Pseudobaphia biesiana ( Heude, 1877 )

Bogan, Arthur E. & Do, Van Tu, 2018, An overlooked new species of freshwater bivalve from northern Vietnam (Mollusca: Bivalvia: Unionidae), Raffles Bulletin of Zoology 66, pp. 78-86 : 80

Pseudobaphia biesiana ( Heude, 1877)

( Fig. 2 )

Type locality. “Le torrent de Ning-kouo-hien.” Johnson (1973) and Graf & Cummings (2017) placed this locality in Anhui Province in the Yangtze and Huai River basins in eastern People’s Republic of China.

Type materials. Syntypes: MNHN 3425 , MNHN 3427 ; SMF 3597 ( Graf & Cummings, 2017) ; USNM 126480 [2 specimens] (Smithsonian Institution Database, 14 August 2017) [listed as paratypes by Johnson, 1973] .

Other materials. NZMC FM 01681 ( He & Zhuang, 2013: 89).

Discussion. There are no known preserved specimens available for anatomy or molecular analyses for P. biesiana . It is only known from five dry shell specimens. The specimen NZMC FM 01681 from Sichuan province, People’s Republic of China figured by He & Zhuang (2013) is identified as P. biesiana , but differs from the illustrated syntypes ( Fig. 2 ) in having two short lateral teeth in the left valve. This specimen has greater lateral tooth development than exhibited by the syntype specimens and is from much farther west in China. It appears to be morphologically between P. biesiana and P. banggiangensis new species, which has well developed, long lateral teeth. This specimen may represent another new species in Pseudobaphia , but more specimens are required to answer this question. Historically, Haas (1969a, b) placed Pseudobaphia in the Quadrulinae , but modern molecular analyses restrict this subfamily to North America and it does not include any Asian taxa ( Lopes-Lima et al., 2017). The phylogenetic position of Pseudobaphia is assumed to be in Unionidae , but assignment to subfamily or tribe is not now possible and is currently listed as Unionidae (incertae sedis) ( Graf & Cummings, 2007; Lopes-Lima et al., 2017; Zieritz et al., 2017). Live specimens of this species are required to answer the question of Pseudobaphia ’s phylogenetic position.

Description. “Shell large, rather solid, inflated, subrhomboid, somewhat equilateral; beaks very full and high, corrugated; ligament large, brown; posterior ridge more or less double, ending in a biangulation at and below the median line, the region above it obliquely truncate; epidermis fuscousolivaceous, slightly rayed when young; surface smooth and shining medially; pseudocardinals strong, stump, slightly roughened, showing behind them numerous nodules; lateral feeble, in old shells almost wanting; anterior scars deep in the hinder portion; posterior scars large; beak cavities deep, compressed; nacre dirty white or flesh-colored. Length 106, height 76, diam. 52 mm.” Simpson (1914: 1139).

Figures

Fig. 2. Unio biesianus Heude, 1877. Heude, 1877: plate 14, figure 30.