Balticoniscus walterludwigi Kästle & Ludwig, 2025, gen. et sp. nov.

Balticoniscus walterludwigi gen. et sp. nov. urn:lsid:zoobank.org:act: BD4A386F-22AD-41FD-A7F5-03D7CAACD70F Figs 1–3 Diagnosis As for the genus vide supra. Etymology The species is named in honor of Walter Ludwig, who generously donated the amber to the Paleontological Collection of the University of Tübingen. Type material Holotype POLAND • ♀; Jantar; 1960s; W. Ludwig leg.; GPIT, GPIT-PV-108383. Description HABITUS. Maximum body length 4.2 mm. Pereon strongly convex, pleon less convex compared to pereon. Dorsum smooth with weakly rugose muscle spots and covered with small triangular scale setae (Fig. 1D). Scale setae 1.5 times as wide as long. CEPHALON. Cephalon 2.1 times as wide as long. Cephalon with frontal shield developed into wide medial lobe shortly protruding over vertex and occupying entire space between eyes (Fig. 2A–B, D). Antennary tubercles project strictly ventrally (Fig. 1A–B). Shallow transverse groove running along posterior margin of cephalon (Figs 1C, 2D). Eyes moderately large with at least 15 ocelli, half the length of cephalon in lateral view. Antennae short and relatively stout, not reaching posterolateral corner of first pereonite. Length to width ratio of second peduncle of antenna 1.3. Length to with ratio of third and fourth peduncle 1.7. Length to width ratio of fifth peduncle 4.5. Fifth peduncle 2.2 times as long as preceding peduncle and 1.4 times as long as flagellum. Flagellum two-segmented with distal article three times as long as proximal article and five times as long as wide (Fig. 2G). PEREONITES. Pereonites with weakly pronounced muscle spots, almost smooth (Fig. 3C–D). Epimera of pereonite I with convex lateral margin, posterior margin weakly concave. Posterolateral corner of epimera rounded, anterior corner acutely rounded (Fig. 2A). Epimera of pereonites II–VII quadrate with weakly rounded anterolateral corners. Posterior margins of pereonites I–V laterally weakly concave, successively more straight moving posteriorly. Posterior margins of pereonites VI–VII entirely straight (Fig. 2A). All pereonite epimera without ventral articulatory structures. PEREOPODS. Carpus of female pereopod 1 with sternal ridge-like projection present along entire length of carpus, reaching its apex at ⅔ of length of carpus (Fig. 2H). Pereopods 1–6 otherwise without particular modifications. PLEONITES. Epimera of pleonites 3–5 quadrate, with weakly pronounced posterolateral corner (Fig. 2A, C, F). Pleonite epimera 3–4 ventrally with transverse ridge to accommodate the succeeding segment. Pleonite epimera 5 with transverse ridge to accommodate uropod protopodite (Fig. 2F). PLEOPODS. Exopod of female pleopod 1 subtly triangular with rounded corners, twice as wide as long. Female pleopod exopod 2 subtly triangular with rounded corners, about as wide as long. Female pleopod exopods 3–5 sub-trapezoidal and laterally rounded (Fig. 2E). PLEOTELSON. Pleotelson triangular, as wide as long, with weakly concave lateral margins and not surpassing pleonite 5 posteriorly. Pleotelson strongly acute. UROPODS. Uropod protopodite cylindrical and short, not exceeding past posterior tip of pleotelson. Uropod endopodite moderately sized, 1.3 times as long as protopodite. Uropod exopodite small and conoid, 0.75 times as long as protopodite. Uropod endopodite and exopodite shortly protruding past posterior tip of pleotelson (Fig. 2C). Remarks The entire ventral side, the pleotelson, and the uropods are surrounded by numerous deep cracks, particles, as well as clouding, and could therefore only be examined via µCT-scan. Right pereopods 3–5 and 7, as well as left pereopods 6–7 appear to be preserved only basally, missing the majority of the leg (Fig. 3B). Even though most of the area surrounding the cephalon is obstructed as well, major parts of the antennae are visible (Fig. 1B–C). Some structures that are visible with light microscopy could not be retrieved in the volumetric rendering, notably the flagellum of the left antenna, as well as many small portions of the pereonites and pleonites, which resulted in small holes in the surface of the visualized specimen (compare: Figs 1 and 3). Due to this, it is possible that more of the pereopods is present than could be observed with the volumetric rendering. The preserved individual appears to be female, as no genital papilla and no pleopod endopodites are present. Given that the seventh pereonite is well-developed and the seventh leg, though only basally preserved, appears to have been well-formed and functional, the preserved individual had progressed beyond the postmarsupial manca stages. It was not possible to determine whether the individual was sexually mature. Syninclusions Two Nematocera Latreille, 1825, likely belonging to the family Sciaridae Billberg, 1820, are preserved in the amber as well (Fig. 1A). A more precise identification, or whether these individuals belong to an already described species, is not known at present.