Scandarma lintou Schubart, Liu and Cuesta, 2003

Naruse, Tohru & Ng, Peter K. L., 2020, Revision of the sesarmid crab genera Labuanium Serène and Soh, 1970, Scandarma Schubart, Liu and Cuesta, 2003 and Namlacium Serène and Soh, 1970 (Crustacea: Decapoda: Brachyura: Sesarmidae), with descriptions of four new genera and two new species, Journal of Natural History (J. Nat. Hist.) 54 (7 - 8), pp. 445-532 : 476-480

Scandarma lintou Schubart, Liu and Cuesta, 2003

( Figures 15–17 )

Scandarma lintou Schubart, Liu and Cuesta, 2003, p. 49 , figs 1–8 [type locality: Green Island, Taiwan]; Naruse and Ng 2007, p. 337; Ng et al. 2008a, p. 223; Lin et al. 2011, p. 49; Maenosono and Naruse 2011, p. 49, figs 1, 2; Li and Chiu 2013, p. 55; Okuyama 2014, p. 119, fig. 1A; Maenosono 2017a, p. 321; Ng et al. 2017, p. 107, fig. 11e.

Material examined

Paratypes. ZRC 2001.0026 , 1 female, 17.8 × 18.6 mm, 1 ovig. female, 16.3 × 17.7 mm, Kangkou River mouth, Manchow, Pingtung County, Taiwan, coll. P.K.L. Ng, 8 November 2000; ZRC 2002.0168 , 1 male, 19.0 × 19.6 mm, same locality as ZRC 2001.0026, coll. H.-C. Liu, 17 June 2001 .

Others. ZRC 2002.0169 , 1 male, 18.1 × 18.3 mm, Mei-Lun River mouth, Hualien, Taiwan, coll. H.-C. Liu, 17 June 2001; ZRC 2002.0168 , 1 male, 18.9 × 19.3 mm, Mei Lun River mouth, Hualien, Taiwan, coll. H.-C. Liu, 17 June 2001. ZRC 2002.0165 , 1 male, 13.3 × 13.5 mm, 1 ovig. female, 17.3 × 18.1 mm, Mei-Lun River mouth, Hualien, Taiwan, coll. H.-C. Liu, 17 June 2001; ZRC 2017.0986 , 1 male, on Pandanus, Niu Shan , Hualien City, Hualien, Taiwan, coll. J.-J. Li and P.Y.C. Ng, 14 June 2017; ZRC 2017.0987 , 2 males, on Pandanus, Mei Lun River , Hualien City , Hualien, Taiwan, coll. J.-J. Li and P.Y.C. Ng, 14 June 2017; ZRC 2000.1830 , 1 male, 16.5 × 16.8 mm, Gangkou River mouth, Kenting National Park, Pingtung, Taiwan, coll. C.D. Schubart, H.-C. Liu et al., 14 September 1999; ZRC 2001.0026 , 1 male, 15.8 × 16.2 mm, 2 females, 16.5 × 17.3 mm, 17.9 × 18.4 mm, Chia-Le-Shui, Gang Kou River , Kenting National Park, Pingtung, Taiwan,coll.P. K.L. Ng, 8 November 2000; ZRC 2001.0027 , 1 juvenile male, 8.2 × 8.2 mm, Chia-Le-Shui, Gang Kou River , Kenting National Park, Pingtung, Taiwan, coll. P.K.L. Ng, 8 November 2000; ZRC 2002.0164 , 1 male, 14.9 × 15.0 mm, 1 female 16.0 × 16.7 mm, Hsiang-Chiao-Wan, Kenting National Park , Pingtung, Taiwan, coll. H.-C. Liu, 20 June 2001; RUMF-ZC-1392, 1 male, 16.5 × 16.8 mm, Oura River , Okinawa Island, Ryukyu Islands, Japan, coll. T. Maenosono, 4 June 2010; RUMF-ZC-2024, 2 females, 12.9 × 13.6, 17.1 × 18.3 mm, near Geda River , Iriomote Island, Ryukyu Islands, Japan, coll. T. Naruse, 30 June 2012. ZRC, 2 males, 9.1 × 10.2, 13.2 × 14.1 mm, Ambon, Indonesia, coll. H.H. Tan, 12–20 August 2012.

Diagnosis

Carapace squarish, lateral margins almost parallel, external orbital angle sharply pointed; 2 pairs of postfrontal lobes present, lateral lobes slightly exceeding mesial lobes anteriorly in large individuals ( Figure 15 (a)), anterior edges of all lobes relatively close to but never reaching frontal margin in dorsal view. Palm ( Figure 16 (a,c)) of male chela swollen, outer surface granulated, granules smaller on lower part, distally sloping smooth area around bases of fingers, proximally bearing large median protuberance; upper surface ( Figure 16 (c)) with 1 straight, longitudinally traversing row of small granules, and with several short, oblique rows of granules inner side. Immovable finger ( Figure 16 (a)) slightly curved upwards, gradually tapering towards tip; occlusal margin lined with elevation over proximal third (6–7 teeth on elevation, distal one largest), followed distally by entire margin or a few smaller teeth, distal quarter with 2 large teeth; lower margin irregularly lined with small teeth. Movable finger ( Figure 16 (a)) strongly curved downwards; occlusal margin lined with 2–3 proximal teeth, followed distally by entire margin or small teeth, and subdistal 1 large tooth; inner side of upper margin regularly lined with flat, rounded granules, granules becoming smaller proximally and distally. Subdistal tooth of movable finger fitting between 2 subdistal teeth of immovable finger when closed. Male pleonal somite 3 widest, lateral margins of somites 3–6 forming gradually narrowing curvature. G1 short, almost straight, stout, narrowed medially; distal end with anterolaterally directed wide corneous process. Vulvae on distal three-fifths of sternite 6, anterior margin adjacent to thoracic sternal suture 5/6, ellipsoidal, margin rimmed except for posteromesial corner, mesial end of posterior rim produced to wide, short triangular lobe, double-rimmed anteromesially, sternal vulval cover developed from anterolateral margin, covering almost entire vulva, except for slit-like gap on posteromesial corner, cover produced ventrally as earlobe-like structure.

Variation

Small individuals have all the postfrontal lobes aligned anteriorly, with the lobes close to but never reaching frontal margin in dorsal view (e.g. CW 13.6 mm) ( Figure 17 (a)).

Colouration

In life, carapace dorsal surface with yellowish-brown ground colour and finely mottled with black patches, epigastric to mesogastric regions with slightly paler inverted triangle; posterolateral margins yellow, inside of these margins with black, horizontally short triangles. Chelipeds yellowish from basis to merus; upper surface of carpus to outer surface of palm dark orange; fingers almost whitish, except for dark orange proximal part of movable finger. See Schubart et al. (2003, p. 52, fig. 5); Maenosono and Naruse (2011, p. 52, fig. 1A); Ng et al. (2017, fig. 11e).

Distribution

Western Pacific: Okinawa and Iriomote Islands, Ryukyu Islands, Japan ( Maenosono and Naruse 2011; Maenosono 2017a); Green Island [type locality] and southern Taiwan ( Schubart et al. 2003); Divilacan, north-east Luzon Island, Philippines ( Okuyama 2014); Ambon, Indonesia (present study).

Remarks

Scandarma lintou is morphologically most similar to Sc. gracilipes in the structures of the G1 and vulva. However, the two species can be distinguished from each other by the relative length of their ambulatory legs. The P4 merus is proportionally longer in Sc. lintou than in Sc. gracilipes ( Figure 18 ).

Two small, immature male specimens from Ambon, Indonesia, are tentatively identified as Sc. lintou for now. The identity of the Ambon specimens should be verified when adult specimens become available for examination.

Ecological note

Schubart et al. (2003, p. 53) listed three environmental factors on the habitat of Scandarma lintou : ‘1) the close proximity of a stream or freshwater pools, 2) protection from strong winds, and 3) the presence of the screw pine or pandang Pandanus odoratissimus ( Pandanales : Pandanaceae )’. This species can be observed more commonly at night on Pandanus trees as well other trees around them, and also on relatively low vegetation within coastal forests. See Schubart et al. (2003, p. 53) and Maenosono and Naruse (2011, p. 52, fig. 1B).

Figures

Figure 15. Scandarma lintou Schubart, Liu and Cuesta, 2003. Paratype, ZRC 2002.0168, male, 19.0 × 19.6 mm (Taiwan). a, habitus, dorsal view; b, anterior part of cephalothorax, anteroventral view.

Figure 16. Scandarma lintou Schubart, Liu and Cuesta, 2003. Paratype, ZRC 2002.0168, male, 19.0 × 19.6 mm (Taiwan). a–c, left chela; a, outer view; b, inner view; c, upper view; d, meri of right P4 and P5.

Figure 17. Dorsal view of carapace of small individuals of Scandarma species. a, Sc. lintou, RUMF-ZC -2024, female, 12.9 × 13.6 mm; b, Sc. gracilipes, RUMF-ZC-5014, female,11.2 × 12.0 mm; c, Sc. papua, NHM 1922.11.9.2–5, female, 11.3 × 12.8 mm.

Figure 18. Correlationship between merus length of P4 (third ambulatory leg) against carapace length of Scandarma lintou Schubart, Liu and Cuesta, 2003, Sc. gracilipes (H. Milne Edwards, 1853) and Sc. papua sp. nov.