Parasesarma De Man, 1895

Shih, Hsi-Te, Hsu, Jhih-Wei & Li, Jheng-Jhang, 2023, Fig. 34. Lacunipotamon mimicum n in Fig. 20 in Lanternflies (Hemiptera: Fulgoridae) of Taiwan., Zoological Studies 62 (34), pp. 1-38 : 7-27

Genus Parasesarma De Man, 1895 Parasesarma bidens (De Haan, 1835) ( Figs. 2 , 3 , 7C–E , 9A, B , 10C , 11C , 12A )

Grapsus (Pachysoma) bidens De Haan 1835: 60 , pls. 11(4), 16(4) [type locality: Japan].

Sesarma bidens – H. Milne Edwards 1853: 185 ( Japan); Stimpson 1858: 105 ( Japan); Stimpson 1907: 134 (part; only Japan); Ortmann 1894: 726 (part; only Japan).

Sesarma (Perisesarma) bidens – Yamaguchi and Baba 1993: 484, fig. 184 [lectotype] ( Japan).

Sesarma (Chiromantes) bidens – Tesch 1917: 132 [syntypes] ( Japan); Urita 1926: 20 (Kyushu, Japan); Sakai 1934: 325 (Kyushu, Japan); Sakai 1936: 236, pl. 66(1) ( Japan); Sakai 1939: 688, pl. 79(1) (part; only main islands of Japan); Sakai 1940: 42 ( Japan); Kamita 1941a; 226, text-fig. 125 (Jeju, Korea); Kamita 1941b: 236, 242 (Jeju, Korea); Miyake 1963: 68 (Iriomote, Japan); Sakai 1965: 203 (Japanese part: p. 90), pl. 98(1) (Sagami Bay, Japan); Nishimura and Suzuki 1971: 125, pl. 46(4) ( Japan); HS Kim 1973: 655 (Jeju, Korea); Sakai 1976: 658, pl. 225(1) (main islands of Japan); HS Kim and Chang 1985: 56 (Jeju, Korea); Nagai and Nomura 1988: 46, 1 unnumbered fig. (Okinawa, Japan); Muraoka 1998: 54 (part; only Japan).

Chiromantes bidens – Fukuda and Baba 1976: 62, figs. 1–4, 5a–c, 6–8 (Kyushu, Japan); Takeda 1982: 221, 1 unnumbered fig. (south of Tokyo Bay, Japan).

Perisesarma bidens – Miyake 1983: 182, pl. 61(3) (Tokyo Bay– Kyushu; Okinawa, Japan); Hirata et al. 1988: 26, 1 unnumbered fig. (Okinawa, Japan); Islam and Shokita 2000: 44, figs. 1–5 (Okinawa, Japan); Islam et al. 2000: 153 (Okinawa, Japan); Suzuki 2002: 334, 2 unnumbered figs. (Amami, Japan); Nakasone and Irei 2003: 272 (Okinawa, Japan); Komai et al. 2004: 48, fig. 7B, D (Kumejima and Iriomote, Japan); Takeda et al. 2006: 207 (Sagami Bay, Japan); Ng et al. 2008: 222 (part); Era and Kishi 2009: 39, 1 unnumbered fig. ( Japan); Fujita et al. 2009: 43 (Amami, Japan); Mchenga and Tsuchiya 2010: 201932 (p. 2) (Okinawa, Japan); Poon et al. 2010: 30 ( HK); Ko and SH Lee 2012: 22, pl. 5B (Jeju, Korea); Miura 2012: 60 (Amami, Japan); Watanabe 2014: 80, 3 unnumbered figs. ( Japan); Kawaida et al. 2017: 1009 (Iriomote, Japan); Maenosono 2015: 19 (Iriomote, Japan); Maenosono and Naruse 2015: 7 (Okinawa, Japan); Maenosono and Saeki 2016: 8, fig. 3C (Ishigaki, Japan); Inui et al. 2019: 45 (Sagami Bay, Japan); SK Lee et al. 2021: S13 ( Korea).

Parasesarma bidens – Shahdadi and Schubart 2017: 520 ( Japan incl. Ryukyus); Ishida and Maenosono 2019: 5 (Miyako, Japan); JJ Li et al. 2019: 40 (p. 2) (part; only Japan incl. Ryukyus); Sasaki 2019: 13068 (part); Toyota et al. 2019: 254, 5 unnumbered figs. (Okinawa, Japan); SY Kim et al. 2020: 160, fig. 2 (Jeju, Korea); Shahdadi et al. 2020a: 1125 ( Japan incl. Ryukyus); Shahdadi et al. 2020b: 399 (part; only Japan); Shahdadi et al. 2022: e0262122 (p. 3), S1 table (part; only Japan incl. Ryukyus; Korea).

Material examined: Lectotype ò, RMNH 145 , paralectotype ñ RMNH 144 , paralectotype ñ (CW 30.1 mm), RMNM, Japan (photographs examined; Fig. 2 ). Others: Japan: 2 òò (22.0 × 18.7, 19.2 × 15.7 mm), 2 ññ (26.8 × 22.6, 20.4 × 17.8 mm), NCHUZOOL 15511, Arifukucho , Nagasaki, coll. Y. Nakahara, 23 Sep. 2018; 5 òò (31.6 × 25.6, 29.5 × 23.6, 28.9 × 23.0, 27.9 × 22.1, 21.9 × 17.8 mm), NCHUZOOL 15635, Kyushu, coll. T. Naruse et al., 3 Oct. 2017; 2 òò (29.4 × 24.9, 18.1 × 14.9 mm), NCHUZOOL 15634, Okinawa, Ryukyus, coll. J.-J. Li, 18 Jul. 2016; 8 òò (27.9 × 23.7, 24.4 × 20.6, 21.0 × 18.0, 18.8 × 16.1, 16.1 × 13.6, 16.0 × 13.7, 13.3 × 11.1, 13.1 × 10.8 mm), NCHUZOOL 17115, Okinawa, Ryukyus, coll. J.-J. Li, 19 Jul. 2016; 1 ò (11.4 × 9.0 mm), NCHUZOOL 15506, Okinawa, Ryukyus, coll. K. Wong, 9 Jul. 2009; 1 ò (23.3 × 19.6 mm), NCHUZOOL 15510, Miyako, Ryukyus coll. H.- T. Shih, 11 Apr. 2002; 1 ò (27.7 × 23.8 mm), NCHUZOOL 15709, Iriomote, Ryukyus, coll. P.-C. Tsai, 8 Jul. 2011; 1 ò (7.9–19.8 × 7.9–19.8 mm), NCHUZOOL 15509, Iriomote, Ryukyus, 8 Jul. 2011.

Diagnosis: Carapace ( Fig. 3A, E ) subrectangular, 1.21–1.28 times broader than long (N = 7), body relatively slightly vaulted; front moderately downwards and sloping forward, deflexed part of front relatively shorter in frontal view ( Figs. 3C , 9A ). Postfrontal separated into 4 lobes, longitudinally narrower, higher in frontal view; median lobes prominent, lateral lobes very distinct in frontal view. Anterolateral margin with 1 tooth behind external orbital tooth, lateral margin of external orbital tooth relatively straight. Chelipeds homochelous, large, robust; palm with 2 transverse pectinate crests on upper surface ( Fig. 3A ), secondary crest often absent in female; distal (primary) crest composed of 10–19 tall, broad corneous teeth; secondary crest well developed, with 4–14 corneous teeth. Dorsal surface of chelar dactylus with 11–18 distinct, slightly transversely broadened tubercles, proximal 1 or 2 tubercle(s) smallest but distinct, tubercles without ringed grooves on dorsal surface; 1 row of ca. 11–17 small rounded tubercles on proximal part of inner edge of dorsal surface ( Figs. 3F , 10C ). Male pleon ( Fig. 3B, G ) triangular. G1 ( Fig. 3H–K ) relatively stout, straight; apical process short, corneous part ( Figs. 3I, J , 11C ) shorter, bent at angle of ca. 60° to vertical axis (N = 3), ending in rounded tip. Vulva ( Figs. 3M , 12A ) with slightly elongated semicircular sternal vulvar cover; sunken on mesial part.

Description: Carapace ( Fig. 3A, E ) subrectangular in dorsal view, 1.21–1.28 times broader than long (N = 7), greatest width often between external orbital teeth, body relatively slightly vaulted; surface smooth, punctated, with numerous short, transverse to slightly oblique crests edged with rows of short setae, sometimes forming low tufts. Dorsal carapace regions moderately well indicated; gastric region demarcated; cardiac region separated from intestinal region. Front ca. 0.58–0.60 times carapace width (N = 6), moderately downwards, sloping forwards, margin slightly concave medially in dorsal view; deflexed part of front relatively shorter in frontal view. Postfrontal well delimited, separated into 4 lobes by deep furrow; median lobes prominent, slightly broader than lateral ones; lateral lobes prominent, very convex, distinct in frontal view; lobes longitudinally narrower, higher in frontal view ( Figs. 3C, E , 9A, B ). Anterolateral margin not granulated, with 1 tooth behind external orbital tooth, external orbital tooth triangular, directed obliquely outwards, lateral margin of external orbital tooth often relatively straight; lateral margins straight, with 1 row of short setae, slightly converging posteriorly. Third maxilliped with ischium bearing shallow median sulcus; merus with distinct submedian ridge; exopod slender, flagellum long. Cornea slightly wider than eyestalk.

Chelipeds ( Fig. 3A, D ) homochelous, large, robust (length ca. 1.72 × width). Merus with granulate dorsal border and distinct subdistal spine; anterior border granulated, with distinct subdistal spine; inner face smooth with 2 longitudinal rows of setae, ventral row more prominent, continuous, with longer setae, dorsal row interrupted. Carpus with inner angle not produced; inner margin granular; outer surface striated, granular. Palm ( Fig. 3A ) with 2 transverse pectinate crests on upper surface, secondary crest often absent in female; distal (primary) crest composed of 10–19 tall, broad corneous teeth; secondary crest well developed, with 4–14 corneous teeth; 1 or 2 row(s) of coarse granules (some with chitinous cap) proximal to second crest. Outer surface of palm without setae, lacking any indication of median longitudinal ridge ( Fig. 3D ); inner surface of palm with numerous granules, without setae; ventral border of chela almost straight. Dactylus almost straight, stout, ca. 0.62 times propodus length; fingers each with chitinous tip, with or without narrow gape when fingers closed, cutting edge of both fingers with series of variably sized teeth ( Fig. 3D ). Dorsal surface of chelar dactylus with 11–18 distinct, slightly transversely broadened tubercles, proximal 1 or 2 tubercles smallest but distinct, tubercles without ringed grooves on dorsal surface; 1 row of ca. 11–17 smaller rounded tubercles on proximal two-thirds of inner edge of dorsal surface ( Figs. 3F , 10C ).

Ambulatory legs ( Fig. 3A ) slender, laterally flattened; P3 and P4 subequal, longer than others. Merus of P3 2 times as long as broad; upper margin with acute subdistal spine. Meri of P2–P5 with transverse striae on upper surface. Carpus of P2–P5 with 2 carinae on outer surface. Propodus of P3 ca. 2.7 times as long as broad, with striae on outer surface, margins with short stiff setae. Dactylus of P3 ca. 0.7 times length of propodus, slightly curved distally, terminating in acute tip; margins with short stiff setae.

Male pleon ( Fig. 3B, G ) triangular, with telson length equal to basal width; somite 6 longer than others, almost twice as long as wide, lateral margins slightly convex; somite 3–5 more trapezoidal, lateral margins of somites 4 and 5 almost straight, lateral margins of somite 3 strongly convex. G1 ( Fig. 3H–K ) relatively stout, straight; stem triangular with blunt angles in cross section; apical process short, corneous part shorter, bent at angle of ca. 60° to vertical axis (N = 3), ending in rounded tip ( Figs. 3I, J , 11C ); setae long, simple, originating at base of apical process. G2 shorter than quarter length of G1. Vulva ( Figs. 3M , 12A ) in depression on anterior edge of sternite 5, with slightly elongated semicircular sternal vulvar cover; sunken on mesial part.

Size: Largest male CW 31.6 mm (NCHUZOOL 15635); largest female CW 26.8 mm (NCHUZOOL 15511).

Color in life: Usually carapace and legs brown, mixed with pale and dark brown patches; palm pale brown or orange; fingers darker ( Fig. 7C–E ; Table 3).

Distribution: Japan (including the Ryukyus) and South Korea (Jeju Island) ( Fig. 1 ).

Remarks: The detailed type locality of Parasesarma bidens was not provided in De Haan (1835). Given that De Haan’s specimens of P. bidens deposited in Leiden were collected by Siebold and Burger ( Fig. 2 ; Yamaguchi and Baba 1993), and it is believed that the materials of the two collectors were obtained near Nagasaki ( George and Holthuis 1965), it is reasonable to restrict the type locality of P. bidens to the area surrounding Nagasaki.

Parasesarma bidens is morphologically similar to the other three new species in the P. bidens species complex but can be distinguished more reliably by the characters of the frontal and postfrontal regions of the carapace in both sexes, as well as the G1s ( Table 3). However, the vulval characters, including the angle and the aspect ratio of operculum, are too variable to be used in distinguishing the four species. This species is very similar to P. insulare in the shorter deflexed part of the frontal region (vs. longer in other two species), as well as the short apical process and shorter corneous part of G1s (vs. longest in P. continentale and longer in P. chiahsiang ). However, the lateral lobes (especially the lateral part) of the postfrontal region are particularly distinct (in frontal view) in P. bidens ( Figs. 3C , 9A ) [vs. lateral lobes (especially the lateral part) of the postfrontal region indistinct in P. insulare ( Figs. 5C , 9E )].

Among the six species of the P. bidens species complex, P. cricotum and P. sanguimanus are characterized by the ringed grooves on the surface of tubercles of the chelar dactylus ( Fig. 10A–B ) ( Rahayu and Davie 2002; JJ Li et al. 2019), with more rounded tubercles in the former (JJ Li et al. 2019: fig. 8E) and relatively ovate in the latter (JJ Li et al. 2019: fig. 8B). Therefore, the comparison of the chelar dactylus between the two species in the Remarks under P. sanguimanus (JJ Li et al. 2019) needs to be amended.

Parasesarma continentale n. sp. ( Figs. 4 , 7F–H , 9C, D , 10D , 11D , 12B ) urn:lsid:zoobank.org:act:2F03D495-424B-4FC5-A804-C586EB84BEAC

Sesarma bidens – Heller 1865: 64 (part; only Hong Kong); Bürger 1893: 628 (part; only Hong Kong); Stimpson 1907: 134 (part; only Japan); YQ Xu and You 1987: 92 (Fujian, China); Do and Hoang 2002: 128 (N Vietnam); Do and Hoang 2004: 14 (N Vietnam); Do and Hoang 2006: 36 (N Vietnam); W Li et al. 2010: 2930 (Fujian, China). (not Sesarma bidens De Haan, 1835 ).

Sesarma (Chiromantes) bidens – CJ Shen 1936: 69 (Hainan, China); CJ Shen 1940a: 74 (South China); CJ Shen 1940b: 237 ( Hong Kong); CJ Shen and JY Liu 1963: 141 ( China); CJ Shen and Dai 1964: 137, 1 unnumbered fig. ( China); Dai and Song 1977: 363 ( China); Gao and Li 1985: 183 (Fujian, China); Dai and Song 1986: 60 (Guangxi, China); Dai et al. 1986: 491, fig. 276(3), pl. 69(4) ( China); Dai and Yang 1991: 538, fig. 276(3), pl. 69(4) ( China); QQ Wu et al. 1992: 164 (Guangdong, China); ZG Huang 1994: 597 ( China); Lu 1996: 167 (Xiamen, Fujian, China); Tam and Wong 2000a: 58, 2 unnumbered figs. ( Hong Kong); Tam and Wong 2000b: 115, 2 unnumbered figs. ( Hong Kong); ZG Huang 2008: 667 ( China). (not Sesarma bidens De Haan, 1835 ).

Chiromantes bidens – Soh 1978: 10, pl. 2a ( Hong Kong); Kwok and SY Lee 1995: 142 ( Hong Kong). (not Sesarma bidens De Haan, 1835 ).

Perisesarma bidens – Wang and Liu 1996c: 226 (Kinmen, Taiwan); Kosuge et al. 1997: 182 (N Vietnam); Ng et al. 2001: 53 (Kinmen, Taiwan); SY Lee and Kwok 2002: 216 ( Hong Kong); CH Wang 2003: 108, 1 unnumbered fig. (Kinmen, Taiwan); Fong et al. 2005: 61, 4 unnumbered figs. ( Hong Kong); Kwok and Tang 2005: 3, fig. 13 ( Hong Kong); So and Lui 2007: 34, 3 unnumbered figs. ( Hong Kong); Yang et al. 2008: 802 ( China); Hoang et al. 2010: 155 (N Vietnam); JR Huang et al. 2011: 732 (Guangdong, China); Yang et al. 2014: 349 (Guangxi, China); Zhou et al. 2016: 3256 ( China); Y Xu et al. 2019: 64 ( China); YT Li et al. 2020: 536640 (p. 2) (Fujian, China); Hoang et al. 2021: 116 (N Vietnam). (not Sesarma bidens De Haan, 1835 ).

Sesarma (Perisesarma) bidens – SY Lee and Leung 1999: 64, pl. 5 ( HK). (not Sesarma bidens De Haan, 1835 ).

? Sesarma bidens – Do 2003: 7 (S Vietnam). (not Sesarma bidens De Haan, 1835 ).

Parasesarma bidens – LP Wang 2005: 179 (Kinmen, Taiwan); LP Wang 2009: 238 (Kinmen, Taiwan); Ng et al. 2017: 132 (Kinmen, Taiwan); Sasaki 2019: 13068 (part); Shahdadi et al. 2022: e0262122 (p. 3), S1 table (part; only China (Hainan and Hong Kong) ( China); Nguyen et al. 2022: 38 (Dong Rui, N Vietnam). (not Sesarma bidens De Haan, 1835 ).

? Perisesarma bidens – Chertoprud et al. 2012: 280 (S Vietnam); Hoang et al. 2012: 75 (S Vietnam). (not Sesarma bidens De Haan, 1835 ).

Parasesarma affine – CC Hung 2017: 174, 2 unnumbered figs. (Kinmen, Taiwan). (not Parasesarma affine (De Haan, 1837)) (not Sesarma affine De Haan, 1837 ).

Material examined: Holotype: 1 ò (18.5 × 15.5 mm), NCHUZOOL 17065, Lieyu, Kinmen, Taiwan, coll. H.- T. Shih and P.-Y. Hsu, 28 Jun. 2018 . Paratypes: 1 ò (22.7 × 18.9 mm), NCHUZOOL 17069, Wujiang R. estuary, Kinmen, coll. J.-J. Li, 1 Jul. 2017; 10 òò (17.3 × 14.2–12.7 × 10.0 mm), NCHUZOOL 15638, 1 ñ (14.7 × 11.9 mm), ZRC 2023.0197, Yingshan Temple, Jinsha, Kinmen, coll. J.-J. Li, 2 Jul. 2017; 1 ò (17.2 × 14.3 mm), 1 ovig. ñ (11.3 × 8.8 mm), NCHUZOOL 17070, Yingshan Temple, Jinsha, Kinmen, coll. J.-J. Li, 2 Jul. 2017; 1 ñ (18.7 × 15.6 mm), NCHUZOOL 17066, Cingyuan Lake, Lieyu, Kinmen, coll. H.- T. Shih and P.-Y. Hsu, 28 Jun. 2018; 1 ò (18.9 × 15.6 mm), ZRC 2023.0196, Wujiang R. estuary, Kinmen, Taiwan, 1 Jul. 2017. Others: China: 1 ñ (18.0 × 14.5 mm), NCHUZOOL 17080, Hougang, Xiapu, Fujian, coll. H.- T. Shih and P.-Y. Hsu et al., 4 Sep. 2017; 1 ò (16.4 × 13.5 mm), ZRC 2002.0561, Xiamen, Fujian, 22 Sep. 2002; 1 ò (18.7 × 15.7 mm), ZRC 2023.0198, Xiamen, Fujian, 1 May 2002; 1 ò (22.9 × 19.2 mm), NCHUZOOL 17079, Yalong Bay, Sanya, Hainan, 28 Jun. 2004; 4 ññ (19.1 × 15.9, 14.7 × 12.2, 14.5 × 11.4, 14.1 × 11.3 mm), NCHUZOOL 16395, Qinzhou, Guangxi, 4 Sep. 2017. Taiwan: 1 ò (10.0 × 8.0 mm), 1 ñ (12.7 × 10.4 mm), NCHUZOOL 16204, Wujiang R. estuary, Kinmen, coll. H.- T. Shih and P.-Y. Hsu et al., 29 Jun. 2018; 1 ò (23.3 × 18.9 mm), NCHUZOOL 16212, Caiyuan, Magong City, Penghu County, 30 Aug. 2014; 1 ò (25.8 × 22.6 mm), NCHUZOOL 17112, Caiyuan, Magong City, Penghu County, coll. J.-J. Li, 21 Jul. 2022. Vietnam: 1 ò (21.0 × 17.5 mm), NCHUZOOL 17074, Dong Rui, Quang Ninh, coll. H.- T. Shih and P.-Y. Hsu et al., 9 Oct. 2017; 5 òò (21.8 × 18.7, 19.3 × 16.5, 19.7 × 16.5, 14.4 × 11.5, 12.0 × 9.3 mm), 1 juvenile (9.2 × 7.6 mm), NCHUZOOL 17072, Dong Rui, Quang Ninh, coll. H.- T. Shih and P.-Y. Hsu et al., 9 Oct. 2017; 1 ò (15.9 × 13.6 mm), NCHUZOOL 17073, Dong Rui, Quang Ninh, coll. P.-Y. Hsu et al., 8 Oct. 2017; 4 òò (18.1 × 15.3, 17.9 × 15.3, 16.8 × 13.9, 14.9 × 12.6 mm), 1 ñ (17.1 × 14.4 mm), NCHUZOOL 17078, Dong Rui, Quang Ninh, coll. H.- T. Shih and P.-Y. Hsu et al., 9 Oct. 2017; 1 ñ (18.5 × 15.2 mm), NCHUZOOL 17071, Dong Rui, Quang Ninh, coll. T. S. Nguyen, 2016; 4 òò (15.2 × 12.1, 14.5 × 12.1, 13.7 × 10.6, 11.1 × 9.1 mm), 6 ññ (15.5 × 13.0, 14.8 × 13.0, 14.7 × 11.7, 14.2 × 11.1, 13.2 × 10.9, 12.9 × 10.4 mm), NCHUZOOL 17075, Mui Chua, Tien Lang, coll. H.- T. Shih and P.-Y. Hsu et al., 8 Oct. 2017; 3 òò (23.3 × 19.9, 19.1 × 15.9, 13.7 × 11.1 mm), 2 ññ (17.1 × 13.8, 10.3 × 8.5 mm), 1 ovig. ñ (13.6 × 11.6 mm), NCHUZOOL 17077, Mui Chua, Tien Lang, coll. H.- T. Shih and P.-Y. Hsu et al., 10 Oct. 2017; 1 ñ (12.9 × 10.1 mm), NCHUZOOL 17114, Nha Trang (12°19.995N, 109°12.284E), coll. I.-H. Chen et al., 23 Nov. 2010.

Diagnosis: Carapace subrectangular ( Fig. 4A, E ), 1.24–1.30 times broader than long (N = 6), body relatively slightly vaulted; front moderately downwards, sloping forwards, deflexed part of front relatively longer in frontal view ( Figs. 4C , 9C ). Postfrontal separated into 4 lobes, longitudinally wider, lower in frontal view; median lobes prominent, lateral lobes indistinct in frontal view. Anterolateral margin with 1 tooth behind external orbital tooth, lateral margin of external orbital tooth relatively straight. Chelipeds homochelous, large, robust; palm with 2 transverse pectinate crests on upper surface ( Fig. 4A ), secondary crest often absent in female; distal (primary) crest composed of 17–23 tall, broad corneous teeth (18 (left) and 19 (right) on male holotype); secondary crest well developed, with 8–22 corneous teeth (16 (left) and 17 (right) on male holotype). Dorsal surface of chelar dactylus with 11–14 distinct, slightly transversely broadened tubercles, proximal 1 or 2 tubercle(s) smallest but distinct, tubercles without ringed grooves on dorsal surface; 1 row of ca. 9–16 small rounded tubercles on proximal part of inner edge of dorsal surface ( Figs. 4F , 10D ). Male pleon ( Fig. 4B, G ) triangular. G1 ( Fig. 4H–K ) relatively stout, straight; apical process long, slender, corneous part ( Figs. 4I, J , 11D ) long, slender, bent at angle of ca. 60° to vertical axis (N = 3), ending in rounded tip. Vulva ( Figs. 4M , 12B ) with slightly elongated semicircular sternal vulvar cover; sunken on mesial part.

Size: Largest male CW 25.8 mm (NCHUZOOL 17112); largest female CW 19.1 (NCHUZOOL 16395); smallest ovigerous female CW 11.3 mm (NCHUZOOL 17070).

Color in life: Usually carapace creamy green, with dark spots and short lines; legs dark brown; palm orange red, fingers deep red ( Fig. 7F–H ; Table 3).

Etymology: This species is named after its distribution in the continental regions of East Asia and Vietnam ( Fig. 1 ).

Distribution: South China (Fujian, Guangdong, Hong Kong, Hainan, Guangxi); Taiwan (Kinmen; Penghu) and Vietnam ( Fig. 1 ).

Remarks: Parasesarma continentale is very similar to P. chiahsiang in the large specimens (CW> 20 mm), especially in the characters of the postfrontal lobes (lobes longitudinally wider and lower in frontal view) ( Figs. 4C , 5C , 9C, G ), but can be distinguished most reliably by the external orbital tooth and structure of the G1s. In P. continentale , the lateral margin of the external orbital tooth is usually straight ( Fig. 4A, E ) [vs. often slightly curved in P. chiahsiang ( Fig. 6A, E )] and the corneous part of the G1 is longer and more slender ( Figs. 4I, J , 11D ) [vs. shorter and stouter in P. chiahsiang ( Figs. 6I, J , 11F )]. In medium-sized specimens (CW about 13–20 mm), P. continentale and P. bidens are more similar, but can be distinguished by the postfrontal lateral lobes and the G1s ( Table 3): the postfrontal lateral lobes are relatively indistinct and lower in frontal view in P. continentale (vs. relatively distinct and higher in P. bidens ) and the corneous part of the G1 is longer and more slender in P. continentale ( Figs. 4I, J , 11D ) [vs. shorter in P. bidens ( Figs. 3I, J , 11C )].

Parasesarma insulare n. sp. ( Figs. 5 , 8A–D , 9E, F , 10E , 11E , 12C ) urn:lsid:zoobank.org:act:3FBAD663-3435-4E30-85C3-046B8E941277

Sesarma bidens – Bürger 1893: 628 (part?; only Luzon); Parisi 1918: 111 (part?; Danshuei, Taiwan); Hsueh 1996: 37 (part?; Taichung, Taiwan). (not Sesarma bidens De Haan, 1835 ).

Sesarma (Chiromantes) bidens – Oshima 1921: 123 (part?; Pingtung, Taiwan); Balss 1922: 156 (part?; S Taiwan); Maki and Tsuchiya 1923: 179 (part?; Pingtung, Taiwan); Sato 1936: 1621 (part?; Su-ao, Yilan, Taiwan); Sakai 1939: 688, pl. 79(1) (part?; only Danshuei, Taiwan); Horikawa 1940: 30 (part?; Taiwan); Lin 1949: 30 (part?; Taiwan); YC Wu et al. 1962: 202 (part?; N Taiwan); Muraoka 1998: 54 (part?; only Kaohsiung, Taiwan). (not Sesarma bidens De Haan, 1835 ).

Sesarma (Perisesarma) bidens – Fukui et al. 1989: 230 (part?; Taiwan); JT Shih et al. 1991: 126 (part?; Danshuei, Taiwan). (not Sesarma bidens De Haan, 1835 ).

Perisesarma bidens – Liu and CW Li 1994: 106 (part?; Hsinchu City, Taiwan); MS Jeng et al. 1996: 51 (part?; NE Taiwan); CH Wang and Liu 1996a: 119, 3 unnumbered figs. (part?; Taiwan); CH Wang and Liu 1996b: 96, 2 unnumbered figs. (part?; Taiwan); Yu et al. 1996: 15 (part?; Pingtung, Taiwan); Ho and Hung 1997: 97, 2 unnumbered figs. (part?; Hsinchu City, Taiwan); MS Jeng 1997: 18 (part?; Pingtung, Taiwan); MS Jeng et al. 1997: 62 (part?; NE Taiwan); CH Jeng et al. 1998: 61, 1 unnumbered fig. (part?; Taichung, Taiwan); MS Jeng et al. 1998: 60 (part?; NE Taiwan); HT Shih 1998: 75, 2 unnumbered figs. (part?; Taichung, Taiwan); CH Wang and Liu 1998a: 119, 3 unnumbered figs. (part?; Taiwan); CH Wang and Liu 1998b: 134, 2 unnumbered figs. (part?; Taiwan); Hsieh 2000: 119, 2 unnumbered figs. (part?; Taoyuan, Taiwan); JH Lee and Tung 2000: 44, 70, 1 unnumbered fig. on p. 44 (part?; Tainan, Taiwan); Chen 2001: 224, 2 unnumbered figs. (part?; Taiwan); JH Lee 2001: 108: 2 unnumbered figs. (part?; Taiwan); Ng et al. 2001: 43 (part?; only Taiwan main island); Chen 2002: 119, 2 unnumbered figs. (part?; Taiwan); Hsueh 2002: 1344 (part?; Taichung, Taiwan); CH Jeng and MF Wang 2002: 76, 1 unnumbered fig. (part?; W Taiwan); CH Wang and Liu 2003: 119, 3 unnumbered figs. (part?; Taiwan); Chiou et al. 2004: 36, 2 unnumbered figs. (part?; Kaohsiung, Taiwan); JH Lee 2005: 32, 1 unnumbered fig. (part?; Tainan, Taiwan); YT Wang 2009: 137, 1 unnumbered fig. (part?; Tainan, Taiwan); CH Jeng et al. 2010: 67, 5 unnumbered figs. (part?; Taichung, Taiwan); Liu and Wang 2010: 59, 3 unnumbered figs. (part?; Taiwan); JH Lee 2011: 196, 1 unnumbered fig. (part?; Tainan, Taiwan); JH Lee et al. 2013: 94, 2 unnumbered figs. (part?; Tainan, Taiwan); JJ Li and Chiu 2013: 54, 3 unnumbered figs. (part?; Pingtung, Taiwan); Liou 2013: 215 (part?; Taoyuan, Taiwan). (not Sesarma bidens De Haan, 1835 ).

Sesarma plicatum – Kuo 1995: 30, 104, 191, 3 unnumbered figs. (part?; Taiwan) (not Sesarma plicatum Latreille, 1803 ).

Periseama bidens – Liao 2009: 106, 2 unnumbered figs. (part?; Changhua, Taiwan). (not Sesarma bidens De Haan, 1835 ).

Parasesarma bidens – Ng et al. 2017: 105 (part?; only Taiwan main island); JJ Li et al. 2019: 40 (p. 2) (part?; only Taiwan main island); Sasaki 2019: 13068 (part? only Taiwan main island); Shahdadi et al. 2020b: 399 (part?; only Taiwan main island); JJ Li and Chiu 2019a: 78, 2 unnumbered figs. (part?; Pingtung, Taiwan); JJ Li and Chiu 2019b: 2 unnumbered figs. on p. 34 (part?; Pingtung, Taiwan); KC Li et al. 2021: 73 (tables S2, S5) (part?; Taoyuan, Taiwan). (not Sesarma bidens De Haan, 1835 ).

Parasesarma sp. – Shahdadi et al. 2022: e0262122 (p. 3), S1 table (part; Taiwan main island; Philippines).

Material examined: Holotype: 1 ò (23.1 × 20.4 mm), NCHUZOOL 17061, Donggang, Pingtung, Taiwan, coll. J.-J. Li, 26 Jun. 2022 . Paratype: 5 òò (22.7 × 19.3, 20.3 × 17.3, 20.0 × 17.1, 17.4 × 14.4, 12.9 × 10.6 mm), 6 ññ (26.1 × 22.4, 25.5 × 21.8, 20.4 × 17.3, 18.7 × 15.6, 16.6 × 13.7, 14.0 × 11.8 mm), NCHUZOOL 17062, same data as holotype; 1 ò (23.4 × 20.3 mm), 1 ñ (19.4 × 16.4 mm), ZRC 2023.0199, same data as holotype. Others: Taiwan: Yilan: 3 òò (16.7 × 14.2, 15.7 × 13.0, 14.5 × 12.4 mm), 2 ññ (14.2 × 11.1, 13.9 × 11.9 mm), NCHUZOOL 16208, Lanyang R. estuary, coll. P.-Y. Hsu et al., 15 May 2018; 10 òò (22.2 × 19.3–10.3 × 8.8 mm), 2 ññ (17.8 × 14.8, 14.0 × 11.2 mm), 2 ovig. ññ (17.5 × 14.8, 13.6 × 11.2 mm), NCHUZOOL 17109, Lanyang R. estuary, coll. P.-Y. Hsu et al., 15 May 2018; 1 ò (18.1 × 15.5 mm), NCHUZOOL 16216, Lanyang R. estuary, coll. P.-Y. Hsu and G.-C. Guo, 5 Nov. 2011; 3 òò (15.1 × 12.9, 14.6 × 12.3, 13.4 × 11.4 mm), NCHUZOOL 17104, Lanyang R. estuary, 30 May 2022; 1 ò (22.0 × 18.3 mm), NCHUZOOL 13390, Lanyang R. estuary, 22 Nov. 1995; Keelung: 2 òò (15.3 × 12.9, 11.3 × 9.4 mm), NCHUZOOL 17100, National Taiwan Ocean University, coll. P.-Y. Hsu et al., 17 Aug. 2018; New Taipei City: 15 òò (24.1 × 21.1–10.6 × 8.6 mm), 5 ññ (17.9 × 15.0–10.2 × 8.5 mm), 1 ovig. ñ (11.0 × 8.8 mm), 12 juveniles, NCHUZOOL 17095, Danshuei, 24 Mar. 2017; Hsinchu City: 1 ñ (18.4 × 15.5 mm), NCHUZOOL 17126, Water Resource Park, Siangshan, 28 Sep. 2009; Miaoli: 1 ñ (12.8 × 10.7 mm), NCHUZOOL 17130, Jhonggang R. estuary, Houlong, 30 May 2014; 1 ñ (23.7 × 20.3 mm), NCHUZOOL 13389, Yuanli, 5 Mar. 2006; Taichung: 3 òò (19.9 × 16.7, 16.4 × 13.3, 15.9 × 13.2 mm), NCHUZOOL 13394, Wunliao, 20 Aug. 2002; 1 ñ (13.8 × 10.8 mm), NCHUZOOL 17122, Wunliao, 20 Aug. 2002; 1 ò (25.5 × 21.9 mm), NCHUZOOL 17103, Da-an, coll. J.-P. Wang, 15 Jun. 2022; 1 ò (8.1 × 6.7 mm), NCHUZOOL 17120, Dajia R. estuary, Gaomei, 31 May 2014; 2 òò (23.4 × 19.7, 22.0 × 18.2 mm), NCHUZOOL 16203, Gaomei, 9 Jun. 2002; 1 ò (19.2 × 16.7 mm), NCHUZOOL 17132, Gaomei, 1 Aug. 2006; 1 ò (21.7 × 19.0 mm), NCHUZOOL 13393, Gaomei, 18 Nov. 2006; Changhua: 1 ò (12.3 × 9.8 mm), 2 ññ (13.8 × 11.5, 13.0 × 10.2 mm), NCHUZOOL 17128, Shengang, 4 Jun. 2016; 11 òò (20.8 × 17.4–11.5 × 9.4 mm), 3 ññ (14.4 × 11.9, 11.9 × 9.8, 11.1 × 8.7 mm), 1 ovig. ñ (12.4 × 10.6 mm), NCHUZOOL 16210, Shengang, 5 May 2016; 2 òò (21.5 × 18.5, 19.3 × 16.1 mm), NCHUZOOL 16220, Shengang, coll. P.-Y. Hsu et al., 16 Mar. 2019; 2 òò (7.9–19.8 × 7.9–19.8 mm), 1 ñ (6.6–10.6 × 7.9–19.8 mm), NCHUZOOL 13391, Shengang, 16 Nov. 1995; 3 òò (22.1 × 18.6, 18.2 × 15.4, 16.7 × 14.1 mm), NCHUZOOL 17105, Shengang, coll. J.-W. Hsu et al., 16 Jun. 2022; 3 òò (18.9 × 16.3, 17.5 × 13.9, 14.3 × 11.5 mm), 1 ñ (11.6 × 9.3 mm), NCHUZOOL 17123, Siansi, 15 Mar. 2018; 1 ò (19.1 × 16.3 mm), 1 ñ (16.2 × 13.2 mm), NCHUZOOL 17127, Fubao, 16 Jan. 2017; 1 ñ (11.3 × 9.4 mm), NCHUZOOL 17117, Hanbao, 14 Jun. 2014; 5 òò (18.3 × 15.5, 18.0 × 15.5, 14.2 × 12.2, 13.0 × 10.9, 10.6 × 8.5 mm), 3 ññ (15.0 × 11.8, 13.8 × 11.1, 10.6 × 8.7 mm), 1 juvenile, NCHUZOOL 17124, Hanbao, 14 Jun. 2014; 4 òò (20.7 × 17.5, 13.4 × 11.0, 12.3 × 10.2, 11.1 × 8.9 mm), 1 ñ (12.9 × 10.6 mm), NCHUZOOL 17108, Hanbao, 8 Mar. 2016; 1 ò (15.4 × 12.8 mm), NCHUZOOL 16201, Dacheng, 16 Jan. 2017; Chiayi County: 3 òò (18.5 × 15.8, 15.5 × 13.0, 14.8 × 13.1 mm), NCHUZOOL 17111, Dongshih, 24 Jan. 2017; Tainan: 5 òò (15.0 × 12.5, 12.7 × 10.0, 11.5 × 9.3, 11.3 × 9.1, 10.5 × 8.5 mm), 3 ññ (18.8 × 13.9, 13.8 × 11.3, 12.4 × 10.1 mm), 12 juveniles, NCHUZOOL 17116, Cigu, 26 Apr. 2014; 1 ò (16.9 × 14.3 mm), 1 juvenile, NCHUZOOL 17125, Cigu, 26 Apr. 2014. 1 ò (19.7 × 16.2 mm), NCHUZOOL 16202, Cingcaolun, 8 Aug. 1995; 2 òò (17.0 × 13.9, 14.4 × 12.3 mm), NCHUZOOL 16207, Sihcao, coll. P.-Y. Hsu, 19 May 2016; 1 ò (17.6 × 14.5 mm), 1 ñ (10.3 × 8.4 mm), 1 juvenile, NCHUZOOL 17121, Yanshuei R. estuary, coll. L.-Y. Wang, 26 Apr. 2014; 1 ò (11.6 × 9.7 mm), 6 juveniles, NCHUZOOL 17131, Yanshuei R. estuary, 26 Apr. 2014; 2 òò (19.6 × 17.1, 11.9 × 9.7 mm), 2 ññ (19.5 × 15.4, 16.7 × 13.9 mm), 6 juveniles, NCHUZOOL 17118, Cigu, 10 Dec. 2018; 8 òò (23.6 × 19.9, 22.8 × 19.3, 21.3 × 17.6, 20.1 × 17.2, 17.8 × 14.6, 17.5 × 14.2, 15.8 × 13.1, 15.1 × 12.3 mm), 2 ññ (21.4 × 18.1, 18.8 × 15.9 mm), NCHUZOOL 17067, Jiangjun, coll. J.-J. Li, 26 Jun. 2022; Kaohsiung: 1 ò (21.9 × 18.9 mm), NCHUZOOL 17102, Yuanjhonggang, Nanzih, coll. L-Y. Wang, 25 Apr. 2014; 4 òò (18.7 × 15.6, 18.2 × 15.2, 17.4 × 14.5, 16.9 × 14.4 mm), 3 ññ (18.9 × 15.6, 18.3 × 15.0, 17.0 × 14.0 mm), NCHUZOOL 17119, Yuanjhonggang, Nanzih, 25 Apr. 2014; 10 òò (24.5 × 21.1–15.6 × 15.7 mm), NCHUZOOL 13395, Gaoping R. estuary, Linyuan, 29 Apr. 1998; 1 ò (13.0 × 10.9 mm), 1 ñ (14.7 × 12.7 mm), NCHUZOOL 13392, Gaoping R. estuary, Linyuan, coll. H.- T. Shih, 30 Apr. 1998; 3 òò (18.9 × 16.3, 13.7 × 11.6, 11.7 × 9.7 mm), 1 juvenile, NCHUZOOL 17129, Gaoping R. estuary, Linyuan, 29 Nov. 2014; Pingtung: 3 òò (14.6 × 11.9, 14.2 × 11.7, 11.0 × 9.3 mm), 2 ññ (14.2 × 11.9, 12.2 × 10.3 mm), 2 ovig. ññ (12.9 × 10.6, 11.7 × 9.8 mm), 7 juveniles, NCHUZOOL 17101, Linbian, 3 Sep. 2017; 2 òò (18.5 × 15.8, 16.5 × 13.6 mm), NCHUZOOL 15637, Baoli R. estuary, Checheng, 19 Mar. 2016; 5 òò (22.2 × 18.3, 16.9 × 14.1, 15.6 × 13.1, 12.9 × 10.4, 8.8 × 7.2 mm), 1 ovig. ñ (14.3 × 11.7 mm), 1 juvenile, NCHUZOOL 16207, Baoli R. estuary, Checheng, coll. P.-Y. Hsu et al., 11 Jul. 2017; 1 ò (24.3 × 20.6 mm), NCHUZOOL 17060, Baoli R. estuary, Checheng, 11 Dec. 2018; 1 ò (17.5 × 14.2 mm), 1 ñ (11.6 × 9.4 mm), NCHUZOOL 17097, Baoli R. estuary, Checheng, coll. J.-W. Hsu et al., 6 Nov. 2018; 3 òò (23.2 × 19.6, 17.7 × 14.9, 16.4 × 13.8 mm), 3 ññ (19.8 × 17.0, 12.5 × 10.2, 11.8 × 9.4 mm), 3 juveniles, NCHUZOOL 17096, Baoli R. estuary, Checheng, coll. P.-Y. Hsu et al., 6 Nov. 2018; 1 ò (9.3 × 7.8 mm), NCHUZOOL 17099, Baoli R. estuary, Checheng, 5 Sep. 2017; 5 òò (21.1 × 17.9, 20.7 × 17.7, 16.6 × 14.7, 16.3 × 14.3, 15.8 × 13.4 mm), 2 ññ (20.0 × 17.4, 13.9 × 11.2 mm), 2 juveniles, NCHUZOOL 17107, Baoli R. estuary, Checheng, 3 Sep. 2017; 5 òò (19.3 × 16.2, 15.6 × 12.4, 15.2 × 12.6, 14.6 × 11.6, 13.0 × 10.4 mm), 1 ñ (18.9 × 15.7 mm), NCHUZOOL 17098, Baoli R. estuary, Checheng, 11 Jul. 2017; 1 ò (23.0 × 21.3 mm), NCHUZOOL 17110, Baoli R. estuary, Checheng, 18 May 2012; 1 ñ (14.5 × 11.9 mm), NCHUZOOL 16215, Gangkou R. estuary, Hengchun, coll. P.-Y. Hsu et al., 19 Mar. 2018; 4 òò (20.1 × 16.9, 17.7 × 14.4, 15.1 × 12.5, 13.6 × 10.9 mm), 1 ñ (17.7 × 14.2 mm), 3 ovig. ññ (21.0 × 17.1, 19.5 × 16.9, 16.7 × 13.7 mm), NCHUZOOL 17068, Gangkou R. estuary, Hengchun, coll. J.-J. Li, 21 Jun. 2022; Taitung: 1 ò (8.8 × 7.1 mm), NCHUZOOL 16219, Dulanwan, Donghe, coll. P.-Y. Hsu et al., 9 Aug. 2017. Philippines: 1 ò (20.1 × 16.8 mm), ASIZ, Bohol, coll. H.-C. Liu, 26–30 Aug. 2004; 1 ò (14.9 × 12.5 mm), ASIZ, Bohol, coll. H.-C. Liu, 26–30 Aug. 2004; 1 ò (15.6 × 12.1 mm), 1 ñ (16.1 × 13.4 mm), ASIZ, Bohol, coll. H.-C. Liu, 26–30 Aug. 2004; 1 ò (14.2 × 12.0 mm), NCHUZOOL 17106, Camiguin, coll. H.- T. Shih, 22 Nov. 1995. Brunei: 1 ò (16.3 × 13.5 mm), ZRC 2016.04.04, Sungai Belayang, coll. L. Ribero, G. Polgar and C. Damken, 15 Oct. 2013.

Diagnosis: Carapace ( Fig. 5A, E ) subrectangular, 1.21–1.32 times broader than long (N = 11), body relatively slightly vaulted; front moderately downwards, sloping forwards, deflexed part of front relatively shorter in frontal view ( Fig. 5C ). Postfrontal separated into 4 lobes, longitudinally narrower, higher in frontal view; median lobes prominent, lateral lobes distinct in frontal view. Anterolateral margin with 1 tooth behind external orbital tooth, lateral margin of external orbital tooth relatively slightly curved. Chelipeds homochelous, large, robust; palm with 2 transverse pectinate crests on upper surface ( Fig. 5A ), secondary crest often absent in female; distal (primary) crest composed of 11–19 tall, broad corneous teeth (18 (left) and 18 (right) on male holotype); secondary crest well developed, with 7–19 corneous teeth (11 (left) and 12 (right) on male holotype). Dorsal surface of chelar dactylus with 10–14 distinct, slightly transversely broadened tubercles, proximal 1 or 2 tubercle(s) smallest but distinct, tubercles without ringed grooves on dorsal surface ( Figs. 5F , 9E ); 1 row of ca. 10–18 small rounded tubercles on proximal part of inner edge of dorsal surface. Male pleon ( Fig. 5B, G ) triangular. G1 ( Fig. 5H–K ) relatively stout, straight; apical process short, corneous part ( Figs. 5I, J , 11E ) shorter, bent at angle of ca. 60° to vertical axis (N = 3), ending in rounded tip. Vulva ( Figs. 5M , 12C ) with slightly elongated semicircular sternal vulvar cover; sunken on mesial part.

Size: Largest male CW 25.5 mm (NCHUZOOL 17103); largest female CW 26.1 mm (NCHUZOOL 17062); smallest ovigerous female CW 11.0 mm (NCHUZOOL 17095).

Color in life: Usually carapace brown, gray, or yellowish green, with dark spots and short lines or dark brown patches; legs brown; palm orange red, fingers red or deep red ( Fig. 8A–D ; Table 3).

Etymology: This species is named after its distribution in the islands spanning from Taiwan main island, the islands in the central Philippines to northern Borneo ( Fig. 1 ).

Distribution: Taiwan main island, the Philippines, and Brunei in northern Borneo ( Fig. 1 ).

Remarks: In several sites of Taiwan main island, P. insulare is occasionally sympatric with the morphologically similar P. chiahsiang n. sp. ( Fig. 1 ), and therefore identification becomes crucial. For adult specimens, the two species can be distinguished by the characters of the frontal region in both sexes and the G1s of large males (CW> 20 mm). In P. insulare , the deflexed part of the front is shorter in frontal view ( Figs. 5C , 9E ) [vs. longer in P. chiahsiang ( Figs. 6C , 9G )]; the postfrontal lobes are higher in frontal view ( Figs. 5C , 9E ) [vs. lower in P. chiahsiang ( Figs. 6C , 9G )]; and the region near the apical process of the G1 is narrower and tapering in dorsolateral view ( Fig. 5K ) [vs. wider and not tapering in P. chiahsiang ( Fig. 6K )]. Furthermore, both species tend to show different color patterns ( Table 3), which facilitates their identification in the field.

Parasesarma insulare is also morphologically similar to P. bidens . Particularly, the postfrontal region (behind the frontal lobes) of the carapace of both species is flatter in frontal view ( Figs. 3C , 5C ), but can be distinguished by the lateral lobes of the postfrontal region. The lateral parts of lateral lobes of the postfrontal region are indistinct in the frontal view in P. insulare ( Figs. 5C , 9E ) [vs. very distinct in P. bidens ( Figs. 3C , 9A )]. Additionally, P. insulare is distributed throughout the Taiwan main island, the Philippines and northern Borneo, whereas P. bidens is only distributed in Japan and South Korea ( Fig. 1 ).

Parasesarma chiahsiang n. sp. ( Figs. 6 , 8E–H , 9G, H , 10F , 11F , 12D ) urn:lsid:zoobank.org:act:C996E271-06E1-4E20-9F85-BCF07F626103

Perisesarma bidens – KH Hung 2000: 135, fig. 411 (part?; Penghu); Ng et al. 2001: 43 (part?; only Penghu); YL Shen and Jeng 2005: 186, 1 unnumbered fig. (part?; Penghu); Shy et al. 2010: 171, 2 unnumbered figs. (part?; Penghu). (not Sesarma bidens De Haan, 1835 ).

Parasesarma bidens – Ng et al. 2017: 105 (part?; only Penghu); JJ Li et al. 2019: 40 (p. 2) (part?; only Penghu); Shahdadi et al. 2022: e0262122 (p. 3), S1 table (part; only Pingtung, Taiwan). (not Sesarma bidens De Haan, 1835 ).

Material examined: Holotype: 1 ò (25.6 × 21.8 mm), NCHUZOOL 17063, Caiyuan, Magong City, Penghu County, coll. J.-J. Li, 21 Jul. 2022 . Paratype: 6 òò (24.7 × 21.4, 21.0 × 17.5, 18.6 × 15.5, 16.2 × 13.8, 15.7 × 13.1, 11.3 × 9.5 mm), 3 ññ (20.7 × 17.2, 20.2 × 16.6, 19.4 × 16.1 mm), 3 ovig. ññ (19.7 × 16.3, 16.6 × 14.0, 16.0 × 13.6 mm), NCHUZOOL 17089, Caiyuan, Magong City, Penghu County, 30 Aug. 2014; 1 ò (21.0 × 17.5 mm), 1 ñ (17.6 × 14.9 mm), ZRC 2023.0200, Caiyuan, Magong City, Penghu County, 30 Aug. 2014. Others: Penghu: Siyu: 1 ò (15.6 × 13.3 mm), NCHUZOOL 17087, Chihsi, Siyu, 19 May 2007; Baisha: 1 ò (8.5 × 6.8 mm), 1 ñ (8.9 × 6.8 mm), 1 juvenile, NCHUZOOL 17094, Citou, 2 Sep. 2014; 5 òò (11.0 × 9.3, 10.9 × 9.0, 9.2 × 7.8, 8.7 × 7.4, 8.5 × 7.2 mm), 2 ññ (17.1 × 14.2, 10.6 × 8.9 mm), 1 ovig. ñ (10.5 × 9.1 mm), 3 juveniles, NCHUZOOL 17090, Citou, 2 Sep. 2014; Husi: Cingluo: 1 ò (23.0 × 19.8 mm), NCHUZOOL 16205, 23 Aug. 2012; 1 ò (22.0 × 18.7 mm), NCHUZOOL 17086, 16 Oct. 2008; 1 ò (23.4 × 19.3 mm), 1 ñ (21.0 × 17.3 mm), NCHUZOOL 16206,, 1 Sep. 2014; 1 ò (8.1 × 6.7 mm), 2 ññ (21.8 × 18.3, 15.8 × 13.1 mm), NCHUZOOL 17064, 1 Sep. 2014; 2 òò (21.0 × 17.9, 19.5 × 16.5 mm), NCHUZOOL 16211, 23 Aug. 2012; 1 ñ (22.7 × 20.4 mm), NCHUZOOL 17081, 23 Aug. 2012; 1 ò (21.3 × 19.1 mm), NCHUZOOL 17085, 27 June 2006; Magong City: 6 òò (17.8 × 15.0, 17.7 × 14.6, 17.2 × 14.5, 14.8 × 12.5, 12.6 × 10.2, 11.9 × 9.7 mm), 2 ññ (15.9 × 12.9, 15.5 × 12.6 mm), 2 ovig. ññ (16.9 × 14.5, 15.5 × 12.2 mm), NCHUZOOL 15507, Caiyuan, 1 Sep. 2014; 1 ò (23.3 × 19.8 mm), NCHUZOOL 17113, Caiyuan, coll. J.-J. Li, 21 July 2022; 1 ñ (22.8 × 18.4 mm), NCHUZOOL 17084, Caiyuan, coll. J.-J. Li, 21 July 2022; 6 òò (20.8 × 17.4, 18.5 × 15.4, 16.9 × 14.2, 16.9 × 14.0, 13.2 × 11.0, 11.6 × 9.6 mm), 2 ññ (20.2 × 15.6, 14.1 × 11.2 mm), 4 ovig. ññ (19.7 × 17.0, 16.5 × 13.9, 14.9 × 12.9, 12.1 × 9.7 mm), NCHUZOOL 16213, Shuanhuyuan, 30 Aug. 2014; 3 òò (16.6 × 13.4, 16.0 × 13.4, 14.2 × 11.5 mm), 2 ññ (16.9 × 14.0, 14.2 × 11.4 mm), NCHUZOOL 17093, Tiesian, 4 Sep. 2014; 1 ò (13.2 × 10.8 mm), NCHUZOOL 17088, Tiesian, 1 Sep. 2014; 1 ò (8.6 × 6.8 mm), NCHUZOOL 17092, Wukan, 30 Aug. 2014. Taiwan main island: 1 ñ (12.0 × 10.0 mm), NCHUZOOL 17056, Lanyang R. estuary, Yilan, coll. P.-Y. Hsu and G.-C. Guo, 5 Nov. 2011; 1 ò (15.3 × 12.6 mm), NCHUZOOL 15508, 1 ò (23.2 × 19.6 mm), NCHUZOOL 17082, Da-an, Taichung, coll. J.-P. Wang, 15 Jun 2022; 1 ò (25.8 × 21.0 mm), NCHUZOOL 16214, Gaomei, Taichung, coll. L. Tseng, 29 May 2004; 1 ò (21.2 × 17.4 mm), NCHUZOOL 17083, Baoli R. estuary, Checheng, Pingtung, 11 Jul. 2017. Gueishan Island, Toucheng, Yilan: 26 Jun. 2004; 7 òò (25.8 × 21.5, 24.8 × 20.7, 24.5 × 19.5, 23.5 × 19.4, 22.7 × 19.0, 21.6 × 17.9, 19.9 × 16.6 mm), 4 ññ (21.0 × 16.8, 17.5 × 14.4, 14.8 × 12.1, 11.9 × 9.4 mm), 2 ovig. ññ (21.5 × 17.6, 17.1 × 14.2 mm), NCHUZOOL 17139, 4 òò (18.1 × 15.0, 17.6 × 14.9, 16.6 × 13.7, 14.9 × 12.2 mm), 2 ññ (20.4 × 17.0, 15.0 × 12.0 mm), NCHUZOOL 17140, coll. J.-J. Li, 23 Sep. 2022.

Diagnosis: Carapace ( Fig. 6A, E ) subrectangular, 1.20–1.29 times broader than long (N = 9), body relatively vaulted; front moderately downwards, sloping forwards, deflexed part of front relatively longer in frontal view ( Fig. 6C ). Postfrontal separated into 4 lobes, longitudinally wider, lower in frontal view; median lobes prominent, lateral lobes indistinct in frontal view. Anterolateral margin with 1 tooth behind external orbital tooth, lateral margin of external orbital tooth relatively slightly curved. Chelipeds homochelous, large, robust; palm ( Fig. 6A ) with 2 transverse pectinate crests on upper surface, secondary crest often absent in female; distal (primary) crest composed of 13–23 tall, broad corneous teeth (16 (left) and 16 (right) on male holotype); secondary crest well developed, with 7–15 corneous teeth (15 (left) and 14 (right) on male holotype). Dorsal surface of chelar dactylus with 10–15 distinct, slightly transversely broadened tubercles, proximal 1 or 2 tubercle(s) smallest but distinct, tubercles without ringed grooves on dorsal surface; 1 row of ca. 12–17 small rounded tubercles on proximal part of inner edge of dorsal surface ( Figs. 6F , 10F ). Male pleon ( Fig. 6B, G ) triangular. G1 ( Fig. 6H–K ) relatively stout, straight; apical process long, corneous part ( Figs. 6I, J , 11F ) long, bent at angle of ca. 60° to vertical axis (N = 3), ending in rounded tip. Vulva ( Figs. 6M , 12D ) with slightly elongated semicircular sternal vulvar cover; sunken on mesial part.

Size: Largest male CW 25.8 mm (NCHUZOOL 16214); largest female CW 22.8 mm (NCHUZOOL 17084); smallest ovigerous female CW 10.5 mm (NCHUZOOL 17090).

Color in life: Usually carapace yellow to greenish-yellow, with dark spots and short lines; legs brown; palm orange red, fingers deep red ( Fig. 8E–H ; Table 3).

Etymology: The species is named after late ChiaHsiang Wang, a former researcher in the Taiwan Museum, who has contributed to the crab studies in Taiwan since 1980s (Ng 2008; Ng et al. 2009). The name is used as a noun in apposition.

Distribution: This species is mainly distributed in the Penghu Islands, Taiwan, but is also occasionally found in Taiwan main island, as well as Gueishan Island, an offshore islet located in the northeast of Taiwan ( Fig. 1 ).

Remarks: Parasesarma chiahsiang n. sp. is very similar to P. continentale and P. insulare , but can be distinguished by the characters of the fontal and postfrontal lobes, as well as the G1s ( Table 3). In P. chiahsiang and P. continental, the deflexed part of the front region is longer (in frontal view) ( Figs. 4C , 6C , 9C, 9G ) [vs. shorter in P. insulare ( Figs. 5C , 9E )] and the postfrontal lateral lobes are lower and indistinct (in frontal view) ( Figs. 4C , 6C , 9C, 9G ) [vs. higher and distinct in P. insulare ( Figs. 5C , 9E )], but the postfrontal lobes are lower and distinct in P. chiahsiang ( Figs. 6C , 9G ) [vs. lower and indistinct in P. continentale ( Figs. 4C , 9C ); higher and more distinct in P. insulare ( Figs. 5C , 9E )] and the corneous part of G1 is longer in P. chiahsiang ( Figs. 6I, J , 11F ) [vs. longest and slender in P. continentale ( Figs. 4I, J , 11D ) and shorter in P. insulare ( Figs. 5I, J , 10E )].

Key to the species of the Parasesarma bidens species complex

1a. Tubercles with ringed grooves on dorsal surface of chelar dactylus ( Fig. 10A, B ; JJ Li et al. 2019: fig. 8B, E) ................... 2

1b. Tubercles without ringed grooves on dorsal surface of chelar dactylus ( Figs. 3F , 4F , 5F , 6F , 10C–F ) ....................................... 3

2a. Tubercles of chelar dactylus more ovate. G1 with chitinous tip proportionately narrower; vulvae with relatively larger operculum (JJ Li et al. 2019: fig. 8B–D) ......................................................... ........................................... P. sanguimanus Li, Shih & Ng, 2019

2b. Tubercles of chelar dactylus more rounded. G1 with chitinous tip proportionately wider; vulva with relatively smaller operculum (JJ Li et al. 2019: fig. 8E–G) ... P. cricotum ( Rahayu & Davie, 2002)

3a. Lateral lobes (especially lateral part) of postfrontal region very distinct and relatively higher in frontal view ( Figs. 3C , 9B ) ......... ............................................................. P. bidens (De Haan, 1835)

3b. Lateral lobes (especially lateral part) of postfrontal region indistinct and relatively lower in frontal view ( Figs. 4C , 5C , 6C , 9C, E, G ) ..................................................................................... 4

4a. Deflexed part of front shorter longitudinally in frontal view; postfrontal lobes higher and distinct in frontal view ( Figs. 5C, E , 9E ) ..................................................................... P. insulare n. sp.

4b. Deflexed part of front longer longitudinally in frontal view; postfrontal lobes lower and indistinct in frontal view ( Figs. 4C, E , 6C, E , 9C, G ) .............................................................................. 5

5a. Postfrontal lobes relatively indistinct in frontal view ( Figs. 4C , 9C ); lateral margin of external orbital tooth often straight ( Fig. 4E ). G1 with corneous part longer, more slender ( Figs. 4I–J , 11D ) ............................................................ P. continentale n. sp.

5b. Postfrontal lobes relatively distinct in frontal view ( Figs. 6C , 9G ); lateral margin of external orbital tooth often slightly curved ( Fig. 6E ). G1 with corneous part shorter, stouter ( Figs. 6I–J , 11F ) ....................................................................... P. chiahsiang n. sp.

Molecular analyses

This study analyzed 121 specimens of the P. bidens species complex, including 10 specimens of P. bidens , 19 of P. continentale , 50 of P. insulare , 31 of P. chiahsiang , 2 of P. cricotum , and 9 of P. sanguimanus ( Table 1). The phylogeny based on the combined 16S, COI, and 28S from 23 specimens and GenBank sequences (including related species) with support values of BI, ML, and MP is shown in figure 13. There are 16 haplotypes of 16S, 20 haplotypes of COI, and six haplotypes of 28S ( Fig. 13 ; Table 1). The Parasesarma bidens species complex is monophyletic ( Fig. 13 ) with high support values (except for the lower values for P. bidens ) and six clades corresponding to six species: P. continentale , P. chiahsiang , P. bidens , P. cricotum , P. insulare , and P. sanguimanus . Among them, P. continentale , P. chiahsiang , and P. bidens form a major clade (sister to P. cricotum ), whereas P. insulare and P. sanguimanus form another major clade.

For the combined 16S and COI phylogeny from 130 specimens and GenBank sequences (including related species), there are 24 haplotypes of 16S and 37 haplotypes of COI ( Fig. 14 ; Table 1). The topology shows two lineages, one of which is composed of six clades from the West Pacific, whereas the other contains three clades from the Indian Ocean. Based on the combined 16S and COI dataset, the phylogeny shows a similar topology ( Fig. 14 ), including the monophyly of the Parasesarma bidens species complex with high support values; six clades corresponding to six species; and high support values in five species, except for the lower values for P. bidens . In figure 14, P. continentale , P. chiahsiang , and P. bidens form a major clade with the sister P. cricotum , whereas P. insulare and P. sanguimanus form another major clade. Furthermore, each species has unique COI haplotypes and most of the 16S haplotypes (except for the 16S haplotype “Pbh-

Pc-4+Pc-C1+P28-2 ( Hong Kong) Pc- Pc- 1 1 + 1 2 + 1 + + Ph-C + Ph-C Ph-C Pc-C Pc-C 1 1 2 + 4 + 1 + P + + P P 28 P P 28 28 28 28 - - 3 - 2 - - 2 4 2 ((Penghu Penghu (((x Kinmen Hong 2) (Penghu Kong))))) P P.. chiahsiang continentale n n. sp. sp.. 2 + 1+ + Pb-C Pb-C Pb-C 2 1 1 + + + P P P 28 28 28 -3 - -1 1 ((Ryukyus (Ryukyus Kyushu,)) Japan) P. bidens Pcr-C1+P28-1 (West Papua) P. cricotum Pi-C Pi-C2 1+ + P P 28 28 - - 1 1 ((S NE Taiwan Taiwan)) P. insulare Pi-C1+P28-2 (S Taiwan) n. sp. 4 P P + 28 28 Pi-C - - 2 1 ((S S 11 Taiwan Taiwan +P28-)) 1 (C Philippes P.) sanguimanus +P28-1 (C Philippines) 400903+MF554648 ( Kenya) P. guttatum (W Thailand) P. bengalense 1 (W India) Ppe+Ppe-C+P28-1 ( Singapore) P. peninsulare +P28-3 ( Vietnam) P. eumolpe Pse +Pse-C+P28-6 (S Ryukyus) P. aff. lividum

1” shared by P. bidens and P. chiahsiang ). Based on the substitution rates of 16S and COI, the divergence time estimation for the main nodes ( Fig. 14 ) indicates that the P. bidens species complex began to separate from the Indian Ocean species ca. 2.68 million years ago (mya). The divergence time between the two major clades (“ P. bidens + P. continentale + P. chiahsiang + P. cricotum ” and “ P. insulare + P. sanguimanus ”) is ca. 2.02 mya. P. cricotum separated from its closely related species roughly 1.55 mya, which is close to the 1.35 mya between P. insulare and P. sanguimanus . The divergence among P. continentale , P. chiahsiang , and P. bidens occurred relatively more recently, approximately 0.70–0.85 mya.

A total of 137 specimens (and GenBank sequences) were used to construct the COI haplotype network ( Fig. 15 ), including haplotypes from Jeju Island, South Korea. In this study, P. insulare is well separated from other species, whereas P. bidens , P. continentale , and P. chiahsiang are closely related. P. chiahsiang is separated from P. bidens and P. continentale by ≥ 6 and ≥ 9 steps, respectively, whereas P. bidens is separated from P. continentale by ≥ 9 steps. In P. bidens , one haplotype is shared by nine specimens from the main islands of Japan and Ryukyus and another haplotype from Okinawa; three haplotypes from South Korea are different from the Japanese ones by ≥ 2 steps. In P. chiahsiang , one haplotype is shared by 28 specimens from Penghu and three sites in Taiwan main island, with two haplotypes unique to Penghu and two haplotypes unique to Taiwan main island. In P. continentale , 4 haplotypes are found from southeastern China to southern Vietnam, including Hainan Island, whereas one haplotype “Pc-C3” from Penghu (2 specimens) is found to have 4 different steps. A total of 11 haplotypes are identified in P. insulare , with one haplotype shared by 38 specimens from Taiwan, the central Philippines and Brunei, and one haplotype from the central Philippines with a ≥ 5 steps different from the others.

Table 2 summarizes the pairwise nucleotide divergences of K2P distances and bp differences among COI haplotypes of the Parasesarma species. The maximum intraspecific nucleotide divergences (and bp differences) of P. bidens , P. chiahsiang , P. continentale , and P. insulare are ≤ 0.61% (≤ 4 bp), ≤ 0.3% (≤ 2 bp), ≤ 0.92% (≤ 6 bp), and ≤ 1.23% (≤ 8 bp), respectively. The ranges of interspecific divergences (and bp differences) are 0.92%–4.59% (6–29 bp) among the four aforementioned species, with the minimum divergence 0.92% (6 bp) between P. bidens and P. chiahsiang .

Figures

Fig. 2. Lectotype and paralectotype of Grapsus (Pachysoma) bidens De Haan 1835.A, lectotype male (RMNH 145); B, paralectotype female (RMNH 144); C, paralectotype male (CW 30.1 mm; RMNH).A–C, courtesy of Takao Yamaguchi.

Fig. 3. Parasesarma bidens (De Haan, 1835). A–K, male (CW 22.0 mm; NCHUZOOL 15511). L, M, female (CW 26.8 mm; NCHUZOOL 15511). A, Dorsal view; B, ventral view; C, frontal view; D, outer view of right cheliped; E, carapace; F, dorsal surface of right chelar dactylus; G, male pleon; H– K, right G1 (H, I, dorsal view; J, K, dorsolateral view); L, female pleon; M, right vulva.

Fig. 7. Color in life of Parasesarma sanguimanus Li, Shih & Ng, 2019 (A, B), P. bidens (De Haan, 1835) (C–E) and P. continentale n. sp. (F–H). A, B, Gangkou R. estuary, Pingtung, Taiwan; C, Ishigaki, Ryukyus, Japan; D, Kanagawa, Japan; E, Miyako Island, Ryukyus, Japan; F–H, Tung Chung, Lantau Island, Hong Kong, 2 Jun. 2019. All of the specimens were either not collected or cataloged. C–E, courtesy of Taisuke Iwano.

Fig. 9. Different views of the frontal region (some setae removed to expose different areas). A, C, E, G, frontal view; B, D, E, H, dorsal view. A, B, P. bidens (CW 22.0 mm, NCHUZOOL 15511); C, D, P. continentale n. sp. (CW 18.5 mm, NCHUZOOL 17065). E, F, P. insulare n. sp. (CW 23.1 mm, NCHUZOOL 17061). G, H, P. chiahsiang n. sp. (CW 25.6 mm, NCHUZOOL 17063). Scale bars = 5 mm.

Fig. 10. Dorsal surface of male chelar dactyli. A, P. cricotum (CW 18.4 mm, NCHUZOOL 16400) (left chela, horizontally flipped for comparison with right chelar dactyli of others). B, P. sanguimanus (CW 17.5 mm, NCHUZOOL 15525). C, P. bidens (CW 22.0 mm, NCHUZOOL 15511). D, P. continentale n. sp. (CW 18.9 mm, ZRC). E, P. insulare n. sp. (CW 23.1 mm, NCHUZOOL 17061). F, P. chiahsiang n. sp. (CW 25.6 mm, NCHUZOOL 17063). Scale bars = 3 mm.

Fig. 11. Tips of right G1s (dorsal view). A, P. cricotum (CW 18.4 mm, NCHUZOOL 16400). B, P. sanguimanus (CW 17.5 mm, NCHUZOOL 15525). C, P. bidens (CW 22.0 mm, NCHUZOOL 15511). D, P. continentale n. sp. (CW 18.9 mm, ZRC). E, P. insulare n. sp. (CW 23.2 mm, NCHUZOOL 17096). F, P. chiahsiang n. sp. (CW 21.0 mm, ZRC). Scale bars = 1 mm.

Fig. 12. Right vulvae (ventral view). A, P. bidens (CW 26.8 mm, NCHUZOOL 15511). B, P. continentale n. sp. (CW 18.7 mm, NCHUZOOL 17066). C, P. insulare n. sp. (CW 26.1 mm, NCHUZOOL 17062). D, P. chiahsiang n. sp. (CW 21.8 mm, NCHUZOOL 17064). Scale bars = 1 mm.

Fig. 1. A, Map of the distributions of Parasesarma capensis, P. guttatum, P. bengalense, P. continentale n. sp., P. chiahsiang n. sp., P. bidens, P. insulare n. sp., P. sanguimanus, and P. cricotum. B, Distributional map of the five species of the Parasesarma bidens species complex around Taiwan. The solid purple and blue circles indicate occasional collections of P. continentale and P. chiahsiang in other regions, respectively. 1, Jeju Island, South Korea; 2, Penghu Islands, Taiwan; 3, Fujian, China; 4, Guangdong, China; 5, Hainan Island, China; 6, Guangxi, China; 7, Dong Rui, Quang Ninh, Vietnam; 8, Nha Trang, Vietnam; 9, Brunei.

Fig. 5. Parasesarma insulare n. sp. A–K, male, holotype (CW 23.1 mm; NCHUZOOL 17061). L, M, female, paratype (CW 26.1 mm; NCHUZOOL 17062). A, Dorsal view; B, ventral view; C, frontal view; D, outer view of left cheliped; E, carapace; F, dorsal surface of left chelar dactylus; G, male pleon; H–K, right G1 (H, I, dorsal view; J, K, dorsolateral view); L, female pleon; M, right vulva.

Fig. 4. Parasesarma continentale n. sp. A–K, male, holotype (CW 18.5 mm; NCHUZOOL 17065). L, M, female, paratype (CW 18.7 mm; NCHUZOOL 17066). A, Dorsal view; B, ventral view; C, frontal view; D, outer view of left cheliped; E, carapace; F, dorsal surface of left chelar dactylus; G, male pleon; H–K, right G1 (H, I, dorsal view; J, K, dorsolateral view); L, female pleon; M, right vulva.

Fig. 6. Parasesarma chiahsiang n. sp. A–K, male, holotype (CW 25.6 mm; NCHUZOOL 17063). L, M, female (CW 21.8 mm; NCHUZOOL 17064). A, Dorsal view; B, ventral view; C, frontal view; D, outer view of left cheliped; E, carapace; F, dorsal surface of left chelar dactylus; G, male pleon; H–K, right G1 (H, I, dorsal view; J, K, dorsolateral view); L, female pleon; M, right vulva.

Fig. 8. Color in life of Parasesarma insulare n. sp. (A–D) and P. chiahsiang n. sp. (E–H). A, C, Baoli R. estuary, Pingtung, Taiwan; B, Gangkou R. estuary, Pingtung; D, Gaoping R. estuary, Kaohsiung, Taiwan; E, Citou, Penghu, Taiwan; F, H, Cinglou, Penghu, Taiwan; G, Caiyuan, Penghu, Taiwan. F, male (NCHUZOOL 17086); other specimens were not collected.

Fig. 13. Bayesian inference (BI) tree of the Parasesarma bidens species complex and other related congeneric species based on the combined 28S, 16S, and COI markers. The values at the nodes are the support values for BI, maximum likelihood (ML), and maximum parsimony (MP) analyses. Only values> 50% are shown. See Table 1 for haplotype names.

Fig. 14. Bayesian inference (BI) tree of the Parasesarma bidens species complex and other related congeneric species based on the combined 16S and COI markers. The values at the nodes are the support values for BI, maximum likelihood (ML), and maximum parsimony (MP) analyses. Only values> 50% are shown. The estimated divergence times are shown in reverse color next to the main nodes. See Table 1 for haplotype names.

Fig. 15. Genealogical network for the COI haplotypes observed from the Parasesarma bidens species complex and other related congeneric species. The unlabeled nodes indicate inferred haplotypes that were not identified in the sampled populations. See table 1 for haplotype names.