Sayamia sexpunctata ( Lanchester, 1906 )

Ng, Peter K. L., , Martyn E. Y. Low, Clark, & Paul F., 2022, Historical notes on various collectors of unidentified freshwater crabs (Crustacea: Decapoda: Brachyura) from the Malay Peninsula and Borneo, with descriptions of two new species of Isolapotamon Bott, 1968 Potamidae), Raffles Bulletin of Zoology 70, pp. 550-571 : 565

Sayamia sexpunctata ( Lanchester, 1906)

Potamon (Paratelphusa) sexpunctata Lanchester, 1906: 29 , fig. 7. Somanniathelphusa juliae Bott, 1968: 408 , figs. 7, 8, 28.

Material examined. 2 females ( NHM 1898.1.17.5–6), “ Takkom , Siam ”, coll. Capt. S.S. Flower, 1 April 1897, in exchange with Capt. S.S. Flower .

Remarks. The taxonomy of the species has been clarified by Ng & HP Ng (1987) and they argued that Somanniathelphusa juliae Bott, 1968 , is a junior synonym of Parathelphusa sexpunctata Lanchester, 1906 . Lanchester (1906: 129) described his species from two females from “Sai kau, Nawngchik” and “Cape Pattani ” in southern Thailand; while S. juliae was from Perlis in northern Malaysia ( Bott, 1968b: 408). The present specimens are from near the localities of Lanchester in southern Thailand and had been collected several years earlier by Capt. S.S. Flower but, for whatever reason, were not examined. Incidentally, Bott (1968b) had mistakenly synonymised the Lanchester species with S. germaini ( Rathbun, 1902) (see Ng & Naiyanetr, 1993).

Some comments on the bottle of specimens associated with registration number “1898.1.17.4–6” are necessary. The outside jar label and NHM Crustacea Register state “ Telphusa Brunei, Borneo”. This, however, conflicts with field-written labels attached to three of the crabs which appear not to have been considered by Jeffrey Bell (see Ingle, 1991) when registered on the 17 th of January 1898. On the leg of one female is tied a label stating “77, Bangkok, Siam, coll. Capt. S.S. Flower, July 1897 ”, this specimen is now registered as NHM 1898.1.17.4 and it is S. bangkokensis as now understood (cf. Naiyanetr, 1982, 1994; Ng & Naiyanetr, 1993). On the legs of two other female specimens (which were originally tied together) is a label stating “Takkom, Siam, coll. Capt. S.S. Flower, 1 April 1897 ”, these now have been allocated the registration number 1898.1.17.5–6 and identified here as S. sexpunctata ( Lanchester, 1906) . Furthermore, Sayamia is not known from Borneo. Although the registration number 1898.1.17.4–6 indicates there are only three specimens in the bottle, four are actually present. The fourth specimen in the 1898.1.17.4–6 jar is an ovigerous female, and here identified as the sesarmid Fasciarma fasciatum ( Lanchester, 1900) (see later). This crab does not have a label tied to it, consequently the locality is unknown but it is assumed to be somewhere in Siam ( Thailand). Additionally, under the Zoological Accessions, Crustacea Register number 1898.1.17.4–6 is stated “In exchange with S.S. Flower Esq.”