Maeropsis paphavasitae, Wongkamhaeng, Koraon, Coleman, Charles Oliver & Pholpunthin, Pornsilp, 2013

Wongkamhaeng, Koraon, Coleman, Charles Oliver & Pholpunthin, Pornsilp, 2013, Maeropsis paphavasitae and Rotomelita longipropoda, two new species (Crustacea, Amphipoda) from Lower Gulf of Thailand, ZooKeys 307, pp. 15-33 : 17-19

Maeropsis paphavasitae sp. n.

Type material.

Holotype. ♂, THAILAND, Lower Gulf of Thailand, Talet Bay (09°18'39.5"N, 99°46'46.4"E), seagrass bed (associated with Thalassia hemprichii ), 1 May 2008, Puttapreecha, R., PSUZC-CR-0198.

Paratypes, collected with holotype ZMB 27979 (3♀); PSUZC-CR-0199 (3♂; 5♀)

Description.

Based on male holotype. Body length 5.1 mm (from tip of rostrum to apex of telson). Body compressed, subcylindrical. Head, lateral cephalic lobe truncate, without rostrum, eyes round. Antenna 1, ratios of peduncular articles 1-3 9:10:2.5; peduncular article 1 with a ventromarginal robust seta and a distoventral robust seta; accessory flagellum with 6 articles.

Upper lip, (labrum) distally rounded. Lower lip, inner lobes small, pubescent; outer lobes covered with thin hair-like setae. Mandible, both incisors with 7 teeth; lacinia mobilis armed with 5 teeth on the left side and 4 teeth on the right side; molar short, cylindrical; palp 3-articulate with ratios of 4:9:3, article 2 with marginal setae and article 3 with apical setae. Maxilla 1, inner plate with 3 plumose setae apically and marginal fine setae medially; outer plate with 6 serrate robust setae apically; palp 2-articulate with apical fine setae. Maxilla 2, inner plate with lateral and medial marginal setae; outer plate broader than inner plate, distally setose. Maxilliped, inner plate with 9 plumose setae; outer plate semi-oval, inner margin with 9 robust setae distally; palp 4-articulate, article 3 with 15 fine setae, article 4 with 6 fine marginal setae.

Pereon.Gnathopod 1 subchelate, smaller than gnathopod 2; coxa anterodistally produced; basis posterior margin with 3 setae, longer than ischium and merus combined; carpus posterior margin and lateral surface densely setose; palm oblique. Gnathopod 2, basis with 2 posterior marginal setae; ischium and merus short; carpus triangular; propodus robust, subrectangular, 1.5 × longer than broad with posterior marginal plumose setae, palm transverse with 6 blunt teeth and an acute palmar corner, inner face bearing 1 subposterodistal robust seta; dactylus fits with palm, inner margin smooth, outer margin with 1 long seta. Pereopod 3-4 similar to each other, basis with anterior and posterior marginal setae. Pereopod 5 basis oval, posterior margin slightly produced distally, posterodistal lobe rounded. Pereopod 6- 7 similar, basis broader than pereopod 5, posterodistally produced with short anterior and posterior marginal setae; dactyli curved.

Pleon. Epimera 1-2 posteroventral corner smooth, not produced. Epimeron 3 produced posteroventrally, with 3 short ventral setae. Uropod 1 longest, peducle longer than rami, posterior margin fringed with robust setae, anterior with 1 basofacial robust seta. Uropod 2, peduncle shorter than both rami; inner ramus longer than outer ramus. Uropod 3, peduncle shorter than rami; inner ramus subequal to outer ramus, distally truncate; inner ramus bearing only 1 proximal robust seta and 4 terminal setae. Telson longer than wide, cleft more than 95% of its length, lobes distally incised, outer end of incision longer than inner one, with 3 long apical setae and 2 lateral plumose setae.

Female. (sexually dimorphic characters). No sexual difference.

Etymology.

The species is named in honor of Associate Professor Nittharatana Paphavasit of Chulalongkorn University, Thailand who contributed to the knowledge on seagrass habitats in Thailand.

Remarks.

Maeropsis paphavasitae sp. n. is very similar to Maeropsis serratipalma (Nagata, 1965) in the palm of gnathopod 2, which is transverse with 6 blunt teeth and a large defining tooth in both species. But the new species can be distinguished from Maeropsis serratipalma by the following characters: gnathopod 1 palm without clear defining palmar corner; gnathopod 2, merus not produced into a posterodistal tooth (vs. produced); propodus of gnathopod 2 subtriangular (vs. subrectangular), palm inner surface with 1 subposterodistal robust seta (vs. without); dactyli of pereopods 3-7 curved and smooth (vs. bearing two minute teeth); uropod 3 inner ramus with only 1 proximal seta (vs. armed with several marginal robust setae) and telson longer than broad (vs. broader than long).