Paragourretia galathea (K. Sakai, 2017)

Padate, Vinay P., Cubelio, Sherine Sonia & Takeda, Masatsune, 2022, Two axiidean ghost shrimps (Crustacea: Decapoda) from India, Guyanacaris keralam sp. nov. (Axiidae) and Paragourretia galathea (K. Sakai, 2017) (Ctenochelidae), Zootaxa 5093 (2), pp. 195-217 : 209-213

Paragourretia galathea (K. Sakai, 2017)

( Figs 5–7 )

Tuerkaygourretia galathea K. Sakai, 2017b: 1133 , figs 4, 5 (in part); Poore et al. 2019: 121 (synonymy, see remarks for Paragourretia Sakai, 2004 ).

Paragourretia galathea . Poore et al. 2019: 137 ( Table 1 ), 146 ( Table 2 ).

Material examined. Male ( CMLRE / IO /SS/AXI/00002, CL 8.5 mm, TL 25.6 mm), Arabian Sea, west off Koyilandi (Quilon), Kerala, India, FORVSS station 34013, 11.36ºN, 74.91ºE, 100 m depth, 25 May 2015, Naturalist’s dredge, coll. Dr. K.U. Abdul Jaleel ; male ( CMLRE / IO /SS/AXI/00003, CL 9.0 mm, TL 29.0 mm), Arabian Sea , west off Panaji, Goa, India, FORVSS station 34003, 15.47ºN, 73.07ºE, 105 m depth, 22 May 2015, Naturalist’s dredge, coll. Dr. K.U. Abdul Jaleel.

Diagnosis. Rostrum triangular, distal tip short of distal margin of ocular lobes ( Figs 5A–B , 6A–D ). Carapace smooth, unarmed; dorsal oval absent; cervical groove located in posterior third portion of carapace; linea thalassinica entire, cardiac prominence present ( Figs 5A–B , 6A–B, D ).

Pleomeres smooth, glabrous dorsally; pleomeres 1–2 relatively longer than pleomeres 3–5; pleomere 6 subquadrate dorsally; pleomeres 3–6 pleural margins convex ( Figs 5A–B , 6D ).

Ocular lobes triangular, dorsal surface gently convex, directed obliquely downwards; distal tip obtuse, extending to midlength of basal antennular article; cornea distal, darkly pigmented ( Fig. 6A–C ). Antennular peduncle shorter than antennal peduncle by length of distal antennular article, terminal article slightly longer than penultimate article ( Fig. 6A–C ). Scaphocerite small, triangular; terminal article shorter than penultimate one ( Fig. 6A–C ).

Maxilliped 3 endopodal ischium sub-rectangular, unarmed ( Fig. 6E ), crista dentata with 15 teeth and 4 minute denticles ( Fig. 6F ); merus sub-rectangular, bearing 1 spine mesiodistally; carpus narrow proximally, ventral margin widened distally, unarmed; propodus subovate, ventral margin widened proximally; dactylus digitiform; exopod short, flagellum not reaching base of endopodal merus, bearing long distal setae ( Fig. 6E ).

P1 unequal, dissimilar. Major (right) cheliped ischium elongate, dorsal margin convex distally, ventral margin bearing 1 distinct subdistal denticle; merus deeper than ischium, dorsal margin gently convex, ventral margin bearing 1 sharp tooth proximally, distal portion rough, blade-like. Carpus posteroventral angle convex, rough, blade-like, carpal margins bearing long setae. Chela dorsal margin smooth, ventral margin up to proximal portion of pollex rough, blade-like, both margins bearing long setae; dactylus gently curved, dactylar occlusal margin with high sharp ridge in proximal half, that of pollex finely denticulate proximally, distal portions of both fingers smooth, unarmed, distal tips crossed in closed position ( Fig. 7A ).

Minor (left) cheliped slender; ischium slender, dorsal margin convex distally, margins unarmed; merus deeper than ischium, dorsal margin gently convex, ventral margin bearing 1 sharp tooth proximally, distal portion rough, blade-like. Carpus posteroventral angle convex, rough, blade-like, margins bearing long setae. Chela dorsal margin smooth, ventral margin up to proximal portion of pollex rough, blade-like, both margins bearing long setae; dactylus elongate, distal one-third portion gently curved, evenly tapering, occlusal margin of both fingers unarmed, distal tips crossed in closed position ( Fig. 7B ).

P2 chelate, ischial ventral margin protruding distally; meral ventral margin convex bearing closely-set long setae; carpal height subequal to that of merus; chela margins bearing long setae; dactylus elongate, tapering, distal tip curved, occlusal margin unarmed, fingers crossed in closed position ( Fig. 7C ). P3 simple; ischial ventral margin protruding distally; meral dorsal margin convex in distal half; carpal distal margin bearing long setae; propodus elongate, dorsal margin gently convex, ventral margin nearly straight, all surfaces and margins bearing setal tufts; dactylus slender, triangular ( Fig. 7D ). P4 simple; merus slender; carpus slender; propodus subovate, bearing closelyset setal tufts on all surfaces and margins; dactylus slender, triangular ( Fig. 7E ). P5 sub-chelate; acute disto-ventral extension of propodus forming sub-chela with dactylus; dactylus narrow, dorsal margin convex, ventral margin distinctly concave, distal tip blunt ( Fig. 7F ).

Male pleopod 1 uniramous, bi-articulate; proximal article longer than distal article; distal article widened and chelate distally, curved acute apex and broadly triangular subdistal lobe separated by deep notch ( Fig. 7G, J ). Pleopod 2 endopod bearing appendix masculina and appendix interna attached at distal one-thirds portion ( Fig. 7H, K ). Pleopods 3–5 exopods shorter than ovate endopods, appendices internae slender.

Telson trapezoid, lateral margins parallel along anterior two-fifths portion, gently tapering distally, distal margin broadly convex, setose, bearing acuminate median spine; dorsal surface with median longitudinal groove ( Fig. 7I ). Uropodal endopod subquadrate, convex distally, dorsal surface bearing low median ridge ( Fig. 7I ). Uropodal exopod bearing blunt spinule proximally, broadly expanded distally, dorsal surface bearing transverse elevation medially divided by groove, lateral notch present ( Fig. 7I ).

Colouration (preserved in formalin for six years and recently transferred to 70% ethanol) is off-white ( Fig. 5A–B ).

Remarks. Ghost shrimps of the genus Paragourretia K. Sakai, 2004 resemble those of the genus Gourretia de Saint Laurent, 1973 , but clearly differ from the latter in the absence of teeth on the occlusal margin of the minor cheliped fingers, tapering lower proximal margin of the major cheliped carpus, the presence of marginal notch and dorsal plate on the uropodal exopod, and the mesial position of the appendices interna and masculina on the endopod of the male pleopod 2 ( Poore et al. 2019).Recently, Sakai (2017b) described a new genus and species Tuerkaygourretia galathea from one female and two males collected from the southwest Bay of Bengal off Tranquebar, India, two females from the northwest Bay of Bengal and one male off Singapore. However, Poore et al. (2019) opined that the illustrations of the chelipeds and the male pleopods indeed represented separate species from hitherto-known genera Gourretia and Paragourretia , which were confounded into a single morphological description, and therefore resulted in synonymizing Tuerkaygourretia with Paragourretia . According to Poore et al. (2019), the holotype was depicted only in figures 4A–C, E, F and 5A–C, E, G (Sakai 2017), and were used to compare the present material.

In view of the above, the genus Paragourretia is now represented by eight extant species namely Paragourretia aungtonyae (K. Sakai, 2002) , P. biffari ( Blanco Rambla & Liñero Arana, 1994) , P. coolibah ( Poore & Griffin, 1979) , P. crosnieri ( Ngoc-Ho, 1991), P. galathea (K. Sakai, 2017b) , P. laevidactyla (WL Liu & RY Liu, 2010) , P. phuketensis (K. Sakai, 2002) and P. portsudanensis (K. Sakai, 2005) , with known circumtropical distribution. The ambiguous description of the type specimens of P. galathea (deposited in the Zoological Museum, University of Copenhagen) necessitated a redescription.

The present specimens from the Arabian Sea were compared carefully with the eight known species about the relative lengths of the rostrum, ocular lobe and antennular peduncle, the armature of the third maxilliped merus, and the shape and armature of the telson. They were identified as P. galathea in spite of the following two differences from the holotype from the Bay of Bengal. 1) The terminal antennular article in the present specimens is slightly longer than the penultimate article [vs. terminal article is slightly shorter than the penultimate article in the holotype], but this character may be delicate, with possible individual or developmental variation; 2) A distomedian spine is present on the telson in the present specimens [vs. telson is unarmed in the holotype], but the spine is small, semi-transparent and partly disguised under the marginal hairs, with unavoidable omission. This problem on such differences may be settled with examination of the additional topographical specimens.

Distribution. Bay of Bengal, off Tranquebar (11.10°N, 80.08°E) at 94 m, 20.62°N, 87.55°E at 50 m depth ( Sakai 2017b); Arabian Sea, off Quilon at 100 m, off Panaji at 105 m.

Figures

FIGURE 5. Paragourretia galathea (Sakai, 2017), male, CL 9.0 mm, TL 29.0 mm (CMLRE/IO/SS/AXI/00003). Photographs. A, Dorsal habitus; B, Lateral habitus. Scale bar: 5 mm.

FIGURE 6. Paragourretia galathea (Sakai, 2017), male, 9.0 mm CL, 29.0 mm TL (CMLRE/IO/SS/AXI/00003). A, Carapace, ocular plates, antennular and antennal peduncles, dorsal view; B, Carapace, left ocular plate, left antennular and antennal peduncles, lateral view; D, Dorsal habitus. Male, 8.5 mm CL, 25.6 mm TL (CMLRE/IO/SS/AXI/00002). C, Rostrum, ocular plates, antennular and antennal peduncles, lateral view; E, Right maxilliped 3, outer view; F, Right maxilliped 3 ischium, inner view. Scale bar: D = 5 mm; A, B = 2 mm; C, E–F = 1 mm.

FIGURE 7. Paragourretia galathea (Sakai, 2017), male, 8.5 mm CL, 25.6 mm TL (CMLRE/IO/SS/AXI/00002). A, Right P1, lateral view; B, Left P1, lateral view; C, Left P2, lateral view; D, Right P3, lateral view; E, Left P4, lateral view; F, Right P5 (denuded), lateral view; G, male right pleopod 1, posterior view; H, Male right pleopod 2 showing appendix interna and appendix masculina, posterior view; I, telson and uropods, dorsal view. Male, 9.0 mm CL, 29.0 mm TL (CMLRE/IO/SS/AXI/00003). J, Male right pleopod 1 distal portion, posterior view; K, male right pleopod 2 showing appendix interna and appendix masculina, posterior view. Scale bar: A, B, F, I = 2 mm; C–E, G, H, K = 1 mm; J = 500 µm.