Dioryx dongiensis Varga 1972

Information from the abstract

Dioryx dongiensis Varga, 1972 Fig. 2 B Dioryx dongiensis Varga, 1972: 135, 137, figs 21–23. Type locality: Vietnam, Tonkin, Cuc Phuong bei Dong [Cuc Phuong, Ninh Binh]. Páll-Gergely et al. 2020 d: 125. von Oheimb et al. 2025: tables 1, 3, 4, fig. 8 h. Material examined. Laos • 1 shell; Vientiane Province, Feuang District, limestone hill behind Xinxayyaram Temple (loc. MF 10); 18°33'00.5"N, 101°58'30.8"E; 265 m a. s. l.; 9 Oct. 2024; leg. CU - NUOL expedition team; CUMZ 14476 (Fig. 2 B). Diagnosis. Shell conical, globular. Spire ~ 30 % of shell height. Protoconch smooth. R 1 ~ 3 ½ whorls, sculptured with indistinct spiral striation. R 2 ~ ¼ whorl, with thin ribs; the end of R 2 slightly narrower. Peristome double with expanding outer peristome; totally adnate to the last whorl. Umbilicus slightly open. Differential diagnosis. Dioryx dongiensis is different from D. kobeltianus (Möllendorff, 1874) in having a shallower umbilicus with a less pronounced edge of the last whorl’s lower periphery. In addition, the peristome of D. kobeltianus is not totally adnate to the last whorl (Páll-Gergely et al. 2017). Distribution. The type locality (von Oheimb et al. 2025), and Feuang District, Vientiane Province, Laos. Remarks. This is the first record of Dioryx dongiensis in Laos, apart from the type locality in Vietnam (von Oheimb et al. 2025). Although the locality in Laos is more than 400 km away from the type locality, this shell is herein identified to this species based on its shell shape and the peristome totally adnate to the last whorl. Moreover, several Alycaeinae species have a wide distribution from Vietnam to Laos (e. g., Dicharax depressus; Páll-Gergely et al. 2017). As the shell of this species is very small, soil sieving and floatation methods (Liew et al. 2008) are preferred to retrieve more shells, and this species might be collected from more localities located between Vietnam and Laos. See earlier taxonomic treatment of Dioryx dongiensis in Páll-Gergely et al. (2020 d).

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Related topics: Diatoms and Algae Research · Marine Biology and Ecology Research · Mollusks and Parasites Studies