Axianassa sinica, Liu & Liu & Liu, 2010

Liu, Wenliang, Liu, Ruiyu & Liu, J. Y., 2010, First Record Of The Gebiidean Genus Axianassa Schmitt, 1924 (Crustacea: Decapoda: Gebiidea: Axianassidae) In The West Pacific, With Description Of A New Species From The South China Sea, Raffles Bulletin of Zoology 58 (2), pp. 193-197 : 193-197

Axianassa sinica , new species

( Figs. 1–3 )

Material examined. – Holotype: male (cl 4.0 mm), IOCAS R286 A- 5, Beibu Gulf, Stn. 6198, 19.87°N 106.96°E, 33 m, soft mud, Zhang coll., 12 Nov.1960.

West Atlantic species

Axianassa intermedia Schmitt, 1924 : Spanish Harbor, Curaçao; Punta Arena, Puerto Rico (Kensley & Heard, 1990)

Axianassa arenaria Kensley & Heard, 1990: Gulf of Mexico

Axianassa jamaicensis Kensley & Heard, 1990: Montego Bay, Jamaica; Mosquito Cove River, Jamaica (Felder & Manning, 1997)

Axianassa australis Rodrigues & Shimizu, 1992 : Fazenda Maricultura, Valença, Bahia, Brazil; Guaratuba, Southern Brazil (Melo, Loyola e Silva & Masunari, 2006); northern and northeastern Brazilian coast ( Coelho et al., 2007); from Florida, Texas, southwestern Gulf of Mexico to Parana, Brazil ( Felder, 2001)

Eastern Pacific species

Axianassa mineri Boone, 1931 : Pacheca Island, Pearl Islands, Bay of Panama (Pacific coast); Pacific Mexico ( Hernandez-Aguilera, 1998)

Axianassa canalis Kensley & Heard, 1990: Panama Canal

West Pacific species

Axianassa sinica , new species: Beibu Gulf (Gulf of Tonkin)

Paratype: One male (cl 2.3 mm), IOCAS X303 A-5, Beibu Gulf, Stn. 7203, 19.72°N 106.68°E, 42 m, 24 Oct.1962 .

Description. – Carapace with linea thalassinica and cervical groove clearly defined ( Fig.1A ); rostrum tapering ( Fig. 2A ), anteriorly acute, reaching well beyond cornea of eyes. Abdomen thin-walled ( Fig. 1A ), terga bearing minute setae; somite 1 somewhat shorter than half length of somite 2, pleuron produced ventrally into strong, calcified spiniform process; somite 2 longer than somites 3–6, terga with minute setae, pleuron ventrally broad; somites 3–5 subequal in length, almost naked, terga with minute setae; somite 6 longer than somites 3–5, almost naked, terga with minute setae, ventral margins sinuous. Telson ( Fig. 2B ) distinctly longer than greatest width, about 1.3 times as long as wide, posteriorly broadly rounded, bearing numerous long plumose setae.

Cornea not clearly demarcated ( Fig. 2A ), moderately pigmented. Article 3 of antennular peduncle slender ( Fig. 2A ), elongate-cylindrical, twice length of combined length of articles 1 and 2; inferior flagellum about 2/3 length of superior flagellum. Antennal acicle slender, dagger-like;

peduncle article 4 slender, elongate-cylindrical, with a small tooth on mesial margin.

Mouthparts typical of genus (e.g., Kenseley & Heard, 1990). Maxilliped 3 unarmed ( Fig. 2C ), mesial dentatc crest of ischium bearing some small teeth; merus, carpus and propodus with bands of fusiform sctae, lower margin of dactylus strongly setose.

Pereopods 1 unequal. Larger cheliped (left) ( Fig. 3A, B ) with lower margin of ischium bearing 2 sharp teeth, merus 2.0 times as long as ischium, lower margin of merus bearing 6 small teeth and one strong tooth distally; carpus triangular, about 0.67 times as long as merus; chela heavy, about 1.4 times as long as high; fixed finger slightly shorter than palm, cutting edge with small rounded teeth and one large triangular tooth on proximal 1/3; dactylus slender and slightly longer than fixed finger, cutting edge with two large rounded teeth and a row of small rounded teeth on distal 1/3. Smaller cheliped (right) ( Fig. 3C ) with lower margin of ischium bearing 2 sharp teeth, merus 1.6 times as long as ischium, lower margin of merus bearing one strong tooth distally; carpus triangular, about 0.73 times as long as merus; chela slender, about 1.5 times as long as high; fixed finger about 1.4 times as long as plam, cutting edge with a row of small teeth and one large triangular tooth on proximal 1/3; dactylus slender and slightly longer than fixed finger, cutting edge with a row of small teeth.

Pereopod 2 ( Fig. 2D ), merus with long setae on lower margin, carpus with long setae on upper margin, propodus and dactylus with setae on upper and lower margins.

Pereopod 3 ( Fig. 2E ), carpus with long setae on upper margin, propodus with dense setae on lower margin; dactylus flexed, with single row of 3 corneous spines on upper margin and row of fine spines in sinuous row on lower margin.

Pereopod 4 ( Fig. 2F ) similar to pereopod 3, but merus relatively shorter; propodus with single row of about 6 corneous spines on lower margin; flexed dactylus with single row of 4 corneous spines on upper margin and row of fine spines in sinuous row on distal half of lower margin.

Pereopod 5 ( Fig. 2G ) sub-chelate, propodus with band of dense short setae; dactylus flexed, with fine spines along lower margin

Pleopod 1 of male absent. Pleopods 2–5 similar, endopod and exopod oval-shaped.

Uropodal ramus ovate ( Fig. 2B ), elongate, uropodal exopod with a tooth on outer margin; uropodal endopod and exopod bearing dense fringe of plumose setae.

Size. – Holotype (male) cl 4.0 mm, tl 12.0 mm; paratype (male) cl 2.3 mm, tl 9.3 mm.

Remarks. – The new species is similar to Axianassa australis Rodrigues & Shimizu, 1992 , known from Brazil, in somite 1 pleuron produced ventrally into strong, calcified spiniform process and the shape of chelipeds. It differs from the latter in: 1) rostrum acute distally (versus rounded); 2) merus of pereopod 1 with a tooth distally on lower margin (versus unarmed); 3) telson elongate, about 1.3 times as long as wide (versus short and about 1.1 times as long as wide).

Etymology. – The species name is from the type locality.

Distribution and habitat. – Presently only known from the type locality. At depths of 32–42 m; bottom: soft mud.

Figures

Fig. 1. Axianassa sinica, new species. Holotype male, IOCAS R258A-5. Entire animal, lateral view. Scale = 1 mm.

Fig. 2. Axianassa sinica, new species. Holotype male, IOCAS R258A-5. A. carapace, dorsal view; B. telson and uropods, dorsal view; C. right maxilliped 3, outer view; D. pereopod 2, lateral view; E. pereopod 3, lateral view; F. pereopod 4, lateral view; G. pereopod 5, lateral view. Scale = 1 mm.

Fig. 3. Axianassa sinica, new species. Holotype male, IOCAS R258A-5. A. left larger cheliped, outer view; B. left larger cheliped, inner view; C. right smaller cheliped, outer view. Scale = 1 mm.