Pseudophilyra punctulata Chen & Ng, 2003

Komai, Tomoyuki, Shimetsugu, Miho & Ng, Peter K. L., 2019, Redescription and new records of a poorly known leucosiid crab, Pseudophilyra punctulata Chen & Ng, 2003, and description of a new species of Pseudophilyra from Japan (Crustacea: Decapoda: Brachyura), Zootaxa 4550 (2), pp. 251-267 : 253-258

Pseudophilyra punctulata Chen & Ng, 2003

[New Japanese name: Minami-kobushi-modoki]

( Figs. 1–4 )

Pseudophilyra punctulata Chen & Ng, 2003: 64 , figs. 1A, 2 (type locality: Siloso Beach, Sentosa, Singapore).

Pseudophilyra punctata (sic).— Ng et al. 2008: 93 (list; no new locality).

Material examined. Holotype: ZRC 1993.92 , immature male (5.8×5.0 mm), Siloso Beach, Sentosa, Singapore, coll. P.K.L. Ng & S.L. Tay, 21 December 1987.

Paratype: ZRC 1995.550 , 1 immature female (6.0× 5.4 mm), Changi Point , Singapore, coll. E. Low, 1 August 1992. Others: Japan : CBM-ZC 7024 , 1 immature male (6.1× 5.3 mm), 1 female (8.2× 7.4 mm), Uehara , Iriomote Island , Yaeyama Islands, Ryukyu Islands, subtidal sea grass beds, 8 July 2001, dip net, coll. T. Komai ; CBM-ZC 7074 , 1 female (8.7× 7.7 mm), same data ; CBM-ZC 7053 , 1 female (8.2× 7.4 mm), Shiraho , Ishigaki Island, Yaeyama Islands, subtidal sea grass beds, 1 July 2001, dip net, coll. T. Komai. Philippines : ZRC 2018.0257 , 1 immature male (4.4× 5.2 mm), station S11, in fine sand and seagrass bed, lagoon off Poblacion , 2 m, Panglao, Bohol, Visayas, 09°33.6'N 123°43.6'E, 11 June 2004, coll. Panglao Marine Biodiversity Project 2004. Thailand : CBM-ZC 12912 , 1 male (6.7×6.0 mm), Ao Tang Khen , Phuket, intertidal, sand flat with sea grass beds, 5 October 1990, coll. T. Komai ; CBM-ZC 8323 , 2 immature males (4.4× 3.9 mm, 4.6× 4.1 mm), 2 immature females (4.6× 4.2 mm, 4.9× 4.4 mm), same locality, 24 October 1995, coll. T. Komai.

Redescription. Adult male. Carapace ( Figs. 2 , 3A ) subpyriform in general outline, 1.12 times longer than broad; dorsal surface convex, glabrous, but coarsely punctate. Front ( Fig. 3 ) weakly produced anteriorly, anterior margin trilobate, median lobe subtriangular with rounded apex projecting anteriorly, distinctly exceeding lateral teeth; lateral lobe (inner orbital lobe) blunt, not particularly produced. Orbits small; supraorbital margin strongly oblique, with short, blunt lateral tooth demarcated mesially by deep, narrow longitudinal suture; bilobed anterior margin of efferent branchial channel forming lower orbital margin, inner angle acutely pointed. Hepatic region slightly inflated, forming low, dome-like elevation. Mesogastric region with obsolescent median ridge, shallowly depressed on both sides of ridge. Lateral to posterior margins keel-like, bordered with relatively coarse granules ( Fig. 3C ), with low convexity just below hepatic region (pterygostomial margin); posterior margin bi-keeled, both nearly straight.

Eyestalks ( Fig. 3A ) retractable, subcylindrical, mesial side protruding into minute blunt distal tubercle exceeding cornea. Antennular fossa continuous with orbit, partially sealed by basal plate on antennule; antennules folded slightly obliquely within fossa. Antenna very small, inserted between antennular fossa and orbit.

Thoracic sternum glabrous. Sternite 3 ( Fig. 3D ) subtriangular, anterior margin produced anteriorly, surface slightly depressed medially. Sternite 4 ( Fig. 3D ) largest, anterior and lateral margins coarsely granular, otherwise weakly granular with scattered minute punctae. Sternites 5–8 becoming smaller toward posterior, surfaces generally smooth but with few punctae. Episternite 4 partially fused with sternite 4; episternites 5–8 each with shallowly concave outer margin. Sternopleonal cavity deep, extending onto posterior part of thoracic sternite 3, margins on sternite 4, corresponding to pleomere 6 and telson, bordered with coarse granules ( Fig. 3D ).

Maxilliped 3 ( Fig. 3E ) almost flat, smooth, polished on outer surface. Ischium subrectangular, distinctly longer than wide; merus triangular, tapering distally to subacute tip, subequal in length to ischium measured along mesial margin; lateral margin of ischium and merus minutely beaded. Exopod with distal article spatuliform, lateral margin minutely beaded.

Chelipeds ( Figs. 2 , 3F, G ) symmetrical, 1.4 times as long as carapace, glabrous. Merus subcylindrical, about 3.3 times as long as wide, covered with pearly granules of various sizes except for distal one-third of upper surface and distal two-thirds of lower surfaces where granules almost absent. Carpus short, cup-shaped, inner surface concave; upper inner margin with row of small granules, but otherwise almost smooth. Palm compressed, 2.0 times as long as wide, slightly arcuate on outer (extensor) margin, inner (flexor) margin slightly sinuous; upper surface almost smooth, lower surface with scattered punctae; fixed finger slightly deflexed, nearly straight, terminating in slightly curved, blunt tip; dactylus 0.8 times as long as palm, terminating in slightly curved, blunt tip; both occlusal margins meeting in distal 0.4 and forming oval hiatus in proximal 0.6, each with few, low teeth proximally.

Ambulatory legs ( Fig. 2 ) slender, glabrous, similar in shape, gradually decreasing in length from first to fourth; each merus cylindrical; each carpus as long as or shorter than propodus; propodus somewhat compressed; each dactylus flattened, slightly curved, tapering distally to minute corneous claw, subequal in length to carpus and propodus combined.

Pleon ( Fig. 3H ) elongate-triangular, gently curved sternally. Somites 1 and 2 very short, transversely linear. Main fused section consisting of somites 3–6 elongate trapezoidal, slightly constricted at proximal one third; trace of sutures between somites 3/4 and 5/6 still discernible along lateral margin; surface with scattered punctae. Somite 6 with trace of tubercle somewhat proximal to distal margin. Telson elongate-triangular, 1.7 times as long as wide.

Gonopod 1 ( Fig. 3I, J ) slender, sinuously curved, gradually tapering, slightly twisted, reaching nearly to suture between thoracic sternites 3/4, deeply bifurcate at distal 0.3; proximal part well calcified, distal branches chitinous; inner branch slightly longer than outer branch, each branch terminating in acute tip. Gonopod 2 ( Fig. 3K ) 0.4 times as long as gonopod 1, slightly curved; proximal part expanded; distal 0.8 slender, not tapering, tip simple, rounded.

Immature males. Generally similar to adult male. Carapace ( Fig. 1A ) 1.11–1.16 times as long as wide.

Females. Carapace ( Figs. 1C , 4A ) 1.10–1.12 times as long as wide. Front slightly less produced than in males.

Exposed lateral part of thoracic sternum very narrow, smooth, forming outer wall of deeply excavated sternopleonal cavity; sutures between sternites 4/5, 5/6, 6/7 and 7/8 distinct; sternites 1–3 fused, deeply depressed below to accommodate telson. Sternopleonal cavity ( Fig. 4B ) circular in outline, margins distinctly delimited; sutures between sternites 4/5, 5/6, 6/7, and 7/8 widely interrupted medially; median suture absent; sternite 4 large, occupying anterior half of sternopleonal cavity, with scattered short, occasionally feathered, setae. Vulvae ( Fig. 4B, C ) small, located just posterior to mesial end of suture between sternites 5/6, outline generally semicircular, outer margin produced toward mesial into rounded lobe.

Cheliped ( Fig. 1C, D ) slightly slender than that of males; palm ( Fig. 4D ) 2.0 times as long as wide; occlusal margins of fingers without conspicuous teeth proximal to meeting point.

Pleon of adults ( Fig. 4C ) broad, dome-like; somites 1 and 2 short, transversely band-shaped, somite 2 about twice longer than somite 1; main fused section (somites 3–6) ovoid, no trace of sutures. Telson small, subsemicircular, exceeding beyond anterior margin of thoracic sternite 3.

Colour in life. Not known.

Distribution and habitat. Originally described from Singapore; now newly recorded from Phuket ( Thailand), Bohol ( Philippines) and Yaeyama Islands, Ryukyu Islands ( Japan); intertidal to shallow subtidal. Specimens from the Ryukyu Islands and Phuket were collected from intertidal sea grass beds formed on sand flats. The holotype male was collected from sandy intertidal areas at the edge of a coral reef near patches of seagrass.

Remarks. As noted above, the type series of Pseudophilyra punctulata consists only of two immature specimens ( Fig. 1 ). The holotype is a male, but the gonopods are not fully developed. The paratype is a female, but the pleon is narrowly triangular ( Fig. 1D ), indicating that it is also immature.

The immature specimens from Phuket (CBM-ZC 8 323) and Panglao (ZRC 2018.0257) are very similar to the type specimens. The adult male specimen from Phuket, Thailand (CBM-ZC 12912), collected from the same locality as the four immature specimens (CBM-ZC 8323) enables us to assess adult male characters, including the gonopod 1 morphology. This species characteristically has a deeply bifurcate distal part of the gonopod 1, and this character is also seen in P. parilis n. sp. and P. tridentata among known congeners (see account of P. parilis n. sp.).

Chen & Ng (2003) compared P. punctulata mainly with P. intermedia but the male gonopod 1 structure is quite different between the two species. In P. intermedia , the gonopod 1 is strongly twisted and terminates in a simple, slender process, and is never as deeply bifurcate as in P. punctulata (cf. Komatsu & Takeda 2000: fig. 2k). In addition, P. punctulata differs from P. intermedia in the better developed frontal median tooth of the carapace, and the median tubercle on the male pleomere 6 is reduced to a trace. In male P. intermedia , there is a distinct tubercle on the pleomere 6 (cf. Komatsu & Takeda 2000: fig. 4j).

Differentiating characters between P. punctulata , P. tridentata and P. parilis n. sp. are discussed under the account of P. parilis n. sp.

Figures

FIGURE 1. Pseudophilyra punctulata Chen & Ng, 2003, type specimens. A, ZRC 1993.92, holotype, immature male (5.8×5.0 mm), Singapore, carapace in dorsal view (pereopods all detached); B, same, thoracic sternum and pleon in ventral view; C, ZRC 1995.550, paratype, immature female (6.0×5.4 mm), Singapore, habitus in dorsal view; D, same, habitus in ventral view.

FIGURE 2. Pseudophilyra punctulata Chen & Ng, 2003, CBM-ZC 12912, male (6.7×6.0 mm), Phuket, Thailand, habitus in dorsal view (left pereopod 3 and right pereopods 3 and 5 missing), stained with methylene blue to show details of dorsal ornamentation of carapace.

FIGURE 3. Pseudophilyra punctulata Chen & Ng, 2003, CBM-ZC 12912, male (6.7×6.0 mm), Phuket, Thailand. A, carapace, dorsal view (dorsal ornamentation omitted); B, front of carapace and eyes, dorsal view; C, left pterygostomial margin of carapace, dorsal view; D, thoracic sternites 3 and 4, including episternites 4, ventral view; E, left maxilliped 3, outer view (setae omitted); F, right cheliped, dorsal view; G, same, ventral view; H, pleon and telson, ventral view; I, left gonopod 1, ventral view; J, same, dorsal view; K, left gonopod 2, lateral view.

FIGURE 4. Pseudophilyra punctulata Chen & Ng, 2003, CBM-ZC 7053, female (8.2×7.4 mm), Ishigaki Island, Yaeyama Islands, Ryukyu Islands. A, carapace, dorsal view (dorsal ornamentation omitted); B, sternopleonal cavity, ventral view; C, right vulva, ventral view; D, right chela, dorsal view; E, pleon and telson, ventral view.