Bathymunida avatea, Macpherson & Baba, 2006

Macpherson, Enrique & Baba, Keiji, 2006, New species and records of small galatheids (Crustacea, Decapoda, Galatheidae) from the Southwest and Central Pacific Ocean, Zoosystema 28 (2), pp. 443-456 : 448-451

Bathymunida avatea n. sp.

( Figs 3 ; 4 )

TYPE MATERIAL. — Holotype: French Polynesia. Austral Archipelago. BENTHAUS, stn CP 1989, 22°36,20’S, 150°59,99’W, 456 m, 22.XI.2002, ovig. ♀ 5.0 mm (MNHN-Ga 5304).

Paratypes: same station as for the holotype, 4 ♂♂ 4.1- 5.0 mm; 8 ovig. ♀♀ 4.2-5.3 mm; 1 ♀ 3.2 mm (MNHN- Ga 5306).

Tonga. BORDAU 2, stn DW 1534, 302- 307 m, 1 ♂ 4.3 mm (MNHN-Ga 5305).

ETYMOLOGY. — The name refers to the goddess of the moon of Polynesian mythology (Avatea).

DISTRIBUTION. — Tonga and French Polynesia, 302- 456 m.

DESCRIPTION

Carapace 1.2 times as wide as long; dorsal surface with weak, relatively sparse striae. Gastric and cardiac regions somewhat elevated in profile, each with sharp, anteriorly directed, moderate-sized median spine.Two epigastric spines.Mesial part of branchial region longitudinally elevated, anteriorly with blunt postcervical spine. Frontal margin strongly concave. Anterolateral spine well developed, not overreaching supraocular spines and followed by one or two small spines on hepatic margin. Branchial margin with four spines.

Rostrum slightly wider than long, 0.2 times as long as carapace, laterally elevated; rostral spine reaching end of corneae, horizontal, slightly longer than rostrum, with dorsal rounded carina continued posteriorly on to anterior portion of rostrum.

Sternal plastron 2/3 as long as broad, sternites successively broader posteriorly. Sternite 3 having anterior margin moderately convex with weak median concavity, surface slightly depressed medially, width half that of following sternite; anterior margin of sternite 4 contiguous with entire posterior margin of sternite 3, surface slightly depressed medially.

Abdominal segment 2 with four spines on anterior ridge, median 2 prominent, lateral one short and blunt; segments 3-4 each with two median spines on anterior ridge, posterior ridge of segment 4 with acute median spine.

Eyes well developed, depressed, corneae without eyelashes.

Antennular peduncle slightly overreaching cornea, with two small blunt distal spines, distolateral spine slightly larger than distomesial,lateral border unarmed. Basal article of antennal peduncle with strong distomesial spine reaching end of article 2; article 2 with strong distomesial spine reaching end of article 4, distolateral spine small; articles 3 and 4 unarmed.

A

Mxp 3 ischium 1.5 times longer than merus, flexor and extensor margins each with blunt distal spine. Extensor margin of merus with small distal spine, flexor margin with well developed median spine.

Male P1 missing. Female P1 subcylindrical, long and slender, 3-4 times longer than carapace, surface granulate. Merus 1.4-1.9 times longer than carpus; carpus 6.4-6.8 times longer than broad and 0.8-0.9 times length of palm; palm 2-3 times longer than fingers. Merus with row of spines along mesial and dorsal sides; carpus with three or four spines on mesial margin and a few on dorsal side; palm with mesial row of spines; fingers unarmed.

P2-4 moderately slender, surface granulate. P2 1.7-2.3 times longer than carapace. Meri successively shorter posteriorly, each of extensor and flexor margins with distal spine. P2 merus about 4 times longer than wide, 1.5-1.7 times longer than propodus; extensor margin of carpus with distal spine; propodus slightly longer than dactylus, with some movable spinules along flexor margin; dactylus slightly curving, somewhat more so on P3 and P4, flexor margin with three movable spine-like setae.

P 5 in male without ribbon-like setae on propodus.

REMARKS

Bathymunida avatea n. sp. belongs to the group of species with rostral and supraocular spines separated by a concave margin, and supraocular spines shorter than the rostral spine. The new species is most similar to B. sibogae van Dam, 1938 , from New Caledonia, Chesterfield Islands, Indonesia and Japan, in 205-350 m ( Baba & de Saint Laurent 1996; Baba 2005).

The two species are easily distinguished by the following characters:

– the dorsal surface of the carapace has numerous distinct transverse ridges in B. sibogae , whereas this surface has scale-like ridges in the new species;

– the distomesial spine of the basal segment of the antennal peduncle reaches the end of article 2 in the new species, whereas this spine is clearly shorter in B. sibogae . Furthermore, the distolateral spine of the article 2 is long, reaching the end of article 3 in B. sibogae , whereas this spine terminates in the mid-length of that article in the new species.

Figures

FIG. 3. — Bathymunida avatea n. sp., ovigerous ♀ holotype, French Polynesia (MNHN-Ga 5304): A, carapace and abdomen, dorsal; B, same, lateral. Scale bar: 2 mm.

FIG. 4. — Bathymunida avatea n. sp., ovigerous ♀ holotype, French Polynesia (MNHN-Ga 5304): A, left antennule, antenna, eye and anterior part of pterygostomian flap, ventral; B, sternal plastron; C, right Mxp 3, ischium and merus, lateral; D, right P1, dorsal; E, right P2, setae omitted, lateral; F, same, dactylus; G, right P3, setae omitted, lateral; H, right P4, setae omitted, lateral. Scale bar: A, C, F, 1 mm; B, D, E, G, H, 2 mm.