Elpidium alarconi Mesquita-Joanes, Gálvez, Palero & Rueda, 2025, sp. nov.

Elpidium alarconi sp. nov. Figs 1, 2, 3, 4, 5, 6, 7 Type locality. Rancho Baiguate (La Joya Sector, Jarabacoa, República Dominicana) 19°6'49"N, 70°37'8"W, 530 m a. s. l., sampled on 7/2/2019 and 12/4/2021 by J. Rueda and P. Alarcón. Tank bromeliads growing at the base of several tree trunks in a secondary natural forest, with a wide cover, and presence of domestic animals (horses, dogs) in the vicinity, near the Baiguate River. Type material. Holotype • 1 adult ♂; soft parts dissected and stored on a permanent microscopic slide, valves dry in a micropaleontological slide (MUVHNZY 0021). Allotype • 1 adult ♀; soft parts dissected and stored on a permanent microscopic slide, valves dry in a micropaleontological slide (MUVHNZY 0022). Paratypes • 10 adult ♂♂ and 17 adult ♀♀. Six of the males (MUVHNZY 0023 - MUVHNZY 0026, MUVHNZY 0035, MUVHNZY 0036) dissected and stored as the holotype, valves coated and used for SEM; one male (MUVHNZY 0027) used in toto for SEM, after applying critical-point drying (CPD), and stored in a micropaleontological slide; another male (MUVHNZY 0039) with valves untreated and bodies (CPD and coated) in a micropaleontological slide. Seven females (MUVHNZY 0028 -0033, MUVHNZY 0037) dissected and stored as the holotype, valves coated and used for SEM; another female (MUVHNZY 0038) with valves untreated and bodies (CPD and coated) in a micropaleontological slide. Two adult males and six females stored in toto in ethanol 96 % (MUVHNZY 0034). Soft body remains of three adult females used for DNA extraction stored in ethanol (codes MUVHNZY 0040 -0042). Diagnosis. Elpidium species of intermediate size (~ 700–800 μm), with a dark-colored carapace. Females slightly longer and wider than males, and with a truncate posterior margin in dorsal view; males with a barely obtuse posterior margin. Valves (quasi-) symmetric in dorsal view. Surface of valves covered with minute and shallow pits. LV embracing RV along all free margins. Hinge protodont, with a strongly built bar in the RV, including one (proto-) tooth at each extreme of the bar. LV with a hinge groove. A 1 apparently six-segmented (i. e., segments 4 a and 4 b partially separated). DL of male Hp with a long digital expansion, CoP L-shaped, with tip not subdivided, and LR very slender (thinner than CoP), L-shaped and with a pointed tip. Description. Male. Adult shell large (L> 0.7 mm), according to size groups established for limnocytherids s. l. by Gidó et al. (2007), but of intermediate size compared to other Elpidium species. Cp subovate in dorsal and ventral view (Fig. 1 A, B). Maximum width slightly displaced to posterior part, at ~ 45 % of total length. Cp in dorsal view: anteriorly pointed, barely acute; posteriorly bluntly pointed, obtuse, with more rounded outline than anterior margin. Valves almost symmetrical in dorsal view; LV slightly longer and embracing RV along all free margins (Fig. 1 B). Valves elongate in lateral view (Fig. 1 C, D), posterior margin broadly rounded, anterior margin infracurvate, i. e., narrowly rounded towards anteroventral region. Maximum length at ~ 33 % of maximum height. Ventral margin slightly convex in lateral view, flat in ventral (Fig. 1 B) and frontal (Fig. 5 A) views. Surface of valves smoothly punctate, overall covered with minute foveolae and sparsely with normal (type- A 2) pores, many of which hold a sensory seta (Fig. 1 A, C, D, I – K). These foveolae more conspicuous, denser, and deeper near anterior margin of valves, in a narrow beak-like zone (Fig. 1 K). This zone partially corresponds internally to the area of the inner lamella between outer margin and selvage (Fig. 1 E, F). Calcified inner lamella wider anteriorly (~ 12 % of valve L) than posteriorly (6 % of valve L). Selvage strongly built in the RV (Fig. 1 F, H), anteriorly positioned approximately half way between anterior margin and inner margin of calcified inner lamella. Hinge protodont, sensu Danielopol et al. (2014). RV dorsally with a hinge bar (Fig. 1 H), showing anterior and posterior prototeeth. LV with a hinge groove (Fig. 1 G), anteriorly with enlarged socket. Both valves antero-ventrally with selvage protruding towards external margin, building the typical funnel-like structure of Elpidium ostracods at mouth position. Four large adductor muscle scars (Fig. 1 F, L) aligned in a slightly oblique row (leaning 30 ° from vertical axis towards anterior part, from top to bottom), located just in front of central area of valves. Three of these scars elongate, bottom one subovate. Another smaller, rounded scar situated in front of top one of the four central muscle scars. Both valves postero-ventrally with a row of submarginal (type- A 2) pores and setae located in the peripheral part of the marginal infold (Fig. 1 I, J). Carapace colored dark brown. A 1 (Figs 2 A, 3 A – D). Apparently six-segmented, i. e., with clear separation between segments 4 a and 4 b under standard microscope, but this separation weaker than other segments (Fig. 3 A). Separation not observed under UV-light in a fluorescence microscope, compared to other segmentation (Fig. 3 B). This separation observed only in the internal part of fourth segment under SEM, but not in the external part (Figs 3 C, D, 5 E). First segment trapezoidal, strongly built, dorsally with a subapical subtriangular expansion, partially covered with pseudochaetae. Second segment elongate, more than thrice longer than wide, dorsally covered with pseudochaetae along its margin, ventrally with a long plumose seta, attached slightly behind middle of segment, and reaching mid-length of fourth segment. Third segment rectangular, with a seta at its dorso-apical margin, this seta slightly longer than next segment. Segment 4 a rectangular, ~ 2 × longer than wide, dorsally with two small apical setae (not attaining the middle of next segment) and ventrally one seta as long as next segment. Fifth segment (segment 4 b) dorsally with three apical setae of varied length; longest one attaining one third of Ya aesthetasc, second longer one as long as last segment, smallest one ~ 1 / 2 the length of last segment. Ventrally with a long apical seta, surpassing the middle of Ya aesthetasc. Last (sixth) segment with three apical setae and Ya aesthetasc. One seta as long as Ya, another slightly longer than last two segments, another one slightly longer than last three segments. A 2 (Fig. 2 B). Protopod two-segmented. First segment short and ring-shaped, second segment elongate and smoothly curved,> 2.5 × longer than wide. Exopod with a very small seta and a spinneret seta, not surpassing tip of claws. First segment of endopod subquadrate, ventrally with an apical long seta, ~ 2 / 3 of the length of next segment. Second endopodal segment elongate, ~ 5 × longer than wide. Ventrally with one small seta and Y aesthetasc, situated slightly in front of mid-length of segment. This small seta slightly shorter than aesthetasc. Another large and thick seta attached to ventro-apical margin, together with a minute seta (Fig. 5 F, as in the female: Fig. 3 E). Dorsally with two subapical short setae, one ~ 1 / 2 the length of the other. Last segment subquadrate, with three claws, shortest and ventral one pectinated with a row of strong teeth (Fig. 5 F). A very small hyaline formation located ventro-apically, at the base of pectinated claw, but together with a minute seta (as in the female: Fig. 3 F). Md (Fig. 2 C). Coxa slender, with curved posterior half and straight anterior one. Distally with eight teeth, progressively smaller from anterior (dorsal) to posterior (ventral) ones, most of them bicuspidate and / or with adjacent interdental spines and setae (X-setae). Dorsally with large serrate seta, not reaching the base of dorsal teeth. Ventrally with one small plumose seta, slightly longer than ventralmost small tooth. Md-palp four-segmented and curved. First segment (basis) with two ventral plumose setae, one ~ 2 / 3 the length of the other. Dorsally with exopod (respiratory plate) with three broad rays and a small reflected ray. Second segment (first endopodal segment) with two ventro-apical plumose setae, one of them half the length of the other. Third segment subquadrate, ventrally holding an apical long smooth seta, dorsally with three long apical smooth and thin setae, together with a thicker plumose seta, all of similar length. Last segment small and subquadrate, with three terminal thin setae of similar length, one of these claw-like, the other two smooth. Mx (Fig. 2 D). Elongate, subrectangular protopod. Exopod (respiratory plate) with 16 distal unequal rays and a proximal reflexed ray. Endopod with three endites and a palp. First endite with three subequal setae. Second and third endites each with two spoon-shaped (spatulate), claw-like setae, and three smooth, thin setae. Palp unsegmented, distally with two long plumose setae, longer than tip of endite setae, plus a minute subapical dorsal seta. T 1 (Figs 4 A, 5 H). Four-segmented. First segment the longest. Ventrally with a large seta, situated well behind mid-length of segment. Dorsally with proximal long seta, slightly surpassing distal margin of segment. Dorso-apically with two subequal knee-setae. Second segment elongate, 6 × longer than wide, ventrally with strong apical seta, as long as next segment. Third segment without setae. Fourth segment with apical claw bearing a minute seta at its swollen base, and as long as third segment. T 2 (Figs 4 B, 5 H). Larger than T 1 and four-segmented. First segment strong, bearing ventrally a subproximal long setae, attaining distal edge of segment. Dorsally with one medial long seta, surpassing distal margin of segment, and an apical knee-seta, ~ 1 / 2 the length of previous seta. Second segment slender and long, ventrally with apical strong seta, almost as long as next segment. Third segment without setae. Fourth segment similar to previous one but slightly shorter and with an apical claw. This claw as long as third