Palaemon yuna, Carvalho, Fabricio Lopes, Magalhaes, Celio & Mantelatto, Fernando Luis, 2014

Carvalho, Fabricio Lopes, Magalhaes, Celio & Mantelatto, Fernando Luis, 2014, Molecular and morphological differentiation between two Miocene-divergent lineages of Amazonian shrimps, with the description of a new species (Decapoda, Palaemonidae, Palaemon), ZooKeys 457, pp. 79-108 : 88-92

Taxon classification Animalia Decapoda Palaemonidae

Palaemon yuna sp. n. Figures 3, 5c, 6c, 7and 8

Palaemonetes (Palaemonetes) carteri - Kensley and Walker 1982: 11, figs 13-14 [part, at least spec. from Rio Negro and its basin]; Melo 2003: 382 [part, Amazonas].

Palaemonetes carteri - Ramos-Porto and Coelho 1990: 99 [Rio Negro, Cantagalo; igarapé afluente do Rio Mapiri, Santarém?];– Pileggi et al. 2013: 569 [? part, material from rio Tapajós basin, rio Xingu and rio Trombetas].

Palaemonetes ivonicus - Ramos-Porto and Coelho 1990: 99 [part, Rio Negro, Cantagalo].

Holotype.

Lago Tupé beach, lower Rio Negro tributary, Manaus, Amazonas, Brazil (003°02'42"S, 060°15'10"W), ♂, col. FL Carvalho and EA Souza-Carvalho, 27 January 2012 (CCDB 4865).

Paratypes.

same data as holotype, 28♂ 8♀ 17♀ov (CCDB 4866); same data as holotype, 10♂ 3♀ 3♀ov (INPA 2016); same data as holotype, 1♂ 1♀ 1♀ov (OUMNH-ZC 2013-08-001).

Other material.

Brazil.Amazonas. Parque Nacional de Anavilhanas, lake near the rio Apuaí’s mouth, 1♂ 1♀, col. J Zuanon, 20 August 2005 (INPA 1432); Manaus, Rio Negro basin, Igarapé do Camarão, 20♀ov, col. O Odinetz-Collart et al., 28 February 1989 (CCDB 4726); Rio Negro basin, igarapé Alagadiço, 20♂, col. O Odinetz-Collart et al., 17 January 1989 (CCDB 4727); São Gabriel da Cachoeira, igarapé Barixia, right bank of the Rio Negro, 4♀, col. J Cunha et al., 14 December 2005 (MZUSP 16907); Santa Izabel do Rio Negro, 2♀, 24 October 1972 (MZUSP 13645); rio Uatumã, near the igarapé do Miriti’s mouth, 1♂ 3♀, col. C Magalhães, 12 July 1985 (INPA 173).

Diagnosis.

Mandibular palp absent. Rostrum slender, slightly curved upward at the distal half, overreaching the scaphocerite; dorsal margin with 6 to 10 teeth; ventral margin with 2 to 5 teeth, usually 3 or 4. Projection of the anterolateral margin of the first antennular segment reaching the dorsal distal margin of the second segment; anterolateral spine of the first antennular segment not overreaching the first third of the projection of the anterolateral margin. Appendix masculina up to 1.1 the length of the appendix interna, measured from their junction. Telson carrying 2 plumose setae between the inner distal stout setae; inner distal stout setae overreaching the distal tip of the telson.

Description.

Carapace glabrous. Sub-orbital lobe and pterygostomial angle rounded. Branchiostegal suture located approximately with a half of the distance between the antennal and branchiostegal tooth. Branchiostegal tooth almost as strong as the antennal, placed behind the anterior margin of the carapace.

Rostrum slender, slightly curved upward at the distal half, overreaching the scaphocerite (Fig. 7a); dorsal margin with 6 to 10 teeth, 5 to 8 of them placed in the proximal 2/3, 1 or 2 dorsal teeth located behind the orbit, 1 or 2 subapical teeth; ventral margin with 2 to 5 teeth, usually 3 or 4, all of them placed in the distal half. Single row of setae present on the proximal ventral portion up to the second tooth; double continuous and uniformly spaced row of setae on the distal half.

Eye well developed with pigmented cornea (Fig. 7b); cornea slightly wider and smaller than the eyestalk; ocellus present on dorsal side.

Antennular peduncle not reaching the distal margin of the scaphocerite; first antenular segment with outer margin slightly convex and projection of the anterolateral margin rounded, reaching the dorsal distal margin of the second segment (Fig. 5c); anterolateral spine of the first antennular segment not overreaching the first third of the projection of the anterolateral margin; second segment as broad as and shorter than the third segment; inner ventromesial tooth present; upper antennular flagellum fused for about 1/5 of its length (4-6 segments fused, 14-16 free); free portion with two rows of two or three aesthetascs on each segment. Stylocerite short, not reaching the middle of the first antennular segment. Béc ocellaire with anterior margin concave, pronounced upwardly and bearing a pigmented spot dorsally.

Scaphocerite slender (Fig. 7c), laminar, 3.3 times as long as broad; outer margin slightly concave, terminating in a tooth, not overreaching the lamella; basal segment of antenna with strong lateral tooth. Flagellum of the antenna more than five times the length of the body.

Mandibular palp absent; incisor process with three teeth on both sides (Fig. 7d). Upper lacina of the maxillula just reaching the length of the inner lacina (Fig. 7e). First maxilliped with lobes of the epipod fused (Fig. 7 h–i); anterior lobe elongated and almost triangular, with lateral border slightly convex; junction between the endites roundly curved. Epipod of the third maxilliped with anterior margin forming an angle of about 45° (Fig. 7j).

Thoracic sternal armature sexually similar. First thoracic sternite with an acute tooth and a conspicuous transverse ridge; second without tooth, bearing a triangular transverse ridge. Third to fifth without tooth and ridge incomplete.

First pereiopod slender (Fig. 7l), reaching the tip of scaphocerite with the fingers; ischium 1.8 times the length of basis; merus 1.7 times the length of ischium; carpus 1.3 times the length of merus; chela slightly less than 0.5 the length of carpus; fingers as long as palm (Fig. 7m).

Second pereiopod slender (Fig. 7k), overreaching the scaphocerite with about a half of the inflated distal part of the carpus; ischium about 4.5 times the length of basis; merus 0.8 the length of ischium; carpus 1.8 times the length of merus; chela about 0.6 times the length of carpus; fingers about 0.7 the length of palm (Fig. 7n).

Third pereiopod (Fig. 8a) slender, reaching the tip of the scaphocerite; ischium 1.8 times the length of basis; merus 1.9 times the length of ischium; carpus about 0.5 times the length of merus; propodus 1.6 times the length of carpus, ventral margin armed with 5-8 cuspidate setae; dactylus simple, about 0.3 times the length of the propodus.

Fourth pereiopod slender (Fig. 8b), overreaching the scaphocerite with all length of the dactylus; ischium 1.7 times the length of basis; merus 2.4 times the length of ischium; carpus about 0.5 length of merus; propodus 1.7 times the length of carpus, ventral margin armed with 7-13 cuspidate setae; dactylus simple, about 0.3 the length of propodus.

Fifth pereiopod slender (Fig. 8 c–d), overreaching the scaphocerite with the end of the propodus; ischium 1.7 times the length of basis; merus 2.3 times the length of ischium; carpus about 0.6 length of merus; propodus 2.1 times the length of carpus; grooming brush comprises about 10 rows of setae on the distal third of the propodus; dactylus simple, about 0.2 the length of propodus.

First pleopod without appendix interna and sexually dimorphic in proportions; males with endopod 0.5 the length of exopod (Fig. 8e); females with endopod approximately 0.3 length of exopod (Fig. 8f). Second to fifth pleopods similar, with the endopod reaching about 0.8 the length of exopod and bearing an appendix interna (Fig. 8g). Appendix masculina up to 1.1 times the length of the appendix interna, measured from their junction (Fig. 8h).

Abdominal sternal armature sexually dimorphic; males with first and second sternites bearing median process; second more acute and bigger than the first process; females with median process less develop than males.

Abdominal pleura furnished with plumose setae on ventral margin; fifth pleuron elongated and disto-ventrally rounded (Fig. 8i), with dorsal posterior border concave; sixth segment 1.63 times the length of the fifth; posterolateral margin with small tooth and keel disto-ventrally. Anal fig unarmed (Fig. 8j).

Telson as long as sixth pleonite; dorsal surface with two pairs of cuspidate setae (Fig. 8k); proximal dorsal tuft of setae reduced to one or two simple setae; marginal setae absent; posterior margin ending abruptly in a triangular tip, not overreaching the inner stout setae (Fig. 8l); 1 pair of plumose setae and 2 pairs of stout setae, inner pair of stout setae about 2.3 times the length of the outer pair.

Uropods overreaching the telson by 0.3 of the length of exopod; exopod 1.25 times the length of endopod; mobile distolateral setae of exopod weak, reaching about the middle of the fixed tooth (Fig. 8m).

Geographic distribution.

Brazil (Amazonas, Pará?), Venezuela? (Apure).

Ecological features.

Usually associated with riparian vegetation, leaf litter and similar microhabitats in lakes, streams and rivers of black or clear water river systems, in areas with low flow.

Etymology.

The specific epithet is derived from the Tupi, the general language of the Brazilian indigenous people: y = water, river + úna = black, alluding to the environment where the species was first found (Fig. 9).