Hermit crabs of the genera Calcinus Dana, Clibanarius Dana, and Dardanus Paul’son from the PANGLAO 2004 Expedition, with description of a new species and a checklist of the hermit crabs of the Philippines (Crustacea: Anomura: Paguroidea) Author Malay, Maria Celia (Machel) D. Author Rahayu, Dwi Listyo Author Chan, Tin-Yam text Raffles Bulletin of Zoology 2018 2018-01-17 66 23 65 journal article 6557 10.5281/zenodo.4503028 479d8c3b-8194-4f81-bed5-d157d5aa021e 2345-7600 4503028 C0EDB2F2-78E4-43A0-A8C4-E4165DF6406F Dardanus lagopodes ( Forskål, 1775 ) ( Figs. 3H , 5 A–B) Cancer lagopodes Forskål, 1775: 93 (Red Sea, type locality). Pagurus sanguinolentus – Forest, 1953b: 559–560 , Figs. 12–14 [in part]; Fize & Serène, 1955: 166–173 , Fig. 25, pl. 4 nos. 4–5 [in part] (not Pagurus sanguinolentus Quoy & Gaimard, 1824 ). Pagurus affinis H. Milne Edwards, 1836: 274 ( Sri Lanka , type locality). Pagurus euopsis Dana, 1852: 452–453 (Upolu, Samoa , type locality); Estampador, 1937: 503 (in part). Dardanus lagopodes – Lewinsohn, 1969: 32 , Fig. 1–2 pl. 2 [in part]; Ball & Haig, 1972: 92–93 [in part]; Haig & Ball, 1988: 166 ; McLaughlin et al., 2007: 91–93, 3 unlabelled figures [in part]. Material examined. 1 male SL 7.8 mm ( ZRC ), stn B1, Alona Reef , Panglao I. , 9°33.0′N , 123°46.5′E , 8–14 m , 30.v.2004 ; 2 males SL 4.4–5.6 mm ( ZRC ), stn B3, Arco Point , Panglao I. , 9°33.5′N , 123°48.6′E , 8 m , 31.v.2004 ; 1 male SL 9.0 mm ( ZRC ), stn B7, Catarman , Panglao I. , 9°35.9′N , 123°51.8′E , 4–30 m , 5.vi.2004 ; 1 ovig. female SL 2.9 mm , 1 male SL 3.9 mm ( ZRC ), stn B9, Napaling , Panglao I. , 9°33.1′N , 123°44.0′E , 8.5–10 m , 8.vi.2004 ; 1 female SL 10.1 mm , 1 male SL 11.1 mm ( ZRC ), stn M1, Alona Beach , Panglao I. , 9°32.9′N , 123°46.6′E , 0–1 m , v.2004 to vii.2004 ; 2 males SL 7.8–9.8 mm ( ZRC ), stn M2, west end of Alona Beach , Panglao I. , 9°32.8′N , 123°45.9′E , 0–2 m , 30.v.2004 ; 2 males SL 10.3–12.8 mm ( ZRC ), stn M7, Momo Beach, Panglao I., 9°36.1′N , 123°45.2′E , 0–3 m , 1.vi.2004 ; 1 female SL 6.6 mm ( ZRC ), stn M8, Doljo , north coast, Panglao I. , 9°35.4′N , 123°44.3′E , 0–1 m , 2.vi.2004 ; 1 male SL 11.2 mm ( ZRC ), stn M18, Gak-Ang Islet , off Panglao I. , 9°33.0′N , 123°45.5′E , 0–1 m , 10 & 12.vi.2004 ; 1 male SL 14.0 mm ( ZRC ), stn M19, Pamilacan I., 9°30.0′N , 123°55.3′E , 0–2 m , 11.vi.2004 ; 1 ovig. female SL 9.1 mm , 1 female SL 7.3 mm , 1 male SL 8.0 mm ( ZRC ), stn M58, Balicasag I., 9°31.3′N , 123°41.0′E , depth unknown, 4.vii.2004 ; 2 males SL 8.0– 9.8 mm ( ZRC ), stn N2, Alona Reef , Panglao I. , 9°32.9′N , 123°46.6′E , 12 m , 7.vi.2004 ; 1 male SL 7.2 mm ( ZRC ), stn N4, Alona Reef , Panglao I. , 9°32.9′N , 123°46.9′E , 15–20 m , 10.vi.2004 ; 1 female SL 6.9 mm , 3 males SL 7.4–12.6 mm ( ZRC ), stn R1, Balicasag I., 9°31.2′N , 123°41.3′E , 5–7 m , 30.v.2004 ; 1 male SL 7.8 mm ( ZRC ), stn R3, Alona Reef , Panglao I. , 9°33.0′N , 123°46.5′E , 5–24 m , v.2004 to vii.2004 ; 1 male SL 7.5 mm ( ZRC ), stn R5, Catarman , Panglao I. , 9°36.6′N , 123°52.4′E , 5–16 m , 31.v.2004 ; 1 female SL 8.3 mm , 2 males SL 10.4–11.5 mm ( ZRC ), stn R6, Baclayon , Bohol I., Loay , Bohol I., 9°36.6′N , 123°57.8′E , 5–12 m , 31.v.2004 ; 1 female SL 7.2 mm ( ZRC ), stn R8, House Reef , Panglao I. , 9°31.2′N , 123°41.3′E , 4–24 m , v.2004 to vii.2004 ; 1 ovig. female SL 7.0 mm, 2 males SL 7.3–9.4 mm ( ZRC ), stn R10, Biking , Panglao I. , 9°35.3′N , 123°50.5′E , 2–10 m , 1.vi.2004 ; 1 female SL 8.7 mm , 1 male SL 9.5 mm ( ZRC ), stn R11, Biking , Panglao I. , 9°35.2′N , 123°50.5′E , 4 m , 2.vi.2004 ; 1 female SL 10.2 mm , 1 male SL 9.0 mm ( ZRC ), stn R13, Doljo Point , Panglao I. , 9°35.6′N , 123°43.2′E , 2–41 m , 2.vi.2004 ; 2 females SL 9.5–12.0 mm, 1 male SL 14.1 mm ( ZRC ), stn R14, Baclayon , Bohol I., 9°37.4′N , 123°54.5′E , 6–8 m , 3.vi.2004 ; 1 male SL 10.3 mm ( ZRC ), stn R15, Arco Point , Panglao I. , 9°33.5′N , 123°48.6′E , 6–30 m , 3.vi.2004 ; 2 males SL 7.2–8.9 mm ( ZRC ), stn R17, Black Forest , Panglao I. , 9°31.1′N , 123°41.3′E , 3–15 m , 4.vi.2004 ; 3 males SL 3.8–9.5 mm ( ZRC ), stn R20, Cathedral , 9°31.1′N , 123°41.5′E , 7–48 m , 5.vi.2004 ; 1 male SL 9.6 mm ( ZRC ), stn R23, lagoon off Poblacion , Panglao I. , 9°33.5′/34.8′N, 123°42.7′/46.3′E, 1–5 m , 5, 6, & 21.vi.2004 ; 1 female SL 3.8 mm ( ZRC ), stn R24, Bingag , Panglao I. , 9°37.5′N , 123°46.8′E , 0–2 m , 6.vi.2004 ; 1 female SL 6.7 mm , 1 male SL 6.5 mm ( ZRC ), stn R27, Napaling , Panglao I. , 9°37.0′N , 123°46.3′E , 2–20 m , 7.vi.2004 ; 1 female SL 11.5 mm ( ZRC ), stn R28, Napaling , Panglao I. , 9°37.0′N , 123°46.3′E , 20–54 m , 7.vi.2004 ; 2 males SL 6.3–8.0 mm ( ZRC ), stn R36, Pamilacan I., 9°30.2′N , 123°55.3′E , 3–32 m , 9.vi.2004 ; 1 male SL 13.3 mm ( ZRC ), stn R38, Pamilacan I., 9°29.4′N , 123°56.0′E , 6–37 m , 11.vi.2004 ; 1 ovig. female SL 5.5 mm , 1 female SL 8.6 mm , 2 males SL 11.4–12.5 mm ( ZRC ), stn R38, Pamilacan I., 9°29.4′N , 123°56.0′E , 6–37 m , 11.vi.2004 ; 1 ovig. female SL 7.5 mm ( ZRC ), stn R42, Baclayon Takot , Bohol I., 9°37.1′N , 123°52.6′E , 8–22 m , 12.vi.2004 ; 3 ovig. females SL 6.5–12.0 mm, 4 males SL 5.5–13.0 mm ( ZRC ), stn R43, Cortes Takot , Bohol I., 9°41.3′N , 123°49.5′E , 3–41 m , 13.vi.2004 ; 1 ovig. female SL 6.5 mm , 1 male SL 9.5 mm ( ZRC ), stn R48, Bingag , Panglao I. , 9°37.6′N , 123°47.3′E , 4–20 m , 17.vi.2004 ; 1 ovig. female SL 6.5 mm , 1 male SL 8.5 mm ( ZRC ), stn R58, Looc (lagoon side), Panglao I. , 9°35.7′N , 123°44.7′E , 1–3 m , 22.vi.2004 ; 2 females SL 6.7–10.1 mm , 2 males SL 6.2–7.4 mm ( ZRC ), stn R73, Balicasag I., 9°30.9′N , 123°40.8′E , 2–30 m , 2.vii.2004 ; 2 males SL 7.1–10.8 mm ( ZRC ), stn R75, west of Pontod , Panglao I. , 9°32.8′N , 123°42.1′E , 3–35 m , 3.vii.2004 ; 1 female SL 7.9 mm , 1 male SL 10.0 mm ( ZRC ), stn R76, lagoon, 9°N , 123°E , 5.vii.2004 ; 2 ovig. females SL 6.9–7.2 mm ( ZRC ), stn R77, between Momo and Napaling , Panglao I. , 9°37.0′N , 123°46.0′E , 2–10 m , 6.vii.2004 . Other material: Dardanus affinis (H. Milne Edwards, 1836 ) holotype , male SL 23 mm ( MNHN Pg. 1305), Ceylon ( Sri Lanka ) . Description. Shield nearly as long as it is wide; anterior margin between rostrum and lateral projections shallowly concave; lateral margins slightly convex, slightly irregular, with tufts of long setae. Posterior margin rounded. Dorsal surface of shield somewhat inflated, with tufts of long setae, strongly calcified; Y-shaped line present posteriorly. Rostral lobe weakly produced. Lateral projections large, bluntly triangular, produced. Posterior carapace lateral elements well calcified, unarmed. Branchiostegites unarmed. Ocular peduncles 0.8–0.9 times length of shield, subcylindrical, somewhat inflated distally, diameter of corneas 0.2 length of ocular peduncles. Ocular acicles broad, distal margins each with 3 spines, with fringe of setae along distal margins. Interocular plate with pair of protrusions. Antennular peduncles slender, when fully extended, distal ultimate segments reaching base of corneas; ultimate and penultimate segments unarmed, basal segment distal margin with tufts of long setae. Antennal peduncles, when fully extended, reaching 0.7 length of ocular peduncles; fifth segment unarmed, with 3–4 scattered setae on dorsal and ventral surfaces; fourth segment with tufts of setae on mesiodistal margin; third segment with tufts of long setae on ventral surface; second segment with dorsolateral distal angle produced, terminating in strong simple spine, lateral margin unarmed, dorsomesial distal angle bearing 1 spine, mesial margin, lateral margin, and dorsolateral distal angle with tufts of setae; first segment unarmed. Antennal acicle short, barely passing base of fourth segment and terminating in strong bifid spine; dorsomesial margin with 3 spines, dorsolateral margin unarmed or with single spine. Antennal flagella bearing minute seta on each articulation. Third maxilliped with well developed crista dentata; basis with 2 small corneous spines. Chelipeds unequal, left larger than right. Left cheliped stout. Outer face of palm, dactyl, and fixed finger convex; bearing rows of corneous-tipped conical spines; with tufts of long and short setae, not concealing armature. Dactyl and fixed finger each terminating in strong corneous claw, cutting edges each with 5–6 (dactyl) or 7–9 (fixed finger) low, molar-like calcareous teeth. Upper margin of palm and dactyl with row of corneous-tipped conical spines, spines larger in upper proximal angle; lower margin bearing row of conical corneous tipped spines. Inner face of dactyl smooth but with row of tufts of setae, inner face of fixed finger with irregular rows of low corneous-tipped spines distally and tufs of setae; inner face of palm with tufts of setae. Carpus with upper margin bearing 2 prominent corneous-tipped spines and 2 smaller spines proximally; outer face with irregular rows of corneous-tipped spines distally, remaining of surface with sparse corneous-tipped spines and tufts of setae, lower outer margin with 1strong corneous-tipped spines; inner face with scattered tufts of setae. Merus with distal margin bearing row of corneous-tipped spines; ventral margin with row of corneous-tipped spines, more prominent spines distally; lateral face with tufts of long setae; ischium with 4 teeth on ventromesial margin. Right cheliped smaller and more slender than left, armament similar. Second pereopods and right third pereopod generally similar; second pair more slender than right third. Dactyls 1.3–1.4 length of propodi; each terminating in strong corneous claw; subcylindrical; ventral margins each with 5–7 small corneous spines distally; dorsal margins each with row of corneous spines; spines obscured by tufts of setae; lateral and mesial surfaces with rows of tufts of setae. Propodi 1.3 length of carpi; dorsal margins each with row of corneous spines obscured by tufts of setae; lateral faces convex, unarmed, and with rows of tufts of setae; ventral margins unarmed but with row of tufts of setae; mesial faces flattened, smooth, unarmed, with rows of tufts of setae. Carpi 0.6–0.7 length of meri; lateral faces flattened with tufts of setae on dorsal and ventral margins; dorsal surfaces covered with tufts of long setae, each bearing two prominent corneous-tipped conical spine distally; distal margins of lateral faces each with row of small, corneous-tipped spines obscured by tufs of setae. Meri lateral faces flattened or slightly convex, with tufts of setae on dorsal and ventral margins; ventral margins each with row of small spines obscured by tufts of seta; dorsal margins each with row of tufts of setae. Ischia unarmed. Left third pereopod stout. Dactyl 1.6 length of propodus, terminating in large corneous claw; dorsal, ventral margins, and lateral face with rows of corneous spines and tufts of short and long setae, mesial face with 3 corneous spines distally and rows of tufts of setae on entire surface. Propodus 1.3 length of carpus, 2.3–2.4 as long as broad; dorsal margin with row of corneous spines obscured by tufts of setae; lateral face convex or flattened, with irregular rows of corneous spines obscured by tufts of short and long setae; ventral margin with row of sometimes bi-spinous corneoustipped spines, obscured by tufts of setae. Carpus 0.8 length of merus; lateral face flattened; dorsal margin with row of corneous-tipped spines; dorsolateral angle with several strong corneous-tipped spines covered by dense tufts of long setae; dorsal, distal, and ventral margins covsered by dense tufts of setae; mesial face slightly convex, smooth, unarmed, distal margin bearing tufts of long setae. Merus lateral face convex, with tufts of long setae on the dorsal, ventral, and subdistal margins; mesial face flattened with tufts of setae on subdorsal margin; ventral margin crested with row of tubercles bearing dense tufts of long setae and 2 calcareous teeth distally. Ischium unarmed. Sternite of third pereopods with anterior lobe rectangular, with 2 protrusions each bearing tuft of long setae anteriorly. Fourth pereopods semichelate; dactyls with 5 corneous ventral spines on lateral face; propodal rasps well developed; carpi each with sharp dorsodistal spine covered by dense tuft of long setae. Fig. 4. A, Dardanus sanguinolentus ( Quoy & Gaimard, 1824 ) . Female ovig. SL 6.3 mm, stn R6; B, Dardanus balhibuon , n. sp. Holotype female SL 14.3 mm, stn R38, NMCR 40109, preserved colouration; C, Dardanus megistos (Herbst, 1804) . Male SL 11.0 mm, stn M8; D, Dardanus pedunculatus (Herbst, 1804) . Male SL 13.4 mm, stn N3; E, Dardanus scutellatus . Male SL 9.8 mm, stn D12; F, Dardanus woodmasoni ( Alcock, 1905 ) . Male SL 5.8 mm, stn R76. Fifth pereopods chelate; rasps of dactyl and propodus well developed. Male pleon with first to fifth left pleopod fringed with sparse setae, uniramous. Female pleon with second to fifth left pleopods fringed with long setae; first to third triramous; fourth and fifth uniramous, very large, elongate, triangular fleshy membrane fringed with long setae present between fourth and fifth pleopods. Uropods strongly asymmetrical, left larger than right; endopods and exopods with well developed rasps. Habitat. Intertidal to subtidal, 0 to approximately 20 m deep, reef flats, seagrass beds, reef slopes and plateaus, on coralline, sandy, mud-sand, rubble, and rocky substrates. Remarks. Dardanus lagopodes was described by Forskål (1775) as Cancer lagopodes from the Red Sea, and is a very common species in the Indo-West Pacific. Two colour forms have been reported for D. lagopodes , the “black/brown/ blue knee” form (colour description varies depending on author) and the “red knee” form ( Fize & Serène, 1955 as Pagurus sanguinolentus ; Lewinsohn, 1969 ; Ball & Haig, 1972 ; McLaughlin et al., 2007). In addition, considerable morphological variation has been noted for this species ( Forest, 1953b ; Fize & Serène, 1955 ; Ball & Haig, 1972 ). In the course of the present study, strong morphological, colour, and genetic differences were detected within D. lagopodes , which can now be recognised as a species complex. For the first time, it has been possible to link morphological variation with the different colour forms and with mitochondrial DNA data. Morphological and genetic differences clearly indicate that the two colour forms, the “black/brown/blue knee” (hereafter simply referred to as the “blue knee” form) and the “red knee” form, represent two distinct species. In the absence of colouration, these two species are most easily distinguished on the basis of the sculpturing on the propodus of the left third pereopod (LP3). The LP3 of the blue knee form exhibits great variation: the propodus smooth, cylindrical, and of the same width as the dactyl ( Fig. 5A ); or it may be flattened, broader, and covered with corneous spines ( Fig. 5B ). Nonetheless the LP3 propodus never bears a sulcus on its outer surface. On the other hand the red knee form is characterised by a deep sulcus on the upper half of the lateral face of the left third pereopod dactyl and propodus ( Fig. 5C ). Fig. 5. Lateral view of left third pereopod. A, Dardanus lagopodes ( Forskål, 1775 ) . Male SL 9.8 mm, stn N2, ZRC 2015.0489; B, Dardanus lagopodes ( Forskål, 1775 ) . Female SL 7.6 mm, stn R1, ZRC 2015.0488; C, Dardanus sanguinolentus ( Quoy & Gaimard, 1824 ) . Male SL 7.8 mm, stn R38, ZRC 2015.0491; D, Dardanus balhibuon , new species , holotype. Female SL 14.3 mm, stn R38, NMCR 40109. Scale bars = 1 mm. Telson with lateral constrictions; marginal area partially calcified; posterior lobes separated by median cleft, left much larger than right, each with 7 ventral corneous spines near terminal margin, terminal margins fringed with long setae; anterior lobes with long setae on lateral margins. Colour. Shield brownish purple, with large brown spot anteriorly; posterior carapace mottled red and tan. Ocular peduncles uniform purplish brown, with narrow yellow line next to black cornea. Antennules and antennae yellowish brown. Chelipeds reddish purple with white tubercles and white–tipped red setae. Pereopods 2 and 3 reddish purple; broad black band at distal end of merus and large black patch on carpus; setae reddish purple with white tips (see Haig & Ball, 1988 ). The two species are also clearly distinct genetically. Tree-based analyses (maximum likelihood and Bayesian approaches) yielded congruent results, and showed reciprocally monophyletic blue knee and red knee clades ( Fig. 9 ). No phylogeographic structuring was detected within each of the two species despite inclusion of both Philippine and Taiwan samples. Moreover, inclusion of one blue knee specimen from the Tuamotu did not increase phylogeographic structuring. Average intraspecific K2P values are 0.9% (± 0.5%) for the blue knee species and 1.5% (± 0.4%) for the red knee species. The average K2P genetic distance between blue knee and red knee species is 19.1% (± 0.4%). As a comparison, in the diogenid genus Calcinus K2P distances separating closely related sister-species ranged from 2.6% – 25% (average 16.1 ± 5.3%; see Malay & Paulay, 2010 ). Therefore, the genetic distance between blue knee and red knee Dardanus is within the range of interspecific genetic distances for diogenids. The fact that blue knee and red knee morphs maintain reciprocal monophyly and large genetic distances in sympatry is compelling evidence that they are good biological species. The phylogeny also revealed one distinctly different COI haplotype from a specimen initially identified as D. lagopodes in the field, which upon closer examination turned out to be a new species ( Dardanus balhibuon new species , described below). To which colour form the name D. lagopodes is applied has to be determined. Unfortunately, virtually all of Forskål’s types have been lost, including that of D. lagopodes (viz. Ng et al., 2008 ). However, in his very short diagnosis, Forskål (1775) mentioned the colour “cinereo-fuscus”, or gray-brown. This shows that Forskål dealt with the blue knee colour form. Moreover, Lewinsohn (1969) examined specimens from the type locality (the Red Sea) and reported the presence of both colour forms, while emphasising the brown colouration in his notes. The figure of D. lagopodes from the type locality provided by Lewinsohn (1969 : pl. 2, Figs. 1 , 2 ) matches very well with the morphological characters of the left cheliped and LP3 of the blue knee form. Furthermore, the two color forms are easily recognised and very common in intertidal areas throughout the Indo-West Pacific, thus there is no doubt that Forskål’s types D. lagopodes were of the blue knee species. The following species have long been regarded as synonyms of D. lagopodes ( Forskål, 1775 ) : D. sanguinolentus ( Quoy & Gaimard, 1824 ) ; D. affinis (H. Milne Edwards, 1836 ) ; D. euopsis ( Dana, 1852 ) ; D. depressus ( Heller, 1861 ) ; and D. hellerii Paul’son, 1875 . Quoy & Gaimard (1824) described D. sanguinolentus from a specimen probably collected in Mauritius (see Forest, 1953b , p. 560). Unfortunately their description and illustration lack sufficient detail to distinguish which species they described. Forest (1953b) examined the type specimen of D. sanguinolentus at the Muséum national d’Histoire naturelle, and noted that D. sanguinolentus has “ une depression longitudinale ” on the lateral face of propodus of the left third pereopod, while for the type of D. affinis the propodus of the third left pereopod is more elongate, the lateral face is not depressed but straight or convex (see Forest, 1953b , Figs. 13, 14). Forest (1953b) did not describe the colouration but the description of these characters already indicates that Forest was dealing with the two forms of D. lagopodes . The first author had the opportunity to re-examine the holotypes of D. sanguinolentus and D. affinis at the Muséum national d’Histoire naturelle in Paris, and confirms that the D. sanguinolentus holotype ( MNHN Pg. 1304) bears the deep sulcus on the outer face of the LP3 propodus characteristic of the red knee form. On the other hand, the D. affinis holotype ( MNHN Pg. 1305) has a smoothly convex LP3 propodus, corresponding to the D. lagopodes blue knee form. Therefore it is now possible to assign the species name D. sanguinolentus ( Quoy & Gaimard, 1824 ) to the red knee form, while D. affinis is a junior synonym of D. lagopodes . The original description of D. depressus can be applied to both D. lagopodes and D. sanguinolentus , however Heller (1861) mentioned the colouration of the species as “rubescens”. The syntypes of D. depressus were redescribed by McLaughlin & Dworschak (2001 , p. 150–151). They describe the left third pereopod of D. depressus as having a “weak longitudinal sulcus” on the lateral face of the dactyl, while the lateral face of the propodus is “concave in dorsal half”. Photographs of the syntypes (NHMW 19396, two syntypes ) kindly provided by P. Dworschak show that the description corresponds to the sulcus on the lateral face of the left third pereopod that characterises D. sanguinolentus . The depressed carapace noted in the original description of D. depressus appears to be an ecological feature related to occupation of shells with a narrow aperture ( Paul’son, 1875 ; Forest, 1953b ). The type specimen of D. euopsis could not be located for study, and is probably lost. Most of Dana’s specimens from the US exploring expedition were lent to William Stimpson, and sadly were burned in the great Chicago fire of 1871 ( Evans, 1967 ). However, Dana (1852: 453) described the colouration of the pereopods of D. euopsis as follows: “The legs are pale sepia with a dark maroon (nearly black) broad band on the third and fourth joints of the second and third pairs”. This colouration showed that Dana (1852) was likely dealing with D. lagopodes sensu stricto . Dardanus hellerii was described from the Red Sea by Paul’son (1875) . Paul’son’s type specimens cannot be located (M. Tuerkay, pers. comm.). However, Paul’son (1875) stated that his specimen was very close to D. depressus (= D . sanguinolentus ) except for its ophthalmic somite with prominent interocular structure which is oval in shape and has two distal denticles and small median groove, and the colour of the legs is yellowish with external surface of merus red. The oval shape of the interocular structure cannot be considered as a specific character of the D. hellerii , as examination of the species in the genus Dardanus revealed that all have the same structure. The colour mentioned by Paul’son (1875) matched the colour of D. sanguinolentus . Therefore it is highly likely that Paul’son was dealing with D. sanguinolentus . In conclusion, the name Dardanus lagopodes ( Forskål, 1775 ) should refer to the blue knee form. Dardanus affinis (H. Milne Edwards, 1836 ) and D. euopsis ( Dana, 1852 ) are junior synonyms of D. lagopodes . The name D. sanguinolentus ( Quoy & Gaimard, 1824 ) is relevant for the red knee species. Dardanus depressus ( Heller, 1861 ) is a junior synonym for D. sanguinolentus . Dardanus hellerii Paul’son, 1875 is a nomen dubium but if it belongs to the “ D. lagopodes ” species complex, it should also be a junior synonym of D. sanguinolentus according to the original colour description. While many published records of D. lagopodes lack sufficient detail to distinguish this species from D. sanguinolentus , by careful checking we are able to determine that D. lagopodes is known with certainty from the Red Sea ( type locality), Djibouti , East Africa, South Africa , Mayotte, Glorieuses, Madagascar , Réunion, Mauritius , Maldives , India , Cocos (Keeling) Islands , Christmas Island , Indonesia , Malaysia , Vietnam , New Guinea , Australia , Philippines , Taiwan , Japan , Marianas, New Caledonia , Loyalty Islands , Marshall Islands , Kiribati , Tuvalu , Rotuma, Wallis and Futuna , Samoa , Cooks, Society, and Tuamotu. The Philippine record of Pagurus euopsis by Estampador (1937: 503) and Estampador (1959: 51) can represent both D. lagopodes and D. sanguinolentus since no colouration or morphology account was mentioned. The present paper confirms that both D. lagopodes and D. sanguinolentus are present in the Philippines .