Sesarmops mora, Li & Shih & Ng, 2020

Li, Jheng-Jhang, Shih, Hsi-Te & Ng, Peter K. L., 2020, Paralbunea dayriti, Zoological Studies 59 (16), pp. 1-32 : 4-16

Bresedium brevipes (De Man, 1889) ( Figs. 1–6 )

Sesarma edwardsii – De Man 1887: 649; De Man 1888: 185 pl. 13 (1–4). (not Sesarma edwardsii De Man, 1888 ).

Sesarma edwardsii var. brevipes De Man, 1889: 425 (Sydney, Australia); De Man 1890: 94 (no locality); De Man 1892: 330 ( Flores).

Sesarma edwardsii var. breviceps (sic) – Bürger 1893: 617 ( Philippines).

Sesarma (Episesarma) edwardsi var. brevipes – De Man 1895: 173 (Atjeh, Sumatra, Indonesia).

Sesarma (Sesarma s. s.) edwardsi var. brevipes – De Man 1902: 509 ( Ternate, Batjan, Halmahera, Indonesia).

Sesarma (Sesarma s. s.) edwardsi philippinense Rathbun, 1914: 76 (Busuanga Island, Philippines); Tesch 1917: 148 (list).

Sesarma (Sesarma s. s.) edwardsii brevipes – Tesch 1917: 147 (Batjan, Indonesia).

Sesarma (Sesarma) brevipes – Serène 1968: 105 (list).

Sesarma (Sesarma) brevipes philippinensis – Serène 1968: 105 (list).

Bresedium brevipes – Serène and Soh 1970: 399 (taxonomy); Davie 2002: 220 (list); Ng et al. 2008: 220 (list); Koller et al. 2010: 366 (Taiwan); Li and Chiu 2013: 38, 3 unnumbered figs (Taiwan); Li and Chiu 2019a: 14, 2 unnumbered figs. (Taiwan); Li and Chiu 2019b: 58, 3 unnumbered figs (Taiwan).

Bresedium philippinensis – Serène and Soh 1970: 399 (discussion).

Bresedium philippinense – Ng et al. 2008: 220 (list).

Material examined: Holotype ( Sesarma (Sesarma) edwardsi philippinense Rathbun, 1914 ), male (16.7 × 14.5) ( USNM 45750 ), Pangauran R., Busuanga Island, Palawan, Philippines.

Others: Australia: 2 females (16.8 × 14.8, 15.3 × 13.3) ( RMNH D1210), “Australia, New South Wales, Sydney”, coll. Museum Godeffroy; 2 males (25.0 × 21.8, 24.0 × 21.3) ( ZRC 2009.0901), Flame Tree Creek, between Arlie Beach and Shute Harbour, Brisbane, Queensland, coll. J. W. Shaif and A. Humpherys, 2 June 1997. Philippines: Kawasan, Cebu: 8 males (18.4 × 15.5, 17.3 × 15.3, 15.9 × 13.4, 15.0 × 12.8, 15.7 × 13.8, 13.7 × 11.8, 13.5 × 11.7, 11.4 × 10.0), 2 females (21.1 × 17.7, 14.5 × 13.0) ( ASIZ 1125), coll. H.-C. Liu, 25 November 2001; 13 males (largest 24.7 × 21.0), 1 ovigerous female (19.7 × 16.8), 7 females ( ZRC 2019.1667), coll. P. K. L. Ng, 4 December 2001; 4 males (20.0 × 16.7, 18.4 × 15.7, 15.8 × 13.4, 12.6 × 11.2), 4 females (22.0 × 18.8, 16.3 × 13.8, 15.3 × 13.3, 10.9 × 9.2) ( ASIZ 1204), coll. H.-C. Liu, 4 December 2001; 5 males (25.7 × 21.9, 25.6 × 21.7, 24.4 × 21.3, 25.1 × 21.5, 22.6 × 19.3) ( ZRC 2016.0667), coll. N. K. Ng et al., 2 January 2002; 4 females (12.7 × 11.0, 11.2 × 9.3, 11.8 × 10.1, 9.8 × 8.4) ( ASIZ), coll. H.- C. Liu, 15 February 2003; Loboc R., Bohol: 3 males (16.4 × 14.0, 17.4 × 14.9, 18.9 × 15.7), 3 females (12.2 × 9.7, 15.6 × 13.4, 17.3 × 15.0), 2 ovigerous females (14.3 × 12.1, 17.9 × 17.6), NCHUZOOL 15555, coll. 26 September 2003. Taiwan: Gangkou R. estuary, Pingtung: 1 female (13.9 × 12.0) ( ZRC 2019.1644), coll. J.-J. Li, 13 July 2012; 1 female (16.9 × 14.3) ( ZRC 2019.1643), coll. J.-J. Li, 15 July 2012; 1 male (17.3 × 14.9), 1 female (16.3 × 13.3) (NCHUZOOL 16325), coll. J.-J. Li, 10 October 2014; 1 female (14.1 × 12.3)

( ZRC 2019.1645), coll. J.-J. Li, 24 September 2015; 1 female (14.9 × 12.7) ( ZRC 2019.1642), coll. J.-J. Li, 9 December 2015; 1 female (15.3 × 13.3) (NCHUZOOL 16320), coll. J.-J. Li, 20 June 2016; 1 female (20.0 × 16.8) (NCHUZOOL 16323), coll. J.-J. Li, 22 June 2016; 1 male (21.7 × 19.5) (NCHUZOOL 15549), 2 males (22.4 × 19.5, 22.0 × 19.0), 1 female (19.3 × 16.7) (NCHUZOOL 16324), 2 females (21.0 × 17.7, 19.6 × 16.5) (NCHUZOOL 16326), 1 male (21.1 × 17.8), 1 female (24.6 × 21.7) ( ZRC 2019.1641), coll. J.-J. Li, 18

May 2017; 2 males (22.3 × 18.9, 20.2 × 18.4), 1 female (20.5 × 17.8) (NCHUZOOL 16318), coll. J.-J. Li, 5 June 2017; 1 male (20.7 × 17.9), 1 female (21.0 × 18.3) (NCHUZOOL 16322), coll. J.-J. Li, 6 July 2017; 1 male (13.5 × 11.9) (NCHUZOOL 16321), coll. J.-J. Li, 7 July 2017; 1 male (18.8 × 16.3) (NCHUZOOL 16319), coll. J.-J. Li, 17 July 2017; 4 males (23.8 × 21.2, 20.9 × 18.7, 19.6 × 17.4, 19.4 × 17.3), 3 females (21.9 × 18.5, 17.4 × 14.8, 15.8 × 13.8) (NCHUZOOL 16327), 2 females (21.6 × 18.9, 16.3 × 14.0) ( ZRC 2019.1651), coll. J.-J. Li, 11 August 2017; 4 males (23.5 × 20.3, 21.9 × 19.6, 20.5 × 18.5, 17.3 × 15.2), 4 females (28.4 × 27.5, 27.2 × 26.9, 19.8 × 17.3, 17.7 × 15.1) (NCHUZOOL 16328), coll. J.-J. Li, 30 October 2017; 1 female (19.3 × 17.4) (NCHUZOOL 16317), coll. J.-J. Li, 20 April 2018; Gangzai R. estuary, Pingtung: 1 male (17.9 × 15.5) ( ZRC 2019.1646), coll. J.-J. Li, 16 June 2012; Meilun R. estuary, Hualien: 2 males (21.4 × 18.4, 13.7 × 12.2) ( ZRC 2008.0876), coll. H.-C. Liu, 2 December 2000; 1 female (14.7 × 13.2) ( ZRC 2019.1648), coll. J.-J. Li, 28 July 2012; 1 male (13.7 × 11.4) ( ZRC 2019.1649), 1 female (14.4 × 14.1) ( ZRC 2019.1647), coll. J.-J. Li, 3 March 2015; 1 male (15.4 × 13.7) ( ZRC 2019.1650), coll. J.-J. Li, 25 July 2015; 1 female (18.0 × 15.5) (NCHUZOOL 16329) coll. J.-J. Li, 3 August 2017. Indonesia: 1 male (22.2 × 19.1) ( RMNH D1195), Batjan Island, Moluccas, coll. Kükenthal Expedition, 1893–94; 1 male (5.8 × 5.1) (NCHUZOOL 15556), Bali, Indonesia, coll. H.- T. Shih, 22 July 2014.

Diagnosis of male: Carapace ( Figs. 2A, D , 4A, D, G ) square in dorsal view, 1.1 ± 0.1 times broader than long (n = 14); regions well defined, separated by shallow grooves; postfrontal region distinct, separated into 4 lobes by deep grooves; front deflexed downwards, margin distinctly concave in dorsal view. Anterolateral margin with large triangular, exorbital angle and smaller, triangular epibranchial tooth; lateral margin straight, slightly divergent posteriorly ( Fig. 4A ). Cornea reaching edge of external orbital tooth. Chelipeds ( Figs. 2F , 3G, H ) robust, outer surface with numerous rounded granules; dactylus dorsal margin with numerous chitinous granules; proximal part of fixed-finger slightly concave. Ambulatory legs ( Figs. 4B, E, H , 6A–D ) stout; P3 and P4 subequal, longer than others, about 1.4 ± 0.1 times carapace width (n = 14). P3 merus 2.2 ± 0.2 times as long as broad (n = 7); upper margin with acute subdistal spine. Propodus of P3 2.2 ± 0.2 times as long as broad (n = 7), with accessory stria on inferior proximal portion of outer surface, dorsal and ventral margins with short stiff setae. Dactylus of P3 0.6 ± 0.1 times length of propodus (n = 7), slightly curved, terminating in acute calcareous tip; dorsal and ventral margins with short stiff setae. Pleon ( Figs. 2B, C , 4C, F, I ) relatively broad, all somites free. Telson semicircular, evenly rounded, as long as preceding somite, base of telson deeply inserted in somite 6. G1 ( Figs. 5 , 6E–K ) straight, apical part chitinous, forming elongate slim process, bent at an angle of 35º–45º, ending in truncate tip.

Female: Carapace broader than male, 1.1 ± 0.03 times broader than long (n = 10). Chelipeds smaller than male, the base-half dactylus dorsal margin with numerous granules. Pleon wide, rounded, telson semicircular, base partially inserted in somite 6. Vulva ( Figs. 4J , 6L, M ) not near anterior edge of sternite 5, operculum knob-like; posterior sternal vulvar cover rounded, not covering operculum.

Colouration in life: There is considerable variation in colour, with the carapace brown to pale purple, usually with the gastric region dark brown; the chelae being reddish-orange to reddish-purple, with the tips of the fingers sometimes yellow ( Figs. 1 , 2 ).

Ecology: This species can be found both on land (several meters away from water) and the muddy river bank in habitats typically about 250 m to 500 m away from sea. It has been found sympatrically with more terrestrial sesarmids Geosesarma hednon Ng, Liu and Schubart, 2003 (Kenting, Pingtuing, Taiwan and Kawasan, Cebu, Philippines) and Sesarmops weberi (De Man, 1892) (Kawasan) . Along the river banks, it has been collected with Sesarmops mora n. sp. (Kenting and Kawasan) and Parasesarma dumacense ( Rathbun, 1914) (Kawasan) .

Remarks: De Man (1889) described Sesarma edwardsii var. brevipes from one male and two female specimens from Sydney, Australia. Measurements of one male (13.7 × 12.0 mm) and one female (13.8 × 12.3 mm) were provided. He also cited two of his earlier papers (De Man 1887 1888) where he described Sesarma edwardsii from Bengal seas and Mergui, but this was probably done with reference to the nominate species as he had regarded the Australian specimens as only a new variety. De Man (1890 1892 1895 1902) subsequently recorded this species from Sumatra, Flores and Moluccas. The real Sesarma edwardsii De Man, 1887 is a distinct species and is the type species of Pseudosesarma Serène and Soh, 1970 (see Ng and Schubart 2017). Noteworthy also is that in both B. brevipes (and B. philippinense ), the outer margins of the ambulatory carpus and propodus are densely lined with short black setae, absent in P. edwardsii s. str. (cf. Ng and Schubart 2017).

Rathbun (1914: 76) described Sesarma (Sesarma) edwardsi philippinense from three males and three females from Busuanga Island in the Philippines and noted that “Variety brevipes de Man has a male pleon similar to that of philippinense , but has much shorter legs. The legs of the Philippine form are as in typical edwardsi ” ( Rathbun 1914: 76). The holotype female of Bresedium philippinense ( Rathbun, 1914) is similar to specimens of B. brevipes in general morphology. Only minor diagnostic characters were provided in the original description by Rathbun (1914), who noted that the chelae of B. philippinense are narrower, the fingers are more elongate and more horizontal. Serène and Soh (1970: 399) commented that this taxon is probably a species of Bresedium and Ng et al. (2008) agreed.

De Man’s (1889) types of S. brevipes from “Sydney” are neither in the Senckenberg Museum or Naturalis (see Fransen et al. 1997). Davie (2002) commented that the types may be in the Amsterdam Museum. The Amsterdam Museum material has now been integrated with Naturalis collection (denoted still by its code of ZMA), but we have not been able to find these “Sydney” specimens there as well. In the Naturalis, however, there are two female specimens catalogued under RMNH D1210 from “ Australia, New South Wales, Sydney” which had been donated from the Museum Godeffroy. The data associated with these two specimens is: “ Topotype. Don. Museum Godeffroy, no. 16330 (error for 16300?). This material was described by De Man (1890: 94) under the above name, but was said to be from an unknown locality. Tesch (1917: 147–148) also referred to this lot and to De Man, 1890, noting that it was from an unknown locality. However, the sample has a handwritten number 16330. In Catalog viii of Museum Godeffroy ( Schmeltz 1881: 14, 15), it is listed on p. 14: “16300 Sesarma sp. ? Sidney”. This material is mentioned by De Man (1890), but he says the provenance of the specimen was not known, though he provided measurements for the larger female (16.8 × 14.8 mm). Interestingly, indications are that both these specimens are from Sydney in Australia as well, as clearly indicated by Schmeltz (1881: 14) in the above-mentioned catalogue of the Godeffroy Museum collections (see Bieler and Petit 2012, for details). Based on this information, these two female specimens cannot be the original syntypes of De Man (1889) (both female specimens are larger than his original female measured), and were only examined later. The original material of De Man (1889) therefore appears to be lost. Nevertheless, the RMNH specimens ( Fig. 3A ) and fresher ones from Brisbane ( Fig. 3B ) match the original descriptions and figures by De Man (1889) very well. The species is not known from further south in Sydney, which is probably too cold for the species in winter, and the original location is almost certainly incorrect ( Davie 2002: 220). The six type specimens of Bresedium philippinense ( Rathbun, 1914) are all in the USNM. Rathbun (1914) selected one male 16.7 mm in carapace length as the holotype, and this was examined for this study ( Fig. 3C, E, F ).

After comparing the good series of specimens from Australia (Brisbane), Indonesia ( Moluccas), Philippines (Kawasan, Cebu) and Taiwan (Hengchun Peninsula), supported by molecular evidence, we are confident Bresedium philippinense is a junior synonym of B. brevipes . There is significant variation in the proportion of the ambulatory legs, and other characters of the anterolateral margin and the angle of G1 tip ( Figs. 4A, D, G , 5 , 6E –K).

The third ambulatory leg of the specimens of B. brevipes from Australia and Indonesia agree in general with that illustrated by De Man (1889: pl. 9(6b)), especially in the width of the merus ( Fig. 4B ). On the other hand, the P3 merus of most of the present Philippine specimens are proportionately more slender and seem to agree better with the type and what was described by Rathbun (1914) for B. philippinense ( Fig. 4H ). Based on the measurement of 68 B. brevipes specimens (20 from the Philippines and 48 from Taiwan), the ratios of CW/P3 are 1.31–1.77 (average 1.56), in comparison, the ratios of CW/P3 are 1.49 in B. philippinense holotype, which is within the range (1.31–1.77) of CW/P 3 in B. brevipes . The leg (notably the width of the merus) is variable and therefore is not a reliable character to separate the species. The Taiwanese specimens in particular, have leg meri which vary from distinctly broad to more slender ( Figs. 4E , 6AC ). The G1 structures of the Australian, Indonesian and Taiwanese specimens differ from most of the Philippine specimens in that the elongated chitinous part is slightly more bent and the tip is usually bifurcated ( Fig. 5A– F ). Those of the Philippine specimens tend to have the chitinous part almost straight with the rest of the G1 and the tip is rounded ( Fig. 5G, H ). The specimens from the various sites, however, show that the variation is substantial and there are many intermediate states ( Figs. 5 , 6E–K ). As such, we do not believe the G1 differences observed are reliable. Comparing some of the larger specimens, we also find that the carapace of those from the Philippines is usually more setose, being uniformly covered with numerous tufts of short setae (vs. scattered short setae mainly on anterior surface in specimens from Australia and occasionally Taiwan); the ambulatory dactylus has slightly more short setae ( Fig. 2D vs. Figs. 2A , 3 A-C); the median part of the male pleon has a pair of short, black stiff setae, with the margins of the telson having more of the same kind of setae (vs. may be indistinct) ( Fig. 4C, F vs. Fig. 4I ). That being said, when specimens of various sizes are compared, these characters vary enough to make them unreliable. As a result, we believe both species are synonymous. This is also supported by the available genetic data ( Fig. 22 ).

Bresedium eurypleon n. sp. ( Figs. 7–10 ) urn:lsid:zoobank.org:act:830368D5-74B1-4B1F-8436-F5ABF22F0063

Bresedium philippinensis – Liu 2016: 7, 20, 24, 33, 65, fig. 3-1.1 (Pingtung, Taiwan). (not Sesarma (Sesarma) edwardsi philippinense Rathbun, 1914 )

Material examined: Holotype: male (17.9 × 14.8) (NCHUZOOL 16316), Houwan forest , Pingtung, Taiwan, coll. J.-J. Li, 8 May 2019 . Paratypes: Taiwan: 1 female (19.6 × 16.7) (NCHUZOOL 16379), 1 ovigerous female (19.9 × 17.1) (larvae released) (NCHUZOOL 16331), Houwan beach, Pingtung, coll. H.-D. Yang, 15 August 2015; 1 female (18.9 × 15.8) ( ZRC 2019.1652), Gangkou R. estuary, Pingtung; 1 female (15.6 × 13.4), NCHUZOOL 15557, Houwan, Pingtung, coll. M.-Z. Wu and C.-Y. Chi, 1 October 2016; 1 female (20.5 × 17.6) (NCHUZOOL 15558), Houwan, Pingtung, P.- Y. Hsu et al., 21 July 2017; 1 female (18.8 × 15.0) (NCHUZOOL 16316), Nioushan, Hualien, coll. P.-H. Ho, 12 June 2016. Others: Philippines: 1 male (20.9 × 19.2) ( ZRC 2017.0478a), 3 males (19.6 × 16.1, 17.6 × 14.4, 17.5 × 14.4) ( ZRC 2017.0478b), Jordan, Guimaras Island, coll. J. C. E. Mendoza, 1 June 2017. Indonesia: 1 male (26.2 × 22.7) ( ZRC 2019.1660), Manado Murex Resort, North Sulawesi, coll. P. K. L. Ng et al., 17 July 2013.

Comparative material: Bresedium sediliense ( Tweedie, 1940) : Malaysia: Johor: 37 males (largest 21.2 × 18.2 mm), 22 females (largest 20.3 × 17.8 mm) ( ZRC 1965.7.29.121–133) [paratypes of Sesarma sediliensis Tweedie, 1940 ], Sedili River, coll. M. W. F. Tweedie, March 1938. Sarawak: 19 males (largest 20.1 × 17.9 mm), 17 females (largest 19.2 × 16.7 mm, 2 ovigerous) ( ZRC 1972.3.7.25–35), water ditch, Kuching, coll. M. W. F. Tweedie, January 1949.

Diagnosis of male: Carapace ( Figs. 7A, F , 8A , 10A ) almost rectangular in dorsal view, 1.2 ± 2.0 times broader than long (n = 5); regions well defined, separated by shallow grooves; postfrontal region distinct, separated into 4 lobes by deep grooves; front deflexed downwards, margin distinctly concave in dorsal view. Anterolateral margin with large triangular, exorbital angle and smaller, triangular epibranchial tooth; lateral margin straight, slightly divergent posteriorly. Cornea reaching edge of external orbital tooth. Chelipeds ( Figs. 7C, H , 8C, D ) robust, outer surface with numerous rounded granules; dactylus dorsal margin with numerous chitinous granules; proximal part of fixed-finger slightly concave. Ambulatory legs ( Figs. 7A , 8A ) stout; P3 and P4 subequal, longer than others, about 2.1 ± 0.1 times carapace width (n = 5). P3 merus 2.0 ± 0.1 times as long as broad (n = 5); upper margin with acute subdistal spine. Propodus of P3 2.5 ± 0.1 times as long as broad (n = 5), with accessory stria on inferior proximal portion of outer surface, dorsal and ventral margins with short stiff setae. Dactylus of P3 0.9 ± 0.1 times length of propodus (n = 5), slightly curved, terminating in acute calcareous tip; dorsal and ventral margins with short stiff setae. Pleon ( Figs. 7B , 8B ) relatively broad, all somites free. Telson semicircular, evenly rounded, as long as preceding somite, base of telson deeply inserted in somite 6. G1 ( Figs. 8G, H , 10B, C ) straight, apical part chitinous, forming elongate slim process, bent at an angle of about 55º, ending in truncate tip.

Female: Carapace ( Figs. 7D , 9 ) broader than male, 1.2 ± 0.6 times broader than long (n = 3). Chelipeds smaller than male, the base-half dactylus dorsal margin with numerous granules. Pleon wide, rounded, telson semicircular, base partially inserted in somite 6. Vulva ( Figs. 8F , 10D ) near anterior edge of sternite 5, operculum knob-like; posterior sternal vulvar cover triangular, elongate, covering operculum in ventral view.

Etymology: The name is derived from the Greek “eury” and “pleon” for wide and male pleon, respectively; alluding to the proportionately wider structure of the species. The name is used as a noun.

Colouration in life: Carapace and legs brown, with or without some speckles; chelipeds evenly reddish purple ( Fig. 7 ).

Distribution: Taiwan (Hualien and Pingtung), Philippines (Guimaras Island) and Indonesia (Sulawesi).

Ecology: Three females were found to release larvae into the sea during high tide of full moon night in August 2015 ( Liu 2016; JJ Li, personal observation). Another non-ovigerous female was found on a muddy bank of the lower reaches of a small stream river in Niousha, Hualien, Taiwan.

Remarks: Male B. eurypleon n. sp. can easily be distinguished from adult male B. brevipes by its relatively broader and more trapezoidal-shaped carapace ( Figs. 7A, D, F , 8A , 9 ) (narrower, squareshaped carapace in B. brevipes ; Figs. 2A, D , 3A–C ); the relatively smaller granules on the outer surface of the palm ( Fig. 8C, E ) (relatively larger in B. brevipes ; Figs. 2F , 3G ); distinctly wider male sixth pleonal somite ( Fig. 7B ) (proportionately narrower in B. brevipes ; Figs. 2B, C , 3D, F ); and the relatively more elongated and bent male G1 tip ( Fig. 8G, H ) (shorter and almost in line with the stem in B. brevipes ; Figs. 5 , 6E–K ). The vulvae are different in the two species, with the posterior sternal vulvar cover triangular and more elongate, covering the operculum in B. eurypleon ( Figs. 8F , 10D ) whereas in B. brevipes , the posterior sternal vulvar cover is rounded and the operculum is clearly exposed ( Figs. 4J , 6L, M ).

The carapace shape slightly varies in females, with one specimen from southern Taiwan being more broadly trapezoidal ( ZRC 2019.1652) ( Fig. 9A ) compared to those from other parts of the island ( Fig. 9B, C ). This is regarded as intraspecific variation and supported by the genetic data ( Fig. 22 ).

In life, adults of both species show similar colouration of carapace and legs, with large males of B. brevipes often possessing purple palms with finger tips yellow ( Fig. 2B, F ), with medium-sized and small males with light brownish red palms and orange fingers ( Fig. 2C ). Some specimens, however, have the entire chela purple ( Fig. 2F ). All specimens of B. eurypleon examined, however, always have purple palms and fingers, with the tip pale but not distinctly yellow ( Fig. 7C, H ).

Figures

Fig. 1. Bresedium brevipes (De Man, 1889), in situ photographs in Taiwan. A, male (specimen not collected), Gangkou R. downstream, south bank, Pingtung, 13 January 2011; B, female (18.0 × 15.5 mm) (NCHUZOOL 16329), Gangkou R. downstream, south bank, Pingtung; C, male (17.9 × 15.5 mm) (ZRC 2019.1646), Gangzai R. estuary north bank, Pingtung; D, female (specimen not collected), Gangkou R. estuary, north bank, Pingtung, 4 July 2011; E, male (specimen not collected), Gangkou R. estuary, north bank, Pingtung, 13 July 2014; F, female (specimen not collected), Gangkou R. downstream, south bank, Pingtung, 13 January 2011.

Fig. 2. Bresedium brevipes (De Man, 1889), life colouration. A, B, male (20.5 × 17.8 mm) (NCHUZOOL 16318), Gangkou R., Taiwan; C, male (17.9 × 15.5 mm) (ZRC 2019.1646), Gangzai R., Taiwan; D–F, male (25.1 × 21.5 mm) (ZRC 2016.0667), Kawasan, Cebu, Philippines.A, D, overall dorsal view; B, C, ventral view of cephalothorax; E, frontal view of cephalothorax; F, outer view of left chela.

Fig. 3. Bresedium brevipes (De Man, 1889). A, female (15.3 × 13.3 mm) (RMNH D1210), “Sydney”, Australia; B, D, male (25.0 × 21.8 mm, 24.0 × 21.3 mm) (ZRC 2009.0901), Brisbane, Australia; C, E, F, male (16.7 × 14.5 mm) (USNM 45750) (holotype of Sesarma (Sesarma) edwardsi philippinense Rathbun, 1914), Philippines; G, H, male (17.9 × 15.5 mm) (ZRC 2019.1646), Gangzai R., Taiwan; I, female (14.1 × 12.3 mm) (ZRC 2019.1645), Gangzai R., Taiwan.A–C, overall dorsal view; E, dorsal view of carapace; D, F, ventral view of anterior thoracic sternum and pleon; G, I, outer view of left chela; H, dorsal view of left chela.

Fig. 4. Bresedium brevipes (De Man, 1889). A–C, male (22.2 × 19.1 mm) (RMNH D1195), Batjan Island, Indonesia; D–F, male (21.3 × 18.5 mm) (ZRC 2019.1667), Taiwan; G–I, male (24.7 × 21.0 mm) (ZRC), Philippines. A, D, G, right side of carapace; B, E, H, left third ambulatory leg; C, male pleonal somites 3–6 and telon; D, E, male pleonal somites 5, 6 and telson. Scale bars = 1.0 mm.

Fig. 5. Bresedium brevipes (De Man, 1889). A–D, male (22.2 × 19.1 mm) (RMNH D1195), Batjan Island, Indonesia, right G1; E, F, male (21.3 × 18.5 mm) (ZRC), Taiwan, left G1; G, H, male (24.7 × 21.0 mm) (ZRC), Philippines, left G1. A, F, H, dorsal view; B, E, G, ventral view; C, D, distal part of G1. Scale bars = 1.0 mm.

Fig. 6. Bresedium brevipes (De Man, 1889). A–C, B. brevipes; D, Sesarma (Sesarma) edwardsi philippinense, holotype. A, male (22.0 × 19.0 mm) (NCHUZOOL 16324), Taiwan; B, male (22.3 × 18.9 mm) (NCHUZOOL 16318), Taiwan; C, male (19.3 × 17.4 mm) (NCHUZOOL 16319), Taiwan; D, male (16.7 × 14.5 mm) (USNM 45750) (holotype of Sesarma (Sesarma) edwardsi philippinense Rathbun, 1914), Philippines; E, male (20.7 × 17.9) (NCHUZOOL 16322), Taiwan; F–J, males 25.6 × 21.7 mm, 22.6 × 19.3 mm, 25.7 × 21.9 mm, 24.4 × 21.3 mm, 25.1 × 21.5 mm) (ZRC 2016.0667), respectively, Philippines; K, male (24.9 × 21.8) (ZRC 2009.0901), Australia; L, female (16.9 × 14.3 mm) (ZRC 2019.1643), Taiwan; M, ovigerous female (19.7 × 16.8 mm) (ZRC 2019.1667), Philippines. A–D, right side of carapace and P3; E–K, left G1s; L, M, vulvae.

Fig. 22. Bayesian inference (BI) tree for species of Sesarmidae, based on combined 16S rDNA and cytochrome c oxidase subunit I (COI) genes. Probability values at nodes represent support values for BI and maximum likelihood (ML). For haplotype names, see table 1.

Fig. 7. Bresedium eurypleon n. sp., colour in life. A–C, holotype male (17.9 × 14.8 mm) (NCHUZOOL 16316), Taiwan; D, paratype female (18.9 × 15.8 mm) (ZRC 2019.1652), Taiwan; E–H, male (26.2 × 22.7 mm) (ZRC 2019.1660), Sulawesi. A, D, E, F, overall dorsal view; B, ventral view of cephalothorax; C, outer view of chelae; G, frontal view of cephalothorax; H, outer view of left chela.

Fig. 8. Bresedium eurypleon n. sp. A, B, male (20.9 × 19.2 mm) (ZRC 2017.0478a), Philippines; C, D, G, H, Taiwan, holotype male (17.9 × 14.8 mm) (NCHUZOOL 16316), Taiwan; E, F, paratype female (18.9 × 15.8 mm) (ZRC 2019.1652), Taiwan. A, dorsal view; B, ventral view; C–E, left palms; F, vulvae; G, H, left G1.

Fig. 9. Bresedium eurypleon n. sp., dorsal view of carapace. A, paratype female (18.9 × 15.8 mm) (ZRC 2019.1652), Kangkou River, Taiwan; B, paratype female (20.6 × 16.6 mm) (NCHUZOOL 16331), Houwan, Pingtung, Taiwan; C, paratype female (18.8 × 15.0 mm) (NCHUZOOL 16316), Nioushan, Hualien, Taiwan.

Fig. 10. Bresedium eurypleon n. sp.A–C, male (20.9 × 19.2 mm) (ZRC 2017.0478a), Philippines; D, paratype female (18.8 × 15.0 mm) (NCHUZOOL 16316), Taiwan. A, left side of carapace; B, left G1; C, distal part of lef G1; D, left female vulva. Scale bars = 1.0 mm.