taxonID	type	description	language	source
B6204209FFD8FFC34499F8F7C82D5EE9.taxon	description	(Figs 1 – 6)	en	Savatenalinton, Sukonthip (2025): Two new species of freshwater ostracods (Crustacea: Ostracoda) from the northeast of Thailand, with notes on sexually reproducing populations of Chrissia and Strandesia. Zootaxa 5717 (2): 235-257, DOI: 10.11646/zootaxa.5717.2.4, URL: https://doi.org/10.11646/zootaxa.5717.2.4
B6204209FFD8FFC34499F8F7C82D5EE9.taxon	etymology	Etymology. The species is named after the King, Ue-Lue Nakarat, in the Naka legend of Bueng Khong Long District where the new species was discovered.	en	Savatenalinton, Sukonthip (2025): Two new species of freshwater ostracods (Crustacea: Ostracoda) from the northeast of Thailand, with notes on sexually reproducing populations of Chrissia and Strandesia. Zootaxa 5717 (2): 235-257, DOI: 10.11646/zootaxa.5717.2.4, URL: https://doi.org/10.11646/zootaxa.5717.2.4
B6204209FFD8FFC34499F8F7C82D5EE9.taxon	diagnosis	Diagnosis. Cp in lateral view elongated, length c. 1.77 mm in female (H / L = 0.40 – 0.42), c. 1.58 mm in male (H / L = 0.40 – 0.41), greatest H situated at mid-length, Cp in dorsal view elongated with narrow anterior and posterior extremities, RV overlapping LV along all free margins, anteriorly slightly larger than posteriorly, valve surface smooth with sparse rimmed-pore setae, both valves with marginal anterior selvage, rounded anterior margins, narrowly rounded posterior margins with blunt tip, and wide anterior inner lamella without inner list. A 1 with small, unsegmented RO. A 2 natatory setae long (reaching beyond tip of terminal claws), aesthetasc Y slender, three-segmented. Male A 2 with claw-like z 1 and z 2 setae, strongly reduced claw G 1 and with claw G 3 modified to thin setae, claw Gm large with robust teeth, claw GM considerably reduced to short and thin seta. Md-palp with short α-seta, third seta of lateral apical setae on penultimate segment short, terminal segment elongated with three claws and two setae. Mx 1 - palp with elongated terminal segment bearing two claws and three setae, two large bristles on 3 rd endite serrated. T 2 with short and thin d 1 and d 2 setae, h 2 claw with setules far from its tip. CR well-developed, asymmetrical with right CR larger (but slightly shorter) than left one, right ramus with c. eight groups of long and robust spines on ventral margin, left ramus with c. 6 groups of small spines and setules on ventral margin, claws Ga and Gp of both CR strongly serrated with two subsets of robust spines. CR attachment with basal triangular loop. Male T 1 palps asymmetrical, basal segment of right and left palps subquadrate, terminal segment of both palps elongated, left one narrower than that of right one. Hp with subrectangular ms, widely rounded distal margin, medially slightly concave with marginal tiny warts, ls subquadrate with widely rounded distal margin, distal inner corner bearing tiny warts and fine setules, dls with pointed protrusion; Hp internally with large bladder-like part ‘ c’ of labyrinth, postlabyrinthal spermiduct curved, with three loop. ZO elongated with c. 25 spiny whorls.	en	Savatenalinton, Sukonthip (2025): Two new species of freshwater ostracods (Crustacea: Ostracoda) from the northeast of Thailand, with notes on sexually reproducing populations of Chrissia and Strandesia. Zootaxa 5717 (2): 235-257, DOI: 10.11646/zootaxa.5717.2.4, URL: https://doi.org/10.11646/zootaxa.5717.2.4
B6204209FFD8FFC34499F8F7C82D5EE9.taxon	materials_examined	Type materials: Holotype. Female, soft parts of a dissected specimen preserved in glycerine on a slide, and valves stored dry in a micropalaeontological slide (MSU-ZOC. 426). Allotype. Male, stored like the holotype (MSU-ZOC. 427). Paratype. Male, stored like the holotype (MSU-ZOC. 428), whole individuals of three males and three females in 70 % ethanol (MSU-ZOC. 429). Type locality. A marshy area next to a weir connecting Bueng Khong Long (marsh) and a rice field, Bueng Khong Long District, Bueng Kan Province, Thailand (17 º 57.53 ′ N, 104 º 02.09 ′ E), coll. S. Savatenalinton, 18 Mar. 2024.	en	Savatenalinton, Sukonthip (2025): Two new species of freshwater ostracods (Crustacea: Ostracoda) from the northeast of Thailand, with notes on sexually reproducing populations of Chrissia and Strandesia. Zootaxa 5717 (2): 235-257, DOI: 10.11646/zootaxa.5717.2.4, URL: https://doi.org/10.11646/zootaxa.5717.2.4
B6204209FFD8FFC34499F8F7C82D5EE9.taxon	description	Measurements (in μm). Female: LV (n = 2), L = 1705 – 1726, H = 704 – 726; RV (n = 2), L = 1753 – 1774, H = 711 – 732. Male: LV (n = 2), L = 1558 – 1571, H = 619 – 641; RV (n = 2), L = 1551 – 1583, H = 621 – 643. Description of female. Cp in lateral view elongated (length c. 1.77 mm, H / L = 0.40 – 0.42), greatest height situated at mid-length, Cp in dorsal / ventral views elongated, greatest width situated at mid-length, narrower anterior and posterior extremities, RV overlapping LV along all free margins, anteriorly slightly larger than posteriorly, valve surface smooth with sparse rimmed-pore thin setae. LV in internal view (Figs 1 A, E – F) with rounded anterior margins, narrow posterior margin with blunt end, dorsal margin strongly arched, ventral margin slightly concave in front of mid-length, marginal selvage anteriorly, anterior calcified inner lamella wide without inner list, posterior calcified inner lamella narrow without inner list, one short ventral inner list situated at c. mid-length, marginal pore canals present. RV in internal view (Figs 1 B, G – H) with rounded anterior margins, narrow posterior margin with blunt end, dorsal margin strongly arched, ventral margin concave in front of mid-length, marginal selvage anteriorly, calcified inner lamella wide anteriorly, narrow posteriorly, without anterior and posterior inner lists, antero-dorsal and postero-dorsal parts with small, shallow pit-like structure, postero-dorsal one more elongated, marginal pore canals present. A 1 (Fig. 3 A) seven-segmented. First segment with one long dorso-subapical seta (reaching mid-length of next segment), two long ventro-apical setae, WO not seen. Second segment c. 1.3 times wider than long, with one short dorso-apical seta (length c. 1 / 4 of next segment) and small, unsegmented RO. Third segment bearing two setae: one long dorso-apical (reaching beyond tip of terminal segment) and one very short ventro-apical setae (not reaching mid-length of next segment). Fourth segment with two long dorsal setae and two short ventral setae, shortest one not reaching tip of next segment and with flagellum-like tip. Fifth segment dorsally with two long setae, ventrally with two setae (one long, one shorter), shorter one reaching beyond tip of terminal segment. Penultimate segment with four long apical setae and one very short seta (reaching mid-length of terminal segment). Terminal segment elongated (c. three times longer than width) with three apical setae (two long, one short) and remarkably long aesthetasc ya (length more than two times that of short seta). A 2 (Fig. 3 B) protopodite with two proximal setae and one long ventro-apical seta (reaching beyond tip of first endopodal segment), third proximal seta not seen. Exopodite with three (one long, two short) setae, long one reaching tip of first endopodal segment. Endopodite three-segmented. First endopodal segment with five long natatory setae (reaching beyond tips of terminal claws) and one short accompanying seta (reaching c. 1 / 3 of that of penultimate segment), aesthetasc Y medium size, three-segmented, situated at c. 1 / 3 of its segment length, ventro-apical seta long, reaching tip of terminal segment. Penultimate segment undivided, medially with two subequally short dorsal setae, four t-setae of unequal length, longest seta reaching beyond tip of claw Gm, distally with long z 1 – z 3 setae (z 1 shorter than other z setae, z 2 – z 3 not reaching tip of claws G 1), long aesthetasc y 2 (reaching slightly beyond tip of terminal segment), three large, serrated claws (G 1 – G 3), G 1 larger than other claws, G 2 shorter than other claws. Terminal segment with small ventro-apical projection set with fine marginal setules (not illustrated); distally with two claws (GM and Gm), medium length g seta (longer than claw Gm) and aesthetasc y 3, claw GM large, claw Gm remarkably short and thin (length c. half of that of GM), length of aesthetasc y 3 half of that of accompanying seta. Md-coxa (Fig. 3 D) elongated, distally set with rows of teeth (large dorsally and smaller ventrally) and small (smooth or hirsute) ventro-apical setae, and with one slightly hirsute dorso-subapical seta, the latter thin and short (not reaching base of teeth). Md-palp (Fig. 4 A) four-segmented. First segment composed of two large setae (S 1 and S 2) with long setules, one long and slender seta with few setules at its tip, and smooth, elongated α-seta with long thin tip. Second segment dorsally with three unequal long apical setae, shortest seta reaching tip of next segment; ventrally with group of three long, hirsute setae, one shorter hirsute seta (reaching tip of next segment) and cone-shaped, plumose β-seta with pointed tip. Penultimate segment bearing three groups of setae: dorsally with group of four unequal, long, subapical setae; laterally with short apical γ-seta (reaching beyond tip of terminal segment) and three (two long, one remarkably short and thin) apical setae, length of the longest seta more than two times of terminal segment length; ventrally with two subapical setae, one long (length c. two times of terminal segment), one very short (not reaching tip of its segment). Terminal segment elongated (length c. 1.6 times of width) bearing three claws and two thin setae, length of longest claws c. 2.8 times of that of terminal segment. Mx 1 (Figs 4 B – C) with two-segmented palp, basal segment of palp dorsally with group of four long, unequal apical setae, one of them with long setules; laterally with one subapical seta (reaching beyond tip of its segment), terminal segment cylindrical (length c. 1.6 times of width), apically with two claws and three setae (length of setae c. 3 / 4 of that of claws). Third endite basally with one long seta, apically with two large bristles bearing slightly serrated distal part. First endite with two unequally long sideways-directed bristles and two basal setae. T 1 (Figs 4 D – E): protopodite with two short a-setae, subequal in length, long b-and d-setae with long setules, c-seta absent; distally with 10 hirsute apical setae of unequal length and four (three long and one short) subapical setae with long setules. Endopodite very elongated, weakly built palp with three (one long with setules, two short) apical setae, length of long one c. 3.5 times of shortest one. T 2 (Fig. 5 A) five-segmented. Basal segment with short, thin d 1 and d 2 setae. Second segment with long, thin, hirsute e-seta (almost reaching tip of next segment). Penultimate segment divided, medially with medium length, slightly hirsute f-seta (reaching tip of terminal segment), distally with long apical g-seta (reaching c. 1 / 3 of h 2 claw). Terminal segment dorsally with one short apical h 1 seta, ventrally with one short subapical h 3 seta, h 1 and h 3 subequal in length, laterally with long, serrated apical h 2 claw (length c. 1.6 times of that of penultimate segment), setules on h 2 claw far from tip. T 3 (Fig. 5 B) three-segmented. First segment with long d 1, d 2 and dp setae, all hirsute and subequal in length. Second segment with medium-length apical e-seta (reaching mid-length of next segment). Third segment medially with short f-seta (not reaching tip of segment). Terminal segment with pincer organ and bearing very short h 1 seta, claw-like h 2 seta and long, hirsute h 3 seta. CR (Figs 5 C – D) well-developed, asymmetrical with right CR larger than left one, right ramus slightly shorter than left ramus. Right CR (Fig. 5 C) with c. eight groups of long and robust spines on ventral margin of ramus, spines in each group reduced in size towards posterior, claw Ga short (length c. 0.4 time of that of ramus), claw Gp short (length c. 2 / 3 of that of claw Ga), both claws strongly serrated with two subsets of large spines, sa seta thin and short (shorter than claw Gp), sp seta absent. Left CR (Fig. 5 D) with c. 6 groups of small spines and setules on ventral margin of ramus, claw Ga short (length c. 0.4 time of that of ramus), claw Gp short (length c. 2 / 3 of that of claw Ga), both claws strongly serrated with two subsets of large spines, sa seta thin and short (slightly longer than claw Gp), sp seta absent. CR attachment (Fig. 5 E) thin, basally with triangular loop and distally with two well-developed branches (db and vb). Description of male. Carapace and valves as in female, but somewhat smaller (length c. 1.58 mm, H / L = 0.40 – 0.41) (Figs 1 C – D, 2 A – D). All limbs as in female, except for last two segments of A 2, T 1, CR and reproductive organs. Penultimate segment of A 2 (Fig. 3 C) with claw-like z 1 and z 2 setae, considerably reduced claw G 1 and with claw G 3 reduced to thin setae; terminal segment with claw Gm large with distal pectinate shape, claw GM considerably reduced, length of GM c. half of length of Gm (Fig. 3 C). T 1 - endopodites forming asymmetrical prehensile palps; basal segment of right (Fig. 6 C) and left palps (Fig. 6 D) subquardrate with two long subapical spines; terminal segment of both palps elongated, left one narrower than that of right one. sa seta of right and left CR shorter than that of female, robust spines on ventral margin of right ramus shorter than those of female, small spines and setules on ventral margin of left ramus stronger than those of female with longest spine at subapical part. Hp (Figs 6 E – F) with ms subrectangular, widely rounded distal margin, medially concave with tiny warts on lateral margin, ls subquadrate with widely rounded distal margin, distal inner corner bearing tiny warts and fine setules, dls with pointed protrusion; Hp internally with large bladder-like part ‘ c’ of labyrinth, postlabyrinthal spermiduct curved, with three loops. ZO (Fig. 6 G) elongated with c. 25 spiny whorls.	en	Savatenalinton, Sukonthip (2025): Two new species of freshwater ostracods (Crustacea: Ostracoda) from the northeast of Thailand, with notes on sexually reproducing populations of Chrissia and Strandesia. Zootaxa 5717 (2): 235-257, DOI: 10.11646/zootaxa.5717.2.4, URL: https://doi.org/10.11646/zootaxa.5717.2.4
B6204209FFD8FFC34499F8F7C82D5EE9.taxon	distribution	Distribution. Northeast Thailand.	en	Savatenalinton, Sukonthip (2025): Two new species of freshwater ostracods (Crustacea: Ostracoda) from the northeast of Thailand, with notes on sexually reproducing populations of Chrissia and Strandesia. Zootaxa 5717 (2): 235-257, DOI: 10.11646/zootaxa.5717.2.4, URL: https://doi.org/10.11646/zootaxa.5717.2.4
B6204209FFD3FFDA4499FEE3C82D5EE9.taxon	description	(Figs 7 – 11)	en	Savatenalinton, Sukonthip (2025): Two new species of freshwater ostracods (Crustacea: Ostracoda) from the northeast of Thailand, with notes on sexually reproducing populations of Chrissia and Strandesia. Zootaxa 5717 (2): 235-257, DOI: 10.11646/zootaxa.5717.2.4, URL: https://doi.org/10.11646/zootaxa.5717.2.4
B6204209FFD3FFDA4499FEE3C82D5EE9.taxon	etymology	Etymology. The species is named after Bueng Kan Province, from which the new species was discovered.	en	Savatenalinton, Sukonthip (2025): Two new species of freshwater ostracods (Crustacea: Ostracoda) from the northeast of Thailand, with notes on sexually reproducing populations of Chrissia and Strandesia. Zootaxa 5717 (2): 235-257, DOI: 10.11646/zootaxa.5717.2.4, URL: https://doi.org/10.11646/zootaxa.5717.2.4
B6204209FFD3FFDA4499FEE3C82D5EE9.taxon	diagnosis	Diagnosis. Cp elongated in lateral view, length c. 760 μm in female (H / L = 0.56 – 0.57), c. 695 μm in male (H / L = 0.54 – 0.55), LV overlapping RV along all free margins, larger overlap anteriorly, Cp in dorsal view elongated with greatest W situated in front of mid-length, anterior and posterior margins of LV more protruded than RV; LV internally with groove along valve margin, incomplete inner list and marginal anterior selvage. A 1 seven-segmented with large and long RO, small WO, first segment without dorso-subapical seta, aesthetasc ya remarkably long (longer than shortest seta on terminal segment). A 2 with long natatory setae, aesthetasc Y large, three segmented, last segment larger than other segments, z 1 and z 3 setae intermediate length (not reaching tips of apical claws). Male A 2 with claw-like z 1 and z 2 setae and with claw G 2 and G 3 considerably reduced to thin and short setae, terminal segment with claw GM modified, carrying strong spines on distal half of claw, and with claw Gm strongly reduced to thin and short seta. β-seta on Md-palp large, cone-shaped with needle-like tip, terminal segment with three claws and two setae. Terminal segment of Mx 1 - palp elongated with three claws and two setae, two large bristles on third endite smooth. d-seta on T 1 present. T 2 with large d 1 and d 2 setae (length of d 1 seta c. 1.5 times of that of d 2 seta), f-seta markedly long. T 3 with short f-seta. CR slender, claw Ga less than half length of ramus, claw Gp c. 3 / 5 of that of claw Ga, sa seta shorter than claw Gp, sp seta thin with flagellum-like tip, reaching beyond tip of ramus. CR attachment with Triebel’s loop situated at middle of distal part of main branch. Hp with medial shield rounded, lateral shield elongated with blunt tip, postlabyrinthal spermiduct curved, with 2 loops. ZO with 17 spiny whorls, length about 3.4 times width.	en	Savatenalinton, Sukonthip (2025): Two new species of freshwater ostracods (Crustacea: Ostracoda) from the northeast of Thailand, with notes on sexually reproducing populations of Chrissia and Strandesia. Zootaxa 5717 (2): 235-257, DOI: 10.11646/zootaxa.5717.2.4, URL: https://doi.org/10.11646/zootaxa.5717.2.4
B6204209FFD3FFDA4499FEE3C82D5EE9.taxon	materials_examined	Type materials: Holotype. Female, soft parts of a dissected specimen preserved in glycerine on a slide, and valves stored dry in a micropalaeontological slide (MSU-ZOC. 430). Allotype. Male, stored like the holotype (MSU-ZOC. 431). Paratypes. Four females, stored like the holotype (MSU-ZOC. 432 to 435); three males, stored like the holotype (MSU-ZOC. 436 to 438), many whole individuals of females and males in 70 % ethanol (MSU-ZOC. 439). Type locality. A marshy area next to a weir connecting Bueng Khong Long (marsh) and a rice field, Bueng Khong Long District, Bueng Kan Province, Thailand (17 º 57.53 ′ N, 104 º 02.09 ′ E), coll. S. Savatenalinton, 18 Mar. 2024.	en	Savatenalinton, Sukonthip (2025): Two new species of freshwater ostracods (Crustacea: Ostracoda) from the northeast of Thailand, with notes on sexually reproducing populations of Chrissia and Strandesia. Zootaxa 5717 (2): 235-257, DOI: 10.11646/zootaxa.5717.2.4, URL: https://doi.org/10.11646/zootaxa.5717.2.4
B6204209FFD3FFDA4499FEE3C82D5EE9.taxon	description	Measurements (in μm). Female: Cp (n = 1), L = 764, W = 371; LV (n = 2), L = 739 – 764, H = 421 – 428; RV (n = 2), L = 732 – 742, H = 415 – 418. Male: Cp (n = 2), L = 682 – 704, H = 376, W = 311; LV (n = 1), L = 689, H = 374; RV (n = 1), L = 666, H = 363. Description of female. Cp elongated in lateral view (c. 760 μm, H / L = 0.56 – 0.57), anterior margin widely rounded, posterior margin narrowly rounded, LV overlapping RV along all free margins, larger overlap anteriorly, dorsal margin strongly arched, greatest height situated in front of mid-length, ventral margin somewhat straight, valve surface (Figs 7 A – C) with tiny tubercles and sparse thin rimmed-pore setae, tiny tubercles less prominent dorsally and ventrally. Cp in dorsal view (Fig. 7 D) elongated with greatest W situated in front of mid-length, anterior and posterior margins of LV more protruded than RV. LV in interior view (Figs 8 A – B, E – F) with groove along valve margin, marginal anterior selvage, anterior fused zone moderately wide, dorsal margin strongly arched, greatest height situated in front of mid-length, anterior margin widely rounded, posterior margin narrowly rounded with slightly pointed tip, postero-dorsal part angulated, ventral margin somewhat straight; calcified inner lamella relatively wide anteriorly, with incomplete inner list. RV in interior view (Figs 8 B, G – H) without marginal groove, with submarginal selvage, inner lamella without inner list, anteriorly broader than posteriorly, ventral margin somewhat straight. A 1 (Fig. 9 A) seven-segmented. First segment with two long ventro-apical setae, small WO, dorso-subapical seta absent. Second segment slightly wider than long, with one short dorso-apical seta (not reaching mid-length of next segment) and large and long RO. Third segment bearing one long dorso-apical seta (reaching mid-length of fifth segment) and one long, slightly hirsute ventro-apical seta (almost reaching tip of next segment). Fourth segment with two long dorsal setae and two intermediate length ventral setae, shortest seta reaching mid-length of sixth segment. Fifth segment dorsally with two long setae, ventrally with two (one long, one shorter) setae, shorter one reaching mid-length of terminal segment. Penultimate segment with four long setae. Terminal segment with three (two long, one short) apical setae and aesthetasc ya, length of short one c. 2 / 3 of that of aesthetasc ya, aesthetasc ya remarkably long (c. 2.7 times of that of terminal segment). A 2 (Fig. 9 B) protopodite with two ventro-proximal setae (third proximal seta not seen) and one long ventrosubapical seta. Exopodite with three (one long, two short) setae, long one reaching tip of first endopodal segment. Endopodite three-segmented. First endopodal segment with five long natatory setae (reaching tip of terminal claws) distally bearing sparsely distributed thin setules, and one shorter accompanying seta (not reaching mid-length of penultimate segment), aesthetasc Y large, three segmented, last segment larger than other segments, ventro-apical seta long (reaching tip of terminal segment), slightly hirsute. Penultimate segment undivided, medially with two (one long, one shorter) dorsal setae (shorter one not reaching tip of segment) and four ventral setae of unequal length (t 1 – t 4); distally with three serrated claws G 1 – G 3 (subequal in length), aesthetasc y 2 short (not reaching tip of terminal segment), z 1 – z 3 setae intermediate length, z 1 seta shortest (reaching less than half-length of claw G 1), z 2 and z 3 setae not reaching tips of apical claws. Terminal segment with two serrated claws GM and Gm (length of Gm c. 4 / 5 of that of GM), aesthetasc y 3 (length of aesthetasc y 3 c. 1 / 3 of that of Gm and c. 2 / 3 of that of accompanying seta) and g-seta with same length as aesthetasc y 3. Md-coxa (Fig. 9 D) elongated, distally set with rows of teeth (large dorsally and smaller ventrally) and small setae, and with one slightly hirsute dorso-subapical seta, the latter thin and short (not reaching base of teeth). Md-palp (Fig. 10 A) four-segmented. First segment with two large S 1 and S 2 setae, one long, smooth seta and one long, smooth α-seta, the latter with wide proximal part. Second segment dorsally with three dorsal apical setae (one long, one medium length and one short), length of the shortest seta c. 1 / 3 of that of the longest seta; ventrally with a group of three long hirsute setae, one shorter hirsute seta and the β-seta, the latter large, plumose, cone-shaped and with needle-like tip. Penultimate segment dorsally with a group of four unequal, long, subapical setae; laterally with an apical γ-seta and three further apical setae, the former stout, hirsute, long (length c. 2.6 times of that of terminal segment); ventrally with two (one long, one short) apical setae, short one reaching half way of terminal segment. Terminal segment bearing three claws and two setae. Mx 1 (Fig. 10 B) with two-segmented palp, three endites and large branchial plate; basal segment of palp with group of four long, unequal apical setae, one long subapical setae and laterally one short subapical seta (not reaching tip of terminal segment), terminal segment elongated with three claws and two setae. Two large bristles on third endite smooth. First endite with two unequally long sideways-directed bristles and two basal setae. T 1 (Fig. 10 C) protopodite with two short a-setae, long, hirsute b and d-setae, distally with 14 (10 apical, four subapical) hirsute setae of unequal length. Endopodite (not illustrated) weakly built palp with three unequal apical setae. T 2 (Fig. 10 D) five-segmented. Basal segment with large d 1 and d 2 setae, both hirsute, length of d 1 seta c. 1.5 times of that of d 2 seta. Second segment with short, hirsute e-seta (reaching mid-length of penultimate segment). Penultimate segment divided, proximal segment bearing markedly long, hirsute f-seta (reaching far beyond tip of terminal segment), distal segment with long g-seta (reaching beyond tip of terminal segment) and tiny spine-like seta. Terminal segment dorsally with long apical h 1, ventrally with long h 3 seta, h 1 longer than h 3, laterally with serrated claw h 2, length of claw h 2 longer than that of penultimate segment. T 3 (Fig. 10 E) three-segmented. First segment with unequally long d 1, d 2, dp setae, d 2 and dp setae not reaching tip of next segment. Second segment bearing apical e-seta of intermediate length (reaching slightly beyond mid-length of next segment). Third segment medially with f-seta (not reaching tip of segment). Terminal segment with apical pincer and three setae (h 1 – h 3), h 1 seta short, h 2 seta claw-like, subapical h 3 seta long and reflexed, length of the latter c. 3 / 4 of that of third segment. CR (Fig. 11 A) slender, ventral margin of ramus with tiny setules. Claws Ga and Gp serrated, length of claw Ga less than half length of that of ramus, length of claw Gp c. 3 / 5 of that of claw Ga, sa seta shorter than claw Gp, sp seta thin with flagellum-like tip, reaching beyond tip of ramus. CR attachment (Fig. 11 B) stout with Triebel’s loop situated at middle of distal part of main branch, db and vb well-developed. Description of male. Cp and valves as in female, but somewhat smaller (c. 695 μm, H / L = 0.54 – 0.55) (Figs 7 E – F). All limbs as in female, except for last two segments of A 2, T 1 and reproductive organs. Penultimate segment of A 2 with claw-like z 1 and z 2 setae and with claws G 1 and G 3 considerably reduced to thin and short setae; terminal segment with claw Gm modified, carrying strong spines on distal half of claw, and with claw GM strongly reduced to thin and short seta (Fig. 9 C). T 1 - endopodites forming asymmetrical prehensile palps; right palp (Fig. 11 C) with elongated basal segment bearing two short apical spines and with triangular terminal segment; left palp (Fig. 11 D) with elongated basal segment bearing tiny apical spine and tubercle and with elongated, hook-like curved terminal segment. Hp (Fig. 11 E) with medial shield rounded, lateral shield elongated with blunt tip. Postlabyrinthal spermiduct curved, with two loops. ZO (Fig. 11 F) set with 17 spiny whorls, length about 3.4 times width, distal and proximal end plates forming crown of petal-like structures.	en	Savatenalinton, Sukonthip (2025): Two new species of freshwater ostracods (Crustacea: Ostracoda) from the northeast of Thailand, with notes on sexually reproducing populations of Chrissia and Strandesia. Zootaxa 5717 (2): 235-257, DOI: 10.11646/zootaxa.5717.2.4, URL: https://doi.org/10.11646/zootaxa.5717.2.4
B6204209FFD3FFDA4499FEE3C82D5EE9.taxon	distribution	Distribution. Northeast Thailand.	en	Savatenalinton, Sukonthip (2025): Two new species of freshwater ostracods (Crustacea: Ostracoda) from the northeast of Thailand, with notes on sexually reproducing populations of Chrissia and Strandesia. Zootaxa 5717 (2): 235-257, DOI: 10.11646/zootaxa.5717.2.4, URL: https://doi.org/10.11646/zootaxa.5717.2.4
B6204209FFC9FFD84499F8F7CB5A5CBA.taxon	description	There are three types of reproductive modes in non-marine ostracods: parthenogenesis, sexual reproduction and geographical parthenogenesis (Horne et al. 1998). The first type occupies a large fraction of ostracods, including most species of Chrissia, which reproduce by parthenogenetic mode, based on indirect evidence (no males have been encountered to date). The second type is indicated by the occurrence of both sexes in all populations of the species, whereas species with partial existence of sexual populations are defined to the third group. All nine Chrissia species with sexual populations belong to the second type (G. W. Müller 1898, 1908, 1914; Sars 1924; Rome 1965; George et al. 1993). In the Thai ostracod fauna, the third mode of reproduction has been found only in two species of the subfamily Cypricercinae, namely Tanycypris siamensis Savatenalinton & Martens, 2009 (see Savatenalinton & Martens 2009; Savatenalinton 2014) and Strandesia martensi (see Savatenalinton 2024 a) in which sexually reproducing populations inhabited the middle part of the Chi River Basin and the distal part of the Lower Songkhram River Basin, respectively. This suggests that the appearance of sexual populations in the third type could relate to the habitat environments as both parts are commonly flooded in the rainy season. Taxonomic characters of Chrissia were comprehensively provided by Savatenalinton (2023 b), all of them non-sexual related characters, whereas diagnostic features, including characters of male reproductive organs, were summarized in the diagnoses of Herpetocypridinae tribes and genera, including Chrissia, by Martens (2001). Based on this summary, the male reproductive organs of C. ueluenakarati sp. nov. are congruent to the diagnosis of Chrissia, for example the medial shield of the Hp without a hook-like process and the two additional internal loops of the spermiduct. The detailed comparisons revealed that there are two groups of Chrissia Hp. The first group possesses the dorsal subtriangular protrusion on the ls, which has been seen in six species, including the new species: C. acuminata, C. bispinosa (G. W. Müller, 1914), C. fascigera, C. hodgsoni (Sars, 1924), C. smaragdina (Sars, 1924) and C. ueluenakarati sp. nov. (see G. W. Müller 1914; Sars 1924). On the other hand, the second group indicated by the absence of such a protrusion is composed of four species, namely C. ametra (G. W. Müller, 1908), C. sinuata, C. achandii and C. goddeerisi (see G. W. Müller 1898, 1908; Sars 1924; George et al. 1993). It should be noted that both aspects of the Hp exist in both Afrotropic and Oriental lineages.	en	Savatenalinton, Sukonthip (2025): Two new species of freshwater ostracods (Crustacea: Ostracoda) from the northeast of Thailand, with notes on sexually reproducing populations of Chrissia and Strandesia. Zootaxa 5717 (2): 235-257, DOI: 10.11646/zootaxa.5717.2.4, URL: https://doi.org/10.11646/zootaxa.5717.2.4
B6204209FFCBFFD94499FA89C95F5FD6.taxon	description	Apart from their similarity of Cp shape, S. buengkanensis sp. nov. also lacks a subapical dorsal seta on the A 1 first segment, which makes it resemble S. kraepelini more. Thus far, the absence of this seta in Strandesia has been recognized only in three species, namely S. kraepelini (see Savatenalinton & Martens 2010), S. karanovicae (Savatenalinton 2024 a) and S. buengkanensis sp. nov. (present study). Strandesia kraepelini was described based on materials from Java (Indonesia) (G. W. Müller 1906) and subsequently reported from other Southeast Asian countries (Victor & Fernando 1981 b, Savatenalinton & Suttajit 2016), while S. karanovicae was recently discovered from Thailand (Savatenalinton 2024 a). Hence, in the genus Strandesia, the absence of this seta is so far restricted to the Southeast Asian lineage. At present, the number of Strandesia species recorded in Southeast Asia is 20 (Table 2). Most of them are endemic, which would suggest that these species originate from this area. In addition, three of them, including the new species, are sexual populations in which males and females are found. Within the group in which the subapical dorsal seta on the A 1 first segment is absent, sexually reproducing populations occur only in S. buengkanensis sp. nov. This allows the comparisons of the male reproductive organs between this group and other Cypricercinae members. The comparisons revealed that, in S. buengkanensis sp. nov., the number of ZO spiny whorls is close to that of Pseudostrandesia (see Savatenalinton 2021; Smith et al. 2021). Additionally, like in Pseudostrandesia, the Hp morphology of the new Strandesia species belongs to type C according to the Hp model proposed by Savatenalinton & Martens (2009 b) and additional data by Savatenalinton (2021) and Smith et al. (2021). This could suggest that Strandesia without the subapical dorsal seta on the A 1 first segment form a group that is closer to Pseudostrandesia than other Strandesia, on the basis of the similarity of the male reproductive organs. This species group is also restricted to Southeast Asia, which is the proposed origin of Pseudostrandesia (Savatenalinton 2021; Smith et al. 2021).	en	Savatenalinton, Sukonthip (2025): Two new species of freshwater ostracods (Crustacea: Ostracoda) from the northeast of Thailand, with notes on sexually reproducing populations of Chrissia and Strandesia. Zootaxa 5717 (2): 235-257, DOI: 10.11646/zootaxa.5717.2.4, URL: https://doi.org/10.11646/zootaxa.5717.2.4
