Pseudophilyra parilis, Komai & Shimetsugu & Ng, 2019

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 : 258-266

Pseudophilyra parilis n. sp.

[New Japanese name: Hamabe-kobushi-modoki]

( Figs. 5–8 )

Material examined. Holotype: CBM-ZC 14485 , 1 male (7.2× 6.2 mm), Maehama Beach, Funakoshi, Daiou-cho , Shima , Mie Prefecture, 34°16.11’N, 136°52.11’E, intertidal, sand, 23 July 2013, coll. S. Kimura.

Paratype: ZRC 2018.0258 , 1 male (6.5× 5.6 mm), same data as holotype ; ZRC 2018.0259 , 1 female (8.1× 7.4 mm), 1 immature female (6.0× 5.4 mm), same locality, 21 August 2013, coll. S. Kimura ; CBM-ZC 14486 , 1 male (7.3× 6.3 mm), 1 female (7.9× 7.3 mm), same locality, 26 August 2017, coll. M. Shimetsugu ; CBM-ZC 14487 , 1 male (7.0× 6.2 mm), 1 female (9.5× 8.8 mm), same locality, 8 September 2017, coll. S. Kimura ; CBM-ZC 15184 , 1 female (7.7× 6.9 mm), Saino, Shirahama , Wakayama Prefecture, 33°39.21’N, 135°21.49’E, intertidal, 1 June 2018, coll. S. Kimura.

Description. Holotype male. Carapace ( Figs. 5 , 6A ) subpyriform in general outline, 1.15 times as long as wide; dorsal surface convex, glabrous, coarsely punctate. Front ( Fig. 6B ) weakly produced anteriorly, anterior margin trilobate, median lobe subsemicircular, 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. 6C ), with low convexity just below hepatic region (pterygostomial margin); posterior margin bi-keeled, both nearly straight.

Eyestalks ( Fig. 6B ) 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. 6D ) subtriangular, anterior margin produced anteriorly with subacute median point, surface slightly depressed medially. Sternite 4 ( Fig. 6D ) largest, anterior and lateral margins coarsely granular, otherwise with sparse granules and few punctae. Sternites 5–8 becoming smaller toward posterior, surfaces with few punctae. Episternite 4 clearly demarcated from 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

Maxilliped 3 ( Fig. 6E ) almost flat, outer surface with scattered punctae. 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. 5 , 6F, G ) symmetrical, 1.5 times as long as carapace, glabrous. Merus subcylindrical, about 3.0 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. Carpus short, cup-shaped, inner surface concave; upper inner margin with row of small granules, but otherwise almost smooth. Palm compressed, 1.9 times as long as wide, slightly sinuous on outer (extensor) margin, inner (flexor) margin also slightly sinuous; upper surface almost smooth, lower surface with scattered punctae; fixed finger weakly deflexed, nearly straight, terminating in slightly curved, blunt tip; dactylus 0.7 times as long as palm, terminating in slightly curved, blunt tip; both occlusal margins meeting in distal half and forming oval hiatus in proximal half, each without conspicuous teeth.

Ambulatory legs ( Figs. 5 , 6H ) 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. 6I ) elongate-triangular, gently curved sternally. Somites 1 and 2 very short, transversely linear. Main fused section consisting of somites 3–6 elongate trapezoidal, outer surface with scattered punctae; trace of suture between somites 4 and 5 still discernible; proximolateral margin of fused somite 3 and 4 slightly expanded, lateral margin with low convexity medially. Somite 6 with trace of median tubercle somewhat proximal to distal margin; lateral margin with low convexity at proximal 0.2. Telson elongate-triangular, 1.9 times as long as wide.

Gonopod 1 ( Fig. 6J, K ) slender, slightly sinuously curved (distal half nearly straight except for outwardly curved distal part), gradually tapering, reaching nearly to suture between thoracic sternites 3/4, deeply bifurcate at distal 0.3; branches subequal in length, each terminating in acute tip. Gonopod 2 ( Fig. 6L ) about 0.3 length of gonopod 1, gently curved, proximal part slightly expanded; distal part unequally bilobed, terminal lobe bluntly pointed.

Paratype males. Agree well with holotype male. Carapace 1.13–1.15 times as long as wide. Chelipeds 1.4–1.5 times as long as carapace.

Female. Carapace ( Fig. 7A ) 1.08–1.10 times as long as wide. Front relatively slightly less produced than in males.

Exposed lateral part of thoracic sternum very narrow ( Fig. 8D ), 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. 7B ) 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 concavity, with scattered short, occasionally feathered, setae. Vulvae ( Fig. 7B, C ) small, located just posterior to mesial end of suture between sternites 5/6, outline circular, without protrusion on outer margin.

Cheliped slightly slender than that of males, 1.3 times as long as carapace; palm 2.2 times as long as wide; occlusal margins of fingers of cheliped without conspicuous teeth proximal to meeting point ( Fig. 7D ).

Pleon ( Fig. 7E ) 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 (damaged in illustrated specimen) small, subsemicircular, exceeding beyond anterior margin of thoracic sternite 3.

Colour in life. See Fig. 8 . Carapace generally gray or gray-brown, sometimes with irregular blotches of white. Thoracic sternum and pleon entirely white. Cheliped with large gray or gray-brown patches on dorsal surface of merus and palm; fingers with tint of light brown on dorsal surface; ventral surface overall white. Ambulatory legs generally white, with spots of gray or brown on meri, carpi and propodi.

Distribution. Presently known only from the type locality, Funakoshi, Daiou-cho, Shima, Mie Prefecture, Japan; intertidal to shallow subtidal sand bottom.

Remarks. Pseudophilyra parilis n. sp. closely resembles P. punctulata in the general shape and ornamentation of the carapace, the structure of the cheliped and the deeply bifurcate distal part of the male gonopod 1. The new species differs from P. punctulata in the coarser granules bordering the carapace lateral margins ( Fig. 6C versus Fig. 3C ) and the less curved distal part of the male gonopod 1 ( Fig. 6J, K versus Fig. 3I, J ). The other potentially useful characters are: in males, the sternite 4 is more strongly granular in P. parilis n. sp. than in P. punctulata ( Fig. 6D versus Fig. 3D ); the surface of the fused part of the pleon is more strongly punctate in P. parilis n. sp. than in P. punctulata ( Fig. 6I versus Fig. 3H ); and the outer margin of the female vulva is straight in P. parilis n. sp., rather than forming a rounded protrusion in P. punctulata .

Pseudophilyra tridentata was originally described from Japan on the basis of a female holotype, and has been recorded from various Indo-West Pacific localities ( Alcock 1896; Calman 1900; Laurie 1906; Rathbun 1910; Balss 1916, 1922; Stephensen 1946; Tyndale-Biscoe & George 1962; Campbell & Stephenson 1970). Komatsu & Takeda (2000) presented a redescription of the holotype, and clarified that previous records of P. tridentata by Sakai (1937, 1976) actually represent P. intermedia instead. It is likely that those records outside Japan contain species other than P. tridentata . For example, the male first gonopods illustrated by Stephensen (1946) from the Persian Gulf and Tyndale-Biscoe & George (1962) from Australia appear to be different: Stephensen’s (1946: fig. 9D) illustration shows a simple distal part, whereas Tyndale-Biscoe & George (1962: 87, fig. 7.6) specifically mentioned that “Distal third divided into two by deep cleft”. We examined Japanese specimens undoubtedly identified with P. tridentata , as well as the redescription of the holotype by Komatsu & Takeda (2000), for comparison with the new species and P. punctulata . Unfortunately, no adult male specimens of P. tridentata were available for examination, but in one immature male specimen, although the gonopod 1 was not fully developed, the distal part was already bifurcate. It can thus be assumed that P. tridentata also has a distally bifurcate gonopod 1, like P. parilis n. sp. and P. punctulata . Nevertheless, P. tridentata differs from the latter two species in many features: the frontal part of the carapace is more strongly produced with a proportionately narrower frontal margin in P. tridentata ( Fig. 10A, C ) than in the latter two species ( Figs 3A , 6A ); the lateral lobes on the frontal margin are distinctly produced in P. tridentata ( Fig. 10D ) (not produced in P. punctulata and P. parilis n. sp.; Figs. 3B , 6B ); the carapace dorsal surface is relatively smoother and less punctate in P. tridentata ( Fig. 9 ) than in P. punctulata ( Fig. 2 ) and P. parilis n. sp. ( Fig. 5 ); the mesogastric median ridge and hepatic elevations on the carapace are more prominent in P. tridentata ( Fig. 10A, C ) than in P. punctulata ( Fig. 3A ) and P. parilis n. sp. ( Fig. 6A ); the lateral margin of the carapace is nearly smooth or microscopically granular in P. tridentata ( Fig. 10B ), rather than moderately granular ( P. punctulata ; Fig. 3C ) or coarsely granular ( P. parilis n. sp.; Fig. 6C ); the male thoracic sternite 4 is finely granular anterolaterally in P. tridentata ( Fig. 10E ), whereas it is more coarsely granular in P. punctulata ( Fig. 3D ) and P. parilis n. sp. ( Fig. 6D ); and the cheliped palm is more robust in P. tridentata ( Fig. 10F, G ) than in P. punctulata ( Figs. 3F, G , 4B ) and P. parilis n. sp. ( Figs. 6F, B , 7B ) (1.8 times as long as wide in P. tridentata versus 2.0–2.2 times as long as wide in the latter two species). Furthermore, P. tridentata seems to be restricted to subtidal depths below 40 m, whereas P. punctulata and P. parilis n. sp. occur in intertidal to shallow subtidal depths.

It may be interesting to mention that the episternites 4 are partially fused to the thoracic sternite 4 in the adult male of P. punctulata ( Fig. 3D ), whereas they are fully separated from the thoracic sternite 4 in the adult males of P. parilis n. sp. ( Fig. 6D ). The significance of this character should be reassessed when more adult male specimens become available for examination.

Etymology. From the Latin “ parilis ” (adj., similar), in reference to the close similarity of the new species to Pseudophilyra punctulata .

Figures

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.

FIGURE 5. Pseudophilyra parilis n. sp., CBM-ZC 14485, holotype, male (7.2×6.2 mm), Mie Prefecture, Japan, habitus in dorsal view (left pereopod 2 missing), stained with methylene blue to show details of dorsal ornamentation of carapace.

FIGURE 6. Pseudophilyra parilis n. sp., CBM-ZC 14485, holotype, male (7.2×6.2 mm), Mie Prefecture, Japan. 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, right pereopod 5, dorsal view; I, pleon and telson, ventral view; J, left gonopod 1, ventral view; K, same, dorsal view; L, left gonopod 2, lateral view.

FIGURE 7. Pseudophilyra parilis n. sp., CBM-ZC 14486, paratype, female (7.9×7.3 mm), Mie Prefecture, Japan. A, carapace, dorsal view (dorsal ornamentation omitted); B, sternopleonal cavity, ventral view; C, right vulva, ventral view; D, right chela, dorsal view; E, pleon, ventral view (telson broken off).

FIGURE 8. Pseudophilyra parilis n. sp., CBM-ZC 14486, paratypes, male (7.3×6.3 mm) (A, B), female (7.9×7.3 mm) (C, D), showing colour in life. A, C, habitus, dorsal view; B, D, habitus, ventral view.

FIGURE 9. Pseudophilyra tridentata Miers, 1879, CBM-ZC 7846, male (6.1×5.3 mm), Okinawa Islands, Ryukyu Islands, Japan, carapace in dorsal view, stained with methylene blue to show details of dorsal ornamentation.

FIGURE 10. Pseudophilyra tridentata Miers, 1879, CBM-ZC 7846, male (6.1×5.3 mm) (A, B, D–F, H), female (8.1×7.2 mm) (C, G), Okinawa Islands, Ryukyu Islands, Japan. A, C, carapace, dorsal view (dorsal ornamentation omitted); B, left pterygostomial margin, dorsal view; D, front, dorsal view; E, thoracic sternites 3 and 4, including episternites 4; F, left cheliped, dorsal view; G, right chela, dorsal view; H, left gonopod 1, ventral view.