Spider Crabs of the Samadinia pulchra complex (Crustacea: Decapoda: Epialtidae) Author Ahyong, Shane T. Australian Museum Research Institute, Australian Museum, 1 William Street, Sydney NSW 2010, and School of Biological, Earth & Environmental Sciences, University of New South Wales, Kensington NSW 2052, Australia Author Lee, Bee Yan Tropical Marine Science Institute, National University of Singapore, 18 Kent Ridge Road, Singapore 119227, Republic of Singapore Author Ng, Peter K. L. Lee Kong Chian Natural History Museum, National University of Singapore, 2 Conservatory Drive, 117377, Republic of Singapore text Records of the Australian Museum 2023 Rec. Aust. Mus. 2023-12-06 75 4 343 356 http://zoobank.org/23801e7a-92aa-4422-9a94-ff37999d28e1 journal article 296058 10.3853/j.2201-4349.75.2023.1876 a09d1777-733f-415f-a151-a2ae3feea4f0 2201-4349 10413992 Samadinia pulchra (Miers in Tizard, Moseley, Buchanan & Murray, 1885 ) Figs 1–3 , 7A, B Amathia ( Amathia ) pulchra Miers in Tizard, Moseley, Buchanan & Murray, 1885: 589 . Anamathia pulchra .— Miers, 1886 : xxix (list), xl, xliii (list), 26–27, pl. IV fig. 1, 1a–c ( type locality: Philippine Islands ). Rochinia pulchra . — Sakai, 1938: 278 (key), 278, 279, text-fig. 35, pl. 37 fig. 4.— Serène & Lohavanijaya, 1973: 55 (key), 56, 57, figs 119–122, pl. 11 A.— Takeda, 1975: 144 , 145, 151 (table), fig. 4a, b.— Sakai, 1976: 223 (key), 223, 224, pl.79 fig. 1.— Griffin, 1976: 210 .— Griffin & Tranter, 1986a: 176 (key), 185, 187.— Griffin & Tranter, 1986b: 363 .— Davie & Short, 1989: 182 .— Ikeda, 1998: 12 (list), 14 (table), 35, pl. 37 figs 1–3.— Muraoka, 1998: 25 .— Takeda, 2001: 241 , 251 (table), 255 (table), 259 (table).—Casadío et al. , 2005: 159 (list).— Ng & Richer de Forges, 2007: 62 (list), 65.— Richer de Forges & Poore, 2008: 66 (list), 68, 69 (in part).— Ng et al. , 2008: 105 (list).— Ng & Richer de Forges, 2013: 362 , fig. 5D.— Richer de Forges & Ng, 2013: 468 , 469, fig. 1C (in part, Philippine material only).— Wang et al. , 2017 : app. 1.— Ng et al. , 2017: 53 (list).— Tavares & Santana, 2018: 223 (list).— Lee et al. , 2019: 35 , 40. Samadinia pulchra .— Lee et al. , 2021: 22 (list), 33, 43 [new combination]. Holotype : NHM 1884.31, male (pcl 19.3 mm , cw 13.0 mm), S of Panglao Island , Bohol Sea , Philippines , 9°26'00"N 123°45'00"E , 375 fm ( 686 m ), dredged, HMS Challenger , stn 210. Other material examined . Japan : USNM 120721 , 3 males (pcl 15.9 mm , cw 9.9 mm to pcl 17.6, cw 11.3 mm ), 2 females (pcl 19.0 mm, cw 12.2 mm ; pcl 18.8 mm , cw 12.5 mm ), Tosa Bay , 33°17.5'N 133°32.88'E , coll. T. Sakai & K. Sakai , February 1966 ; NSMT-Cr 13615 , 6 males (pcl 13.9 mm , cw 9.2 mm to pcl 21.1 mm , cw 14.1 mm ), 2 ovigerous females (pcl 17.5 mm , cw 11.6 mm ; pcl 17.8 mm , cw 12.2 mm ), 1 female (pcl 18.3 mm , cw 12.9 mm ), Tosa Bay , 33°13.5–12.8'N 133°41.6–41.4'E, 440–460 m , K00-8-400, FV Kotaka Maru , 24August 2000 ; SMF , 4 ovigerous females (pcl 15.5 mm , cw 10.2 mm to pcl 17.3 mm , cw 11.2 mm ), Tosa Bay , coll. K. Sakai , 1995; SMF , 1 male (cl 25.9 mm , pcl 16.2 mm , cw 10.7 mm ), 1 ovigerous female (pcl 15.5 mm , cw 10.6 mm ), Haritsunogani , Tosa Bay , TS00433, coll. K. Sakai ; SMF , 1 ovigerous female (pcl 14.1 mm , cw 9.0 mm), 1 female (pcl 13.1 mm , cw 8.8 mm ; with rhizocephalan), Mimase , Kochi , 10 March 1988 ; SMF , 1 male (cl 26.2 mm , pcl 19.0 mm, cw 12.3 mm ), 1 ovigerous female (cl 26.3 mm , pcl 17.3 mm , cw 11.2 mm ), off Kii , 250–350 m , coll. S. Nagai , November 1993 . Taiwan : ZRC , 1 female (cl 29.9 mm , pcl 19.4 mm , cw 12.7 mm ), SE of Kaohsiung , 22°4.2'N 120°10.2'E , 467–634 m , TAIWAN 2000 stn CP19, RV Fishery Researcher 1 , 29 July 2000 . South China Sea : ZRC 1968.2 .13.4, 1 male (cl 26.8 mm , pcl 17.3 mm , cw 11.6 mm ), northern South China Sea , SSE of Hong Kong , cruise 4/64, st. 36, trawl (247), Hong Kong Fisheries Research Station , RV Cape St. Mary ; ZRC 1968.2 .15.4, 1 male (cl 13.2 mm , pcl 8.6 mm ), 135 miles SSE of Hong Kong , 20°05'N 115°03'E , 299–300 fm ( 547–549 m ), cruise no. 4/64 st. 119, trawl (218), Hong Kong Fisheries Research Station , RV Cape St. Mary , coll O. T. Chan , 22 August 1964 ; ZRC 1968.2 .15.3, 1 male (cl 31.1 mm , pcl 17.5 mm , cw 12.4 mm ), SSE of Hong Kong , 394 fm ( 721 m ), cruise 4/64 st. 121, trawl (219), Hong Kong Fisheries Research Station , RV Cape St.Mary , coll O. T. Chan , 22 August 1964 ; ZRC 1968.2.15.5 , 1 ovigerous female (cl 32.9 mm , pcl 19.1 mm , cw 13.5 mm ), northern South China Sea , SSE of Hong Kong , cruise 4/64, trawl (130), Hong Kong Fisheries Research Station , RV Cape St. Mary ; ZRC 2022.0792 , 3 males (cl 24.2 mm , pcl 14.5 mm , cw 9.7 mm to cl 28.7 mm , pcl 17.8 mm , cw 11.6 mm ), 1 female (cl 28.4 mm , pcl 17.4 mm , cw 11.0 mm), 6 ovigerous females (cl 21.7 mm , pcl 13.9 mm , cw 8.8 mm to cl 28.0 mm, pcl 17.4 mm , cw 11.5 mm ), 1 juvenile female (cl 16.7 mm , pcl 10.5 mm , cw 6.3 mm ), Macclesfield Bank , 16°13.60'N 115°01.61'E to 16°11.21'N 114°59.77'E, 526– 510 m , ZHONGSHA 2015 stn CP4155, 28 July 2015 ; ZRC 2022.0793 , 1 male (cl 36.0 mm,pcl 21.4 mm ,cw 14.5 mm ), Macclesfield Bank , 16°13.60'N 115°01.61'E to 16°11.21'N 114°59.77'E, 526– 510 m , ZHONGSHA 2015 stn CP4155, 28 July 2015 ; ZRC 2022.0794 , 5 males (cl 22.3 mm , pcl 13.9 mm , cw 8.5 mm to cl 37.2 mm , pcl 21.2 mm , cw 14.3 mm ),E of Macclesfield Bank , 16°09.80'N 114°58.73'E to 16°12.19'N 115°00.53'E, 511– 510 m , ZHONGSHA 2015 stn CP4156, 28 July 2015 ; ZRC , 1 ovigerous female (cl 25.0 mm, pcl 15.8 mm , cw 11.4 mm ), W of Pratas , 20°44.86–42.28'N 116°08.01–08.01'E, 420–444 m , DONGSHA 2014 stn CP4128, 1 May 2014 ; ZRC 2022.0795 , 1 male (cl 24.0 mm, pcl 14.6 mm , cw 9.2 mm ), 19°53.06–53.03'N 114°21.68–24.74'E, 536– 524 m , ZHONGSHA 2015 CP4137, 23 July 2015 . Philippines : ZRC 2011.1059 , 1 male (pcl 13.3 mm , cw 7.9 mm ), NE of Luzon , 18°47.49'N 123°08.26'E , 507–540 m , AURORA 2007 stn CP2678, 23 May 2007 ; ZRC 2011.1052 , 1 male (cl 26.4 mm , pcl 16.5 mm , cw 10.5 mm ), 1 female (cl 19.6 mm , pcl 12.4 mm , cw 7.7 mm ), 1 juvenile female (cl 16.9 mm , pcl 11.6 mm , cw 7.2 mm ), off eastern Luzon , 15°59.07'N 121°49.22'E , 496– 364 m , AURORA 2007 stn CC2745 , 2 June 2007 ; ZRC 2011.1043 , 1 male (cl 28.0 mm, pcl 17.9 mm , cw 12.6 mm ), 1 female (cl 23.7 mm , pcl 15.0 mm, cw 9.9 mm ), off eastern Luzon , 15°58.78–56.63'N 121°46.44–44.85'E, 182–220 m , AURORA 2007 stn CC2746 , 2 June 2007 ; ZRC 2011.1049 , 1 damaged male, 1 ovigerous female (pcl 15.7 mm , cw 9.6 mm ), off eastern Luzon , 15°58.03'N 121°49.11'E , 422–431 m ,AURORA 2007 stn CP 2658, 20 May 2007 ; ZRC 2011.1053 , 1 male (cl 20.0 mm, pcl 12.5 mm , cw 7.5 mm ), 1 ovigerous female (cl 18.7 mm , pcl 12.2 mm , cw 7.6 mm ), 1 female (cl 24.6 mm , pcl 15.6 mm , cw 9.8 mm ), 3 juvenile females (cl 16.6 mm , pcl 11.5 mm , cw 6.9 mm to cl 20.4 mm , pcl 13.0 mm, cw 8.0 mm), off eastern Luzon , 15°56.41'N 121°48.88'E , 460–480 m , AURORA 2007 stn CP2659, 20 May 2007 ; ZRC 2013.0629 , 1 ovigerous female (cl 23.0 mm, pcl 15.2 mm , cw 10.3 mm ), off eastern Luzon , 15°07.61'N 121°36.95'E , 309 m , AURORA 2007 stn CP2708, 28 May 2007 ; USNM 49498 , 1 ovigerous female (not measured), Verde Island Passage, 13°53'00"N 120°26'45"E , 454 m , Albatross stn 5282, 18 July 1908 ; USNM 49497 , 1 male (not measured), Verde Island Passage , 13°48'30"N 120°28'40"E , 512 m , dark grey silt, Albatross stn 5283, 18 July 1908 ; USNM 49499 , 1 male (not measured), Sibuyan Sea , SE Luzon , 13°17'45"N 122°22'00"E , 723 m , soft green mud, Albatross stn 5378, 4 March 1909 ; USNM 49495 , 1 male (not measured), 1 female (not measured), Tablas Strait , E of Mindoro , 13°12'45"N 121°38'45"E , 518 m , green mud, Albatross stn 5123, 2 February 1908 ; USNM 49500 , 1 female (not measured), Tablas Strait , SE of Mindoro , 12°25'35"N 121°31'35"E , 428 m , Albatross stn 5260, 3 June 1908 ; USNM 49494 , 1 male (not measured), NW of Batag Island , Philippine Sea , 12°43'51"N 124°58'50"E , 564 m , green mud, Albatross stn 5444, 3 June 1909 ; ZRC , 2 females (cl 26.6 mm , pcl 16.2 mm , cw 11.2 mm ; cl 25.5 mm , pcl 16.8 mm , cw 11.4 mm ), same; ZRC , 1 male (cl 19.0 mm, pcl 13.3 mm , cw 9.1 mm ), 1 ovigerous female (cl 25.0 mm,pcl 16.6 mm , cw12.0 mm), S of Bohol , Bohol Sea , 9°31.4'N 124°00.6'E , 738–798 m , PANGLAO 2005 stn CP2350, 24 May 2005 ; USNM 49492 , 1 ovigerous female (pcl 19.9 mm , cw 13.3 mm ), between Siquijor and Bohol , 5.8 miles SW of Balicasag Island , Bohol Sea , 9°24'45"N 123°39'15"E , 503 m , globigerina ooze, Albatross stn 5528, 11 August 1909 ; USNM 49493 , 2 males (not measured), between Panglao Island and Siquijor Island , Bohol Sea , 9°22'30"N 123°42'40"E , 717 m , globigerina ooze, Albatross stn 5527, 11August 1909 ; ZRC , 1 ovigerous female (cl 27.5 mm , pcl 17.0 mm,cw 12.0 mm), S of Siquijor , Bohol Sea , 8°53.1'N 123°33.5'E , 516–543 m ,PANGLAO 2005 stn CP2361, 26 May 2005 ; MNHN , 1 female (cl 43.2 mm , pcl 27.9 mm , cw 10.4 mm ), Balicasag Island , Bohol Sea , 8°52.1'N 123°37.1'E , 569–583 m , PANGLAO 2005 stn CP2358, 26 May 2005 ; AM P.90365, 1 female (with rhizocephalan; pcl 16.4 mm , cw 11.3 mm ), same; ZRC 2013.0623 , 2 juvenile females (cl 19.9 mm , pcl 12.3 mm , cw 8.2 mm ; cl 20.8 mm , pcl 12.7 mm , cw 8.4 mm ), same; NMCR , 1 male (cl 34.5 mm , pcl 19.5 mm , cw 12.9 mm ), NE of Aligbay Island , Sulu Sea , 8°46.2'N 123°16.1'E , 624–647 m , PANGLAO 2005 stn CP2384, 29 May 2005 ; USNM 49496 , 1 male (not measured), Iligan Bay , Mindanao , 8°16'45"N 124°02'48"E , 924 m , grey mud, fine silt, Albatross stn 5513, 7 August 1908 . Diagnosis . Carapace with at least 20 sharp, slender, upright dorsal spines (paired preorbital; paired hepatic; 6 gastric; 1 median cardiac; 1 median intestinal; on each side, 4 pairs branchial); hepatic spine with lateral surface flattened or weakly sulcate. G1 distal margin oblique, straight to irregularly gently sinuous. Description (specimens> 10 mm pcl). Carapace pyriform, pcl 1.4–1.7× width, regions weakly defined, entire surface with tomentum of short lobular setae. Rostral spines usually strongly divergent for entire length (occasionally weakly divergent to subparallel), straight to outwardly curved (in dorsal view), straight to curved but slightly upcurved in lateral view; length 0.4–0.8× pcl; margins lined with short, soft, lobular setae and scattered simple setae. Dorsal orbital eave weakly expanded, produced as a long, slender upright spine, inclined anteriorly and usually slightly incurved; postorbital lobe short, anteriorly cupped; hiatus wide, U-shaped. Dorsal surface with long, slender, upright spines in following pattern: straight, near vertical hepatic spine with lateral surface flattened or weakly sulcate; gastric region with 6 slender upright spines ( 2 in midline; paired epigastric and protogastric spines) and usually with two shorter spines or tubercles in transverse row between anterior and posterior median spines; cardiac and intestinal regions each with straight, upright spine; branchial regions each with 4 straight, upright, spines, 2 near lateral carapace margin and directed laterodorsally, 2 on upper surface, almost vertical. Pterygostomial region with 3 or 4 tubercles in longitudinal row below moult suture, followed by tubercle on anterior branchial submargin slightly below moult suture. Eyestalks short, sparsely setose anteriorly, cornea terminal. Basal antennal article length about twice width; surface shallowly sulcate longitudinally; anterolateral angle blunt, weakly produced to small spine, visible in dorsal view; lateral margin lateral margin concave, not expanded under eyestalk; prominent tubercle situated between antennal gland and margin of ventral orbital hiatus. Figure 2 . Samadinia pulchra (Miers in Tizard, Moseley, Buchanan & Murray, 1885 ), holotype male (pcl 19.3 mm, cw 13.0 mm), Philippines, NHM 1884.31. ( A ) dorsal; habitus; ( B ) thoracic sternum and pleon; ( C ) ventral anterior cephalothorax; ( D ) carapace, right lateral view. Figure 3 . Samadinia pulchra (Miers in Tizard, Moseley, Buchanan & Murray, 1885 ). ( A ) male (pcl 12.5 mm, cw 7.5 mm), Philippines, CP2659, ZRC 2011.1053; ( B ) male (pcl 19.5 mm, cw 12.9 mm), Philippines, CP2384, NMCR; ( C ) male (pcl 21.4 mm, cw 14.5 mm), Macclesfield Bank, CP4155, ZRC. Image credits: Tin-Yam Chan. Maxilliped 3 unarmed, merus subtriangular, anterolateral angle weakly produced, apex rounded, slightly wider than ischium; ischium subquadrate, outer surface with shallow longitudinal depression. Cheliped (pereopod 1) length 1.2–2.1 (usually> 1.3) × pcl (male), 0.8–1.3 × pcl (usually <1.2) (female); merus slightly shorter than propodus, extensor margin with proximal tubercle and small distal spine, flexor margin with 2 or 3 low, widely spaced tubercles; carpus shorter than dactylus, unarmed, although large adult males with dorsal and mesial ridge; propodus smooth, laterally compressed, dorsally cristate and more robust in adult males, palm length 1.8–3.0 × height (male), 2.6–3.4 × height (female); dactylus and pollex equal, length 0.6–0.8 × palm length (male), 0.7–0.9 × palm length (female); occlusal margins crenulate, proximal gape slight in males, absent in females. Ambulatory legs (P2–5) slender, subcylindrical in cross-section, sparsely covered with short simple setae and short, club-like setae; merus extensor margin with short distal spine, sometimes indistinct on P5; dactyli unarmed, covered with short setae, apex corneous. Pereopod 2 length 2.2–3.0 (usually> 2.5) × pcl (male), 1.5–2.8 × pcl (usually <2.5) (female); merus 0.8–1.2 × pcl (usually> 1.0) (male), 0.5–1.1 (usually <0.9) (female). Pereopod 5 length 1.4–1.8 × pcl (male), 0.9–1.8 × pcl (female); merus 0.5–0.6 × pcl (male), 0.3–0.6 × pcl (female). Pleon with 6 free somites and telson, unarmed; widest at somites 2 and 3 in males, at somites 5 and 6 in females; surface covered with short bulbous setae. Male telson triangular to linguiform, as long as wide, margins straight, apex rounded. G1 straight, flattened; distally expanded, distolaterally produced to acute triangular point, distomesially forming low blunt lobe or obtuse angled; distal margin oblique, straight to irregularly gently sinuous. G2 simple, about ¼ length of G1; endopod absent. Colour in life . Juveniles and small adults with carapace and pereopods overall creamy-white; rostral spines and anterior carapace spines dull orange; dorsal carapace spines distally diffusely dull orange; cheliped fingers pale pinkish ( Fig. 3A ). Largest specimens with pereopods dull pinkish-pale orange, carapace pale white to pale pinkish-orange centrally ( Fig. 3B, C ). Remarks . Samadinia pulchra was described by Miers (in Tizard, Moseley, Buchanan & Murray, 1885 ) (see also Miers, 1886 ) from single male specimen collected off the Philippines . The species has since been widely reported in the Indo-West Pacific (e.g., Griffin & Tranter, 1986a ; Richer de Forges & Ng, 2013 ). Although previously thought wide-ranging in the Indo-West Pacific, present results show that S . pulchra sensu stricto is restricted to the western Pacific from Japan and Taiwan to the South China Sea including the Philippines ( Fig. 1 ). Previous records of S . pulchra from the Indian Ocean are referrable to S . livermorii (Western Indian Ocean to Andaman Sea and southwestern Indonesia ) and S . jimlowryi sp. nov. (southeastern Indonesia to northwestern Australia ). Of these, S. pulchra is most similar to S . livermorii , sharing similar G1 morphology and straight dorsal carapace spines, differing in the laterally flattened hepatic spine (versus conical or cylindrical). Samadinia pulchra agrees with S . jimlowryi in the flattened to weakly sulcate lateral surface of the hepatic spine of the carapace ( Figs 2D , 4C ) but differs by the simple G1 distal margin (versus bilobate) ( Figs 7A, B, C, E ), and straight, shorter dorsal carapace spines (prominently longer, anteriorly recurved in S . jimlowryi ; Figs 2D , 3 , 4 ) (see Remarks for S . livermorii ). As in its congeners, carapace spine length varies allometrically in S . pulchra , albeit attaining proportionally shorter lengths than in S . jimlowryi (see Remarks for that species). Sexual dimorphism in cheliped robustness and more elongate walking legs in S . pulchra is marked, being most evident in males 16 mm pcl and larger ( Figs 2A , 3C ). Females are mature by 12–15 mm with the smallest ovigerous female (pcl 12.2 mm ; ZRC 2011.1053). Apart from sexual dimorphism and normal allometric changes, variation is primarily evident in rostral form, ranging from straight (the usual condition) to outwardly curved ( Figs 2A , 3 ). The pair of tubercles or low spines, usually present in a transverse row across the gastric region ( Fig. 3C ), may be absent or represented on one side only. Distribution . Western Pacific, from Japan and Taiwan to the South China Sea (including Macclesfield Bank and Hong Kong ) to the southern Philippines ( Fig. 1 ); 95–924 m (usually 500–600 m ) ( Takeda, 2001 ; present results).