter and depth of pits significantly larger than in anterior (Fig. 33 B) and posterior parts. Site of greatest carapace width in ventral and dorsal views is at posterior border of 2 / 3 L (Fig. 28 C, 28 D). A 1, A 2, Md, Mxl, L 5 – L 7 (Fig. 28 E) as in C. heckyi, but distal segments of L 5 partially fused. Male. Carapace (Figs. 27 E – 27 H; 29 A – 29 F; 39 H) slightly longer and lower than in female: L = 805 – 860 µm (mean 830 µm, n = 10), H = 450 – 480 µm (mean 470 µm, n = 10). On dorsal and ventral views, site of greatest width pronounced much more weakly (Fig. 29 C, 29 D) than in female (Fig. 28 C, 28 D). Geniculate (transformed) legs on right side of body. Other morphological features of carapace structure, microrelief, A 1, A 2, Md, Mxl, left (non-geniculate) legs L 5 and L 6 as in female; distal segments of L 5 (Fig. 40 E) partially fused. Both legs of L 7 and right (geniculate) L 5 as in male C. heckyi. L 6. Right leg. Protopod with four setae and several groups of pseudochaetae. Endopod two-segmented (Fig. 40 N). First segment with small seta. Distal part of second segment with gently pointed outgrowth. Hemipenis (Fig. 38 D) small, triangular; outer appendage triangular. Length of hemipenis in quiescent state 315 µm (n = 1), greatest width 255 µm. Diameter of copulatory process 70 – 90 µm. Brush organ. Both rami with 12 apical setae, rows of small pseudochaetae in medial, subapical and apical parts.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFB4F139998EF9A65DDCFF08.taxon	diagnosis	Differential diagnosis. The broadly oval outline of C. plena valves, dorsally and ventrally, remotely resembles Cytherissa sernovi ovata Bronstein, 1947, yet they differ in the valve shape laterally. Notes. The list of type specimens (Mazepova 2001: pp. 543) includes 29 paratypes (21 females and 8 males), that as a whole coincides with the handwritten catalog and the label inside the tube. However, the handwritten version locates sampling site of 29 individuals opposite Ulan-Baysan Cape, but there is no indication of the number of specimens found near Kharansa Island. For the most part, G. F. Mazepova indicated the number of type specimens collected for the type series at each of the sampling sites except for this case. The tube contained 32 individuals (3 more than indicated in all sources). We assume that 29 specimens were collected opposite Ulan-Baysan Cape, and 3 at Kharansa Island. Paratype designation is not valid without a holotype, hence, all the individuals are syntypes (ICZN 1999). Geographic distribution. Endemic to Lake Baikal, found in the northern basin and in the Maloye More Strait at depths from 10 to 28 m (for details see Mazepova 1990: p. 325). Inhabits on sand.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFB4F139998EF9A65DDCFF08.taxon	materials_examined	Type locality. Lake Baikal, Angara River source, Listvennichny Bay, Listvyanka Settlement, opposite the Baikal Museum of the Siberian Branch of the Russian Academy of Sciences (approximate coordinates 51 º 52 ’ 03.76 ” N, 104 º 49 ’ 50.57 ” E). Type material. Lectotype No. O 16 (female) and paralectotype No. 1 (male): dwm No. O 1 - 260368. Paralectotypes Nos. 2 – 5 (4 females): dwm No. O 2 - 260368. Paralectotypes Nos. 6, 7 (2 males): dwm No. O 3 - 260368. Paralectotypes Nos. 8 – 15 (4 females; 4 males): swm No. 27. Paralectotype No. 16 (female): swm No. 27 (valves) and wm No. O 4 - 260368 (limbs). Paralectotype No. 17 (male): swm No. 27 (valves) and wm No. O 5 - 260368 (limbs). Paralectotype No. 18 (male): swm No. 27 (valves) and wm No. O 6 - 260368 (limbs). All specimens were collected near the source of the Angara River, Listvennichny Bay, opposite the building of the Baikal Museum (Listvyanka Settlement), on March 26, 1968. The specimens are from two samples: 1) 4.5 – 5 m depth, gravel and sand, sample No. 109 from the collection of taxocoenoses of G. F. Mazepova; 2) 12 m depth, stone with sponges and gravel, sample No. 111 from the collection of taxocoenoses of G. F. Mazepova. Since all specimens were in one tube with a common label, we did not determine where each specimen was collected from.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFB4F139998EF9A65DDCFF08.taxon	description	Description. Female. Carapace (Figs. 30 A – 30 D; 31 A – 31 F; 39 I) laterally rectangular-trapezoidal: L = 960 – 1015 µm (mean 980 µm, n = 7), largest H = 600 – 625 µm (mean 615 µm, n = 7), located on posterior border of anterior 1 / 4 L. Dorsal margins of valves slightly arched at center. Anterior end of carapace broadly rounded, posterior end almost straight, narrowly rounded. Ventral margins of both valves on inner and outer sides almost equally concave. LV overlaps RV throughout except for dorsal and posterior margins. Small posterior-ventral protrusion on RV (much larger in male). Inner lamella narrow. Marginal pore canals occupying 60 – 100 % of width of inner lamella and ending in sensilla. Inner lamella of each valve with 21 – 22 marginal pore canals. Pore canals of outer lamella sieve-type, branching, grouped (up to five canals in a group), single near margin of valves; each canal with one sensillum. Outer lamella of each valve with at least 140 – 160 pore canals. Inner side of each valve with about 45 – 48 canal apertures. Hinge teeth on RV, weakly crenulated, posterior tooth slightly extending beyond margin of valves; bar on LV, slightly crenulated. Microrelief of the valve surface elatively homogeneous and complex, consisting of large cells of different shapes with smaller cells of rounded shape (Fig. 33 C, 33 D). Site of greatest carapace width on ventral and dorsal views at posterior border of 2 / 3 L (Fig. 31 C, 31 D). A 1, A 2, Md, Mxl, L 5 – L 7 as in C. heckyi, but distal segments of L 5 partially fused. Male. Carapace (Figs. 30 E – 30 H; 32 A – 32 F; 39 I) slightly longer and lower than in female: L = 960 – 1015 µm (mean 990 µm, n = 10), H = 545 – 570 µm (mean 565 µm, n = 7). In dorsal and ventral views, site of greatest width much less pronounced (Fig. 32 C, 32 D) than in female (Fig. 31 C, 31 D) and shifted to posterior 4 / 5 L. The posterior-ventral protrusion more pronounced than in female. Geniculate (transformed) legs on right side of body. Other morphological features of carapace structure, microrelief, A 1, A 2, Md, Mxl, left (non-geniculate) legs L 5 and L 6 as in female; distal segments of L 5 partially fused. Both legs of L 7 and right (geniculate) L 5 as in male C. heckyi. L 6. Right leg. Protopod with four setae and several groups of pseudochaetae. Endopod two-segmented (Fig. 40 M). First segment with small seta. Second segment with distal pointed outgrowth. Hemipenis (Fig. 38 I) medium-sized, elongate-triangular; outer appendage long, elongate-lanceolate. Length of hemipenis in quiescent state 475 µm (n = 1), greatest width 325 µm. Diameter of copulatory process 140 µm. Brush organ (Fig. 40 R). Both rami with 15 apical setae, rows of small pseudochaetae in medial, subapical and apical parts.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FFB4F139998EF9A65DDCFF08.taxon	diagnosis	Differential diagnosis. The outlines of C. bisetosa carapace and valves are similar to many Baikalian species of this genus, however, the surface microrelief is unique. According to G. F. Mazepova’s monograph (1990: pp. 411), only this species has a complex microrelief composed of large cells of irregular shape, inside of which we find smaller cells. Examination of G. F. Mazepova’s collection of taxocoenoses revealed at least two more Cytherissa spp. species with analogous type of microrelief, but with markedly distinct valve outlines in contrast to C. bisetosa. Notes. The list of type specimens (Mazepova 2001: pp. 553, 554) includes 21 paratypes (10 females and 11 males) that corresponds to the handwritten catalog of type specimens and the label in the tube. Inside of the tube we found and examined only 19 type specimens (10 females and 9 males). The location of two more syntypes is unknown, they are most likely lost. Geographic distribution. Endemic to Lake Baikal, found in the southern basin at depths from 3.5 to 5 m (for details see Mazepova 1990: p. 399). Inhabits on stones with sponges.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FF83F122998EFA4A5BCCF8BB.taxon	description	Figs. 34 – 37; 38 J; 39 J; 40 D, 40 O.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FF83F122998EFA4A5BCCF8BB.taxon	materials_examined	Type locality. According to the label, specimens were collected from three different locations of Lake Baikal: 1) the underwater Academichesky Ridge (approximate coordinates 53 º 37 ’ 10.42 ” N, 108 º 10 ’ 11.69 ” E); 2) southern basin, near Bugul’deika Village (approximate coordinates 52 º 30 ’ 47.88 ” N, 106 º 04 ’ 03.66 ” E); 3) between Eligey and Gorevoi Utes Cape (approximate coordinates 53 º 22 ’ 56.97 ” N, 108 º 21 ’ 44.49 ’’ E). Type material. Lectotype No. O 17 (female) and paralectotype No. 1 (male): dwm No. O 16 - 060872. Paralectotypes Nos. 2 – 9 (8 females): dwm No. O 17 - 060872. Paralectotypes Nos. 10 – 16 (7 males): dwm No. O 18 - 060872. Paralectotypes Nos. 17 – 24 (4 females; 4 males): swm No. 33. Paralectotype No. 25 (female): swm No. 33 (valves) and wm No. O 19 - 060872 (limbs). Paralectotype No. 26 (male): swm No. 33 (valves) and wm No. O 20 - 060872 (limbs). Paralectotype No. 27 (male): swm No. 33 (valves) and wm No. O 21 - 060872 (limbs). According to the label, specimens were collected in three different locations of Lake Baikal: 1) 11 females and 9 males: the underwater Academichesky Ridge, August 6, 1972, depth 230 m, sample No. 337 from the collection of taxocoenoses of G. F. Mazepova; 2) 14 females: southern basin, near Bugul’deika Village, September 13, 1991, 360 m depth, brown silt, sampled using a research deep-submergence vehicle “ Pisces ”; 3) 3 males: between Eligey River and Gorevoi Utes Cape, August 9, 1972, 520 m depth. Since all specimens were in one tube with a common label, we did not determine where each particular specimen was collected from.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FF83F122998EFA4A5BCCF8BB.taxon	description	Description. Female. Carapace (Figs. 34 A – 34 D; 35 A – 35 F; 39 J) laterally oval-ovate: L = 730 – 780 µm (mean 755 µm, n = 10), largest H = 495 – 520 µm (mean 510 µm, n = 10), located on posterior border of anterior 1 / 3 L. Dorsal margins of valves slightly arcuate at center. Anterior end of carapace broadly rounded, posterior end almost straight, narrowly rounded. Ventral margins of both valves equally concave on inner side and arcuate on outer side; ventral margin protrudes more strongly on RV than on LV. RV overlaps LV throughout. Inner lamella broad. Marginal pore canals may be short and not reach margin of inner lamella or occupy 100 % of width of inner lamella; some marginal pore canals branching (in anterior part of valves). Inner lamella of each valve with 26 – 33 marginal pore canals (8 – 12 short, 18 – 21 long). Pore canals of outer lamella sieve-type, branching, grouped (up to five canals in group), single near margin of valves; each canal with one sensillum (Fig. 37 B, 37 D, 37 E). Single pore canals near valve margin may be elongate (Fig. 37 D) or round (Fig. 37 E). Outer lamella of each valve with at least 125 – 155 pore canals. Inner side of each valve with approximately 40 canal apertures. Hinge teeth on LV, crenulated, posterior tooth slightly extending beyond margin of valve; bar on RV, almost smooth. Microrelief of valves surface almost homogeneous, consisting of large pits, diameter almost equal on entire surface of valves (Fig. 37 A). Dorsal margin almost smooth, with highly smoothed microrelief. Ventral margin with highly elongated pits; row of very small pits along valve margin (Fig. 37 C). Site of greatest carapace width on ventral and dorsal views in central part of L (Fig. 35 C, 35 D). A 1, A 2, Md, Mxl, L 5 – L 7 as in female C. heckyi. Male. Carapace (Figs. 34 E – 34 H; 36 A – 36 F; 39 J) slightly longer and taller than in female: L = 805 – 860 µm (mean 835 µm, n = 10), H = 495 – 520 µm (mean 515 µm, n = 10). In dorsal and ventral views, males (Fig. 36 C, 36 D) significantly narrower than females (Fig. 35 C, 35 D). Microrelief on dorsal margin more pronounced (Fig. 36 D) than in females (Fig. 35 D). Inner lamella of each valve with 29 – 31 marginal pore canals. Geniculate (transformed) legs on left side of body. Other morphological features of carapace structure, microrelief, A 1, A 2, Md, Mxl, right (non-geniculate) legs L 5 (Fig. 40 D) and L 6 as in female. Both legs L 7 and geniculate L 5 as in male C. heckyi. L 6. Left leg. Protopod with four setae and several groups of pseudochaetae. Endopod one-segmented (Fig. 40 O), most probably without seta (or very small), distal part with gently pointed outgrowth. Hemipenis (Fig. 38 J) small, elongate-triangular; outer appendage lanceolate, with slightly curved main axis. Length of hemipenis in quiescent state 370 µm (n = 1), greatest width 265 µm. Diameter of copulatory process 105 – 125 µm. Brush organ. Both rami with 25 apical setae, rows of small pseudochaetae in medial, subapical and apical parts.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FF83F122998EFA4A5BCCF8BB.taxon	diagnosis	Differential diagnosis. The hinge teeth on the left valve and cellular microrelief of the valves of C. sinistra are identical with the individuals of the recently redescribed Cytherissa latirecta Mazepova, 1985 (Alekseeva et al. 2025 c). The species have well-distinguished valve outlines (in lateral view) and carapace shape in dorsal and ventral views. The outlines of C. sinistra shells are generally similar to C. dextima individuals, but the first species has hinge teeth on the left valve and the second, on the right valve.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FF83F122998EFA4A5BCCF8BB.taxon	discussion	Notes. The list of type specimens (Mazepova 2001: pp. 551, 552) includes 20 paratypes (11 females and 9 males). The handwritten version of G. F. Mazepova’s catalog lists many more — 37 type specimens (25 females and 12 males); among them 11 females and 9 males were collected at the underwater Akademicheskiy Ridge, 14 females opposite Bugul’deyka Village and 3 males between Eligey River and Gorevoy Utes Cape. The label on the tube shows 27 types specimens (15 females and 12 males), indicating the same three sampling sites mentioned above. Paratype designation is not valid without a holotype, thus all the specimens are referred to as syntypes. Inside of the tube we found and analyzed 28 type specimens (14 females and 14 males).	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
03B5D979FF83F122998EFA4A5BCCF8BB.taxon	distribution	Geographic distribution. Endemic to Lake Baikal, found in the northern and southern basins, in the Maloye More Strait, at depths from 50 to 900 m (for details see Mazepova 1990: p. 386). Inhabits silty sand, silt and clay.	en	Alekseeva, Tatyana M., Krivorotkin, Roman S., Timoshkin, Oleg A. (2025): Redescriptions of ten endemic Cytherissa species (Ostracoda, Podocopida, Cytherideidae) from the coastal and deep-water zones of Lake Baikal. Zootaxa 5673 (3): 301-354, DOI: 10.11646/zootaxa.5673.3.1, URL: https://doi.org/10.11646/zootaxa.5673.3.1
