Galathea sinensis, Dong, Chao & Li, Xinzheng, 2010

Dong, Chao & Li, Xinzheng, 2010, Reports of Galathea Fabricius, 1793 (Crustacea: Decapoda: Anomura: Galatheidae) from Chinese waters, with descriptions of two new species, Zootaxa 2687, pp. 1-28 : 17-20

Galathea sinensis n. sp.

( Figs. 10–11 )

Type material. Holotype: MBM 150170, 1 male (3.5 mm), Nansha Islands, South China Sea, St. 94, CN SSBV 118-10 (14), 112.9 m, muddy sand, AT, 27 Dec.1989. Paratypes: MBM 150170 -1, 1 ovigerous female (3.9 mm), 5 males (2.0– 3.9 mm), 1 female (2.7 mm), same data as holotype.

Descriptions. Rostrum nearly as long as broad, 0.4 times carapace length; dorsal surface with fine setae; lateral margins each armed with 5 shallowly incised teeth. Carapace nearly as long as broad; epigastric spines absent; dorsal surface with distinct transverse ridges, first and second ridges uninterrupted, second ridge with 2 long coarse setae medially and third ridge interrupted into 3 small ridges; interrupted ridge between anteriormost branchial marginal spines directly behind anterior cervical groove on each side; mid-transverse ridge uninterrupted, preceded by indistinct cervical groove; posterior half with 4 major uninterrupted ridges and several interrupted ridges between; lateral margins medially convex, with 4 or 5 spines, first spine anterolateral, moderate-sized, posterior to level of lateral limit or orbit, second and third on anterior branchial region, fourth spine behind posterior cervical groove; lateral orbital angle ending in small spine; infraorbital margin anteriorly angular, with some lateral denticles. Pterygostomian flap rugose, with sparse short setae, anterior margin sharply produced, surface and anterior dorsal margin unarmed.

Sternal plastron slightly shorter than broad; sternite 3 1.8 times broader than long, anterior margin convex with small median sinus; Sternite 4 0.4 as long as broad, 2.4 times as broad and 2.8 times as long as sternite 3, with some striae.

Abdominal somites 2–4 each with 2 transverse ridges, ridges on somites 2 and 3 elevated.

Antennule with article 1 armed with well-developed distodorsal and distolateral spines, distodorsal spine larger, distomesial spine very small and blunt; ultimate article with several terminal setae not in tuft. Antennal peduncle with article 1 armed with blunt distomesial spine barely reaching end of article 2; article 2 with 2 terminal spines, distolateral 1 very small and nearly paralleling lateral margin of article 3, distomesial 1 directed anteromesad; article 3 with spine.

Mxp3 ischium 1.1 times as long as merus when measured along mesial margin, flexor and extensor margin each with distal spine, crista dentata (dorsal mesial ridge) with 22 denticles; merus having flexor margin with 4 or more unequal-sized spines, extensor margin with small distal spine; carpus unarmed, propodus 1.7 times longer than dactylus, 0.8 times length of carpus and 0.7 times length of merus.

P1 1.2 times as long as carapace including rostrum, relatively massive, with fine plumose setae. Merus moderately long, 0.5 of carapace length, 1.8 times longer than carpus, with 2 rows of spines, distal spine of dorsomesial spines strongest. Carpus 1.1 times as long as broad (breadth measured at midlength), 0.5 of palm length, mesial margin with 2 strong spines. Palm 1.1 times longer than broad, lateral and mesial margins subparallel; dorsal surface without spines. Fingers with coarse setae, spination as illustrated, 0.9 of palm length, each distally ending in incurved spine, opposable margins fitting each other when closed, with denticles on distal two-thirds.

P2–4 relatively slender, in subequal breadth, setose on mesial surfaces of distal 2 articles. P2 merus 0.6 as long as carapace, 2.0 times as long as carpus, with row of 11 spines on dorsal margin and 3 or more spines on distoventral margin (distal spine strong); carpus 0.7 of propodus length, with 5 or 6 spines on extensor margin, dorsolateral surface with 2 rows of eminences sub-parallel to extensor margin, flexor margin with distal spine; propodus 1.6 times as long as dactylus, flexor margin with 5 movable spines, second spine smallest and near to ventrolateral margin, extensor margin with 3 very small spines, ventrolateral margin distally ending in strong spine, lateral surface unarmed; dactylus gently curved, flexor margin with 5 proximally diminishing teeth, each with corneous spines. P3 similar to P2. P4 merus 0.5 as long as carapace, 2.0 times as long as carpus, dorsal margin with only 1 distal spine, dorsolateral surface with row of 3 spines and distoventral margin with 4 very small spines; carpus 0.7 of propodus length, with 4 spines on extensor margin, dorsolateral surface also with 2 rows of eminences sub-parallel to extensor margin, flexor margin with distal spine; propodus 1.3 times as long as dactylus, flexor margin with 5 movable spines, extensor margin with few indistinct spines, lateral surface unarmed; dactylus similar to that of P2.

Epipods present on P1, absent from P2–P4.

Etymology. The new species is named for the type locality from Chinese waters.

Distribution. Only known from the type locality, Nansha Islands, South China Sea; 112.9 m.

Remarks. Galathea sinensis n. sp. resembles G. tropis Baba, 2005 , G. multilineata Balss, 1913 , in bearing five lateral marginal teeth on the rostrum, lacking gastric spines, and bearing a reduced distomesial spine on the basal antennular article. However, the new species can be distinguished from the latter two species by the Mxp3 merus having at least four, instead of two, spines on the flexor margin. In addition, the new species differs from G. tropis in the P1 having instead of lacking epipods; it also differs from G. multilineata by the carapace having less transverse ridges on the dorsal surface, the P1 1.16 times instead of twice, as long as the carapace including the rostrum and the fingers ending distally in incurved spine instead of being distally spooned. The distomesial spine of the antennal article 1 is also different.

Figures

FIGURE 10. Galathea sinensis n. sp., MBM 150170, male. A, carapace and abdomen, dorsal view; B, left cephalic region, showing antennular and antennal peduncles, ventral view; C, endopod of right Mxp 3, distal segments omitted, lateral view. Scales = 1 mm.

FIGURE 11. Galathea sinensis n. sp., MBM 150170, male. A, right P 1, dorsal; B, left P 2, lateral view; C, left P 4, lateral view; D, sternal plastron; E, pterygostomian flap. Scales = 1 mm.