Acutigebia laticauda, Liu & Liu & Liu, 2013

Liu, Wenliang, Liu, Ruiyu & Liu, J. Y., 2013, Two New Species Of Acutigebia (Crustacea: Decapoda: Gebiidea: Upogebiidae) From The South China Sea, Raffles Bulletin of Zoology 61 (2), pp. 571-577 : 574-577

Acutigebia laticauda , new species

( Figs. 4–6 )

Material examined. — Holotype: ♀ ovig. (cl, 2.9 mm), MBM136974 /58C-S63, Jinqing Island of Xisha (Spratly) Islands, in coral reef, coll. Zhengang Fan & Jieshan Xu, 25–26 Apr.1953.

Diagnosis. — Rostrum tapering anteriorly, broader, and shorter than the width (at base), aprovided with an apical denticle. Maxilliped 3 exopod present, merus ornamented with two small teeth on lower margin. Pereopod 1 subchelate; lower margin of propodus unarmed. Telson subquadrate, broader than long. Uropodal endopod and exopod slender and leaf-like; endopod with single longitudinal ridge; exopod with double ridge, longer than endopod. A small species, total length of ovigerous female about 9.0 mm, found inside coral reef.

Description. — Rostrum ( Fig. 5A, B ) triangular, tapering anteriorly, broad and short, about 0.65 times as long as wide at base, provided with an apical denticle, extending to the penultimate article of antennular peduncle; dorsal surface unarmed and without seta; each lateral margin bearing some teeth. Lateral ridges of gastric region anteriorly diverging, relatively wide, extending to the middle of rostrum, tip pointed, and separated from median gastric region by longitudinal grooves; median gastric region unarmed. Anterolateral border of carapace with some teeth; cervical groove long and deep, unarmed; postorbital region unarmed.

Eyestalks stout, unarmed, cornea almost fully pigmented, light brown (in alcohol). Antennular peduncle about as long as antennal peduncle, unarmed. Antennal peduncle thick, articles 2 and 3 with one lower spine each; article 3 with ovate scale of one tooth at tip on upper surface; article 4 and 5 unarmed. Maxilliped 3 ( Fig. 5D ) exopod present, with flagellum, reaching to distal part of ischium; ischium with row of small teeth on inner surface, merus with two small teeth on lower margin.

Pereopod 1 subchelate ( Fig. 6A ). Ischium unarmed. Merus about 2.0 times as long as high, with a subterminal spine on upper margin. Carpus triangular, about 0.6 times length of merus, with a lower subdistal spines. Propodus 2.0 times as long as high, 2.2 times length of carpus, unarmed; fixed finger triangular (distally broken), cutting edge slightly curved and with four small denticles proximally; dactylus slender with corneous tip, about 0.7 times length of palm, lower margin arched, smooth, unarmed; lateral surface carinate medially, upper surface carinate, corrugated in middle.

Pereopod 2 ( Fig. 6B ) with ischium unarmed. Merus unarmed, about 3.5 times as long as high. Carpus about 0.4 times length of merus, each with a terminal spine on upper and lower margin. Propodus about 1.8 times as long as high, unarmed. Dactylus pointed at tip, about 0.8 times length of propodus.

Pereopod 3 missing. Pereopod 4 ( Fig. 6C ) with ischium unarmed. Merus unarmed, about 3.6 times as long as high. Carpus about 0.6 times length of merus. Propodus about 2.0 times as long as high, bearing four small blunt subterminal spines on lower margin. Dactylus pointed at tip, slightly longer than propodus, bearing some sharp spines on distal half of lower margin and six small blunt spines on basal half of upper margin.

Pereopod 5 ( Fig. 6D ) subchelate, unarmed; dactylus elongate, curve.

Abdominal stemites smooth. Telson ( Fig. 2C ) broad, about 1.7 times as wide as long and about 0.6 times length of abdominal somite 6; posterior margin straight, lacking median spine.

Female pleopod 1 ( Fig. 6E ) uniramous, consisting of two articles. Uropodal protopod without posterolateral spine; exopod subtriangular, about 1.4 times as long as wide, truncate on posterior margin; endopod shorter than exopod, about 1.9 times as long as wide.

Remarks. — Acutigebia laticauada , new species, closely resembles Acutigebia trypeta ( Sakai, 1970) known from Japan ( Sakai, 1970), in the palm of pereopod 1 palm being unarmed on the lower margin and the rectangular telson being broader than long. It differs from the latter in the relatively wider telson (about 1.7 times as wide as long versus about 1.5 times as wide), the relatively short and broad rostrum (about 0.65 times as long as wide at base versus about 1.2 times as long as wide), and the merus of pereopod 1 being unarmed, rather than bearing several teeth on the lower margin.

Etymology. — The species name is based on the short and wide shape of the telson.

Distribution and habitat. — Presently only known from the type locality. The specimen were found living in the narrow tunnels of coral reef.

Figures

Fig. 4. Acutigebia laticauda, new species: Holotype female, 58C- S63, entire animal, lateral view. Scale bar = 1 mm.

Fig. 5. Acutigebia laticauda, new species: Holotype female, 58C-S63. A, anterior carapace, dorsal view; B, anterior carapace, lateral view; C, abdominal somite 6, telson and uropods, dorsal view; D, maxilliped 3, outer view. Scale bar = 1 mm (A, B, D), 0.5 mm (C).

Fig. 6. Acutigebia laticauda, new species: Holotype female, 58C-S63. A, pereopod 1, outer view; B, pereopod 2, outer view; C, pereopod 4, outer view; E, pleopod 1 with egg. Scale bar = 1.32 mm (A, C), 1 mm (B, D, E).

Fig. 2. Acutigebia serrifera, new species: A, B, C, D, E, Holotype male, 80X-156-1; D, paratype female, 80X-156-1. A, anterior carapace, dorsal view; B, anterior carapace, lateral view; C, abdominal somite 6, telson and uropods, dorsal view; D, anterior carapace, dorsal view (rostrum broken); E, maxilliped 3, outer and inner view. Scale bar = 0.6 mm (A, B, D), 1 mm (C), 0.8 mm (E).