Galathea babai, 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 : 4-5

Galathea babai n. sp.

( Figs. 2–3 )

Type material. Holotype: MBM 150230, ovigerous female (3.1 mm), Mengzijiao, Nansha Islands, South China Sea, CN 4-5, 78 m, coral reef, TT, 25 May 1990. Paratype: MBM 150231, 1 male (4.1 mm), same collection data as holotype.

Description. Rostrum broad triangular, with 4 lateral teeth, nearly as long as broad, 0.3 as long as and 0.4 as wide as carapace. Carapace 0.9 as long as broad; dorsal surface with some short striae and transverse ridges; lateral margins slightly convex, with 6 spines on each side. Anterolateral (first) spine pronounced, second spine ventral and slightly posterior to anterolateral spine, much smaller than spines behind anterior cervical groove. Lateral orbital angle ending in small spine; infraorbital margin angular anteriorly. Anterior first transverse ridge with 2 pairs of submedian epigastric spines; third transverse ridge with extremely strong median protogastric spine. Anterobranchial spine only on right side in holotype (absent on left side of holotype and both sides of paratype). First and second transverse ridges short, interrupted ridge between anteriormost branchial marginal spines directly behind anterior cervical groove on each side; third and fourth interrupted. Four major uninterrupted transverse ridges present on posterior half of carapace. Pterygostomian flap rugose, with sparse short setae, anterior margin approximately roundish, surface and anterior dorsal margin unarmed. Sternal plastron as long as broad. Sternite 3 broader than long, anteriorly subtriangular, with small median sinus. Sternite 4 (including posterior lateral projection) 1.3 times as broad as sternite 3, with some ridges. Sternites 5–7 smooth.

Abdominal tergites 2–4 each having 2 setiferous transverse ridges. Telson 0.6 as long as broad, indistinctly subdivided by shallow sutures. Paratype male with 2 pairs of gonopods.

Antennular peduncle with article 1 armed with 3 well-developed distal spines, distomesial spine slender, distodorsal spine largest; ultimate article with a few short setae distally.

Article 1 of antennal peduncle with blunt distomesial spine barely reaching end of article 2. Article 2 with 2 well-developed distal spines, distomesial spine slightly smaller than distolateral and barely reaching midlength of article 3, distolateral spine reaching end of article 3. Article 3 with incurved distomesial spine hardly reaching end of article 4.

Mxp3 ischium 1.2 times as long as merus when measured along mesial margin, with small distal spine on flexor margin; extensor margin unarmed; crista dentata with 21 denticles. Merus having flexor margin with 5 or more unequally sized spines located in distal half; extensor margin with small distal spine. Carpus unarmed. Propodus 1.48 times longer than dactylus, 0.8 length of carpus.

P1 1.4 times length of carapace, relatively massive, with setae and rows of spines. Merus 0.6 as long as carapace, 1.8 times longer than carpus, with 2 rows of spines, distalmost of dorsomesial spines strongest. Carpus 0.9 as long as breadth at midlength, 0.5 length of palm; mesial margin with 4 strong spines, third spine prominent; lateral margin with 3 strong spines. Palm 1.2 times longer than broad, lateral and mesial margins subparallel; spines arranged roughly in 5 rows (except marginal spines); lateral spines continued on to entire length of fixed finger. Fingers 0.7 length of palm, each distally ending in incurved spine; opposable margins fitting each other when closed, with denticles on distal two-thirds of length.

P2–P4 relatively slender, breadths subequal, setose mesial surfaces. P2 merus 0.6 length of carapace, with 7 spines on dorsal margin and 1 on distoventral margin. Carpus 0.7 length of propodus, with 6 spines on dorsal margin and 3 spines on lateral surface. Propodus 1.4 times as long as dactylus, flexor margin with 4 movable spines and extensor margin with 7; lateral surface with 2 proximal spines subparallel to extensor margin. Dactylus gently curving, flexor margin with 5 proximally diminishing teeth, each with corneous spines. P3 and P4 similar to P2 with exception of small differences in number and size of spines.

Epipods absent from P1–P4.

Etymology. The species name is given in honour of the Japanese carcinologist, Prof. Keiji Baba, who kindly gave us important advice for our galatheid research and provided pertinent references.

Distribution. Only known from the type locality, Mengzijiao, Nansha Islands, South China Sea, 78 m depth.

Remarks. Galathea babai n. sp. is unique in the genus in having the strong median protogastric spine on carapace. The new species is close to G. australiensis , G. cymbulaerostris Tirmizi, 1966 , and G. tanegashimae in the absence of uninterrupted striae between the anteriormost branchial marginal spines directly behind the cervical groove, the hepatic lateral margin with a small but distinct spine, and the absence of spines on the pterygostomian flap. Galathea babai is distinguished from these species by having at least five instead of two spines on the flexor margin of Mxp3 merus and in the P1 carpus being nearly as long as broad or slightly longer than broad, instead of more than 1.5 times longer than broad.

Figures

FIGURE 2. Galathea babai n. sp., MBM 150230, ovigerous female. A, carapace and abdomen, dorsal view; B, right cephalic region, showing antennular and antennal peduncles, ventral view; distal segments omitted, lateral view; C, endopod of right Mxp 3; D, sternal plastron; E, pterygostomian flap. Scales = 1 mm.

FIGURE 3. Galathea babai n. sp., MBM 150230, ovigerous female. A, left P 1, dorsal view; B, left P 2, lateral view; C, left P 3, lateral view; D, right P 4, lateral view; E, right P 5. Scales = 1 mm.