Unio sella Haas, 1912

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 : 443-446

Unio sella Haas, 1912

( Fig. 3 A–G)

Unio sella Haas, 1912: 122 .

Unio laosensis Lea, 1863: 67 .

Margaritana laosensis – Simpson, 1900: 678.

Margaritanopsis laosensis – Haas, 1910: pl. 12.

Margaritifera laosensis – Haas, 1969: 13.

Gibbosula laosensis – Lopes-Lima et al., 2018: 112.

Taxonomic status. This name was introduced as a synonym of Gibbosula laosensis ( Margaritiferidae : Gibbosulinae ) ( Haas, 1912) and was never used as valid. Therefore this

name is not available (Art. 11.6 of ICZN). A junior synonym for Gibbosula laosensis .

Type locality. “Mti Carin 1300 m, Birmanien” [headwater of the Thauk Ye Kupt River , Sittaung Basin , western Karen Hills area, Myanmar] ( Figs. 1 , 2 ) .

Type series. Lectotype [larger shell, designated in this study] and paralectotype [smaller shell], NHMW no. 20080 ( Fig.

3A–D). Original label: “20080. Orig. 2. Unio sella Tapp. n. sp. (in lit.). Mti Carin 1300 m, Birmanien. L. Fea coll., Tapparone det.” ( Fig. 3E ). This sample is not dated, but Fea was collecting on the Karen Hills area during the period from 13 December 1887 to 11 April 1888 ( Fea, 1888).

Other samples (proposed topotypes). Two shells of Gibbosula laosensis illustrated by Prashad (1922): Pl. 2, Figs. 3 , 4 ; their current whereabouts are unknown (but see

discussion on the paratype of Unio sella Prashad, 1922 ). Recent samples of Gibbosula laosensis : 5 ethanol-preserved specimens, 55 dead shells and 28 dry valves, Myanmar: Sittaung Basin, Thauk Ye Kupt River, 19.3075° N, 96.7219° E, 20 April 2015, coll. Bolotov, Vikhrev and local villagers [ RMBH biv136]; 3 ethanol-preserved specimens, same locality, 7 December 2016, coll. Vikhrev [ RMBH biv271].

Etymology. The Latin (and Italian) word “sella” means “saddle”, most likely a reference to the arcuate shell shape of this species.

Figures

Fig. 3. Types of Unio sella Haas, 1912 [=Gibbosula laosensis] (NHMW 20080) and proposed topotype of this taxon (RMBH biv136/21). A, B, lectotype [designated in this study], larger shell, lateral view. A, inner side of the left valve and outer side of the right valve; B, vice versa. C, D, paralectotype, smaller shell, lateral view. C, inner side of the left valve and outer side of the right valve; D, vice versa. Scale bar = 20 mm. E, original label [probably by C.M. Tapparone-Canefri]. F, G, shell of proposed topotype from Thauk Ye Kupt River, lateral view. F, inner side of the left valve and outer side of the right valve; G, vice versa. Scale bar = 10 mm. (Photos: NHMW/A. Schumacher, with permission of Anita Eschner [A–E] and Ekaterina Konopleva [F–G]).

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).

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]).