Macrobrachium placidum ( de Man, 1892 )

Mazancourt, Valentin De, Marquet, Gerard, Wowor, Daisy & Keith, Philippe, 2024, Macrobrachium ngankeeae, a new species of freshwater shrimp (Crustacea: Decapoda: Palaemonidae) from Papua Barat Province, Indonesia, Zootaxa 5476 (1), pp. 253-266 : 262

Macrobrachium placidum ( de Man, 1892)

Palaemon (Macrobrachium) placidus de Man, 1892: 483 , pl. 28, fig. 46

Macrobrachium placidum .— Holthuis, 1950: 251, fig. 51b; Chace & Bruce, 1993: 36

Type material. Syntype: 1 male (cl 25.9 mm), ZMA De 102.562, Sumatera Barat Province, Sumatera Island, Padang Pariaman Regency, Kayutanam, coll. M. Weber , 1888–1889.

Other material examined. 2 males (cl 16.4–18.8 mm), MNHN-IU-2016-10639, Philippines, Catanduanes Island, coll. A. March , 1903.

Diagnosis. Medium-sized species with subcylindrical body form. Rostrum short, almost reaching distal end of third article of antennular peduncle; slender; dorsal carina convex, 5 or 6 teeth completely postorbital with total 10–12 teeth on it; ventral carina convex with 2 teeth. Carapace glabrous. Ocular beak moderately developed. Third maxilliped with exopod shorter than ischiomerus. Second pereiopods robust, rather long, dissimilar in shape, unequal in size. Distal part of dactylus and pollex of major second pereiopod with double row of tubercles each, fingers slightly longer or as long as palm, carpus long conical, carpus shorter than chela, carpus longer than merus. Cutting edges of minor second pereiopod gaping, densely covered with long stiff setae concealing surface. All articles covered with modified squamiform and mamilliform setae. Third, fourth and fifth pereiopods with modified squamiform setae and few scattered short stiff setae. T4 without median process. Pre-anal carina well developed. Uropods glabrous, exopod with mobile mesial spine longer than distolateral tooth. Developed eggs small, maximum size 0.6 × 0.5 mm, ovoid, numerous.

Distribution. West coast of Sumatra, south coast of Java and southern Sulawesi, Indonesia. This species is recorded for the first time from Catanduanes Island, Philippines.