Garthasia ludaoensis, Hsueh, 2020

Hsueh, Pan-Wen, 2020, New species and record of xanthid crabs (Crustacean, Decapoda) from Taiwan, Zootaxa 4809 (3), pp. 535-546 : 536-540

publication ID	https://doi.org/ 10.11646/zootaxa.4809.3.7
publication LSID	lsid:zoobank.org:pub:8FE54BBA-250D-4109-8023-1A28864A7D97
persistent identifier	https://treatment.plazi.org/id/03D9878E-833A-FFE6-FF18-FBAF46969A87
treatment provided by	Plazi
scientific name	Garthasia ludaoensis
status	sp. nov.

Treatment

Garthasia ludaoensis View in CoL n. sp.

Figs 1 View FIGURE 1 A–G, 2A–E, 3A–G

Material Examined. Holotype ( NMNS 8194-001 View Materials ), male, 12.8 by 10.6 mm, Gongguan Port (22°40.55'N, 121°29.62'E), Ludao Township, Taitung County, Taiwan, subtidal hard bottom, 2 m deep, coll. H.- T. Hong, 8 August 2011. GoogleMaps

Diagnosis. Carapace oval, broader than long, length to width ratio about 1.21; dorsal surface evenly convex, region inconspicuous defined, granulose entirely except interspaces between regions; front bi-lobed with arched margins; anterolateral margin distinctly shorter than posterolateral margin, with small granules; frontal, anterolateral and anterior part of posterolateral margins with many long setae; posterolateral margin gently convex. Orbits as slits in dorsal view, eye small. Merus of third maxilliped rectangular, width to length ratio about 1.29. Chelipeds subequal in size, armed with many small teeth on dorsal margin of propodus and dactylus and outer surface of propodus; fingers subequal in length, strongly curved downward distally, gaping in a broad oval when closed. Sternum slightly elongates, without suture between sternites 1 and 2, surfaces of sternites 1 and 2 smooth. Surface of male abdomen smooth, pleonites 1 and 2 visible dorsally, telson semicircular, reaching posterior of sternum 4.

Description. Carapace oval, broader than long, width to length ratio about 1.21 ( Fig. 1 View FIGURE 1 A–C); dorsal surface evenly convex, region inconspicuously defined, granulose entirely except interspaces between regions ( Fig. 1B, C View FIGURE 1 ). Front bi-lobed, separated medially by a long narrowed cleft, lobes arched, frontal margin about 0.4 times width of carapace, finely granulated with many forward-pointing long setae ( Fig. 1 View FIGURE 1 A–C). Anterolateral margin arched, finely granulated with forward-pointing long setae, shorter than posterolateral margin. Anterior of posterolateral margin arched, finely granulated, converging towards gently convex posterior carapace margin with smooth surface ( Fig. 1 View FIGURE 1 A–C, E). Orbits poorly defined; eyes visible dorsally through an acute angular notch. Basal antennal segment rectangular, clearly separating antennular pits from orbits, flagellum short, project beyond front, antennules folding obliquely ( Fig. 1E View FIGURE 1 ). Third maxilliped longitudinal, slender, length to width ratio about 2.70, fully covering buccal field when closed, outer margins of merus and carpus with forward-pointing long setae; ischium rectangular, length to width ratio about 1.25; merus rectangular, wider than long, width to length ratio about 1.29, outer and inner angles rounded; carpus slightly inflated, approximately one-fourth as large as merus ( Fig. 1F, G View FIGURE 1 ).

Chelipeds subequal in size, right chela slightly larger than left chela, right palm about 1.25 times length of left palm ( Fig. 2A, B View FIGURE 2 ); merus rectangular, length to width ratio about 1.29, unarmed; carpus rectangular, anterior margin with a row of granules and forward-pointing long setae; propodus rectangular, anterior upheaved dorsally, dorsal margin with 2–3 rows of teeth, outer surface with scattered pinches of golden setae, anterior half of outer surface covered with rows of minute teeth, inner margin of outer surface with a row of small teeth running from posterior to anterior of propodus; fingers subequal in length, curved nearly 90° downward distally, leaving an oval gape when fully closed, 2 rows of small teeth present on dorsal margin of dactylus, forming a groove, cutting edge of right chela dactylus with a large triangular tooth proximally, a trace of a blunt tooth for left chela at same location, cutting edge of right chela pollex with 2 rectangular, offset, large teeth distally and 1 large triangular tooth proximally ( Fig. 2B View FIGURE 2 ), pollex of left chela with a row of 3 small teeth at same location, distal one largest ( Fig. 2A View FIGURE 2 ). Colour of fingers whitish ( Fig. 2A, B View FIGURE 2 ).

Ambulatory legs slender, first leg longest, fourth leg shortest with relatively robust merus (length to width ratio on 1–3 legs ranging about 1.96–2.45 versus that of 1.76 on fourth leg); merus of fourth leg unarmed, outer surface of merus, carpus and propodus smooth; 1–3 rows of small tooth present on outer margins of carpus, propodus and dactylus; a chitinous nail present at distal of dactylus; basis, ischium, carpus and propodus of fourth leg with a tuft of setae at each inner anterior corner, a row of long setae at outer margins of merus, carpus, propodus and inner margin of merus, short setae present at both margins of dactylus ( Fig. 2C View FIGURE 2 ).

Sternum slightly elongates, surface of sternites covered with many setae, suture between sternites 1 and 2 absent, sternites 2 and 3 separated by straight groove, sternites 3 and 4 separated by shallow grooves curving towards abdominal cavity, a minute longitudinal slit present at center between sternites 4 and 5 ( Fig. 2D, E View FIGURE 2 ). Male abdomen with 6 somites, pleonites 1 and 2 visible in dorsal view, pleonite 2 semicircular, pleonite 3 widest, 3–5 pleonites fused, pleonite 6 rectangular, telson semicircular, reaching posterior of sternum 4, dorsal surface of abdomen smooth, margins of all pleonites and telson covered with short to medium-length setae ( Fig. 3A, B View FIGURE 3 ).

G1 long, slender, mid-region nearly straight, slightly curved outwards subdistally, distal sharply tapering to sharp point, a lappet present next to distal opening, a tuft of long setae present near distal opening, subdistal region lined with few medium-length to long setae, surfaces of distal to mid-region covered with dense minute spines and some relatively large spines ( Fig. 3 View FIGURE 3 C–E); G2 short, basal segment distal end round, upper margin truncate without upright protrusion, distal segment elongate, slightly curved, sharply tapering to sharp point at distal area, tip spatuliform, surfaces of both segments covered with dense minute to small spines ( Fig. 3 View FIGURE 3 F–H).

Etymology. The specific name is derived from the name of the Ludao Township, where the crab was collected.

Colour. In fresh specimen, carapace surface light greenish with scatted brown speckles, becoming beige in alcohol ( Fig. 1A, B View FIGURE 1 ).

Type locality. Gongguan Port , Ludao Township, Taitung County, Taiwan .

Distribution. Only known from the type locality.

Remarks. Garthasia ludaoensis n. sp. shares several characters with G. americana ( Garth, 1939) on: 1) ovalshaped carapace with many forward-pointing long setae on margins of front, anterolateral and anterior portion of posterolateral of the carapace; 2), front separated medially by a long narrowed cleft into two lobes; 3) whitish chelipeds with distal portion of fingers strongly bend, leaving a broad oval gap when closing; 4) poorly developed orbit region; 5) slightly elongated sternum without suture between sternites 1 and 2; and 6) telson inserted to posterior of sternum 4 ( Garth 1939: 20, pl. 7, figs 1, 3; Ng 1993: 153–154, fig. 8A, D, E; Fig. 1A, B, E, H View FIGURE 1 ).

However, G. ludaoensis n. sp. can be distinguished from G. americana by having: 1) smaller width to length ratio (1.21 versus 1.35) of the carapace; 2) larger width to length ratio (3.2 versus 2.4) of the third maxilliped; 3) smaller width to length ratio of merus of the third maxilliped (1.3 versus 2.2); 4) no distinct longitudinal keel on surfaces of sternites 1 and 2; 5) smaller length to width ratio of merus (1.8 versus 2.7) of the last ambulatory leg; 6) smaller width to length ratio (2.1 versus 3.0) of pleonite 2 of the male abdomen; 7) pleonite 2 in semicircular-shaped (versus roughly rectangular); 8) a tuft of long setae (versus bared) near distal opening of G1; and 9) distal end of basal segment without upright protrusion (versus with upright protrusion) of G2 ( Ng 1993: 153,155, fig. 8E–I; Figs 1 View FIGURE 1 A–C, 2D, E, 3A, E–H).