Eogmelina moldavica, Copilaş-Ciocianu & Ionesi, 2024

Copilaş-Ciocianu, Denis & Ionesi, Viorel, 2024, New Miocene fossil taxa illuminate the evolution and paleobiogeography of the Ponto-Caspian gammaroid amphipod radiation, Contributions to Zoology 93, pp. 268-288 : 276-278

† Eogmelina moldavica gen. et sp. nov. ( fig. 5 )

Zoobank LSID urn:lsid:zoobank.org:act:9447 24CC- 1883 -4F9E-B000-F590F254163E

Type material. Holotype (inventory No. 8236 , Vlădiceni quarry) male in precopulatory pair, 14.6 mm, lateral impression ( fig. 5A ). Paratype (inventory No. 8236 , Vlădiceni quarry) female in the same precopulatory pair, 12.4 mm, lateral impression ( fig. 5A ). Additional material: male (inventory No. 8237 part and counterpart, Vlădiceni quarry), 18.8 mm, lateral impression ( fig. 5B ); female (inventory No. 8238 , Iași City), 15.44 mm, lateral impression ( fig. 5C ); female (inventory No. 8239 part and counterpart, Vlădiceni quarry), ca. 11.2 mm, dorso-lateral impression ( fig. 5D ).

Type locality and age. Vlădiceni quarry (47.13442 N, 27.65734 E), Cryptomactra Formation , Tortonian international stage/ Bessarabian regional stage, ca. 10.5 Ma ( fig. 1C ).

Etymology. The specific epithet moldavica is in reference to the Moldova region of Romania.

Diagnosis. Differs from the only other currently known congener, † Eogmelina prisca gen. et sp. nov. by the presence of a spine on the dorso-posterior margins of the last pereonite and all three pleonites (vs. absent), coxal plate 1 as tall as the corresponding tergite (vs. taller), coxal plate 4 longer than broad (vs. roughly as long as broad).

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General description. Body. Large and robust gammarid (up to 22 mm). A dorsal spine is present on the last pereonite segment as well as on each of the three pleonites. Head length subequal to the combined length of the following two pereonites, lacking rostrum, antennal sinuses superficial, of similar depth. Coxal plates I-IV taller than wide, as tall as the corresponding tergal segments. Epimere 1 distal margin rounded, epimeres 2–3 disto-posterior corner pointed. Urosomites free and flat, devoid of tubercles or spines. Antennae. Antenna 1 reaches 0.3 body length, peduncle is robust and short, subequal to head length, not reaching the distal end of the 4th peduncular article of antenna 2. Peduncular segment 1 subequal to the combined length of segments 2 + 3. Main flagellum longer than peduncle. Accessory flagellum well developed, at least 3-articulated. Antenna 2 longer than antenna 1, reaching 0.35 body length. Peduncle well developed, longer than head and flagellum. Gnathopods. Propodi of both gnathopods rectangular, similar in length and shape, moderately developed (0.1 of body length), palm length subequal to posterior margin. Pereopods. Pereopods 3–4 subequal in length and of similar construction, carpus linear, longer than broad, without signs of expansion. Pereopods 5–7 well developed and robust (at least 0.4 of body length), bases taller than broad, without posterior lobes, propodi subequal to carpi, dactyli moderately developed and relatively straight. Coxae 5–7 progressively smaller posteriorly, poorly visible. Uropods. Uropod 1 rami subequal, shorter than peduncle, of senticaudatan type. Uropod 2 poorly visible, but shorter than uropod 1. Uropod 3 well developed (0.15 of body length), reaching well beyond the distal end of uropod 1, both rami lanceolate longer than peduncle, endopod reaching 0.9 exopod length. Sexual dimorphism. Typical of gammarid amphipods. Females are smaller than males, have more developed coxal plates and smaller gnathopod propodi ( fig. 5 ).

Figures

FIGURE 1 Paleogeographic and geological setting.A) Map of the Ponto-Caspian region. The area marked with transparent white indicates the maximum extent of the Paratethys 11 Ma ago (Palcu et al., 2021).The green dot represents the newly discovered fossil amphipod sites from Romania, while the black dots indicate previously known fossiliferous locations from the Caucasus (Azerbaijan and Russia).B) Close-up map of Iași City, Romania, (https://www.openstreetmap.org /#map=12/47.1449/27.6062) showing the location of the study sites (Site 1 – construction site in Iași City; Site 2 – Vlădiceni quarry).C) Upper part shows a chronostratigraphic chart of the Eastern Paratethys and its correlation to the Global Time Scale (Raffi et al., 2020).The stratigraphic age of the sites from this study are indicated with green, while the previously known sites from the Caucasus are indicated with black.The lower part is a geological cross section of the focal area indicating the lithostratigraphic context and altitude (modified after Ionesi et al. 2005). Sampling sites are indicated with green dots. D) Photographs of the two study sites from the current study. PHOTO BY IONESI V.

FIGURE 5 †Eogmelina moldavica gen. et sp. nov.On the right are interpretative drawings of the corresponding fossils on the left.(A) Holotype male and paratype female (inventory No. 8236,Vlădiceni quarry), (B) male (inventory No.8237,Vlădiceni quarry), (C) female (inventory No.8238, Iași City), (D) female (inventory No.8239, Vlădiceni quarry).Scale bars = 1 mm. Abbreviations:A = antenna; B = basis; C = coxa; G = gnathopod; H = head; P = pereonite; PL = pleonite; PP = pereopod; U = urosomite; UP = uropod; T = telson.