Candidiopotamon penglai, Shih & Naruse & Schubart, 2023

Shih, Hsi-Te, Naruse, Tohru & Schubart, Christoph D., 2023, Molecular evidence and differences in gonopod morphology lead to the recognition of a new species of the freshwater crab genus Candidiopotamon Bott, 1967 (Crustacea, Brachyura, Potamidae) from eastern Taiwan, ZooKeys 1179, pp. 169-196 : 169

Candidiopotamon penglai sp. nov.

Figs 4C-F , 5E-H , 6 , 7

Potamon rathbuni - Chiu 1964: 67 (part).

Candidiopotamon rathbuni - Minei 1974: 246, figs 7-9 (part); CH Wang 1984: 41; Yu et al. 1996: 9, 29, fig. 10; MS Jeng 1998: 86, 1 unnumbered fig.; Shy and Yu 1999: 94, 3 unnumbered figs, "fig. 31" on p. 106 (part); Ng 2000: 249 (part); Ng et al. 2017: 76; Shy et al. 2020: 2, figs 11A, 13, 14, 16, 17 (part); Li and Chiu 2019a: 103, 3 unnumbered figs; Li and Chiu 2019b: 2 unnumbered figs on p. 56; Shy et al. 2020: 2, figs 2E, 14E (part); SW Wang et al. 2021: 32, pl. 3E.

Candidiopotamon rathbunae - Ng 2000: 249 (part); Chen et al. 2001: 43, 2 unnumbered figs on p. 43, 46 (part); Lee 2001: 145, 2 unnumbered figs (part); Ng et al. 2001: 49 (part); Chen et al. 2003: 29, 5 unnumbered figs (part); Shih et al. 2006: 983 (part); Ng et al. 2008: 161 (part); Shy and Lee 2009: 207, 10 unnumbered figs (part); Li and Chiu 2013: 70, 3 unnumbered figs; Chiu et al. 2015: 202, 227, 1 unnumbered fig. on p. 202 (part); Ho 2015: 141, 2 unnumbered figs (part); Sasaki 2019: 11552 (part).

Type material.

Taiwan - Holotype: male, 38.4 × 33.4 mm, NCHUZOOL 12951, Ji-an, Hualien, coll. H.-C. Liu, 4 May 2000. - Paratypes: 1 male, 35.6 × 30.5 mm, RUMF-ZC-8164, 1 female, 18.0 × 15.8 mm, NCHUZOOL 12932, collection data same as for holotype; 1 female, 34.3 × 29.6 mm, RUMF-ZC-8165, Shueiyuandi, Shoufeng, Hualien, coll. N.-H. Jang-Liaw, 5 Mar. 2002; 1 male, 23.4 × 20.0.5 mm, NCHUZOOL 12952, Liyu Lake, Shoufeng, Hualien, coll. H.-T. Shih, 26 Jan. 2007; 1 male, 27.5 × 24.2 mm, NCHUZOOL 15213, Liyu Lake, Shoufeng, Hualien, coll. H.-T. Shih, 28 Jan. 2007; 1 male, 36.4 × 30.9 mm, NCHUZOOL 15224, 1 male, 27.0 × 23.8, NCHUZOOL 15226, 1 female, 36.5 × 31.4, NCHUZOOL 15225, Liyu Lake, Shoufeng, Hualien, coll. HTS’s lab students, 13 Apr. 2023; 1 male, 28.3 × 24.8 mm, 1 female, 35.2 × 31.6 mm, ZRC 2023.0309, Liyu Lake, Shoufeng, Hualien, coll. HTS’s lab students, 13 Apr. 2023.

Other material.

Taiwan - 1 male, 23.9 × 20.1 mm, NCHUZOOL 15227 , 1 male, 29.3 × 27.6 mm, NCHUZOOL 15228, 1 male, 33.1 × 29.7 mm, NCHUZOOL 15229, Jili Lake, Guangfu , Hualien, coll. HTS’s lab students, 12 Apr. 2023 ; 1 female, 37.7 × 33.6 mm, NCHUZOOL 15230, Luoshan, Fuli , Hualien, coll. HTS’s lab students, 11 Apr. 2023 ; 2 males, 35.9 × 30.6, 37.0 × 31.9 mm, 2 females, 27.6 × 23.5, 36.7 × 31.9 mm, RUMF-ZC-56, Jingpu , Hualien, coll. M.-Y. Liu, 18 Jun. 2001 ; 2 males, 33.0 × 28.9, 30.4 × 26.5 mm, NSMT-Cr 15170, Jingpu , Hualien, coll. M.-Y. Liu, Jan. 2001 ; 1 male, 31.7 × 26.7 mm, NCHUZOOL 15221, Chenggong , Taitung, coll. N.-H. Jang-Liaw, 6 Mar. 2002 ; 3 males, 28.2 × 23.3-34.0 × 28.8 mm, 2 females, 16.4 × 13.6, 38.3 × 31.0 mm, NCHUZOOL 12931, Taimali , Taitung, coll. H.-C. Liu, 22 Aug. 1997 ; 4 males, 28.6 × 24.8-33.7 × 29.1 mm, 1 female, 32.5 × 27.0 mm, NCHUZOOL 15206, Sansiantai, Chenggong , Taitung, coll. H.-C. Liu and H.-L. Hsu, 5 Sep. 1997 ; 2 males, 31.4 × 25.9, 27.0 × 23.3 mm, NCHUZOOL 12933, Lijia, Beinan , Taitung, 1250 m a.s.l, coll. S.-P. Wu, 22 Aug. 2001 ; 1 male, 28.4 × 24.6, NCHUZOOL 12938, 32.9 × 28.7 mm, ZRC 2003.0036, Luanshan, Yanping , Taitung, coll. H.-T. Shih, 10 Jan. 2001 ; 4 males, 29.0 × 24.6-35.6 × 29.3 mm, 1 female, 21.9 × 18.4 mm, NCHUZOOL 15218, Taiban, Daren , Taitung, coll. H.-C. Liu, 22 Apr. 1995 ; 1 female, 44.7 × 35.9 mm, NCHUZOOL 15210, Dawu , Taitung, coll. H.-C. Liu and C.-H. Wang, 22 Aug. 1997 ; 1 male, 28.9 × 24.1 mm, 1 female, 29.8 × 25.0 mm, NCHUZOOL 12943, Dawu , Taitung, coll. H.-T. Shih, 9 Jan. 2001 ; 2 males, 40.1 × 33.6, 42.9 × 36.2 mm, 1 female, 38.4 × 31.5 mm, NCHUZOOL 15207, Danlu, Shihzih , Pingtung, coll. H.-T. Shih, 12 Mar. 1999 ; 1 male, 28.0 × 23.3 mm, NCHUZOOL 15208, Wangsha, Hengchun , Pingtung, coll. H.-T. Shih, 5 Mar. 2000 ; 1 male, 31.0 × 25.2 mm, RUMF-ZC-57, Wangsha, Hengchun , Pingtung, coll. H.-T. Shih, 31 Mar. 1999 ; 2 males, 41.7 × 35.0, 41.9 × 35.0 mm, 1 female, 35.7 × 29.8 mm, NCHUZOOL 15217, Nanrenshan, Manjhou , Pingtung, coll. H.-T. Shih, 19 Oct. 1996 ; 3 males, 37.0 × 30.8-40.6 × 34.7 mm, NCHUZOOL 15204, Nanrenshan, Manjhou , Pingtung, coll. R.-H. Lee, 8 Feb. 2003 ; 1 male, 44.3 × 37.0 mm, ZRC 2003.0037, Nanrenshan, Manjhou , Pingtung, coll. H.-T. Shih, 24 Feb. 1999 ; 1 male, 43.8 × 36.7 mm, RUMF-ZC-58, Kenting, Hengchun , Pingtung, coll. H.-T. Shih, 6 Jan. 2000 ; 1 male, 30.6 × 26.2 mm, 1 female, 35.2 × 29.3 mm, NSMT-Cr 15171, Sihchong R., Mudan , Pingtung, coll. H.-T. Shih, 10 Mar. 1999 ; 1 male, 38.7 × 32.4 mm, 3 females, 38.3 × 33.5-43.6 × 35.9 mm, NCHUZOOL 15209, Nanshih, Shihzih , Pingtung, coll. H.-C. Liu, 22 Jul. 1997 .

Diagnosis.

Carapace subtrapezoidal, CW 1.14-1.24 × CL (mean 1.18, n = 45), dorsal surface almost flat, relatively rough, epigastric and postfrontal cristae distinct, both cristae represented by 1-3 oblique lines of granules, lateral end of postfrontal cristae far apart from epibranchial tooth; external orbital and epibranchial teeth distinct, sharp, directed anteriorly. G1 terminal segment proportionally longer and slender, distal opening directed laterally, distal inner edge with keel-like projection in dorsal view, projection proportionally large, directed more distally; G1 subterminal segment curving inwards (in eastern to southeastern Taiwan populations) or straight (in southern Taiwan populations).

Etymology.

The new species is named after Penglai, the ancient name of Taiwan. It also refers to the fact that the island of Taiwan was formed by the Penglai Orogeny (ca 5 million years ago) ( Teng 1990; Liu et al. 2000), and the ancestral Candidiopotamon most likely colonized Taiwan at that time ( Shih et al. 2006). The species name is used as a noun in apposition.

Coloration

(Figs 4C-F , 5E-H ). Same as C. rathbuni , but young individuals tend to be reddish (e.g. Fig. 5H ).

Distribution

(Fig. 1 ). Candidiopotamon penglai sp. nov. is distributed along the eastern side of the Central Range of Taiwan (except for the northeastern area), i.e., Hualien and Taitung in eastern Taiwan, as well as Hengchun Peninsula (the southern part of Pingtung and the southern tip of Taitung) in southern Taiwan. The type locality of C. penglai sp. nov. is Ji-an, Hualien (Fig. 1 : no. 55).

Habitat.

Same as C. rathbuni .

Remarks.

A detailed morphological comparison reveals that specimens of C. rathbuni from western Taiwan and C. penglai sp. nov. from eastern Taiwan show differences in G1 structure. Candidiopotamon rathbuni has a smaller and more laterally directed keel-like projection on the distal inner part of the terminal segment (Fig. 3D3 ) [vs larger and more distally directed structure in C. penglai (Figs 5C , 6C )]. Furthermore, C. rathbuni show almost straight subterminal segment of G1 (Fig. 3D2 ), whereas those of C. penglai are varied either straight (S clade, Fig. 7 ) or bent (E1, E2 and SE clades, Fig. 6 ) (Figs 1 , 5B , 6B ; see Discussion).

This new species includes clades from eastern Taiwan (E1, E2, SE and S, see Fig. 1 ) that are genetically distinct from C. rathbuni from western Taiwan (NW, W and SW) (Table 2 , Fig. 2 ), with a reliable character of G1 also separating the two species (see above). Within C. penglai sp. nov., there are two forms of the curvature in G1, with the bent form found in the E1, E2 and SE clades, and the straight form in the S clade (Fig. 1 ; see Discussion).

Figures

Figure 1. Collection sites for Candidiopotamon rathbuni (De Man, 1914) (circles) and Candidiopotamon penglai sp. nov. (squares) in Taiwan, as well as other congeners from the Ryukyus, Japan. Different colors indicate sampling sites of clades. Dotted lines indicate the possible biogeographic boundaries between clades NW, W, SW, S, SE, E 1, and E 2, corresponding to the color in Fig. 2; as well as species. The red star and blue star indicate the type localities of C. rathbuni and C. penglai sp. nov., respectively. Three forms of male left G 1 are shown for clades in C. rathbuni and two forms for clades in C. penglai sp. nov.

Figure 2. A Bayesian inference (BI) tree for Candidiopotamon rathbuni (De Man, 1914) and Candidiopotamon penglai sp. nov., as well as outgroups, based on the combined 16 S rDNA and cytochrome oxidase I. Probability values at the nodes represent support values for BI and maximum likelihood (ML). For haplotype names, see Table 1. The color of clades corresponds to the color of collection sites in Fig. 1, which are also shown as the numbers in parenthesis after the haplotype names.

Figure 3. Candidiopotamon rathbuni (De Man, 1914): male (44.6 x 36.8 mm) from Chiayi, western Taiwan (RUMF-ZC- 86) (A - E); male (35.4 x 31.2 mm) from Miaoli, northwestern Taiwan (NCHUZOOL 15194) (F 1); male (36.7 x 31.1 mm) from Chiayi, western Taiwan (NCHUZOOL 15205) (F 2); male (36.3 x 30.7 mm) from Taiwu, Pingtung, southwestern Taiwan (NCHUZOOL 15199) (F 3). A carapace, dorsal view B carapace, frontal view C male major chela, outer view D 1 left G 1, ventral view D 2 left G 1, dorsal view D 3 left G 1 terminal segment, dorsal view E left G 2 F 1 - 3 left G 1 s terminal segment, dorsal view. Scale bars: 10 mm (A - C); 2 mm (D - F). Arrow indicates the keel-like projection on the distal inner edge of the terminal segment.

Figure 4. Color in life of Candidiopotamon rathbuni (De Man, 1914) (A, B) and Candidiopotamon penglai sp. nov. (C-F). A, C, E overall dorsal view B, D, F overall ventral view A, B NCHUZOOL 15181 (male, 28.0 x 23.9 mm, Rihyuetan, Nantou, western Taiwan) C, D NCHUZOOL 15204 (male, 39.7 x 34.4 mm, Nanrenshan, Pingtung, southern Taiwan); NCHUZOOL 15224 (paratype male, 36.4 x 30.9 mm, Liyu Lake, Shoufeng, Hualien, eastern Taiwan).

Figure 5. Color in life of Candidiopotamon rathbuni (De Man, 1914) (A-D) and Candidiopotamon penglai sp. nov. (E-H). A, B NCHUZOOL 15194 (male, 35.4 x 31. 2 mm, Tai-an, Miaoli, northwestern Taiwan) C NCHUZOOL 15211 (male, 24.8 x 22.1 mm, Dongshih, Taichung, western Taiwan) D NCHUZOOL 15181 (male, 28.0 x 23.9 mm, Rihyuetan, Nantou, western Taiwan) E, F NCHUZOOL 15204 (2 males, 39.7 x 34.4 mm, 40.6 x 34.3 mm, Nanrenshan, Pingtung, southern Taiwan) G NCHUZOOL 15224 (paratype male, 36.4 x 30.9 mm, Liyu Lake, Shoufeng, Hualien, eastern Taiwan) H NCHUZOOL 15229 (male, 33.1 x 29.7 mm, Jili Lake, Guangfu, Hualien, eastern Taiwan).

Figure 6. Candidiopotamon penglai sp. nov., holotype male (38.4 x 33.4 mm) from Ji-an, Hualien (NCHUZOOL 12951), G 1 in bent form A left G 1, ventral view B left G 1, dorsal view C left G 1 terminal segment, dorsal view. Scale bars: 1 mm. Arrow indicates the keel-like projection on the distal inner edge of the terminal segment.

Figure 7. Candidiopotamon penglai sp. nov., male (42.9 x 36.2 mm) from Shihzih, Pingtung (NCHUZOOL 15207), G 1 in straight form A left G 1, ventral view B left G 1, dorsal view C left G 1 terminal joint, dorsal view. Scale bars: 1 mm. Arrow indicates the keel-like projection on the distal inner edge of the terminal segment.