Acutigebia serrifera, 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 : 571-574

Acutigebia serrifera , new species

( Figs. 1–3 )

M a t e r i a l e x a m i n e d. — H o l o t y p e: ♂ (c l 4. 3 m m), MBM137002 /80X-156-1, Shanhu Islands , Xisha (Spratly) Islands, in coral reef, coll. Xianqiu Ren, 19–21 May 1980. Paratype: 1 ovig . ♀ (cl 4.9 mm), MBM137002 /80X-156-1, same data as holotype .

Diagnosis. — Rostrum tapering anteriorly, provided with apical denticle, comparatively broad at base. Maxilliped 3 with exopod; merus armed with nine small teeth on lower margin. Pereopod 1 subchelate; lower margin of propodus with some small teeth. Telson subquadrate, broader than long. Uropodal endopod and exopod slender and leaf-like; endopod with single longitudinal ridge; exopod longer than endopod, with two ridges. A small species, total length of

male about 8.5 mm and ovigerous female 10.1 mm, found inside coral reef.

Description. — Rostrum ( Fig. 2A, B ) triangular, tapering anteriorly, provided with apical denticle, longer than wide (at base), extending to penultimate article of antennular peduncle; dorsal surface unarmed but setose; each lateral margin bearing some teeth. Lateral ridges of gastric region anteriorly diverging, relatively wide, not extended to middle of rostrum, tip pointed, and separated from median gastric region by longitudinal grooves; median gastric region setose and spineless. Anterolateral border of carapace unarmed; cervical groove long and deep, unarmed; postorbital region with 2–3 small spines.

Eyestalks stout, unarmed; cornea almost fully pigmented, light brown (in alcohol). Antennular peduncle about as long as antennal peduncle; second article with one ventrodistal spine. Antennal peduncle moderately stout, articles 2 and 3 each with one lower spine; article 3 with a scale ending in two sharp spines on upper surface; articles 4 and 5 unarmed. Maxilliped 3 ( Fig. 2E, F ) with simple exopod consisting of one article, reaching to end of ischium; ischium with row of small teeth on inner surface; merus with row of 10 small teeth on lower margin.

Pereopod 1 ( Fig. 3A ) subchelate. Ischium with two spines on lower margin. Merus about 2.0 times as long as high, with row of small spines on lower margin and one subterminal spine on upper margin. Carpus triangular, about 0.5 times length of merus, with one upper and one lower subdistal spines. Propodus 2.0 times as long as high, 2.2 times length of carpus, with row of small teeth on midline of lower margin surface; fixed finger triangular, narrow, terminating in acute tip, cutting edge slightly curved and with six small denticles proximally. Dactylus slender, with corneous tip, about 0.8 times length of palm; lower margin arched, smooth, unarmed; lateral surface carinate medially; upper surface carinate, corrugated in basal half.

Pereopod 2 ( Fig. 3C ) with ischium unarmed. Merus with two lower and one upper subdistal spines. Carpus unarmed. Propodus about 2.1 times as long as high, unarmed. Dactylus pointed at tip, about 0.8 times length of propodus.

Pereopod 3 ( Fig. 3D ) with ischium unarmed. Merus with four spines on lower margin. Carpus unarmed. Propodus about 1.5 times as long as high, unarmed. Dactylus slender, about as long as propodus.

Pereopod 4 ( Fig. 3E ) unarmed; dactylus elongate, slightly longer than propodus.

Pereopod 5 ( Fig. 3F ) subchelate, unarmed; dactylus elongate, curved.

Abdominal stemites smooth. Telson ( Fig. 2C ) broad, 1.5 times as wide as long and about 0.6 times length of abdominal somite 6; posterior margin slightly concave, lacking median spine.

Male pleopod 1 absent; pleopod 2–5 biramous, with exopods larger than endopods. Female pleopod 1 ( Fig. 3G ) uniramous, consisting of two articles. Uropodal protopod bearing posterolateral spine; exopod subtriangular, about 1.4 times as long as wide, truncate on posterior margin; endopod shorter than exopod, about 2.0 times as long as wide.

Variation. — Lateral ridges of gastric region broader and shorter in female than in male (cf. Fig. 2A, D ). Female pereopod 1 ( Fig. 2B ) slightly stronger than male, and different in the fixed finger being broader and shorter, and the lower teeth of the propodus extending to the base, but being smaller and inconspicuous.

Remarks. — This new species closely resembles Acutigebia simsoni ( Thomson, 1893) known from Australia ( Thomson, 1893; Poore & Griffin, 1979), in the form of the broad telson (about 1.5 times as wide as long) and pereopod 1 (ischium with 2–3 spines on lower margin and the palm with spines ventrally). However, it differs from the latter in the proportionally shorter rostrum (1.5 times longer than eyestalk versus 2.0 times as long) and the merus of pereopod 1 bearing a row of small teeth on the lower margin over the entire length, rather than having two to four teeth proximally on the lower margin.

Etymology. — The species name is based on the merus of pereopod 1, which bears a row of small teeth on the lower margin over the entire length.

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

Figures

Fig. 1. Acutigebia serrifera, new species: A, Holotype male, 80X- 156-1, entire animal, lateral view; B, paratype female, 80X-156-1, entire animal, lateral view. Scale bar = 1 mm.

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).

Fig. 3. Acutigebia serrifera, new species: A, C–F, Holotype male, 80X-156-1; B, G, paratype female, 80X-156-1. A, pereopod 1, outer view; B, pereopod 1, outer view; C, pereopod 2, outer view; D, pereopod 3, outer view; E, pereopod 4, outer view; F, pereopod 5, outer view; G, pleopod 1 with egg. Scale bar = 1 mm (A, C–F), 0.6 mm (B), 0.5 mm (G).