Unio sella Prashad, 1922

Bolotov, Ivan N., Vikhrev, Ilya V., Lopes-Lima, Manuel, Gofarov, Mikhail Y., Konopleva, Ekaterina S., Lyubas, Artem A., Lunn, Zau, Chan, Nyein & Bogan, Arthur E., 2019, Unio sella and U. sula: A review of enigmatic taxonomic names linked to Gibbosula laosensis (Lea, 1863) (Bivalvia: Margaritiferidae: Gibbosulinae), Raffles Bulletin of Zoology 67, pp. 440-447 : 446

Unio sella Prashad, 1922

( Fig. 4 A–H)

Unio sella Prashad, 1922: 93 , pl. 2, figs. 1, 2.

Trapezoideus nesemanni Konopleva, Vikhrev & Bolotov in Bolotov et al., 2017a: 13 , fig. 4c, tables 3, S1.

Yaukthwa nesemanni – Konopleva et al., 2019: 7.

Taxonomic status. This name was introduced as a synonym of Gibbosula laosensis ( Margaritiferidae : Gibbosulinae ) ( Prashad, 1922) and was never used as valid. Therefore this name is not available (Art. 11.6 of ICZN). A primary junior homonym of Unio sella Haas, 1912 and a senior synonym for Yaukthwa nesemanni ( Unionidae : Rectidentinae : Contradentini ).

Type locality. “Carin independ. 1000–1200 m ” [headwater of the Thauk Ye Kupt River , Sittaung Basin , western Karen Hills area, Myanmar] ( Figs. 1 , 2 ) .

Type series. Lectotype in MSNG [designated in this study], without ID number ( Fig. 4 A–C). Original label: “ Unio sella Tapp. n. sp. (in lit.). Carin independ. 1000–1200 m ” ( Fig. 4D ). Secondary labels: “ Margaritanopsis laosensis (Lea) . detto B. Prashad” and “ Margaritanopsis laosensis (Lea) .” ( Fig. 4E, F ). This shell was illustrated by Prashad (1922): Pl. 2, Fig. 1 . The sample is not dated, but Fea was collecting in the Karen Hills during the period from 13 December 1887 to 11 April 1888 ( Fea 1888). Paralectotype: illustrated by Prashad (1922): Pl. 2, Fig. 2 , but its current whereabouts are unknown. Prashad (1922: 92) noted that “I applied to Dr. R. Gestro of the Genoa Museum. He was not only kind enough sent me the whole of Fea’s Burmese collection on loan, but also generously presented to the Indian Museum specimens of a number of the species, duplicates of which were still available”. Based on this note, we could assume that the paralectotype of Unio sella Prashad, 1922 is deposited in the malacological collection of the Zoological Survey of India, Kolkata.

Other samples (proposed topotypes). Holotype of Yaukthwa nesemanni : Myanmar: Sittaung Basin , Thauk Ye Kupt River, 19.3075° N, 96.7219° E, 26 November 2016, coll. Vikhrev [ NCSM 103033 ] . Paratypes of Yaukthwa nesemanni : 4 specimens, same locality, 20 April 2015 and 26 November 2016, coll. Bolotov, Vikhrev and local villagers [ RMBH biv255_3, biv144_14, biv144_25, and biv144_19] .

Figures

Fig. 4. Lectotype of Unio sella Prashad, 1922 [=Yaukthwa nesemanni] (MSNG, without ID number) and proposed topotype of this taxon (NCSM 103033). A, B, lectotype [designated in this study], lateral view. A, inner side of the left valve and outer side of the right valve; B, vice versa. C, lectotype, dorsal view. Scale bar = 5 mm. D, original label of the lectotype [probably by C.M. Tapparone-Canefri]. E, F, secondary labels of the lectotype [probably by B. Prashad]. G, H, shell of proposed topotype from Thauk Ye Kupt River, lateral view. G, inner side of the left valve and outer side of the right valve; H, vice versa. Scale bar = 10 mm. (Photos: Ilya Vikhrev [A–F] and Ekaterina Konopleva [G–H]).

Fig. 1. Karen Hills area. A, map of Myanmar with the geographic position of the Karen Hills area (red frame); B, map of the Karen Hills area with the boundaries of freshwater subregions, collecting localities and historical information. The red line indicates boundary of the Karen Hills area sensu Leonardo Fea (1888). The blue line indicates the Sittaung – Salween drainage divide, separating the western and eastern subregions of the Karen Hills area. The violet line indicates the putative route of Leonardo Fea’s expedition in the years 1887–1888 (Fea 1888; topographic map no. E47-1 by The General Staff of the USSR, scale = 1:500,000). The red star indicates our locality on the Thauk Ye Kupt River, from which Unio sella Haas, 1912 [=Gibbosula laosensis] and U. sella Prashad, 1922 [=Yaukthwa nesemanni] were rediscovered. The red circles indicate two highland research stations of Leonardo Fea in the western Karen Hills: “Jaddo (Yado) Valley” (ca. 30 mi NE of Taungoo, alt. ca. 900–1,000 m a.s.l.), and “Taho (Thao) village” (ca. 7–8 mi N of “Jaddo Valley”, alt. ca. 1,200–1,300 m a.s.l.) (Fea, 1888). The purple frame indicates the boundary of area in which the type localities of Unio sella Haas, 1912 [=Gibbosula laosensis] and U. sella Prashad, 1922 [=Yaukthwa nesemanni] were situated. (Map: Mikhail Yu. Gofarov).

Fig. 2. Thauk Ye Kupt River, western Karen Hills, proposed type locality for Unio sella Haas, 1912 [=Gibbosula laosensis] and U. sella Prashad, 1922 [=Yaukthwa nesemanni]. (Photo: Ilya Vikhrev).