taxonID	type	description	language	source
C010EF62FFCA683CFAE7FE73FDACFBFA.taxon	materials_examined	Type species. Potamon kanchanaburiens e Naiyanetr, 1992, by present designation. Diagnosis Carapace distinctly broader than long, dorsal surface relatively ¯ at. Epigastric cristae well-developed, rugose, almost level with postorbital cristae, separated from postorbital cristae by short, narrow groove; postorbital cristae rugose. External orbital angle triangular; epibranchial tooth distinct, triangular; anterolateral margins strongly convex; posterolateral margins strongly convergent posteriorly; branchial region granulose to rugose; metabranchial region with oblique striae. Ischium of third maxilliped rectangular; exopod exceeding distal margin of ischium, with welldeveloped ¯ agellum. Ambulatory legs normal, not elongate. Suture between thoracic sternites 3 and 4 not visible. Male abdomen triangular. G 1 stout, slightly sinuous; terminal segment long, stout, twisted along longitudinal axis, with groove for G 2 clearly visible from ventral view, subdistal part appearing pectinated, surrounded by short, stiOE setae. G 2 distal segment greater than half length of basal segment. Remarks	en	Yeo, D. C. J., Naiyanetr, P. (2000): A new genus of freshwater crab (Crustacea: Decapoda: Brachyura: Potamidae) from Thailand, with a description of a new species. Journal of Natural History 34 (8): 1625-1637, DOI: 10.1080/00222930050117521, URL: http://www.tandfonline.com/doi/abs/10.1080/00222930050117521
C010EF62FFCA683CFAE7FE73FDACFBFA.taxon	description	The G 1 form of Stelomon also appears super ® cially similar to that of certain Malayopotamon species [Java, Sumatra], e. g. M. brevimarginatum (De Man, 1892), but the two genera can still be diOEerentiated by the position of the groove for the G 2 on the terminal segment of the G 1 (ventral in Stelomon versus dorsal or marginal in Malayopotamon) (Ng and Naiyanetr, 1993: 8). The G 1 of Stelomon species also resembles that of Stoliczia chaseni (Roux, 1934) [Peninsular Malaysia] but the latter species does not have a ¯ agellum on the third maxilliped exopod, and their carapace features diOEer considerably (Ng and Naiyanetr, 1993: 8; Ng, 1988 b: 64).	en	Yeo, D. C. J., Naiyanetr, P. (2000): A new genus of freshwater crab (Crustacea: Decapoda: Brachyura: Potamidae) from Thailand, with a description of a new species. Journal of Natural History 34 (8): 1625-1637, DOI: 10.1080/00222930050117521, URL: http://www.tandfonline.com/doi/abs/10.1080/00222930050117521
C010EF62FFCA683CFAE7FE73FDACFBFA.taxon	etymology	Etymology The genus name is derived from the Latin word, stela, meaning pillar or column, in arbitrary combination with the genus name Potamon, alluding to the proportionatel y long and stocky G 1 terminal segment characteristic of this genus. Gender neuter. Distribution	en	Yeo, D. C. J., Naiyanetr, P. (2000): A new genus of freshwater crab (Crustacea: Decapoda: Brachyura: Potamidae) from Thailand, with a description of a new species. Journal of Natural History 34 (8): 1625-1637, DOI: 10.1080/00222930050117521, URL: http://www.tandfonline.com/doi/abs/10.1080/00222930050117521
C010EF62FFCD683FFA1FFBBBFC95FE61.taxon	materials_examined	Material examined HOLOTYPE: male (62.4 Ö 47.7 mm) (RMNH D 42352), Sai Yok Noi waterfall, Sai Yok District, Kanchanaburi Province, Thailand, coll. P. Naiyanetr, 7 March 1976. PARATYPES: one female (44.2 Ö 34.0 mm) (ZRC 1991.1835), same data as holotype. one male, one female (male 55.1 Ö 41.8 mm) (RMNH D 41616), same locality and collector as holotype, 19 July 1981. Others. Eight males, four females (largest male 59.5 Ö 44.3 mm) (ZRC 1998.114 2), one male, one female (male 52.7 Ö 37.9 mm) (ZRC 1995.43 7), 25 males, 35 females (largest male 61.7 Ö 44.2 mm) (CUMZ), Thong Pha Phum District, Kanchanabur i Province, Thailand, coll. S. Panha and C. Ekavibhathai, 17 November 1991. Two males (larger 42.8 Ö 33.0 mm) (ZRC 1998.1143), two males (larger 51.9 Ö 39.3 mm) (CUMZ), Ban Huay Ka Yeng, Thong Pha Phum District, Kanchanaburi Province, Thailand, coll. S. Phitsaksindhorn, October 1997. Four males (largest 45.9 Ö 35.0 mm) (ZRC 1998.114 4), Nam Chon waterfall, Si Sawat District, Kanchanaburi Province, Thailand, coll. P. Naiyanetr, 24 November 1990. Remarks	en	Yeo, D. C. J., Naiyanetr, P. (2000): A new genus of freshwater crab (Crustacea: Decapoda: Brachyura: Potamidae) from Thailand, with a description of a new species. Journal of Natural History 34 (8): 1625-1637, DOI: 10.1080/00222930050117521, URL: http://www.tandfonline.com/doi/abs/10.1080/00222930050117521
C010EF62FFCD683FFA1FFBBBFC95FE61.taxon	description	The present specimens also show variation in the narrowed distal part of the G 1 terminal segment. The left G 1 of the holotype has a distinctly outwardly hooked distal part with a relatively sharp tip although its right G 1 ® gured by Ng and Naiyanetr (1993: ® gures 34 B ± E) is not hooked but slightly bent distally with a rounded tip. This diOEerence is probably due to the distal part of the right G 1 being worn down by abrasion possibly during mating. All the other specimens examined, including paratypes, have G 1 s with the distal parts hooked outwards to varying degrees and tips being sharp or rounded (® gures 2 B ± H). The degree of twist of the terminal segment also varies slightly among individuals but the distal opening remains more or less lateral-facing in position (® gures 2 E ± H). The distinctive hooked structure is present even in the smallest adult male specimen (35.2 Ö 26.4 mm) (ZRC 1998.114 2) and is, therefore, very diagnostic for S. kanchanaburiens e.	en	Yeo, D. C. J., Naiyanetr, P. (2000): A new genus of freshwater crab (Crustacea: Decapoda: Brachyura: Potamidae) from Thailand, with a description of a new species. Journal of Natural History 34 (8): 1625-1637, DOI: 10.1080/00222930050117521, URL: http://www.tandfonline.com/doi/abs/10.1080/00222930050117521
C010EF62FFCE6833FA46FE44FDD9FD2E.taxon	materials_examined	Material examined LECTOTYPE: male (27.4 Ö 21.2 mm) (ZSI 5531 / 10), Hills between Burma and Siam, coll. and date unknown.	en	Yeo, D. C. J., Naiyanetr, P. (2000): A new genus of freshwater crab (Crustacea: Decapoda: Brachyura: Potamidae) from Thailand, with a description of a new species. Journal of Natural History 34 (8): 1625-1637, DOI: 10.1080/00222930050117521, URL: http://www.tandfonline.com/doi/abs/10.1080/00222930050117521
C010EF62FFCE6833FA46FE44FDD9FD2E.taxon	description	PARALECTOTYPE: female (31.2 Ö 23.4 mm) (ZSI 5531 / 10), same data as lectotype. Other. Male (40.5 Ö 30.4 mm) (ZRC 1998.1145), Ban Krang, Huai Mae Phraeng, Kaeng Krachan National Park, Phetchaburi Province, Thailand, coll. T. Bundhitwongrut, 28 September 1998. Diagnosis Third maxilliped exopod with well-developed ¯ agellum, slightly longer than merus width. Male abdomen triangular; telson triangular, with distinctively concave lateral margins, tip rounded. G 1 terminal segment relatively long, c. 0.6 times length of subterminal segment, stout, c. 3.9 times longer than broad, twisted along longitudinal axis, with groove for G 2 clearly visible from ventral view, with distinct swelling on median part of inner margin, narrowed distal part straight, gently tapered, tip rounded with more or less ventral distal opening. G 2 distal segment c. 0.6 times length of basal segment. Remarks In the original description of this species, Alcock (1909) did not provide any other information about the material examined, except for the locality, which was stated only as`Hills between Burma and Siam’ (Alcock, 1909: 246). Alcock (1910) subsequently listed three lots of specimens in the Indian Museum under this species including one from the above-mentione d location consisting of an immature male and female specimen (ZSI 5531 / 10). These two specimens, which were examined, are the de facto syntypes of the species. The male specimen (27.4 Ö 21.2 mm) (ZSI 5531 / 10) is hereby designated as the lectotype of Stelomon pruinosum (Alcock, 1909). The remaining two lots of specimens mentioned by Alcock (1910), which were collected from`Tavoy’, are not types as they were not mentioned in the original publication and could not be located for examination in the ZSI. Another specimen from Tavoy, a juvenile male (NHM 1909.9.2.1), presented to the Natural History Museum, London, by the ZSI, was previously examined by the second author but this proved inconclusive as the G 1 was not fully developed (TuÈrkay and Naiyanetr, 1987: 391). It is a policy of the ZSI not to allow G 1 s of crab specimens to be detached for examination, therefore, we can only provide a photograph of the lectotype’s G 1 s in situ (® gures 3 C, D), while the present drawings and diagnosis of the G 1 of S. pruinosum are based on a non-type adult male specimen instead (® gures 5 B ± E). This specimen (40.5 Ö 30.4 mm) (ZRC 1998.1145) was recently collected from Kaeng Krachan National Park in Phetchaburi Province, Thailand, and matches the lectotype very well in external morphology and most aspects of the G 1 structure. The only diOEerence between the smaller lectotype and the non-type specimen is the G 1 being slightly more slender in the former (® gures 3 C, D, 5 B ± E). This is likely to be due to size-related variation and does not have any interspeci ® c signi ® cance. Bott (1970) synonymized Potamon pruinosum under Potamon (Potamon) rangoonensis Rathbun, 1904 (as a Ranguna), without explanation and without indicating whether he examined the types of either species. However, the specimen collected from Assam and deposited in the Forschungsinstitut Senckenberg (SMF 2807), which was ® gured by Bott (1970: pl. 38 ® gure 35, pl. 47 ® gure 31), is clearly not P. (P.) rangoonensi s sensu stricto. Bott’s specimen is not even congeneric with P. (P.) rangoonensis as its carapace is distinctly less rugose; the external orbital angle is broadly triangular (versus acutely triangular); and the G 1 is very diOEerent in form (cf. Rathbun, 1904: pl. 11 ® gure 2; TuÈrkay and Naiyanetr, 1987: 391, ® gures 1, 2). In any case, Bott’s (1970) synonymy was not valid, as Stelomon pruinosum can be immediately separated from both Bott’ s specimen as well as P. (P.) rangoonensis, by its more broadly triangular male abdomen (® gures 3 B, 5 H; cf. Bott, 1970: 1970: pl. 47 ® gure 31; Rathbun, 1904: ® gure 18) and very diOEerent G 1 structure (® gures 3 C, D, 5 B ± E; cf. Bott, 1970: pl. 38 ® gure 35; TuÈrkay and Naiyanetr, 1987: 391, ® gure 2). Externally, Stelomon pruinosum can be separated from S. kanchanaburiens e and S. tharnlod sp. nov. by its relatively broader triangular male abdomen (® gures 3 B, 5 H, 7 H; cf. Ng and Naiyanetr, 1993: ® gure 1 C). It is also easily separated from S. kanchanaburiens e by the distal part of its G 1 terminal segment being upright (versus distally hooked terminal segment) and the ventral facing G 1 distal opening (versus lateral facing distal opening) (® gures 2 B ± H, 5 B ± E). A less obvious diOEerence is seen in the ¯ agellum of the third maxilliped exopod of S. pruinosum, which is slightly longer than the merus width, while that of S. kanchanaburiens e never exceeds the merus width (® gures 2 A, 5 A). DiOEerences in the G 1 form between S. pruinosum and S. tharnlod are discussed under the Remarks for the latter species (see later). The G 1 terminal segment (especially the gently tapered distal part) of S. pruinosum resembles that ® gured by Bott (1970: pl. 39 ® gure 38) for Potamon (Potamon) turgidulimana Alcock, 1910, which may prove to be a fourth Stelomon species (see Remarks under genus). However, there are two other notable diOEerences in the G 1 subterminal segment of S. pruinosum (when viewed from all possible orientations) and the species ® gured by Bott (1970), namely: (i) the inner margin lacking a distal hump (versus the inner margin with a distinct distal hump present); and (ii) the outer margin distinctly sloping outwards and being gently convex (versus the outer margin not sloping outwards and being gently concave) (® gure 5 B; cf. Bott 1970: pl. 39 ® gure 38). In the live specimen, the dorsal carapace was very dark purple with whitish margins (frontal and anterolateral), cristae (epibranchial and postorbital) and rugae. The chelipeds were light purple with yellowish ® nger tips, and were covered with whitish granules and rugae. The ambulatory legs were light purple with slightly yellowish joints and bright yellow dactyli.	en	Yeo, D. C. J., Naiyanetr, P. (2000): A new genus of freshwater crab (Crustacea: Decapoda: Brachyura: Potamidae) from Thailand, with a description of a new species. Journal of Natural History 34 (8): 1625-1637, DOI: 10.1080/00222930050117521, URL: http://www.tandfonline.com/doi/abs/10.1080/00222930050117521
C010EF62FFC26835FA8AFD16FD44FC3E.taxon	materials_examined	Material examined HOLOTYPE: male (38.5 Ö 29.1 mm) (ZRC 1998.1146), Tritrung waterfall, Tharn Lod, Si Sawat District, Kanchanaburi Province, Thailand, coll. P. Naiyanetr, 8 September 1996. PARATYPE: male (c. 39.5 Ö 29.9 mmÐ broken carapace) (ZRC 1998.114 7), same data as holotype. Diagnosis Third maxilliped exopod with well-developed ¯ agellum, slightly longer than merus width. Male abdomen narrowly triangular; telson triangular, with distinctively concave lateral margins, tip rounded. G 1 terminal segment relatively long, c. 0.6 times length of subterminal segment, stout, c. 3.4 times longer than broad, twisted along longitudinal axis, with groove for G 2 clearly visible from ventral view, with distinct swelling on median part of inner margin, narrowed distal part straight, with distinct subdistal notch on outer margin, tip rounded, with more or less dorsal distal opening. G 2 distal segment c. 0.7 times length of basal segment. Remarks	en	Yeo, D. C. J., Naiyanetr, P. (2000): A new genus of freshwater crab (Crustacea: Decapoda: Brachyura: Potamidae) from Thailand, with a description of a new species. Journal of Natural History 34 (8): 1625-1637, DOI: 10.1080/00222930050117521, URL: http://www.tandfonline.com/doi/abs/10.1080/00222930050117521
C010EF62FFC26835FA8AFD16FD44FC3E.taxon	etymology	Etymology The species is named after its type locality, Tharn Lod in Kanchanabur i Province, Thailand. The name is used as noun in apposition.	en	Yeo, D. C. J., Naiyanetr, P. (2000): A new genus of freshwater crab (Crustacea: Decapoda: Brachyura: Potamidae) from Thailand, with a description of a new species. Journal of Natural History 34 (8): 1625-1637, DOI: 10.1080/00222930050117521, URL: http://www.tandfonline.com/doi/abs/10.1080/00222930050117521
