Dolerocypris rossettii Savatenalinton, 2026, sp. nov.

Dolerocypris rossettii sp. nov. Figs 1, 2, 3, 4, 5 Type locality. THAILAND, Roi Et Province, Thawat Buri District, Kut Khaen (reservoir); 16.0023°N, 103.8013°E; 23 Oct. 2024; S. Savatenalinton leg. Other locality: THAILAND, Roi Et Province, Selaphum District, Nong Kae (swamp); 16.0481°N, 103.9985°E; 23 Oct. 2024; S. Savatenalinton leg. Material examined. Holotype: • ♀ (MSU -ZOC.519), dissected soft parts preserved in glycerin on a slide, Cp stored dry in a micropalaeontological cavity slide. Paratypes: • 3 ♀ (MSU -ZOC.520 to 522), dissected soft parts preserved in glycerin on slides, valves / Cp stored dry in micropalaeontological cavity slides. Deviation of name. The species is named after Prof. Giampaolo Rossetti (University of Parma, Italy), a prominent Italian ostracodologist, in recognition of his outstanding work on ostracod taxonomy and ecology and our long friendship. Dimensions (in μm). Cp (N = 2), L = 1405–1452, H = 456–460, W = 365–369; LV (N = 1), L = 1405, H = 472; RV (N = 1), L = 1421, H = 460. Diagnosis. Cp in lateral view elongated, RV overlapping LV anteriorly, LV overlapping RV posteriorly, valve surface with rimmed pore setae and striations observable under high magnification of SEM, LV with inwardly displaced selvage anteriorly and posteriorly, RV with inwardly displaced selvage anteriorly and submarginal selvage posteriorly, WO present, A 2 natatory setae long (reaching tip of terminal claws), aesthetasc Y four-segmented, Md palp bearing smooth, subtriangular α seta with long needle-like tip, short, broad and plumose β seta, and stout, plumose, subtriangular γ seta with long needle-like tip, terminal segment of Mx 1 - palp subquadrate, two large bristles on third endite smooth, T 1 with a, b and d setae, T 2 with short d 1 and d 2 setae, e seta short, CR claws long, large, set with strong denticles, length of Ga more than half of that of ramus, Gp reaching mid-length of Ga, Sa short (not reaching mid-length of Gp), Sp short (reaching slightly beyond tip of ramus). Description of female. Cp in lateral view (Fig. 1 A, C) elongated (length ca 3.2 times of height), anterior margin rounded, posterior margin narrower and rounded, RV overlapping LV anteriorly, LV overlapping RV posteriorly and ventrally, dorsal margin arched, greatest height situated at mid-length, valve surface with rimmed pore setae and striations observable under high magnification of SEM (Fig. 1 B), Cp pale whitish, medially with green patch. Cp in dorsal view (Fig. 1 D – F) elongated, with greatest width situated at mid-length. RV in interior view (Fig. 2 A – D) with prominent inwardly displaced selvage anteriorly, posterior selvage submarginal, calcified inner lamella wide and reticulated anteriorly and posteriorly, ventral margin slightly sinuate. Muscle scars consisting of six adductor scars (four small scars with two larger scars above) and two mandibular scars (Fig. 2 B). LV in interior view (Fig. 2 E – H) with prominent inwardly displaced selvage anteriorly and posteriorly, large marginal zone anteriorly, ventrally, and posteriorly, calcified inner lamella wide and reticulated anteriorly and posteriorly, and marginal groove along ventral margin. A 1 (Fig. 3 A): first segment with small proximal WO, one long dorso-subapical seta (reaching mid-length of next segment) and two subequally long ventro-apical setae. Second segment slightly wider than long, with one long dorso-apical seta (reaching mid-length of the next segment) and short RO. Third segment bearing two setae: one long dorso-apical seta, (reaching beyond tip of terminal segment), and one short ventro-apical seta (not reaching mid-length of next segment). Fourth segment with two long dorsal setae and two short ventral setae (short one reaching mid-length of next segment, longer one reaching tip of next segment). Fifth segment dorsally with two long setae, ventrally with two (one long, one short) setae, short one reaching tip of next segment. Sixth segment with four long apical setae and one short dorso-subapical seta. Terminal segment with aesthetasc y a and three (two long, one short) apical setae, length of short seta c. 2 / 3 of that of y a. A 2 (Fig. 3 B): Protopodal coxa with three setae (two ventrally, one laterally), protopodal basis with one long ventral subapical seta. Exopodite with three (one long, two short) setae, length of the long one reaching beyond tip of first endopodal segment. First endopodal segment with five long natatory setae (reaching tip of terminal claws) and one short accompanying seta (not reaching mid-length of next segment), aesthetasc Y thin, four-segmented, ventro-apical seta short and slender (not reaching tip of penultimate segment). Penultimate segment undivided, distally with three serrated claws (G 1 – G 3), aesthetasc y 2 short (reaching tip of terminal segment), z 1 – z 3 setae long (not reaching tip of G claws); this segment medially with two (one long, one shorter) dorsal setae (length of short one c. 2 / 3 of that of the long one) and four ventral setae of unequal length (one larger than other three setae). Terminal segment with two serrated claws (GM and Gm), and aesthetasc y 3, g seta not seen, length of Gm c. 5 / 6 of that of GM, length of aesthetasc y 3 c. half of that of accompanying seta. Md coxa (Fig. 3 C) elongated distally, with rows of teeth and small setae (largest tooth set on dorsal side), and with one short dorso-subapical seta (not reaching row of teeth); the latter cone-shaped with flagellum-like tip. Md palp (Fig. 4 A, A '): first segment with two large setae (bearing long setules), one slender, long seta and smooth α seta; the latter subtriangular with long, needle-like tip. Second segment dorsally with three unequally long apical setae, length of shortest c. half of that of longest; ventrally with group of three long setae, one shorter hirsute seta and β seta, the latter plumose, short, broad and with pointed tip. Third segment consisting of three groups of setae: dorsally with group of four unequal, long, subapical setae; laterally with apical γ seta and three smooth apical setae, the former stout, plumose, subtriangular with long needle-like tip; ventrally with two (one long, one short) subapical setae, short one reaching tip of segment. Terminal segment bearing three claws and three setae. Mx 1 (Fig. 4 B) with two-segmented palp, three endites and large branchial plate; basal segment of palp with group of five long, unequal apical setae and two (one long, one short) subapical setae, the latter not reaching tip of terminal segment; terminal segment short (width and length subequal), apically with three claws and two setae. Two large bristles on third endite smooth. Two sideways-directed bristles on first endite unequally long. T 1 (Fig. 4 C, D): protopodite with two a setae (length of short one c. 2 / 3 of that of long one), long b and d setae, distally with 14 (10 apical, four subapical) hirsute setae of unequal length. Endopodite weakly built palp with three (one long, two shorter) apical setae, short ones not reaching mid-length of long one. T 2 (Fig. 5 A) with subequal, short and thin d 1 and d 2 setae. Second segment with short e-seta (not reaching mid-length of next segment). Third segment with long f seta (reaching tip of next segment). Fourth segment with short apical g seta, accompanying seta absent. Terminal segment with short h 1 seta, serrated claw h 2 and markedly short h 3 seta, length of h 2 longer than that of last three segments. T 3 (Fig. 5 B) cleaning limb. First segment with long d 1, d 2, dp setae (not reaching tip of next segment). Second segment with moderately long apical e seta (reaching half of next segment). Third segment with medially short f seta (not reaching tip of segment). Terminal segment with apical pincer and three setae, one remarkably short h 1 seta, one claw-like h 2 seta and one reflexed subapical h 3 seta, latter shorter than third segment. CR (Fig. 5 C) well-developed, robust, with large Ga and Gp, set with strong denticles, length of Ga more than half of that of ramus, Gp reaching mid-length of Ga; Sa thin and short (not reaching mid-length of Gp), Sp thin and short with needle-like tip (reaching slightly beyond tip of ramus). CR attachment (Fig. 5 D) stout, with two distal branches. Male unknown. Distribution. Dolerocypris rossettii sp. nov. has so far been recorded from two localities (a swamp and a reservoir) in Roi Et Province, northeast Thailand. Ecology. The new Dolerocypris species occurred in water bodies with temperature, pH and conductivity ranges of 29.7–30.8 ° C, 7.47–7.69 and 100–137 μS / cm, respectively. The substrates were mud with a small to moderate amount of organic matter. The sampling sites contained a few aquatic plant species: Ipomoea aquatica Forssk. and Salvinia cucullata Roxb. ex Bory in the type locality (Kut Khaen) and Nelumbo nucifera Gaertn. and Neptunia oleracea Lour. in another locality (Nong Kae). The latter locality was dominated by Nelumbo nucifera, covering c. 50 % of the sampled area. Remarks. Dolerocypris rossettii sp. nov. is primarily characterized by the RV overlapping the LV anteriorly, and vice versa posteriorly. It cannot be confused with any other species in the genus. It also differs from its congener, D. fasciata, by a longer seta on the A 2 exopodite, the γ seta on the mandibular palp with a long needle-like tip, a short e seta on the second thoracopod, and shorter Sa and longer Sp setae on the CR.